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Sample records for batu hijau porphyry

  1. Trace metals associated with deep-sea tailings placement at the Batu Hijau copper-gold mine, Sumbawa, Indonesia.

    PubMed

    Angel, Brad M; Simpson, Stuart L; Jarolimek, Chad V; Jung, Rob; Waworuntu, Jorina; Batterham, Grant

    2013-08-15

    The Batu Hijau copper-gold mine on the island of Sumbawa, Indonesia operates a deep-sea tailings placement (DSTP) facility to dispose of the tailings within the offshore Senunu Canyon. The concentrations of trace metals in tailings, waters, and sediments from locations in the vicinity of the DSTP were determined during surveys in 2004 and 2009. In coastal and deep seawater samples from Alas Strait and the South Coast of Sumbawa, the dissolved concentrations of Ag, As, Cd, Cr, Hg, Pb and Zn were in the sub μg/L range. Dissolved copper concentrations ranged from 0.05 to 0.65 μg/L for all depths at these sites. Dissolved copper concentrations were the highest in the bottom-water from within the tailings plume inside Senunu Canyon, with up to 6.5 μg Cu/L measured in close proximity to the tailings discharge. In general, the concentrations of dissolved and particulate metals were similar in 2004 and 2009.

  2. Porphyry of Russian Empires in Paris

    NASA Astrophysics Data System (ADS)

    Bulakh, Andrey

    2014-05-01

    Porphyry of Russian Empires in Paris A. G. Bulakh (St Petersburg State University, Russia) So called "Schokhan porphyry" from Lake Onega, Russia, belongs surely to stones of World cultural heritage. One can see this "porphyry" at facades of a lovely palace of Pavel I and in pedestal of the monument after Nicolas I in St Petersburg. There are many other cases of using this stone in Russia. In Paris, sarcophagus of Napoleon I Bonaparte is constructed of blocks of this stone. Really, it is Proterozoic quartzite. Geology situation, petrography and mineralogical characteristic will be reported too. Comparison with antique porphyre from the Egyptian Province of the Roma Empire is given. References: 1) A.G.Bulakh, N.B.Abakumova, J.V.Romanovsky. St Petersburg: a History in Stone. 2010. Print House of St Petersburg State University. 173 p.

  3. Preliminary Model of Porphyry Copper Deposits

    USGS Publications Warehouse

    Berger, Byron R.; Ayuso, Robert A.; Wynn, Jeffrey C.; Seal, Robert R., II

    2008-01-01

    The U.S. Geological Survey (USGS) Mineral Resources Program develops mineral-deposit models for application in USGS mineral-resource assessments and other mineral resource-related activities within the USGS as well as for nongovernmental applications. Periodic updates of models are published in order to incorporate new concepts and findings on the occurrence, nature, and origin of specific mineral deposit types. This update is a preliminary model of porphyry copper deposits that begins an update process of porphyry copper models published in USGS Bulletin 1693 in 1986. This update includes a greater variety of deposit attributes than were included in the 1986 model as well as more information about each attribute. It also includes an expanded discussion of geophysical and remote sensing attributes and tools useful in resource evaluations, a summary of current theoretical concepts of porphyry copper deposit genesis, and a summary of the environmental attributes of unmined and mined deposits.

  4. Exotism of Batu Putih area in Samarinda, East Kalimantan as conservation area for ecotourism destination

    NASA Astrophysics Data System (ADS)

    Sutan, Syamsidar; Cahyani, Rina Wahyu; Alam, Fajar; Syuhada, Endy Mukhlis

    2017-02-01

    Batu Putih is a limestone hill complex in Air Putih area, Samarinda, East Kalimantan. The unique value of this region is a towering limestone ridge which easily recognizable at a distance, water catchment area in the city, great place to learn earth science as understanding the ancient marine deposition and hydrocarbon potential development, and the heritage of the region. The objective of this research is toreview the potential of Batu Putih area and surrounding as a green conservation area for ecotourism destination. Batu Putih area, geologically part of Kutai Basin, is controlled by tectonic event, resulted on Northeast-Southwest undulated trend known as Samarinda anticlinorium. Data collected cover several aspects: (1) geological aspects: various types of rocks, groundwater condition and other related data; (2) vegetation aspects; (3) cultural aspect: heritage and historical place. By results from evaluation of existing data, development plan will be commenced. Research found 2 spots for landscape viewing, 3 water resources, various marine fossils in some locations and mud volcano. Vegetations are dominated by "kersen" (Muntingia calabura L.), "aren" (Arenga pinnata) and "pletekan" (Ruellia tuberosa). Based on the findings of the existing kinds of uniqueness, conservation of the area are mandatories. Protection and preservation of the region in integrated manner and area development for ecotourism and education are things should be done in Batu Putih, as increasingly damaged and depleted by limestone mining activities using heavy equipment.

  5. Dynamics of strombolian eruptions at Batu Tara volcano (Indonesia)

    NASA Astrophysics Data System (ADS)

    Scarlato, P.; Del Bello, E.; Gaudin, D.; Taddeucci, J.; Ricci, T.; Cesaroni, C.

    2015-12-01

    In September 2014, high-speed imaging and acoustic data were acquired during 3 days of almost continuous recording (04-06/09/2015) at Batu Tara Volcano, in the small isolated island of Pulau Komba, in the Flores Sea (about 50 km N of Lembata). This volcano is very similar to the Italian Stromboli Volcano in both eruptive style and edifice morphology. The field experiment aimed at investigating degassing and explosive dynamics using a combination of GPS synchronized devices deployed in direct view of the active vent: i) a high-speed visible camera acquiring images at 500 frames per second (fps),ii) a thermal infrared (FLIR) camera acquiring at 50-200 fps, iii) a visible time lapse camera (GO-PRO) acquiring at 0.2-0.5 Hz (2 - 5 s interval), iv) two broadband microphones (Freq. range of kHz to 0.1 Hz) sampled at 10 kHz. Explosions can be discriminated in type according to their visual, thermal and acoustic features.Some explosions are characterized by a first sudden radial ejection of large spatter and bombs (main pulse), eventually followed by other similar events (secondary pulses), with very little amount of ash involved. In these eruptions, infrasonic waveforms are characterized by a first, high amplitude transient, with a first positive peak pressure followed by rapid dampening, typical of a Strombolian eruption.Other explosions are characterized by the sustained ejection of a dense jet of ash, with abundant decimeter to meter sized spatter and hot blocks.These eruptions are not accompanied by a maximum peak pressure at the eruption onset. Spectrograms show a high frequency component propagating for the entire duration of the signal.These two distinct types are sometimes overlapping and eruptions show a high amplitude transient followed by a high frequency coda. These different evolutions suggest that there are at least two repeatable explosion dynamics occurring in the conduit, with comparable gas overpressure, source depth and amount of gas involved

  6. Environmental behavior of two molybdenum porphyry systems

    USGS Publications Warehouse

    Tuttle, M.L.W.; Wanty, R.B.; Berger, B.R.

    2004-01-01

    Our study focuses on the geology, hydrology, and geochemistry of a variety of molybdenum (Mo) porphyry systems. The systems are either high fluorine, granite, Climax-type, systems (e.g. Mount Emmons/ Redwell Mo deposit, Colorado and Questa Mo deposit, New Mexico) or low fluorine granodiorite systems (e.g. Buckingham Stockwork Mo deposit, Battle Mountain, Nevada and Cannivan Gulch Mo deposit, Montana). The water quality of streams, natural springs, mine discharge, and ground water from drill holes were assessed in the region of these deposits. The ultimate goal of our study is to understand the environmental behavior of these Mo porphyry systems in the context of geologic setting, hydrologic regime, and climate.

  7. Porphyry copper enrichment linked to excess aluminium in plagioclase

    NASA Astrophysics Data System (ADS)

    Williamson, B. J.; Herrington, R. J.; Morris, A.

    2016-03-01

    Porphyry copper deposits provide around 75%, 50% and 20% of world copper, molybdenum and gold, respectively. The deposits are mainly centred on calc-alkaline porphyry magmatic systems in subduction zone settings. Although calc-alkaline magmas are relatively common, large porphyry copper deposits are extremely rare and increasingly difficult to discover. Here, we compile existing geochemical data for magmatic plagioclase, a dominant mineral in calc-alkaline rocks, from fertile (porphyry-associated) and barren magmatic systems worldwide, barren examples having no associated porphyry deposit. We show that plagioclase from fertile systems is distinct in containing `excess’ aluminium. This signature is clearly demonstrated in a case study carried out on plagioclase from the fertile La Paloma and Los Sulfatos copper porphyry systems in Chile. Further, the presence of concentric zones of high excess aluminium suggests its incorporation as a result of magmatic processes. As excess aluminium has been linked to high melt water contents, the concentric zones may record injections of hydrous fluid or fluid-rich melts into the sub-porphyry magma chamber. We propose that excess aluminium may exclude copper from plagioclase, so enriching the remaining melts. Furthermore, this chemical signature can be used as an exploration indicator for copper porphyry deposits.

  8. Porphyry deposits of the Canadian Cordillera

    USGS Publications Warehouse

    McMillan, W.J.; Thompson, J.F.H.; Hart, C.J.R.; Johnston, S.T.

    1996-01-01

    Porphyry deposits are intrusion-related, large tonnage low grade mineral deposits with metal assemblages that may include all or some of copper, molybdenum, gold and silver. The genesis of these deposits is related to the emplacement of intermediate to felsic, hypabyssal, generally porphyritic intrusions that are commonly formed at convergent plate margins. Porphyry deposits of the Canadian Cordillera occur in association with two distinctive intrusive suites: calc-alkalic and alkalic. In the Canadian Cordillera, these deposits formed during two separate time periods: Late Triassic to Middle Jurassic (early Mesozoic), and Late Cretaceous to Eocene (Mesozoic-Cenozoic). Deposits of the early Mesozoic period occur in at least three different arc terranes (Wrangellia, Stikinia and Quesnellia) with a single deposit occurring in the oceanic assemblage of the Cache Creek terrane. These terranes were located outboard from continental North America during formation of most of their contained early Mesozoic porphyry deposits. Some of the deposits of this early period may have been emplaced during terrane collisions. Metal assemblages in deposits of the calc-alkalic suite include Mo-Cu (Brenda), Cu-Mo (Highland Valley, Gibraltar), Cu-Mo-Au-Ag (Island Copper, Schaft Creek) and Cu-Au (Kemess, Kerr).The alkalic suite deposits are characterized by a Cu-Au assemblage (Copper Mountain, Afton-Ajax, Mt. Milligan, Mount Polley, Galore Creek). Although silver is recovered from calc-alkalic and alkalic porphyry copper mining operations, silver data are seldom included in the published reserve figures. Those available are in the range of 1-2 grams per tonne (g??t-1). Alkalic suite deposits are restricted to the early Mesozoic and display distinctive petrology, alteration and mineralization that suggest a similar tectonic setting for both Quesnellia and Stikinia in Early Jurassic time. The younger deposits, late Mesozoic to Cenozoic in age, formed in an intracontinental setting, after the

  9. Late Cretaceous porphyry copper mineralization in Sonora, Mexico: Implications for the evolution of the Southwest North America porphyry copper province

    NASA Astrophysics Data System (ADS)

    Barra, Fernando; Valencia, Victor A.

    2014-10-01

    Two porphyry Cu-Mo prospects in northern Sonora, Mexico (Fortuna del Cobre and Los Humos) located within the southwestern North American porphyry province have been dated in order to constrain the timing of crystallization and mineralization of these ore deposits. In Fortuna del Cobre, the pre-mineralization granodiorite porphyry yielded an U-Pb zircon age of 76.5 ± 2.3 Ma, whereas two samples from the ore-bearing quartz feldespathic porphyry were dated at 74.6 ± 1.3 and 75.0 ± 1.4 Ma. Four molybdenite samples from Los Humos porphyry Cu prospect yielded a weighted average Re-Os age of 73.5 ± 0.2 Ma, whereas two samples from the ore-bearing quartz monzonite porphyry gave U-Pb zircon ages of 74.4 ± 1.1 and 74.5 ± 1.3 Ma, showing a Late Cretaceous age for the emplacement of this ore deposit. The results indicate that Laramide porphyry Cu mineralization of Late Cretaceous age is not restricted to northern Arizona as previously thought and provide evidence for the definition of NS trending metallogenic belts that are parallel to the paleo-trench. Porphyry copper mineralization follows the inland migration trend of the magmatic arc as a result of the Farallon slab flattening during the Laramide orogeny.

  10. Climax-Type Porphyry Molybdenum Deposits

    USGS Publications Warehouse

    Ludington, Steve; Plumlee, Geoffrey S.

    2009-01-01

    Climax-type porphyry molybdenum deposits, as defined here, are extremely rare; thirteen deposits are known, all in western North America and ranging in age from Late Cretaceous to mainly Tertiary. They are consistently found in a postsubduction, extensional tectonic setting and are invariably associated with A-type granites that formed after peak activity of a magmatic cycle. The deposits consist of ore shells of quartz-molybdenite stockwork veins that lie above and surrounding the apices of cupola-like, highly evolved, calc-alkaline granite and subvolcanic rhyolite-porphyry bodies. These plutons are invariably enriched in fluorine (commonly >1 percent), rubidium (commonly >500 parts per million), and niobium-tantalum (Nb commonly >50 parts per million). The deposits are relatively high grade (typically 0.1-0.3 percent Mo) and may be very large (typically 100-1,000 million tons). Molybdenum, as MoS2, is the primary commodity in all known deposits. The effect on surface-water quality owing to natural influx of water or sediment from a Climax-type mineralized area can extend many kilometers downstream from the mineralized area. Waste piles composed of quartz-silica-pyrite altered rocks will likely produce acidic drainage waters. The potential exists for concentrations of fluorine or rare metals in surface water and groundwater to exceed recommended limits for human consumption near both mined and unmined Climax-type deposits.

  11. Application of Geographic Information Systems (GIS) in Analysing Rainfall Distribution Patterns in Batu Pahat District

    NASA Astrophysics Data System (ADS)

    Kadir, A. A.; Kaamin, M.; Azizan, N. S.; Sahat, S.; Bukari, S. M.; Mokhtar, M.; Ngadiman, N.; Hamid, N. B.

    2016-07-01

    Rainfall forecasting reports are crucial to provide information and warnings to the population in a particular location. The Malaysian Meteorology Department (MMD) is a department that plays an important role in monitoring the situation and issued the statement of changes in weather and provides services such as weather advisories and gives warnings when the situation requires. Uncertain weather situations normally have created panic situation, especially in big cities because of flash floods due to poor drainage management. Usually, local authorities provided rainfall data in tables, and it is difficult to analyse to acquire the rainfall trend. Therefore, Geographic Information System (GIS) applications are commonly used to generate rainfall patterns in visual formation with a combination of characteristics of rainfall data and then can be used by stakeholders to facilitate the process of analysis and forecasting rainfall. The objective of this study is to determine the pattern of rainfall distribution using GIS applications in Batu Pahat district to assist interested parties to understand and easy to analyse the rainfall data in visual form or mapping form. Rainfall data for a period of 10 years (2004-2013) and monthly data (Dec 2006 - Feb 2007) are provided by the Department of Irrigation and Drainage (DID) for 12 stations in the district of Batu Pahat, and rainfall maps in each year was obtained using the interpolation Inverse Distance Weighted (IDW) method was used in this research. The rainfall map was then analyzed to identify the highest rainfall that was received during the period of study. For the conclusion, this study has proved that rainfall analysis using GIS application is efficient to be used in gaining information of rainfall patterns as the results show that the highest rainfall occurred in 2006 and 2007, and it were the years of major floods occurrence in Batu Pahat district.

  12. The Dala (Älvdalen) Porphyries from Sweden

    NASA Astrophysics Data System (ADS)

    Wikström, Anders; Pereira, Lola; Lundqvist, Thomas; Cooper, Barry

    2014-05-01

    The Dala (Älvdalen) Porphyries from Sweden Anders Wikström (retired from Geological Survey of Sweden) Lola Pereira (University of Salamanca, Spain) Thomas Lundqvist (retired from Geological Survey of Sweden) Barry Cooper (University of South Australia) The commercial stone industry in Älvdalen, about 350 km northwest of Stockholm, commenced in the second half of the 18th century, as a consequence of social need. The region had been plagued by severe famine and there was an urgent need for additional wealth-generating industry. At that time it was already known that the porphyry in the area was similar to the "porfido rosso antico" from Egypt which had played an important role in the Roman culture. Many ups and downs followed. During one period in the 19th century, the Swedish Royal family owned the industry. At the same time, several "porphyry" objects were presented to different courts around Europe (e.g. a 4 metre tall vase to the Russian czar, although of a more granitic variety). Otherwise most products have been smaller objects like urns, vases, candelabras, etc. The very hard stone (with variable red or black colours) can be highly polished. Many of the porphyry varieties were sourced from glacial boulders. These had been "mechanically tested" by nature and were free from joints which otherwise was a problem in the associated quarries. Comagmatic granites also occur. The porphyries and granites have an age around 1700 Ma, and the former are amazingly well preserved with magnificent volcanic textures. The porphyries and granites occupy a vast area and are in part covered with red, continental sandstones (which are quarried to-day). In the middle of the 20th century, the ignimbritic character of the porphyry was discovered. Previously, the flattened "fiamme" (collapsed pumice) had been interpreted as some kind of flow structure in a lava. The porphyry manufacturing plants in Älvdalen are a part of the Swedish industrial history. Over a significant

  13. Recognition of the geologic framework of porphyry deposits on ERTS-1 imagery. [copper/molybdenum porphyrys

    NASA Technical Reports Server (NTRS)

    Wilson, J. C. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. Three major tectonic provinces have been mapped by geologic photointerpretation of ERTS-1 imagery over the Ok Tedi test site. These areas can be characterized as follows: (1) A broad area of low relief and mature topography suggesting a history of relative tectonic stability. (2) A narrow belt of moderate to high relief, broad open folds and prominent linear features. The Mount Fubilan-type porphyry copper deposits and recent volcanic effusive centers occur in this province. (3) A heterogeneous zone of high relief and high drainage density suggestive of relative structural complexity.

  14. The geology and geochemistry of Philippine Porphyry copper deposits

    NASA Astrophysics Data System (ADS)

    Divis, Allan F.

    Porphyry copper deposits and their relationship to felsic intrusions are of considerable economic as well as academic interest. They generally occur near continental margins and in island arcs. Although some conjecture exists as to the ultimate source of transition metals associated with the deposits, a growing body of evidence suggests the metals are principally derived from a magmatic source: the porphyry intrusions. These intrusions may also give rise to adjacent vein and precious metal deposits. Over 40 potential deposits have been reported in the Philippine island arc and approximately nine are or have been in production. The known and inferred reserves from these deposits exceed three billion metric tons of ore— approximately 10 to 20 million tons of metallic copper. Several deposits may ultimately have more than a billion tons of ore reserves. There appears to be a remarkable correlation between the timing of porphyry intrusions in the Philippines and that in other areas, particularly New Guinea and the Solomon Islands. These intrusions also show a close relationship to the timing of oceanic plate tectonic processes. Periods of increased subduction rate and accompanying dilation and/or shearing within the arc may be conducive to the generation of porphyry magmas on an episodic rather than continuous basis. Ultimately, the development of an economically significant ore body requires the presence of a hydrous magma and may be associated with other primary compositional characteristics. However, anomalous high primary magmatic concentrations of copper do not appear to be required for the formation of the porphyry deposits. The Philippine porphyry intrusions differ somewhat from `continental' porphyries and are chemically similar to mineralized island arc intrusions of the Carribean and the southwest Pacific. The Philippine intrusions generally range from diorites and quartz diorites to low potassium granodiorites. Initial 87-Sr/86-Sr ratios are low, ranging

  15. Island history affects faunal composition: the treeshrews (Mammalia: Scandentia: Tupaiidae) from the Mentawai and Batu Islands, Indonesia

    USGS Publications Warehouse

    Sargis, Eric J.; Woodman, Neal; Morningstar, Natalie C.; Reese, Aspen T.; Olson, Link E.

    2014-01-01

    The Mentawai and Batu Island groups off the west coast of Sumatra have a complicated geological and biogeographical history. The Batu Islands have shared a connection with the Sumatran ‘mainland’ during periods of lowered sea level, whereas the Mentawai Islands, despite being a similar distance from Sumatra, have remained isolated from Sumatra, and probably from the Batu Islands as well. These contrasting historical relationships to Sumatra have influenced the compositions of the respective mammalian faunas of these island groups. Treeshrews (Scandentia, Tupaiidae) from these islands have, at various times in their history, been recognized as geographically circumscribed populations of a broadly distributed Tupaia glis, subspecies, or distinct species. We used multivariate analyses of measurements from the skull and hands to compare the island populations from Siberut (Mentawai Islands) and Tanahbala (Batu Islands) with the geographically adjacent species from the southern Mentawai Islands (T. chrysogaster) and Sumatra (T. ferruginea). Results from both the skull and manus of the Siberut population show that it is most similar to T. chrysogaster, whereas the Tanahbala population is more similar to T. ferruginea, confirming predictions based on island history. These results are further corroborated by mammae counts. Based on these lines of evidence, we include the Siberut population in T. chrysogaster and the Tanahbala population in T. ferruginea. Our conclusions expand the known distributions of both the Mentawai and Sumatran species. The larger geographical range of the endangered T. chrysogaster has conservation implications for this Mentawai endemic, so populations and habitat should be re-evaluated on each of the islands it inhabits. However, until such a re-evaluation is conducted, we recommend that the IUCN Red List status of this species be changed from ‘Endangered’ to ‘Data Deficient’.

  16. A Study of Geological Formation on Different Sites in Batu Pahat, Malaysia Based On HVSR Method Using Microtremor Measurement

    NASA Astrophysics Data System (ADS)

    Noor, M. A. M.; Madun, A.; Kamarudin, A. F.; Daud, M. E.

    2016-07-01

    Geological formation is a one of information need to know during site reconnaissance. Conventional method like borehole has been known is very accurate to identify the formation of geology of a site. However, the problem of this technique is very expensive and not economical for large area. In the last decade, microtremor measurement has been introduced as an alternative technique and widely used in the geological formation study. Therefore, the aim in this study is to determine the geological formation underneath of surface in Batu Pahat district using microtremor measurement. There are two parameters have been carried out from microtremor measurement in term of natural frequency and HVSR curves images. Microtremor measurements are done conducted at 15 sites surrounding of Batu Pahat. Horizontal to vertical spectral ratio (HVSR) method was used for analyzing microtermor measurement data, to determine the natural frequency and also HVSR curves image. In this study, values of natural frequencies are used to classify the soil types with range in the between 0.93 to 5.35 Hz, meanwhile the pattern of HVSR curve images has been shown exists a few groups of soil types surrounding Batu Pahat district. Hence, microtremor measurement indirectly can be used as a one technique to add value in the site reconnaissance in the future.

  17. Isolation and characterization of Heat Shock Protein 100-Batu1 from Toxoplasma gondii RH strain.

    PubMed

    Coşkun, Kübra Açıkalın; Tutar, Yusuf

    2015-06-01

    Toxoplasma gondii is an intracellular parasitic protozoon which infects human and most warm-blooded animals. Almost one-third of the world's population is affected by life-threatening infection of T. gondii tachyzoites form. Slow growing, transmissible and encysted bradyzoites forms are composed after tachyzoites stage. Cellular and environmental stresses induce conversion of tachyzoites from bradyzoites and this condition is associated with Heat Shock Protein (Hsps) family. Hsp100 is a member of this protein family, and coordinates to disassemble protein aggregates with Hsp70 and Hsp40 in an ATP dependent manner. Several proteins are involved during this stage differentiation and Hsp100 may help them to be in their native soluble form to perform their function as observed in other organisms. For this purpose, Hsp100-Batu1 was isolated from T. gondii RH strain to characterize its biochemical properties in this current study. Hsp100 proteins play a role in survival and virulence of pathogens as shown in the literature. Therefore, manipulation of protein-protein interaction may perturb T. gondii infection and impair conversion to tachyzoites by inhibiting Hsp100 function. Therefore, results of this work present a potential route for vaccination or immunotherapy.

  18. Cyrts in the city: a new Bent-toed Gecko (Genus Cyrtodactylus) is the only endemic species of vertebrate from Batu Caves, Selangor, Peninsular Malaysia.

    PubMed

    Grismer, L Lee; Wood, Perry L; Onn, Chan Kin; Anuar, Shahrul; Muin, Mohd Abdul

    2014-03-07

    Cyrtodactylus metropolis sp. nov. from Batu Caves massif, Selangor, Peninsular Malaysia is differentiated from all congeners by having a unique suite of morphological and color pattern characteristics. Remarkably, this species has been overlooked despite a plethora of field studies at Batu Caves from 1898 to the present and no specimens had ever been examined until now. As with all other limestone forest-adapted Cyrtodactylus in Peninsular Malaysia, C. metropolis sp. nov. is not a cave-adapted species but is far more common on the exterior surfaces of the Batu Caves limestone massif and its surrounding limestone vegetation. We suggest that researchers devote time exploring the exterior surfaces of limestone massifs as well the interiors of their caves.

  19. The Myszkow porphyry copper-molybdenum deposit, Poland

    USGS Publications Warehouse

    Chaffee, M.A.; Eppinger, R.G.; Lason, K.; Slosarz, J.; Podemski, M.

    1994-01-01

    The porphyry copper-molybdenum deposit at Myszkow, south-central Poland, lies in the Cracow-Silesian orogenic belt, in the vicinity of a Paleozoic boundary between two tectonic plates. The deposit is hosted in a complex that includes early Paleozoic metasedimentary rocks intruded in the late Paleozoic by a predominantly granodioritic pluton. This deposit exhibits many features that are typical of porphyry copper deposits associated with calc-alkaline intrusive rocks, including ore- and alteration-mineral suites, zoning of ore and alteration minerals, fluid-inclusion chemistry, tectonic setting, and structural style of veining. Unusual features of the Myszkow deposit include high concentrations of tungsten and the late Paleozoic (Variscan) age. -Authors

  20. Timescales of Porphyry Cu Formation: Bajo de la Alumbrera, NW Argentina

    NASA Astrophysics Data System (ADS)

    Buret, Y.; Von Quadt, A.; Heinrich, C. A.; Peytcheva, I.

    2014-12-01

    Using high-precision U-Pb dating we are potentially able to determine timescales of porphyry emplacement and ore formation. Previous studies have suggested timescales of porphyry Cu formation ranging from <100 yr, based on modelling diffusive equilibrium between fluids and altered rocks [1], to as much as 1 Ma using U-Pb LA-ICP-MS and SHRIMP dating techniques on zircons [2], [3]. In contrast recent numerical simulations suggest Cu precipitation occurs in the range of 50-100 ka [4]. Therefore in order to better constrain timescales of porphyry Cu formation, we apply high precision U-Pb zircon geochronology, using the youngest zircon date to estimate the emplacement age of each porphyry [5].This study focuses on the ~7 Ma Bajo de la Alumbrera Cu-Au deposit, NW Argentina. The deposit consists of a composite stock of dacitic porphyries. The relative timing of each porphyry intrusion is established based on clear cross-cutting relationships between different porphyry intrusions, which include the pre-mineralisation P2 porphyry, pre-syn-minerlisation EP3 porphyry, and the post-mineralisation LP3 and P4 porphyries.Single zircon crystals from individual porphyry intrusions (P2, EP3, LP3, P4) in the Alumbrera deposit have been dated using CA-ID-TIMS, employing the ET2535 tracer solution for maximum precision and accuracy. All porphyries display protracted zircon crystal growth over 100-200 ka timescales. Using the youngest zircons from each of the porphyry intrusions, Cu mineralisation occurred on 10 ka timescales, similar to those proposed by recent numerical predictions [4]. Trace element and Hf isotopic analyses may reveal geochemical distinctions within the porphyry intrusions and record temporal changes in the magmatic evolution. References: [1] Cathles and Shannon (2007) EPSL 262:92-108; [2] Ballard et al. (2001) Geology 29:383-386; [3] Harris et al. (2008) Min Dep 43: 295-314; [4] Weis et al. (2012) Science 338: 1613-1616; [5] von Quadt et al. (2011) Geology 39: 731-734.

  1. Porphyry molybdenum deposits in the Tianshan-Xingmeng orogenic belt, northern China

    NASA Astrophysics Data System (ADS)

    Zeng, Qingdong; Qin, Kezhang; Liu, Jianming; Li, Guangming; Zhai, Mingguo; Chu, Shaoxiong; Guo, Yunpeng

    2015-06-01

    Molybdenum (Mo) exploration activity in China has increased tremendously over the past decade, and China is now known to have the largest Mo reserves in the world. The Tianshan-Xingmeng orogenic belt, the second largest Mo metallogenic belt, possesses over 8.2 Mt of Mo reserves. Porphyry Mo deposits contain 99 % of the Mo reserves in the Tianshan-Xingmeng orogenic belt; other Mo deposits contain 1 % of the Mo reserves. Five subtypes of the porphyry Mo deposits can be distinguished by deposit associations, such as Mo, Mo-Cu, Mo-W, Mo-Pb-Zn-Ag, and Cu-Mo deposits. These porphyry Mo deposits are formed at different stages: during the Ordovician, Devonian, Carboniferous, Late Permian, Triassic, Jurassic, and Cretaceous Periods. The polystage porphyry Mo mineralizations indicate that polystage tectonic-magmatic activity occurred in the orogenic belt. The Ordovician-Carboniferous porphyry Cu-Mo deposits are formed in an island-arc setting; the Late Permian porphyry Mo deposits are formed in a syn-collisional tectonic setting; and the Triassic porphyry Mo deposits are formed in a syn-collisional to post-collisional tectonic setting. The Ordovician-Triassic porphyry deposits are related to the Paleo-Asian Ocean tectonic system. The Jurassic porphyry Mo deposits are formed at the eastern margin of the Asian continent and are associated with a Paleo-Pacific plate-subduction tectonic setting. Cretaceous porphyry Mo deposits are formed in a lithospheric thinning setting and are related to the rollback of the Paleo-Pacific subduction plate.

  2. Organic petrological and organic geochemical characterisation of the Tertiary coal-bearing sequence of Batu Arang, Selangor, Malaysia

    NASA Astrophysics Data System (ADS)

    Wan Hasiah, Abdullah; Abolins, Peter

    1998-08-01

    The Tertiary coal-bearing sequence at Batu Arang in Selangor, Peninsular Malaysia consists of a sandstone-coal-oil shale facies assemblage. A detailed organic petrological and organic geochemical study was carried out on several organic-rich sediments from this sequence. The oil shales are dominated by Botryococcus-derived telalginite and Pediastrum-derived lamalginite. The coals, hypautochthonous in origin, are mainly duroclarite-type, although other minor microlithotypes also occur. Alginite is not observed in the coals, but other liptinitic constituents are very common, particularly thin-walled cutinite and sporinite. The oil shales and the coals are thermally immature. This immaturity has a considerable influence on the biomarker distributions, particularly so on the triterpanes which are dominated by C 31αβ 22R and C 30ββ compounds. Interestingly, for Tertiary aged sediments of continental origin, the diagnostic biomarker compounds such as 18 α(H)-oleanane and bicadinanes, normally linked to the higher land plant group of angiosperms, are not observed in the samples analysed. Tricyclic terpanes occur only in very low relative abundance or are virtually absent. A clear distinction, however, in the biomarker distributions of the shales and the coals/carbargilite can be made based upon the distribution of C 27-C 29 regular steranes: the shales, with a source input being predominantly planktonic algae, are dominated by 5 α(H),14 α(H),17 α(H) 20R cholestane, while the coals/carbargilites, with a source input consisting mainly of higher plant material, are dominated by 5 α(H),14 α(H),17 α(H) 20R ethyl cholestane. The depositional environment of the Batu Arang coal-bearing sequence is interpreted as varying from an alluvial flood plain peat-swamp to fluvio-lacustrine depositional setting.

  3. Mo isotope fractionation during hydrothermal evolution of porphyry Cu systems

    NASA Astrophysics Data System (ADS)

    Shafiei, Behnam; Shamanian, GholamHossein; Mathur, Ryan; Mirnejad, Hassan

    2015-03-01

    We present Mo isotope compositions of molybdenite types from three successive stages of ore deposition in several porphyry copper deposits of the Kerman region, Iran. The data provide new insights into controlling processes on Mo isotope fractionation during the hydrothermal evolution of porphyry systems. The Mo isotope compositions of 27 molybdenite samples show wide variations in δ97Mo ranging from -0.37 to +0.92 ‰. The data reveal that molybdenites in the early and transitional stages of mineralization (preferentially 2H polytypes; δ97Mo mean = 0.35 ‰) have higher δ97Mo values than late stage (mainly 3R polytypes; δ97Mo mean = 0.02 ‰) molybdenites. This trend suggests that fractionation of Mo isotopes occurred in high-temperature stages of mineralization and that hydrothermal systems generally evolve towards precipitation of molybdenite with lower δ97Mo values. Taking into account the genetic models proposed for porphyry Cu deposits along with the temperature-dependent fractionation of Mo isotope ratios, it is proposed that large variations of Mo isotopes in the early and the transitional stages of ore deposition could be controlled by the separation of the immiscible ore-forming fluid phases with different density, pH, and ƒO2 properties (i.e., brine and vapor). The fractionation of Mo isotopes during fluid boiling and Rayleigh distillation processes likely dominates the Mo isotope budget of the remaining ore-forming fluids for the late stage of mineralization. The lower δ97Mo values in the late stage of mineralization can be explained by depletion of the late ore-forming hydrothermal solutions in 97Mo, as these fluids have moved to considerable distance from the source. Finally, the relationship observed between MoS2 polytypes (2H and 3R) and their Mo isotopic compositions can be explained by the molecular vibration theory, in which heavier isotopes are preferentially partitioned into denser primary 2H MoS2 crystals.

  4. El Salvador, Chile porphyry copper deposit revisited: Geologic and geochronologic framework

    USGS Publications Warehouse

    Cornejo, P.; Tosdal, R.M.; Mpodozis, C.; Tomlinson, A.J.; Rivera, O.; Fanning, C.M.

    1997-01-01

    The Eocene (42 to 41 Ma) El Salvador porphyry copper deposit in the Indio Muerto district, northern Chile (26?? 15??? S Lat.), formerly thought to have formed at the culmination of a 9-m.y. period of episodic magmatism, is shown by new mapping, U-Pb and K-Ar geochronology, and petrologic data to have formed during the younger of two distinct but superposed magmatic events - a Paleocene (???63 to 58 Ma) and an Eocene (44 to 41 Ma) event. In the district, high-K Paleocene volcano-plutonic activity was characterized by a variety of eruptive styles and magmatic compositions, including a collapse caldera associated with explosive rhyolitic magmatism (El Salvador trap-door caldera), a post-collapse rhyolite dome field (Cerro Indio Muerto), and andesitic-trachyandesitic stratovolcanos (Kilo??metro Catorce-Los Amarillos sequence). Precaldera basement faults were reactivated during Paleocene volcanism as part of the collapse margin of the caldera. Beneath Cerro Indio Muerto, where the porphyry Cu deposit subsequently formed, the intersection of two major basement faults and the NNE-striking rotational axis of tilted ignimbrites of the Paleocene El Salvador caldera localized emplacement of post-collapse rhyolite domes and peripheral dikes and sills. Subsequent Eocene rhyolitic and granodioritic-dacitic porphyries intruded ???14 m.y. after cessation of Paleocene magmatism along the same NNE-striking structural belt through Cerro Indio Muerto as did the post-collapse Paleocene rhyolite domes. Eocene plutonism over a 3-m.y. period was contemporaneous with NW-SE-directed shortening associated with regional sinistral transpression along the Sierra Castillo fault, lying ???10 km to the east. Older Eocene rhyolitic porphyries in the Indio Muerto district were emplaced between 44 and 43 Ma, and have a small uneconomic Cu center associated with a porphyry at Old Camp. The oldest granodioritic-dacitic porphyries also were emplaced at ???44 to 43 Ma, but their petrogenetic relation to

  5. 3D electrical structure of porphyry copper deposit: A case study of Shaxi copper deposit

    NASA Astrophysics Data System (ADS)

    Chen, Xiang-Bin; Lü, Qing-Tian; Yan, Jia-Yong

    2012-06-01

    Located in Lu-Zong ore concentration area, middle-lower Yangtze metallogenic belt, ShaXi porphyry copper deposit is a typical hydrothermal deposit. To investigate the distribution of deep ore bodies and spatial characteristics of host structures, an AMT survey was conducted in mining area. Eighteen pseudo-2D resistivity sections were constructed through careful processing and inversion. These sections clearly show resistivity difference between the Silurian sandstones formation and quartz diorite porphyry and this porphyry copper formation was controlled by the highly resistive anticlines. Using 3D block Kriging interpolation method and 3D visualization techniques, we constructed a detailed 3D resistivity model of quartz diorite porphyry which shows the shape and spatial distribution of deep ore bodies. This case study can serve as a good example for future ore prospecting in and around this mining area.

  6. Modeling the formation of porphyry-copper ores

    USGS Publications Warehouse

    Ingebritsen, Steven E.

    2012-01-01

    Porphyry-copper ore systems, the source of much of the world's copper and molybdenum, form when metal-bearing fluids are expelled from shallow, degassing magmas. On page 1613 of this issue, Weis et al. (1) demonstrate that self-organizing processes focus metal deposition. Specifically, their simulation studies indicate that ores develop as consequences of dynamic variations in rock permeability driven by injection of volatile species from rising magmas. Scenarios with a static permeability structure could not reproduce key field observations, whereas dynamic permeability responses to magmatic-fluid injection localized a metal-precipitation front where enrichment by a factor of 103 could be achieved [for an overview of their numerical-simulation model CSMP++, see (2)].

  7. Porphyry Cu indicator minerals in till as an exploration tool: Example from the giant pebble porphyry Cu-Au-Mo deposit, Alaska, USA

    USGS Publications Warehouse

    Kelley, Karen D.; Eppinger, Robert G.; Lang, J.; Smith, Steven M.; Fey, David L.

    2011-01-01

    Porphyry Cu indicator minerals are mineral species in clastic sediments that indicate the presence of mineralization and hydrothermal alteration associated with porphyry Cu and associated skarn deposits. Porphyry Cu indicator minerals recovered from shallow till samples near the giant Pebble Cu-Au-Mo porphyry deposit in SW Alaska, USA, include apatite, andradite garnet, Mn-epidote, visible gold, jarosite, pyrite, and cinnabar. Sulphide minerals other than pyrite are absent from till, most likely due to the oxidation of the till. The distribution of till samples with abundant apatite and cinnabar suggest sources other than the Pebble deposit. With three exceptions, all till samples up-ice of the Pebble deposit contain 40grains/10kg) are in close proximity to smaller porphyry and skarn occurrences in the region. The distribution of Mn-epidote closely mimics the distribution of garnet in the till samples and further supports the interpretation that these minerals most likely reflect skarns associated with the porphyry deposits. All but two till samples, including those up-ice from the deposit, contain some gold grains. However, tills immediately west and down-ice of Pebble contain more abundant gold grains, and the overall number of grains decreases in the down-ice direction. Furthermore, all samples in the immediate vicinity of Pebble contain more than 65% pristine and modified grains compared to mostly re-shaped grains in distal samples. The pristine gold in till reflects short transport distances and/or liberation of gold during in-situ weathering of transported chalcopyrite grains. Jarosite is also abundant (1-2 500 grains/10kg) in samples adjacent to and up to 7 km down-ice from the deposit. Most jarosite grains are rounded and preliminary Ar/Ar dates suggest the jarosite formed prior to glaciation and it implies that a supergene cap existed over Pebble West. Assuming this interpretation is accurate, it suggests a shallow level of erosion of the Pebble deposit by

  8. Fluid evolution of Cerro Colorado Porphyry Copper Mine

    NASA Astrophysics Data System (ADS)

    Tsang, Debbie Pui Wai; Wallis, Simon

    2014-05-01

    The Cerro Colorado porphyry copper deposit is the northernmost currently active copper mine in Chile, producing 90.5kt copper per year. It belongs to one of the Paleocene to early Eocene porphyry copper deposits that are distributed along the western slope of the main Andean Cordillera in Northern Chile (Bouzari & Clark, 2002). Active commercial production began in 1994, and the estimated reserves within the supergene blanket can sustain further 12 years of copper mining. Field studies of the well-exposed geology around the mine site and the access to drilled cores that penetrate into the hypogene zone provide a good opportunity to study the temporal relationship between magmatism, hypogene and supergene ore formation of the region. The geological evolution of Cerro Colorado area can be generalized as follows. The Cretaceous Cerro Empexa Formation, consisting of a sequence of volcanic rocks, mainly andesitic lava and breccia, lahars, some ignimbrite intercalations and dacitic tuff (Charrier, Pinto & Rodrigues, 2007), was intruded by tonalitic to dioritic magma in Middle-Eocene. Magmatic activities generated brecciated rocks accompanying with different alteration zones radiate outward from the intrusion. The mineralized hypogene protore later interacted with ground water, creating the supergene blanket, which is now the principal mining target of Cerro Colorado. Several plutonic lithologies with slight but distinct compositional differences were exposed in the valleys around the mine site. The presence of these several phases of small-scale intrusions suggests the ore genesis may be related to multiple pulses of heating and associated fluid flow. Complementarily, on-site geologists have reported occurrences of early stage biotites vein cutting into phyllitic alteration zone, or across terminal stage quartz-pyrite veins in the drilled cores. These observations are direct evidences of at least two major distinct phases of fluid flow, and imply the ore mineralization

  9. Time scales of porphyry Cu deposit formation: insights from titanium diffusion in quartz

    USGS Publications Warehouse

    Mercer, Celestine N.; Reed, Mark H.; Mercer, Cameron M.

    2015-01-01

    Porphyry dikes and hydrothermal veins from the porphyry Cu-Mo deposit at Butte, Montana, contain multiple generations of quartz that are distinct in scanning electron microscope-cathodoluminescence (SEM-CL) images and in Ti concentrations. A comparison of microprobe trace element profiles and maps to SEM-CL images shows that the concentration of Ti in quartz correlates positively with CL brightness but Al, K, and Fe do not. After calibrating CL brightness in relation to Ti concentration, we use the brightness gradient between different quartz generations as a proxy for Ti gradients that we model to determine time scales of quartz formation and cooling. Model results indicate that time scales of porphyry magma residence are ~1,000s of years and time scales from porphyry quartz phenocryst rim formation to porphyry dike injection and cooling are ~10s of years. Time scales for the formation and cooling of various generations of hydrothermal vein quartz range from 10s to 10,000s of years. These time scales are considerably shorter than the ~0.6 m.y. overall time frame for each porphyry-style mineralization pulse determined from isotopic studies at Butte, Montana. Simple heat conduction models provide a temporal reference point to compare chemical diffusion time scales, and we find that they support short dike and vein formation time scales. We interpret these relatively short time scales to indicate that the Butte porphyry deposit formed by short-lived episodes of hydrofracturing, dike injection, and vein formation, each with discrete thermal pulses, which repeated over the ~3 m.y. generation of the deposit.

  10. Investigation of Stabilised Batu Pahat Soft Soil Pertaining on its CBR and Permeability Properties for Road Construction

    NASA Astrophysics Data System (ADS)

    Mohd Idrus, M. M.; Singh, J. S. M.; Musbah, A. L. A.; Wijeyesekera, D. C.

    2016-07-01

    Soil stabilization by adding materials such as cement, lime and bitumen is one of the effective methods for improving the geotechnical properties of soils [11] Nano-particle is one of the newest additives and many studies about using nano-particle in soil improvement has been done but it was given less attention when soft clay soils stabilization is concerned. To evaluate the strength characteristics of stabilized Batu Pahat soft clay, laboratory investigation on early strength gained by the stabilized soil must be conducted to formulate a suitable and economical mix design [10]. To achieve such purpose, the study examined the effect of NanoClay on the California Bearing Ratio and the Permeability of soft clay. The results gained shows that the Nano-Clay is able to increase the strength of the soft clay [9]. The California Bearing Ratio of the soil is increase significantly where the results for the highest percentage of admixture is 14.4% while the permeability of the soil decreases significantly with increasing Nano-Clay whereby the results of the highest percentage of admixture is 2.0187x10-11 m/s. After doing this research, it is proven that Nano-clay can contribute towards better soil stabilization and enhance the quality of soil as subgrade and foundation at large.

  11. Geochonology and Tectonic Significance of post-collisional porphyry in Qulong area, southeast segment of the Gangdese belt, Tibet, China

    NASA Astrophysics Data System (ADS)

    Liu, D.; Zeren, Z.; Du, C.; Feng, L.; Nima, C.; Zhang, L.

    2012-12-01

    With the collision of Indian plate and Eura-Asian plate, there developed complicated tectono-magmanism during Meso-Cenozoic in Gangdese belt, Xizang Tibet. Therefore, it resulted that plentiful tectonism and post-collision high-K calc-alkaline magmatism related to mineralization distrubted from east to west in the belt. And this is quite significant for us to do some rearch on large-scale metallogenetics, uplifting epoch and EW-striking extension during the post-collision in Xizang-Qinghai Plateau. Zircon samples from Cangrila Granodiorite-porphyry in Qulong area, Southeast of Gangdese porphyry copper belt, Xiangbeishan diorite-porphyrite and from Jiama Granite-porphyry give LA-ICPMS U-Pb ages of 16.3Ma, 14. 4Ma, and 15.4Ma, respectively, and all these ages represent the porphyries' forming ages. From barren Xiangbeishan diorite-porphyrite through intermediately mineralized Jiama Granite-porphyry to stongly mineralized Cangrila Granodiorite-porphyry, the LA-ICPMS U-Pb ages of zircon become younger and younger. According to the regional data and geochemical characteristics, these porphyries were mainly derived directly from the thickened mafic lower-crust formed in south Tibet during collision and epeirogeny. During post-collisional extension stage, for inter-earth thermal flowing, SN-striking normal faulting systems across the Tibetan orogen caused rapid rising and localization of porphyry magmas and adequately separating of massive ore-bearing fluids from the magmatic hydrothermal systems. All these data indicate that Gandese belt has experienced from post-collisional extrusion changed into intra-plate extension since Miocene. During Miocene, Gangdese belt undergone violent intraplate extension, post-collisional porphyry intrusion and paroxysmal massive mineralization of porphyry-type, and all these was controlled by deep dynamics. Key Words: Qulong area; Gangdese tectonic belt; Tibet;Zircon La-ICP-MS U-Pb dating; intra-plate extension; Image Information For CL

  12. In situ exploitation of deep set porphyry ores

    SciTech Connect

    Hard, R.A.; Harvey, W.W.; Lingane, P.J.; Park, W.C.; Redman, M.J.

    1981-09-29

    Disclosed is a method of economically exploiting deep set porphyry ore bodies of the type containing metal values such as sulfidic copper, nickel, or uranium minerals and minerals capable of absorbing copper, uranium, and nickel ions. The method involves establishing communication with the ore body through access and recovery wells and passing fluids sequentially therethrough. If necessary, thief zones of as low as 25 to 50 md in igneous rock of 1 to 5 md are prevented from distorting flow, by the injection of a polymeric solution of macromolecules with molecular weights of the order of 5 million along the entire wellbore, the higher permeability zones initially accepting the majority of the flow and being impaired at a much faster rate than the less permeable zones. In a first stage, the permeability of the leaching interval is stimulated as an ammoniated solution of sodium, potassium, or ammonium nitrate or chloride contacts calcium containing minerals to promote ion exchange, resulting in clay contraction or calcium carbonate dissolution. In a second stage, the leaching interval is primed as calcium ion is displaced with an aqueous solution of ammonium salt, a calcium sulfate scale inhibitor, and oxygen gas. In a third stage, a two-phase lixiviant comprising entrained oxygen containing bubbles and an ammoniacal leach liquor having a pH less than 10.5 and less than 1.0 mole/liter ammonia is passed through the leaching interval to solubilize copper, nickel, uranium, and other metal values.

  13. Tempo of magma degassing and the genesis of porphyry copper deposits

    NASA Astrophysics Data System (ADS)

    Chelle-Michou, Cyril; Rottier, Bertrand; Caricchi, Luca; Simpson, Guy

    2017-01-01

    Porphyry deposits are copper-rich orebodies formed by precipitation of metal sulphides from hydrothermal fluids released from magmatic intrusions that cooled at depth within the Earth’s crust. Finding new porphyry deposits is essential because they are our largest source of copper and they also contain other strategic metals including gold and molybdenum. However, the discovery of giant porphyry deposits is hindered by a lack of understanding of the factors governing their size. Here, we use thermal modelling and statistical simulations to quantify the tempo and the chemistry of fluids released from cooling magmatic systems. We confirm that typical arc magmas produce fluids similar in composition to those that form porphyry deposits and conclude that the volume and duration of magmatic activity exert a first order control on the endowment (total mass of deposited copper) of economic porphyry copper deposits. Therefore, initial magma enrichment in copper and sulphur, although adding to the metallogenic potential, is not necessary to form a giant deposit. Our results link the respective durations of magmatic and hydrothermal activity from well-known large to supergiant deposits to their metal endowment. This novel approach can readily be implemented as an additional exploration tool that can help assess the economic potential of magmatic-hydrothermal systems.

  14. Tilting history of the San Manuel-Kalamazoo porphyry system, southeastern Arizona

    USGS Publications Warehouse

    Force, E.R.; Dickinson, W.R.; Hagstrum, J.T.

    1995-01-01

    The Laramide San Manuel-Kalamazoo porphyry system of Arizona has been pivotal in concepts of both extensional tectonics and alteration-mineralization zoning. This paper reexamines the tilting history in light of new work in the region and reinterprets the geometry of the deposit. The porphyry mineralization occurs in and near an intrusion of Laramide San Manuel porphyry in Precambrian Oracle Granite. The area has an extremely complicated history of Tertiary crustal extension and fanglomerate deposition, but the blocks containing the two main fragments of the original orebody were involved in only the later parts of this history and are less tilted than other nearby blocks. Originally horizontal features of mid-Tertiary age are tilted about 30??, those of Laramide age about 35??, and those of pre-Laramide age about 45?? to the northeast. Paleomagnetism of the porphyry intrusion itself suggests tilting of about 33??. The data thus suggest that postemplacement tilt of the Laramide porphyry system was 30?? to 35?? and that virtually all of it was mid-Tertiary in age. -from Authors

  15. Tempo of magma degassing and the genesis of porphyry copper deposits

    PubMed Central

    Chelle-Michou, Cyril; Rottier, Bertrand; Caricchi, Luca; Simpson, Guy

    2017-01-01

    Porphyry deposits are copper-rich orebodies formed by precipitation of metal sulphides from hydrothermal fluids released from magmatic intrusions that cooled at depth within the Earth’s crust. Finding new porphyry deposits is essential because they are our largest source of copper and they also contain other strategic metals including gold and molybdenum. However, the discovery of giant porphyry deposits is hindered by a lack of understanding of the factors governing their size. Here, we use thermal modelling and statistical simulations to quantify the tempo and the chemistry of fluids released from cooling magmatic systems. We confirm that typical arc magmas produce fluids similar in composition to those that form porphyry deposits and conclude that the volume and duration of magmatic activity exert a first order control on the endowment (total mass of deposited copper) of economic porphyry copper deposits. Therefore, initial magma enrichment in copper and sulphur, although adding to the metallogenic potential, is not necessary to form a giant deposit. Our results link the respective durations of magmatic and hydrothermal activity from well-known large to supergiant deposits to their metal endowment. This novel approach can readily be implemented as an additional exploration tool that can help assess the economic potential of magmatic-hydrothermal systems. PMID:28079160

  16. Porphyry copper assessment of northeast Asia: Far East Russia and northeasternmost China: Chapter W in Global mineral resource assessment

    USGS Publications Warehouse

    Mihalasky, Mark J.; Ludington, Stephen; Alexeiev, Dmitriy V.; Frost, Thomas P.; Light, Thomas D.; Briggs, Deborah A.; Hammarstrom, Jane M.; Wallis, John C.; Bookstrom, Arthur A.; Panteleyev, Andre

    2015-01-01

    The database of known deposits, significant prospects, and prospects includes an inventory of mineral resources in two known porphyry copper deposits, as well as key characteristics derived from available exploration reports for 70 significant porphyry copper prospects and 86 other prospects. Resource and exploration and development activity are updated with information current through February 2013.

  17. Analysis on the Long Term Effect of Trial Test Road Constructed on Batu Pahat Soft Clay (BPSC) at Recess UTHM

    NASA Astrophysics Data System (ADS)

    Idrus, M. M. M.; Edayu, A. E.; Adnan, Z.; Ismail, B.

    2016-07-01

    The reinforcement used in soil for construction of roads on the soft clay is very important as it will determine the level of service of the road after it was built. Damage or defects on the road surface to be an indicator of the level of the road has dropped and shows the deformation of the road. For this research, an analysis has carried out on the long-term effect of trial test road constructed on Batu Pahat Soft Clay (BPSC) at RECESS UTHM. Through this research, the reinforcement using Rawell Geosynthetic Clay Liner (RGCL) was the best with the stability is 14964 N, a low flow is 2.69mm, stiffness modulus is 1766 MPa, the peak load is 739.4 N and a lower horizontal deformation which is 1.71 µm compared Woven Geotextile section and section without geotextile [1] [9]. In terms of deformation can be seen clearly from physical observations that section without geotextile suffered significant damage than others. Settlement of road can also be analyzed by a longitudinal section that plotted based on the result of leveling work. After that, settlements are more visible way on the right side of the road trial. Through lab tests conducted, it indicate that the coring samples obtained from sites of each section meets the specifications set by the Jabatan Kerja Raya (JKR) in terms of stability, flow and stiffness [1]. Through this study, a trial road built on soft soil can be used as a test site because of the uniqueness of these roads which has three different types of reinforcements.

  18. Magnetotelluric survey to characterize the Sunnyside porphyry copper system in the Patagonia Mountains, Arizona

    USGS Publications Warehouse

    Rodriguez, Brian D.; Sampson, Jay A.

    2010-01-01

    The Sunnyside porphyry copper system is part of the concealed San Rafael Valley porphyry system located in the Patagonia Mountains of Arizona. The U.S. Geological Survey is conducting a series of multidisciplinary studies as part of the Assessment Techniques for Concealed Mineral Resources project. To help characterize the size and resistivity of the mineralized area beneath overburden, a regional east-west magnetotelluric sounding profile was acquired. This is a data release report of the magnetotelluric sounding data collected along the east-west profile; no interpretation of the data is included.

  19. Audio-magnetotelluric survey to characterize the Sunnyside porphyry copper system in the Patagonia Mountains, Arizona

    USGS Publications Warehouse

    Sampson, Jay A.; Rodriguez, Brian D.

    2010-01-01

    The Sunnyside porphyry copper system is part of the concealed San Rafael Valley porphyry system located in the Patagonia Mountains of Arizona. The U.S. Geological Survey is conducting a series of multidisciplinary studies as part of the Assessment Techniques for Concealed Mineral Resources project. To help characterize the size, resistivity, and skin depth of the polarizable mineral deposit concealed beneath thick overburden, a regional east-west audio-magnetotelluric sounding profile was acquired. The purpose of this report is to release the audio-magnetotelluric sounding data collected along that east-west profile. No interpretation of the data is included.

  20. Petrogenesis and Tectonic Implications for High Ba-Sr Porphyries from South Qinling Oroganic Belt, China

    NASA Astrophysics Data System (ADS)

    Zhang, H. F.; Luo, B. J.; Shen, L. M.; Liu, Y.

    2014-12-01

    The Qinling orgenic belt resulted from collision between the North China plate and the Yangtze blocks during Triassic. In the South Qinling orogenic belt, there are lots of small porphyry bodies with area <0.5 km2. These porphyry bodies consist mainly of granodiorite porphyries in petrography. They are closely related to Cu, Mo, Au and Fe mineralization. In this presentation, we carry out an integrated study of LA-ICP-MS zircon U-Pb dating, geochemical and Sr-Nd-Hf isotopic compositions for the porphyry bodies. U-Pb zircon dating shows that they have magma crystallization ages of 145~150 Ma.They are high-potassium calc-alkaline, characterized by high Sr (up to 1300 ppm) and Ba (up to 5000 ppm). Rear earth element data for the porphyries display moderately fractionated REE patterns with (La/Yb)N=9~26 and Eu/Eu*=0.8~1.0. Geochemical characteristics of the granodiorite porphyries are good consistent with high Ba-Sr granitoids [1,2]. These granodiorite porphyries have whole-rock initial 87Sr/86Sr ratios ranging from 0.7046 to 0.7075, ɛNd (t) values ranging from - 4.6 to - 2.5, and zircon ɛHf(t) values ranging from - 2.2 to +0.8. We suggest that their magma was derived from partial melting of enriched mantle sources. The strong enrichment of Sr and Ba imply that the mantle sources could be metasomatized by fluid or melt released from subducting slab (including sediments) due to previous subduction of the Ma-Lue ocean slab at the south of the South Qinling orogenic belt. Lithospheric delamination at ~150 Ma can account for their magma generation for the porphyries. References [1] Fowler M B, Henney P J, Darbyshire D, et al. Petrogenesis of high Ba-Sr granites: the Rogart pluton, Sutherland. Journal of the Geological Society. 2001, 158: 521-534. [2] Choi S G, Rajesh V J, Seo J, et al. Petrology, geochronology and tectonic implications of Mesozoic high Ba-Sr granites in the Haemi area, Hongseong Belt, South Korea. Island Arc. 2009, 18: 266-281.

  1. Qian'echong low-F porphyry Mo deposits in the Dabie Mountains, central China

    NASA Astrophysics Data System (ADS)

    Mi, Mei; Li, Cong-ying; Sun, Wei-dong

    2015-12-01

    The Qian'echong Mo deposit is a large porphyry Mo deposit located in the northwest Dabie Mountains, central China, with proven Mo reserves of 741 Mt at 0.081%. Chondrite-normalized REE patterns of most zircon from samples QEC002, 003, 004 and 011 show HREE enrichment with distinctive positive Ce and moderately negative Eu anomalies, which are typical of magmatic zircon in porphyry deposits. Zircon grains from sample QEC001 are all hydrothermal in origin, whereas there are only several hydrothermal zircons in the other samples. The Ti-in-zircon thermometer yields temperatures of 700-740 °C for the magmatic zircon. The Ce4 +/Ce3 + calculated from the Ce anomaly is a sensitive and robust indicator of magmatic oxidation status. Magmatic zircon have Ce4 +/Ce3 + and (Eu/Eu*)N ratios ranging between 10-577 and 0.2-1.3, respectively. Compared to the Shapinggou deposit (Climax type) also in the Dabie Mountains, the Qian'echong zircon has systematically lower Ce4 +/Ce3 +. Apatite from the Qian'echong deposit belongs to the F-apatite variety, with fluorine concentrations varying between 2.13-4.50% and Cl concentrations between 0.01-0.28%. Whole rock samples of the porphyry from the Qian'echong deposit have F contents of 360-1230 ppm. The porphyry intrusion is consistently associated with calc-alkaline granitic to granodioritic porphyries, with lower F, Nb, and Ta concentrations, and systematically lower Mo contents than the Climax-type deposits. All these characteristics are similar to other low-F porphyry Mo deposits along the eastern Pacific margin. Fluorine is mainly hosted in phengite during plate subduction, which may decompose far beneath the surface of the subduction zone. Therefore, high F deposits may be interpreted as locating the farthermost position reached by the subducting slab. Nevertheless, the F contents of the Qian'echong deposit is much higher than in adjacent barren granites, and may have incorporated additional F from the subduction slab. Given that the

  2. Recognition of the geologic framework of porphyry deposits on ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Wilson, J. C. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. Photointerpretation methods have been most successfully applied in the less vegetated test sites where several previously unknown geologic features have been recognized and known ones extended. Northwest mid-Tertiary faults in the ELY, Nevada area are observed to offset north-trending ranges and abruptly terminate older Mesozoic structures. In the Ray, Arizona area the observed patterns of fault and fracture systems appear to be related to the locations of known porphyry copper deposits. In the Tanacross, Alaska area a number of regional circular features observed may represent near surface intrusions and, therefore, permissive environments for copper porphyries.

  3. Origin of the Lengshuigou porphyry-skarn Cu deposit in the Zha-Shan district, South Qinling, central China, and implications for differences between porphyry Cu and Mo deposits

    NASA Astrophysics Data System (ADS)

    Xie, Guiqing; Mao, Jingwen; Wang, Ruiting; Meng, Deming; Sun, Jia; Dai, Junzhi; Ren, Tao; Li, Jianbi; Zhao, Haijie

    2016-10-01

    Porphyry Cu and Mo deposits are two economically important types of metal deposits worldwide, but factors controlling their difference remain enigmatic. Compared with the well-studied large porphyry Mo province in the south margin of the North China Block (S-NCB), the origin of newly discovered porphyry Cu deposits in the South Qinling (SQB) is poorly constrained. Integrated zircon LA-ICPMS U-Pb and molybdenite Re-Os ages and geological evidence indicate three stages of magmatism at Lengshuigou: (1) late Neoproterozoic (718 to 704 Ma) quartz diorite + albitite + granite association during the pre-ore stage, (2) 146 to 145 Ma granodiorite porphyry during the syn-ore stage, and (3) 145 Ma granite porphyry during the post-ore stage. Elemental and Sr-Nd isotopic evidence provide important constraints on their magma source. Pre-ore Neoproterozoic quartz diorite + albitite + granite was derived by re-melting of a mixture of crustal and juvenile mantle materials, and stronger fractional crystallization was involved in these ore-hosting intrusions than in contemporary granitoids hosted in the Douling Group. Syn-ore granodiorite porphyry was derived from mantle-derived magma with contributions from different proportions of crustal components. Post-ore granite porphyry was derived mainly from a crustal source. Nearly contemporaneous porphyry Cu and Mo systems were identified in Qinling Province, including the 147-139 Ma porphyry Mo systems in the S-NCB and 150-146 Ma porphyry Cu systems in the SQB. Granitic stocks related to porphyry Cu systems in the SQB are characterized by moderate SiO2 contents (58.01-69.07 %) and less radiogenic Nd-Hf isotopes (ɛNd(t) = -3.8 to -6.3, ɛHf(t) = -4.5 to +1.6), whereas the granitic stocks related to porphyry Mo deposits in the S-NCB have high SiO2 concentrations (64.00-76.00 %) and more radiogenic Nd-Hf isotopes (ɛNd(t) = -18.0 to -11.6, ɛHf(t) = -26.3 to -13.5). In addition, molybdenite from the Chigou and Lengshuigou porphyry Cu

  4. Stochastic modelling of deep magmatic controls on porphyry copper deposit endowment.

    PubMed

    Chiaradia, Massimo; Caricchi, Luca

    2017-03-15

    Porphyry deposits, our main source of copper and of significant amounts of Mo, Re and Au, form at convergent margins in association with intermediate-felsic magmas. Although it is accepted that copper is transported and precipitated by fluids released by these magmas, the magmatic processes leading to the formation of economic deposits remain elusive. Here we perform Monte Carlo petrological and geochemical modelling to quantitatively link crustal magmatic processes and the geochemical signatures of magmas (i.e., Sr/Y) to the formation of porphyry Cu deposits of different sizes. Our analysis shows that economic deposits (particularly the largest ones) may only form in association with magma accumulated in the lower-middle crust (P > ~0.5 GPa) during ≥2-3 Ma, and subsequently transferred to and degassed in the upper crust over periods of up to ~2.0 Ma. Magma accumulation and evolution at shallower depths (<~0.4 GPa) dramatically reduces the potential of magmatic systems to produce economic deposits. Our modelling also predicts the association of the largest porphyry deposits with a specific Sr/Y interval (~100 ± 50) of the associated magmatic rocks, which is virtually identical to the range measured in giant porphyry copper deposits.

  5. Porphyry copper assessment of western Central Asia: Chapter N in Global mineral resource assessment

    USGS Publications Warehouse

    Berger, Byron R.; Mars, John L.; Denning, Paul D.; Phillips, Jeffrey D.; Hammarstrom, Jane M.; Zientek, Michael L.; Dicken, Connie L.; Drew, Lawrence J.; with contributions from Alexeiev, Dmitriy; Seltmann, Reimar; Herrington, Richard J.

    2014-01-01

    Detailed descriptions of each permissive tract, including the rationales for delineation and assessment, are given in appendixes, along with a geographic information system (GIS) that includes permissive tract boundaries, point locations of known porphyry copper deposits and significant occurrences, and hydrothermal alteration data based on analysis of remote sensing data.

  6. Stochastic modelling of deep magmatic controls on porphyry copper deposit endowment

    PubMed Central

    Chiaradia, Massimo; Caricchi, Luca

    2017-01-01

    Porphyry deposits, our main source of copper and of significant amounts of Mo, Re and Au, form at convergent margins in association with intermediate-felsic magmas. Although it is accepted that copper is transported and precipitated by fluids released by these magmas, the magmatic processes leading to the formation of economic deposits remain elusive. Here we perform Monte Carlo petrological and geochemical modelling to quantitatively link crustal magmatic processes and the geochemical signatures of magmas (i.e., Sr/Y) to the formation of porphyry Cu deposits of different sizes. Our analysis shows that economic deposits (particularly the largest ones) may only form in association with magma accumulated in the lower-middle crust (P > ~0.5 GPa) during ≥2–3 Ma, and subsequently transferred to and degassed in the upper crust over periods of up to ~2.0 Ma. Magma accumulation and evolution at shallower depths (<~0.4 GPa) dramatically reduces the potential of magmatic systems to produce economic deposits. Our modelling also predicts the association of the largest porphyry deposits with a specific Sr/Y interval (~100 ± 50) of the associated magmatic rocks, which is virtually identical to the range measured in giant porphyry copper deposits. PMID:28295045

  7. Generation of porphyry copper deposits by gas-brine reaction in volcanic arcs

    NASA Astrophysics Data System (ADS)

    Blundy, J.; Mavrogenes, J.; Tattitch, B.; Sparks, S.; Gilmer, A.

    2015-03-01

    Porphyry copper deposits, that is, copper ore associated with hydrothermal fluids rising from a magma chamber, supply 75% of the world's copper. They are typically associated with intrusions of magma in the crust above subduction zones, indicating a primary role for magmatism in driving mineralization. However, it is not clear that a single, copper-rich magmatic fluid could trigger both copper enrichment and the subsequent precipitation of sulphide ore minerals within a zone of hydrothermally altered rock. Here we draw on observations of modern subduction zone volcanism to propose an alternative process for porphyry copper formation. We suggest that copper enrichment initially involves metalliferous, magmatic hyper-saline liquids, or brines, that exsolve from large, magmatic intrusions assembled in the shallow crust over tens to hundreds of thousands of years. In a subsequent step, sulphide ore precipitation is triggered by the interaction of the accumulated brines with sulphur-rich gases, liberated in short-lived bursts from the underlying mafic magmas. We use high-temperature and high-pressure laboratory experiments to simulate such gas-brine interactions. The experiments yield copper-iron sulphide minerals and hydrogen chloride gas at magmatic temperatures of 700-800 °C, with textural and chemical characteristics that resemble those in porphyry copper deposits. We therefore conclude that porphyry copper ore forms in a two-stage process of brine enrichment followed by gas-induced precipitation.

  8. Stochastic modelling of deep magmatic controls on porphyry copper deposit endowment

    NASA Astrophysics Data System (ADS)

    Chiaradia, Massimo; Caricchi, Luca

    2017-03-01

    Porphyry deposits, our main source of copper and of significant amounts of Mo, Re and Au, form at convergent margins in association with intermediate-felsic magmas. Although it is accepted that copper is transported and precipitated by fluids released by these magmas, the magmatic processes leading to the formation of economic deposits remain elusive. Here we perform Monte Carlo petrological and geochemical modelling to quantitatively link crustal magmatic processes and the geochemical signatures of magmas (i.e., Sr/Y) to the formation of porphyry Cu deposits of different sizes. Our analysis shows that economic deposits (particularly the largest ones) may only form in association with magma accumulated in the lower-middle crust (P > ~0.5 GPa) during ≥2–3 Ma, and subsequently transferred to and degassed in the upper crust over periods of up to ~2.0 Ma. Magma accumulation and evolution at shallower depths (<~0.4 GPa) dramatically reduces the potential of magmatic systems to produce economic deposits. Our modelling also predicts the association of the largest porphyry deposits with a specific Sr/Y interval (~100 ± 50) of the associated magmatic rocks, which is virtually identical to the range measured in giant porphyry copper deposits.

  9. HUNTER-FRYINGPAN WILDERNESS AND PORPHYRY MOUNTAIN WILDERNESS STUDY AREA, COLORADO.

    USGS Publications Warehouse

    Ludington, Steve; Ellis, Clarence E.

    1984-01-01

    A mineral survey of the Hunter-Fryingpan Wilderness and the Porphyry Mountain Wilderness study area, Colorado was conducted. Substantiated gold and silver resource potential was identified in one area and a surrounding area is judged to have probable mineral-resource potential for gold and silver. No other mineral or energy resources were identified in the study.

  10. Lead-isotopic signatures of porphyry copper deposits in oceanic and continental settings, Colombian Andes

    NASA Astrophysics Data System (ADS)

    Sillitoe, R. H.; Hart, S. R.

    1984-10-01

    Three discrete sub-belts of porphyry copper-type mineralization are recognized in the Colombian Andes: a western Eocene sub-belt, an eastern Jurassic to early Cretaceous sub-belt and, between them, a central Miocene sub-belt. The western sub-belt is part of an oceanic domain constituted by oceanic crust and overlying immature island-arc rocks, the eastern sub-belt is within a continental domain underlain by the leading edge of the Guayana shield, and the central sub-belt spans the faulted boundary between them. The thicker continental crust includes important granulitic rocks which crop out locally, as in the vicinity of the Mocoa porphyry copper deposit. Pb-isotopic ratios were determined for pyrite samples collected from 6 porphyry copper centers, 3 in the western sub-belt, 2 in the eastern sub-belt, and one in the central sub-belt. Ratios fall into 3 discrete populations: the most radiogenic values represent the western sub-belt, the least radiogenic represent the eastern sub-belt, and an intermediate value corresponds to the central sub-belt. Ratios therefore become progressively less radiogenic from the western oceanic domain to the eastern cratonic domain. Comparison of the Pb-isotopic ratios with those given in the literature for possible source materials for Colombian porphyry copper leads enables the subcontinental mantle wedge, subducted oceanic crust and subducted metalliferous sediments to be discounted as principal sources. The relatively radiogenic signatures of 5 of the porphyry copper centers appear to be broadly compatible with either a subducted pelagic sediment source or an upper continental crust source, whereas the sixth center, Mocoa, is characterized by a distinctly less radiogenic 206Pb /204Pb ratio. An admixture of a relatively small percentage of non-radiogenic Pb from granulitic material in the upper crust with the more radiogenic Pb typical of the western sub-belt centers could account for the Mocoa data. Because much of the upper

  11. Rapid thermal rejuvenation of high-crystallinity magma linked to porphyry copper deposit formation; evidence from the Koloula Porphyry Prospect, Solomon Islands

    NASA Astrophysics Data System (ADS)

    Tapster, S.; Condon, D. J.; Naden, J.; Noble, S. R.; Petterson, M. G.; Roberts, N. M. W.; Saunders, A. D.; Smith, D. J.

    2016-05-01

    Magmas containing the components needed to form porphyry copper deposits are relatively common within arcs, yet mineralising events are uncommon within the long-lived magmatic systems that host them. Understanding what causes the transition from barren to productive intrusions is critical to the development of conceptual deposit models. We have constrained the tempo of pre- and syn-mineralisation magmatic events in relationship to the thermal evolution of the plutonic body that underlies one of the world's youngest exposed plutonic-porphyry systems, the Inamumu Zoned Pluton, Koloula Porphyry Prospect, Solomon Islands. High precision ID-TIMS U-Pb dates of texturally and chemically characterised zircons indicate pluton emplacement over <150 kyr was superseded after ca. 50 kyr by two discrete episodes of mineralising porphyritic melt emplacement. Their associated hydrothermal systems initiated within ca. 30 kyrs of each other. Zircon populations within evolved intrusions contain resorbed cores that were recycled from the deeper magmatic system, yet their youngest dates are statistically indistinguishable from those yielded by crystals lacking resorption. Comparisons of Ti-in-zircon proxy temperatures, modelled zircon saturation temperatures and temperature-crystallinity relationships suggest that prior to being heated and emplaced within the shallow level pluton, magmas were stored at depth in a high-crystallinity (>50% crystals) state, past the point of rheological lock-up. We estimate that thermal rejuvenation of the deeper high-crystallinity magma and generation of a mobile melt fraction may have occurred ≤10 kyr before its transport and emplacement within the porphyry environment. The underlying pluton likely cooled and returned to high-crystallinity states prior to subsequent remobilisation-emplacement events. Titanium-in-zircon geothermometry and whole-rock geochemistry suggest pre-mineralisation intrusions were remobilised by mixing of a silicic magma with a

  12. Porphyry copper deposit tract definition - A global analysis comparing geologic map scales

    USGS Publications Warehouse

    Raines, G.L.; Connors, K.A.; Chorlton, L.B.

    2007-01-01

    Geologic maps are a fundamental data source used to define mineral-resource potential tracts for the first step of a mineral resource assessment. Further, it is generally believed that the scale of the geologic map is a critical consideration. Previously published research has demonstrated that the U.S. Geological Survey porphyry tracts identified for the United States, which are based on 1:500,000-scale geology and larger scale data and published at 1:1,000,000 scale, can be approximated using a more generalized 1:2,500,000-scale geologic map. Comparison of the USGS porphyry tracts for the United States with weights-of-evidence models made using a 1:10,000,000-scale geologic map, which was made for petroleum applications, and a 1:35,000,000-scale geologic map, which was created as context for the distribution of porphyry deposits, demonstrates that, again, the USGS US porphyry tracts identified are similar to tracts defined on features from these small scale maps. In fact, the results using the 1:35,000,000-scale map show a slightly higher correlation with the USGS US tract definition, probably because the conceptual context for this small-scale map is more appropriate for porphyry tract definition than either of the other maps. This finding demonstrates that geologic maps are conceptual maps. The map information shown in each map is selected and generalized for the map to display the concepts deemed important for the map maker's purpose. Some geologic maps of small scale prove to be useful for regional mineral-resource tract definition, despite the decrease in spatial accuracy with decreasing scale. The utility of a particular geologic map for a particular application is critically dependent on the alignment of the intention of the map maker with the application. ?? International Association for Mathematical Geology 2007.

  13. Porphyry copper deposits of the world: database, map, and grade and tonnage models

    USGS Publications Warehouse

    Singer, Donald A.; Berger, Vladimir Iosifovich; Moring, Barry C.

    2005-01-01

    Mineral deposit models are important in exploration planning and quantitative resource assessments for two reasons: (1) grades and tonnages among deposit types are significantly different, and (2) many types occur in different geologic settings that can be identified from geologic maps. Mineral deposit models are the keystone in combining the diverse geoscience information on geology, mineral occurrences, geophysics, and geochemistry used in resource assessments and mineral exploration. Too few thoroughly explored mineral deposits are available in most local areas for reliable identification of the important geoscience variables or for robust estimation of undiscovered deposits-thus we need mineral-deposit models. Globally based deposit models allow recognition of important features because the global models demonstrate how common different features are. Well-designed and -constructed deposit models allow geologists to know from observed geologic environments the possible mineral deposit types that might exist, and allow economists to determine the possible economic viability of these resources in the region. Thus, mineral deposit models play the central role in transforming geoscience information to a form useful to policy makers. The foundation of mineral deposit models is information about known deposits-the purpose of this publication is to make this kind of information available in digital form for porphyry copper deposits. This report is an update of an earlier publication about porphyry copper deposits. In this report we have added 84 new porphyry copper deposits and removed 12 deposits. In addition, some errors have been corrected and a number of deposits have had some information, such as grades, tonnages, locations, or ages revised. This publication contains a computer file of information on porphyry copper deposits from around the world. It also presents new grade and tonnage models for porphyry copper deposits and for three subtypes of porphyry copper

  14. Porphyry copper assessment of the Tibetan Plateau, China: Chapter F in Global mineral resource assessment

    USGS Publications Warehouse

    Ludington, Steve; Hammarstrom, Jane M.; Robinson,, Gilpin R.; Mars, John L.; Miller, Robert J.

    2012-01-01

    Assessment results, presented in tables and graphs, show mean expected amounts of metal and rock in undiscovered deposits at different quantile levels, as well as the arithmetic mean for each tract. This assessment estimated a mean of 39 undiscovered porphyry copper deposits within the assessed permissive tracts on the Tibetan Plateau. This represents nearly four times the number of known deposits (11) already discovered. Predicted mean (arithmetic) resources that could be associated with the undiscovered deposits are about 145,000,000 t of copper and about 4,900 t of gold, as well as byproduct molybdenum and silver. Reliable reports of the identified resources in the 11 known deposits total about 27,000,000 t of copper and about 800 t of gold. Therefore, based on the assessments of undiscovered Tibetan Plateau resources in this report, about six times as much copper may occur in undiscovered porphyry copper deposits as has been identified to date.

  15. Geochemistry of magnetite from porphyry Cu and skarn deposits in the southwestern United States

    USGS Publications Warehouse

    Nadoll, Patrick; Mauk, Jeffrey L.; LeVeille, Richard A.; Koenig, Alan E.

    2015-01-01

    A combination of petrographic observations, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and statistical data exploration was used in this study to determine compositional variations in hydrothermal and igneous magnetite from five porphyry Cu–Mo and skarn deposits in the southwestern United States, and igneous magnetite from the unmineralized, granodioritic Inner Zone Batholith, Japan. The most important overall discriminators for the minor and trace element chemistry of magnetite from the investigated porphyry and skarn deposits are Mg, Al, Ti, V, Mn, Co, Zn, and Ga—of these the elements with the highest variance for (I) igneous magnetite are Mg, Al, Ti, V, Mn, Zn, for (II) hydrothermal porphyry magnetite are Mg, Ti, V, Mn, Co, Zn, and for (III) hydrothermal skarn magnetite are Mg, Ti, Mn, Zn, and Ga. Nickel could only be detected at levels above the limit of reporting (LOR) in two igneous magnetites. Equally, Cr could only be detected in one igneous occurrence. Copper, As, Mo, Ag, Au, and Pb have been reported in magnetite by other authors but could not be detected at levels greater than their respective LORs in our samples. Comparison with the chemical signature of igneous magnetite from the barren Inner Zone Batholith, Japan, suggests that V, Mn, Co, and Ga concentrations are relatively depleted in magnetite from the porphyry and skarn deposits. Higher formation conditions in combination with distinct differences between melt and hydrothermal fluid compositions are reflected in Al, Ti, V, and Ga concentrations that are, on average, higher in igneous magnetite than in hydrothermal magnetite (including porphyry and skarn magnetite). Low Ti and V concentrations in combination with high Mn concentrations are characteristic features of magnetite from skarn deposits. High Mg concentrations (<1,000 ppm) are characteristic for magnetite from magnesian skarn and likely reflect extensive fluid/rock interaction. In porphyry deposits

  16. Geochemistry of magnetite from porphyry Cu and skarn deposits in the southwestern United States

    NASA Astrophysics Data System (ADS)

    Nadoll, Patrick; Mauk, Jeffrey L.; Leveille, Richard A.; Koenig, Alan E.

    2015-04-01

    A combination of petrographic observations, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and statistical data exploration was used in this study to determine compositional variations in hydrothermal and igneous magnetite from five porphyry Cu-Mo and skarn deposits in the southwestern United States, and igneous magnetite from the unmineralized, granodioritic Inner Zone Batholith, Japan. The most important overall discriminators for the minor and trace element chemistry of magnetite from the investigated porphyry and skarn deposits are Mg, Al, Ti, V, Mn, Co, Zn, and Ga—of these the elements with the highest variance for (I) igneous magnetite are Mg, Al, Ti, V, Mn, Zn, for (II) hydrothermal porphyry magnetite are Mg, Ti, V, Mn, Co, Zn, and for (III) hydrothermal skarn magnetite are Mg, Ti, Mn, Zn, and Ga. Nickel could only be detected at levels above the limit of reporting (LOR) in two igneous magnetites. Equally, Cr could only be detected in one igneous occurrence. Copper, As, Mo, Ag, Au, and Pb have been reported in magnetite by other authors but could not be detected at levels greater than their respective LORs in our samples. Comparison with the chemical signature of igneous magnetite from the barren Inner Zone Batholith, Japan, suggests that V, Mn, Co, and Ga concentrations are relatively depleted in magnetite from the porphyry and skarn deposits. Higher formation conditions in combination with distinct differences between melt and hydrothermal fluid compositions are reflected in Al, Ti, V, and Ga concentrations that are, on average, higher in igneous magnetite than in hydrothermal magnetite (including porphyry and skarn magnetite). Low Ti and V concentrations in combination with high Mn concentrations are characteristic features of magnetite from skarn deposits. High Mg concentrations (<1,000 ppm) are characteristic for magnetite from magnesian skarn and likely reflect extensive fluid/rock interaction. In porphyry deposits

  17. Porphyry copper assessment of Southeast Asia and Melanesia: Chapter D in Global mineral resource assessment

    USGS Publications Warehouse

    Hammarstrom, Jane M.; Bookstrom, Arthur A.; Dicken, Connie L.; Drenth, Benjamin J.; Ludington, Steve; Robinson,, Gilpin R.; Setiabudi, Bambang Tjahjono; Sukserm, Wudhikarn; Sunuhadi, Dwi Nugroho; Wah, Alexander Yan Sze; Zientek, Michael L.

    2013-01-01

    This assessment includes an overview of the assessment results with summary tables. Detailed descriptions of each tract are included in appendixes, with estimates of numbers of undiscovered deposits, and probabilistic estimates of amounts of copper, molybdenum, gold, and silver that could be contained in undiscovered deposits for each permissive tract. A geographic information system (GIS) that accompanies the report includes tract boundaries and a database of known porphyry copper deposits and significant prospects.

  18. Geology and mineralogy of the Alakha spodumene granite porphyry deposit, Gorny Altai, Russia

    NASA Astrophysics Data System (ADS)

    Annikova, I. Yu.; Vladimirov, A. G.; Smirnov, S. Z.; Gavryushkina, O. A.

    2016-09-01

    The Alakha lithium-tantalum deposit in the southern Altai, Russia, is represented by a stock of spodumene-bearing granite porphyry localized in the Kalba-Narym-Koktogai lithium-tantalum rare-metal granitic belt, unique in extent (more than 1000 km). This belt is a part of the Altai accretionary-collisional system. Judging from forecasting, the Alakha deposit can be regarded as an uneroded proxy of a pegmatite body both in dimensions and mean Li2O and Ta2O5 contents (0.98 wt % and 114 ppm, respectively); however, the oregenerating potential of this deposit remains insufficiently studied and had not yet been claimed. In this paper, we attempt to fill this gap with a detailed mineralogical study, which allows us to provide insights into the crystallization of Li-bearing high-silicic magma and redistribution of components during magmatic and postmagmatic processes. Accessory mineral assemblages in muscovite-spodumene-K-feldspar granite porphyry and muscovite albitite—the main petrographic rock varieties of the Alakha stock—turned out to be almost identical. A significant similarity in the chemistry of major rock-forming minerals is established for spodumene granite porphyry of the Alakha stock and spodumene pegmatites from large deposits, which makes it possible to suggest that they are close in the petrogenetic mechanism of their formation. The mineral assemblages of muscovite albitite in the apical portion of the Alakha stock are connected by gradual transition with those of spodumene granite porphyry. Such a transition is caused by postmagmatic metasomatic alteration of the latter.

  19. Tectonic environments of South American porphyry copper magmatism through time revealed by spatiotemporal data mining

    NASA Astrophysics Data System (ADS)

    Butterworth, N.; Steinberg, D.; Müller, R. D.; Williams, S.; Merdith, A. S.; Hardy, S.

    2016-12-01

    Porphyry ore deposits are known to be associated with arc magmatism on the overriding plate at subduction zones. While general mechanisms for driving magmatism are well established, specific subduction-related parameters linking episodes of ore deposit formation to specific tectonic environments have only been qualitatively inferred and have not been formally tested. We develop a four-dimensional approach to reconstruct age-dated ore deposits, with the aim of isolating the tectonomagmatic parameters leading to the formation of copper deposits during subduction. We use a plate tectonic model with continuously closing plate boundaries, combined with reconstructions of the spatiotemporal distribution of the ocean floor, including subducted portions of the Nazca/Farallon plates. The models compute convergence rates and directions, as well as the age of the downgoing plate through time. To identify and quantify tectonic parameters that are robust predictors of Andean porphyry copper magmatism and ore deposit formation, we test two alternative supervised machine learning methods; the "random forest" (RF) ensemble and "support vector machines" (SVM). We find that a combination of rapid convergence rates ( 100 km/Myr), subduction obliquity of 15°, a subducting plate age between 25-70 Myr old, and a location far from the subducting trench boundary (>2000 km) represents favorable conditions for porphyry magmatism and related ore deposits to occur. These parameters are linked to the availability of oceanic sediments, the changing small-scale convection around the subduction zone, and the availability of the partial melt in the mantle wedge. When coupled, these parameters could influence the genesis and exhumation of porphyry copper deposits.

  20. Isotopic and geochemical studies of a Pliocene porphyry-Mo system, Rico, Colorado

    SciTech Connect

    Wareham, C.D.

    1991-01-01

    The historic mining district of Rico in southern Colorado Mineral Belt contains a Pliocene porphyry-Mo deposit and peripheral epithermal Pb-Zn-Ag deposits, and hot-springs. The porphyry-Mo mineralization is confined almost exclusively to Precambrian greenstone. The epithermal mineralization is hosted by a Paleozoic and Mesozoic sequence dominated by carbonates, but containing evaporites. The system is geologically complex and focused on a resurgent dome which is cored by a horst of Precambrian strata, and cut by reactivated Precambrian basement shears. The shears have controlled the emplacement of the Laramide and Pliocene granitoids in area. The mineralization is associated with more evolved members of the latter suite. Sr-Nd-Pb-O isotope and minor element data on the granitoid intrusions indicate that they are not simply differentiates of mantle magmas. However, Nd model ages indicate that they are not purely remelts of 1800Ma Precambrian crust. Realistically it is impossible to quantify the relative proportions of crust and mantle material involved in the genesis of the intrusions. Notwithstanding this, the Rico granitoids are isotopically distinct from those associated with Climax-type porphyry-Mo deposits in Colorado. Sd-Nd-Pb isotope and trace element data on a lamprophyre suite in the area suggest two episodes of mafic magmatism; a period whereby the source was predominantly, OIB-type, asthenospheric mantle. [sigma][sup 34]S data and ore deposit paragenesis indicate that the sulphide S has an igneous origin and that the sulphate S was derived by mobilization of Pennsylvanian evaporites. Modelling of the S isotopic data indicates a common S source for the epithermal and porphyry mineralization. The sulphate and sulphide S reservoirs remained essentially decoupled during mineralization. [sigma][sup 34]C data are compatible with the hydrothermal C having been derived by the dissolution and re-precipitation of host sequence carbonate.

  1. Timing and duration of hydrothermal activity at the Los Bronces porphyry cluster: an update

    NASA Astrophysics Data System (ADS)

    Deckart, K.; Silva, W.; Spröhnle, C.; Vela, I.

    2014-06-01

    New geochronological data from the Los Bronces cluster of the Río Blanco-Los Bronces mega-porphyry Cu-Mo district establish a wide range of magmatism, hydrothermal alteration, and mineralization ages, both in terms of areal extent and time. The northern El Plomo and southernmost Los Piches exploration areas contain the oldest barren porphyritic intrusions with U-Pb ages of 10.8 ± 0.1 Ma and 13.4 ± 0.1 Ma, respectively. A hypabyssal barren intrusion adjacent northwesterly to the main pit area yields a slightly younger age of 10.2 ± 0.3 Ma (San Manuel sector, U-Pb), whereas in the Los Bronces (LB) open-pit area, the present day mineral extraction zone, porphyries range from 8.49 to 6.02 Ma (U-Pb). Hydrothermal biotite and sericite ages are up to 0.5 Ma younger but consistent with the cooling of the corresponding intrusion events of each area. Two quartz-molybdenite B-type veins from the LB open pit have Re-Os molybdenite ages of 5.65 ± 0.03 Ma and 5.35 ± 0.03 Ma consistent with published data for the contiguous Río Blanco cluster. The San Manuel exploration area within the Los Bronces cluster, located about 1.5-2 km southeast of the open-pit extraction zone, shows both the oldest hydrothermal biotite (7.70 ± 0.07 Ma; 40Ar/39Ar) and breccia cement molybdenite ages (8.36 ± 0.06 Ma; Re-Os) registered in the entire Río Blanco-Los Bronces district. These are also older than those reported from the El Teniente porphyry Cu(-Mo) deposit, suggesting that mineralization in the late Miocene to early Pliocene porphyry belt of Central Chile commenced 2 Ma before the previously accepted age of 6.3 Ma.

  2. Mine drainage water from the Sar Cheshmeh porphyry copper mine, Kerman, IR Iran.

    PubMed

    Shahabpour, J; Doorandish, M

    2008-06-01

    This paper presents the results of a study on stream and mine waters in the area of one of the world largest porphyry copper deposit located in the southeastern Iran, the Sar Cheshmeh porphyry copper mine. Trace metals are present as adsorption on Fe and Mn oxide and hydroxide particles, as sulfate, simple metal ions, and scarcely as adsorption on clay particles and hydrous aluminium oxides. Mean pH decreases and the mean concentration of trace elements, EC and SO4(2-) increases from the maximum discharge period (MXDP) during snow melt run off (May), through the moderate discharge period (MDDP; March and July) to the minimum discharge period (MNDP; September). Water samples have sulfatic character essentially, however, from the MNDP through the MDDP towards the MXDP they show a bicarbonate tendency. This study indicates that the surface waters draining the Sar Cheshmeh open pit have a higher pH and lower concentration of trace metals compared with some other porphyry copper deposits.

  3. Why large porphyry Cu deposits like high Sr/Y magmas?

    PubMed Central

    Chiaradia, Massimo; Ulianov, Alexey; Kouzmanov, Kalin; Beate, Bernardo

    2012-01-01

    Porphyry systems supply most copper and significant gold to our economy. Recent studies indicate that they are frequently associated with high Sr/Y magmatic rocks, but the meaning of this association remains elusive. Understanding the association between high Sr/Y magmatic rocks and porphyry-type deposits is essential to develop genetic models that can be used for exploration purposes. Here we present results on a Pleistocene volcano of Ecuador that highlight the behaviour of copper in magmas with variable (but generally high) Sr/Y values. We provide indirect evidence for Cu partitioning into a fluid phase exsolved at depths of ~15 km from high Sr/Y (>70) andesitic magmas before sulphide saturation. This lends support to the hypothesis that large amounts of Cu- and S-bearing fluids can be accumulated into and released from a long-lived high Sr/Y deep andesitic reservoir to a shallower magmatic-hydrothermal system with the potential of generating large porphyry-type deposits. PMID:23008750

  4. Why large porphyry Cu deposits like high Sr/Y magmas?

    PubMed

    Chiaradia, Massimo; Ulianov, Alexey; Kouzmanov, Kalin; Beate, Bernardo

    2012-01-01

    Porphyry systems supply most copper and significant gold to our economy. Recent studies indicate that they are frequently associated with high Sr/Y magmatic rocks, but the meaning of this association remains elusive. Understanding the association between high Sr/Y magmatic rocks and porphyry-type deposits is essential to develop genetic models that can be used for exploration purposes. Here we present results on a Pleistocene volcano of Ecuador that highlight the behaviour of copper in magmas with variable (but generally high) Sr/Y values. We provide indirect evidence for Cu partitioning into a fluid phase exsolved at depths of ~15 km from high Sr/Y (>70) andesitic magmas before sulphide saturation. This lends support to the hypothesis that large amounts of Cu- and S-bearing fluids can be accumulated into and released from a long-lived high Sr/Y deep andesitic reservoir to a shallower magmatic-hydrothermal system with the potential of generating large porphyry-type deposits.

  5. Age of Supergene oxidation and enrichment in the chilean porphyry copper province

    USGS Publications Warehouse

    Sillitoe, R.H.; McKee, E.H.

    1996-01-01

    Twenty-five samples of supergene alunite collected from deeply developed supergene profiles in porphyry copper deposits and prospects between latitudes 20?? and 27?? S in northern Chile yield K/Ar ages ranging from about 34 to 14 Ma. Therefore supergene oxidation and enrichment processes were active from the early Oligocene to the middle Miocene, a minimum of 20 m.y. Supergene activity at individual deposits lasted for at least 0.4 to 6.2 m.y. The early Oligocene supergene activity affected deposits in the Paleocene porphyry copper belt, whereas early and middle Miocene supergene processes are documented in the Early Cretaceous, Paleocene, and late Eocene to early Oligocene porphyry copper belts. Middle Miocene oxidation also affected the oldest epithermal gold-silver deposits in the Maricunga belt farther east. Supergene activity commenced no less than 11 m.y. after generation of each porphyry copper deposit because of the time required to unroof the copper-bearing parts of the system. Supergene activity throughout northern Chile ceased at -14 Ma. The geologic features of deposits and prospects and their morphotectonic positions, present latitudes, and present elevations display no obvious correlations with the supergene chronology. Exploration for major cumulative enrichment blankets should not be carried out either beneath thick sequences of piedmont gravels (?? ignimbrites) of Oligocene through middle Miocene age unless their accumulation is demonstrably late in the documented history of supergene activity, or in porphyry copper provinces, such as those of central Chile and northwestern Argentina, which formed after ??? 14 Ma. The uplift responsible for efficient cumulative copper enrichment is difficult to correlate convincingly with the brief pulses of compressive tectonism postulated for northern Chile and contiguous areas unless their effects were much more prolonged. Intensifying aridity is confirmed as the likely reason for the cessation of supergene

  6. Porphyry Cu-Au and associated polymetallic Fe-Cu-Au deposits in the Beiya Area, western Yunnan Province, south China

    USGS Publications Warehouse

    Xu, X.-W.; Cai, X.-P.; Xiao, Q.-B.; Peters, S.G.

    2007-01-01

    The Alkaline porphyries in the Beiya area are located east of the Jinshajiang suture, as part of a Cenozoic alkali-rich porphyry belt in western Yunnan. The main rock types include quartz-albite porphyry, quartz-K-feldspar porphyry and biotite-K-feldspar porphyry. These porphyries are characterised by high alkalinity [(K2O + Na2O)% > 10%], high silica (SiO2% > 65%), high Sr (> 400??ppm) and 87Sr/86Sr (> 0.706)] ratio and were intruded at 65.5??Ma, between 25.5 to 32.5??Ma, and about 3.8??Ma, respectively. There are five main types of mineral deposits in the Beiya area: (1) porphyry Cu-Au deposits, (2) magmatic Fe-Au deposits, (3) sedimentary polymetallic deposits, (4) polymetallic skarn deposits, and (5) palaeoplacers associated with karsts. The porphyry Cu-Au and polymetallic skarn deposits are associated with quartz-albite porphyry bodies. The Fe-Au and polymetallic sedimentary deposits are part of an ore-forming system that produced considerable Au in the Beiya area, and are characterised by low concentrations of La, Ti, and Co, and high concentrations of Y, Yb, and Sc. The Cenozoic porphyries in western Yunnan display increased alkalinity away from the Triassic Jinshajiang suture. Distribution of both the porphyries and sedimentary deposits in the Beiya area are interpreted to be related to partial melting in a disjointed region between upper mantle lithosphere of the Yangtze Plate and Gondwana continent, and lie within a shear zone between buried Palaeo-Tethyan oceanic lithosphere and upper mantle lithosphere, caused by the subduction and collision of India and Asia. ?? 2006 Elsevier B.V. All rights reserved.

  7. Geology and porphyry copper-type alteration-mineralization of igneous rocks at the Christmas Mine, Gila County, Arizona

    USGS Publications Warehouse

    Koski, Randolph A.

    1979-01-01

    The Christmas copper deposit, located in southern Gila County, Arizona, is part of the major porphyry copper province of southwestern North America. Although Christmas is known for skarn deposits in Paleozoic carbonate rocks, ore-grade porphyry-type copper mineralization also occurs in a composite granodioritic intrusive complex and adjacent mafic volcanic country rocks. This study considers the nature, distribution, and genesis of alteration-mineralization in the igneous rock environment at Christmas. At the southeast end of the Dripping Spring Mountains, the Pennsylvanian Naco Limestone is unconformably overlain by the Cretaceous Williamson Canyon Volcanics, a westward-thinning sequence of basaltic volcanic breccia and lava flows, and subordinate clastic sedimentary rocks. Paleozoic and Mesozoic strata are intruded by Laramide-age dikes, sills, and small stocks of hornblende andesite porphyry and hornblende rhyodacite porphyry, and the mineralized Christmas intrusive complex. Rocks of the elongate Christmas stock, intruded along an east-northeast-trending fracture zone, are grouped into early, veined quartz diorite (Dark Phase), biotite granodiorite porphyry (Light Phase), and granodiorite; and late, unveined dacite porphyry and granodiorite porphyry. Biotite rhyodacite porphyry dikes extending east and west from the vicinity of the stock are probably coeval with biotite granodiorite porphyry. Accumulated normal displacement of approximately 1 km along the northwest-trending Christmas-Joker fault system has juxtaposed contrasting levels (lower, intrusive-carbonate rock environment and upper, intrusive-volcanic rock environment) within the porphyry copper system. K-Ar age determinations and whole-rock chemical analyses of the major intrusive rock types indicate that Laramide calc-alkaline magmatism and ore deposition at Christmas evolved over an extended period from within the Late Cretaceous (~75-80 m.y. ago) to early Paleocene (~63-61 m.y. ago). The sequence of

  8. A tectonic model for the spatial occurrence of porphyry copper and polymetallic vein deposits - applications to Central Europe

    USGS Publications Warehouse

    Drew, Lawrence J.

    2006-01-01

    A structural-tectonic model, which was developed to assess the occurrence of undiscovered porphyry copper deposits and associated polymetallic vein systems for the Matra Mountains, Hungary, has been expanded here and applied to other parts of central Europe. The model explains how granitoid stocks are emplaced and hydrothermal fluids flow within local strain features (duplexes) within strike-slip fault systems that develop in continental crust above subducting plates. Areas of extension that lack shear at the corners and along the edges of the fault duplexes are structural traps for the granitoid stocks associated with porphyry copper deposits. By contrast, polymetallic vein deposits are emplaced where shear and extension are prevalent in the interior of the duplexes. This model was applied to the Late Cretaceous-age porphyry copper and polymetallic vein deposits in the Banat-Timok-Srednogorie region of Romania-Serbia-Bulgaria and the middle Miocene-age deposits in Romania and Slovakia. In the first area, porphyry copper deposits are most commonly located at the corners, and occasionally along the edges, of strike-slip fault duplexes, and the few polymetallic vein deposits identified are located at interior sites of the duplexes. In the second area, the model accounts for the preferred sites of porphyry copper and polymetallic vein deposits in the Apuseni Mountains (Romania) and central Slovakian volcanic field (Slovakia).

  9. Late Carboniferous porphyry copper mineralization at La Voluntad, Neuquén, Argentina: Constraints from Re-Os molybdenite dating

    NASA Astrophysics Data System (ADS)

    Garrido, Mirta; Barra, Fernando; Domínguez, Eduardo; Ruiz, Joaquin; Valencia, Victor A.

    2008-07-01

    The La Voluntad porphyry Cu-Mo deposit in Neuquén, Argentina, is one of several poorly known porphyry-type deposits of Paleozoic to Early Jurassic age in the central and southern Andes. Mineralization at La Voluntad is related to a tonalite porphyry from the Chachil Plutonic Complex that intruded metasedimentary units of the Piedra Santa Complex. Five new Re-Os molybdenite ages from four samples representing three different vein types (i.e., quartz-molybdenite, quartz-sericite-molybdenite and quartz-sericite-molybdenite ± chalcopyrite-pyrite) are identical within error and were formed between ~312 to ~316 Ma. Rhenium and Os concentrations range between 34 to 183 ppm and 112 to 599 ppb, respectively. The new Re-Os ages indicate that the main mineralization event at La Voluntad, associated to sericitic alteration, was emplaced during a time span of 1.7 ± 3.2 Ma and that the deposit is Carboniferous in age, not Permian as previously thought. La Voluntad is the oldest porphyry copper deposit so far recognized in the Andes and indicates the presence of an active magmatic arc, with associated porphyry style mineralization, at the proto-Pacific margin of Gondwana during the Early Pennsylvanian.

  10. Porphyry copper assessment of British Columbia and Yukon Territory, Canada: Chapter C in Global mineral resource assessment

    USGS Publications Warehouse

    Mihalasky, Mark J.; Bookstrom, Arthur A.; Frost, Thomas P.; Ludington, Steve

    2011-01-01

    Western Canada has been thoroughly explored for porphyry copper deposits. The total estimated copper contained in known deposits is about 66.8 Mt (based on 2010 data), as compared to a 49 Mt mean of estimated copper in undiscovered deposits and a 34 Mt median of estimated copper in undiscovered deposits. The copper contained in known porphyry copper deposits represents about 58 percent of the total of known and undiscovered porphyry copper deposits (based on mean values). About 86 percent of the increase in estimated copper resources between 1993 and 2009 resulted from the discovery of extensions to known deposits. Nevertheless, exploration for undiscovered deposits continues, especially in and around significant prospects and in parts of permissive tracts that are mostly hidden beneath younger volcanic, sedimentary, or vegetated surficial cover.

  11. Model of the porphyry copper and polymetallic vein family of deposits - Applications in Slovakia, Hungary, and Romania

    USGS Publications Warehouse

    Drew, L.J.

    2003-01-01

    A tectonic model useful in estimating the occurrence of undiscovered porphyry copper and polymetallic vein systems has been developed. This model is based on the manner in which magmatic and hydrothermal fluids flow and are trapped in fault systems as far-field stress is released in tectonic strain features above subducting plates (e.g. strike-slip fault systems). The structural traps include preferred locations for stock emplacement and tensional-shear fault meshes within the step-overs that localize porphyry- and vein-style deposits. The application of the model is illustrated for the porphyry copper and polymetallic vein deposits in the Central Slovakian Volcanic Field, Slovakia; the Ma??tra Mountains, Hungary; and the Apuseni Mountains, Romania.

  12. Digital data base application to porphyry copper mineralization in Alaska; case study summary

    USGS Publications Warehouse

    Trautwein, Charles M.; Greenlee, David D.; Orr, Donald G.

    1982-01-01

    The purpose of this report is to summarize the progress in use of digital image analysis techniques in developing a conceptual model for assessing porphyry copper mineral potential. The study area consists of approximately the southern one-half of the 1? by 3? Nabesna quadrangle in east-central Alaska. The digital geologic data base consists of data compiled under the Alaskan Mineral Resource Assessment Program (AMRAP) as well as digital elevation data and Landsat spectral reflectance data from the Multispectral Scanner System. The digital data base used to develop and implement a conceptual model for porphyry-type copper mineralization consisted of 16 original data types and 18 derived data sets formatted in a grid-cell (raster) structure and registered to a map base in the Universal Transverse Mercator (UTM) projection. Minimum curvature and inverse distance squared interpolation techniques were used to generate continuous surfaces from sets of irregularly spaced data points. Processing requirements included: (1) merging or overlaying of data sets, (2) display and color coding of maps and images, (3) univariate and multivariate statistical analyses, and (4) compound overlaying operations. Data sets were merged and processed to create stereoscopic displays of continuous surfaces. The ratio of several data sets were calculated to evaluate relative variations and to enhance the display of surface alteration (gossans). Factor analysis and principal components analysis techniques were used to determine complex relationships and correlations between data sets. The resultant model consists of 10 parameters that identify three areas most likely to contain porphyry copper mineralization; two of these areas are known occurrences of mineralization and the third is not well known. Field studies confirmed that the three areas identified by the model have significant copper potential.

  13. Mineral exploration potential of ERTS-1 data. [porphyry copper deposits in Arizona

    NASA Technical Reports Server (NTRS)

    Brewer, W. A. (Principal Investigator); Erskine, M. C., Jr.; Prindle, R. O.; Haenggi, W. T.

    1974-01-01

    The author has identified the following significant results. ERTS-1 imagery of an area approximately 15,000 square miles in Arizona was interpreted for regional structure and tectonic units. Eight fault systems were identified by trend, of which two, northeast and northwest, are considered to be related to porphyry copper mineralization. Nine tectonic units can be identified on the imagery as distinct geological identities. The boundaries between these units can be correlated with theoretical shear directions related to the San Andreas stress system. Fourier analysis of the N 50 W fault trend indicates a fundamental spacing between Fourier energy maxima that can be related to distances between copper deposits.

  14. Global mineral resource assessment: porphyry copper assessment of Mexico: Chapter A in Global mineral resource assessment

    USGS Publications Warehouse

    Hammarstrom, Jane M.; Robinson,, Gilpin R.; Ludington, Steve; Gray, Floyd; Drenth, Benjamin J.; Cendejas-Cruz, Francisco; Espinosa, Enrique; Pérez-Segura, Efrén; Valencia-Moreno, Martín; Rodríguez-Castañeda, José Luis; Vásquez-Mendoza, Rigobert; Zürcher, Lukas

    2010-01-01

    This report includes a brief overview of porphyry copper deposits in Mexico, a description of the assessment process used, a summary of results, and appendixes. Appendixes A through K contain summary information for each tract, as follows: location, the geologic feature assessed, the rationale for tract delineation, tables and descriptions of known deposits and significant prospects, exploration history, model selection, rationale for the estimates, assessment results, and references. The accompanying digital map files (shapefiles) provide permissive tract outlines, assessment results, and data for deposits and prospects in a GIS format (appendix L).

  15. Porphyry copper assessment of eastern Australia: Chapter L in Global mineral resource assessment

    USGS Publications Warehouse

    Bookstrom, Arthur A.; Len, Richard A.; Hammarstrom, Jane M.; Robinson,, Gilpin R.; Zientek, Michael L.; Drenth, Benjamin J.; Jaireth, Subhash; Cossette, Pamela M.; Wallis, John C.

    2014-01-01

    This assessment estimates that 15 undiscovered deposits contain an arithmetic mean of ~21 million metric tons or more of copper in four tracts, in addition to the 24 known porphyry copper deposits that contain identified resources of ~16 million metric tons of copper. In addition to copper, the mean expected amount of undiscovered byproduct gold predicted by the simulation is ~1,500 metric tons. The probability associated with these arithmetic means is on the order of 30 percent. Median expected amounts of metals predicted by the simulations may be ~50 percent lower than mean estimates.

  16. Porphyry copper deposits of the world: database, maps, and preliminary analysis

    USGS Publications Warehouse

    Singer, Donald A.; Berger, Vladimir I.; Moring, Barry C.

    2002-01-01

    Mineral deposit models are important in exploration planning and quantitative resource assessments for two reasons: (1) grades and tonnages among deposit types are significantly different, and (2) many types occur in different geologic settings that can be identified from geologic maps. Mineral deposit models are the keystone in combining the diverse geoscience information on geology, mineral occurrences, geophysics, and geochemistry used in resource assessments and mineral exploration. Far too few thoroughly explored mineral deposits are available in most local areas for reliable identification of the important geoscience variables or for robust estimation of undiscovered deposits—thus we need mineral-deposit models. Globally based deposit models, such as those presented here, allow recognition of important features because the global models demonstrate how common different features are. Well-designed and -constructed deposit models allow geologists to know from observed geologic environments the possible mineral deposit types that might exist, and allow economists to determine the possible economic viability of these resources in the region. Thus, mineral deposit models play the central role in transforming geoscience information to a form useful to policy makers. The foundation of mineral deposit models is information about known deposits—the purpose of this publication is to make this kind of information available in digital form for a group of porphyry copper deposits. This publication contains a computer file of information on porphyry copper deposits around the world. It also presents new grade and tonnage models for three subtypes of porphyry copper deposits, maps showing locations and general ages of these deposits, and a preliminary analysis with a number of figures summarizing many of the properties of these porphyry-style deposits. These summaries can be considered a new, quantified, form of most parts of descriptive models such as those in Cox and

  17. Inverse solution for crystal fractionation in a periodically tapped magma chamber, Sierrita porphyry copper deposit, Arizona

    SciTech Connect

    Anthony, E.Y.; Titley, S.R.

    1985-01-01

    Inversion techniques have been used to simultaneously solve for the initial concentrations, distribution coefficients, and degrees of crystallization for a suite of Laramide rocks related to subduction and porphyry copper mineralization. The suite includes diorite, andesite, and granodiorite. The granodiorite has differentiated in place to a granite core and it is this granite which immediately precedes mineralization. To perform the inversion one must verify that the rocks are genetically related by crystallization or melting. Their comagmatic nature is suggested by the similarity throughout the suite in the ratios of incompatible elements and in the few available isotopic determinations. The geochemical path of crystallization is indicated by the decrease in compatible elements and increase in incompatible elements. Inversion of the trace element data yields high initial concentrations for elements such as Ba and Ce and low concentrations for the transition metals, which is consistent with crustal melting. Thus, there was s substantial magma chamber at depth from which the more felsic liquids the authors sample have separated. The residence time of this chamber was not less than 6 million years. Such a prolonged history has been observed in other porphyry systems for which 10 million years of igneous activity and 2 million years of intermittent mineralization are recorded.

  18. Porphyry copper deposit formation by sub-volcanic sulphur dioxide flux and chemisorption

    NASA Astrophysics Data System (ADS)

    Henley, Richard W.; King, Penelope L.; Wykes, Jeremy L.; Renggli, Christian J.; Brink, Frank J.; Clark, David A.; Troitzsch, Ulrike

    2015-03-01

    Porphyry copper deposits--the primary source of the world’s copper--are a consequence of the degassing of intrusion complexes in magmatic arcs associated with ancient subduction zones. They are characterized by copper and iron sulphides, commonly found with anhydrite (CaSO4), over scales of several kilometres through intensely altered and fractured rocks. The magmatic source of the metals is broadly understood, but the processes that transport and deposit the metals at the megaton scale are unclear. The hydrogen sulphide necessary for metal deposition is commonly assumed to form by a reaction between sulphur dioxide and water, but this reaction is inefficient and cannot explain the formation of economic-grade deposits. Here we use high-temperature laboratory experiments to show that a very rapid chemisorption reaction occurs between sulphur dioxide gas, a principal component of magmatic gas mixtures, and calcic feldspar, an abundant mineral in the arc crust. The chemisorption reaction generates the mineral anhydrite and hydrogen sulphide gas, and triggers deposition of metal sulphides. We use thermodynamic calculations to show that as magmatic gas cools and expands the concentration of hydrogen sulphide gas increases exponentially to drive efficient deposition of metal sulphides and consequent formation of economic-grade porphyry copper deposits.

  19. Combining ZTEM and Magnetotelluric Data to Enhance Three-dimensional Conductivity Models of Porphyry Copper Deposits

    NASA Astrophysics Data System (ADS)

    Lee, B.; Huebert, J.; Abbassi, B.; Liu, L.; Unsworth, M. J.; Richards, J. P.; Cheng, L.; Oldenburg, D.

    2013-12-01

    The airborne Z-Axis Tipper Electromagnetic (ZTEM) method uses natural low frequency electromagnetic signals to determine subsurface electrical conductivity from the surface to a depth of 2 km. It measures the ratio of vertical magnetic field to the horizontal magnetic field with signals in the frequency range 30 -720 Hz. ZTEM is highly effective at determining lateral changes in subsurface conductivity, but does not give the same vertical resolution as the ground-based magnetotelluric (MT) method that measures the ratio of electric to magnetic fields. However, MT surveys require ground contact to measure electric fields and as a consequence are slower to deploy and provide a coarser sampling of conductive features. Since both methods derive the tipper from measured vertical and horizontal magnetic fields, these techniques can be used in a joint approach to create electrical conductivity models. Synthetic MT inversions show that the technique is sensitive to the vertical depth of conductors, complementing the lateral sensitivity of ZTEM. A key application of ZTEM is that metallic sulfide-bearing ore bodies can be resolved because of their high electrical conductivity relative to the host rock. Porphyry copper deposits contain a less distinct geophysical response though, and require additional geologic information. Here we present conductivity models from the Morrison porphyry copper deposit in British Columbia, Canada where the implementation of MT data provides background conductivity and vertical constraints for the three-dimensional ZTEM models.

  20. The formation of Qulong adakites and their relationship with porphyry copper deposit: Geochemical constraints

    NASA Astrophysics Data System (ADS)

    Hu, Yong-bin; Liu, Ji-qiang; Ling, Ming-xing; Ding, Wei; Liu, Yan; Zartman, Robert E.; Ma, Xiu-feng; Liu, Dun-yi; Zhang, Chan-chan; Sun, Sai-jun; Zhang, Li-peng; Wu, Kai; Sun, Wei-dong

    2015-04-01

    Qulong porphyry Cu deposit is the largest Cu deposit in China so far discovered, with total reserves of 10.6 Mt Cu@0.5% and 0.5 Mt Mo@0.03%. The petrogenesis of the Miocene intrusion and its genetic association with Cu mineralization have been debated. This study presents new results on whole rock major and trace elements, Sr-Nd isotopes, zircon U-Pb dating, Hf-O isotopic compositions of the Qulong ore-bearing and barren adakites. All the Qulong adakites studied here have low MgO (< 2 wt.%), high K2O (between 2 wt.% and 6 wt.%), with K2O/Na2O ratios ranging from 0.2-2.0. The SiO2 contents are mostly higher than 64 wt.%. These are dramatically different from ore-forming adakites in the circum-Pacific region and other places in general. Ore-bearing adakites have systematically higher SiO2 and K2O compared with barren ones, likely due to the addition of Si and K during alteration and mineralization. Magmatic zircons from these two series of intrusions have U-Pb ages of 16.6 ± 0.5-17.0 ± 0.6 Ma and 16.7 ± 0.3-17.4 ± 0.4 Ma, respectively, which are identical to each other within analytical errors but are systematically older than although marginally overlap with the Re-Os isochron ages of 15.36 ± 0.21-16.41 ± 0.48 Ma. The Qulong porphyries have geochemical characteristics of typical adakites, with Sr = 259-1195 ppm, Y = 1.91-9.12 ppm, Yb = 0.2-0.92 ppm, Sr/Y = 49-202 ppm, and (La/Yb)n = 13-49 for both ore-bearing and barren adakites. In a Sr/Y versus (La/Yb)n diagram, most of the samples plot in the low part of circum-Pacific field, close to the field defined by Dabie adakites. Some of the ore-bearing adakites even plot in the Dabie adakite field, indicating that both slab melts and lower continental crust melts have been involved. Zircons from the ore-bearing adakites have δ18O ranging from 5.1 to 7.3‰ (average 6.4‰) and εHf(t) from 1.9 to 10.4‰, which plot close to MORB. Similarly, zircons from the barren adakite have δ18O ranging from 4.0 to 7.4

  1. Geochronology and geochemistry of the Badaguan porphyry Cu-Mo deposit in Derbugan metallogenic belt of the NE China, and their geological significances

    NASA Astrophysics Data System (ADS)

    Gao, Bingyu; Zhang, Lianchang; Jin, Xindi; Li, Wenjun; Chen, Zhiguang; Zhu, Mingtian

    2016-03-01

    The Badaguan porphyry Cu-Mo deposit belongs to the Derbugan metallogenic belt, which is located in the Ergun block, NE China. In the mining area, the Cu-Mo mineralization mainly occurs in quartz diorite porphyry and is hosted within silicified-sericitized and sericite alteration zone. Geochemical results of the host porphyry is characterized by high SiO2, high Al2O3, low MgO, weak positive Eu anomalies and clearly HREE depletion, high Sr, low Y and low Yb, similar to those of adakite. The Sr-Nd isotopic composition of the host porphyry displays an initial (87Sr/86Sr)i ratio of 0.7036-0.7055 and positive Nd( t) values of +0.1 to +0.6, which are similar to the OIB, reflecting the source of the host porphyry may derive from subducted ocean slab, and the new lower crust also had some contribution to the magma sources. The SIMS zircon U-Pb age from the host porphyry is 229 ± 2 Ma. The Re-Os isochron age for the molybdenite in the deposit is 225 ± 2 Ma closed to zircon U-Pb age of the host porphyry, indicating that Cu-Mo mineralization event occurred in Triassic. Combining the geology-geochemistry of the host porphyry and the regional tectonic evolution, we infer that the subduction processes of Mongol-Okhotsk oceanic slab under the Ergun block led to the formation of the Badaguan porphyry Cu-Mo deposit during the Triassic.

  2. Geologic and environmental characteristics of porphyry copper deposits with emphasis on potential future development in the Bristol Bay Watershed, Alaska

    USGS Publications Warehouse

    Seal, Robert R., II

    2012-01-01

    Pebble; Big Chunk is approximately 30 miles (48 km) north-northwest of Pebble; and Shotgun is approximately 110 miles (177 km) northwest of Pebble. The H and D Block prospects, west of Pebble, represent additional porphyry copper exploration targets in the watershed.

  3. Iron concretions within a highly altered unit of the Berlins Porphyry, New Zealand: an abiotic or biotic story?

    NASA Astrophysics Data System (ADS)

    Cox, Toni L.; Oze, Christopher; Horton, Travis W.

    2016-09-01

    The Berlins Porphyry located on the South Island of New Zealand provides an opportunity to examine iron concretions formed in a subterranean system. Specifically, an alteration zone within the Berlins Porphyry contains iron concretions similar to sedimentary biologically-mediated iron concretions. Here, we provide evidence for two sources of dissolved Fe (II) that potentially aided in the formation of the iron concretions. Furthermore, we discuss the potential for microbial involvement in the anaerobic oxidation of Fe (II) to Fe (III) to form magnetite. Evidence in support of this hypothesis includes the low concentrations of iron and sulfur in the white hydrothermally altered porphyry outcrop and concretion cores; concentrated pyrite and magnetite mineralisation surrounding the cores; and δ13C values indicative of organic carbon (averaging -26 ‰ ± 4 ‰) within the iron cement, porphyry-core-boundary and outer weathered rinds of the concretions. Overall, these unusually preserved iron concretions could represent a new environmental niche for microorganisms and a potential analogue for microbially induced iron-oxidation. More importantly, this study illustrates the many obstacles involved in analysing and interpreting potential subterranean biosignatures.

  4. Porphyry copper assessment of Europe, exclusive of the Fennoscandian Shield: Chapter K in Global mineral resource assessment

    USGS Publications Warehouse

    Sutphin, David M.; Hammarstrom, Jane M.; Drew, Lawrence J.; Large, Duncan E.; Berger, Byron R.; Dicken, Connie L.; DeMarr, Michael W.; with contributions from Billa, Mario; Briskey, Joseph A.; Cassard, Daniel; Lips, Andor; Pertold, Zdeněk; Roşu, Emilian

    2013-01-01

    The assessment includes an overview with summary tables. Detailed descriptions of each tract, including the rationales for delineation and assessment, are given in appendixes A–G. Appendix H describes a geographic information system (GIS) that includes tract boundaries and point locations of known porphyry copper deposits and significant prospects.

  5. A Long-Lived Porphyry Ore Deposit and Associated Upper Crustal Silicic Magma Body, Bajo de la Alumbrera, Argentina

    NASA Astrophysics Data System (ADS)

    Harris, A. C.; Allen, C. M.; Reiners, P. W.; Dunlap, W. J.; Cooke, D. R.; Campbell, I. H.; White, N. C.

    2004-05-01

    Porphyry Cu deposits form within and adjacent to small porphyritic intrusions that are apophyses to larger silicic magma bodies that reside in the upper parts of the Earth's crusts. Centred on these intrusions are hydrothermal systems of exsolved magmatic fluid with a carapace of convectively circulating meteoric water. We have applied several different dating techniques to assess the longevity of the magmatic-hydrothermal system and to define the cooling history of porphyry intrusions at the Bajo de la Alumbrera porphyry Cu-Au deposit, Argentina. The closure temperatures of these techniques range from 800oC (zircon U-Pb) to ~70oC (apatite (U-Th)/He; Fig. 1). The resulting cooling history indicates that the magmatic-hydrothermal system cooled to ca. 200oC by ~1.5 m.y. after the last porphyry intrusion (i.e., 6.96±0.09 Ma; U-Pb zircon age). Based on (U-Th)/He apatite data (closure temperature ~60-70oC), exposure and cessation of the system occurred before 4 Ma. The longevity of the magmatic-hydrothermal system indicated by these results is inconsistent with accepted mechanisms for porphyry Cu deposit formation. Depending on wallrock permeability, depth and cooling method, a 2 km wide by 3 km high intrusion has been predicted to cool between 0.01 to 0.1 m.y. (marked as the grey interval; Cathles et al., 1997 Economic Geology). We have obtained numerous age determinations younger than the U-Pb zircon age of the last known intrusion at Bajo de la Alumbrera. These imply that simple cooling of the small, mineralized porphyries did not happen. For the magmatic-hydrothermal system to have been sustained for longer than 0.1 m.y., either 1) younger small intrusions have been episodically emplaced below the youngest known intrusions, thus prolonging heat flow, or 2) fluids derived from a deeper and larger parental intrusion have been episodically discharged through the ore deposit long after the porphyry intrusion had lost its available heat. In either case, the longevity of

  6. The optimisation of electrokinetic remediation for heavy metals and radioactivity contamination on Holyrood-Lunas soil (acrisol species) in Sri Gading Industrial Area, Batu Pahat, Johor, Malaysia.

    PubMed

    Mohamed Johar, S; Embong, Z

    2015-11-01

    The optimisation of electrokinetic remediation of an alluvial soil, locally named as Holyrood-Lunas from Sri Gading Industrial Area, Batu Pahat, Johor, Malaysia, had been conducted in this research. This particular soil was chosen due to its relatively high level of background radiation in a range between 139.2 and 539.4 nGy h(-1). As the background radiation is correlated to the amount of parent nuclides, (238)U and (232)Th, hence, a remediation technique, such as electrokinetic, is very useful in reducing these particular concentrations of heavy metal and radionuclides in soils. Several series of electrokinetics experiments were performed in laboratory scale in order to study the influence of certain electrokinetic parameters in soil. The concentration before (pre-electrokinetic) and after the experiment (post-electrokinetic) was determined via X-ray fluorescence (XRF) analysis technique. The best electrokinetic parameter that contributed to the highest achievable concentration removal of heavy metals and radionuclides on each experimental series was incorporated into a final electrokinetic experiment. Here, High Pure Germanium (HPGe) was used for radioactivity elemental analysis. The XRF results suggested that the most optimised electrokinetic parameters for Cr, Ni, Zn, As, Pb, Th and U were 3.0 h, 90 volts, 22.0 cm, plate-shaped electrode by 8 × 8 cm and in 1-D configuration order whereas the selected optimised electrokinetic parameters gave very low reduction of (238)U and (232)Th at 0.23 ± 2.64 and 2.74 ± 23.78 ppm, respectively.

  7. Potential links between porphyry copper deposits and exhumed metamorphic basement complexes in northern Chile

    NASA Astrophysics Data System (ADS)

    Cooper, Frances; Docherty, Alistair; Perkins, Rebecca

    2014-05-01

    Porphyry copper deposits (PCDs) are typically associated with magmatic arcs in compressional subduction zone settings where thickened crust and fractionated calc-alkaline magmas produce favourable conditions for copper mineralisation. A classic example is the Eocene-Oligocene PCD belt of Chile, the world's leading copper producing country. In other parts of the world, older late Cretaceous to early Tertiary PCDs are found in regions of former subduction-related magmatism that have undergone subsequent post-orogenic crustal extension, such as the Basin and Range province of western North America, and the Eurasian Balkan-Carpathian-Dinaride belt. In the Basin and Range there is a striking correlation between the location of many PCDs and exhumed metamorphic core complexes (isolated remnants of the middle to lower crust exhumed during extensional normal faulting). This close spatial relationship raises questions about the links between the two. For example, are their exhumation histories related? Could the presence of impermeable metamorphic rocks at depth affect and localise mineralising fluids? In Chile there appears to be a similar spatial relationship between PCDs and isolated outcrops of exhumed metamorphic basement. In northern Chile, isolated exposures of high-grade metamorphic gneisses and amphibolites are thought to be exhumed remnants of the pre-subduction Proterozoic-Paleozoic continental margin of Gondwana [2], although little is known about when they were exhumed and by what mechanism. For example, the Limón Verde metamorphic complex, exhumed from a depth of ca. 50 km, is situated adjacent to Chuquicamata, the largest open pit copper mine in the world. In northernmost Chile, another metamorphic exposure, the Belén complex, sits close to the Dos Hermanos PCD, a small deposit that is not actively mined. Comprising garnet-bearing gneisses and amphibolites, the Belén is thought to have been exhumed from a depth of ca. 25 km, but when and how is unclear [3

  8. Porphyry Copper Deposits of the World: Database and Grade and Tonnage Models, 2008

    USGS Publications Warehouse

    Singer, Donald A.; Berger, Vladimir I.; Moring, Barry C.

    2008-01-01

    This report is an update of earlier publications about porphyry copper deposits (Singer, Berger, and Moring, 2002; Singer, D.A., Berger, V.I., and Moring, B.C., 2005). The update was necessary because of new information about substantial increases in resources in some deposits and because we revised locations of some deposits so that they are consistent with images in GoogleEarth. In this report we have added new porphyry copper deposits and removed a few incorrectly classed deposits. In addition, some errors have been corrected and a number of deposits have had some information, such as grades, tonnages, locations, or ages revised. Colleagues have helped identify places where improvements were needed. Mineral deposit models are important in exploration planning and quantitative resource assessments for a number of reasons including: (1) grades and tonnages among deposit types are significantly different, and (2) many types occur in different geologic settings that can be identified from geologic maps. Mineral deposit models are the keystone in combining the diverse geoscience information on geology, mineral occurrences, geophysics, and geochemistry used in resource assessments and mineral exploration. Too few thoroughly explored mineral deposits are available in most local areas for reliable identification of the important geoscience variables or for robust estimation of undiscovered deposits?thus we need mineral-deposit models. Globally based deposit models allow recognition of important features because the global models demonstrate how common different features are. Well-designed and -constructed deposit models allow geologists to know from observed geologic environments the possible mineral deposit types that might exist, and allow economists to determine the possible economic viability of these resources in the region. Thus, mineral deposit models play the central role in transforming geoscience information to a form useful to policy makers. The foundation of

  9. Sulfide mineral paragenesis at the Hugo Dummett porphyry Cu-Au deposit, Oyu Tolgoi, South Mongolia

    NASA Astrophysics Data System (ADS)

    Sanjaa, M.; Fujimaki, H.

    2008-12-01

    Mineralogical studies of ore minerals have been conducted for the Hugo Dummett porphyry copper deposit. The Hugo Dummett porphyry copper gold deposit is located in the South Gobi region, Mongolia and currently being explored. This deposit divided into the Cu-rich South Hugo Dummett and the Cu-Au-rich North Hugo Dummett deposits. The Hugo Dummett deposits contain 1.08% copper (1.16 billion tonnes in total) and 0.23 g/t gold. Copper-gold mineralizations at this deposit are centered on a high-grade copper (typically > 2.5%) and gold (0.5-2 g/t) zone of intense quartz stockwork veining. The high grade copper and gold zone is mainly within the Late Devonian quartz monzodiorite intrusions and augite basalt, also locally occurs in dacitic rocks. Intense quartz veining forms a lens up to 100 m wide hosted by augite basalt and partly by quartz monzodiorite. Although many explorations have been carried out, but only a few scientific works were done in the Oyu Tolgoi mining area. Therefore the nature of copper-gold mineralization and orgin of the deposit is not fully understood. North Hugo Dummett and South Hugo Dummett porphyry copper-gold deposits are characterized by three mineralized stages based on our study: (1) early stage (2) middle stage and (3) late stage. The main copper- gold mineralization occurs in the early and middle stages, which is related to the quartz monzodiorite and dacitic rocks. Pyrite, chalcopyrite and bornite were continuously crystallized from early to late stage. The early stage of pyrite, chalcopyrite, bornite, molybdenite and sphalerite were replaced by middle stage of minerals. The middle stage minerals are sphalerite, tennantite, tetrahedrite, chalcocite, covellite, eugenite, galena, electrum, and gold, those are dominantly occur in the quartz monzodiorite. Additional pyrite, bornite and chalcopyrite were also deposited during this stage. In the late stage, pyrite, chalcopyrite and bornite are dominantly occurs as veins, veinlets and fracture

  10. Geochronology, geochemistry, and tectonic environment of porphyry mineralization in the central Alaska Peninsula

    USGS Publications Warehouse

    Wilson, Frederic H.; Cox, Dennis P.

    1983-01-01

    Porphyry type sulfide systems on the central Alaska Peninsula occupy a transition zone between the Aleutian island magmatic arc and the continental magmatic arc of southern Alaska. Mineralization occurs associated with early and late Tertiary magmatic centers emplaced through a thick section of Mesozoic continental margin clastic sedimentary rocks. The systems are of the molybdenum-rich as opposed to gold-rich type and have anomalous tungsten, bismuth, and tin, attributes of continental-margin deposits, yet gravity data suggest that at least part of the study area is underlain by oceanic or transitional crust. Potassium-argon age determinations indicate a variable time span of up to 2 million years between emplacement and mineralization in a sulfide system with mineralization usually followed by postmineral intrusive events. Finally, mineralization in the study area occurred at many times during the time span of igneous activity and should be an expected stage in the history of a subduction related magmatic center.

  11. Column bioleaching of uranium embedded in granite porphyry by a mesophilic acidophilic consortium.

    PubMed

    Qiu, Guanzhou; Li, Qian; Yu, Runlan; Sun, Zhanxue; Liu, Yajie; Chen, Miao; Yin, Huaqun; Zhang, Yage; Liang, Yili; Xu, Lingling; Sun, Limin; Liu, Xueduan

    2011-04-01

    A mesophilic acidophilic consortium was enriched from acid mine drainage samples collected from several uranium mines in China. The performance of the consortium in column bioleaching of low-grade uranium embedded in granite porphyry was investigated. The influences of several chemical parameters on uranium extraction in column reactor were also investigated. A uranium recovery of 96.82% was achieved in 97 days column leaching process including 33 days acid pre-leaching stage and 64 days bioleaching stage. It was reflected that indirect leaching mechanism took precedence over direct. Furthermore, the bacterial community structure was analyzed by using Amplified Ribosomal DNA Restriction Analysis. The results showed that microorganisms on the residual surface were more diverse than that in the solution. Acidithiobacillus ferrooxidans was the dominant species in the solution and Leptospirillum ferriphilum on the residual surface.

  12. Porphyry copper deposit model: Chapter B in Mineral deposit models for resource assessment

    USGS Publications Warehouse

    Ayuso, Robert A.; Barton, Mark D.; Blakely, Richard J.; Bodnar, Robert J.; Dilles, John H.; Gray, Floyd; Graybeal, Fred T.; Mars, John L.; McPhee, Darcy K.; Seal, Robert R., II; Taylor, Ryan D.; Vikre, Peter G.; John, David A.

    2010-01-01

    This report contains a revised descriptive model of porphyry copper deposits (PCDs), the world's largest source (about 60 percent) and resource (about 65 percent) of copper and a major source of molybdenum, gold and silver. Despite relatively low grades (average 0.44 percent copper in 2008), PCDs have significant economic and societal impacts due to their large size (commonly hundreds of millions to billions of metric tons), long mine lives (decades), and high production rates (billions of kilograms of copper per year). The revised model describes the geotectonic setting of PCDs, and provides extensive regional- to deposit-scale descriptions and illustrations of geological, geochemical, geophysical, and geoenvironmental characteristics. Current genetic theories are reviewed and evaluated, knowledge gaps are identified, and a variety of exploration and assessment guides are presented. A summary is included for users seeking overviews of specific topics.

  13. An orientation soil survey at the Pebble Cu-Au-Mo porphyry deposit, Alaska

    USGS Publications Warehouse

    Smith, Steven M.; Eppinger, Robert G.; Fey, David L.; Kelley, Karen D.; Giles, S.A.

    2009-01-01

    Soil samples were collected in 2007 and 2008 along three traverses across the giant Pebble Cu-Au-Mo porphyry deposit. Within each soil pit, four subsamples were collected following recommended protocols for each of ten commonly-used and proprietary leach/digestion techniques. The significance of geochemical patterns generated by these techniques was classified by visual inspection of plots showing individual element concentration by each analytical method along the 2007 traverse. A simple matrix by element versus method, populated with a value based on the significance classification, provides a method for ranking the utility of methods and elements at this deposit. The interpretation of a complex multi-element dataset derived from multiple analytical techniques is challenging. An example of vanadium results from a single leach technique is used to illustrate the several possible interpretations of the data.

  14. Porphyry-copper ore shells form at stable pressure-temperature fronts within dynamic fluid plumes.

    PubMed

    Weis, P; Driesner, T; Heinrich, C A

    2012-12-21

    Porphyry-type ore deposits are major resources of copper and gold, precipitated from fluids expelled by crustal magma chambers. The metals are typically concentrated in confined ore shells within vertically extensive vein networks, formed through hydraulic fracturing of rock by ascending fluids. Numerical modeling shows that dynamic permeability responses to magmatic fluid expulsion can stabilize a front of metal precipitation at the boundary between lithostatically pressured up-flow of hot magmatic fluids and hydrostatically pressured convection of cooler meteoric fluids. The balance between focused heat advection and lateral cooling controls the most important economic characteristics, including size, shape, and ore grade. This self-sustaining process may extend to epithermal gold deposits, venting at active volcanoes, and regions with the potential for geothermal energy production.

  15. Lead isotope signatures of epithermal and porphyry-type ore deposits from the Romanian Carpathian Mountains

    NASA Astrophysics Data System (ADS)

    Marcoux, Eric; Grancea, Luminita; Lupulescu, Marian; Milési, Jean

    2002-03-01

    Lead isotope analyses have been performed on the two major Miocene mining districts of Romania, Baia Mare and Apuseni Mountains. These two districts have different non-overlapping 206Pb/204Pb isotopic signatures ranging from 18.752 to 18.876 and 18.497 to 18.740. In the Baia Mare district, epithermal deposits are overall homogeneous in their lead isotopic compositions and have values similar to the average of the calc-alkaline volcanic rocks. These results suggest a magmatic signature for the Pb (and possibly other metals) in the hydrothermal fluids. However, magmas in this district show isotopic evidence of crustal assimilation. In the southern Apuseni Mountains, the lead isotope compositions of sulfide minerals in porphyry copper deposits are clustered, confirming that Pb, and probably other metals, were derived principally from associated porphyry stocks. On the other hand, lead isotope data on sulfides in epithermal ore deposits are much more scattered, indicating a notable contribution of Pb from local country rocks. In the Apuseni Mountains, 'fertile' volcanics are few and appear to come from a more primitive mantle-derived source. Most of the analysed volcanic rocks seem 'barren'. Differences in lead isotopic compositions between the Baia Mare district and the Apuseni Mountains are due to a different basement, and probably to variations in crustal assimilation superimposed on variations in the mantle source composition. In the Apuseni Mountains, Pb may be partly inherited from the previous Mesozoic magmatic-hydrothermal stage. From a geodynamic point of view, it seems that the nature and the source of volcanic rocks and their position related to the collision area of the Carpathian arc are not the only factors controlling the 'fertility' of a volcanic district.

  16. Porphyry copper assessment of the Tethys region of western and southern Asia: Chapter V in Global mineral resource assessment

    USGS Publications Warehouse

    Zürcher, Lukas; Bookstrom, Arthur A.; Hammarstrom, Jane M.; Mars, John C.; Ludington, Stephen; Zientek, Michael L.; Dunlap, Pamela; Wallis, John C.; Drew, Lawrence J.; Sutphin, David M.; Berger, Byron R.; Herrington, Richard J.; Billa, Mario; Kuşcu, Ilkay; Moon, Charles J.; Richards, Jeremy P.; Zientek, Michael L.; Hammarstrom, Jane M.; Johnson, Kathleen M.

    2015-11-18

    The assessment estimates that the Tethys region contains 47 undiscovered deposits within 1 kilometer of the surface. Probabilistic estimates of numbers of undiscovered deposits were combined with grade and tonnage models in a Monte Carlo simulation to estimate probable amounts of contained metal. The 47 undiscovered deposits are estimated to contain a mean of 180 million metric tons (Mt) of copper distributed among the 18 tracts for which probabilistic estimates were made, in addition to the 62 Mt of copper already identified in the 42 known porphyry deposits in the study area. Results of Monte Carlo simulations show that 80 percent of the estimated undiscovered porphyry copper resources in the Tethys region are located in four tracts or sub-tracts.

  17. Porphyry copper assessment of Central America and the Caribbean Basin: Chapter I in Global mineral resource assessment

    USGS Publications Warehouse

    Gray, Floyd; Hammarstrom, Jane M.; Ludington, Stephen; Zürcher, Lukas; Nelson, Carl E.; Robinson,, Gilpin R.; Miller, Robert J.; Moring, Barry C.

    2014-01-01

    This assessment estimated a total mean of 37 undiscovered porphyry copper deposits within the assessed permissive tracts in Central America and the Caribbean Basin. This represents more than five times the seven known deposits. Predicted mean (arithmetic) resources that could be associated with these undiscovered deposits are about 130 million metric tons of copper and about 5,200 metric tons of gold, as well as byproduct molybdenum and silver. The reported identified resources for the seven known deposits total about 39 million metric tons of copper and about 930 metric tons of gold. The assessment area is estimated to contain nearly four times as much copper and six times as much gold in undiscovered porphyry copper deposits as has been identified to date.

  18. Geological and geochemical studies of the Shujiadian porphyry Cu deposit, Anhui Province, Eastern China: Implications for ore genesis

    NASA Astrophysics Data System (ADS)

    Wang, Shiwei; Zhou, Taofa; Yuan, Feng; Fan, Yu; White, Noel C.; Lin, Fengjie

    2015-05-01

    Most porphyry deposits in the world occur in magmatic arc settings and are related to subduction of oceanic plates. A small proportion of porphyry deposits occur in intracontinental settings, however they are still poorly understood. Shujiadian, a newly-discovered porphyry Cu deposit, is located in the Middle-Lower Yangtze River Valley metallogenic belt and belongs to the intracontinental class. The deposit has classic alteration zones defined by a core of potassic alteration and local Ca-silicate alteration, which is overprinted by a feldspar-destructive alteration zone and cut by veins containing epidote and chlorite. Wallrocks of the deposit are unreactive quartz-rich sedimentary rocks. Three main paragenetic stages have been recognized based on petrographic observations; silicate stage, quartz-sulfide stage, and sulfide-carbonate stage. Quartz + pyrite + chalcopyrite ± molybdenite veins, and quartz + chalcopyrite + pyrite veins of the quartz-sulfide stage contribute most of the copper, and chalcopyrite + chlorite ± pyrite ± pyrrhotite ± quartz ± illite veins of the sulfide-carbonate stage also contribute part of the copper; all the mineralized veins are associated with feldspar-destructive alteration. Investigations on the fluid inclusions in Shujiadian indicate that the ore-forming fluids had four evolutionary episodes: immiscibility and overpressure in the silicate stage, boiling in the quartz-sulfide stage and mixing with meteoric water in the sulfide-carbonate stage. Sulfur and strontium isotope studies suggest that ore metals were mainly derived from magmatic-hydrothermal fluids, and combined with our study of fluid inclusions, we infer that decompression, changes in oxygen fugacity and sulfur content were the main factors that caused Cu precipitation. Compared with porphyry deposits in magmatic arc settings, there are some differences in the ore-bearing rock, alteration, and the composition of ore-forming fluids.

  19. Re-Os and U-Pb geochronology of the Laochang Pb-Zn-Ag and concealed porphyry Mo mineralization along the Changning-Menglian suture, SW China: implications for ore genesis and porphyry Cu-Mo exploration

    NASA Astrophysics Data System (ADS)

    Deng, Xiao-Dong; Li, Jian-Wei; Zhao, Xin-Fu; Wang, Hong-Qiang; Qi, Liang

    2016-02-01

    Numerous polymetallic volcanogenic massive sulfide (VMS), vein, and replacement deposits are distributed along the Changning-Menglian suture zone in Sanjiang Tethyan metallogenic province, SW China. Laochang is the largest Pb-Zn-Ag vein and replacement deposit in this area, with a proven reserve of 0.51 Mt Pb, 0.34 Mt Zn, and 1,737 t Ag. Its age and relationship to magmatic events and VMS deposits in the region, however, have long been debated. In this paper, we present pyrite Re-Os and titanite U-Pb ages aiming to provide significant insights into the timing and genesis of the Pb-Zn-Ag mineralization. Pyrite grains in textural equilibrium with galena, sphalerite, and chalcopyrite from stratabound Pb-Zn-Ag and Cu-bearing Pb-Zn-Ag orebodies have a Re-Os isochron age of 45.7 ± 3.1 Ma (2 σ, mean square weighted deviation (MSWD) = 0.45), whereas titanite grains intergrown with sulfide minerals yield a weighted mean 206Pb/238U age of 43.4 ± 1.2 Ma (2 σ, n = 8). A Mo-mineralized granitic porphyry intersected by recent drilling below the Laochang Pb-Zn-Ag ores yields a zircon U-Pb age of 44.4 ± 0.4 Ma (2 σ, n = 12). Within analytical uncertainties, the ages of the Pb-Zn-Ag deposit and the concealed Mo-mineralized porphyry are indistinguishable, indicating that they are products of a single magmatic hydrothermal system. The results show that Laochang Pb-Zn-Ag deposit is significantly younger than the host mafic volcanic rock (zircon U-Pb age of 320.8 ± 2.7 Ma; 2 σ, n = 12) and Silurian VMS deposits along the Changning-Menglian suture zone, arguing against its origin as a Carboniferous VMS deposit as many researchers claimed. The initial 187Os/188Os ratio (0.540 ± 0.012) obtained from the pyrite Re-Os isochron suggests that metals were likely derived from the granitic porphyry that formed from a hybrid magma due to mixing of crustal- and mantle-derived melts, rather than from the mafic volcanic host rocks as previously thought. Our results favor that the Laochang

  20. Geochemistry and fluid characteristics of the Dalli porphyry Cu-Au deposit, Central Iran

    NASA Astrophysics Data System (ADS)

    Zarasvandi, Alireza; Rezaei, Mohsen; Raith, Johann; Lentz, David; Azimzadeh, Amir-Mortaza; Pourkaseb, Hooshang

    2015-11-01

    The Miocene Dalli porphyry Cu-Au deposit in the central part of Urumieh-Dokhtar magmatic arc is the first reported Au-rich porphyry Cu deposit in the Zagros orogenic belt. The Cu-Au mineralization is mainly hosted in diorite and quartz diorite intrusions, presenting as numerous veinlets in the altered wall rocks, with potassic, phyllic, and propylitic alteration developed. Based on the mineral assemblages and crosscutting relations of veinlets, hydrothermal mineralization-alteration occurred in at least three stages, characterized by veinlets of (1) Qtz + Kfs + Mag ± Ccp, (2) Qtz + Py + Ccp ± Bn ± Cv ± Cc and, (3) Qtz + Chl + Bt. The ore-bearing intrusions exhibit typical geochemical characteristics of subduction zone magmas, including LREE fractionated pattern, strong enrichment in LILE (Cs, Rb, Ba, Pb, and U), and depletion of HFSE, with marked negative Ti and Nb anomalies. The adakite-like ore-hosting porphyry intrusions are characterized by a systematic gradual decreasing and increasing of Y and Eu/Eu∗ with increasing SiO2 content, respectively. Moreover, they exhibit a significant increasing trend of Sr/Y with decreasing of Y, which indicates progressive hornblende fractionation and suppression of plagioclase fractionation during the evolution toward high water content of parental magma. A relatively flat HREE pattern with low Dyn/Ybn and Nb/Ta values may represent that amphibole played a more important role than garnet in the generation of the adakitic melts in the thickened lower crust. Based on the phase assemblages confirmed by detailed laser Raman spectroscopy analyses and proportion of solid, liquid, and gaseous components, five types of fluid inclusions were recognized, which are categorized as; (1) liquid-rich two phase (liquidH2O + vaporH2O) (IIA), (2) vapor-rich two phase (vaporH2O/CO2 + liquidH2O) (IIB), (3) high saline simple fluids (IIIA; liquidH2O + vaporH2O + Hl), (4) high saline opaque mineral-bearing fluids (IIIB; liquidH2O + vaporH2O

  1. Temporal Evolution of Volcanic and Plutonic Magmas Related to Porphyry Copper Ores Based on Zircon Geochemistry

    NASA Astrophysics Data System (ADS)

    Dilles, J. H.; Lee, R. G.; Wooden, J. L.; Koleszar, A. M.

    2015-12-01

    Porphyry Cu (Mo-Au) and epithermal Au-Ag ores are globally associated with shallow hydrous, strongly oxidized, and sulfur-rich arc intrusions. In many localities, long-lived magmatism includes evolution from early andesitic volcanic (v) and plutonic (p) rocks to later dacitic or rhyolitic compositions dominated by plutons. We compare zircon compositions from three igneous suites with different time spans: Yerington, USA (1 m.y., p>v), El Salvador, Chile (4 m.y., p>v), and Yanacocha, Peru (6 m.y., v>p). At Yerington granite dikes and ores formed in one event, at ES in 2 to 3 events spanning 3 m.y., and at Yanacocha in 6 events spanning 5 m.y. At both ES and Yanacocha, high-Al amphiboles likely crystallized at high temperature in the mid-crust and attest to deep magmas that periodically recharged the shallow chambers. At Yanacocha, these amphiboles contain anhydrite inclusions that require magmas were sulfur-rich and strongly oxidized (~NNO+2). The Ti-in-zircon geothermometer provides estimates of 920º to 620º C for zircon crystallization, and records both core to rim cooling and locally high temperature rim overgrowths. Ore-related silicic porphyries yield near-solidus crystallization temperatures of 750-650°C consistent with low zircon saturation temperatures. The latter zircons have large positive Ce/Ce* and small negative Eu/Eu*≥0.4 anomalies attesting to strongly oxidized conditions (Ballard et al., 2001), which we propose result from crystallization and SO2 loss to the magmatic-hydrothermal ore fluid (Dilles et al., 2015). The Hf, REE, Y, U, and Th contents of zircons are diverse in the magma suites, and Th/U vs Yb/Gd plots suggest a dominant role of crystal fractionation with lesser roles for both crustal contamination and mixing with high temperature deep-sourced mafic magma. Ce/Sm vs Yb/Gd plots suggest that magma REE contents at <900°C are dominated by early crystallization of hornblende and apatite, and late crystallization (~<780°C) of titanite

  2. Pressure gradients and boiling as mechanisms for localizing ore in porphyry systems

    USGS Publications Warehouse

    Cunningham, Charles G.

    1978-01-01

    Fluid inclusions in ore zones of porphyry systems indicate that extensive boiling of hydrothermal fluids accompanies deposition of ore and gangue minerals. The boiling commonly accompanied a change from a lithostatic to a hydrostatic environment during evolution of an epizonal stock. Pressure gradients near the margin of the stock can determine whether ore or only a diffuse zone of mineralization is formed. A sharp drop in pressure in an epizonal environment is more likely to cause extensive boiling than a comparable change in a deeper environment, as the slope of the boiling curve steepens with an increase 'in pressure. The drop in pressure causes the hydrothermal fluids to boil and creates a crackle (stockwork) breccia, which hosts the veinlets of gangue quartz and ore minerals. The boiling selectively partitions CO2, H2S, and HCl into the vapor phase, changing the pH, composition, ionic strength, and thus the solubility product of metal complexes in the remaining liquid and causing the ore and gangue to come out of solution. Fluid inclusions trapped from boiling solutions can exhibit several forms, depending on the physical and chemical conditions of the hydrothermal fluid from which they were trapped. In one case, inclusions when heated can homogenize to either liquid or vapor at the same temperature, which is the true boiling temperature. In another case, homogenization of various inclusions can occur through a range of temperatures. The latter case results from the trapping of mixture of liquid and vapor. Variations in salinity can result from boiling of the hydrothermal fluid, or intermittent incorporation of high-salinity fluids from the magma, or trapping of fluids of varying densities at pressure-temperature conditions above the critical point of the fluid. In places, paleopressure-temperature transition zones can be recognized by fluid-inclusion homogenization temperatures and phase relationships and by the presence of anhydrite daughter minerals

  3. Generation of porphyry copper deposits by gas-brine reaction in volcanic arcs

    NASA Astrophysics Data System (ADS)

    Blundy, Jon; Mavrogenes, John; Tattitch, Brian; Sparks, Steve; Gilmer, Amy

    2014-05-01

    Porphyry copper deposits (PCDs) are characterised by a close spatial and temporal association with small, hypabyssal intrusions of silicic magmas in volcanic arcs. PCD formation requires elevated chlorine and water to concentrate copper in magmatic hypersaline liquids (or brines), and elevated sulphur to precipitate copper-rich sulphides. These twin requirements are hard to reconcile with experimental and petrological evidence that voluminous chlorine-rich, hydrous silicic magmas, of the variety favourable to copper enrichment, lack sufficient sulphur to precipitate directly the requisite quantities of sulphides. These features are, however, consistent with observations of active volcanic arcs whereby PCDs can be viewed as roots of dome volcanoes above shallow reservoirs where silicic magmas accumulate over long time spans. During protracted periods of dormancy metal-enriched dense brines accumulate in and above the silicic reservoir through slow, low-pressure degassing. Meanwhile cogenetic volatile-rich mafic magmas and their exsolved, sulphur and CO2-rich fluids accumulate in deeper reservoirs. Periodic destabilisation of these reservoirs leads to short-lived bursts of volcanism liberating sulphurous gases, which react with the shallow-stored brines to form copper-rich sulphides and acidic vapours. We test this hypothesis with a novel set of 'porphyry in a capsule' experiments designed to simulate low-pressure (1-2 kbar) interaction of basalt-derived, sulphur-rich gases with brine-saturated, copper-bearing, but sulphur-free, granite. Experiments were run at 720-850 ° C in cold-seal apparatus with basaltic andesite, loaded with H2O and S, situated below dacite, loaded with H2O, Cl and Cu. At run conditions both compositions are substantially degassed and crystallized. S-rich gas from the basaltic andesite ascends to react with Cu-rich brines exsolved from the dacite, Our experiments reveal the direct precipitation of copper-sulphide minerals, in vugs and veins

  4. Research on remote sensing assessment technology for porphyry copper in south of Arequipa province of Peru

    NASA Astrophysics Data System (ADS)

    Yang, Rihong; Li, Zhizhong; Cheng, Xiufa; Zhao, Yuling

    2014-05-01

    The study area is located in the middle section of Andean metallogenic zone. Excellent mineralization geological conditions make it the most principal Porphyry Copper Deposits (PCDs) distribution area in southern Peru and there are several super-large PCDs for hundreds of kilometers in every direction. The regional metallogenic regularity of this area is controlled by the NNW fault parallel to the trench on the west of the South American continent. Small porphyry rocks are very common in this area (circular structure pattern in remote sensing image) with typical zoned alteration of PCD - potassic alteration, argillic alteration, phyllic alteration and propylitization (most exposed) from inside to the outside on the surface. These geologic features can be recognized and extracted by using remote sensing image data. Accordingly, the reflectivity curve of main altered minerals of the typical alteration zones of PCD was rebuilt which was corresponded to B1-B9 of ASTER satellite data, based on the altered mineral assemblages and their spectral characteristics of the typical alteration zones of PCD, and ASTER data's ability of identifying minerals with argillic alteration and carbonatite alteration. Based on the standard spectral data of USGS, We found that the information of argillic-and phyllic- altered minerals assemblages in the typical alteration zones can be extracted in the principal components analysis pattern based on ASTER B1467 while the information of propylitization altered minerals in the principal components analysis pattern based on ASTER B1348 with larger reflectivity of B9 than B8, after comparing and analyzing comprehensively the spectral curve characteristics of main altered minerals. In this method, altered minerals assemblages of argillic-and phyllic- altered zone and propylitization altered zone in this study area was extracted, and the results agree well with the distribution of known PCD. Meanwhile, remote sensing geological interpretation has

  5. The formation of Luoboling porphyry Cu-Mo deposit: Constraints from zircon and apatite

    NASA Astrophysics Data System (ADS)

    Li, Cong-ying; Hao, Xi-luo; Liu, Ji-qiang; Ling, Ming-xing; Ding, Xing; Zhang, Hong; Sun, Wei-dong

    2017-02-01

    The Luobuling porphyry Cu-Mo deposit belongs to the Late Cretaceous Zijinshan Cu-Au-Mo mineralization field in southeastern China. Due to intensive hydrothermal alteration and weathering, it is very difficult to collect fresh whole rock samples for geochemical and isotopic studies in Luobuling. Zircon and apatite are accessory minerals that are resistant to hydrothermal alterations. In this study, we compared the trace element and isotope compositions of zircon and apatite from ore-bearing and barren samples to understand the formation of the Luoboling Cu-Mo deposit. Zircon U-Pb LA-ICP-MS dating shows that the Luoboling porphyries formed at 100 Ma (100.3 ± 1.2 Ma, 100.6 ± 1.5 Ma and 98.6 ± 1.2 Ma), which belongs to the late stage mineralization of the Zijinshan mineralization field. Zhongliao porphyritic granodiorite has the same age as the deposit (99.5 ± 1.6 Ma). The age of barren Sifang granodiorite is slightly older (109.7 ± 0.8 Ma). All these zircon grains have high Ce4+/Ce3+ ratios, indicating high oxygen fugacities. The ore-bearing samples show variable εHf(t) of - 7.3 to 0.2, suggesting either heterogeneous sources or mixing of two different magmas. Interestingly, the Hf isotope composition of barren samples is systematically higher (εHf(t) of - 3.6 to 5.5), implying a lower contribution of crustal materials. The OH mole percent of apatite grains from barren samples (LBL22-03 and SF09-05) is 0.5, which is higher than that of apatite from the ore-bearing samples (LBL20-01 LBL20-02 and LBL22-02), indicating lower F, Cl contents or higher water contents in the magma. In apatite from the ore-bearing samples, Sr is high, indicating the absence of plagioclase crystallization. In contrast, barren samples have varied and lower Sr, indicating that apatite crystallization was accompanied by plagioclase. These patterns were controlled by water contents because the crystallization of plagioclase is suppressed by high water contents in magmas. It also suggests

  6. "Normal" to adakite-like arc magmatism associated with the El Abra porphyry copper deposit, Central Andes, Northern Chile

    NASA Astrophysics Data System (ADS)

    Rabbia, Osvaldo M.; Correa, Karen J.; Hernández, Laura B.; Ulrich, Thomas

    2017-03-01

    The El Abra porphyry copper deposit belongs to the Late Eocene—Early Oligocene metallogenic belt of northern Chile, which host several world-class porphyry copper deposits. Our previous geochronological work done on this deposit provides the temporal framework for petrological data interpretation. The magmatic history of the El Abra deposit lasts for 8.6 Ma and can be divided into two stages. An early period, from about 45 to 38.7 Ma, dominated by diorites and quartz monzodiorites with "normal" (non-adakite) arc geochemistry and a late period, with rocks younger than 38.7 Ma that developed adakite-like geochemistry, where equigranular granodiorites are the volumetrically dominant rock type (e.g., Clara granodiorite 38 Ma). These granodiorites are then intruded by leucocratic porphyry dikes and aplites. Most copper mineralization is associated with multiple intrusions of these younger porphyritic rocks, described as the El Abra porphyry unit, and emplaced over a 1.4 Ma period, from 37.5 to 36.1 Ma. The adakite-like geochemistry of the younger rock units (<38.7 Ma) is attested by a significant depletion in REE contents, particularly MREE and HREE (concave MREE distribution patterns), high La/Yb and Sr/Y ratios, and Na2O and Al2O3 contents, along with the absence of the Eu anomaly in normalized REE distribution patterns. The evolution of this large, long-lived magmatic system from "normal" to adakite-like arc magmatism is discussed in a tectonic context of crust overthickening due to a major orogenic episode (Incaic compressive phase). This tectonic setting may have promoted higher pressure conditions at the lower crust "hot zone" and increased the crustal residence time of derivative melts favoring extensive differentiation leading to water-rich (and oxidized?) felsic melts, where amphibole fractionation played an important role. Strontium, Nd, and Pb isotope data suggest a common mantle source for both the non-adakite and adakite-like rocks. This implies that

  7. From a long-lived upper-crustal magma chamber to rapid porphyry copper emplacement: Reading the geochemistry of zircon crystals at Bajo de la Alumbrera (NW Argentina)

    NASA Astrophysics Data System (ADS)

    Buret, Yannick; von Quadt, Albrecht; Heinrich, Christoph; Selby, David; Wälle, Markus; Peytcheva, Irena

    2016-09-01

    The formation of world class porphyry copper deposits reflect magmatic processes that take place in a deeper and much larger underlying magmatic system, which provides the source of porphyry magmas, as well as metal and sulphur-charged mineralising fluids. Reading the geochemical record of this large magmatic source region, as well as constraining the time-scales for creating a much smaller porphyry copper deposit, are critical in order to fully understand and quantify the processes that lead to metal concentration within these valuable mineral deposits. This study focuses on the Bajo de la Alumbrera porphyry copper deposit in Northwest Argentina. The deposit is centred on a dacitic porphyry intrusive stock that was mineralised by several pulses of porphyry magma emplacement and hydrothermal fluid injections. To constrain the duration of ore formation, we dated zircons from four porphyry intrusions, including pre-, syn- and post-mineralisation porphyries based on intersection relations between successive intrusion and vein generations, using high precision CA-ID-TIMS. Based on the youngest assemblages of zircon grains, which overlap within analytical error, all four intrusions were emplaced within 29 ka, which places an upper limit on the total duration of hydrothermal mineralisation. Re/Os dating of hydrothermal molybdenite fully overlaps with this high-precision age bracket. However, all four porphyries contain zircon antecrysts which record protracted zircon crystallisation during the ∼200 ka preceding the emplacement of the porphyries. Zircon trace element variations, Ti-in-zircon temperatures, and Hf isotopic compositions indicate that the four porphyry magmas record a common geochemical and thermal history, and that the four intrusions were derived from the same upper-crustal magma chamber. Trace element zoning within single zircon crystals confirms a fractional crystallisation trend dominated by titanite and apatite crystallisation. However, zircon

  8. Origin of Late Mesozoic granitoids in the newly discovered Zha-Shan porphyry Cu district, South Qinling, central China, and implications for regional metallogeny

    NASA Astrophysics Data System (ADS)

    Xie, Guiqing; Mao, Jingwen; Wang, Ruiting; Ren, Tao; Li, Jianbi; Da, Junzhi

    2015-05-01

    The newly discovered porphyry Cu deposits in the South Qinling Belt (SQB) have not been well researched as compared with the large porphyry Mo province in the southern North China Block (S-NCB), and the origin of granitoids associated with porphyry Cu mineralization in the Zha-Shan district, SQB is poorly constrained. Here, we present detailed zircon U-Pb geochronological, whole rock elemental and Sr-Nd isotopic data for important Late Mesozoic granitoid stocks associated with porphyry Cu deposits in the Zha-Shan district; these data are used to constrain the age and the source of magmas that formed these granitoids, and implication of regional metallogeny. The new zircon LA-ICPMS U-Pb ages presented here indicate that the granitoids related to porphyry Cu system at Chigou, Beishagou, Shuangyuangou and Yuanjiagou developed at 148-144 Ma, 144 Ma, 145-144 Ma and 146 Ma, respectively. These rocks are high-K calc-alkaline I-type granitoids, which are enriched in large ion lithophile elements (e.g., Th, U, and Pb) and light rare earth elements, are depleted in Nb, Ta and Ti, characterizing by wide variations in initial εNd(t) (-3.8 to -9.5), and moderate radiogenic Sr isotopes ((87Sr/86Sr)i = 0.7046 to 0.7093). These features indicate that the magmas that formed the granitoids related to porphyry Cu system in the Zha-Shan district formed as a result of variable degrees of mixing between crustal and metasomatic lithospheric mantle. The new zircon LA-ICPMS U-Pb ages in this study, combined with previous published data, suggest that regional-scale Late Jurassic to Early Cretaceous granitoid stocks, and associated porphyry Cu and Mo systems in both the S-NCB and SQB formed almost contemporaneously, with 147-139 Ma porphyry Mo deposits in the S-NCB and 148-145 Ma porphyry Cu deposits in the SQB. The Cu-related intrusions contained a greater contribution of lithospheric mantle component than the Mo-related intrusions in the East Qinling Orogeny.

  9. Origin of the Wunugetushan porphyry Cu-Mo deposit, Inner Mongolia, NE China: Constraints from geology, geochronology, geochemistry, and isotopic compositions

    NASA Astrophysics Data System (ADS)

    Zhang, Fang-Fang; Wang, Yin-Hong; Liu, Jia-Jun; Wang, Jian-Ping; Zhao, Chun-Bo; Song, Zhi-Wei

    2016-03-01

    The Wunugetushan porphyry Cu-Mo deposit is located in the southeastern margin of the Mongol-Okhotsk Orogenic Belt and in the northwestern segment of the Great Xing'an Range, NE China. The orebodies of this deposit are mainly hosted in the monzogranitic porphyry stock and in contact with the granitic porphyry dyke and biotite granite batholith. The SHRIMP zircon U-Pb dating of the granitic porphyry dyke yielded ages of 201.4 ± 3.1 Ma (2σ, MSWD = 1.5). These results indicate that the magmatism in the Wunugetushan area might have occurred at ca. 201 Ma in the early Jurassic, and that the mineralization age (ca. 181 Ma) of this deposit is later than the age of intrusive granitic porphyry in the area. Geochemically, the Wunugetushan granitoids belong to high-K calc-alkaline and shoshonitic series, enriched in K, Rb, Nd, and Pb, and depleted in Sr, Nb, Ti and P, with negative Eu anomalies. In situ Hf isotopic analyses of zircons using LA-MC-ICP-MS indicate that the εHf(t) values for zircons from a granitic porphyry sample vary from +2.4 to +11.8 and that the corresponding crustal model ages (TDMC) vary from 483 to 1088 Ma. The least-altered monzogranitic porphyry, granitic porphyry and biotite granite yielded relatively uniform εNd(t) values from -1.0 to +0.6 and low (87Sr/86Sr)i ratios ranging from 0.704387 to 0.708385. The geochemical and Sr-Nd-Hf isotopic data for the granitoids indicate that the source magma for these rocks could be derived from a juvenile lower crust. The δ34S values of sulfides show a narrow range (+0.76‰ to +3.20‰) similar to those of magmatic sulfur, further implying a lower crust origin. Based on the results of this study and the regional geodynamic evolution, it is proposed that the formation of the Wunugetushan deposit and associated granitoids should be linked to the southeastward subduction of the Mongol-Okhotsk oceanic plate beneath the Erguna Massif during the early Jurassic, and that the monzogranitic porphyry intrusions in

  10. Landsat-4 thematic mapper and thematic mapper simulator data for a porphyry copper deposit

    NASA Technical Reports Server (NTRS)

    Abrams, M. J.

    1984-01-01

    Aircraft thematic mapper (TM) data were analyzed to evaluate the potential utility of the Landsat-4 thematic mapper for geologic mapping and detection of hydrothermal alteration zones in the Silver Bell porphyry copper deposit in southern Arizona. The data allow a comparison between aircraft TV simulator data and the Landsat-4 TM satellite data which possess similar spectral bands. A color rationcomposite of 30-m pixels was resampled, in order to clearly define a number of hydroxyl bearing minerals, (kaolinite, sericite, white mica), pyrite and iron oxide/hydroxide minerals. The iron oxide minerals have diagnostic absorption bands in the 0.45 and 0.85 micron regions of the spectrum, and the hydrous minerals are characterized by an absorption in the 2.2 micron region. The position of the spectral bands allow the TM to identify regions of hydrothermal alteration without resorting to a data processing algorithm. The comparison of the aircraft and Landsat-4 TM data showed considerable agreement, and confirmed the utility of TM data for identifying hydrothermal alteration zones. Samples of some color TM images are provided.

  11. Exploration for porphyry copper deposits in Pakistan using digital processing of Landsat-1 data

    NASA Technical Reports Server (NTRS)

    Schmidt, R. G.

    1976-01-01

    Rock-type classification by digital-computer processing of Landsat-1 multispectral scanner data has been used to select 23 prospecting targets in the Chagai District, Pakistan, five of which have proved to be large areas of hydrothermally altered porphyry containing pyrite. Empirical maximum and minimum apparent reflectance limits were selected for each multispectral scanner band in each rock type classified, and a relatively unrefined classification table was prepared. Where the values for all four bands fitted within the limits designated for a particular class, a symbol for the presumed rock type was printed by the computer at the appropriate location. Drainage channels, areas of mineralized quartz diorite, areas of pyrite-rich rock, and the approximate limit of propylitic alteration were very well delineated on the computer-generated map of the test area. The classification method was used to evaluate 2,100 sq km in the Mashki Chah region. The results of the experiment show that outcrops of hydrothermally altered and mineralized rock can be identified from Landsat-1 data under favorable conditions.

  12. Hydrogeochemical prospecting for porphyry copper deposits in the tropical-marine climate of Puerto Rico

    USGS Publications Warehouse

    Miller, W.R.; Ficklin, W.H.; Learned, R.E.

    1982-01-01

    A hydrogeochemical survey utilizing waters from streams and springs was conducted in the area of two known porphyry copper deposits in the tropical-marine climate of westcentral Puerto Rico. The most important pathfinder for regional hydrogeochemical surveys is sulfate which reflects the associated pyrite mineralization. Because of increased mobility due to intense chemical weathering and the low pH environment, dissolved copper can also be used as a pathfinder for regional surveys and has the advantage of distinguishing barren pyrite from pyrite associated with copper mineralization. For follow-up surveys, the most important pathfinders are copper, sulfate, pH, zinc, and fluoride. High concentrations of dissolved copper and moderate concentrations of sulfate is a diagnostic indication of nearby sources of copper minerals. An understanding of the geochemical processes taking place in the streambeds and the weathering environment, such as the precipitation of secondary copper minerals, contributes to the interpretation of the geochemical data and the selection of the most favorable areas for further exploration. ?? 1982.

  13. Use of ERTS-1 images in the search for porphyry copper deposits in Pakistani Baluchistan

    NASA Technical Reports Server (NTRS)

    Schmidt, R. G.

    1973-01-01

    Geomorphic features related to a known porphyry copper deposit at Saindak, western Chagai District, Pakistan, are easily distinguished on ERTS-1 images. New geologic information from the images was used in conjunction with known geology to evaluate one previously known prospect area and to suggest two additional ones, but no new prospects were recognized on the basis of the images alone. The study also showed that Saindak-type deposits are not likely to be present in some extensive areas of the Chagai District. The Saindak deposit is in an area of relatively easily eroded folded sedimentary and volcanic rocks. The deposit is characterized by an elongate zone of easily eroded sulfide-rich rock surrounded by this rim and the central sulfide-rich valley are conspicuous features on the images. Swarms of dikes are probably useful for distinguishing real rims from other resistant rock types, but there is no expression of them on the image, although they are easily seen on aerial photographs of the Saindak rim.

  14. Multiple Sources In Ultrapotassic Arc Magmas Inferred From Combined Microthermometry And In-Situ Chemical Analysis Of Melt Inclusions In Olivine And Clinopyroxene Phenocrysts From Batu Tara Volcano, Indonesia

    NASA Astrophysics Data System (ADS)

    Herrin, J. S.; Nikogosian, I. K.; van Bergen, M. J.; Mason, P. R.

    2001-12-01

    Batu Tara is an active, leucite-normative, ultrapotassic volcano located approximately 75 km behind the main magmatic front of the eastern Sunda arc, Indonesia. Clinopyroxene, olivine, plagioclase, leucite, Ti-magnetite, minor apatite and occasional biotite occur as phenocrysts. The exact mechanism for genesis of ultrapotassic arc rocks remains elusive, particularly in island arc settings. Concise determination of primary magma chemistry is often impeded by complex histories of crystallization and magma mixing. Melt inclusions in olivine and pyroxene phenocrysts from Batu Tara have been investigated by high-temperature microthermometry, EPMA, and LA-ICP-MS to constrain parent magma composition and shed light on the genesis of ultrapotassic magmas in island arc settings. Variation in homogenization temperature, major and trace element composition, and volatile content correlate with petrographic observation of three distinct populations of olivine phenocrysts which can be distinguished by the presence or absence of apatite mineral inclusions and CO2 fluid inclusions. Clinopyroxenes commonly exhibit pronounced chemical zonation with individual zones preserving melt inclusions of unique composition, indicating that these phenocrysts were involved in complex mixing processes and repeatedly subject to end-member magma compositions. Melt inclusions preserve a record of; (1) Early spinel, olivine and clinopyroxene crystallization, followed by later crystallization of abundant apatite; (2) Exsolution of volatile species (S, CO2, Cl, H2O) during magma degassing; (3) Mixing of multiple magmas, originating from chemically and likely genetically distinct sources, and; (4) A significant but variable component of fluid addition to the magma source inferred from systematics of incompatible trace elements.

  15. Lead isotope compositions of Late Cretaceous and early Tertiary igneous rocks and sulfide minerals in Arizona: Implications for the sources of plutons and metals in porphyry copper deposits

    USGS Publications Warehouse

    Bouse, R.M.; Ruiz, J.; Titley, S.R.; Tosdal, R.M.; Wooden, J.L.

    1999-01-01

    Porphyry copper deposits in Arizona are genetically associated with Late Cretaceous and early Tertiary igneous complexes that consist of older intermediate volcanic rocks and younger intermediate to felsic intrusions. The igneous complexes and their associated porphyry copper deposits were emplaced into an Early Proterozoic basement characterized by different rocks, geologic histories, and isotopic compositions. Lead isotope compositions of the Proterozoic basement rocks define, from northwest to southeast, the Mojave, central Arizona, and southeastern Arizona provinces. Porphyry copper deposits are present in each Pb isotope province. Lead isotope compositions of Late Cretaceous and early Tertiary plutons, together with those of sulfide minerals in porphyry copper deposits and of Proterozoic country rocks, place important constraints on genesis of the magmatic suites and the porphyry copper deposits themselves. The range of age-corrected Pb isotope compositions of plutons in 12 Late Cretaceous and early Tertiary igneous complexes is 206Pb/204Pb = 17.34 to 22.66, 207Pb/204Pb = 15.43 to 15.96, and 208Pb/204Pb = 37.19 to 40.33. These Pb isotope compositions and calculated model Th/U are similar to those of the Proterozoic rocks in which the plutons were emplaced, thereby indicating that Pb in the younger rocks and ore deposits was inherited from the basement rocks and their sources. No Pb isotope differences distinguish Late Cretaceous and early Tertiary igneous complexes that contain large economic porphyry copper deposits from less rich or smaller deposits that have not been considered economic for mining. Lead isotope compositions of Late Cretaceous and early Tertiary plutons and sulfide minerals from 30 metallic mineral districts, furthermore, require that the southeastern Arizona Pb province be divided into two subprovinces. The northern subprovince has generally lower 206Pb/204Pb and higher model Th/U, and the southern subprovince has higher 206Pb/204Pb and

  16. Geologic and geochemical insights into the formation of the Taiyangshan porphyry copper–molybdenum deposit, Western Qinling Orogenic Belt, China

    USGS Publications Warehouse

    Kun-Feng Qiu,; Taylor, Ryan D.; Yao-Hui Song,; Hao-Cheng Yu,; Kai-Rui Song,; Nan Li,

    2016-01-01

    Taiyangshan is a poorly studied copper–molybdenum deposit located in the Triassic Western Qinling collisional belt of northwest China. The intrusions exposed in the vicinity of the Taiyangshan deposit record episodic magmatism over 20–30 million years. Pre-mineralization quartz diorite porphyries, which host some of the deposit, were emplaced at 226.6 ± 6.2 Ma. Syn-collisional monzonite and quartz monzonite porphyries, which also host mineralization, were emplaced at 218.0 ± 6.1 Ma and 215.0 ± 5.8 Ma, respectively. Mineralization occurred during the transition from a syn-collisional to a post-collisional setting at ca. 208 Ma. A barren post-mineralization granite porphyry marked the end of post-collisional magmatism at 200.7 ± 5.1 Ma. The ore-bearing monzonite and quartz monzonite porphyries have a εHf(t) range from − 2.0 to + 12.5, which is much more variable than that of the slightly older quartz diorite porphyries, with TDM2 of 1.15–1.23 Ga corresponding to the positive εHf(t) values and TDM1 of 0.62–0.90 Ga corresponding to the negative εHf(t) values. Molybdenite in the Taiyangshan deposit with 27.70 to 38.43 ppm Re suggests metal sourced from a mantle–crust mixture or from mafic and ultramafic rocks in the lower crust. The δ34S values obtained for pyrite, chalcopyrite, and molybdenite from the deposit range from + 1.3‰ to + 4.0‰, + 0.2‰ to + 1.1‰, and + 5.3‰ to + 5.9‰, respectively, suggesting a magmatic source for the sulfur. Calculated δ18Ofluid values for magmatic K-feldspar from porphyries (+ 13.3‰), hydrothermal K-feldspar from stockwork veins related to potassic alteration (+ 11.6‰), and hydrothermal sericite from quartz–pyrite veins (+ 8.6 to + 10.6‰) indicate the Taiyangshan deposit formed dominantly from magmatic water. Hydrogen isotope values for hydrothermal sericite ranging from − 85 to − 50‰ may indicate that magma degassing progressively depleted residual liquid in

  17. Re-Os isotopic and trace element compositions of pyrite and origin of the Cretaceous Jinchang porphyry Cu-Au deposit, Heilongjiang Province, NE China

    NASA Astrophysics Data System (ADS)

    Zhang, Peng; Huang, Xiao-Wen; Cui, Bin; Wang, Bo-Chao; Yin, Yi-Fan; Wang, Jing-Rui

    2016-11-01

    The Jinchang Cu-Au deposit in Northeast China contains more than 76 tons of Au and 4683 tons of Cu with average ore grades of 11.34 g/t Au and 1.44% Cu. The deposit is typical of porphyry types and consists of gold orebodies mainly hosted in a ∼113 Ma granitic porphyry and breccia pipes within the porphyry intrusion. Mineralization is closely associated with early potassic alteration and late phyllic alteration. Pyrite is the main Au-bearing mineral and contains 1.48-18.9 ppb Re and 11.4-38 ppt common Os. Extremely low common Os concentrations and high Re/Os ratios are indicative of derivation of ore-forming materials from the crust. Low Re in pyrite from the Jinchang deposit may indicate a mixing source of mantle and crust or a crustal source. Five Re-Os isotopic analyses yield a model 1 isochron age of 114 ± 22 Ma (2σ, MSWD = 0.15), similar to the age of the host porphyry. Pyrite contains detectable Co, Ni, Cu, Zn, As, Ag, Au, Sb, Pb and Bi. Pyrite has Co/Ni ratios similar to that of volcanogenic and hydrothermal sulfide deposits, indicating a magmatic-hydrothermal origin, and has Au and As contents similar to that of porphyry-epithermal systems. Pyrite grains from potassic and phyllic alteration stages have different trace element contents, reflecting the evolution of ore-forming fluids from magmatic dominated to magmatic mixed with meteoric water. In combination with regional geology, our new results are suggestive of origin of the Jinchang Cu-Au deposit from contemporary intrusions of granitic porphyries related to the Early Cretaceous subduction of the Paleo-Pacific plate.

  18. Fluid inclusion characteristics and molybdenite Re-Os geochronology of the Qulong porphyry copper-molybdenum deposit, Tibet

    NASA Astrophysics Data System (ADS)

    Li, Yang; Selby, David; Feely, Martin; Costanzo, Alessandra; Li, Xian-Hua

    2016-04-01

    The Qulong porphyry copper and molybdenum deposit is located at the southwest margin of the Lhasa Terrane and in the eastern region of the Gangdese magmatic belt. It represents China's largest porphyry copper system, with ˜2200 million tonnes of ore comprising 0.5 % Cu and 0.03 % Mo. The mineralization is associated with Miocene granodiorite, monzogranite and quartz-diorite units, which intruded into Jurassic volcanic units in a post-collisional (Indian-Asian) tectonic setting. Field observations and core logging demonstrate the alteration and mineralization at Qulong are akin to typical porphyry copper systems in subduction settings, which comprise similar magmatic-hydrothermal, potassic, propylitic and phyllic alteration assemblages. Molybdenite Re-Os geochronology confirms the relative timeframe defined by field observations and core logging and indicates that the bulk copper and molybdenum at Qulong were deposited within 350,000 years: between 16.10 ± 0.06 [0.08] (without and with decay constant uncertainty) and 15.88 ± 0.06 [0.08] Ma. This duration for mineralization is in direct contrast to a long-lived intrusive episode associated with mineralization based on previous zircon U-Pb data. Our fluid inclusion study indicates that the ore-forming fluid was oxidized and contained Na, K, Ca, Fe, Cu, Mo, Cl and S. The magmatic-hydrothermal transition occurred at ˜425 °C under lithostatic pressure, while potassic, propylitic and phyllic alteration occurred at hydrostatic pressure with temperature progressively decreasing from 425 to 280 °C. The fluid inclusion data presented here suggests that there has been ˜2.3 km of erosion at Qulong after its formation, and this erosion may be related to regional uplift of the Lhasa Terrane.

  19. Fluid inclusion characteristics and molybdenite Re-Os geochronology of the Qulong porphyry copper-molybdenum deposit, Tibet

    NASA Astrophysics Data System (ADS)

    Li, Yang; Selby, David; Feely, Martin; Costanzo, Alessandra; Li, Xian-Hua

    2017-02-01

    The Qulong porphyry copper and molybdenum deposit is located at the southwest margin of the Lhasa Terrane and in the eastern region of the Gangdese magmatic belt. It represents China's largest porphyry copper system, with ˜2200 million tonnes of ore comprising 0.5 % Cu and 0.03 % Mo. The mineralization is associated with Miocene granodiorite, monzogranite and quartz-diorite units, which intruded into Jurassic volcanic units in a post-collisional (Indian-Asian) tectonic setting. Field observations and core logging demonstrate the alteration and mineralization at Qulong are akin to typical porphyry copper systems in subduction settings, which comprise similar magmatic-hydrothermal, potassic, propylitic and phyllic alteration assemblages. Molybdenite Re-Os geochronology confirms the relative timeframe defined by field observations and core logging and indicates that the bulk copper and molybdenum at Qulong were deposited within 350,000 years: between 16.10 ± 0.06 [0.08] (without and with decay constant uncertainty) and 15.88 ± 0.06 [0.08] Ma. This duration for mineralization is in direct contrast to a long-lived intrusive episode associated with mineralization based on previous zircon U-Pb data. Our fluid inclusion study indicates that the ore-forming fluid was oxidized and contained Na, K, Ca, Fe, Cu, Mo, Cl and S. The magmatic-hydrothermal transition occurred at ˜425 °C under lithostatic pressure, while potassic, propylitic and phyllic alteration occurred at hydrostatic pressure with temperature progressively decreasing from 425 to 280 °C. The fluid inclusion data presented here suggests that there has been ˜2.3 km of erosion at Qulong after its formation, and this erosion may be related to regional uplift of the Lhasa Terrane.

  20. Hydrothermal alteration and its effects on the magnetic properties of Los Pelambres, a large multistage porphyry copper deposit

    NASA Astrophysics Data System (ADS)

    Tapia, Joseline; Townley, Brian; Córdova, Loreto; Poblete, Fernando; Arriagada, César

    2016-09-01

    The Los Pelambres porphyry copper deposit is located 190 km north of Santiago, Chile. A paleomagnetic and mineralogical study was conducted at this deposit to determine the effects of hydrothermal alteration on the magnetic properties and minerals of rocks within the deposit when compared to the surrounding country rock. In the Los Pelambres deposit, magnetic properties of rocks are carried by titano-hematite and titano-magnetite solid solution minerals, where the former commonly indicates the exsolution of rutile. Magnetic minerals of intrusive rocks from the greater Los Pelambres region show that magmatic titano-magnetites and magnetites are the main magnetization carriers. The hydrothermal fluid associated with rutile exsolution textures could have played an important role in the mineralization of Cu in this deposit. The paleomagnetic properties in the Los Pelambres deposit can be divided in three main groups: (i) HMRG (high magnetic remanence group), (ii) HMSG (high magnetic susceptibility group), and (iii) LMSG (low magnetic susceptibility/remanence group). In-situ magnetic properties of the HMSG and LMSG are similar to the formations and units present regionally, however HRMG samples clearly differ from the country rocks. The high variability of in-situ magnetic properties presented in the Los Pelambres deposit has also been characteristic of other porphyry copper deposits in Chile (e.g., Chuquicamata and El Teniente). Regarding the field of exploration geophysics and porphyry copper deposits, this study suggests that phyllic, chloritic, and potassic alterations are related to low, intermediate, and high in-situ NRM, respectively, suggesting that geophysical methods must target a noisy magnetic signal depending on the scale of the study. The knowledge and results obtained are especially meaningful because magnetic surveys conducted for exploration do not commonly allow for the detection of ore mineralization.

  1. Cretaceous subduction-related magmatism and associated porphyry-type Cu-Mo prospects in the Eastern Pontides, Turkey: New constraints from geochronology and geochemistry

    NASA Astrophysics Data System (ADS)

    Delibaş, Okan; Moritz, Robert; Ulianov, Alexey; Chiaradia, Massimo; Saraç, Cem; Revan, Kemal M.; Göç, Deniz

    2016-04-01

    This study focuses on the Elbeyli-Ordu, Emeksen-Giresun, Güzelyayla-Trabzon and Ulutaş-Ispir porphyry-type prospects located in the Eastern Pontides, Turkey. Our new LA-ICP-MS U-Pb zircon age data reveal that the Elbeyli-Ordu Mo-Cu mineralization is hosted by a 77.0 ± 1.3 Ma-old monzonite/monzodiorite with a shoshonitic character. The Emeksen Mo mineralization, located ~ 40 km southeast of the Elbeyli-Ordu prospect, consists of NW- and NE-striking quartz veins crosscutting a high-K calc-alkaline to shoshonitic granite dated at 78.5 ± 0.8 Ma, a granodiorite dated at 78.7 ± 0.5 Ma and porphyry granite dated at 77.7 ± 0.5 Ma. The Güzelyayla porphyry Cu-Mo prospect consists of a stockwork-type Cu-Mo mineralization crosscutting a calc-alkaline 81.4 ± 1.1 Ma-old dacite porphyry and Late Cretaceous calc-alkaline andesite. The Ispir-Ulutaş mineralization is hosted within a highly sericitized 131.1 ± 0.9 Ma-old quartz-porphyry that intruded into a 132.9 ± 0.6 Ma-old calc-alkaline granite porphyry. Our new U-Pb zircon ages, lithogeochemical and radiogenic isotopic data of the host rocks associated with the porphyry-type prospects in the Eastern Pontides indicate that they formed in an arc-related environment during Cretaceous subduction of the Neotethys Ocean, and the Ispir-Ulutaş prospect is attributed to the main stage of the northward subduction of the Neotethys during the Early Cretaceous. We conclude that the Güzelyayla and Emeksen hydrothermal systems were formed during a transitional compressional to extensional tectonic evolution, whereas the Late Cretaceous Elbeyli hydrothermal system was emplaced during an extensional arc magmatic event. Highly-oxidized, high-K calc-alkaline to shoshonitic magmas at Emeksen and Elbeyli were derived from a metasomatized, heterogeneous and enriched lithospheric mantle, with variable degrees of partial melting of the mantle wedge and variable crustal contamination. Mixing/mingling processes between mafic magmas derived

  2. Zircon petrochronology reveals the temporal link between porphyry systems and the magmatic evolution of their hidden plutonic roots (the Eocene Coroccohuayco deposit, Peru)

    NASA Astrophysics Data System (ADS)

    Chelle-Michou, Cyril; Chiaradia, Massimo; Ovtcharova, Maria; Ulianov, Alexey; Wotzlaw, Jörn-Frederik

    2014-06-01

    We present zircon geochronologic (LA-ICPMS and ID-TIMS), trace element and Hf isotopic evidence for a complex evolution of the plutonic roots of the Eocene Coroccohuayco porphyry system, southern Peru. LA-ICPMS U-Pb dating has initially been carried out to optimize grain selection for subsequent high-precision ID-TIMS dating and to characterize crustal assimilation (xenocrystic cores). This combined in-situ and whole-grain U-Pb dating of the same grains has been further exploited to derive a robust temporal interpretation of the complex magmatic system associated with the Coroccohuayco porphyry-skarn deposit. Our data reveal that a heterogeneous gabbrodioritic complex was emplaced at ca. 40.4 Ma and was followed by a nearly 5 Ma-long magmatic lull until the emplacement of dacitic porphyry stocks and dykes associated with the mineralizing event at ca. 35.6 Ma. However, at the sample scale, zircons from the porphyries provide insight into a 2 Ma-long lived “hidden” magmatism (probably at 4-9 km paleodepth) prior to porphyry intrusion and mineralization for which no other evidence can be found on the surface today. These dates together with zircon trace element analysis and Hf isotopes argue for the development of a long-lived magmatic system dominated by amphibole fractionation with an increasing amount of crustal assimilation and the development of a large and sustained thermal anomaly. The system was probably rejuvenated at an increasing rate from 37.5 to 35.6 Ma with injection of fresh and oxidized magma from the lower crust, which caused cannibalism and remelting of proto-plutons. The porphyry intrusions at Coroccohuayco were emplaced at the peak thermal conditions of this upper crustal magma chamber, which subsequently cooled and expelled ore fluids. Zircon xenocrysts and Hf isotopes in the porphyritic rocks suggest that this large upper crustal system evolved at stratigraphic levels corresponding to Triassic sediments similar to the Mitu group that may be

  3. Table Mountain Shoshonite Porphyry Lava Flows and Their Vents, Golden, Colorado

    USGS Publications Warehouse

    Drewes, Harald

    2008-01-01

    During early Paleocene time shoshonite porphyry lava was extruded from several plugs about 5 km north of Golden, Colo., to form lava flows intercalated in the upper part of the Denver Formation. These flows now form the caps of North and South Table Mountains. Detailed field and petrographic studies provide insights into magma development, linkage between vents and flows, and the history of the lava flows. The magma was derived from a deep (mantle) source, was somewhat turbulent on its way up, paused on its way up in a shallow granite-hosted chamber, and near the surface followed the steep Golden fault and the thick, weak, steeply dipping Upper Cretaceous Pierre Shale. At the surface the lava flowed out of several plug and dike vents in a nonexplosive manner, four times during a span of about 1 m.y. Potassium-rich material acquired in the shallow chamber produced distinctive textures and mineral associations in the igneous rocks. Lava flows 1 (the lowest) and 2 are channel deposits derived from the southeastern group of intrusions, and flow 1 (a composite, multiple-tongued flow) lies about 50 m below the capping flows. Provisionally, the unit termed flow 1 is considered to include older, felty-textured flows that are distinguished from a blocky-textured unit, flow 1a. Flow 2, newly recognized in this study, lies immediately beneath the capping flows. Lava flows 3 and 4, more voluminous than the earlier ones, were derived from a plug vent 1?2 km farther north-northwest and flowed south-southeast across a broad alluvial plain. This plug is a composite body; the rim phase fed flow 3, and the core phase was the source of flow 4. During the time between the effusion of the four flows, the composition of the shoshonite porphyry magma changed subtly; the later flows contain more alkali, as shown by higher proportions of sanidine. On North Table Mountain, lava flows 3 and 4 form an elongate tumulus above a stream channel that carried water at the time of their eruption. On

  4. Geochemical element mobility during the hydrothermal alteration in the Tepeoba porphyry Cu-Mo-Au deposits at Balikesir, NW Turkey

    NASA Astrophysics Data System (ADS)

    Abdelnasser, Amr; Kiran Yildirim, Demet; Doner, Zeynep; Kumral, Mustafa

    2016-04-01

    The Tepeoba porphyry Cu-Mo-Au deposit represents one of the important copper source and mineral deposits in the Anatolian tectonic belt at Balikesir province, NW Turkey. It considered as a vein-type deposit locally associated with intense hydrothermal alteration within the brecciation, quartz stockwork veining, and brittle fracture zones in the main host rock that represented by hornfels, as well as generally related to the shallow intermediate to silicic intrusive Eybek pluton. Based on the field and geologic relationships and types of ore mineral assemblages and the accompanied alteration types, there are two mineralization zones; hypogene (primary) and oxidation/supergene zones are observed associated with three alteration zones; potassic, phyllic, and propylitic zones related to this porphyry deposit. The phyllic and propylitic alterations locally surrounded the potassic alteration. The ore minerals related to the hypogene zone represented by mostly chalcopyrite, Molybdenite, and pyrite with subordinate amount of marcasite, enargite, and gold. On the other hand they include mainly cuprite with chalcopyrite, pyrite and gold as well as hematite and goethite at the oxidation/supergene zone. This study deals with the quantitative calculations of the mass/volume changes (gains and losses) of the major and trace elements during the different episodes of alteration in this porphyry deposit. These mass balance data reveal that the potassic alteration zone that the main Cu- and Mo-enriched zone, has enrichment of K, Si, Fe, and Mg, and depletion of Na referring to replacement of plagioclase and amphibole by K-feldspar, sericite and biotite. While the propylitic alteration that is the main Mo- and Au-enriched zone is accompanied with K and Na depletion with enrichment of Si, Fe, Mg, and Ca forming chlorite, epidote, carbonate and pyrite. On the other hand the phyllic alteration that occurred in the outer part around the potassic alteration, characterized by less amount

  5. Methane origin and oxygen-fugacity evolution of the Baogutu reduced porphyry Cu deposit in the West Junggar terrain, China

    NASA Astrophysics Data System (ADS)

    Shen, Ping; Pan, HongDi

    2015-12-01

    Most porphyry copper deposits worldwide contain magnetite, hematite, and anhydrite in equilibrium with hypogene copper-iron sulfides (chalcopyrite, bornite) and have fluid inclusions with CO2 >> CH4 that are indicative of high fO2. In contrast, the Baogutu porphyry Cu deposit in the West Junggar terrain (Xinjiang, China) lacks hematite and anhydrite, contains abundant pyrrhotite and ilmenite in equilibrium with copper-iron sulfides (chalcopyrite), and has fluid inclusions with CH4 >> CO2 that are indicative of low fO2. The mineralized intrusive phases at Baogutu include the main-stage diorite stock and minor late-stage diorite porphyry dikes. The main-stage stock underwent fractional crystallization and country-rock assimilation-contamination, and consists of dominant diorite and minor gabbro and tonalite porphyry. The country rocks contain organic carbons (0.21-0.79 wt.%). The δ13CvPDB values of the whole rocks (-23.1 to -25.8 ‰) in the wall rocks suggest a sedimentary organic carbon source. The δ13CvPDB values of CH4 (-28.2 to -36.0 ‰) and CO2 (-6.8 to -20.0 ‰) in fluid inclusions require an organic source of external carbon and equilibration of their Δ13CCO2-CH4 values (8.2-25.0 ‰) at elevated temperatures (294-830 °C) suggesting a significant contribution of thermogenic CH4. Mineral composition data on the main-stage intrusions, such as clinopyroxene, hornblende, biotite, magnetite, ilmenite, sphene, apatite, and pyrrhotite, suggest that the primary magma at Baogutu was oxidized and became reduced after emplacement by contamination with country rocks. Mineral compositions and fluid inclusion gas compositions suggest that the redox state of the system evolved from log fO2 > FMQ + 1 in the magma stage, to log fO2 < FMQ as a consequence of country rocks assimilation-contamination, to log fO2 > FMQ in the hydrothermal stage. Though oxidized magma was emplaced initially, assimilation-contamination of carbonaceous country rocks decreased its fO2 such that

  6. Sequential extraction techniques applied to a porphyry copper deposit in the basin and range province

    USGS Publications Warehouse

    Filipek, L.H.; Theobald, P.K.

    1981-01-01

    Samples of minus-80-mesh (<180 ??m) stream sediment, rock containing exposed fracture coatings, and jarosite and chrysocolla were collected from an area surrounding the North Silver Bell porphyry Cu deposit near Tucson, Arizona. The samples were subjected to a series of extractions in a scheme originally designed for use on samples from humid or sub-humid environments, in which the following fractions can effectively be separated: (1) carbonates and exchangeable metals; (2) Mn oxides; (3) organic compounds and sulfides; (4) hydrous Fe oxides; and (5) residual crystalline minerals. Jarosite and chrysocolla, two major minerals of the North Silver Bell area, were found to dissolve over two or more steps of the extraction scheme. The results represent only a limited number of samples from one copper deposit. Nevertheless, they do suggest that in a semiarid to arid environment, where mechanical dispersion of such minerals predominates, uncritical assignment of unique phases, such as Mn oxides or organics to a given extraction would lead to false interpretations of weathering processes. However, the relative proportions of elements dissolved in each step of the jarosite and chrysocolla extractions could be used as a "fingerprint" for recognition of the presence of these two minerals in the stream-sediment and rock samples. The relative abundance of hydrous Fe oxide and jarosite and the alteration zoning could be mapped using data from jarosite and chrysocolla extractions. Manganese oxides were also found to have a greater influence on Zn than on Cu or Pb during supergene alteration. The rapid change in relative importance of the first (1M-acetic acid) extraction for Cu, Zn, and Pb near the mineralized zone suggested the occurrence of minor hydromorphic processes within the stream sediments. Thus, the acetic acid extraction proved the most effective for pinpointing mineralization in sediments. In contrast, the residual fraction had the longest dispersion train, suggesting

  7. Fluid Inclusion Characteristics of Domaniç (Kütahya) Porphyry Cu-Mo Mineralization

    NASA Astrophysics Data System (ADS)

    Sendir, H.; Sarıiz, K.; Bozkaya, G.

    2012-04-01

    The study area is located at 30 km northwest of Domaniç (Kütahya) and covers on approximately 250 square kilometers. The Devonian (Paleozoic) schists which are composed of gneiss, mica schist and chlorite schist is the oldest unit of the study area. This units are overlain unconformably by the Permian Allıkaya Marbles. Eocene granodioritic intrusives cut other rock series and located as a batholite. Magmatic units present porphyric and holocrystalline textures. Granodioritic intrusions are represented by tonalite, tonalite porphyr, granodiorite, granodiorite porphyr, granite, diorite, diorite porphyries. Potassic, phyllitic and prophyllitic hydrothermal alteration zones are determined in host rocks and wallrocks. Mineralizations are observed as disseminated, and stockwork types within the granodioritic rocks. Ore minerals are pyrotine, pyrite, chalcopyrite, molybdenite, rutile, bornite, sphalerite, marcasite and limonite. Geochemically, it is of sub-alkaline affinity, belongs to the high-K, calc-alkaline series and displays features of typical I-type affinity. They show enrichment in large-ion lithophile elements (LIL) and depletion Nb and Ti indicating a subduction zone related magmatic signature for their origin. Fluid inclusion assemblages (FIAs) were measured from quartz using a Linkam THMS-600 heating/cooling stage. The inclusions contain two-phase aqueous fluids (L+V) at room temperature. All fluid inclusions belong to the H2O- NaCl-CaCl2 system. Fluid inclusion microthermometry in the ore deposits suggest two main hydrothermal fluids, with modal homogenization temperatures and salinities (wt. % equivalent NaCl): (a) between 380.2o 140.7oC and ~22.3 - 13.1 %, (b) 75.2o -128.7oC and between ~10.8 - 9.2 %, respectively.

  8. Uplift and submarine formation of some Melanesian porphyry copper deposits: Stable isotope evidence

    USGS Publications Warehouse

    Chivas, A.R.; O'Neil, J.R.; Katchan, G.

    1984-01-01

    Hydrogen and oxygen isotope analyses of sericites and kaolinites from four young porphyry copper deposits (Ok Tedi (1.2 Ma) and Yandera (6.5 Ma), Papua New Guinea; Koloula (1.5 Ma), Solomon Islands; and Waisoi (<5 Ma), Fiji) indicate that the fluids from which these minerals precipitated were of mixed magmatic and non-magmatic sources. The non-magmatic component of the fluid from the island arc deposits (Koloula, Waisoi) was ocean water. For Ok Tedi, the non-magmatic component was a meteoric water with an isotopic composition different from that of the present meteoric water in the region. The isotopic signature of the former meteoric water is consistent with a surface elevation of 200 m a.s.l. or less at the time of mineralization. The deposit was later exposed and supergene kaolinitization commenced at approximately 1200 m a.s.l. Uplift and erosion has continued to the present at which time the elevation of the exposed deposit is 1800 m a.s.l. This rate of uplift is consistent with that known from other geological evidence. If the rate of uplift were approximately constant during the last 1.2 Ma, the age of supergene enrichment can be dated at approximately 0.4 Ma B.P. Similarly, influx of meteoric water at Yandera occurred when the ground surface above the deposit was at an elevation of approximately 600 m a.s.l. The deposit's present elevation is 1600 m a.s.l. In this case a total uplift of approximately 2.2 km is indicated, with removal of 1.2 km of overburden by erosion. ?? 1984.

  9. The Alapaevsk-Sukhoi Log porphyry copper zone, Middle Urals: The U-Pb age of productive magmatism

    NASA Astrophysics Data System (ADS)

    Grabezhev, A. I.; Ronkin, Yu. L.; Puchkov, V. N.; Korovko, A. V.; Gerdes, A.; Azovskova, O. B.; Pribavkin, S. V.

    2014-12-01

    The Alapaevsk-Sukhoi Log zone about 100 km long and 3-10 km wide with numerous porphyry copper occurrences and small deposits is located in the eastern part of the East Ural volcanic megazone, Middle Urals. The long evolution of productive magmatism (according to the U-Pb (SHRIMP-II and LA-ICP-MS age of zircon) and its rejuvenation are established from the north and the south (Ma): from 411 ± 3 (Yalunina Gora pluton, town of Alapaevsk) to 404-406 ± 3 (Altynai-Artemovsk pluton, town of Artemovsk) and to 397 ± 4 (porphyric rhyodacites of the Shata area, town of Sukhoi Log). The K2O content in productive quartz diorites is 0.4-0.7, 0.8-1.2, and 0.4-0.7 wt %, respectively. The Mo-Cu porphyry occurrences are abundant in the Altynai-Artemovsk area. The granitic rocks of the quartz dioritic East Artemovsk pluton, which was recently found, are sericitized and contain significant sulfide mineralization. The structural position, age (365 ± 39 Ma, Rb-Sr errochron), composition of granitic rocks, and its mineralization are similar to those of the large (1.7 Mt Cu) Mikheevka deposit (U-Pb SHRIMP-II age of zircon is 356 ± 6 Ma) in the South Urals.

  10. Gold-Silver mineralization in porphyry-epithermal systems of the Baimka trend, western Chukchi Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Nikolaev, Yu. N.; Baksheev, I. A.; Prokofiev, V. Yu.; Nagornaya, E. V.; Marushchenko, L. I.; Sidorina, Yu. N.; Chitalin, A. F.; Kal'ko, I. A.

    2016-07-01

    Mineralogical, fluid inclusion, and geochemical studies of precious metal mineralization within the Baimka trend in the western Chukchi Peninsula have been preformed. Porphyry copper-molybdenum-gold deposits and prospects of the Baimka trend are spatially related to monzonitic rocks of the Early Cretaceous Egdygkych Complex. Four types of precious metal-bearing assemblages have been identified: (1) chalcopyrite + bornite + quartz with high-fineness native gold enclosed in bornite, (2) low-Mn dolomite + quartz + sulfide (chalcopyrite, sphalerite, galena, tennantite-tetrahedrite) ± tourmaline with low-fineness native gold and hessite, (3) rhodochrosite + high-Mn dolomite + quartz + sulfide (chalcopyrite, sphalerite, galena, tennantite- tetrahedrite) with low-fineness native gold, electrum, acanthite, Ag and Au-Ag tellurides, and Ag sulfosalts, and (4) calcite + quartz + sulfide (chalcopyrite, sphalerite, galena) with low-fineness native gold, Ag sulfides and selenides, and Ag-bearing sulfosalts. Study of fluid inclusions from quartz, sphalerite, and fluorite have revealed that hydrothermal ores within the Baimka trend precipitated from fluids with strongly variable salinity at temperatures and pressures ranging from 594 to 104°C and from 1200 to 170 bar, respectively. An indicator of vertical AgPbZn/CuBiMo geochemical zoning is proposed. The value range of this indicator makes it possible to estimate the erosion level of the porphyry-epithermal system. The erosion level of the Baimka deposits and prospects deepens in the following order: Vesenny deposit → Pryamoi prospect → Nakhodka prospect → Peschanka deposit → III Vesenny prospect.

  11. The transition from porphyry- to epithermal-style gold mineralization at Ladolam, Lihir Island, Papua New Guinea: a reconnaissance study

    NASA Astrophysics Data System (ADS)

    Müller, Daniel; Kaminski, Klaus; Uhlig, Stephan; Graupner, Torsten; Herzig, Peter M.; Hunt, Steve

    2002-02-01

    The exceptionally large gold resource at Ladolam (>1,300 metric tons of gold), Lihir Island, resulted from the transition of an early-stage, low-grade porphyry gold system to a low-sulfidation epithermal gold event. This transition was probably triggered by rapid decompression during the partial slope failure of Luise stratovolcano and accompanied by the ingress of seawater. The original porphyry stage is indicated by remnant hydrothermal breccia clasts of strongly biotite-magnetite altered monzodiorite with disseminated pyrite ± chalcopyrite and poorly developed pyrite ± quartz stockwork veins. The breccias are overprinted by biotite-magnetite alteration and their matrix is strongly mineralized with disseminated auriferous pyrite. The breccias are cut by late-stage epithermal quartz-chalcedony-illite-adularia-pyrite veins and associated illite-adularia alteration that locally contain bonanza gold grades of up to 120 g/t. Isotope data suggest a magmatic source of sulfur in the gold-bearing fluids at Ladolam. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00126-001-0230-y

  12. Geochemical, microtextural and petrological studies of the Samba prospect in the Zambian Copperbelt basement: a metamorphosed Palaeoproterozoic porphyry Cu deposit.

    NASA Astrophysics Data System (ADS)

    Master, Sharad; Mirrander Ndhlovu, N.

    2015-04-01

    Ever since Wakefield (1978, IMM Trans., B87, 43-52) described a porphyry-type meta-morphosed Cu prospect, the ca 50 Mt, 0.5% Cu Samba deposit (12.717°S, 27.833°E), hosted by porphyry-associated quartz-sericite-biotite schists in northern Zambia, there has been controversy about its origin and significance. This is because it is situated in the basement to the world's largest stratabound sediment-hosted copper province, the Central African Copperbelt, which is hosted by rocks of the Neoproterozoic Katanga Supergroup. Mineralization in the pre-Katangan basement has long played a prominent role in ore genetic models, with some authors suggesting that basement Cu mineralization may have been recycled into the Katangan basin through erosion and redeposition, while others have suggested that the circulation of fluids through Cu-rich basement may have leached out the metals which are found concentrated in the Katangan orebodies. On the basis of ca 490-460 Ma Ar-Ar ages, Hitzman et al. (2012, Sillitoe Vol., SEG Spec. Publ., 16, 487-514) suggested that Samba represents late-stage impregnation of copper mineralization into the basement, and that it was one of the youngest copper deposits known in the Central African Copperbelt. If the Samba deposit really is that young, then it would have post-dated regional deformation and metamorphism (560-510 Ma), and it ought to be undeformed and unmetamorphosed. The Samba mineralization consists of chalcopyrite and bornite, occurring as disseminations, stringers and veinlets, found in a zone >1 km along strike, in steeply-dipping lenses up to 10m thick and >150m deep. Our new major and trace element XRF geochemical data (14 samples) show that the host rocks are mainly calc-alkaline metadacites. Cu is correlated with Ag (Cu/Ag ~10,000:1) with no Au or Mo. Our study focused on the microtextures and petrology of the Samba ores. We confirm that there is alteration of similar style to that accompanying classical porphyry Cu mineralization

  13. Preliminary mineralogical data on epithermal ore veins associated with Rosia Poieni porphyry copper deposit, Apuseni Mountains, Romania

    NASA Astrophysics Data System (ADS)

    Iatan, E. L.; Popescu, Gh. C.

    2012-04-01

    Rosia Poieni is the largest porphyry copper (±Au±Mo) deposits associated with Neogene magmatic rocks from the South Apuseni Mountains, being located approximately 8 km northeast of the town of Abrud. During a recent examination of some epithermal mineralized veins, crosscutting the porphyry mineralization from the Roşia Poieni deposit, two species of tellurides and one tellurosulfide minerals were identified. The studied samples were collected from the + 1045 m level, SW side of the open pit and are represented by epithermal veins, crosscutting the porphyry copper mineralized body. The thickness of the veins is almost 4 cm. Following reflected-polarized light microscopy to identify the ore-mineral assemblages, the polished sections were studied with a Scanning Electron Microscope (SEM) equipped with a back-scattered electron (BSE) detector to study fine-sized minerals. Quantitative compositional data were determined using a Cameca SX 50 electron microprobe (EMP). Based on optical microscopy, SEM and EMPA three mineral associations have been separated inside the epithermal vein, from the margins to the centre: 1. quartz+tennantite-tetrahedrite+goldfieldite+pyrite+sphalerite; 2. quartz+pyrite+tellurobismutite; 3. chalcopyrite+hessite+vivianite. Goldfieldite occurs in anhedral grains and it is associated with tennantite-tetrahedrite and quartz. The electron microprobe analysis gave a variable content in Te between 13.28-13.39 wt.%, 43.34 wt.% Cu, 0.1 wt. % Fe, 0.2 wt.% Zn, 14.68 wt.% As, 4.35 wt.% Sb and 24.84 wt.% S. The calculated formula for the goldfieldite is Cu11.8Te1.8(Sb,As)4S13.4. The EPM analyses on tetrahedrite-tennantite revealed a low content in Te (0.02-0.03 wt.%) and 42.23 wt.% Cu, 2.67 wt.% Fe, 7.34 wt.% Zn, 0.04 wt.% Sb, 19.28 wt.% As and 28.4 wt.% S. The calculated formula is Cu9.8(Fe,Zn)2.4(Sb,As,Te)3.8S13. The variable ratio of the Te content may reflect a variable content of Te in the hydrothermal fluids from which the tellurian tetrahedrite

  14. The Jebel Ohier deposit—a newly discovered porphyry copper-gold system in the Neoproterozoic Arabian-Nubian Shield, Red Sea Hills, NE Sudan

    NASA Astrophysics Data System (ADS)

    Bierlein, F. P.; McKeag, S.; Reynolds, N.; Bargmann, C. J.; Bullen, W.; Murphy, F. C.; Al-Athbah, H.; Brauhart, C.; Potma, W.; Meffre, S.; McKnight, S.

    2016-08-01

    Ongoing exploration in the Red Sea Hills of NE Sudan has led to the identification of a large alteration-mineralization system within a relatively undeformed Neoproterozoic intrusive-extrusive succession centered on Jebel Ohier. The style of mineralization, presence of an extensive stockwork vein network within a zoned potassic-propylitic-argillic-advanced argillic-altered system, a mineralization assemblage comprising magnetite-pyrite-chalcopyrite-bornite (±gold, silver and tellurides), and the recurrence of fertile mafic to intermediate magmatism in a developing convergent plate setting all point to a porphyry copper-gold association, analogous to major porphyry Cu-Au-Mo deposits in Phanerozoic supra-subduction settings such as the SW Pacific. Preliminary U-Pb age dating yielded a maximum constraint of c. 730 Ma for the emplacement of the stockwork system into a significantly older ( c. 800 Ma) volcanic edifice. The mineralization formed prior to regional deformation and accretion of the host terrane to a stable continental margin at by c. 700 Ma, thus ensuring preservation of the deposit. The Jebel Ohier deposit is interpreted as a relatively well-preserved, rare example of a Neoproterozoic porphyry Cu-Au system and the first porphyry Cu-Au deposit to be identified in the Arabian-Nubian Shield.

  15. Silurian U-Pb zircon age (LA-ICP-MS) of granitoids from the Zelenodol Cu-porphyry deposit, Southern Urals

    NASA Astrophysics Data System (ADS)

    Grabezhev, A. I.; Ronkin, Yu. L.; Puchkov, V. N.; Shardakova, G. Yu.; Azovskova, O. B.; Gerdes, A.

    2016-01-01

    The Zelenodol porphyry Cu-(Au, Mo) deposit located about 65 km SSW of the city of Chelyabinsk is confined to the western part of the West Uralian Volcanogenic Megazone. The concordant U-Pb age of zircons from ore-bearing island-arc diorite porphyryis 418.3 Â ± 2.9 Ma.

  16. Porphyry copper assessment of East and Southeast Asia: Philippines, Taiwan (Republic of China), Republic of Korea (South Korea), and Japan: Chapter P in Global mineral resource assessment

    USGS Publications Warehouse

    Hammarstrom, Jane M.; Bookstrom, Arthur A.; Demarr, Michael W.; Dicken, Connie L.; Ludington, Stephen; Robinson,, Gilpin R.; Zientek, Michael L.

    2014-01-01

    Descriptions of the geologic basis for delineating each tract, the data used, the geologic criteria and rationale for the assessment, and results of the assessment are included in appendixes along with the description of a geographic information system (GIS) that includes tract boundaries, known porphyry copper deposits and significant prospects, and assessment results.

  17. Early Paleozoic magmatism and metallogeny in Northeast China: a record from the Tongshan porphyry Cu deposit

    NASA Astrophysics Data System (ADS)

    Hu, Xinlu; Yao, Shuzhen; Ding, Zhenju; He, Mouchun

    2017-01-01

    The Tongshan Cu deposit is located in the northern segment of the Great Xing'an Range and represents one of the few early Paleozoic porphyry Cu deposits in northeastern China. The granitic rocks in the Tongshan Cu deposit include concealed granodiorite and exposed tonalite, which yield LA-ICP-MS zircon U-Pb ages of 478 ± 3 Ma and 214 ± 3 Ma, respectively. The granodiorite has relatively high SiO2 (60.5-63.5 wt%) and Sr (596-786 ppm) contents, low Yb (1.21-1.53 ppm) and Y (9.81-13.0 ppm) contents, and initial 87Sr/86Sr ratios (0.7038-0.7040), suggesting adakitic affinity. Combined with its positive ɛNd( t) values (3.5-5.4), low Mg# values (41-50), and low contents of Cr (18.6-29.0 ppm) and Ni (7.3-9.1 ppm), we propose an origin by partial melting of a juvenile mafic lower crust in a post-collisional setting after the amalgamation of the Erguna and Xing'an Blocks. The tonalite is characterized by high SiO2 (63.1-65.9 wt%) and Al2O3 (16.0-16.3 wt%) contents, low (87Sr/86Sr) i ratios (0.7041-0.7042), positive ɛNd( t) values (2.6-3.0), along with LILE and LREE enrichments and Nb-Ta-Ti depletions, suggesting an origin by partial melting of juvenile mafic lower crust, coupled with fractional crystallization, in a post-orogenic setting after the collision between the Xing'an and Songnen Blocks. The δD values of ore-forming fluids range from -100 to -93 ‰, and the δ18O values calculated from hydrothermal quartz are between -3 and 10 ‰. The δ34S values of sulfides vary from -2.6 to -1.1 ‰. Field observations, as well as the geochronological and H-O-S isotopic data, suggest that the Cu mineralization at Tongshan was genetically linked with the granodiorite.

  18. The Sweet Home rhodochrosite specimen mine, Alma District, Central Colorado: the porphyry molybdenum-fluorine connection

    NASA Astrophysics Data System (ADS)

    Bartos, Paul J.; Nelson, Eric P.; Misantoni, Dean

    2007-02-01

    Intermediate sulfidation veins containing quartz-sphalerite-tetrahedrite-rhodochrosite-fluorite in the Sweet Home Mine, Alma District, Colorado were originally mined for silver starting in 1873. For the last 13 years up until 2004, however, the mine has produced world-class rhodochrosite specimens. Some of these specimens are considered to be among the finest mineral specimens ever produced and the finest of their species with values well over 1 million US dollars. The extraction, preparation, and marketing techniques pioneered at the Sweet Home operation have revolutionized the minerals specimen industry. The Sweet Home deposit is interpreted as a single pulse variant of a Climax-type hydrothermal system. Evidence for this includes (1) an age of mineralization (25.8 ± 0.3 Ma) that coincides with the age of the end stages of mineralization of the Climax molybdenum deposit approximately 7.5 km to the northeast; (2) a geochemical (Mn, W, F) and mineralogical (topaz, fluorite, hubnerite, greisen muscovite) signature typically associated with Climax-type systems; (3) the presence of porphyry rhyolite dikes, a breccia dike, and local quartz-molybdenite veins in the nearby area; (4) a small pegmatite within the mine with an age (25.9 ± 0.3 Ma) coincident with mineralization, which also contains minor amounts of disseminated molybdenite; and (5) the presence of similar-appearing gemmy, red rhodochrosites at Climax and other high-silica rhyolite systems. A significant difference is that unlike Climax-type systems, the Sweet Home hydrothermal system appears to have consisted of a single, relatively small pulse of magmatic fluid that slowly cooled and diluted with groundwater. This is inferred to have occurred at moderate depths in the order of 1.5-2.5 km below the surface. The fluids that formed the Sweet Home veins were dilute (salinity in the order of 2-4 wt% NaCl equivalent), high-temperature (temperatures of homogenization up to 370°C), and initially of magmatic

  19. Quantitative Mineral Resource Assessment of Copper, Molybdenum, Gold, and Silver in Undiscovered Porphyry Copper Deposits in the Andes Mountains of South America

    USGS Publications Warehouse

    Cunningham, Charles G.; Zappettini, Eduardo O.; Vivallo S., Waldo; Celada, Carlos Mario; Quispe, Jorge; Singer, Donald A.; Briskey, Joseph A.; Sutphin, David M.; Gajardo M., Mariano; Diaz, Alejandro; Portigliati, Carlos; Berger, Vladimir I.; Carrasco, Rodrigo; Schulz, Klaus J.

    2008-01-01

    Quantitative information on the general locations and amounts of undiscovered porphyry copper resources of the world is important to exploration managers, land-use and environmental planners, economists, and policy makers. This publication contains the results of probabilistic estimates of the amounts of copper (Cu), molybdenum (Mo), gold (Au), and silver (Ag) in undiscovered porphyry copper deposits in the Andes Mountains of South America. The methodology used to make these estimates is called the 'Three-Part Form'. It was developed to explicitly express estimates of undiscovered resources and associated uncertainty in a form that allows economic analysis and is useful to decisionmakers. The three-part form of assessment includes: (1) delineation of tracts of land where the geology is permissive for porphyry copper deposits to form; (2) selection of grade and tonnage models appropriate for estimating grades and tonnages of the undiscovered porphyry copper deposits in each tract; and (3) estimation of the number of undiscovered porphyry copper deposits in each tract consistent with the grade and tonnage model. A Monte Carlo simulation computer program (EMINERS) was used to combine the probability distributions of the estimated number of undiscovered deposits, the grades, and the tonnages of the selected model to obtain the probability distributions for undiscovered metals in each tract. These distributions of grades and tonnages then can be used to conduct economic evaluations of undiscovered resources in a format usable by decisionmakers. Economic evaluations are not part of this report. The results of this assessment are presented in two principal parts. The first part identifies 26 regional tracts of land where the geology is permissive for the occurrence of undiscovered porphyry copper deposits of Phanerozoic age to a depth of 1 km below the Earth's surface. These tracts are believed to contain most of South America's undiscovered resources of copper. The

  20. Tectonic setting of the pebble and other copper-gold-molybdenum porphyry deposits within the evolving middle cretaceous continental margin of Northwestern North America

    USGS Publications Warehouse

    Goldfarb, Richard J.; Anderson, Eric; Hart, Craig J.R.

    2013-01-01

    The Pebble Cu-Au-Mo deposit in southwestern Alaska, containing the largest gold resource of any known porphyry in the world, developed in a tectonic setting significantly different from that of the present-day. It is one of a series of metalliferous middle Cretaceous porphyritic granodiorite, quartz monzonite, and diorite bodies, evolved from lower crust and metasomatized lithospheric mantle melts, which formed along much of the length of the North American craton suture with the Peninsular-Alexander-Wrangellia arc. The porphyry deposits were emplaced within the northernmost two of a series of ca. 130 to 80 Ma flysch basins that define the suture, as well as into arc rocks immediately seaward of the two basins. Deposits include the ca. 100 to 90 Ma Pebble, Neacola, and other porphyry prospects along the Kahiltna basin-Peninsula terrane boundary, and the ca. 115 to 105 Ma Baultoff, Carl Creek, Horsfeld, Orange Hill, Bond Creek, and Chisna porphyries along the Nutzotin basin-Wrangellia terrane boundary.The porphyry deposits probably formed along the craton margin more than 1,000 km to the south of their present latitude. Palinspastic reconstructions of plate kinematics from this period are particularly difficult because magmatism overlaps the 119 to 83 Ma Cretaceous Normal Superchron, a period when sea-floor magnetic data are lacking. Our favored scenario is that ore formation broadly overlaps the cessation of sedimentation and contraction and the transition to a transpressional continental margin regime, such that the remnant ocean basins were converted to strike-slip basins. The basins and outboard Peninsular-Alexander-Wrangellia composite superterrane, which are all located seaward of the deep crustal Denali-Farewell fault system, were subjected to northerly dextral transpression for as long as perhaps 50 m.y., beginning at ca. 95 ± 10 Ma. The onset of this transpression was marked by development of the mineralized bodies along fault segments on the seaward side

  1. Petrogenesis of Paleocene-Eocene porphyry deposit-related granitic rocks in the Yaguila-Sharang ore district, central Lhasa terrane, Tibet

    NASA Astrophysics Data System (ADS)

    Zhao, Junxing; Li, Guangming; Evans, Noreen J.; Qin, Kezhang; Li, Jinxiang; Zhang, Xia'nan

    2016-11-01

    The Paleocene-Eocene ore deposits in the Gangdese Metallogenic Belt, Tibet, are thought to have been formed during the main period of India-Asia continental collision. This paper reports the whole-rock major element, trace element, and Sr-Nd-Hf isotopic compositions and zircon trace element contents of volcanic and intrusive rocks from the Paleocene Yaguila skarn Pb-Zn-Ag deposit and adjacent Eocene Sharang porphyry Mo deposit in the central Lhasa terrane, Tibet. Geochemical signatures and Nd-Hf isotopic compositions indicate that the Yaguila Cretaceous rhyolitic rocks were formed by the melting of ancient continental crust, whereas the Paleocene causative granite porphyry may have resulted from the interaction between mantle-derived and crustal-derived materials when continental collision was initiated. The dramatic increase of εNd(t) values between emplacement of the granite porphyry and later porphyritic biotite granite suggests a greater involvement of mantle materials during the crystallization of the barren biotite granite stock. The post-ore Miocene granodiorite porphyry has a similar geochemical signature to the Sharang Miocene dykes, suggesting they were both generated from melting of enriched lithospheric mantle. Nd-Hf mixing calculations indicate an increasing contribution of mantle materials in Paleocene to Eocene intrusions, consistent with the regional tectonic model of Neo-Tethyan oceanic slab roll-back and break-off. Zircons from both the Yaguila and Sharang ore-related porphyries have higher Ce anomalies than those from the barren granitoids, suggesting that Mo mineralization was closely related to highly oxidized and differentiated magma. The fertile intrusions in the Yaguila-Sharang district contain EuN/EuN∗ values from 0.3 to 0.6, higher than the non-mineralized intrusions. The processes of early crystallization of plagioclase and/or SO2-degassing from underlying magma can explain the observed negative Eu anomalies in zircon.

  2. Geological analysis of aeromagnetic data from southwestern Alaska: implications for exploration in the area of the Pebble porphyry Cu-Au-Mo deposit

    USGS Publications Warehouse

    Anderson, Eric D.; Hitzman, Murray W.; Monecke, Thomas; Bedrosian, Paul A.; Shah, Anjana K.; Kelley, Karen D.

    2013-01-01

    Aeromagnetic data are used to better understand the geology and mineral resources near the Late Cretaceous Pebble porphyry Cu-Au-Mo deposit in southwestern Alaska. The reduced-to-pole (RTP) transformation of regional-scale aeromagnetic data shows that the Pebble deposit is within a cluster of magnetic anomaly highs. Similar to Pebble, the Iliamna, Kijik, and Neacola porphyry copper occurrences are in magnetic highs that trend northeast along the crustal-scale Lake Clark fault. A high-amplitude, short- to moderate-wavelength anomaly is centered over the Kemuk occurrence, an Alaska-type ultramafic complex. Similar anomalies are found west and north of Kemuk. A moderate-amplitude, moderate-wavelength magnetic low surrounded by a moderate-amplitude, short-wavelength magnetic high is associated with the gold-bearing Shotgun intrusive complex. The RTP transformation of the district-scale aeromagnetic data acquired over Pebble permits differentiation of a variety of Jurassic to Tertiary magmatic rock suites. Jurassic-Cretaceous basalt and gabbro units and Late Cretaceous biotite pyroxenite and granodiorite rocks produce magnetic highs. Tertiary basalt units also produce magnetic highs, but appear to be volumetrically minor. Eocene monzonite units have associated magnetic lows. The RTP data do not suggest a magnetite-rich hydrothermal system at the Pebble deposit. The 10-km upward continuation transformation of the regional-scale data shows a linear northeast trend of magnetic anomaly highs. These anomalies are spatially correlated with Late Cretaceous igneous rocks and in the Pebble district are centered over the granodiorite rocks genetically related to porphyry copper systems. The spacing of these anomalies is similar to patterns shown by the numerous porphyry copper deposits in northern Chile. These anomalies are interpreted to reflect a Late Cretaceous magmatic arc that is favorable for additional discoveries of Late Cretaceous porphyry copper systems in southwestern

  3. Petrogenesis of Late Jurassic granodiorites from Gutian, Fujian Province, South China: Implications for multiple magma sources and origin of porphyry Cu-Mo mineralization

    NASA Astrophysics Data System (ADS)

    Li, Bin; Jiang, Shao-Yong; Lu, An-Huai; Lai, Jian-Qing; Zhao, Kui-Dong; Yang, Tao

    2016-11-01

    The Gutian porphyry Cu-Mo deposit is a newly proved porphyry copper deposit in the coastal South China associated with granodioritic porphyries. In this study, zircon U-Pb ages and Hf isotope data, as well as geochemical and Sr-Nd-Pb-Re-Os isotopic compositions, are reported for these intrusions and minerals. Both zircon U-Pb and molybdenite Re-Os dating suggest that the Gutian granodiorite porphyries and related mineralization formed at 160 Ma. The Gutian granodiorites show a low-Mg adakitic geochemical affinity, with relatively high K2O but low Cr and Ni contents. These rocks have initial (87Sr/86Sr)i ratios of 0.7085 to 0.7097, negative εNd(t) values (- 12.5 to - 7.8), (206Pb/204Pb)t ratios of 18.048 to 18.241, (207Pb/204Pb)t ratios of 15.609 to 15.628, and (208Pb/204Pb)t ratios of 38.494 to 38.667. Zircons from the granodiorites have negative εHf(t) values of - 15.7 to - 8.5, which are close to those of Cathaysia crust-derived melts. Geochemical and Sr-Nd-Pb-Hf isotopic compositions suggest that they may be derived from Late Jurassic thickened juvenile lower crust. These lower crustal magma sources may not only contain pre-Proterozoic basement rocks, but also involve Triassic and Middle-Late Jurassic arc magmas within the lower crust, which were likely derived from an enriched mantle source associated with paleo-Pacific Plate subduction from the Middle to Late Jurassic. The Gutian ore-related granodiorites represent a new example for significant contributions of ancient subduction melts and enriched mantle-derived sources for porphyry-type magmatism and Cu-Mo mineralization, which occurred in response to an arc regime during the Middle to Late Jurassic in South China. Supplemental Table S2. Hf isotopic compositions of zircons from the studied rocks from the Gutian porphyry deposit in South China. Supplemental Table S3. Statistics for zircon U-Pb ages and Hf isotope compositions from Gutian granodiorites in South China Supplemental Table S4. Major element (wt

  4. Timing of porphyry (Cu-Mo) and base metal (Zn-Pb-Ag-Cu) mineralisation in a magmatic-hydrothermal system—Morococha district, Peru

    NASA Astrophysics Data System (ADS)

    Catchpole, Honza; Kouzmanov, Kalin; Bendezú, Aldo; Ovtcharova, Maria; Spikings, Richard; Stein, Holly; Fontboté, Lluís

    2015-12-01

    The Morococha district in central Peru is characterised by economically important Cordilleran polymetallic (Zn-Pb-Ag-Cu) vein and replacement bodies and the large Toromocho porphyry Cu-Mo deposit in its centre. U-Pb, Re-Os, and 40Ar/39Ar geochronology data for various porphyry-related hydrothermal mineralisation styles record a 3.5-Ma multi-stage history of magmatic-hydrothermal activity in the district. In the late Miocene, three individual magmatic-hydrothermal centres were active: the Codiciada, Toromocho, and Ticlio centres, each separated in time and space. The Codiciada centre is the oldest magmatic-hydrothermal system in the district and consists of a composite porphyry stock associated with anhydrous skarn and quartz-molybdenite veins. The hydrothermal events are recorded by a titanite U-Pb age at 9.3 ± 0.2 Ma and a molybdenite Re-Os age at 9.26 ± 0.03 Ma. These ages are indistinguishable from zircon U-Pb ages for porphyry intrusions of the composite stock and indicate a time span of 0.2 Ma for magmatic-hydrothermal activity. The small Ticlio magmatic-hydrothermal centre in the west of the district has a maximum duration of 0.3 Ma, ranging from porphyry emplacement to porphyry mineralisation at 8.04 ± 0.14 Ma (40Ar/39Ar muscovite cooling age). The Toromocho magmatic-hydrothermal centre has a minimum of five recorded porphyry intrusions that span a total of 1.3 Ma and is responsible for the formation of the giant Toromocho Cu-Mo deposit. At least two hydrothermal pulses are identified. Post-dating a first pulse of molybdenite mineralisation, wide-spread hydrous skarn covers an area of over 6 km2 and is recorded by five 40Ar/39Ar cooling ages at 7.2-6.8 Ma. These ages mark the end of the slowly cooling and long-lived Toromocho magmatic-hydrothermal centre soon after last magmatic activity at 7.26 ± 0.02 Ma. District-wide (50 km2) Cordilleran base metal vein and replacement bodies post-date the youngest recorded porphyry mineralisation event at Toromocho

  5. Hydrothermal Evolution of the Giant Cenozoic Kadjaran porphyry Cu-Mo deposit, Tethyan metallogenic belt, Armenia, Lesser Caucasus: mineral paragenetic, cathodoluminescence and fluid inclusion constraints

    NASA Astrophysics Data System (ADS)

    Hovakimyan, Samvel; Moritz, Robert; Tayan, Rodrik; Rezeau, Hervé

    2016-04-01

    The Lesser Caucasus belongs to the Central segment of the Tethyan metallogenic belt and it is a key area to understand the metallogenic evolution between the Western & Central parts of the Tethyan belt and its extension into Iran. Zangezur is the most important mineral district in the southernmost Lesser Caucasus. It is a component of the South Armenian block, and it was generated during the convergence and collision of the southern margin of the Eurasian plate and the northern margin of the Arabian plate, and terranes of Gondwana origin (Moritz et al., in press). The Zangezur ore district consists of the Tertiary Meghri-Ordubad composite pluton, which is characterized by a long-lasting Eocene to Pliocene magmatic, tectonic and metallogenic evolution. It hosts major porphyries Cu-Mo and epithermal Au - polymetallic deposits and occurrences, including the giant world class Kadjaran porphyry Cu-Mo deposit (2244 Mt reserves, 0.3% Cu, 0.05% Mo and 0.02 g/t Au). The Kadjaran deposit is hosted by a monzonite intrusion (31.83±0.02Ma; Moritz et al., in press). Detailed field studies of the porphyry stockwork and veins of the different mineralization stages, their crosscutting and displacement relationships and the age relationship between different paragenetic mineral associations were the criteria for distinction of the main stages of porphyry mineralization at the Kadjaran deposit. The economic stages being: quartz- molybdenite, quartz-molybdenite-chalcopyrite, and quartz-chalcopyrite. The main paragenetic association of the Kadjaran porphyry deposit includes pyrite, molybdenite, chalcopyrite, bornite, chalcocite, pyrrhotite, covellite, sphalerite, and galena. Recent field observations in the Kadjaran open pit revealed the presence of epithermal veins with late vuggy silica and advanced argillic alteration in the north-eastern and eastern parts of the deposit. They are distributed as separate veins and have also been recognized in re-opened porphyry veins and in

  6. USGS exploration geochemistry studies at the Pebble porphyry Cu-Au-Mo deposit, Alaska-pdf of presentation

    USGS Publications Warehouse

    Eppinger, Robert G.; Kelley, Karen D.; Fey, David L.; Giles, Stuart A.; Minsley, Burke J.; Smith, Steven M.

    2010-01-01

    From 2007 through 2010, scientists in the U.S. Geological Survey (USGS) have been conducting exploration-oriented geochemical and geophysical studies in the region surrounding the giant Pebble porphyry Cu-Au-Mo deposit in southwestern Alaska. The Cretaceous Pebble deposit is concealed under tundra, glacial till, and Tertiary cover rocks, and is undisturbed except for numerous exploration drill holes. These USGS studies are part of a nation-wide research project on evaluating and detecting concealed mineral resources. This report focuses on exploration geochemistry and comprises illustrations and associated notes that were presented as a case study in a workshop on this topic. The workshop, organized by L.G. Closs and R. Glanzman, is called 'Geochemistry in Mineral Exploration and Development,' presented by the Society of Economic Geologists at a technical conference entitled 'The Challenge of Finding New Mineral Resources: Global Metallogeny, Integrative Exploration and New Discoveries,' held at Keystone, Colorado, October 2-5, 2010.

  7. Geology and reconnaissance stable isotope study of the Oyu Tolgoi porphyry Cu-Au system, South Gobi, Mongolia

    USGS Publications Warehouse

    Khashgerel, B.-E.; Rye, R.O.; Hedenquist, J.W.; Kavalieris, I.

    2006-01-01

    The Oyu Tolgoi porphyry Cu-Au system in the South Gobi desert, Mongolia, comprises five deposits that extend over 6 km in a north-northeast-oriented zone. They occur in a middle to late Paleozoic are terrane and are related to Late Devonian quartz monzodiorite intrusions. The Hugo Dummett deposits are the northernmost and deepest, with up to 1,000 m of premineral sedimentary and volcanic cover rock remaining. They are the largest deposits discovered to date and characterized by high-grade copper (>2.5% Cu) and gold (0.5-2 g/t) mineralization associated with intense quartz veining and several phases of quartz monzodiorite intruded into basaltic volcanic host rocks. Sulfide minerals in these deposits are zoned outward from a bornite-dominated core to chalcopyrite, upward to pyrite ?? enargite and covellite at shallower depth. The latter high-sulfidation-state sulfides are hosted by advanced argillic alteration mineral associations. This alteration is restricted mainly to dacitic ash-flow tuff that overlies the basaltic volcanic rock and includes ubiquitous quartz and pyrophyllite, kaolinite, plus late dickite veins, as well as K alunite, Al phosphate-sulfate minerals, zunyite, diaspore, topaz, corundum, and andalusite. A reconnaissance oxygen-hydrogen and sulfur isotope study was undertaken to investigate the origin of several characteristic alteration minerals in the Oyu Tolgoi system, with particular emphasis on the Hugo Dummett deposits. Based on the isotopic composition of O, H, and S (??18O(SO4) = 8.8-20.1???, ??D = -73 to -43???, ??34S = 9.8-17.9???), the alunite formed from condensation of magmatic vapor that ascended to the upper parts of the porphyry hydrothermal system, without involvement of significant amounts of meteoric water. The isotopic data indicate that pyrophyllite (??18O = 6.5-10.9???, ??D = -90 to -106???) formed from a magmatic fluid with a component of meteoric water. Muscovite associated with quartz monzodiorite intrusions occurs in the core

  8. Hydrothermal alteration and mass exchange in the hornblende latite porphyry, Rico, Colorado

    USGS Publications Warehouse

    Larson, P.B.; Cunningham, C.G.; Naeser, C.W.

    1994-01-01

    The Rico paleothermal anomaly, southwestern Colorado, records the effects of a large hydrothermal system that was active at 4 Ma. This hydrothermal system produced the deep Silver Creek stockwork Mo deposit, which formed above the anomaly's heat source, and shallower base and precious-metal vein and replacement deposits. A 65 Ma hornblende latite porphyry is present as widespread sills throughout the area and provided a homogenous material that recorded the effects of the hydrothermal system up to 8 km from the center. Hydrothermal alteration in the latite can be divided into a proximal facies which consists of two assemblages, quartz-illite-calcite and chlorite-epidote, and a distal facies which consists of a distinct propylitic assemblage. Temperatures were gradational vertically and laterally in the anomaly, and decreased away from the centra heat source. A convective hydrothermal plume, 3 km wide and at least 2 km high, was present above the stock-work molybdenum deposit and consisted of upwelling, high-temperature fluids that produced the proximal alteration facies. Distal facies alteration was produced by shallower cooler fluids. The most important shallow base and precious-metal vein deposits in the Rico district are at or close to the boundary of the thermal plume. Latite within the plume had a large loss of Na2O, large addition of CaO, and variable SiO2 exchante. Distal propylitized latite samples lost small amounts of Na2O and CaO and exchanged minor variable amounts of SiO2. The edge of the plume is marked by steep Na2O exchange gradients. Na2O exchange throughout the paleothermal anomaly was controlled by the reaction of the albite components in primary plagioclase and alkali feldspars. Initial feldspar alteration in the distal facies was dominated by reaction of the plagioclase, and the initial molar ratio of reactants (alkali feldspar albite component to plagioclase albite component) was 0.35. This ratio of the moles of plagioclase to alkali feldspar

  9. Devonian and carboniferous arcs of the oyu tolgoi porphyry Cu-Au district, South Gobi region, Mongolia

    USGS Publications Warehouse

    Wainwright, A.J.; Tosdal, R.M.; Forster, C.N.; Kirwin, D.J.; Lewis, P.D.; Wooden, J.L.

    2011-01-01

    The Central Asian orogenic belt consists of microcontinental blocks and mobile belts positioned between the Siberian craton and the Tarim and North China cratons. Extending across Asia for 5000 km, the belt consists of terranes that decrease in age southward away from the Siberian craton. A time-stratigraphic-structural sequence for the rocks is critical to defining the tectonic evolution of the belt. In the Oyu Tolgoi area of the South Gobi Desert (Mongolia), Devonian and Carboniferous rocks record the construction of multiple arcs, formation of a giant porphyry Cu-Au system, exhumation, and polyphase deformation. The oldest rocks are basaltic volcanic and subvolcanic rocks of the Devonian Alagbayan Group intruded by Late Devonian quartz monzodiorite stocks and dikes, which host giant porphyry Cu-Au deposits. The rocks were exhumed, overlain by pyroclastic rocks, and then tectonically buried by marine mafic supracrustal rocks prior to the youngest Devonian granodiorite intrusions. The postmineral Carboniferous Gurvankharaat Group unconformably overlying the deformed terrane consists of effusive, pyroclastic, subvolcanic and volcaniclastic rocks, as well as sedimentary units. The supracrustal rocks underwent polyphase shortening after 330 Ma and prior to 290 Ma. Variations in stratigraphic sequences suggest that the region is underlain by a submarine arc that became emergent during the Upper Devonian and remained subaerial to shallow subaqueous through much of the Carboniferous. Xenocrystic zircons in igneous rocks suggest that the offshore arcs were sufficiently close to ancient crust to have interacted with detritus shed into marine basins, most likely from the Siberian craton and fringing early Paleozoic terranes. ?? 2011 Geological Society of America.

  10. Sr-Nd-Pb-Hf isotope systematics of the Hugo Dummett Cu-Au porphyry deposit (Oyu Tolgoi, Mongolia)

    NASA Astrophysics Data System (ADS)

    Dolgopolova, A.; Seltmann, R.; Armstrong, R.; Belousova, E.; Pankhurst, R. J.; Kavalieris, I.

    2013-04-01

    Major and trace element geochemistry including Sr-Nd-Pb-Hf isotopic data are presented for a representative sample suite of Late Devonian to Early Carboniferous plutonic and volcanic rocks from the Hugo Dummett deposit of the giant Oyu Tolgoi porphyry Cu-Au district in South Gobi, Mongolia. Sr and Nd isotopes (whole-rock) show restricted ranges of initial compositions, with positive ɛNdt mainly between + 3.4 and + 7.4 and (87Sr/86Sr)t predominantly between 0.7037 and 0.7045 reflecting magma generation from a relatively uniform juvenile lithophile-element depleted source. Previously dated zircons from the plutonic rocks exhibit a sample-averaged range of ɛHft values of + 11.6 to + 14.5. Depleted-mantle model ages of 420-830 (Nd) and 320-730 Ma (zircon Hf) limit the involvement of pre-Neoproterozoic crust in the petrogenesis of the intermediate to felsic calc-alkaline magmas to, at most, a minor role. Pb isotopes (whole-rock) show a narrow range of unradiogenic initial compositions: 206Pb/204Pb 17.40-17.94, 207Pb/204Pb 15.43-15.49 and 208Pb/204Pb 37.25-37.64, in agreement with Sr-Nd-Hf isotopes indicating the dominance of a mantle component. All four isotopic systems suggest that the magmas from which the large Oyu Tolgoi porphyry system was generated originated predominantly from juvenile material within the subduction-related setting of the Gurvansayhan terrane.

  11. The discovery and geophysical response of the Atlántida Cu-Au porphyry deposit, Chile

    NASA Astrophysics Data System (ADS)

    Hope, Matthew; Andersson, Steve

    2016-03-01

    The discovery of the Atlántida Cu-Au-Mo porphyry deposit, which is unconformably overlain by 25-80 m of gravels, is a recent example of exploration success under cover in a traditional mining jurisdiction. Early acquisition of geophysics was a key tool in the discovery, and in later guiding further exploration drilling throughout the life of the project. Detailed review of the geophysical response of the deposit, with respect to the distribution of lithologies and alteration, coupled with their petrophysical properties has allowed full characterisation, despite no exposure at the surface of host rock nor porphyry-style mineralisation. Data acquired over the project include induced polarisation, magnetotellurics, ground and airborne magnetics, ground-based gravimetry, and petrophysical sampling. The distribution of the key geological features of the deposit has been inferred via acquisition of petrophysical properties and interpretation of surface geophysical datasets. Magnetic susceptibility is influenced strongly by both alteration and primary lithology, whilst density variations are dominated by primary lithological control. Several studies have shown that electrical properties may map the footprint of the hydrothermal system and associated mineralisation, via a combination of chargeability and resistivity. These properties are observed in geophysical datasets acquired at surface and allow further targeting and sterilisation at the deposit and project scale. By understanding these geophysical characteristics in a geological context, these data can be used to infer distribution of lithological units, depth to exploration targets and the potential for high grade mineralisation. Future exploration will likely be increasingly reliant on the understanding of the surface manifestations of buried deposits in remotely acquired data. This review summarises the application and results of these principles at the Atlántida project of northern Chile. Geophysical data can be

  12. New thermochronologic constraints on the evolution of the Zaldívar porphyry copper deposit, Northern Chile

    NASA Astrophysics Data System (ADS)

    Campos, Eduardo; Wijbrans, Jan; Andriessen, Paul A. M.

    2009-04-01

    Life spans and thermal evolution of hydrothermal systems are of fundamental metallogenic importance. We were able to establish the chronology and cooling history of the Zaldívar porphyry copper deposit (Northern Chile) by applying a combination of different isotopic dating methods in minerals with different closure temperatures, including 40Ar/39Ar geochronology and zircon fission track thermochronology, together with fluid inclusion thermometry and previous published U-Pb zircon geochronology. The hydrothermal mineralization in the Zaldívar deposit is genetically related to the Llamo Porphyry unit. Samples of igneous biotites from this intrusion yielded 40Ar/39Ar plateau ages between 35.5 ± 0.7 and 37.7 ± 0.4 Ma defining a weighted average of 36.6 ± 0.5 Ma (2 σ). In contrast, one sample from the Zaldívar porphyry, one from the andesites, and two from the Llamo porphyry yielded considerably younger fission track ages of approximately 29 Ma with a weighted mean for all ages of 29.1 ± 1.7 Ma (2 σ). Thermal and compositional constraints for the hydrothermal system in the Zaldívar deposit from fluid inclusions thermometry show that at least three fluid types broadly characterize two main hydrothermal episodes during the evolution of the deposit. The main mineralization and alteration event is characterized by high temperature (above 320°C) hypersaline fluids (salinity between 30 and 56 wt.% NaCl equivalents) coexisting with low-density gas-rich inclusions (salinity less than 17 wt.% NaCl equivalents) that homogenizing into the gas phase at temperatures above 350°C. The second episode corresponds to a low-temperature event which is characterized by liquid-rich fluid inclusions that homogenize into the liquid phase at temperatures ranging from 200°C to 300°C with salinities lower than 10 wt.% NaCl equivalents. The 40Ar/39Ar data (36.6 ± 0.5 Ma, weighted average) obtained from igneous biotites represent the minimum age for the last high-temperature (above

  13. U-Pb (zircon) and geochemical constraints on the age, origin, and evolution of Paleozoic arc magmas in the Oyu Tolgoi porphyry Cu-Au district, southern Mongolia

    USGS Publications Warehouse

    Wainwright, A.J.; Tosdal, R.M.; Wooden, J.L.; Mazdab, F.K.; Friedman, R.M.

    2011-01-01

    Uranium-Pb (zircon) ages are linked with geochemical data for porphyry intrusions associated with giant porphyry Cu-Au systems at Oyu Tolgoi to place those rocks within the petrochemical framework of Devonian and Carboniferous rocks of southern Mongolia. In this part of the Gurvansayhan terrane within the Central Asian Orogenic Belt, the transition from Devonian tholeiitic marine rocks to unconformably overlying Carboniferous calc-alkaline subaerial to shallow marine volcanic rocks reflects volcanic arc thickening and maturation. Radiogenic Nd and Pb isotopic compositions (??Nd(t) range from +3.1 to +7.5 and 206Pb/204Pb values for feldspars range from 17.97 to 18.72), as well as low high-field strength element (HFSE) contents of most rocks (mafic rocks typically have <1.5% TiO2) are consistent with magma derivation from depleted mantle in an intra-oceanic volcanic arc. The Late Devonian and Carboniferous felsic rocks are dominantly medium- to high-K calc-alkaline and characterized by a decrease in Sr/Y ratios through time, with the Carboniferous rocks being more felsic than those of Devonian age. Porphyry Cu-Au related intrusions were emplaced in the Late Devonian during the transition from tholeiitic to calc-alkaline arc magmatism. Uranium-Pb (zircon) geochronology indicates that the Late Devonian pre- to syn-mineral quartz monzodiorite intrusions associated with the porphyry Cu-Au deposits are ~372Ma, whereas granodiorite intrusions that post-date major shortening and are associated with less well-developed porphyry Cu-Au mineralization are ~366Ma. Trace element geochemistry of zircons in the Late Devonian intrusions associated with the porphyry Cu-Au systems contain distinct Th/U and Yb/Gd ratios, as well as Hf and Y concentrations that reflect mixing of magma of distinct compositions. These characteristics are missing in the unmineralized Carboniferous intrusions. High Sr/Y and evidence for magma mixing in syn- to late-mineral intrusions distinguish the Late

  14. Geological, geochronological, geochemical, and Sr-Nd-O-Hf isotopic constraints on origins of intrusions associated with the Baishan porphyry Mo deposit in eastern Tianshan, NW China

    NASA Astrophysics Data System (ADS)

    Wang, Yinhong; Xue, Chunji; Liu, Jiajun; Zhang, Fangfang

    2016-10-01

    The Baishan porphyry Mo deposit (0.72 Mt; 0.06 % Mo) is located in the interior of the eastern Tianshan orogenic belt in Xinjiang, NW China. The deposit comprises 15 orebodies that are associated with monzogranite and granite porphyry stocks and are structurally controlled by roughly EW-trending faults. Secondary ion mass spectrometry (SIMS) zircon U-Pb dating of the monzogranite and granite porphyry yielded the Middle Triassic age (228 ± 2 to 227 ± 2 Ma), which coincide with the molybdenite Re-Os model ages ranging from 226 ± 3 to 228 ± 3 Ma. The Triassic monzogranite and granite porphyry belong to high-K calc-alkaline series and are characterized by high SiO2 and Al2O3 and low MgO, TiO2, and P2O5 concentrations, with negative Eu anomalies (δEu = 0.55-0.91). The least-altered monzogranite and granite porphyry yield uniform ɛ Nd( t) values from +1.6 to +3.6, and wide (87Sr/86Sr) i ratios ranging between 0.7035 and 0.7071, indicating that they were derived from the lower crust. In situ O-Hf isotopic analyses on zircon using SIMS and laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) indicate that the δ18O and ɛ Hf( t) values of zircon from a monzogranite sample vary from 6.1 to 7.3 ‰ and +8.0 to +11.7, respectively, whereas zircon from a granite porphyry sample vary from 6.2 to 6.9 ‰ and +7.3 to +11.2, respectively. The geochemical and isotopic data imply that the primary magmas of the Baishan granite were likely derived from partial melts from the lower crust involving some mantle components. The Baishan Mo deposit and granitic emplacement were proposed to be most likely related to post-orogenic lithospheric extension and magmatic underplating. An extensional event coupled with the rising of hot mantle-derived melts triggered partial melting of the lower crust, as well as provided metals (Mo).

  15. Formation of the giant Chalukou porphyry Mo deposit in northern Great Xing'an Range, NE China: Partial melting of the juvenile lower crust in intra-plate extensional environment

    NASA Astrophysics Data System (ADS)

    Li, Zhen-Zhen; Qin, Ke-Zhang; Li, Guang-Ming; Ishihara, Shunso; Jin, Lu-Ying; Song, Guo-Xue; Meng, Zhao-Jun

    2014-08-01

    The Chalukou porphyry Mo deposit (2.46 Mt @ 0.087% Mo), located in the northern Great Xing'an Range, NE China, is the largest Mo deposit discovered in China so far. The host rocks consist of aplite porphyry, granite porphyry and quartz porphyry, and are intruded into Lower Ordovician intermediate-felsic volcanic-sedimentary rocks and pre-ore monzogranite and are cut by post-ore feldspar porphyry, diorite porphyry and quartz monzonite porphyry. Here, we present the zircon U-Pb ages, whole-rock geochemistry, Sr-Nd isotopic and zircon Hf isotopic data for the pre-ore, syn-ore and post-ore intrusive rocks. The Chalukou ore-forming porphyries intruded during 147-148 Ma and have high-silica, alkali-rich, metaluminous to slightly peraluminous compositions and are oxidized. They are enriched in large ion lithophile elements (e.g. K, Rb, U and Th), light REE and depleted in high-field strength elements (e.g. Nb, P and Ti). Depletions in Eu, Ba, Sr, Nb, Ta, P and Ti suggest that they have experienced strong fractional crystallization of plagioclase, biotite, hornblende and accessory minerals. The pre-ore monzogranite (~ 172 Ma) also belongs to the high-K calc-alkaline series. Highly fractionated REE patterns ((La/Yb) N = 19.6-21.7), high values of Sr/Y (54-69) and La/Yb (29-32), are adakite-like geochemical features. The post-ore rocks (~ 141-128 Ma) have similar geochemical characteristics with ore-forming porphyries except that quartz monzonite porphyry shows no Ba-Sr negative anomaly. All intrusive rocks have relative low initial 87Sr/86Sr (0.705413-0.707889) and εNd (t) values (- 1.28 to + 0.92), positive εHf (t) values (+ 2.4 to + 10.1) and young two-stage Nd and Hf model ages (TDM2 (Nd) = 863-977 Ma, TDM2 (Hf) = 552-976 Ma). These geochemical and isotopic data are interpreted to demonstrate that the ore-forming porphyries formed by partial melting of the juvenile lower crust caused by underplating of mafic magmas in an intra-plate extensional setting. The pre

  16. Regional mapping of hydrothermally altered igneous rocks along the Urumieh-Dokhtar, Chagai, and Alborz Belts of western Asia using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and Interactive Data Language (IDL) logical operators: a tool for porphyry copper exploration and assessment: Chapter O in Global mineral resource assessment

    USGS Publications Warehouse

    Mars, John L.; Zientek, M.L.; Hammarstrom, J.M.; Johnson, K.M.; Pierce, F.W.

    2014-01-01

    The ASTER alteration map and corresponding geologic maps were used to select circular to elliptical patterns of argillic- and phyllic-altered volcanic and intrusive rocks as potential porphyry copper sites. One hundred and seventy eight potential porphyry copper sites were mapped along the UDVB, and 23 sites were mapped along the CVB. The potential sites were selected to assist in further exploration and assessments of undiscovered porphyry copper deposits.

  17. Formation of a paleothermal anomaly and disseminated gold deposits associated with the Bingham Canyon porphyry Cu-Au-Mo system, Utah

    USGS Publications Warehouse

    Cunningham, C.G.; Austin, G.W.; Naeser, C.W.; Rye, R.O.; Ballantyne, G.H.; Stamm, R.G.; Barker, C.E.

    2004-01-01

    The thermal history of the Oquirrh Mountains, Utah, indicates that hydrothermal fluids associated with emplacement of the 37 Ma Bingham Canyon porphyry Cu-Au-Mo deposit extended at least 10 km north of the Bingham pit. An associated paleothermal anomaly enclosed the Barneys Canyon and Melco disseminated gold deposits and several smaller gold deposits between them. Previous studies have shown the Barneys Canyon deposit is near the outer limit of an irregular distal Au-As geochemical halo, about 3 km beyond an intermediate Pb-Zn halo, and 7 km beyond a proximal pyrite halo centered on the Bingham porphyry copper deposit. The Melco deposit also lies near the outer limit of the Au-As halo. Analysis of several geothermometers from samples collected tip to 22 km north of the Bingham Canyon porphyry Cu-Au-Mo deposit indicate that most sedimentary rocks of the Oquirrh Mountains, including those at the gold deposits, have not been regionally heated beyond the "oil window" (less than about 150??C). For geologically reasonable heating durations, the maximum sustained temperature at Melco, 6 km north of the Bingham pit, and at Barneys Canyon, 7.5 km north of the pit, was between 100??C and 140??C, as indicated by combinations of conodont color alteration indices of 1.5 to 2, mean random solid bitumen reflectance of about 1.0 percent, lack of annealing of zircon fission tracks, and partial to complete annealing of apatite fission tracks. The pattern of reset apatite fission-track ages indicates that the gold deposits are located approximately on the 120??C isotherm of the 37 Ma paleothermal anomaly assuming a heating duration of about 106 years. The conodont data further constrain the duration of heating to between 5 ?? 104 and 106 years at approximately 120??C. The ??18O of quartzite host rocks generally increases from about 12.6 per mil at the porphyry to about 15.8 per mil approximately 11 km from the Bingham deposit. This change reflects interaction of interstitial clays in

  18. U-Pb zircon, geochemical and Sr-Nd-Hf-O isotopic constraints on age and origin of the ore-bearing intrusions from the Nurkazgan porphyry Cu-Au deposit in Kazakhstan

    NASA Astrophysics Data System (ADS)

    Shen, Ping; Pan, Hongdi; Seitmuratova, Eleonora; Jakupova, Sholpan

    2016-02-01

    Nurkazgan, located in northeastern Kazakhstan, is a super-large porphyry Cu-Au deposit with 3.9 Mt metal copper and 229 tonnage gold. We report in situ zircon U-Pb age and Hf-O isotope data, whole rock geochemical and Sr-Nd isotopic data for the ore-bearing intrusions from the Nurkazgan deposit. The ore-bearing intrusions include the granodiorite porphyry, quartz diorite porphyry, quartz diorite, and diorite. Secondary ion mass spectrometry (SIMS) zircon U-Pb dating indicates that the granodiorite porphyry and quartz diorite porphyry emplaced at 440 ± 3 Ma and 437 ± 3 Ma, respectively. All host rocks have low initial 87Sr/86Sr ratios (0.70338-0.70439), high whole-rock εNd(t) values (+5.9 to +6.3) and very high zircon εHf(t) values (+13.4 to +16.5), young whole-rock Nd and zircon Hf model ages, and consistent and slightly high zircon O values (+5.7 to +6.7), indicating that the ore-bearing magmas derived from the mantle without old continental crust involvement and without marked sediment contamination during magma emplacement. The granodiorite porphyry and quartz diorite porphyry are enriched in large ion lithophile elements (LILE) and light rare earth elements (LREE) and depleted in high-field strength elements (HFSE), Eu, Ba, Nb, Sr, P and Ti. The diorite and quartz diorite have also LILE and LREE enrichment and HFSE, Nb and Ti depletion, but have not negative Eu, Ba, Sr, and P anomalies. These features suggest that the parental magma of the granodiorite porphyry and quartz diorite porphyry originated from melting of a lithospheric mantle and experienced fractional crystallization, whereas the diorite and quartz diorite has a relatively deeper lithospheric mantle source region and has not experienced strong fractional crystallization. Based on these, together with the coeval ophiolites in the area, we propose that a subduction of the Balkhash-Junggar oceanic plate took place during the Early Silurian and the ore-bearing intrusions and associated Nurkazgan

  19. Porphyry copper assessment of the Mesozoic of East Asia: China, Vietnam, North Korea, Mongolia, and Russia: Chapter G in Global mineral resource assessment

    USGS Publications Warehouse

    Ludington, Steve; Mihalasky, Mark J.; Hammarstrom, Jane M.; Robinson, Giplin R.; Frost, Thomas P.; Gans, Kathleen D.; Light, Thomas D.; Miller, Robert J.; Alexeiev, Dmitriy V.

    2012-01-01

    This report includes an overview of the assessment results and summary tables. Descriptions of each tract are included in appendixes, with estimates of numbers of undiscovered deposits, and probabilistic estimates of amounts of copper, molybdenum, gold, and silver that could be contained in undiscovered deposits for each permissive tract. A geographic information system that accompanies the report includes tract boundaries and a database of known porphyry copper deposits and prospects.

  20. A comparison of three-dimensional electrical conductivity models of several epithermal/porphyry type deposits in Western Canada, derived from ZTEM data

    NASA Astrophysics Data System (ADS)

    Huebert, J.; Lee, B.; Abbassi, B.; Liu, L.; Unsworth, M. J.; Richards, J. P.; Cheng, L.; Oldenburg, D.

    2013-12-01

    The Canadian Cordillera is host to numerous porphyry deposits which supply a substantial amount of the world's Cu, Mo and Au. With most near-surface mineralized systems already discovered, and in some cases mined, further exploration requires the development of geophysical deep-penetrating methods that can rapidly detect and characterize possible targets. The airborne Z-axis Tipper Electromagnetic (ZTEM) method with a penetration depth down to two kilometers is designed to image the electrical conductivity structure of the subsurface. The electrical response of mineral alterations associated with porphyry mineralization has shown to be more enigmatic than other deposit types. Therefore, the ZTEM data sets over three known Ag-Au epithermal/Cu-porphyry style deposits in British Columbia, Canada are analysed together with available geological information. In detail, we compare three-dimensional (3-D) models of electrical conductivity of the deposits, which were derived by the inversion of airborne ZTEM data and, where available, supported by ground MT data. The models are validated by petrophysical measurements and complemented by other geophysical models and geological evidence from borehole data.

  1. HRTEM/AEM study of trace metal behavior, sheet silicate reactions, and fluid/solid mass balances in porphyry copper hydrothermal systems

    SciTech Connect

    Veblen, D.R.; Ilton, E.S.

    1989-04-01

    Transmission electron microscopy has been used to investigate copper (Cu) incorporation into silicates and alteration reactions in porphyry copper deposits. High Cu in biotites results from submicroscopic inclusions of native Cu. The incorporation of Cu in low-temperature alteration lamellae suggests that Cu enrichment occurs during weathering, rather than during the hydrothermal event. Drill core from Cyprus Casa Grande, Arizona, shows systematic variation of Cu in sheet silicates as a function of depth in the weathering column. The aims of the present project are to apply the powerful techniques of transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and analytical electron microscopy (AEM) to understanding the geochemical processes in porphyry copper systems at the near-atomic scale. Our primary goals are to characterize the structural state of anomalously high Cu in silicates, determine the timing and conditions of Cu enrichment in silicates such as biotite, and use these data to suggest how base metals are released and subsequently immobilized under hydrothermal or weathering conditions; and to determine the submicroscopic, atomic-level reaction mechanisms responsible for silicate alteration in porphyry-copper hydrothermal systems, which will allow us to determine reaction stoichiometries and hence mass balances between minerals and hydrothermal fluid. 19 refs., 7 figs., 3 tabs.

  2. Mineralogy, textures, and whole-rock geochemistry of advanced argillic alteration: Hugo Dummett porphyry Cu-Au deposit, Oyu Tolgoi mineral district, Mongolia

    NASA Astrophysics Data System (ADS)

    Khashgerel, Bat-Erdene; Kavalieris, Imants; Hayashi, Ken-Ichiro

    2008-11-01

    Advanced argillic (AA) alteration is developed over a vertical interval of 500 m, above (and enclosing) Late Devonian quartz monzodiorite intrusions that accompany porphyry-style Cu-Au mineralization at the Hugo Dummett deposit. The AA alteration is mainly in basaltic rocks and locally extends into the overlying dacitic ash-flow tuff for about 100 m. The AA zone overprints porphyry-style quartz veins associated with quartz monzodiorite intrusions, but at least partly precedes high-grade porphyry-style bornite mineralization. Mineralogically, it consists of andalusite, corundum, residual quartz, titanium oxides, diaspore, alunite, aluminum phosphate-sulfate (APS) minerals, zunyite, pyrophyllite, topaz, kaolinite, and dickite, as well as anhydrite and gypsum, but is dominated by residual quartz and pyrophyllite. Alteration zonation is not apparent, except for an alunite-bearing zone that occurs approximately at the limit of strong quartz veining. Whole-rock geochemistry shows that the AA alteration removes most major elements except Si, Al, Ti, and P, and removes the trace elements Sc, Cs, and Rb. V, Zr, Hf, Nb, Ta, U, and Th are relatively immobile, whilst light REEs (La to Nd), Sr, Ba, and Ga can be enriched. Middle REEs (Sm to Gd) are moderately depleted; Y and heavy REEs (Tb to Lu) are strongly depleted except in two unusual samples where middle to heavy REEs are enriched.

  3. Double-layer mode of acid intrusive rocks from Xiuwacu Porphyry Mo deposit, Northwestern Yunnan SW China: U-Pb geochronology evidence

    NASA Astrophysics Data System (ADS)

    Yu, Haijun; Li, Wenchang

    2016-04-01

    Recent research infer that, the south-north extension of the Xiuwacu-Tongchanggou acidic intrusive belt along the Geza island arc have been developed of intense molybdenum-mutimetallic mineralization(Li et al., 2012, 2013; Yu et al., 2015). The northern section of this intrusive belt exposed widly and occur much monzonitic granite, biotite-granite, granodiorite, biotite-monzogranite; while in southern section, intrusions are cocealed. The Tongchanggou district in south section have been obtained large breakthrough of porphyry-skarn type molybdenum-multimetallic deposits exploration recent years(Yu et al., 2014), the Mo-W mineral resources also increased year after year in north section of the belt. The Mo-mineral resouree potential of porphyry-skarn type Mo-mutimetallic deposits in whole area are tremendous. Xiuwacu Porphyry molybdenum deposit was explored in Geza island arc, and widespread Biotite granite and monzonitic granite that is closely related to mineralization. We have understood poorly about this ore deposit for the harsh geographical circumstance, through, some referential result in chronology have accumulated, it still lack of systematic lithogeochemical study and reliable chronology data about intrusions. We yield biotite granite and monzonitic zircons U-Pb ages(200.93±0.65Ma, 83.57±0.32Ma, respectively) of Xiuwacu. There are two periods of intermediate-acid intrusive rocks of Xiuwacu area. Indosinian Biotite granite and Yanshanian monzonitic granite were formed as superposition phenomenon.

  4. Magmatic Vapor Phase Transport of Copper in Reduced Porphyry Copper-Gold Deposits: Evidence From PIXE Microanalysis of Fluid Inclusions

    NASA Astrophysics Data System (ADS)

    Rowins, S. M.; Yeats, C. J.; Ryan, C. G.

    2002-05-01

    Nondestructive proton-induced X-ray emission (PIXE) studies of magmatic fluid inclusions in granite-related Sn-W deposits [1] reveal that copper transport out of reduced felsic magmas is favored by low-salinity vapor and not co-existing high-salinity liquid (halite-saturated brine). Copper transport by magmatic vapor also has been documented in oxidized porphyry Cu-Au deposits, but the magnitude of Cu partitioning into the vapor compared to the brine generally is less pronounced than in the reduced magmatic Sn-W systems [2]. Consideration of these microanalytical data leads to the hypothesis that Cu and, by inference, Au in the recently established "reduced porphyry copper-gold" (RPCG) subclass should partition preferentially into vapor and not high-salinity liquid exsolving directly from fluid-saturated magmas [3-4]. To test this hypothesis, PIXE microanalysis of primary fluid inclusions in quartz-sulfide (pyrite, pyrrhotite & chalcopyrite) veins from two RPCG deposits was undertaken using the CSIRO-GEMOC nuclear microprobe. PIXE microanalysis for the ~30 Ma San Anton deposit (Mexico) was done on halite-saturated aqueous brine (<10 vol.% vapor) and co-existing low-salinity aqueous vapor (<20 vol.% liquid) inclusions. Results indicate that vapor inclusions have higher concentrations of Cu (typically 1000's of ppm; max. 7277 ppm) compared to brine inclusions (typically 100's of ppm). Brine inclusions also are much higher in Cl (Na), K, Ca, Mn, Zn, and Fe. Only Pb concentrations approach those in the vapor. Metal ratios such as Cu/Fe and Cu/Zn are 2 to 167 times higher in the vapor compared with the brine inclusions. Cu/Pb ratios are 2 to 15 times higher in the vapor than in the brine. PIXE microanalysis for the ~617 Ma 17 Mile Hill deposit (W. Australia) was done on halite-saturated "aqueous" inclusions, which contain a small (<10 vol.%) bubble of carbonic fluid, and adjacent "carbonic" inclusions, which have a thin rim of aqueous liquid (<10 vol.%) wetting the

  5. Geophysical model of the Cu-Mo porphyry ore deposit at Copper Flat Mine, Hillsboro, Sierra County, New Mexico

    NASA Astrophysics Data System (ADS)

    Gutierrez, Adrian Emmanuel Gutierrez

    A 3D gravity model of the Copper Flat Mine was performed as part of the exploration of new resources in at the mine. The project is located in the Las Animas Mining District in Sierra County, New Mexico. The mine has been producing ore since 1877 and is currently owned by the New Mexico Copper Corporation, which plans o bringing the closed copper mine back into production with innovation and a sustainable approach to mining development. The Project is located on the Eastern side of the Arizona-Sonora-New Mexico porphyry copper Belt of Cretaceous age. Copper Flat is predominantly a Cretaceous age stratovolcano composed mostly of quartz monzonite. The quartz monzonite was intruded by a block of andesite alter which a series of latite dikes creating veining along the topography where the majority of the deposit. The Copper Flat deposit is mineralized along a breccia pipe where the breccia is the result of auto-brecciation due to the pore pressure. There have been a number of geophysical studies conducted at the site. The most recent survey was a gravity profile on the area. The purpose of the new study is the reinterpretation of the IP Survey and emphasizes the practical use of the gravity geophysical method in evaluating the validity of the previous survey results. The primary method used to identify the deposit is gravity in which four Talwani models were created in order to created a 3D model of the ore body. The Talwani models have numerical integration approaches that were used to divide every model into polygons. The profiles were sectioned into polygons; each polygon was assigning a specific density depending on the body being drawn. Three different gridding techniques with three different filtering methods were used producing ten maps prior to the modeling, these maps were created to establish the best map to fit the models. The calculation of the polygons used an exact formula instead of the numerical integration of the profile made with a Talwani approach. A

  6. Genesis of ilmenite-series I-type granitoids at the Baogutu reduced porphyry Cu deposit, western Junggar, NW-China

    NASA Astrophysics Data System (ADS)

    Cao, MingJian; Qin, KeZhang; Li, GuangMing; Evans, Noreen J.; Hollings, Pete; Jin, LuYing

    2016-03-01

    The Baogutu porphyry Cu deposit is a typical reduced porphyry Cu deposit, likely related to ilmenite-series I-type granitoids. However, the nature of the granitoids (ilmenite-series or magnetite-series) and the genesis of the Baogutu deposit are still under debate. In order to resolve these issues, whole-rock magnetic susceptibility, geochemistry and Sr-Nd-Pb isotopic, zircon U-Pb dating and Hf-O isotopic compositions were carried out. Three different intrusive phases are recognized within the deposit, from oldest to youngest, they are diorite with trace gabbro, diorite-granodiorite porphyry, and hornblende diorite porphyry, all of which were emplaced in the Late Carboniferous (320-306 Ma) and show a metaluminous, calc-alkaline I-type granitoid character with typical supra-subduction zone geochemical affinities. The intrusions are characterized by widespread primary pyrrhotite without anhydrite and hematite, dominant ilmenite over magnetite, low whole rock magnetic susceptibility (< 1 × 10- 4 emu g- 1 oe- 1 or < 3 × 10- 3 SI unit) and low whole rock Fe2O3/FeO ratios (< 0.4), indicating that the granitoids are ilmenite- rather than magnetite-series I-type granitoids. Whole rock Sr-Nd-Pb isotopic compositions show limited variation but slightly enriched characteristics with (87Sr/86Sr)i values of 0.70357-0.70404, εNd (t) of + 6.3 to + 7.8, 206Pb/204Pb of 18.20-19.54 and 208Pb/204Pb of 37.97-39.55. Zircon Hf-O isotopic compositions show εHf (t) values of + 10.7 to + 15.8 and δ18O of 5.3-7.4‰. Zircon and apatite saturation thermometries yield temperatures of 720 to 920 °C with relatively higher temperatures for the porphyries than for the diorite. Limited variations in Sr-Nd-Pb-Hf-O isotopic compositions and extremely young whole rock T2DM (Nd) (430 to 570 Ma) and zircon TDMC (Hf) (310 to 640 Ma) do not indicate significant crustal contamination during magma ascent or emplacement. Rather the Baogutu ilmenite-series I-type granitoids were probably formed by

  7. The Mesozoic Caosiyao giant porphyry Mo deposit in Inner Mongolia, North China and Paleo-Pacific subduction-related magmatism in the northern North China Craton

    NASA Astrophysics Data System (ADS)

    Wu, Huaying; Zhang, Lianchang; Pirajno, Franco; Shu, Qihai; Zhang, Min; Zhu, Mingtian; Xiang, Peng

    2016-09-01

    The Caosiyao giant porphyry Mo deposit is located in the Wulanchabu area of Inner Mongolia, within the northern North China Craton (NCC). It contains more than 2385 Mt of ore with an average grade of 0.075% Mo. In the Caosiyao mining district, Mo mineralization occurs mainly in a Mesozoic granite porphyry as disseminations and stockworks, with some Mo distributed in Archean metamorphic rocks and diabase as stockworks and veins. The host granite porphyry is composed of two different phases that can be distinguished based on mineral assemblages and textures: one phase contains large and abundant phenocrysts (coarse-grained), while the other phase is characterized by fewer and smaller phenocrysts (medium-grained). Zircon U-Pb-Hf analyses of the former phase yielded a concordant 206Pb/238U age of 149.8 ± 2.4 Ma with a 206Pb/238U weighted mean age of 149.9 ± 2.4 Ma and εHf(t) values ranging from -12.2 to 18.3, while the latter phase gave a concordant 206Pb/238U age of 149.0 ± 2.2 Ma with a 206Pb/238U weighted mean age of 149.0 ± 2.1 Ma and εHf(t) values ranging from -13.1 to 17.7. Five samples of disseminated molybdenite have a 187Re-187Os isochron age of 149.5 ± 5.3 Ma with a weighted average age of 149.0 ± 1.8 Ma, whereas six veinlet-type molybdenite samples have a well-constrained 187Re-187Os isochron age of 146.9 ± 3.1 Ma and a weighted average age of 146.5 ± 0.8 Ma. Thus, it is suggested that the Mo mineralization of the Caosiyao deposit occurred during the Late Jurassic (ca. 147-149 Ma), almost coeval with the emplacement of the host granite porphyry (ca. 149-150 Ma). The host granite porphyry is characterized by high silica (SiO2 = 71.52-74.10 wt%), relatively high levels of oxidation (Fe2O3/FeO = 0.32-0.94 wt%) and high alkali element concentrations (Na2O + K2O = 8.21-8.76 wt%). The host granite porphyry also shows enrichments in U and K, and depletion in Ba, Sr, P, Eu, and Ti, suggesting strong fractional crystallization of plagioclase, biotite, and

  8. Stable isotope (S, O, H and C) studies of the phyllic and potassic phyllic alteration zones of the porphyry copper deposit at Sungun, East Azarbaidjan, Iran

    NASA Astrophysics Data System (ADS)

    Calagari, Ali Asghar

    2003-05-01

    The porphyry copper deposit (PCD) at Sungun is located in East Azarbaidjan, NW of Iran. The magmatic suites in the Sungun area are a part of the NW-SE trending Cenozoic magmatic belt of Iran. The Sungun porphyries occur as stocks and dikes. The stocks are divided into two groups, I and II. Porphyry Stock II, ranging in composition from quartz monzonite through granodiorite to granite, hosts the Sungun PCD. Four distinct types of hypogene alterations were recognized at Sungun: (1) potassic; (2) potassic-phyllic; (3) phyllic; and (4) propylitic. Stable isotope (S, O, H, and C) studies were restricted to within the phyllic and potassic-phyllic alteration zones, where numerous cross-cutting quartz, sulfides, carbonates, and sulfate veinlets are present. The objective of these studies was to determine the origin of the ore-forming solutions, and their important components (e.g. sulfur and carbon). Twenty sulfide and four sulfate samples were taken from sulfide and gypsum veinlets within Porphyry Stock II and the associated skarn zone for sulfur isotopic analyses. The δ34S values of sulfides (pyrite, chalcopyrite, molybdenite, galena, sphalerite) and sulfate (gypsum) range from -4.6 to -0.2‰ (mean of -1.5‰) and from 10.9 to 14.4‰ (mean of 12.9‰), respectively. These values are almost analogous to those from El Salvador (Chile) and Ajo (Arizona), and Twin Buttes (Arizona), and strongly suggest a magmatic source for the sulfur at Sungun. Twenty-eight fluid inclusion-rich quartz samples from quartz veinlets beneath the supergene zones of the Porphyry Stock II were chosen for O and H isotopic analyses. The δ18O (of quartz) and δD (of fluid inclusions in quartz) values range from 8.3 to 10.2‰ (mean of 9.2‰) and -58 to -75‰ (mean of -66‰) relative to Standard Mean Ocean Water (SMOW), respectively. The calculated δ18O values of the fluids range from 4.4‰ (T=375 ° C) to 7.6‰ (T=570 ° C) with a mean of 6.4‰. The δ18O and δD values of the fluids lie

  9. Mapping hydrothermal alteration using aircraft VNIR scanners at the Rosemont porphyry copper deposit. [Visible-Near Infrared

    NASA Technical Reports Server (NTRS)

    Sadowski, R. M.; Abrams, M. J.

    1983-01-01

    Two Visible-Near Infrared (VNIR) scanners, the NS-001 and the M2S, were flown over the Rosemont porphyry copper deposit as part of the NASA/JPL/GEOSAT test site program. This program was established to determine the feasibility and limitations of mapping hydrothermal alteration with multispectral scanners. Data from the NS-001 at 0.83 and 2.2 microns were used to identify Fe(3+) and OH enriched outcrops. These areas were then correlated with three alteration assemblages. The first correlation, hematite-epidote, was the most obvious and appeared as a strong ferric iron signature associated with hematite stained Cretaceous arkoses and andesites. The second correlation, qtz-sericite, showed a combined ferric-hydroxyl signature for a phyllicly altered quartz monzonite. The third correlation, skarn, was identified only after a review of calc-silicate mineral VNIR spectra. Altered limestones that outcrop west of the deposit have a similar ferric iron-hydroxyl signature as the quartz-sericite altered quartz monzonite. This skarn signature has been interpreted to indicate the presence of andradite, hydro-grossularite and idocrase. Data from the second scanner, M2S, was used to search for variation in ferric iron mineral type. Resulting imagery data indicated that hematite was the dominant ferric iron mineral present in the Rosemont area.

  10. Natural or Artificial? Multi-Analytical Study of a Scagliola from Estoi Palace Simulating Imperial Red Porphyry.

    PubMed

    Freire, Maria Teresa; Santos Silva, António; Veiga, Maria do Rosário; Brito, Jorge de; Schlütter, Frank

    2016-12-01

    In this paper the characterization of a gypsum plaster sample from the end of the 19th century simulating imperial red porphyry using a multi-analytical approach is presented and discussed. The results of X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TGA-DTA), physical and mechanical properties are summarized. In order to have further insight into the microstructure, polarized light microscopy (PLM), scanning electron microscopy coupled with energy dispersive X-ray spectrometer (SEM-EDS), and micro Raman spectroscopy analyzes were also made. They helped to clarify the main issues raised by the other complementary analytical techniques and allowed the establishment of interrelations between the different properties, providing important information about the materials, the skills, and the technological development involved in the art of imitating noble stones with gypsum pastes. This study also contributes to our knowledge concerning the preservation of these types of elements that are important in the context of European decorative arts and rarely reported in the literature.

  11. Geochemical Data for Samples Collected in 2008 Near the Concealed Pebble Porphyry Cu-Au-Mo Deposit, Southwest Alaska

    USGS Publications Warehouse

    Fey, David L.; Granitto, Matthew; Giles, Stuart A.; Smith, Steven M.; Eppinger, Robert G.; Kelley, Karen D.

    2009-01-01

    In the summer of 2007, the U.S. Geological Survey (USGS) began an exploration geochemical research study over the Pebble porphyry copper-gold-molybdenum deposit. This report presents the analytical data collected in 2008. The Pebble deposit is world class in size, and is almost entirely concealed by tundra, glacial deposits, and post-Cretaceous volcanic rocks. The Pebble deposit was chosen for this study because it is concealed by surficial cover rocks, is relatively undisturbed (except for exploration company drill holes), is a large mineral system, and is fairly well-constrained at depth by the drill hole geology and geochemistry. The goals of this study are to 1) determine whether the concealed deposit can be detected with surface samples, 2) better understand the processes of metal migration from the deposit to the surface, and 3) test and develop methods for assessing mineral resources in similar concealed terrains. The analytical data are presented as an integrated Microsoft Access 2003 database and as separate Excel files.

  12. Abundances of platinum group elements in native sulfur condensates from the Niuatahi-Motutahi submarine volcano, Tonga rear arc: Implications for PGE mineralization in porphyry deposits

    NASA Astrophysics Data System (ADS)

    Park, Jung-Woo; Campbell, Ian H.; Kim, Jonguk

    2016-02-01

    Some porphyry Cu-Au deposits, which are enriched in Pd, are potentially an economic source of Pd. Magmatic volatile phases are thought to transport the platinum group elements (PGEs) from the porphyry source magma to the point of deposition. However, the compatibilities of the PGEs in magmatic volatile phases are poorly constrained. We report PGE and Re contents in native sulfur condensates and associated altered dacites from the Niuatahi-Motutahi submarine volcano, Tonga rear arc, in order to determine the compatibility of PGEs and Re in magmatic volatile phases, and their mobility during secondary hydrothermal alteration. The native sulfur we analyzed is the condensate of a magmatic volatile phase exsolved from the Niuatahi-Motutahi magma. The PGEs are moderately enriched in the sulfur condensates in comparison to the associated fresh dacite, with enrichment factors of 11-285, whereas Au, Cu and Re are strongly enriched with enrichment factors of ∼20,000, ∼5000 and ∼800 respectively. Although the PGEs are moderately compatible into magmatic volatile phases, their compatibility is significantly lower than that of Au, Cu and Re. Furthermore, the compatibility of PGEs decrease in the order: Ru > Pt > Ir > Pd. This trend is also observed in condensates and sublimates from other localities. PGE mineralization in porphyry Cu-Au deposits is characterized by substantially higher Pd/Pt (∼7-60) and Pd/Ir (∼100-10,500) than typical orthomagmatic sulfide deposits (e.g. Pd/Pt ∼0.6 and Pd/Ir ∼20 for the Bushveld). It has previously been suggested that the high mobility of Pd, relative to the other PGEs, may account for the preferential enrichment of Pd in porphyry Cu-Au deposits. However, the low compatibility of Pd in the volatile phase relative to the other PGEs, shown in this study, invalidates this explanation. We suggest that the PGE geochemistry of Pd-rich Cu-Au deposits is principally derived from the PGE characteristics of the magma from which the ore

  13. Porphyry copper assessment of the Central Asian Orogenic Belt and eastern Tethysides: China, Mongolia, Russia, Pakistan, Kazakhstan, Tajikistan, and India: Chapter X in Global mineral resource assessment

    USGS Publications Warehouse

    Mihalasky, Mark J.; Ludington, Stephen; Hammarstrom, Jane M.; Alexeiev, Dmitriy V.; Frost, Thomas P.; Light, Thomas D.; Robinson,, Gilpin R.; Briggs, Deborah A.; Wallis, John C.; Miller, Robert J.; Bookstrom, Arthur A.; Panteleyev, Andre; Chitalin, Andre; Seltmann, Reimar; Guangsheng, Yan; Changyun, Lian; Jingwen, Mao; Jinyi, Li; Keyan, Xiao; Ruizhao, Qiu; Jianbao, Shao; Gangyi, Shai; Yuliang, Du

    2015-01-01

    The U.S. Geological Survey collaborated with international colleagues to assess undiscovered resources in porphyry copper deposits in the Central Asian Orogenic Belt and eastern Tethysides. These areas host 20 known porphyry copper deposits, including the world class Oyu Tolgoi deposit in Mongolia that was discovered in the late 1990s. The study area covers major parts of the world’s largest orogenic systems. The Central Asian Orogenic Belt is a collage of amalgamated Precambrian through Mesozoic terranes that extends from the Ural Mountains in the west nearly to the Pacific Coast of Asia in the east and records the evolution and final closure of the Paleo-Asian Ocean in Permian time. The eastern Tethysides, the orogenic belt to the south of the Central Asian Orogenic Belt, records the evolution of another ancient ocean system, the Tethys Ocean. The evolution of these orogenic belts involved magmatism associated with a variety of geologic settings appropriate for formation of porphyry copper deposits, including subduction-related island arcs, continental arcs, and collisional and postconvergent settings. The original settings are difficult to trace because the arcs have been complexly deformed and dismembered by younger tectonic events. Twelve mineral resource assessment tracts were delineated to be permissive for the occurrence of porphyry copper deposits based on mapped and inferred subsurface distributions of igneous rocks of specific age ranges and compositions. These include (1) nine Paleozoic tracts in the Central Asian Orogenic Belt, which range in area from about 60,000 to 800,000 square kilometers (km2); (2) a complex area of about 400,000 km2 on the northern margin of the Tethysides, the Qinling-Dabie tract, which spans central China and areas to the west, encompassing Paleozoic through Triassic igneous rocks that formed in diverse settings; and (3) assemblages of late Paleozoic and Mesozoic rocks that define two other tracts in the Tethysides, the 100

  14. Age and geochemistry of host rocks of the Cobre Panama porphyry Cu-Au deposit, central Panama: Implications for the Paleogene evolution of the Panamanian magmatic arc

    NASA Astrophysics Data System (ADS)

    Baker, Michael J.; Hollings, Peter; Thompson, Jennifer A.; Thompson, Jay M.; Burge, Colin

    2016-04-01

    The Cobre Panama porphyry Cu-Au deposit, located in the Petaquilla district of central Panama, is hosted by a sequence of medium- to high-K calc-alkaline volcanic and sub-volcanic rocks. New crystallisation ages obtained from a granodiorite Petaquilla batholith and associated mineralised diorite to granodiorite porphyry stocks and dikes at Cobre Panama indicate that the batholith was emplaced as a multi-phase intrusion, over a period of ~ 4 million years from 32.20 ± 0.76 Ma to 28.26 ± 0.61 Ma, while the porphyritic rocks were emplaced over a ~ 2 million year period from 28.96 ± 0.62 Ma to 27.48 ± 0.68 Ma. Both the volcanic to sub-volcanic host rocks and intrusive rocks of the Cobre Panama deposit evolved via fractional crystallisation processes, as demonstrated by the major elements (e.g. Al2O3, Fe2O3, TiO2 and MgO) displaying negative trends with increasing SiO2. The Petaquilla intrusive rocks, including the diorite-granodiorite porphyries and granodiorite batholith, are geochemically evolved and appear to have formed from more hydrous magmas than the preceding host volcanic rocks, as evidenced by the presence of hornblende phenocrysts, higher degrees of large-ion lithophile element (LILE) and light rare earth element (LREE) enrichment and heavy rare earth element (HREE) depletion, and higher Sr/Y and La/Yb values. However, the degree of LREE enrichment, HREE depletion and La/Yb values are insufficient for the intrusive rocks to be considered as adakites. Collectively, the volcanic and intrusive rocks have LILE, REE and mobile trace element concentrations similar to enriched Miocene-age Cordilleran arc magmatism found throughout central and western Panama. Both the Petaquilla and Cordilleran arc magmatic suites are geochemically more evolved than the late Cretaceous to Eocene Chagres-Bayano arc magmas from northeastern Panama, as they display higher degrees of LILE and LREE enrichment. The geochemical similarities between the Petaquilla and Cordilleran arc

  15. Geochemical behavior of rare earth elements of the hydrothermal alterations within the Tepeoba porphyry Cu-Mo-Au deposits at Balikesir, NW Turkey

    NASA Astrophysics Data System (ADS)

    Doner, Zeynep; Abdelnasser, Amr; Kiran Yildirim, Demet; Kumral, Mustafa

    2016-04-01

    This work reports the geochemical characteristics and behavior of the rare earth elements (REE) of the hydrothermal alteration of the Tepeoba porphyry Cu-Mo-Au deposit located in the Anatolian tectonic belt at Biga peninsula (Locally Balikesir province), NW Turkey. The Cu-Mo-Au mineralization at this deposit hosted in the hornfels rocks and related to the silicic to intermediate intrusion of Eybek pluton. It locally formed with brecciated zones and quartz vein stockworks, as well as the brittle fracture zones associated with intense hydrothermal alteration. Three main alteration zones with gradual boundaries formed in the mine area in the hornfels rock that represents the host rock, along that contact the Eybek pluton; potassic, propylitic and phyllic alteration zones. The potassic alteration zone that formed at the center having high amount of Cu-sulfide minerals contains biotite, muscovite, and sericite with less amount of K-feldspar and associated with tourmalinization alteration. The propylitic alteration surrounds the potassic alteration having high amount of Mo and Au and contains chlorite, albite, epidote, calcite and pyrite. The phyllic alteration zone also surrounds the potassic alteration containing quartz, sericite and pyrite minerals. Based on the REE characteristics and content and when we correlate the Alteration index (AI) with the light REEs and heavy REEs of each alteration zone, it concluded that the light REEs decrease and heavy REEs increase during the alteration processes. The relationships between K2O index with Eu/Eu* and Sr/Sr* reveals a positive correlation in the potassic and phyllic alteration zones and a negative correlation in the propylitic alteration zone. This refers to the hydrothermal solution which is responsible for the studied porphyry deposits and associated potassic and phyllic alterations has a positive Eu and Sr anomaly as well as these elements were added to the altered rock from the hydrothermal solution. Keywords: Rare

  16. Using the concentration-volume (C-V) fractal model in the delineation of gold mineralized zones within the Tepeoba porphyry Cu-Mo-Au, Balikesir, NW Turkey

    NASA Astrophysics Data System (ADS)

    Kumral, Mustafa; Abdelnasser, Amr; Karaman, Muhittin; Budakoglu, Murat

    2016-04-01

    The Tepeoba porphyry Cu-Mo-Au mineralization that located at the Biga peninsula (W Turkey) developed around the Eybek pluton concentrated at its southern contact. This mineralization that hosted in the hornfels rocks of Karakaya Complex is associated with three main alteration zones; potassic, phyllic and propylitic alterations along the fault controlled margins of the Eybek pluton and quartz stockwork veining as well as brecciation zones. As well as two mineralized zones were occurred in the mine area; hypogene and oxidation/supergene zone. The hypogene zone has differentiated alteration types; high potassic and low phyllic alteration, while the oxidation/supergene zone has high phyllic and propylitic alterations. This work deals with the delineation of gold mineralized zone within this porphyry deposit using the concentration-volume (C-V) fractal model. Five zones of gold were calculated using its power-law C-V relationship that revealed that the main phase of gold mineralization stated at 5.3083 ppm Au concentration. In addition, the C-V log-log plot shows that the highly and moderately Au mineralization zone developed in western part of deposit correlated with oxidation zone related to propylitic alteration. On the other hand, its weakly mineralization zone has a widespread in the hypogene zone related to potassic alteration. This refers to the enrichment of gold and depletion of copper at the oxidation/supergene zone is due to the oxidation/supergene alteration processes that enrich the deposits by the meteoric water. Keywords: Concentration-volume (C-V) fractal model; gold mineralized zone; Tepeoba porphyry Cu-Mo-Au; Balikesir; NW Turkey.

  17. The partitioning of copper among selected phases of geologic media of two porphyry copper districts, Puerto Rico

    USGS Publications Warehouse

    Learned, R.E.; Chao, T.T.; Sanzolone, R.F.

    1981-01-01

    In experiments designed to determine the manner in which copper is partitioned among selected phases that constitute geologic media, we have applied the five-step sequential extraction procedure of Chao and Theobald to the analysis of drill core, soils, and stream sediments of the Rio Vivi and Rio Tanama porphyry copper districts of Puerto Rico. The extraction procedure affords a convenient means of determining the trace-metal content of the following fractions: (1) Mn oxides and "reactive" Fe oxides; (2) "amorphous" Fe oxides; (3) "crystalline" Fe oxides; (4) sulfides and magnetite; and (5) silicates. An additional extraction between steps (1) and (2) was performed to determine organic-related copper in stream sediments. The experimental results indicate that apportionment of copper among phases constituting geologic media is a function of geochemical environment. Distinctive partitioning patterns were derived from the analysis of drill core from each of three geochemical zones: (a) the supergene zone of oxidation; (b) the supergene zone of enrichment; and (c) the hypogene zone; and similarly, from the analysis of; (d) soils on a weakly leached capping; (e) soils on a strongly leached capping; and (f) active stream sediment. The experimental results also show that geochemical contrasts (anomaly-to-background ratios) vary widely among the five fractions of each sampling medium investigated, and that at least one fraction of each medium provides substantially stronger contrast than does the bulk medium. Fraction (1) provides optimal contrast for stream sediments of the district; fraction (2) provides optimal contrast for soils on a weakly leached capping; fraction (3) provides optimal contrast for soils on a strongly leached capping. Selective extraction procedures appear to have important applications to the orientation and interpretive stages of geochemical exploration. Further investigation and testing of a similar nature are recommended. ?? 1981.

  18. Mineralogical study on volcanic ash of the eruption on September 27, 2014 at Ontake volcano, central Japan: correlation with porphyry copper systems

    NASA Astrophysics Data System (ADS)

    Minami, Yusuke; Imura, Takumi; Hayashi, Shintaro; Ohba, Tsukasa

    2016-04-01

    The volcanic ash of the eruption on September 27, 2014 at Ontake volcano consists mostly of altered rock fragments. The ash contains partly altered volcanic rock fragments consisting of primary igneous minerals (plagioclase, orthopyroxene, titanomagnetite, and feldspars) and volcanic glass accompanied by alteration minerals to some extents, and contains no juvenile fragments. These features indicate that the eruption was a non-juvenile hydrothermal eruption that was derived from the hydrothermal system developed under the crater. The major minerals derived from hydrothermal alteration zones are silica mineral, kaolin-group mineral, smectite, pyrophyllite, muscovite, alunite, anhydrite, gypsum, pyrite, K-feldspar, albite, and rutile. Minor chlorite, biotite, and garnet are accompanied. Five types of alteration mineral associations are identified from observations on individual ash particles: silica-pyrite, silica-pyrite ± alunite ± kaolin, silica-pyrophyllite-pyrite, silica-muscovite ± chlorite, and silica-K-feldspar ± albite ± garnet ± biotite. The associations indicate development of advanced argillic, sericite, and potassic alteration zones under the crater. Occurrence of anhydrite veinlet and the set of alteration zones indicate hydrothermal alteration zones similar to late-stage porphyry copper systems. Comparing the mineral associations with the geologic model of the late-stage porphyry copper systems, the source depths of mineral associations are estimated to range from near surface to >2 km. The depths of advanced argillic alteration, sericite, and potassic zones are 0 to ~2, ~1.5 to ~2, and >2 km, respectively.

  19. An exploration hydrogeochemical study at the giant Pebble porphyry Cu-Au-Mo deposit, Alaska, USA, using high-resolution ICP-MS

    USGS Publications Warehouse

    Eppinger, Robert G.; Fey, David L.; Giles, Stuart A.; Kelley, Karen D.; Smith, Steven M.

    2012-01-01

    A hydrogeochemical study using high resolution ICP-MS was undertaken at the giant Pebble porphyry Cu-Au-Mo deposit and surrounding mineral occurrences. Surface water and groundwater samples from regional background and the deposit area were collected at 168 sites. Rigorous quality control reveals impressive results at low nanogram per litre (ng/l) levels. Sites with pH values below 5.1 are from ponds in the Pebble West area, where sulphide-bearing rubble crop is thinly covered. Relative to other study area waters, anomalous concentrations of Cu, Cd, K, Ni, Re, the REE, Tl, SO42− and F− are present in water samples from Pebble West. Samples from circum-neutral waters at Pebble East and parts of Pebble West, where cover is much thicker, have anomalous concentrations of Ag, As, In, Mn, Mo, Sb, Th, U, V, and W. Low-level anomalous concentrations for most of these elements were also found in waters surrounding nearby porphyry and skarn mineral occurrences. Many of these elements are present in low ng/l concentration ranges and would not have been detected using traditional quadrupole ICP-MS. Hydrogeochemical exploration paired with high resolution ICP-MS is a powerful new tool in the search for concealed deposits.

  20. Magmatic-hydrothermal fluids and volatile metals in the Spirit Lake pluton and Margaret Cu-Mo porphyry system, SW Washington, USA

    NASA Astrophysics Data System (ADS)

    Iveson, Alexander A.; Webster, James D.; Rowe, Michael C.; Neill, Owen K.

    2016-03-01

    The halogen-bearing minerals tourmaline, amphibole, and biotite formed during magmatic-hydrothermal processes associated with the late-stage cooling of the Spirit Lake granitoid pluton (Mt. St. Helens, WA) and with the younger sulphide-mineralised rocks of the Margaret Cu-Mo porphyry deposit located entirely within the pluton. Major- and trace-element discrimination suggests that one tourmaline population crystallised from fractionated late-stage melt pockets in granodiorite-monzogranitic dykes of the pluton. These coarse, euhedral, oscillatory, and complexly sector-zoned uvite tourmalines span a limited range in Mg/(Mg + Fe) [Mg#] space (0.4-0.7 apfu) and show the highest Ti, Ca, F, Nb, and Ta contents, and low X-site vacancies (<0.1 apfu), suggesting slow, ordered crystallisation. Conversely, smaller, microcrystalline, pluton-related vein tourmalines show higher X-site vacancies (>0.6 apfu), lower Ca and F contents, and the highest Li, As, and HREE contents (>80 ppm Li, >1200 ppm As). This population appears to record direct, rapid crystallisation from magmatic ± meteoric fluid(s) bearing the signature of the breakdown of primary feldspars and pyroxenes, with fluid exsolution from fractionated melt patches likely triggered by the formation of the previous generation of tourmaline. Mineralised porphyry deposit tourmaline compositions from the stockwork span a much larger range in Mg# space (0.05-0.9 apfu) and are almost entirely Ca-free. X-sites of these schorl tourmalines are dominated by Na or vacancies, and the Y-sites are strongly Fe enriched. The highest Mn and Zn concentrations (>4000 and >1000 ppm, respectively) potentially reflect the composition of mineralising fluids during ore deposition. A number of boron isotopic analyses yield predominantly heavy boron, but δ11B values range from -5.2 to 6.2 ‰ and average 1.4 ‰. Whilst most plutonic tourmalines conform to reported a- and c-sector element partitioning models, those from the mineralised porphyry

  1. Intensity of quartz cathodoluminescence and trace-element content in quartz from the porphyry copper deposit at Butte, Montana

    USGS Publications Warehouse

    Rusk, B.G.; Reed, M.H.; Dilles, J.H.; Kent, A.J.R.

    2006-01-01

    Textures of hydrothermal quartz revealed by cathodoluminescence using a scanning electron microscope (SEM-CL) reflect the physical and chemical environment of quartz formation. Variations in intensity of SEM-CL can be used to distinguish among quartz from superimposed mineralization events in a single vein. In this study, we present a technique to quantify the cathodoluminescent intensity of quartz within individual and among multiple samples to relate luminescence intensity to specific mineralizing events. This technique has been applied to plutonic quartz and three generations of hydrothermal veins at the porphyry copper deposit in Butte, Montana. Analyzed veins include early quartz-molybdenite veins with potassic alteration, pyrite-quartz veins with sericitic alteration, and Main Stage veins with intense sericitic alteration. CL intensity of quartz is diagnostic of each mineralizing event and can be used to fingerprint quartz and its fluid inclusions, isotopes, trace elements, etc., from specific mineralizing episodes. Furthermore, CL intensity increases proportional to temperature of quartz formation, such that plutonic quartz from the Butte quartz monzonite (BQM) that crystallized at temperatures near 750 ??C luminesces with the highest intensity, whereas quartz that precipitated at ???250 ??C in Main Stage veins luminesces with the least intensity. Trace-element analyses via electron microprobe and laser ablation-ICP-MS indicate that plutonic quartz and each generation of hydrothermal quartz from Butte is dominated by characteristic trace amounts of Al, P, Ti, and Fe. Thus, in addition to CL intensity, each generation of quartz can be distinguished based on its unique trace-element content. Aluminum is generally the most abundant element in all generations of quartz, typically between 50 and 200 ppm, but low-temperature, Main Stage quartz containing 400 to 3600 ppm Al is enriched by an order of magnitude relative to all other quartz generations. Phosphorous

  2. Geochemical characteristics of the Shujiadian Cu deposit related intrusion in Tongling: Petrogenesis and implications for the formation of porphyry Cu systems in the Middle-Lower Yangtze River Valley metallogenic belt, eastern China

    NASA Astrophysics Data System (ADS)

    Wang, Shiwei; Zhou, Taofa; Yuan, Feng; Fan, Yu; Cooke, David R.; Zhang, Lejun; Fu, Bin; White, Noel C.

    2016-05-01

    Porphyry Cu deposits can form in intracontinental or post-collision settings; however, both the genesis of fertile magmas and the mechanism of metal enrichment remain controversial. The Shujiadian porphyry Cu deposit is located in the Tongling area of the Middle-Lower Yangtze River Valley metallogenic belt. It is hosted by the Shujiadian complex, which mainly consists of quartz diorite porphyry (143.7 ± 1.7 Ma) and pyroxene diorite (139.8 ± 1.6 Ma). They both belong to the calc-alkaline series, with enrichment in large-ion lithophile elements (LILE) and light rare earth elements (LREE), depletion in high field-strength elements (HFSE) and heavy rare earth elements (HREE), and slightly negative Eu anomalies. Both quartz diorite porphyry and pyroxene diorite have geochemical affinities with adakite, and their low MgO (1.5-3.7 wt%), and Ni (3.7-6.9 ppm), Cr (2.0-44 ppm), and Th/Ce contents (0.06-0.11) indicate that the intrusive rocks have some characteristics of adakite-like rocks derived from thickened lower crust and melts from metabasaltic rocks and eclogites. Plagioclases from the quartz diorite porphyry are andesine (An value = 31.8-40.5) and from the pyroxene diorite are felsic albite and oligoclase with large-scale zones and variable An value (An value = 8.9-18.3), Fe and Sr contents, which indicate that mixing of mafic and felsic magma may have occurred in the shallow magma chamber. Compared to the barren quartz diorite porphyry, relatively lower SiO2 contents (49.5-55.2 wt.%), higher εNd(t) values (- 7.4 to - 6.9), εHf(t) values (- 11.0 to - 9.1) compositions, Ti-in-zircon temperatures (714-785 °C), and variations of HREE contents of the mineralization-related pyroxene diorite suggest mixing with high-temperature mafic magma. Calculated Ce4 +/Ce3 + values of pyroxene diorite plot between the Ni-NiO buffer (NNO) and magnetite-hematite buffer (MH), and barren quartz diorite porphyry samples plot below the Ni-NiO buffer (NNO). Geochemical features of

  3. Mineralogical, stable isotope, and fluid inclusion studies of spatially related porphyry Cu and epithermal Au-Te mineralization, Fakos Peninsula, Limnos Island, Greece

    NASA Astrophysics Data System (ADS)

    Fornadel, Andrew P.; Voudouris, Panagiotis Ch.; Spry, Paul G.; Melfos, Vasilios

    2012-05-01

    The Fakos porphyry Cu and epithermal Au-Te deposit, Limnos Island, Greece, is hosted in a ~20 Ma quartz monzonite and shoshonitic subvolcanic rocks that intruded middle Eocene to lower Miocene sedimentary basement rocks. Metallic mineralization formed in three stages in quartz and quartz-calcite veins. Early porphyry-style (Stage 1) metallic minerals consist of pyrite, chalcopyrite, galena, bornite, sphalerite, molybdenite, and iron oxides, which are surrounded by halos of potassic and propylitic alteration. Stage 2 mineralization is composed mostly of quartz-tourmaline veins associated with sericitic alteration and disseminated pyrite and molybdenite, whereas Stage 3, epithermal-style mineralization is characterized by polymetallic veins containing pyrite, chalcopyrite, sphalerite, galena, enargite, bournonite, tetrahedrite-tennantite, hessite, petzite, altaite, an unknown cervelleite-like Ag-telluride, native Au, and Au-Ag alloy. Stage 3 veins are spatially associated with sericitic and argillic alteration. Fluid inclusions in quartz from Stage 1 (porphyry-style) mineralization contain five types of inclusions. Type I, liquid-vapor inclusions, which homogenize at temperatures ranging from 189.5°C to 403.3°C have salinities of 14.8 to 19.9 wt. % NaCl equiv. Type II, liquid-vapor-NaCl, Type III liquid-vapor-NaCl-XCl2 (where XCl is an unknown chloride phase, likely CaCl2), and Type IV, liquid-vapor-hematite ± NaCl homogenize to the liquid phase by liquid-vapor homogenization or by daughter crystal dissolution at temperatures of 209.3 to 740.5 °C, 267.6 to 780.8 °C, and 357.9 to 684.2 °C, respectively, and, Type V, vapor-rich inclusions. Stage 2 veins are devoid of interpretable fluid inclusions. Quartz from Stage 3 (epithermal-style) veins contains two types of fluid inclusions, Type I, liquid-vapor inclusions that homogenize to the liquid phase (191.6 to 310.0 °C) with salinities of 1.40 to 9.73 wt. % NaCl equiv., and Type II, vapor-rich inclusions. Mixing

  4. Geochronology, geochemistry and Sr-Nd-Pb isotopic constraints on the origin of the Qian’echong porphyry Mo deposit, Dabie orogen, east China

    NASA Astrophysics Data System (ADS)

    Gao, Yang; Mao, Jingwen; Ye, Huishou; Li, Faling; Li, Yongfeng; Luo, Zhengzhuan; Xiong, Bikang; Meng, Fang

    2014-05-01

    The giant Qian’echong porphyry molybdenum deposit is located in the Dabie orogen, east China. The molybdenum mineralization mainly occurs as molybdenite-bearing quartz veins hosted by the Devonian Nanwan Formation in the external contact zone of the Qian’echong stock. The Qian’echong stock comprises an earlier formed monzogranite and a later formed granite porphyry. Sensitive high-resolution ion microprobe (SHRIMP) zircon U-Pb dating constrains the timing of crystallization of the monzogranite and granite porphyry to 130 ± 2 and 129 ± 2 Ma, respectively. The Re-Os model ages of six molybdenite samples range from 127.9 ± 1.9 to 129.7 ± 1.9 Ma with an isochron age of 129.4 ± 1.5 Ma, which are all consistent within errors with the zircon U-Pb ages, indicating an Early Cretaceous magmatic and mineralization event. The Qian’echong granites have moderate negative Eu anomalies and are relatively enriched in light rare earth elements (REE), but depleted in heavy REE, Y, and high field strength elements (HFSE; e.g., Nb, Ta, and Ti). The Qian’echong granites are I-type rather than A- or S-type, and they have high (87Sr/86Sr)i (0.706771-0.710326) and low ɛNd(t) (-25.5 to -16.8). Two-stage Nd model ages (T2DM) vary between 2.29 and 2.99 Ga. Sr-Nd-Pb isotopic data suggest that the Qian’echong granites were not derived from the North China Craton (NCC), but rather were generated from the Yangtze Craton (YC) lower crust. Paleoproterozoic inherited zircon age and whole-rock chemical and Sr-Nd-Pb isotopic data suggest that the Qian’echong granites were derived mainly from partial melting of ultrahigh pressure eclogites, with incorporation of some Paleoproterozoic to Archean YC crustal materials at lower crustal levels. Delamination or foundering of eclogitic lower crust, which extensively occurred in the Dabie orogen during the Early Cretaceous, had not taken place beneath the Qian’echong deposit when it formed. The Qian’echong molybdenum deposit formed in

  5. Coarse muscovite veins and alteration deep in the Yerington batholith, Nevada: insights into fluid exsolution in the roots of porphyry copper systems

    NASA Astrophysics Data System (ADS)

    Runyon, Simone E.; Steele-MacInnis, Matthew; Seedorff, Eric; Lecumberri-Sanchez, Pilar; Mazdab, Frank K.

    2017-02-01

    Veins and pervasive wall-rock alteration composed of coarse muscovite±quartz±pyrite are documented for the first time in a porphyritic granite at Luhr Hill in the Yerington District, Nevada. Coarse muscovite at Luhr Hill occurs at paleodepths of 6-7 km in the roots of a porphyry copper system and crops out on the scale of tens to hundreds of meters, surrounded by rock that is unaltered or variably altered to sodic-calcic assemblages. Coarse muscovite veins exhibit a consistent orientation, subvertical and N-S striking, which structurally restores to subhorizontal at the time of formation. Along strike, coarse muscovite veins swell from distal, millimeter-thick muscovite-only veinlets to proximal, centimeter-thick quartz-sulfide-bearing muscovite veins. Crosscutting relationships between coarse muscovite veins, pegmatite dikes, and sodic-calcic veins indicate that muscovite veins are late-stage magmatic-hydrothermal features predating final solidification of the Luhr Hill porphyritic granite. Fluid inclusions in the muscovite-quartz veins are high-density aqueous inclusions of 3-9 wt% NaCl eq. and <1 mol% CO2 that homogenize between 150 and 200 °C, similar to fluid inclusions from greisen veins in Sn-W-Mo vein systems. Our results indicate that muscovite-forming fluids at Luhr Hill were mildly acidic, of low to moderate salinity and sulfur content and low CO2 content, and that muscovite in deep veins and alteration differs in texture, composition, and process of formation from sericite at shallower levels of the hydrothermal system. Although the definition of greisen is controversial, we suggest that coarse muscovite alteration is more similar to alteration in greisen-type Sn-W-Mo districts worldwide than to sericitic alteration at higher levels of porphyry copper systems. The fluids that form coarse muscovite veins and alteration in the roots of porphyry copper systems are distinct from fluids that formed copper ore or widespread, shallower, acidic alteration

  6. SHRIMP U-Pb and Ar-Ar geochronology of major porphyry and skarn Cu deposits in the Balkhash Metallogenic Belt, Central Asia, and geological implications

    NASA Astrophysics Data System (ADS)

    Chen, Xuanhua; Seitmuratova, Eleonora; Wang, Zhihong; Chen, Zhengle; Han, Shuqin; Li, Yong; Yang, Yi; Ye, Baoying; Shi, Wei

    2014-01-01

    The Balkhash Metallogenic Belt (BMB) in Kazakhstan, Central Asia, with the occurrence of the super-large Kounrad and Aktogai, the large Borly porphyry Cu-Mo deposits, and the large Sayak skarn polymetallic ore-field, is one of the central regions of the Paleozoic Central Asian metallogenic domain and orogenic belt. In this study, newly obtained SHRIMP zircon U-Pb ages of nine samples and 40Ar/39Ar ages of six mineral samples (inclding hornblende, biotite and K-feldspar) give more detailed constraints on the timing of the granitic intrusions and their metallogeny. Porphyritic monzonite granite and tonalite porphyry from the Kounrad deposit yield U-Pb zircon SHRIMP ages of 327.3 ± 2.1 Ma and 308.7 ± 2.2 Ma, respectively. Quartz diorite and porphyritic granodiorite from the Aktogai deposit yield U-Pb SHRIMP ages of 335.7 ± 1.3 Ma and 327.5 ± 1.9 Ma, respectively. Porphyritic granodiorite and granodiorite from the Borly deposit yield U-Pb SHRIMP ages of 316.3 ± 0.8 Ma and 305 ± 3 Ma, respectively. Diorite, granodiorite, and monzonite from the Sayak ore-field yield U-Pb SHRIMP ages of 335 ± 2 Ma, 308 ± 10 Ma, and 297 ± 3 Ma, respectively. Hornblende, biotite, and K-feldspar from the Aktogai deposit yield 40Ar/39Ar cooling ages of 310.6 Ma, 271.5 Ma, and 274.9 Ma, respectively. Hornblende, biotite, and K-feldspar from the Sayak ore-field yield 40Ar/39Ar cooling ages of 287.3 ± 2.8 Ma, 307.9 ± 1.8 Ma, and 249.8 ± 1.6 Ma, respectively. The new ages constrain the timing of Late Paleozoic felsic magmatism to ˜336 to ˜297 Ma. Skarn mineralization in the Sayak ore-field formed at ˜335 and ˜308 Ma. Porphyry Cu-Mo mineralization in the Kounrad deposit and the Aktogai deposit formed at ˜327 Ma, and in the Borly deposit at ˜316 Ma. The Late Paleozoic regional cooling in the temperature range of ˜600 °C to ˜150 °C occurred from ˜307 to ˜257 Ma.

  7. Two-types of Early Cretaceous adakitic porphyries from the Luxi terrane, eastern North China Block: Melting of subducted Paleo-Pacific slab and delaminated newly underplated lower crust

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Xu, Zhaowen; Lu, Xiancai; Fu, Bin; Lu, Jianjun; Yang, Xiaonan; Zhao, Zengxia

    2016-01-01

    The origin and tectonic setting of Early Cretaceous adakitic rocks from the Luxi terrane in the eastern North China Block (NCB) remain debated. To resolve this issue, we determined whole-rock geochemistry, zircon U-Pb ages, and in situ Hf-O isotopes of the Mengyin and Liujing adakitic porphyries from the Luxi terrane. Zircon U-Pb dating results reveal that both the Mengyin and Liujing plutons were emplaced during the Early Cretaceous, with weighted mean 206Pb/238U ages of 130 ± 1 Ma (2σ) and 131 ± 2 Ma (2σ), respectively. In addition, abundant Neoarchean-Paleoproterozoic inherited zircon cores are identified in the Mengyin adakitic porphyry with 207Pb/206Pb ages ranging from 2.53 to 2.42 Ga. Rocks of both plutons are silicic (SiO2 = 65.4-70.2 wt.%), metaluminous, and alkaline in composition, comprising mainly quartz syenite porphyries. Samples from both plutons are enriched in large ion lithophile elements (LILEs) (e.g., Rb, Sr, and Ba), and light rare earth elements (LREEs), depleted in high field strength elements (HFSEs) (e.g., Nb, Ta, and Ti), and heavy rare earth elements (HREEs), and have either positive or no Eu anomalies. In addition, both adakitic porphyries have high Mg# values (51-64), high Sr and La contents, low Y and Yb contents, and high Sr/Y (Mengyin = 149-264; Liujing = 58-110) and (La/Yb)N (Mengyin = 32.4-45.3; Liujing = 43.8-53.1) ratios, similar to adakitic rocks worldwide. The Mengyin adakitic porphyry has higher whole-rock εNd(t) values (-5.8 to - 4.1), more radiogenic Pb [(206Pb/204Pb)i = 18.35-18.39, (207Pb/204Pb)i = 15.55-15.56, (208Pb/204Pb)i = 38.20-38.23], higher zircon rim εHf(t) values (+ 3.3 to + 8.8) and δ18O values (+ 6.5‰ to + 7.9‰), and lower (87Sr/86Sr)i ratios (0.7049-0.7050) than the Liujing adakitic porphyry [εNd(t) = - 12.4 to - 12.2, (206Pb/204Pb)i = 17.63-17.72, (207Pb/204Pb)i = 15.56-15.58, (208Pb/204Pb)i = 37.76-37.94, εHf(t) = - 14.8 to - 11.2, δ18O = + 5.9‰ to + 7.1‰, (87Sr/86Sr)i = 0.7090-0.7091]. The

  8. Production of sulfur gases and carbon dioxide by synthetic weathering of crushed drill cores from the Santa Cruz porphyry copper deposit near Casa Grande, Pinal County, Arizona

    USGS Publications Warehouse

    Hinkle, M.E.; Ryder, J.L.; Sutley, S.J.; Botinelly, T.

    1990-01-01

    Samples of ground drill cores from the southern part of the Santa Cruz porphyry copper deposit, Casa Grande, Arizona, were oxidized in simulated weathering experiments. The samples were also separated into various mineral fractions and analyzed for contents of metals and sulfide minerals. The principal sulfide mineral present was pyrite. Gases produced in the weathering experiments were measured by gas chromatography. Carbon dioxide, oxygen, carbonyl sulfide, sulfur dioxide and carbon disulfide were found in the gases; no hydrogen sulfide, organic sulfides, or mercaptans were detected. Oxygen concentration was very important for production of the volatiles measured; in general, oxygen concentration was more important to gas production than were metallic element content, sulfide mineral content, or mineral fraction (oxide or sulfide) of the sample. The various volatile species also appeared to be interactive; some of the volatiles measured may have been formed through gas reactions. ?? 1990.

  9. Geophysical and geochemical data from the area of the Pebble Cu-Au-Mo porphyry deposit, southwestern Alaska: Contributions to assessment techniques for concealed mineral resources

    USGS Publications Warehouse

    Anderson, E.D.; Smith, S.M.; Giles, S.A.; Granitto, Matthew; Eppinger, R.G.; Bedrosian, P.A.; Shah, A.K.; Kelley, K.D.; Fey, D.L.; Minsley, B.J.; Brown, P.J.

    2011-01-01

    In 2007, the U.S. Geological Survey began a multidisciplinary study in southwest Alaska to investigate the setting and detectability of mineral deposits in concealed volcanic and glacial terranes. The study area hosts the world-class Pebble porphyry Cu-Au-Mo deposit, and through collaboration with the Pebble Limited Partnership, a range of geophysical and geochemical investigations was carried out in proximity to the deposit. The deposit is almost entirely concealed by tundra, glacial deposits, and post-mineralization volcanic rocks. The discovery of mineral resources beneath cover is becoming more important because most of the mineral resources at the surface have already been discovered. Research is needed to identify ways in which to assess for concealed mineral resources. This report presents the uninterpreted geophysical measurements and geochemical and mineralogical analytical data from samples collected during the summer field seasons from 2007 to 2010, and makes the data available in a single Geographic Information System (GIS) database.

  10. Hydrothermal modification of host rock geochemistry within Mo-Cu porphyry deposits in the Galway Granite, western Ireland

    NASA Astrophysics Data System (ADS)

    Tolometti, Gavin; McCarthy, Will

    2016-04-01

    Hydrothermal alteration of host rock is a process inherent to the formation of porphyry deposits and the required geochemical modification of these rocks is regularly used to indicate proximity to an economic target. The study involves examining the changes in major, minor and trace elements to understand how the quartz vein structures have influenced the chemistry within the Murvey Granite that forms part of the 380-425Ma Galway Granite Complex in western Ireland. Molybdenite mineralisation within the Galway Granite Complex occurred in close association with protracted magmatism at 423Ma, 410Ma, 407Ma, 397Ma and 383Ma and this continues to be of interest to active exploration. The aim of the project is to characterize hydrothermal alteration associated with Mo-Cu mineralisation and identify geochemical indicators that can guide future exploration work. The Murvey Granite intrudes metagabbros and gneiss that form part of the Connemara Metamorphic complex. The intrusion is composed of albite-rich pink granite, garnetiferous granite and phenocrytic orthoclase granite. Minor doleritic dykes post-date the Murvey Granite, found commonly along its margins. Field mapping shows that the granite is truncated to the east by a regional NW-SE fault and that several small subparallel structures host Mo-Cu bearing quartz veins. Petrographic observations show heavily sericitized feldspars and plagioclase and biotite which have undergone kaolinization and chloritisation. Chalcopyrite minerals are fine grained, heavily fractured found crystallized along the margins of the feldspars and 2mm pyrite crystals. Molybdenite are also seen along the margins of the feldspars, crystallized whilst the Murvey Granite cooled. Field and petrographic observations indicate that mineralisation is structurally controlled by NW-SE faults from the selected mineralization zones and conjugate NE-SW cross cutting the Murvey Granite. Both fault orientations exhibit quartz and disseminated molybdenite

  11. Geochemical Data for Samples Collected in 2007 Near the Concealed Pebble Porphyry Cu-Au-Mo Deposit, Southwest Alaska

    USGS Publications Warehouse

    Fey, David L.; Granitto, Matthew; Giles, Stuart A.; Smith, Steven M.; Eppinger, Robert G.; Kelley, Karen D.

    2008-01-01

    In the summer of 2007, the U.S. Geological Survey (USGS) began an exploration geochemical research study over the Pebble porphyry copper-gold-molydenum (Cu-Au-Mo) deposit in southwest Alaska. The Pebble deposit is extremely large and is almost entirely concealed by tundra, glacial deposits, and post-Cretaceous volcanic and volcaniclastic rocks. The deposit is presently being explored by Northern Dynasty Minerals, Ltd., and Anglo-American LLC. The USGS undertakes unbiased, broad-scale mineral resource assessments of government lands to provide Congress and citizens with information on national mineral endowment. Research on known deposits is also done to refine and better constrain methods and deposit models for the mineral resource assessments. The Pebble deposit was chosen for this study because it is concealed by surficial cover rocks, it is relatively undisturbed (except for exploration company drill holes), it is a large mineral system, and it is fairly well constrained at depth by the drill hole geology and geochemistry. The goals of the USGS study are (1) to determine whether the concealed deposit can be detected with surface samples, (2) to better understand the processes of metal migration from the deposit to the surface, and (3) to test and develop methods for assessing mineral resources in similar concealed terrains. This report presents analytical results for geochemical samples collected in 2007 from the Pebble deposit and surrounding environs. The analytical data are presented digitally both as an integrated Microsoft 2003 Access? database and as Microsoft 2003 Excel? files. The Pebble deposit is located in southwestern Alaska on state lands about 30 km (18 mi) northwest of the village of Illiamna and 320 km (200 mi) southwest of Anchorage (fig. 1). Elevations in the Pebble area range from 287 m (940 ft) at Frying Pan Lake just south of the deposit to 1146 m (3760 ft) on Kaskanak Mountain about 5 km (5 mi) to the west. The deposit is in an area of

  12. A comparative study of stream water and stream sediment as geochemical exploration media in the Rio Tanama porphyry copper district, Puerto Rico

    USGS Publications Warehouse

    Learned, R.E.; Chao, T.T.; Sanzolone, R.F.

    1985-01-01

    To test the relative effectiveness of stream water and sediment as geochemical exploration media in the Rio Tanama porphyry copper district of Puerto Rico, we collected and subsequently analyzed samples of water and sediment from 29 sites in the rivers and tributaries of the district. Copper, Mo, Pb, Zn, SO42-, and pH were determined in the waters; Cu, Mo, Pb, and Zn were determined in the sediments. In addition, copper in five partial extractions from the sediments was determined. Geochemical contrast (anomaly-to-background quotient) was the principal criterion by which the effectiveness of the two media and the five extractions were judged. Among the distribution patterns of metals in stream water, that of copper most clearly delineates the known porphyry copper deposits and yields the longest discernable dispersion train. The distribution patterns of Mo, Pb, and Zn in water show little relationship to the known mineralization. The distribution of SO42- in water delineates the copper deposits and also the more extensive pyrite alteration in the district; its recognizable downstream dispersion train is substantially longer than those of the metals, either in water or sediment. Low pH values in small tributaries delineate areas of known sulfide mineralization. The distribution patterns of copper in sediments clearly delineate the known deposits, and the dispersion trains are longer than those of copper in water. The partial determinations of copper related to secondary iron and manganese oxides yield the strongest geochemical contrasts and longest recognizable dispersion trains. Significantly high concentrations of molybdenum in sediments were found at only three sites, all within one-half km downstream of the known copper deposits. The distribution patterns of lead and zinc in sediments are clearly related to the known primary lead-zinc haloes around the copper deposits. The recognizable downstream dispersion trains of lead and zinc are shorter than those of

  13. Laramide alteration of proterozoic diabase: A likely contributor of copper to porphyry systems in the dripping spring mountains area, Southeastern Arizona

    USGS Publications Warehouse

    Force, E.R.

    1998-01-01

    Proterozoic diabase of the Dripping Spring range occurs as sills in the Proterozoic Apache Group and the Troy Quartzite and as intrusive sheets in basement rocks. The aggregate thickness of the diabase sills and intrusive sheets averages about 450 m in the part of the range showing little mid-Tertiary extension. Laramide alteration is of two types, dominated by chlorite and actinolite, respectively, and formed mostly from clinopyroxene. Actinolite-dominated assemblages are higher in Na and Ca. Hydrothermal biotite is common in the central areas of both alteration types. Laramide alteration forms two distribution patterns: a subequant pattern centered on Laramide intrusions and small porphyry deposits, characterized by actinolitic alteration, and a more extensive branching linear pattern that follows Laramide structures, centered on the larger Ray porphyry deposit, extending toward other Laramide districts and showing both alteration types. Alteration has apparently mobilized copper and other metals from diabase. The freshest diabase samples average about 120 ppm copper with little variation. In chloritic alteration, about 100 ppm of this copper is expelled in the most completely altered rocks. In actinolitic alteration, diabase may either gain or lose copper during alteration. Chloritic alteration constitutes roughly 70 percent of the diabase alteration in the study area, where alteration averages 41 percent complete. This implies liberation of about 9 ?? 106 tons (t) copper from diabase alteration, significantly less than the 16 ?? 106 t copper in Laramide mineral deposits of the superdistrict (Ray, Superior, Chilito, Christmas). However, diabase alteration may have been a significant component of the supply of copper to the Laramide mineral districts of the area. Synmineral magmatic sources of copper are not documented in this area. The distribution of Proterozoic diabase coincides with the central part of the southeastern Arizona copper province, which may thus

  14. Three-dimensional distribution of igneous rocks near the Pebble porphyry Cu-Au-Mo deposit in southwestern Alaska: constraints from regional-scale aeromagnetic data

    USGS Publications Warehouse

    Anderson, Eric D.; Zhou, Wei; Li, Yaoguo; Hitzman, Murray W.; Monecke, Thomas; Lang, James R.; Kelley, Karen D.

    2014-01-01

    Aeromagnetic data helped us to understand the 3D distribution of plutonic rocks near the Pebble porphyry copper deposit in southwestern Alaska, USA. Magnetic susceptibility measurements showed that rocks in the Pebble district are more magnetic than rocks of comparable compositions in the Pike Creek–Stuyahok Hills volcano-plutonic complex. The reduced-to-pole transformation of the aeromagnetic data demonstrated that the older rocks in the Pebble district produce strong magnetic anomaly highs. The tilt derivative transformation highlighted northeast-trending lineaments attributed to Tertiary volcanic rocks. Multiscale edge detection delineated near-surface magnetic sources that are mostly outward dipping and coalesce at depth in the Pebble district. The total horizontal gradient of the 10-km upward-continued magnetic data showed an oval, deep magnetic contact along which porphyry deposits occur. Forward and inverse magnetic modeling showed that the magnetic rocks in the Pebble district extend to depths greater than 9 km. Magnetic inversion was constrained by a near-surface, 3D geologic model that is attributed with measured magnetic susceptibilities from various rock types in the region. The inversion results indicated that several near-surface magnetic sources with moderate susceptibilities converge with depth into magnetic bodies with higher susceptibilities. This deep magnetic source appeared to rise toward the surface in several areas. An isosurface value of 0.02 SI was used to depict the magnetic contact between outcropping granodiorite and nonmagnetic sedimentary host rocks. The contact was shown to be outward dipping. At depths around 5 km, nearly the entire model exceeded the isosurface value indicating the limits of nonmagnetic host material. The inversion results showed the presence of a relatively deep, northeast-trending magnetic low that parallels lineaments mapped by the tilt derivative. This deep low represents a strand of the Lake Clark fault.

  15. Trace element and isotope (Sr, Nd) geochemistry of porphyry- and skarn-mineralising Late Cretaceous intrusions from Banat, western South Carpathians, Romania

    NASA Astrophysics Data System (ADS)

    Dupont, Alain; Vander Auwera, Jacqueline; Pin, Christian; Marincea, Ştefan; Berza, Tudor

    2002-08-01

    Geochemical and isotopic (strontium, neodymium) data have been obtained from 24 samples of seven Late Cretaceous intrusions associated with skarn (Tincova, Bocşa, Ocna de Fier - Dognecea) and porphyry copper-molybdenum/skarn deposits (Oraviţa, Ciclova, Sasca and Moldova Nouă) in the South Carpathians of Romania. The intrusions cut the Supragetic-Getic nappes and form a 100-km-long, NNE-SSW-trending lineament in the Banat metallogenic province. The samples range in composition from gabbro to granodiorite and define, in major and trace element variation diagrams, a calc-alkaline to high-potassium calc-alkaline trend ranging from 50 to 67% SiO2. They are magnetite-bearing, I-type granitoids enriched in LILE/LREE and depleted in Nb, Ta and Zr, common features for magmas associated with subduction zones. The lack of cumulate textures and of positive europium anomalies seems to indicate that the samples represent liquid compositions. The observed trend thus approximates a liquid line of descent resulting from fractional crystallisation of parental magmas with similar major and trace element compositions. Initial strontium isotopic ratios (Sri) vary from 0.7042 to 0.7058 and ɛNd(t) values range from +3.9 to -0.2. Variations of Sri and ɛNd(t) values with SiO2 show minor crustal assimilation. The generally positive ɛNd(t) values, together with moderate Sri, indicate that the parental magmas result from partial melting of a rubidium-enriched and LREE-depleted source, such as a heterogeneous lithospheric mantle or a young mafic lower crust derived from it. Selective rubidium enrichment probably occurred during a previous subduction event by metasomatism of the overlying mantle wedge, either in the Early Cretaceous or earlier, as suggested by TDM model ages (ca. 600 Ma). The Cu-Mo(-Pb-Zn-Fe) deposits are intimately associated with the intrusions, and the Banat (Romania) region can be subdivided in two metallogenic zones. In northern Banat, Fe-Cu-Pb-Zn skarns occur

  16. Geochronology and fluid inclusion study of the Yinjiagou porphyry-skarn Mo-Cu-pyrite deposit in the East Qinling orogenic belt, China

    NASA Astrophysics Data System (ADS)

    Wu, Guang; Chen, Yuchuan; Li, Zongyan; Liu, Jun; Yang, Xinsheng; Qiao, Cuijie

    2014-01-01

    The Yinjiagou Mo-Cu-pyrite deposit of Henan Province is located in the Huaxiong block on the southern margin of the North China craton. It differs from other Mo deposits in the East Qingling area because of its large pyrite resource and complex associated elements. The deposit's mineralization process can be divided into skarn, sulfide, and supergene episodes with five stages, marking formation of magnetite in the skarn episode, quartz-molybdenite, quartz-calcite-pyrite-chalcopyrite-bornite-sphalerite, and calcite-galena-sphalerite in the sulfide episode, and chalcedony-limonite in the supergene episode. Re-Os and 40Ar-39Ar dating indicates that both the skarn-type and porphyry-type orebodies of the Yinjiagou deposit formed approximately 143 Ma ago during the Early Cretaceous. Four types of fluid inclusions (FIs) have been distinguished in quartz phenocryst, various quartz veins, and calcite vein. Based on petrographic observations and microthermometric criteria the FIs include liquid-rich, gas-rich, H2O-CO2, and daughter mineral-bearing inclusions. The homogenization temperature of FIs in quartz phenocrysts of K-feldspar granite porphyry ranges from 341 °C to >550 °C, and the salinity is 0.4-44.0 wt% NaCl eqv. The homogenization temperature of FIs in quartz-molybdenite veins is 382-416 °C, and the salinity is 3.6-40.8 wt% NaCl eqv. The homogenization temperature of FIs in quartz-calcite-pyrite-chalcopyrite-bornite-sphalerite ranges from 318 °C to 436 °C, and the salinity is 5.6-42.4 wt% NaCl eqv. The homogenization temperature of FIs in quartz-molybdenite stockworks is in a range of 321-411 °C, and the salinity is 6.3-16.4 wt% NaCl eqv. The homogenization temperature of FIs in quartz-sericite-pyrite is in a range of 326-419 °C, and the salinity is 4.7-49.4 wt% NaCl eqv. The ore-forming fluids of the Yinjiagou deposit are mainly high-temperature, high-salinity fluids, generally with affinities to an H2O-NaCl-KCl ± CO2 system. The δ18OH2O values of ore

  17. Refinement of the time-space evolution of the giant Mio-Pliocene Río Blanco-Los Bronces porphyry Cu-Mo cluster, Central Chile: new U-Pb (SHRIMP II) and Re-Os geochronology and 40Ar/39Ar thermochronology data

    NASA Astrophysics Data System (ADS)

    Deckart, Katja; Clark, Alan H.; Cuadra, Patricio; Fanning, Mark

    2013-01-01

    Representing one of the largest known (estimated >5 Gt at 1 % Cu and 0.02 % Mo) porphyry system, the Río Blanco-Los Bronces deposit incorporates at least five hypabyssal intrusive and hydrothermal centres, extending for about 5 km from the Río Blanco and Los Bronces mines in the north, through the Don Luis mine, to the Sur Sur mine, La Americana and Los Sulfatos in the south. The new geochronology data, which now include data on different molybdenite vein types, confirm the U-Pb ages of the pre-mineralisation intrusions but slightly increase their age range from 8.8 to 8.2 Ma. The distinct magmatic pulses of the mineralisation-associated porphyritic intrusives (Late Porphyries) indicate an age interval instead of the previously suggested individual ages: the quartz monzonite porphyry ranges from 7.7 to 6.1 Ma (Sur Sur 5.74 ± 0.13 Ma), the feldspar porphyry shows an interval from 5.8 to 5.2 Ma and the Don Luis porphyry from 5.2 to 5.0 Ma. The new Re-Os data on distinct molybdenite vein types confirm the protracted history of Cu(-Mo) mineralisation, inferred previously. The vein development occurred at least from 5.94 to 4.50 Ma, indicating a time-span of 1.5 Ma for the hydrothermal activity. Hydrothermal minerals dated by the 40Ar/39Ar method are generally too young to record the age of early, high-temperature mineralisation. The majority of the 40Ar/39Ar data in the Río Blanco porphyry cluster record reheating by either the youngest member of the Late Porphyry suite or the post-mineralisation dacite or rhyolite plug formations at around 4.9-4.7 Ma.

  18. Exploration case study using indicator minerals in till at the giant Pebble porphyry Cu-Au-Mo deposit, southwest Alaska, USA

    USGS Publications Warehouse

    Eppinger, Robert G.; Kelley, Karen D.; Fey, David L.; Giles, Stuart A.; Smith, Steven G.

    2011-01-01

    The Pebble deposit in southwest Alaska (Fig. 1) contains one of the largest resources of copper and gold in the world. It includes a measured and indicated resource of 5,942 million tonnes (Mt) at 0.42% Cu, 0.35 g/t Au, and 250 ppm Mo (0.30% copper equivalent, CuEQ, cut off) and contains significant concentrations of Ag, Pd, and Re (Northern Dynasty Minerals 2011). The deposit remains open at depth. The Pebble West zone was discovered in 1989 by Cominco American. In 2005, Northern Dynasty Minerals Ltd. (NDM) discovered Pebble East, and in July 2007, NDM partnered with Anglo American to form the Pebble Limited Partnership (PLP). The U.S. Geological Survey began collaborative investigations with PLP in 2007 to identify techniques that will improve mineral exploration in covered terranes. The Pebble deposit is an ideal location for such a study because the deposit is undisturbed (except for drilling), is almost entirely concealed by post-mineral volcanic rocks and glacial deposits, and because its distribution is well constrained in the subsurface by PLP’s drill-hole geology and geochemistry. An exploration method developed by Averill (2007) that utilizes porphyry copper indicator minerals (PCIMR) in glacial till samples was applied at Pebble; samples were collected up- and down-ice (of former glaciers) from the deposit. The distribution of several PCIMs identifies the deposit, which suggests that PCIMs may be useful in exploration for other concealed porphyry deposits in the region. In this study, we compare the efficacy of PCIMs relative to that of pond and stream sediments also collected in the deposit area. The Pebble deposit is located 380 km southwest of Anchorage, in the Bristol Bay region of southwest Alaska. There is no road network and access to the study area is by helicopter. The deposit is situated in a broad glacially sculpted topographic low at the head of three drainages, Talarik Creek, North Fork Koktuli River, and the South Fork Koktuli River (Fig

  19. Early Carboniferous adakitic rocks in the area of the Tuwu deposit, eastern Tianshan, NW China: Slab melting and implications for porphyry copper mineralization

    NASA Astrophysics Data System (ADS)

    Wang, Yin-Hong; Xue, Chun-Ji; Liu, Jia-Jun; Wang, Jian-Ping; Yang, Jun-Tao; Zhang, Fang-Fang; Zhao, Ze-Nan; Zhao, Yun-Jiang; Liu, Bin

    2015-05-01

    Existing geochronological and geochemical data for the Early Carboniferous magmatic rocks in the eastern Tianshan, Xinjiang, have been interpreted in a variety of theories regarding petrogenesis and geodynamic setting. The proposed settings include rift, back-arc basin, passive continental margin, island arc, ridge subduction, and post-collisional environment. To evaluate these possibilities, we present new SHRIMP zircon U-Pb geochronology and geochemical data, whole-rock geochemical, Hf isotope, and S isotope data for tonalitic rocks and ores associated with the Tuwu porphyry copper deposit located in the center of the late Paleozoic Dananhu-Tousuquan arc, eastern Tianshan. SHRIMP zircon U-Pb dating indicates that the magmatic activity and thus associated copper mineralization occurred ca.332 Ma. The tonalitic rocks are calc-alkaline granites with A/CNK values ranging from 1.16 to 1.58; are enriched in K, Rb, Sr, and Ba; and are markedly depleted in Nb, Ta, Ti, and Th. They show geochemical affinities similar to adakites, with high Sr, Al2O3, and Na2O contents and La/Yb ratios; low Y and Yb contents; and slight positive Eu anomalies. In situ Hf isotopic analyses of zircons yielded positive initial εHf(t) values ranging from 6.9 to 17.2. The δ34S values of the ore sulfides range from -3.0‰ to +1.7‰, reflecting a deep sulfur source. Our results indicate that the paleo-Tianshan oceanic slab was being simultaneously subducted northward beneath the Dananhu-Tousuquan arc, and southward beneath the Aqishan-Yamansu arc during the Early Carboniferous. The Tuwu adakitic tonalitic rocks were derived from the partial melting of the subducted paleo-Tianshan oceanic slab, which was subsequently hybridized by mantle wedge peridotites. The slab-derived magmas have considerably high copper contents and are highly oxidized, thus leading to porphyry copper mineralization. Such Early Carboniferous tonalitic rocks that are widespread in the eastern Tianshan define a province

  20. Temporal and spatial distribution of alteration, mineralization and fluid inclusions in the transitional high-sulfidation epithermal-porphyry copper system at Red Mountain, Arizona

    USGS Publications Warehouse

    Lecumberri-Sanchez, Pilar; Newton, M. Claiborne; Westman, Erik C.; Kamilli, Robert J.; Canby, Vertrees M.; Bodnar, Robert J.

    2013-01-01

    Red Mountain, Arizona, is a Laramide porphyry Cu system (PCD) that has experienced only a modest level of erosion compared to most other similar deposits in the southwestern United States. As a result, the upper portion of the magmatic–hydrothermal system, which represents the transition from shallower high-sulfidation epithermal mineralization to deeper porphyry Cu mineralization, is well preserved. Within the Red Mountain system, alteration, mineralization and fluid inclusion assemblages show a systematic distribution in both time and space. Early-potassic alteration (characterized by the minerals biotite and magnetite) is paragenetically earlier than late-potassic alteration (K-feldspar–anhydrite) and both are followed by later phyllic (sericite–pyrite) alteration. Advanced argillic alteration (pyrophyllite–alunite–other clay minerals) is thought to be coeval with or postdate phyllic alteration. Minerals characteristic of advanced argillic alteration are present in the near surface. Phyllic alteration extends to greater depths compared to advanced argillic alteration. Early-potassic and late-potassic alteration are only observed in the deepest part of the system. Considerable overlap of phyllic alteration with both early-potassic and late-potassic alteration zones is observed. The hypogene mineralization contains 0.4–1.2% Cu and is spatially and temporally related to the late-potassic alteration event. Molybdenum concentration is typically In the deepest part of the system, an early generation of low-to-moderate density and salinity liquid + vapor inclusions with opaque daughter minerals is followed in time by halite-bearing inclusions that also contain opaque daughter minerals indicating that an early intermediate-density magmatic fluid evolved to a high-density, high-salinity mineralizing fluid. The increase in density and salinity of fluids with time observed in the deeper parts of the system may be the result of immiscibility (“boiling”) of

  1. SEM-Cathodoluminescence and fluid inclusion study of quartz veins in Hugo Dummett porphyry Cu-Au deposit,South Mongolia

    NASA Astrophysics Data System (ADS)

    Sanjaa, M.; Fujimaki, H.; Ken-Ichiro, H.

    2010-12-01

    The Hugo Dummett porphyry copper-gold deposit in Oyu Tolgoi, South Mongolia is a high-sulfidation type deposit which consists of Cu-Au bearing quartz veins. Cathodoluminescence (CL) analysis using scanning electron microscope (SEM) and fluid inclusion microthermometer were performed to elucidate the relationship between CL structures, fluid inclusion microthermometer of different quartz generations, and ore forming process of the Hugo Dummett deposit. Hydrothermal quartz from quartz-sulfide veins in the porphyry Cu-Au deposit in Hugo Dummett, revealing the following textures: (1) euhedral growth zones (2) embayed and rounded CL-bright cores, with CL-dark and CL-gray overgrowths, (3) concentric and non concentric growth zones, and (4) CL dark/bright microfractures. These textures indicate that many veins have undergone fracturing, growth of quartz into fluid-filled space and quartz dissolution of quartz. SEM-CL imaging indicates vein quartz in the Hugo Dummett deposit, initially grew as individual CL-bright crystals 356 ± 10°C liquid-reservoir (average Th value for fluid inclusions in the crystal cores is 359°C). In contract, SEM-CL imaging shows the edges of the micron-scale growth zones of varying CL intensity, reflecting quartz precipitation at some later time, when the Hugo Dummett deposit hydrothermal system had cooled, when reservoir conditions were about 211 ± 25°C (average Th value of 212°C). Crystal growth is SEM-CL evidence of the vein quartz having been partly dissolved. Pressure change has a large effect on quartz solubility and may have been responsible for quartz dissolution and precipitation textures in the cooling hydrothermal system. CL-dark microfractures homogenization temperatures lower 169 ± 16°C (average Th value 170°C) than CL bright and CL gray. Temperature and pressure of the mineralized fluid estimates a pressure of formation of 0.3-0.5 kbar (lithostatic), was formed at approximately 2 km depth, as well as a formation temperature

  2. Naturally acidic surface and ground waters draining porphyry-related mineralized areas of the Southern Rocky Mountains, Colorado and New Mexico

    USGS Publications Warehouse

    Verplanck, P.L.; Nordstrom, D.K.; Bove, D.J.; Plumlee, G.S.; Runkel, R.L.

    2009-01-01

    Acidic, metal-rich waters produced by the oxidative weathering and resulting leaching of major and trace elements from pyritic rocks can adversely affect water quality in receiving streams and riparian ecosystems. Five study areas in the southern Rocky Mountains with naturally acidic waters associated with porphyry mineralization were studied to document variations in water chemistry and processes that control the chemical variations. Study areas include the Upper Animas River watershed, East Alpine Gulch, Mount Emmons, and Handcart Gulch in Colorado and the Red River in New Mexico. Although host-rock lithologies in all these areas range from Precambrian gneisses to Cretaceous sedimentary units to Tertiary volcanic complexes, the mineralization is Tertiary in age and associated with intermediate to felsic composition, porphyritic plutons. Pyrite is ubiquitous, ranging from ???1 to >5 vol.%. Springs and headwater streams have pH values as low as 2.6, SO4 up to 3700 mg/L and high dissolved metal concentrations (for example: Fe up to 400 mg/L; Cu up to 3.5 mg/L; and Zn up to 14.4 mg/L). Intensity of hydrothermal alteration and presence of sulfides are the primary controls of water chemistry of these naturally acidic waters. Subbasins underlain by intensely hydrothermally altered lithologies are poorly vegetated and quite susceptible to storm-induced surface runoff. Within the Red River study area, results from a storm runoff study documented downstream changes in river chemistry: pH decreased from 7.80 to 4.83, alkalinity decreased from 49.4 to <1 mg/L, SO4 increased from 162 to 314 mg/L, dissolved Fe increased from to 0.011 to 0.596 mg/L, and dissolved Zn increased from 0.056 to 0.607 mg/L. Compared to mine drainage in the same study areas, the chemistry of naturally acidic waters tends to overlap but not reach the extreme concentrations of metals and acidity as some mine waters. The chemistry of waters draining these mineralized but unmined areas can be used to

  3. Zircon U-Pb ages, Hf-O isotopes and trace elements of Mesozoic high Sr/Y porphyries from Ningzhen, eastern China: Constraints on their petrogenesis, tectonic implications and Cu mineralization

    NASA Astrophysics Data System (ADS)

    Wang, Fangyue; Liu, Sheng-Ao; Li, Shuguang; Akhtar, Shamim; He, Yongsheng

    2014-07-01

    The relationship between high Sr/Y (adakitic) rocks and Cu mineralization has been long recognized but the mechanism remains unclear. The Cretaceous high Sr/Y porphyries in the Ningzhen area host major Cu polymetallic deposits in the Lower Yangtze River Belt (LYRB) of eastern China. These rocks exhibit some geochemical characteristics (e.g., non-radiogenic Pb isotope ratios) that differ from adakitic rocks from adjacent locations in the LYRB. In this study, we present a study of the zircon U-Pb-Hf-O isotope and trace element compositions for five porphyries from Ningzhen to reveal their petrogenesis and how that correlates with Cu-Fe-Mo mineralization. Zircon U-Pb ages of Anjishan (Cu deposit), Tongshan (Cu-Mo deposit) and Xiangshan (Fe deposit) plutons in the Ningzhen area are 108.8 ± 1.5 Ma, 105-107 Ma and 100-105 Ma, respectively, which are significantly younger than the ore-bearing adakites (140 ± 5 Ma) in the western part of the LYRB. Zircon εHf(t) and δ18O values range from - 23.4 to - 10.6 and from 5.7 to 7.0‰, respectively, falling between subduction-related adakites from the other regions in the LYRB and delamination-related adakitic rocks from the adjacent South Tan-Lu Fault Zone. The similarities of Ce4 +/Ce3 + and Eu/Eu* ratios in zircons from Ningzhen and those from the western LYRB indicate higher oxygen fugacity in their magma sources. Ti-in-zircon thermometer yields magma temperatures of 550 to 700 °C (with an average of ~ 650 °C) for the Ningzhen porphyries, which are significantly lower than those of the South Tan-Lu Fault adakites (> 750 °C), but similar to those for the LYRB adakites (< 700 °C). In summary, the Ningzhen high Sr/Y porphyries have high Mg# (> 50), non-radiogenic Pb, enriched Sr-Nd isotopic compositions, negative zircon εHf(t), mantle-like δ18O values, high oxygen fugacities and low magma temperatures. Mafic rocks that co-exist with ore-bearing porphyries or occur as xenoliths in porphyries are widespread. We proposed

  4. Partial melting of subducted paleo-Pacific plate during the early Cretaceous: Constraint from adakitic rocks in the Shaxi porphyry Cu-Au deposit, Lower Yangtze River Belt

    NASA Astrophysics Data System (ADS)

    Deng, Jianghong; Yang, Xiaoyong; Li, Shuang; Gu, Huangling; Mastoi, Abdul Shakoor; Sun, Weidong

    2016-10-01

    A large porphyry Cu-Au deposit associated with early Cretaceous intrusive rocks has been discovered and explored in the Shaxi area, Lower Yangtze River Belt (LYRB), eastern China. We studied two types of intrusive rocks in the Shaxi area: Cu-Au mineralization related diorites and quartz-diorites (adakitic rocks), and newly found high Sr/Y ratio biotite-gabbros. They were formed almost simultaneously with crystallization ages of ca. 130 to 129 Ma, younger than the early stage shoshonitic rocks (Longmenyuan, Zhuanqiao and Shuangmiao Fm.) in the Luzong volcanic basin, 10 km south of the Shaxi area. These intrusive rocks show similar distribution patterns of trace elements (enriched in LILEs and depleted in HFSEs) and REEs (enriched in LREEs and depleted in HREEs, no Eu negative anomaly, flat HREE patterns). The diorites and quartz-diorites are adakitic rocks with calc-alkaline affinity, distinguished from other adakitic rocks in the LYRB which are high-K calc-alkaline series. The biotite-gabbros are not adakitic rocks, although they are characterized by high Sr/Y ratios.

  5. Significance of SHRIMP U-Pb dating of the Imperial Porphyry and associated Dokhan Volcanics, Gebel Dokhan, north Eastern Desert, Egypt

    NASA Astrophysics Data System (ADS)

    Wilde, S. A.; Youssef, K.

    2000-08-01

    SHRIMP U-Pb zircon dating was undertaken on two samples of Dokhan Volcanics from the type area at Gebel Dokhan, north Eastern Desert, Egypt. A quartz andesite from the Imperial Porphyry unit has a weighted 206Pb/238U age of 593 ± 13 Ma (2σ). A sample of grey andesite, from ~450 m lower in the succession, has a weighted 206Pb/238U age of 602 ± 9 Ma (2σ). These ages are interpreted to record the time of eruption of the Dokhan Volcanics. Two concordant zircon cores in the upper sample define a weighted 206Pb/238U age of 685 ± 16 Ma (2σ), indicating inheritance from an older source. These cores have oscillatory zoning and may be derived from the 'older' granite basement or even an earlier volcanic sequence in the area. Care should, therefore, be taken in correlating all volcanic rocks in the Eastern Desert of Egypt with the Dokhan Volcanic Formation, as defined at the type locality.

  6. Application of fuzzy logic and fuzzy AHP to mineral prospectivity mapping of porphyry and hydrothermal vein copper deposits in the Dananhu-Tousuquan island arc, Xinjiang, NW China

    NASA Astrophysics Data System (ADS)

    Zhang, Nannan; Zhou, Kefa; Du, Xishihui

    2017-04-01

    Mineral prospectivity mapping (MPM) is a multi-step process that ranks promising target areas for further exploration. Fuzzy logic and fuzzy analytical hierarchy process (AHP) are knowledge-driven MPM approaches. In this study, both approaches were used for data processing, based on which MPM was performed for porphyry and hydrothermal vein copper deposits in the Dananhu-Tousuquan island arc, Xinjiang. The results of the two methods were then compared. The two methods combined expert experience and the Studentized contrast (S(C)) values of the weights-of-evidence approach to calculate the weights of 15 layers, and these layers were then integrated by the gamma operator (γ). Through prediction-area (P-A) plot analysis, the optimal γ for fuzzy logic and fuzzy AHP was determined as 0.95 and 0.93, respectively. The thresholds corresponding to different levels of metallogenic probability were defined via concentration-area (C-A) fractal analysis. The prediction performances of the two methods were compared on this basis. The results showed that in MPM based on fuzzy logic, the area under the receiver operating characteristic (ROC) curve was 0.806 and 81.48% of the known deposits were predicted, whereas in MPM based on fuzzy AHP, the area under the ROC curve was 0.862 and 92.59% of the known deposits were predicted. Therefore, prediction based on fuzzy AHP is more accurate and can provide directions for future prospecting.

  7. Examination of chloritization of biotite as a tool for reconstructing the physicochemical parameters of mineralization and associated alteration in the Zafarghand porphyry copper system, Ardestan, Central Iran: mineral-chemistry and stable isotope analyses

    NASA Astrophysics Data System (ADS)

    Aminroayaei Yamini, Maryam; Tutti, Faramarz; Aminoroayaei Yamini, Mohammad Reza; Ahmadian, Jamshid; Wan, Bo

    2016-12-01

    The chloritization of biotite and stable isotopes of silicate have been studied for the Zafarghand porphyry copper deposit, Ardestan, Iran. The studied area, in the central part of the Urumieh-Dokhtar magmatic belt, contains porphyry-style Cu mineralization and associated hydrothermal alteration within the Miocene (19-26 Ma, Zircon U-Pb age) granodioritc stock and adjacent andesitic to rhyodacitic volcanic rocks (ca. 56 Ma, zircon U-Pb age). The primary and secondary biotite that formed during potassic alteration in this porphyry and these volcanic host rocks are variably chloritized. Chloritization of biotite pseudomorphically is characterized by an increase in MgO, FeOt, and MnO, with decreasing in SiO2, K2O, and TiO2. Based on the Ti-in-biotite geothermometer of Henry et al. (Am Mineral 90:316-328, 2005) and Al-in-chlorite geothermometer of Cathelineau (Clay Miner 23:417-485, 1988), crystallization temperatures of primary biotite representative of magmatic conditions and later chloritization temperature range from 617° to 675 °C ± 24 °C and 177° to 346 °C, respectively. Calculated isotopic compositions of fluids that chloritized primary and secondary biotite display isotopic compositions of 1.1 to 1.7 per mil for δ18O and -19.9 to -20.5 per mil for δD consistent with meteoric water. Sericite, barren, and A-type-quartz veins from phyllic alteration were produced by mixed magmatic and meteoric water with δ18O values from -2.8 to 2.5 and δD values of ˜ -23 per mil; the narrow range of δD values of the propylitic epidote may be due to a meteoric water with δ18O values from 0.8 to 1.6 and δD values from -14.6 to -16.9 per mil.

  8. Maps showing mineral resource assessment for copper and molybdenum in porphyry and stockwork deposits and for tungsten, iron, gold, copper, and silver in skarn deposits, Dillion 1 degree by 2 degrees Quadrangle, Idaho and Montana

    USGS Publications Warehouse

    Pearson, R.C.; Trautwein, C.M.; Moll, S.H.; Berger, B.R.; Hanna, W.F.; Loen, J.S.; Rowan, L.C.; Ruppel, E.T.; Segal, D.B.

    1992-01-01

    This report is one of several in the series that assess the mineral resources of the Dillon quadrangle. For the purpose of the assessment, mineral deposits· in the quadrangle that are either known or suspected from a knowledge of the geologic setting have been grou~d into 30 deposit types on the basis of mineralogy, commodity, or structural or depositional setting. The emphasis in these assessment reports is on metallic minerals, but some important nonmetallic minerals will also be assessed. Fossil fuels are beyond the scope of this investigation; phosphate and uranium have been investigated previously (Swanson, 1970; Wodzicki andKrason, 1981); and certain nonmetallic. minerals, including bulk commodities such as sand and gravel, are in large supply and thus not considered. The ·mineral resource assessment discussed in this report considers two deposit types: (1) porphyry or stockwork deposits of copper. and molybdenum (referred to generally in this report as porphyry deposits) and (2) skarn deposits of tungsten, iron, gold, copper, and silver. Combining copper and molybenum porphyry deposits into a single deposit type is believed necessary for this purpose· mainly because the two metals are found together in most .deposits in the quadrangle, a geochemical signature unique to each has not been determined, and the significant petrologic characteristics of many associated plutons are not well known, especially characterist~cs of subsurface plutons whose presence is .inferred from geophysical data. In assessing mineral resources,· we have adopted a general philosophy similar to that of Harrison and others (19S6). We attempt to identify those parts of the quadrangle that are favorable for the occurrence of mineral resources. We do not attempt to locate specific exploration targets nor to determine the quantity of reserves or resources present.

  9. LA-ICP-MS mineral chemistry of titanite and the geological implications for exploration of porphyry Cu deposits in the Jinshajiang - Red River alkaline igneous belt, SW China

    NASA Astrophysics Data System (ADS)

    Xu, Leiluo; Bi, Xianwu; Hu, Ruizhong; Tang, Yongyong; Wang, Xinsong; Xu, Yue

    2015-04-01

    The Jinshajiang-Red River alkaline igneous belt in the eastern Indian-Asian collision zone, of southwestern China, hosts abundant, economically important Cu-Mo-Au mineralization of Cenozoic age. Major- and trace-element compositions of titanites from representative Cu-mineralized intrusions determined by LA-ICP-MS show higher values for Fe2O3/Al2O3, ΣREE + Y, LREE/HREE, Ce/Ce*, (Ce/Ce*)/(Eu/Eu*), U, Th, Ta, Nb and Ga, and lower values for Al2O3, CaO, Eu/Eu*, Zr/Hf, Nb/Ta and Sr than those for titanites from barren intrusions. Different ΣREE + Y, LREE/HREE, U, Th, Ta and Nb values of titanites between Cu-mineralized and barren intrusions were controlled mainly by the coexisting melt compositions. However, different Sr concentrations and negative Eu anomalies of titanites between Cu-mineralized and barren intrusions were most probably caused by different degrees of crystallization of feldspar from melts. In addition, different Ga concentrations and positive Ce anomalies of titanites between Cu-mineralized and barren intrusions were most likely caused by different magmatic fO2 conditions. Pronounced compositional differences of titanites between Cu-mineralized and barren intrusions can provide a useful tool to help discriminate between ore-bearing and barren intrusions at an early stage of exploration, and, thus, have a potential application in exploration for porphyry Cu deposits in the Jinshajiang - Red River alkaline igneous belt, and to other areas.

  10. Integrated geophysical imaging of a concealed mineral deposit: a case study of the world-class Pebble porphyry deposit in southwestern Alaska

    USGS Publications Warehouse

    Shah, Anjana K.; Bedrosian, Paul A.; Anderson, Eric D.; Kelley, Karen D.; Lang, James

    2013-01-01

    We combined aeromagnetic, induced polarization, magnetotelluric, and gravity surveys as well as drillhole geologic, alteration, magnetic susceptibility, and density data for exploration and characterization of the Cu-Au-Mo Pebble porphyry deposit. This undeveloped deposit is almost completely concealed by postmineralization sedimentary and volcanic rocks, presenting an exploration challenge. Individual geophysical methods primarily assist regional characterization. Positive chargeability and conductivity anomalies are observed over a broad region surrounding the deposit, likely representing sulfide minerals that accumulated during multiple stages of hydrothermal alteration. The mineralized area occupies only a small part of the chargeability anomaly because sulfide precipitation was not unique to the deposit, and mafic rocks also exhibit strong chargeability. Conductivity anomalies similarly reflect widespread sulfides as well as water-saturated glacial sediments. Mineralogical and magnetic susceptibility data indicate magnetite destruction primarily within the Cu-Au-Mo mineralized area. The magnetic field does not show a corresponding anomaly low but the analytic signal does in areas where the deposit is not covered by postmineralization igneous rocks. The analytic signal shows similar lows over sedimentary rocks outside of the mineralized area, however, and cannot uniquely distinguish the deposit. We find that the intersection of positive chargeability anomalies with analytic signal lows, indicating elevated sulfide concentrations but low magnetite at shallow depths, roughly delineates the deposit where it is covered only by glacial sediments. Neither chargeability highs nor analytic signal lows are present where the deposit is covered by several hundred meters of sedimentary and volcanic rocks, but a 3D resistivity model derived from magnetotelluric data shows a corresponding zone of higher conductivity. Gravity data highlight geologic features within the

  11. Pb-Sr-Nd isotopes in surficial materials at the Pebble Porphyry Cu-Au-Mo Deposit, Southwestern Alaska: can the mineralizing fingerprint be detected through cover?

    USGS Publications Warehouse

    Ayuso, Robert A.; Kelley, Karen D.; Eppinger, Robert G.; Forni, Francesca

    2013-01-01

    The Cretaceous Pebble porphyry Cu-Au-Mo deposit is covered by tundra and glacigenic sediments. Pb-Sr-Nd measurements were done on sediments and soils to establish baseline conditions prior to the onset of mining operations and contribute to the development of exploration methods for concealed base metal deposits of this type. Pebble rocks have a moderate range for 206Pb/204Pb = 18.574 to 18.874, 207Pb/204Pb = 15.484 to 15.526, and 208,Pb/204Pb = 38.053 to 38.266. Mineralized granodiorite shows a modest spread in 87Sr/86Sr (0.704354–0.707621) and 143Nd/144Nd (0.512639–0.512750). Age-corrected (89 Ma) values for the granodiorite yield relatively unradiogenic Pb (e.g., 207Pb/204Pb 87Sr/86Sr, and positive values of ɛNd (1.00–4.52) that attest to a major contribution of mantle-derived source rocks. Pond sediments and soils have similar Pb isotope signatures and 87Sr/86Sr and 143Nd/144Nd values that resemble the mineralized granodiorites. Glacial events have obscured the recognition of isotope signatures of mineralized rocks in the sediments and soils. Baseline radiogenic isotope compositions, prior to the onset of mining operations, reflect natural erosion, transport and deposition of heterogeneous till sheets that included debris from barren rocks, mineralized granodiorite and sulfides from the Pebble deposit, and other country rocks that pre- and postdate the mineralization events. Isotopic variations suggest that natural weathering of the deposit is generally reflected in these surficial materials. The isotope data provide geochemical constraints to glimpse through the extensive cover and together with other geochemical observations provide a vector to concealed mineralized rocks genetically linked with the Pebble deposit.

  12. Temporal evolution of bacterial communities associated with the in situ wetland-based remediation of a marine shore porphyry copper tailings deposit.

    PubMed

    Diaby, N; Dold, B; Rohrbach, E; Holliger, C; Rossi, P

    2015-11-15

    Mine tailings are a serious threat to the environment and public health. Remediation of these residues can be carried out effectively by the activation of specific microbial processes. This article presents detailed information about temporal changes in bacterial community composition during the remediation of a section of porphyry copper tailings deposited on the Bahía de Ite shoreline (Peru). An experimental remediation cell was flooded and transformed into a wetland in order to prevent oxidation processes, immobilizing metals. Initially, the top oxidation zone of the tailings deposit displayed a low pH (3.1) and high concentrations of metals, sulfate, and chloride, in a sandy grain size geological matrix. This habitat was dominated by sulfur- and iron-oxidizing bacteria, such as Leptospirillum spp., Acidithiobacillus spp., and Sulfobacillus spp., in a microbial community which structure resembled acid mine drainage environments. After wetland implementation, the cell was water-saturated, the acidity was consumed and metals dropped to a fraction of their initial respective concentrations. Bacterial communities analyzed by massive sequencing showed time-dependent changes both in composition and cell numbers. The final remediation stage was characterized by the highest bacterial diversity and evenness. Aside from classical sulfate reducers from the phyla δ-Proteobacteria and Firmicutes, community structure comprised taxa derived from very diverse habitats. The community was also characterized by an elevated proportion of rare phyla and unaffiliated sequences. Numerical ecology analysis confirmed that the temporal population evolution was driven by pH, redox, and K. Results of this study demonstrated the usefulness of a detailed follow-up of the remediation process, not only for the elucidation of the communities gradually switching from autotrophic, oxidizing to heterotrophic and reducing living conditions, but also for the long term management of the remediation

  13. Data integration modeling applied to drill hole planning through semi-supervised learning: A case study from the Dalli Cu-Au porphyry deposit in the central Iran

    NASA Astrophysics Data System (ADS)

    Fatehi, Moslem; Asadi, Hooshang H.

    2017-04-01

    In this study, the application of a transductive support vector machine (TSVM), an innovative semi-supervised learning algorithm, has been proposed for mapping the potential drill targets at a detailed exploration stage. The semi-supervised learning method is a hybrid of supervised and unsupervised learning approach that simultaneously uses both training and non-training data to design a classifier. By using the TSVM algorithm, exploration layers at the Dalli porphyry Cu-Au deposit in the central Iran were integrated to locate the boundary of the Cu-Au mineralization for further drilling. By applying this algorithm on the non-training (unlabeled) and limited training (labeled) Dalli exploration data, the study area was classified in two domains of Cu-Au ore and waste. Then, the results were validated by the earlier block models created, using the available borehole and trench data. In addition to TSVM, the support vector machine (SVM) algorithm was also implemented on the study area for comparison. Thirty percent of the labeled exploration data was used to evaluate the performance of these two algorithms. The results revealed 87 percent correct recognition accuracy for the TSVM algorithm and 82 percent for the SVM algorithm. The deepest inclined borehole, recently drilled in the western part of the Dalli deposit, indicated that the boundary of Cu-Au mineralization, as identified by the TSVM algorithm, was only 15 m off from the actual boundary intersected by this borehole. According to the results of the TSVM algorithm, six new boreholes were suggested for further drilling at the Dalli deposit. This study showed that the TSVM algorithm could be a useful tool for enhancing the mineralization zones and consequently, ensuring a more accurate drill hole planning.

  14. Mo-mineralized porphyries are relatively hydrous and differentiated: insights from the Permian-Triassic granitic complex in the Baituyingzi Mo-Cu district, eastern Inner Mongolia, NE China

    NASA Astrophysics Data System (ADS)

    Sun, Yan; Liu, Jianming; Zeng, Qingdong; Wang, Jingbin; Wang, Yuwang; Hu, Ruizhong; Zhou, Lingli; Wu, Guanbin

    2016-12-01

    Mo-Cu mineralization in the Baituyingzi district of eastern Inner Mongolia occurs within a granitic complex. This paper presents and discusses zircon U-Pb ages and whole-rock geochemical and Sr-Nd-Pb isotopic data from the granitic complex as potential indicators for porphyry Mo fertility. The U-Pb ages indicate that five units of the granitic complex were emplaced between 265.2 ± 0.7 and 246.5 ± 1.0 Ma. Constrained by crosscutting dikes, Mo-Cu mineralization was probably related to the Baituyingzi monzogranite porphyry dated at 248.2 ± 0.64 Ma. The intrusions belong to high-K calc-alkaline to shoshonitic series that are characterized by highly fractionated rare earth element (REE) patterns and strong enrichments of large ion lithophile elements, relative to high-field strength elements. Apart from the ˜246-Ma dike that shows negative ɛNd (t) values (-14.9 to -13.1), the intrusions have ɛNd(t) values ranging from -3.9 to 1.0, relatively young depleted mantle model ages (811 to 1183 Ma), 206Pb/204Pb of 18.137-18.335, and 207Pb/204Pb of 15.591-15.625, which are consistent with a juvenile lower crustal origin. Among the intrusions, the ˜248-Ma porphyry and the ˜246-Ma dike show adakite-like characteristics (e.g., Sr/Y = 44.9-185) and listric-shaped REE patterns that indicate amphibole fractionation and a hydrous magma source. However, the porphyry exhibits a higher differentiation index (81.4-91.5) and a steeper REE profile (e.g., LaN/YbN = 25.6-87.0) than those of the ˜246-Ma dike, which suggests that it is highly differentiated. We propose that the complex was generated by the partial melting of juvenile mafic lower crust (containing minor old crustal relicts) that was triggered by collision between the North China Craton and Siberian Craton. As indicated by the Th/Nb, Th/Yb, Ba/Th, and Ba/La ratios of the intrusions, the crust may have been derived from the melting of the fertile mantle wedge that was metasomatized by various amounts of slab-derived fluids

  15. Multimillion year thermal history of a porphyry copper deposit: application of U-Pb, 40Ar/39Ar and (U-Th)/He chronometers, Bajo de la Alumbrera copper-gold deposit, Argentina

    NASA Astrophysics Data System (ADS)

    Harris, Anthony C.; Dunlap, W. James; Reiners, Peter W.; Allen, Charlotte M.; Cooke, David R.; White, Noel C.; Campbell, Ian H.; Golding, Suzanne D.

    2008-03-01

    Application of multiple chronometers (including U-Pb and 40Ar/39Ar geochronology and zircon and apatite (U-Th)/He thermochronology) to porphyry intrusions at the Bajo de la Alumbrera porphyry copper-gold deposit, Argentina, reveals a complex history of reheating that spans millions of years. Previous U-Pb geochronology, combined with our new 40Ar/39Ar data, shows that the multiple porphyritic intrusions at Bajo de la Alumbrera were emplaced during two episodes, the first at about 8.0 Ma (P2 and associated porphyries) and the second about a million years later (Early and Late P3 porphyries). Complex overprinting alteration events have obscured the earliest hydrothermal history of the deposit. By contrast, 40Ar/39Ar data reveal the close temporal relationship of ore-bearing potassic alteration assemblages (7.12 ± 0.13 Ma; biotite) to the emplacement of the P3 intrusions. Consistent with low closure temperatures, younger ages have been determined for associated hydrothermal alkali feldspar (6.82 ± 0.05 Ma and 6.64 ± 0.09 Ma). The temperature-sensitive Ar data also record an unexpected prolonged cooling history (to below 200°C) extending to 5.9 Ma. Our data suggest that the Bajo de la Alumbrera system underwent protracted cooling, after the collapse of the main hydrothermal system, or that one or more low-temperature (~100-200°C) reheating events occurred after emplacement of the porphyritic intrusions at Bajo de la Alumbrera. These have been constrained in part by our new 40Ar/39Ar data (including multidomain diffusion modeling) and (U-Th)/He ages. Single-grain (U-Th)/He ages ( n = 5) for phenocrystic zircon from P2 and P3 intrusive phases bracket these thermal events to between 6.9 (youngest crystallization of intrusion) and 5.1 Ma. Multidomain modeling of alkali feldspar data (from both igneous and hydrothermal crystals) is consistent with the deposit cooling rapidly from magmatic temperatures to below about 300°C, with a more protracted history down to 150

  16. Late Triassic Porphyritic Intrusions And Associated Volcanic Rocks From The Shangri-La Region, Yidun Terrane, Eastern Tibetan Plateau: Implications For Adakitic Magmatism And Porphyry Copper Mineralization

    NASA Astrophysics Data System (ADS)

    Wang, B.; Zhou, M.; Li, J.; Yan, D.

    2011-12-01

    The Yidun terrane, located on the eastern margin of the Tibetan plateau, has been commonly considered to be a Triassic volcanic arc produced by subduction of the Ganzi-Litang oceanic lithosphere. The Yidun terrane is characterized by numerous arc-affinity granitic intrusions located along a 500-km-long, north-south-trending belt. Among these granitic bodies, several small porphyritic intrusions in the southern segment of the terrane (Shangri-La region) are associated with large porphyry copper deposits. These porphyritc intrusions are composed of diorite and quartz diorite, and spatially associated with andesites and dacites. LA-ICP-MS zircon U-Pb ages of the intrusions range from 230 to 215 Ma. The andesites and dacites are intercalated with slates and sandstones and have ages of around 220 Ma. The intrusive and volcanic rocks have SiO2 contents from 56.6 to 67.1 wt.%, Al2O3 from 14.2 to 17.4 wt.% and MgO from 1.9 to 4.2 wt.%. They show significant negative Nb-Ta anomalies on primitive mantle-normalized spidergrams. They have high La/Yb (13-49) ratios with no prominent Eu anomalies. All the rocks have high Sr (258-1980 ppm), and low Y (13-21 ppm) with high Sr/Y ratios (29-102). The geochemical features indicate that both the volcanic rocks and porphyritic intrusions were derived from adakitic magmas. They have similar initial 87Sr/86Sr ratios (0.7058 to 0.7077) and ɛNd (-1.88 to -4.93) values, but can be further divided into two groups: high silica (HSA) and low silica adakitic rocks (LSA). The HSA, representing an early stage of magmatism (230 to 215 Ma), were derived from oceanic slab melts with limited interaction with the overlying mantle wedge. At 215 Ma, more extensive interaction resulted in the formation of LSA. We propose that HSA were produced by flat subduction leading to melting of oceanic slab, whereas subsequent slab break-off caused the significant interaction between slab melts and the mantle wedge and thus the generation of the LSA. Compared with

  17. Rapid transition to long-lived deep crustal magmatic maturation and the formation of giant porphyry-related mineralization (Yanacocha, Peru)

    NASA Astrophysics Data System (ADS)

    Chiaradia, Massimo; Merino, Daniel; Spikings, Richard

    2009-11-01

    needed to understand whether the association of adakite-like magmas with ore, which is typical of other giant porphyry-systems, is the result of the build-up of incompatible volatiles and metals in oxidized magmas that evolve under high-pressure conditions, of recycling of lower crustal sulfide-rich cumulates, and/or of a long-lived, focused transfer of magmas from deep to shallow crustal levels.

  18. Post-collisional magmatism and ore-forming systems in the Menderes massif: new constraints from the Miocene porphyry Mo-Cu Pınarbaşı system, Gediz-Kütahya, western Turkey

    NASA Astrophysics Data System (ADS)

    Delibaş, Okan; Moritz, Robert; Chiaradia, Massimo; Selby, David; Ulianov, Alexey; Revan, Mustafa Kemal

    2017-01-01

    The Pınarbaşı Mo-Cu prospect is hosted within the Pınarbaşı intrusion, which is exposed together with the NW-SE-trending Koyunoba, Eğrigöz, and Baklan plutons along the northeastern border of the Menderes massif. The Pınarbaşı intrusion predominantly comprises monzonite, porphyritic granite, and monzodiorite. All units of the Pınarbaşı intrusion have sharp intrusive contacts with each other. The principal mineralization style at the Pınarbaşı prospect is a porphyry-type Mo-Cu mineralization hosted predominantly by monzonite and porphyritic granite. The porphyry type Mo-Cu mineralization consists mostly of stockwork and NE- and EW-striking sub-vertical quartz veins. Stockwork-type quartz veins hosted by the upper parts of the porphyritic granite within the monzonite, are typically enriched in chalcopyrite, molybdenite, pyrite, and limonite. The late NE- and EW-striking normal faults cut the stockwork vein system and control the quartz-molybdenite-chalcopyrite-sphalerite-fahlore-galena veins, as well as molybdenite-hematite-bearing silicified zones. Lithogeochemical and whole-rock radiogenic isotope data (Sr, Nd and Pb) of the host rocks, together with Re-Os molybdenite ages (18.3 ± 0.1 Ma - 18.2 ± 0.1 Ma) reveal that the monzonitic and granitic rocks of the Pınarbaşı intrusion were derived from an enriched lithospheric mantle-lower crust during Oligo-Miocene post-collisional magmatism. The lithospheric mantle was metasomatised by fluids and subducted sediments, and the mantle-derived melts interacted with lower crust at 35-40 km depth. This mechanism explains the Mo and Cu enrichments of the Pınarbaşı intrusion during back-arc magmatism. We conclude that the melt of the Pınarbaşı intrusion could have rapidly ascended to mid-crustal levels, with only limited crustal assimilation along major trans-lithospheric faults as a result of thinning of the middle to upper crust during regional extension, and resulted in the development of porphyry

  19. Maps showing mineral resource assessment for porphyry and stockwork deposits of copper, molybdenum, and tungsten and for stockwork and disseminated deposits of gold and silver in the Butte 1 degree by 2 degrees Quadrangle, Montana

    USGS Publications Warehouse

    Elliott, J.E.; Moll, S.H.; Wallace, C.A.; Lee, G.K.; Antweiler, J.C.; Lidke, D.J.; Rowan, L.C.; Hanna, W.F.; Trautwein, C.M.; Dwyer, J.L.

    1993-01-01

    This report documents the assessment for potential occurrences of undiscovered porphyry and stockwork deposits of copper, molybdenum, and tungsten (porphyry Cu-Mo-W) and stockwork and disseminated deposits of gold and silver (disseminated Au-Ag) in the Butte 1 °X2° quadrangle. The Butte quadrangle, in west-central Montana, is one of the best known mineral producing regions in the U.S. Mining districts in the quadrangle, including the world famous Butte or Summit Valley district, have produced a variety of metallic and nonmetallic mineral commodities valued at more than $6.4 billion (at the time of production). Because of its importance as a mineral producing region, the Butte quadrangle was selected for study by the U.S. Geological Survey under the Conterminous United States Mineral Assessment Program (CUSMAP). Under this program, new data on geology, geochemistry, geophysics, geochronology, mineral resources, and remote sensing were collected and synthesized. The field and laboratory studies were supported, in part, by funding from the Geologic Framework and Synthesis Program and the Wilderness Program. The methods used in this resource assessment for porphyry Cu-Mo-W and disseminated Au-Ag deposits in the quadrangle include a compilation of all data, the development of descriptive occurrence models, and the analysis of data using techniques provided by a Geographic Information System (GIS). This map is one of several maps on the Butte 1 °X2° quadrangle. Other deposit types have been assessed for the Butte quadrangle, and maps (U.S. Geological Survey (USGS) Miscellaneous Investigation Series Maps) for each of the following have been prepared: Vein and replacement deposits of gold, silver, copper, lead, zinc, manganese, and tungsten (Elliott, Wallace, and others, 1992a) and skarn deposits of gold, silver, copper, tungsten, and iron (Elliott and others, 1992b ). Other publications resulting from this study include linear features map (Rowan and others, 1991

  20. Incorporation of platinum-group elements and cobalt into subsidiary pyrite in alkalic Cu-Au porphyry deposits: significant implications for precious metal distribution in felsic magmatic-hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Hanley, J. J.; MacKenzie, M. K.

    2009-05-01

    Certain alkalic porphyry Cu-Au systems contain significant concentrations of the platinum-group elements (PGE) Pd and Pt, and may serve as important unconventional resources for these metals. Bulk rock analyses of ore styles from these deposits show no correlation between the PGE and Cu-Au abundance, suggesting that the timing/mechanisms of introduction and precipitation for the PGE and Cu-Au were not the same. To elucidate some uncertainties concerning PGE enrichment, we have performed a mineralogical evaluation of two PGE-bearing porphyry systems in British Columbia (the Afton and Mount Milligan deposits) with the aid of a variety of microanalytical techniques (LA-ICPMS, SEM, EMP). Discrete PGE mineralogy in these systems is predominantly represented by Hg-rich Pd-Pt-As-Sb species (naldrettite-stibiopalladinite-sperrylite) and Pd-Te-Hg species (kotulskite-temagamite). However, these mineral phases are unambiguously late- stage (with carbonate-chlorite alteration) and contribute insignificantly (<5-10%) to the total Pd+Pt grade based on mass balance calculations. Similarly, LA-ICPMS analyses of chalcopyrite, bornite, oxides and various common sulfosalts show that these do not contribute any Pd+Pt to the bulk grades. Suprisingly, pyrite is the predominant carrier of PGE. It occurs in trace to minor abundances and predates both the Cu-Au mineralising event and the late stage carbonate-chlorite alteration. LA-ICPMS analyses of pyrite show that at least 90% of the bulk Pd+Pt occurs within this atypical host mineral. The PGE are highly enriched in the cores of the pyrite grains (up to 90 ppm and 20 ppm, respectively) and their abundance correlates well with Co (up to 4 wt%). The rims of the pyrite grains are Co-PGE-poor but Ni-rich. Early Co- PGE enrichment in these deposits may implicate a mafic contributor to the PGE tenor of the deposits, but also a potential crystallographic (substitutional) control on Pd partitioning into pyrite. At Afton, the former is supported

  1. Pre-eruptive conditions of the Hideaway Park topaz rhyolite: Insights into metal source and evolution of magma parental to the Henderson porphyry molybdenum deposit, Colorado

    USGS Publications Warehouse

    Mercer, Celestine N.; Hofstra, Albert H.; Todorov, Todor I.; Roberge, Julie; Burgisser, Alain; Adams, David T.; Cosca, Michael A.

    2015-01-01

    The Hideaway Park tuff is the only preserved extrusive volcanic unit related to the Red Mountain intrusive complex, which produced the world-class Henderson porphyry Mo deposit. Located within the Colorado Mineral Belt, USA, Henderson is the second largest Climax-type Mo deposit in the world, and is therefore an excellent location to investigate magmatic processes leading to Climax-type Mo mineralization. We combine an extensive dataset of major element, volatile, and trace element abundances in quartz-hosted melt inclusions and pumice matrix glass with major element geochemistry from phenocrysts to reconstruct the pre-eruptive conditions and the source and evolution of metals within the magma. Melt inclusions are slightly peraluminous topaz rhyolitic in composition and are volatile-charged (≤6 wt % H2O, ≤600 ppm CO2, ∼0·3–1·0 wt % F, ∼2300–3500 ppm Cl) and metal-rich (∼7–24 ppm Mo, ∼4–14 ppm W, ∼21–52 ppm Pb, ∼28–2700 ppm Zn, <0·1–29 ppm Cu, ∼0·3–1·8 ppm Bi, ∼40–760 ppb Ag, ∼690–1400 ppm Mn). Melt inclusion and pumice matrix glass chemistry reveal that the Hideaway Park magma evolved by large degrees of fractional crystallization (≤60–70%) during quartz crystallization and melt inclusion entrapment at pressures of ≤300 MPa (≤8 km depth), with little to no crystallization upon shallow ascent and eruption. Filter pressing, crystal settling, magma recharge and mixing of less evolved rhyolite melt, and volatile exsolution were important processes during magma evolution; the low estimated viscosities (∼105–1010 Pa s) of these H2O- and F-rich melts probably enhanced these processes. A noteworthy discrepancy between the metal contents in the pumice matrix glass and in the melt inclusions suggests that after quartz crystallization ceased upon shallow magma ascent and eruption, the Hideaway Park magma exsolved an aqueous fluid into which Mo, Bi, Ag, Zn, Mn, Cs, and Y strongly

  2. Ultra-deep oxidation and exotic copper formation at the late pliocene boyongan and bayugo porphyry copper-gold deposits, surigao, philippines: Geology, mineralogy, paleoaltimetry, and their implications for Geologic, physiographic, and tectonic controls

    USGS Publications Warehouse

    Braxton, D.P.; Cooke, D.R.; Ignacio, A.M.; Rye, R.O.; Waters, P.J.

    2009-01-01

    The Boyongan and Bayugo porphyry copper-gold deposits are part of an emerging belt of intrusion-centered gold-rich deposits in the Surigao district of northeast Mindanao, Philippines. Exhumation and weathering of these Late Pliocene-age deposits has led to the development of the world's deepest known porphyry oxidation profile at Boyongan (600 m), and yet only a modest (30-70 m) oxidation profile at adjacent Bayugo. Debris flows, volcanic rocks, and fluviolacustrine sediments accumulating in the actively extending Mainit graben subsequently covered the deposits and preserved the supergene profiles. At Boyongan and Bayugo, there is a vertical transition from shallower supergene copper oxide minerals (malachite + azurite + cuprite) to deeper sulfide-stable assemblages (chalcocite ?? hypogene sulfides). This transition provides a time-integrated proxy for the position of the water table at the base of the saturated zone during supergene oxidation. Contours of the elevation of the paleopotentiometric surface based on this min- eralogical transition show that the thickest portions of the unsaturated zone coincided with a silt-sand matrix diatreme breccia complex at Boyongan. Within the breccia complex, the thickness of the unsaturated zone approached 600 in, whereas outside the breccia complex (e.g., at Bayugo), the thickness averaged 50 m. Contours of the paleopotentiometric surface suggest that during weathering, groundwater flowed into the breccia complex from the north, south, and east, and exited along a high permeability zone to the west. The high relief (>550 m) on the elevation of the paleopotentiometric surface is consistent with an environment of high topographic relief, and the outflow zone to the west of the breccia complex probably reflects proximity to a steep scarp intersecting the western breccia complex margin. Stable isotope paleoaltimetry has enabled estimation of the elevation of the land surface, which further constrains the physiographic setting

  3. Geological, mineralogical and geochemical characteristics of the Radzimowice Au As Cu deposit from the Kaczawa Mountains (Western Sudetes, Poland): an example of the transition of porphyry and epithermal style

    NASA Astrophysics Data System (ADS)

    Mikulski, Stanislaw Z.

    2005-03-01

    The sheeted quartz sulfide veins of the Radzimowice Au As Cu deposit in the Kaczawa Mountains are related to Upper Carboniferous post-collisional potassic magmatism of the composite Zelezniak porphyry intrusion. Multiple intrusive activity ranges from early calc-alkaline to sub-alkaline and alkaline rocks and is followed by multiple hydrothermal events. Early crustally derived dacitic magma has low mg# (<63) and very low concentrations of mantle-compatible trace elements, high large-ion lithophile elements (LILE), moderate light rare-earth elements (LREE), and low high-field-strength elements (HFSE). Later phases of more alkaline rocks have higher mg# (60 70), and LILE, LREE, and HFSE characteristics that indicate mafic magma contributions in a felsic magma chamber. The last episode of the magmatic evolution is represented by lamprophyre dikes which pre-date ore mineralization and are spatially related to quartz sulfide carbonate veins. The dikes consist of kersantite and spessartite of calc-alkaline affinity with K2O/Na2O ratios of 1.1 1.9, mg# of 77 79, and high abundances of mantle-compatible trace elements such as Cr, Ni, and V. They have high LILE, low LREE, and low HFSE contents suggesting a subduction-related post-collisional arc-setting. The mineralization started with arsenopyrite that was strongly brecciated and overprinted by multiple quartz carbonate phases associated with base-metal sulfides and Au Ag Bi Te Pb±S minerals. The sulfur isotope composition of sulfides ranges from -1.1 to 2.8‰ δ34S and suggests a magmatic source. At least two generations of gold deposition are recognized: (1) early refractory, and (2) subsequent non-refractory gold mineralization of epithermal style. Co-rich arsenopyrite with refractory gold and pyrite are the most abundant minerals of the early stage of sulfide precipitation. Early arsenopyrite formed at 535 345°C along the arsenopyrite pyrrhotite loellingite buffer and late arsenopyrite crystallized below 370

  4. Recolonisation of mine tailing by meiofauna in mesocosm and microcosm experiments.

    PubMed

    Gwyther, David; Batterham, Grant J; Waworuntu, Jorina; Gultom, Tonny H; Prayogo, Windy; Susetiono; Karnan

    2009-06-01

    The Batu Hijau copper/gold mine in Sumbawa, Indonesia processes ore at approximately 130,000tpd and discharges tailing via a submarine pipeline to depths below 3000m at the base of a submarine canyon. The study investigated recolonisation of tailing by meiofauna and its dependence on subsequent accumulation of natural sediment. Microcosm and mesocosm scale experiments were carried out using two tailing and two control samples, the latter comprising defaunated and unaffected natural sediment. All test materials were similar in physical and chemical respects, except for the higher copper concentration in the tailing. The abundances of meiofauna colonising defaunated controls and both tailing samples increased from zero to levels statistically indistinguishable from natural unaffected controls after 97 and 203days. Colonisation was well established in tailing from freshly mined ore after 40days, and in oxidized tailing from stockpiled ore after 65days, and was not dependent on settled natural material.

  5. Ecosystem Health in Mineralized Terrane-Data from Podiform Chromite (Chinese Camp Mining District, California), Quartz Alunite (Castle Peak and Masonic Mining Districts, Nevada/California), and Mo/Cu Porphyry (Battle Mountain Mining District, Nevada) Deposits

    USGS Publications Warehouse

    Blecker, Steve W.; Stillings, Lisa L.; Amacher, Michael C.; Ippolito, James A.; DeCrappeo, Nicole M.

    2010-01-01

    various mineralized terranes. We were also interested in examining these relations in the context of determining appropriate reference conditions with which to compare reclamation efforts. The purpose of this report is to present the data used to develop indices of soil and ecosystem quality associated with mineralized terranes (areas enriched in metal-bearing minerals), specifically podiform chromite, quartz alunite, and Mo/Cu porphyry systems. Within each of these mineralized terranes, a nearby unmineralized counterpart was chosen for comparison. The data consist of soil biological, chemical, and physical parameters, along with vegetation measurements for each of the sites described below. Synthesis of these data and index development will be the subject of future publications.

  6. Lead-isotopic, sulphur-isotopic, and trace-element studies of galena from the Silesian-Cracow Zn-Pb ores, polymetallic veins from the Gory Swietokrzyskie MTS, and the Myszkow porphyry copper deposit, Poland

    USGS Publications Warehouse

    Church, S.E.; Vaughn, R.B.; Gent, C.A.; Hopkins, R.T.

    1996-01-01

    Lead-isotopic data on galena samples collected from a paragenetically constrained suite of samples from the Silesian-Cracow ore district show no regional or paragenetically controlled lead-isotopic trends within the analytical reproducibility of the measurements. Furthermore, the new lead-isotopic data agree with previously reported lead-isotopic results (R. E. Zartman et al., 1979). Sulfur-isotopic analyses of ores from the Silesian-Cracow district as well as from vein ore from the Gory Swietokrzyskie Mts. and the Myszkow porphyry copper deposit, when coupled with trace-element data from the galena samples, clearly discriminate different hydrothermal ore-forming events. Lead-isotopic data from the Permian and Miocene evaporite deposits in Poland indicate that neither of these evaporite deposits were a source of metals for the Silesian-Cracow district ores. Furthermore, lead-isotopic data from these evaporite deposits and the shale residues from the Miocene halite samples indicate that the crustal evolution of lead in the central and western European platform in southern Poland followed normal crustal lead-isotopic growth, and that the isotopic composition of crustal lead had progressed beyond the lead-isotopic composition of lead in the Silesian-Cracow ores by Permian time. Thus, Mesozoic and Tertiary sedimentary flysch rocks can be eliminated as viable source rocks for the metals in the Silesian-Cracow Mississippi Valley-type (MVT) deposits. The uniformity of the isotopic composition of lead in the Silesian-Cracow ores, when coupled with the geologic evidence that mineralization must post-date Late Jurassic faulting (E. Gorecka, 1991), constrains the geochemical nature of the source region. The source of the metals is probably a well-mixed, multi-cycle molasse sequence of sedimentary rocks that contains little if any Precambrian metamorphic or granitic clasts (S. E. Church, R. B. Vaughn, 1992). If ore deposition was post Late Jurassic (about 150 m. y.) or later

  7. Integration of Stream Sediment Geochemical and Aster Data for Porphyry Copper Deposit Exploration in Khatun Abad, North West of Iran / Integracja geochemicznych danych o osadach dennych oraz danych pozyskanych z systemu aster do poszukiwań geologicznych w rejonie złóż miedzi porfirytowej w khatun abad, w północno-zachodniej części iranu

    NASA Astrophysics Data System (ADS)

    Honarpazhouh, Jamal; Hassanipak, Ali Asghar; Seifpanahi Shabani, Kumars

    2013-03-01

    Urumieh-Dokhtar magmatic belt is the host of large porphyry copper deposits in Iran. Khatun Abad area is located in north west part of this belt, so in this study, the stream sediment geochemical survey and hydrothermal alteration zones extracted from ASTER data were used to generation new target for future lithogeochemical survey. In this study after a brief discussion on descriptive statistics, principal component analysis (PCA) and hierarchical cluster analysis were used to compress the information to a few maps and to assist in determining multi-element associations. Then C-A fractal method was used for map classification. In order to extraction hydrothermal zones ASTER data were used. ASTER SWIR bands are most useful for the identification of alteration minerals such as Alunite, Pyrophylite, Kaolinite, Sericute and Carbonates. In this paper based on spectral analysis of ASTER SWIR data six maps of alteration zones were prepared. Geochemical study and spectral analysis of ASTER data showed that mineralization and alteration are limited to E1lb and gr lithological units and have NW-SE trends from east of Khatun Abad to Ghezeljeh-Gheshlaghi.

  8. Solid Waste Composition and Quantification at Taman Melewar, Parit Raja, Batu Pahat

    NASA Astrophysics Data System (ADS)

    Kadir, A. A.; Abidin, S. S. S. Z.

    2016-07-01

    The poor management of solid waste is noticeable through the increasing of the solid waste each year and the difficulties in disposing the waste in the current available landfill. This study was undertaken to analyze the quantity and composition of waste generation in Taman melewar. Taman Melewar is a student residential area and this study is focusing on student's daily waste composition. The objective of this study was to identify the amount of solid waste generation, analyze and classify the composition of solid waste in Taman Melewar. The waste collection was conducted for 50 houses on a daily basis for two weeks. The average household waste generation rate was 0.082 kg/person/day. Organic waste was the major constituent of waste production. The average of organic waste represents about 72.4% followed by paper (9%), plastics film (5.5%), plastics rigid (4.7%), napkins (3.8%), tetrapek (1.3%), glass (1.1%), household hazardous waste (0.85%), textiles (0.52%), metal (0.51%) and rubber (0.34%). The moisture content was ranging from 27.67% to 28.68%. An evaluation was made based on student's behavior towards waste production and recycling. In conclusion, the results revealed that organic waste is the highest waste generated and recycling habits is also poor in Taman Melewar.

  9. Drinking Water Quality of Water Vending Machines in Parit Raja, Batu Pahat, Johor

    NASA Astrophysics Data System (ADS)

    Hashim, N. H.; Yusop, H. M.

    2016-07-01

    An increased in demand from the consumer due to their perceptions on tap water quality is identified as one of the major factor on why they are mentally prepared to pay for the price of the better quality drinking water. The thought that filtered water quality including that are commercially available in the market such as mineral and bottled drinking water and from the drinking water vending machine makes they highly confident on the level of hygiene, safety and the mineral content of this type of drinking water. This study was investigated the vended water quality from the drinking water vending machine in eight locations in Parit Raja are in terms of pH, total dissolve solids (TDS), turbidity, mineral content (chromium, arsenic, cadmium, lead and nickel), total organic carbon (TOC), pH, total colony-forming units (CFU) and total coliform. All experiments were conducted in one month duration in triplicate samples for each sampling event. The results indicated the TDS and all heavy metals in eight vended water machines in Parit Raja area were found to be below the Food Act 1983, Regulation 360C (Standard for Packaged Drinking Water and Vended water, 2012) and Malaysian Drinking Water Quality, Ministry of Health 1983. No coliform was presence in any of the vended water samples. pH was found to be slightly excess the limit provided while turbidity was found to be 45 to 95 times more higher than 0.1 NTU as required by the Malaysian Food Act Regulation. The data obtained in this study would suggest the important of routine maintenance and inspection of vended water provider in order to maintain a good quality, hygienic and safety level of vended water.

  10. Solid Waste Composition Study at Taman Universiti, Parit Raja, Batu Pahat

    NASA Astrophysics Data System (ADS)

    Kadir, A. A.; Sani, M. S. A. M.

    2016-07-01

    Solid waste management is recognised as one of the most challenging issues confronted by both the developed and developing countries. The problems rise due to growing population in current years which results in increased generation of waste with various compositions. The aim of this study was to determine the waste compositions at Taman Universiti. Taman Universiti is a mix residential and commercial area which a preferred residential location amongst students and lecturers due to its proximate location to UTHM main campus. The waste collection was carried out for 50 houses on a daily basis. The collection and sorting out method was conducted according to Malaysian Standard MS 2505:2012 and the data was collected and recorded The result showed that the average generation rate of household waste at Taman Universiti was 0.16kg/person/day and the moisture content was approximately ranging from 61%-68%. Household wastes collected were categorized and it consisted of food and organic, paper, rigid plastics, plastics film, baby diapers, glass, tetra pak, household hazardous waste, metal, rubber, textiles, garden waste and leather. The proportion of each wastes were approximately 64.67%, 9.36%, 9.22%, 5.33%, 3.51%, 2.53%, 1.37%, 1.05%, 0.84%, 0.85%, 0.80%, 0.27%, and 0.23%, respectively. Results from the analyses indicated that the food and organic waste are the major composition of household waste at Taman Universiti followed by the paper, rigid plastics, and plastic film. Meanwhile, the proportion of baby diapers, glass, tetra pak, household hazardous waste, metal, rubber, textiles, and garden decreasing accordingly. In addition, leather was recognized as the least category that contributed to the household waste.

  11. Determining the Magma Genesis of Mo Porphyry Deposits

    NASA Astrophysics Data System (ADS)

    Gaynor, S.; Coleman, D. S.; Rosera, J.

    2015-12-01

    The high flux of magma associated with super eruptions is hypothesized to rebuild the deep crust, altering the source(s) of subsequent magmatism. Climax-type Mo deposits are commonly generated immediately after eruption of large ignimbrites within a volcanic field, and provide an opportunity to understand the evolution of magma sources following high flux events. The Questa caldera of the Latir volcanic field, NM exposes a 10 Ma long record of pre-, syn- and post-ignimbrite intrusive and extrusive rocks, and hosts the Questa Climax-type Mo deposit. New detailed geochronology and geochemistry from Questa (including extensive sampling of subsurface rocks in the mine) permit detailed reconstruction of the temporal evolution of magma sources through the waxing and waning stages of super eruption magmatism. Comparison of chemical and isotopic data waxing, ignimbrite, Mo-mineralizing and waning stage magmas reveals several patterns. Waxing and waning magmas (waxing: 29-25.7 Ma; waning: 24.5-19 Ma) have intermediate trace elements and radiogenic isotopes relative to other magmatism (87Sr/86Sri=0.7050 to 0.7070, ɛNd=-5.2 to -7.2). Ignimbrite magmatism (25.5 Ma) is depleted in incompatible elements, enriched in MREE and HREE's and has more evolved radiogenic isotopes (87Sr/86Sri=0.7095, ɛNd=-8.0). Molybdenum mineralizing magmas (24.9-24.5 Ma), are enriched in incompatible elements, depleted in MREE and HREE's and have distinct radiogenic isotopes (87Sr/86Sri=0.7055 to 0.7075, ɛNd=-4.2 to -5.7). We suggest the lower crustal source of magmas changed during ignimbrite generation, and as a result, subsequent mineralizing magmas incorporated more juvenile, mafic components. This mantle influence is the metallogenesis for Climax-type deposits and indicates that deep crustal hybridization, rather than upper crustal differentiation, is pivotal in their generation. These results indicate that a lower crustal source of magmatism for a volcanic field is altered due to super eruptions.

  12. Landsat-D TM application to porphyry copper exploration

    NASA Technical Reports Server (NTRS)

    Abrams, M.; Brown, D.; Sadowski, R.; Lepley, L.

    1982-01-01

    For a number of years Landsat data have been used to locate areas of iron oxide occurrences which might be associated with hydrothermal alteration zones. However, the usefulness of the Landsat data was restricted because of certain limitations of the spectral information provided by Landsat. A new generation multispectral scanner will, therefore, be carried by the fourth Landsat, which is to be launched in July, 1982. This instrument, called the Thematic Mapper (TM), will have seven channels and provide data with 30 m spatial resolution. Two of the spectral channels (1.6 micron and 2.2 micron) should allow detection of hydrous minerals. Possible applications of Landsat-D TM data for copper exploration were studied on the basis of a comparison of Landsat data with simulated TM data acquired using an aircraft scanner instrument. Three porphyr copper deposits in Arizona were selected for the study. It is concluded that the new Landsat-D TM scanner will provide Exploration geologists with a new improved tool for surveying mineral resources on a global basis.

  13. Prevalence of cardiovascular disease risk factors among attendees of the Batu 9, Cheras Health Centre, Selangor, Malaysia.

    PubMed

    Amplavanar, N T; Gurpreet, K; Salmiah, M S; Odhayakumar, N

    2010-09-01

    This study describes the prevalence of selected cardiovascular disease (CVD) risk factors screened in patients 30 years and above attending a health centre in Cheras, Selangor. The study involved 3772 patients screened from March 2002 to June 2008. Risk factors screened included blood pressure, height, weight, serum total cholesterol, random blood sugar levels and smoking status. Majority of respondents were between 40 and 49 years of age (58.1%), males (64.7%) and ethnic Malays (74.4%). About two thirds (62.6%) were found to be overweight or obese, two fifths (40.2%) had hypercholesterolemia, a third (34.2%) had hypertension and 31.6% were smokers at some time. Overall 87% and 60% had at least one and two CVD risk factors respectively. Prevalence of four of the five risk factors screened was highest among the Malay middle aged men and lowest among the Chinese. Thus a substantial proportion of middle aged men were at high risk of CVD. Our findings show the need for ongoing monitoring of CVD risk factors and implementation of effective preventive strategies.

  14. The gamma dose assessment and pH correlation for various soil types at Batu Pahat and Kluang districts, Johor, Malaysia

    NASA Astrophysics Data System (ADS)

    Johar, Saffuwan Mohamed; Embong, Zaidi; Tajudin, Saiful Azhar Ahmad

    2016-01-01

    An assessment of absorbed dose and radiation hazard index as well as its relationship with soil pH was performed in this study. The area was chosen due to its variety of soil types from the Alluvial and the Sedentary group. The radioactivity concentration levels and the soil acidity were measured using the Canberra GC3518 high pure germanium with a relative efficiency of 35% at 1.3 MeV and the Takemura Soil pH and Moisture Tester (DM15), respectively. Overall results show the Holyrood-Lunas soil of Alluvial group recorded the highest external terrestrial gamma radiation dose rate (TGRD) of 286.4±37.9 nGy h-1 and radioactivity concentrations of 78.1±8.9 Bq kg-1 (226Ra), 410.5±55.4 Bq kg-1 (232Th) and 56.4±8.8 Bq kg-1 (40K), respectively, while the Peat soil of Alluvial group recorded the lowest TGRD of 4.4±2.7 nGy h-1 and radioactivity concentrations of 4.8±1.7 Bq kg-1 (226Ra), 3.1±1.1 Bq kg-1 (232Th) and 6.1±2.0 Bq kg-1 (40K), respectively. The estimated mean outdoor annual effective dose, the mean radium equivalent activity (Req) and the mean external (Hext) and internal hazard index (Hint) associated with the alluvial and sedentary soil group were evaluated at 0.15 and 0.20 mSv, 280 and 364 Bq kg-1, Hext = 0.78 and 1.01, and Hint = 0.93 and 1.26, respectively. Correlation analysis between 238U, 232Th and 40K with soil pH level for alluvial group was r = +0.68, +0.48 and 0, respectively, while for sedentary soil, the Pearson's, r = -0.30, -0.90 and +0.14, respectively.

  15. The gamma dose assessment and pH correlation for various soil types at Batu Pahat and Kluang districts, Johor, Malaysia

    SciTech Connect

    Johar, Saffuwan Mohamed; Embong, Zaidi; Tajudin, Saiful Azhar Ahmad

    2016-01-22

    An assessment of absorbed dose and radiation hazard index as well as its relationship with soil pH was performed in this study. The area was chosen due to its variety of soil types from the Alluvial and the Sedentary group. The radioactivity concentration levels and the soil acidity were measured using the Canberra GC3518 high pure germanium with a relative efficiency of 35% at 1.3 MeV and the Takemura Soil pH and Moisture Tester (DM15), respectively. Overall results show the Holyrood-Lunas soil of Alluvial group recorded the highest external terrestrial gamma radiation dose rate (TGRD) of 286.4±37.9 nGy h{sup −1} and radioactivity concentrations of 78.1±8.9 Bq kg{sup −1} ({sup 226}Ra), 410.5±55.4 Bq kg{sup −1} ({sup 232}Th) and 56.4±8.8 Bq kg{sup −1} ({sup 40}K), respectively, while the Peat soil of Alluvial group recorded the lowest TGRD of 4.4±2.7 nGy h{sup −1} and radioactivity concentrations of 4.8±1.7 Bq kg{sup −1} ({sup 226}Ra), 3.1±1.1 Bq kg{sup −1} ({sup 232}Th) and 6.1±2.0 Bq kg{sup −1} ({sup 40}K), respectively. The estimated mean outdoor annual effective dose, the mean radium equivalent activity (R{sub eq}) and the mean external (H{sub ext}) and internal hazard index (H{sub int}) associated with the alluvial and sedentary soil group were evaluated at 0.15 and 0.20 mSv, 280 and 364 Bq kg{sup −1}, H{sub ext} = 0.78 and 1.01, and H{sub int} = 0.93 and 1.26, respectively. Correlation analysis between 238U, {sup 232}Th and {sup 40}K with soil pH level for alluvial group was r = +0.68, +0.48 and 0, respectively, while for sedentary soil, the Pearson’s, r = −0.30, −0.90 and +0.14, respectively.

  16. Application of thematic mapper-type data over a porphyry-molybdenum deposit in Colorado

    NASA Technical Reports Server (NTRS)

    Rickman, D. L.; Sadowski, R. M.

    1983-01-01

    The objective of the study was to evaluate the utility of thematic mapper data as a source of geologically useful information for mountainous areas of varying vegetation density. Much of the processing was done in an a priori manner without prior ground-based information. This approach resulted in a successfull mapping of the alteration associated with the Mt. Emmons molybdenum ore body as well as several other hydrothermal systems. Supervised classification produced a vegetation map at least as accurate as the mapping done for the environmental impact statement. Principal components were used to map zones of general, subtle alteration and to separate hematitically stained rock from staining associated with hydrothermal activity. Decorrelation color composites were found to be useful field mapping aids, easily delineating many lithologies and vegetation classes of interest. The factors restricting the interpretability and computer manipulation of the data are examined.

  17. Speciation and leachability of copper in mine tailings from porphyry copper mining: influence of particle size.

    PubMed

    Hansen, Henrik K; Yianatos, Juan B; Ottosen, Lisbeth M

    2005-09-01

    Mine tailing from the El Teniente-Codelco copper mine situated in VI Region of Chile was analysed in order to evaluate the mobility and speciation of copper in the solid material. Mine tailing was sampled after the rougher flotation circuits, and the copper content was measured to 1150 mg kg (-1) dry matter. This tailing was segmented into fractions of different size intervals: 0-38, 38-45, 45-53, 53-75, 75-106, 106-150, 150-212, and >212 microm, respectively. Copper content determination, sequential chemical extraction, and desorption experiments were carried out for each size interval in order to evaluate the speciation of copper. It was found that the particles of smallest size contained 50-60% weak acid leachable copper, whereas only 32% of the copper found in largest particles could be leached in weak acid. Copper oxides and carbonates were the dominating species in the smaller particles, and the larger particles contained considerable amounts of sulphides.

  18. Prediction of AMD generation potential in mining waste piles, in the Sarcheshmeh porphyry copper deposit, Iran.

    PubMed

    Modabberi, Soroush; Alizadegan, Ali; Mirnejad, Hassan; Esmaeilzadeh, Esmat

    2013-11-01

    This study investigates the possibility of acid mine drainage (AMD) generation in active and derelict mine waste piles in Sarcheshmeh Copper Mine produced in several decades, using static tests including acid-base accounting (ABA) and net acid-generating pH (NAGpH). In this study, 51 composite samples were taken from 11 waste heaps, and static ABA and NAGpH tests were carried out on samples. While some piles are acid producing at present and AMD is discharging from the piles, most of them do not show any indication on their AMD potential, and they were investigated to define their acid-producing potential. The analysis of data indicates that eight waste piles are potentially acid generating with net neutralization potentials (NNPs) of -56.18 to -199.3, net acid generating of 2.19-3.31, and NPRs from 0.18 to 0.44. Other waste piles exhibited either a very low sulfur, high carbonate content or excess carbonate over sulfur; hence, they are not capable of acid production or they can be considered as weak acid producers. Consistency between results of ABA and NAGpH tests using a variety of classification criteria validates these tests as powerful means for preliminary evaluation of AMD/ARD possibilities in any mining district. It is also concluded that some of the piles with very negative NNPs are capable to produce AMD naturally, and they can be used in heap leaching process for economic recovery of trace amounts of metals without applying any biostimulation methods.

  19. Recognition of the geologic framework of porphyry deposits on ERTS-1 imagery

    NASA Technical Reports Server (NTRS)

    Wilson, J. C. (Principal Investigator); Camp, L. W.

    1973-01-01

    The author has identified the following significant results. Preliminary analysis of a mosaic composing 20 individual ERTS-1 frames that covers most of Nevada and western Utah reveals both new and old structural features. Three separate provinces, the Basin and Range, the southern extension of the Columbia River Plateau volcanics, and the western edge of the Colorado Plateau are easily distinguishable. A west-northwest cross or transverse structural trend, the Las Vegas Shear zone, is present in the region running from the Sierra Nevada to Lake Mead. The Sevier, Hurricane and Grand Wash faults that define the Wasateh-Jerome structural zone, can be traced further on the ERTS-1 imagery than on existing tectonic maps. By use of a stereo viewer on the side-lap coverage of ERTS-1 imagery, it is possible in some instances to determine the direction of sedimentary beds, enabling anticlines and synclines to be mapped. Other geologic features, faults, direction of throw on faults, recent basalt flow contacts with older rhyolitic tuffs, volcanic cones, and subsidences can also be mapped.

  20. Arc-related porphyry molybdenum deposit model: Chapter D in Mineral deposit models for resource assessment

    USGS Publications Warehouse

    Taylor, Ryan D.; Hammarstrom, Jane M.; Piatak, Nadine M.; Seal, Robert R., II

    2012-01-01

    Geoenvironmental concerns are generally low because of low volumes of sulfide minerals. Most deposits are marginally acid-generating to non-acid-generating with drainage waters being near-neutral pH because of the acid generating potential of pyrite being partially buffered by late-stage calcite-bearing veins. The low ore content results in a waste:ore ratio of nearly 1:1 and large tailings piles from the open-pit method of mining.

  1. Terrain Analysis Procedural Guide for Soil. Report Number 6 in the ETL Series on Guides for Army Terrain Analysts

    DTIC Science & Technology

    1981-02-01

    CL Extrusive Basaltic & humid A ML, CL Volcanic tropical or B CH, MH subtrupical C ML-MI-, MX, CH arid A ML-CL, ML, GM 1 B, CH, CL, WX, ML-CL, GC Slate...rhyolite porphyry, trachyte porphyry, dacite porphyry, basalt porphyry, augitite porphyry, granite, syenite porphyry, syenite, diorite porphyry, diorite...of bedrock listed below (when bedrock appears near the surface). (1) Sandstone. (2) Shale. (3) Limestone. (4) Granite. (5) Basalt . (6) Volcanic. (7

  2. Counting with Colours? Effect of Colours on the Numerical Abilities of House Crows (Corvus splendens) and Common Myna (Acridotheres tristis).

    PubMed

    Rahman, Nor Amira Abdul; Ali, Zalila; Zuharah, Wan Fatma; Fadzly, Nik

    2016-08-01

    Kami menjalankan beberapa eksperimen aviari untuk mengenal pasti kesan warna ke atas pemilihan kuantiti oleh dua jenis burung, burung gagak (Corvus splendens) dan burung tiung (Acridotheres tristis). Cacing dalam kuantiti berbeza (tujuh pembahagian berlainan) diberikan kepada burung dalam turutan rawak menggunakan cacing dicat dengan warna merah bagi eksperimen 1 dan menggunakan cacing dicat warna hijau bagi eksperimen 2. Kedua-dua warna cacing merah dan hijau tidak memberi kesan kepada pemilihan kuantiti gagak (merah: ANOVA: F6,30 = 1.748, p = 0.144; dan hijau: ANOVA: F6,30 = 1.085, p = 0.394). Namun demikian, burung tiung menunjukkan kesan pengaruh kuat bagi warna merah ke atas pemilihan kuantiti (ANOVA: F6,30 = 2.922, p = 0.023), dengan burung berjaya memilih jumlah makanan yang lebih besar antara dua cawan, tetapi tidak apabila cacing berwarna hijau ditawarkan (ANOVA: F6,30 = 1.183, p = 0.342). Dalam eksperimen seterusnya, hipotesis kami ialah kedua-dua burung gagak dan burung tiung akan memilih makanan berwarna merah berbanding warna hijau apabila faktor jumlah makanan adalah sama. Kami memilih untuk menguji warna merah dan warna hijau kerana kedua-dua warna memainkan peranan penting dalam pemilihan makanan burung. Keputusan menunjukkan tiada perbezaan signifikan bagi pemilihan cacing merah dan hijau bagi kedua-dua burung gagak (ANOVA: F6,30 = 2.310, p = 0.06) dan burung tiung (ANOVA: F6,30 = 0.823, p = 0.561).

  3. Progressive mixing of isotopic reservoirs during magma genesis at the Sierrita porphyry copper deposit, Arizona: Inverse solutions

    SciTech Connect

    Anthony, E.Y.; Titley, S.R. )

    1988-09-01

    Trace-element and Sr and Nd isotopic compositions have been determined for a suite of calc-alkaline rocks from southeastern Arizona. The suite consists of andesitic and rhyolitic rocks (67 m.y. old) intruded by granodiorite and granite (62-58 m.y. old). It is situated within Proterozoic basement of 1.7 to 1.65 Ga age. Isotopic composition and chemical evolution are well correlated throughout the suite. The andesite has the least negative {epsilon}{sub Nd} ({epsilon}{sub Nd}(t{sub igneous}) = {minus}4.3) and smallest {sup 87}Sr/{sup 86}Sr{sub o} (0.7069). It is also the oldest and chemically most primitive, having the lowest concentrations of Rb, SiO{sub 2}, and highest concentrations of the transition elements. These parameters change through the system to the youngest unit (granite) which has the most negative {epsilon}{sub Nd}(8-5), the greatest {sup 87}Sr/{sup 86}Sr{sub o} (0.7092), and is most chemically evolved. The authors interpret these trends as resulting from a continuous process of progressive assimilation in which mafic magmas invade and incorporate continental crust. The assimilated continental crust was probably intermediate to mafic in composition and of amphibolite grade. Phase relations among minerals indicate that it was hydrous and oxidizing. Inverse methods have been applied to equations for assimilation and fractional crystallization whose use assumes periodic tapping of a single magma body. Such modeling yields insight into the size and chemistry of the magma system.

  4. Paleozoic magmatism and porphyry Cu-mineralization in an evolving tectonic setting in the North Qilian Orogenic Belt, NW China

    USGS Publications Warehouse

    Qiu, Kun-Feng; Deng, Jun; Taylor, Ryan D.; Song, Kai-Rui; Song, Yao-Hui; Li, Quan-Zhong; Goldfarb, Richard J.

    2016-01-01

    The NWW-striking North Qilian Orogenic Belt records the Paleozoic accretion–collision processes in NW China, and hosts Paleozoic Cu–Pb–Zn mineralization that was temporally and spatially related to the closure of the Paleo Qilian-Qinling Ocean. The Wangdian Cu deposit is located in the eastern part of the North Qilian Orogenic Belt, NW China. Copper mineralization is spatially associated with an altered early Paleozoic porphyritic granodiorite, which intruded tonalites and volcaniclastic rocks. Alteration zones surrounding the mineralization progress outward from a potassic to a feldspar-destructive phyllic assemblage. Mineralization consists mainly of quartz-sulfide stockworks and disseminated sulfides, with ore minerals chalcopyrite, pyrite, molybdenite, and minor galena and sphalerite. Gangue minerals include quartz, orthoclase, biotite, sericite, and K-feldspar. Zircon LA-ICPMS U–Pb dating of the ore-bearing porphyritic granodiorite yielded a mean 206Pb/238U age of 444.6 ± 7.8 Ma, with a group of inherited zircons yielding a mean U–Pb age of 485 ± 12 Ma, consistent with the emplacement age (485.3 ± 6.2 Ma) of the barren precursor tonalite. Rhenium and osmium analyses of molybdenite grains returned model ages of 442.9 ± 6.8 Ma and 443.3 ± 6.2 Ma, indicating mineralization was coeval with the emplacement of the host porphyritic granodiorite. Rhenium concentrations in molybdenite (208.9–213.2 ppm) suggest a mantle Re source. The tonalities are medium-K calc-alkaline. They are characterized by enrichment of light rare-earth elements (LREEs) and large-ion lithophile elements (LILEs), depletion of heavy rare-earth elements (HREEs) and high-field-strength elements (HFSEs), and minor negative Eu anomalies. They have εHf(t) values in the range of +3.6 to +11.1, with two-stage Hf model ages of 0.67–1.13 Ga, suggesting that the ca. 485 Ma barren tonalites were products of arc magmatism incorporating melts from the mantle wedge and the lithosphere. In contrast, the 40-m.y.-younger ore-bearing porphyritic granodiorite is sub-alkaline and peraluminous. They are enriched in LREEs and LILEs, depleted in HFSEs, and show weak negative Eu anomalies. They displayεHf(t) values of captured or inherited zircons in the range of +8.5 to +10.0, and younger two-stage Hf model ages of 0.78 Ga and 0.86 Ga, similar to those of ca. 485 Ma tonalite. The ca. 445 Ma zircons have εHf(t) values of −2.1 to +9.9, with two-stage Hf model ages of 0.75–1.27 Ga. Moreover, they have relatively high oxygen fugacity than that of the precursor barren tonalite. The ca. 445 Ma magmas at Wangdian thus formed in a subduction setting, and incorporated melts from the subduction-modified lithosphere that had previously been enriched by additions of chalcophile and siderophile element-rich materials by the earlier magmatism and metasomatism during the Paleo Qilian-Qinling Ocean subduction event.

  5. Paleozoic magmatism and porphyry Cu-mineralization in an evolving tectonic setting in the North Qilian Orogenic Belt, NW China

    NASA Astrophysics Data System (ADS)

    Qiu, Kun-Feng; Deng, Jun; Taylor, Ryan D.; Song, Kai-Rui; Song, Yao-Hui; Li, Quan-Zhong; Goldfarb, Richard J.

    2016-05-01

    The NWW-striking North Qilian Orogenic Belt records the Paleozoic accretion-collision processes in NW China, and hosts Paleozoic Cu-Pb-Zn mineralization that was temporally and spatially related to the closure of the Paleo Qilian-Qinling Ocean. The Wangdian Cu deposit is located in the eastern part of the North Qilian Orogenic Belt, NW China. Copper mineralization is spatially associated with an altered early Paleozoic porphyritic granodiorite, which intruded tonalites and volcaniclastic rocks. Alteration zones surrounding the mineralization progress outward from a potassic to a feldspar-destructive phyllic assemblage. Mineralization consists mainly of quartz-sulfide stockworks and disseminated sulfides, with ore minerals chalcopyrite, pyrite, molybdenite, and minor galena and sphalerite. Gangue minerals include quartz, orthoclase, biotite, sericite, and K-feldspar. Zircon LA-ICPMS U-Pb dating of the ore-bearing porphyritic granodiorite yielded a mean 206Pb/238U age of 444.6 ± 7.8 Ma, with a group of inherited zircons yielding a mean U-Pb age of 485 ± 12 Ma, consistent with the emplacement age (485.3 ± 6.2 Ma) of the barren precursor tonalite. Rhenium and osmium analyses of molybdenite grains returned model ages of 442.9 ± 6.8 Ma and 443.3 ± 6.2 Ma, indicating mineralization was coeval with the emplacement of the host porphyritic granodiorite. Rhenium concentrations in molybdenite (208.9-213.2 ppm) suggest a mantle Re source. The tonalities are medium-K calc-alkaline. They are characterized by enrichment of light rare-earth elements (LREEs) and large-ion lithophile elements (LILEs), depletion of heavy rare-earth elements (HREEs) and high-field-strength elements (HFSEs), and minor negative Eu anomalies. They have εHf(t) values in the range of +3.6 to +11.1, with two-stage Hf model ages of 0.67-1.13 Ga, suggesting that the ca. 485 Ma barren tonalites were products of arc magmatism incorporating melts from the mantle wedge and the lithosphere. In contrast, the 40-m.y.-younger ore-bearing porphyritic granodiorite is sub-alkaline and peraluminous. They are enriched in LREEs and LILEs, depleted in HFSEs, and show weak negative Eu anomalies. They display εHf(t) values of captured or inherited zircons in the range of +8.5 to +10.0, and younger two-stage Hf model ages of 0.78 Ga and 0.86 Ga, similar to those of ca. 485 Ma tonalite. The ca. 445 Ma zircons have εHf(t) values of -2.1 to +9.9, with two-stage Hf model ages of 0.75-1.27 Ga. Moreover, they have relatively high oxygen fugacity than that of the precursor barren tonalite. The ca. 445 Ma magmas at Wangdian thus formed in a subduction setting, and incorporated melts from the subduction-modified lithosphere that had previously been enriched by additions of chalcophile and siderophile element-rich materials by the earlier magmatism and metasomatism during the Paleo Qilian-Qinling Ocean subduction event.

  6. Trace elements in pyrite from the Petropavlovsk gold-porphyry deposit (Polar Urals): Results of LA-ICP-MS analysis

    NASA Astrophysics Data System (ADS)

    Vikentiev, I. V.; Abramova, V. D.; Ivanova, Yu. N.; Tyukova, E. E.; Kovalchuk, E. V.; Bortnikov, N. S.

    2016-09-01

    The first study of the pyrite composition from gold deposit in the Urals by the LA-ICP-MS method has been carried out. In the pyrite high contents of Au (up to 49 ppm), Ag (105 ppm), and other micronutrients (As (417 ppm), Ag (105 ppm), Co (2825 ppm), Ni (75 ppm), Cu (1442 ppm), and Zn (19 ppm)) were detected. Furthermore, an increase in the concentrations of trace elements from early to later generations of pyrite (from Py-1 to Py-3) Au, Ag, Te, Sn, Te, and Bi and depletion of Co, As, and Ni have been revealed. Gold is mainly concentrated in the pyrite of the second generation (Py-2) and occurs mostly as an "invisible" form with prevalence of nano-sized particles of native Au, similar in composition to electrum AuAg, as well as Au- and Au-Ag tellurides. The presence in the pyrite of admixtures of Cu, Co, Ni, Pb, As, and Te, possibly favors the entrance of Au into it (up to 5-50 ppm), while in common pyrite, poor in the mentioned impurities, the gold content is <1 ppm.

  7. Research on recognition of the geologic framework of porphyry copper deposits on ERTS-1 imagery. [New Guinea, Alaska, and Colorado

    NASA Technical Reports Server (NTRS)

    Wilson, J. C. (Principal Investigator)

    1975-01-01

    The author has identified the following significant results. Many new linear and circular features were found. These features prompted novel tectonic classification and analysis especially in the Ray and Ely areas. Tectonic analyses of the Ok Tedi, Tanacross, and Silvertone areas follow conventional interpretations. Circular features are mapped in many cases and are interpreted as exposed or covered intrusive centers. The small circular features reported in the Ok Tedi test area are valid and useful correlations with tertiary intrusion and volcanism in this remote part of New Guinea. Several major faults of regional dimensions, such as the Denali fault in Alaska and the Colorado mineral belt structures in Colorado are detected in the imagery. Many more faults and regional structures are found in the imagery than exist on present maps.

  8. halogen Contents of igneous minerals as indicators of magmatic evolution of rocks associated with the Ray porphyry copper deposit, Arizona

    USGS Publications Warehouse

    Banks, Norman G.

    1976-01-01

    The contents of Cl, F, and H2O+ (calculated) in some hydrous igneous minerals in intrusive rocks of Laramide age (70-60 m.y.) near Ray, Ariz., appear to be related to the age and the chemistry of the whole-rock samples. Apatite and biotite in younger, more silicic rocks contain more F but less Cl and H2O+ than apatite and biotite in older, more mafic rock; the same relations hold for F and H2O+ in sphene. Correlations of the abundance of Cl, F, and H2O+ in hornblende with rock chemistry and age are not as strong as for apatite, biotite, and sphene; igneous (?) epidote does not contain Cl and F in amounts detectable by electron microprobe analysis. The contents of Cl, F, and H2O+ in whole-rock samples decrease with increasing differentiation index and decreasing age. Data for a single pluton of variable composition mirror the results for a suite of different plutons and dikes. The data are satisfactorily although not exclusively explained by postulating that the melts each contained progressively less Cl, F, and H2O and that the hydrons minerals consumed most of the Cl, F, and H2O in the magmas. The data may also be explained by postulating that (1) the stocks evolved Cl-bearing water during their ascent and crystallization, or that (2) Cl and H2O were concentrated during differentiation of the stocks but the minerals failed to record their buildup. Both alternative explanations find problems with and require special conditions to satisfy field, chemical, and experimental data. If many of the special conditions are not met, a nearby batholithic parent to the stocks is not a favorable source of the mineralized fluids at Ray. Propylitic alteration of biotite results in Cl-poor chlorites and may have provided some Cl to hydrothermal fluids; biotite may have also supplied some F to propylitizing fluids through alteration.

  9. Isolation and characterization of lost copper and molybdenum particles in the flotation tailings of Kennecott copper porphyry ores

    NASA Astrophysics Data System (ADS)

    Tserendavga, Tsend-Ayush

    The importance of flotation separation has long been, and continues to be, an important technology for the mining industry, especially to metallurgical engineers. However, the flotation process is quite complex and expensive, in addition to being influenced by many variables. Understanding the variables affecting flotation efficiency and how valuable minerals are lost to the tailings gives metallurgists an advantage in their attempts to increase efficiency by designing operations to target the areas of greatest potential value. A successful, accurate evaluation of lost minerals in the tailings and appropriate solutions to improve flotation efficiency can save millions of dollars in the effective utilization of our mineral resources. In this dissertation research, an attempt has been made to understand the reasons for the loss of valuable mineral particles in the tailings from Kennecott Utah Copper ores. Possibilities include liberation, particle aggregation (slime coating) and surface chemistry issues associated with the flotation separation. This research generally consisted of three main aspects. The first part involved laboratory flotation experiments and factors, which affect the flotation efficiency. Results of flotation testing are reported that several factors such as mineral exposure/liberation and slime coating and surface oxidation strongly affect the flotation efficiency. The second part of this dissertation research was to develop a rapid scan dual energy (DE) methodology using 2D radiography to identify, isolate, and prepare lost sulfide mineral particles with the advantages of simple sample preparation, short analysis time, statistically reliable accuracy and confident identification. The third part of this dissertation research was concerned with detailed characterization of lost particles including such factors as liberation, slime coating, and surface chemistry characteristics using advanced analytical techniques and instruments. Based on the results from characterization, the extent to which these factors contribute to the loss of sulfide mineral particles in the tailings were determined.

  10. Development of Learning Devices through Problem Based Learning Model Based on the Context of Aceh Cultural to Improve Mathematical Communication Skills and Social Skills of SMPN 1 Muara Batu Students

    ERIC Educational Resources Information Center

    Aufa, Mahrani; Saragih, Sahat; Minarni, Ani

    2016-01-01

    The purposes of this study were:1) Developed problem-based on learning tools in the cultural context of Aceh (PBM-BKBA) who meet the criteria are valid, practical and effective; 2) Described the improvement of communication capabilities mathematics and social skills of students using the PBM-BKBA developed; and 3) Described the process of student…

  11. Permafrost, Seasonally Frozen Ground, Snow Cover and Vegetation in the USSR

    DTIC Science & Technology

    1984-12-01

    intrusive ( syenite -porphyries, porphyries); 5 - alluvial complexes (sandy silty loams*, sands, clayey silty loams’*") QlI-lII...fissured, fissured-stratum; 4 - syenite -porphyry, porphyry (e, T3-K); 5 - alluvial gravel, sands, sandy-silty loams, peat formation (a w-IY

  12. On the new analytical solution for a well in Cartesian coordinates with MODFLOW comparisons.

    PubMed

    Batu, Vedat

    2014-01-01

    In this paper, the comparison process of Batu (2012) generalized three-dimensional well hydraulics solution for confined aquifers in Cartesian coordinates with MODFLOW is presented. First, a brief description of Batu (2012) solution along with the governing equations and some of its key features are described. The final average drawdown expression in an observation well is given with the conversion expressions from Cartesian to radial coordinates. A generalized comparison using Batu (2012), Hantush (1964), and MODFLOW (Harbaugh et al. 2000), for vertical wells in horizontally isotropic aquifers, that is, ayx  = Ky /Kx  = 1, is presented. Comparisons are also presented with Batu (2012) and MODFLOW for horizontally anisotropic aquifers, that is, ayx  ≠ 1. After that comparisons are presented for horizontal wells between Batu (2012) and MODFLOW.

  13. The effect of pressure on sulphur speciation in mid- to deep-crustal arc magmas and implications for the formation of porphyry copper deposits

    NASA Astrophysics Data System (ADS)

    Matjuschkin, Vladimir; Blundy, Jon D.; Brooker, Richard A.

    2016-07-01

    Piston cylinder experiments are used to investigate the effect of oxygen fugacity (ƒO2) on sulphur speciation and phase relations in arc magmas at 0.5-1.5 GPa and 840-950 °C. The experimental starting composition is a synthetic trachyandesite containing 6.0 wt% H2O, 2880 ppm S, 1500 ppm Cl and 3800 ppm C. Redox conditions ranging from 1.7 log units below the Ni-NiO buffer (NNO - 1.7) to NNO + 4.7 were imposed by solid-state buffers: Co-CoO, Ni-NiO, Re-ReO2 and haematite-magnetite. All experiments are saturated with a COH fluid. Experiments produced crystal-bearing trachydacitic melts (SiO2 from 60 to 69 wt%) for which major and volatile element concentrations were measured. Experimental results demonstrate a powerful effect of oxidation state on phase relations. For example, plagioclase was stable above NNO, but absent at more reduced conditions. Suppression of plagioclase stability produces higher Al2O3 and CaO melts. The solid sulphur-bearing phases and sulphur speciation in the melt are strong functions of ƒO2, as expected, but also of pressure. At 0.5 GPa, the anhydrite stability field is intersected at NNO ≥ +2, but at 1.0 and 1.5 GPa, experiments at the same ƒO2 produce sulphides and the stability field of sulphate moves towards higher ƒO2 by ~1 log unit at 1.0 GPa and ~1.5 log units at 1.5 GPa. As a result, models that appeal to high oxidation state as an important control on the mobility of Cu (and other chalcophiles) during crustal differentiation must also consider the enhanced stability of sulphide in deep- to mid-crustal cumulates even for relatively oxidized (NNO + 2) magmas. Experimental glasses reproduce the commonly observed minimum in sulphur solubility between the S2- and S6+ stability fields. The solubility minimum is not related to the Fe content (Fe2+/Fe3+ or total) of the melt. Instead, we propose this minimum results from an unidentified, but relatively insoluble, S-species of intermediate oxidation state.

  14. A deposit scale mineral prospectivity analysis: A comparison of various knowledge-driven approaches for porphyry copper targeting in Seridune, Iran

    NASA Astrophysics Data System (ADS)

    Abedi, Maysam; Mostafavi Kashani, Seyed Bagher; Norouzi, Gholam-Hossain; Yousefi, Mahyar

    2017-04-01

    In this paper, an application of a knowledge-driven mineral prospectivity mapping (MPM) approach so-called ;the evidential belief functions (EBFs) using Dempster-Shafer's rule of combination; is proposed. This technique is used to weight and integrate a large scale exploration dataset in order to localize prospects for definition of further exploration drilling sites. In this study, exploration datasets of Seridune copper deposit in the Kerman province, SE Iran used for the methodology. In this regard, geophysical evidence layers extracted from interpretation of magnetic and electrical surveys, geological evidence layers derived via the geological datasets (i.e. lithology, fault and alteration), and geochemical evidence maps were generated and integrated for MPM. Furthermore, various MPM approaches including outranking, index overlay and fuzzy logic methods were examined for comparison with the introduced method. To evaluate and compare the efficiency of the methods, the productivity of the drilled boreholes (Cu concentration multiplied by its ore thickness along each drilled borehole) was used to validate the generated prospectivity models. The results showed higher efficiency of the Dempster-Shafer's model in comparison with the prospectivity models generated using other MPM approaches.

  15. The transport of gold and molybdenum through hydration in aqueous vapor and vapor-like fluids: Application to porphyry Au and Mo deposits

    NASA Astrophysics Data System (ADS)

    Hurtig, N. C.; Williams-Jones, A. E.

    2013-12-01

    The hypothesis that vapor is a viable medium for the transport of gold and molybdenum in ore forming magmatic-hydrothermal systems is supported by fluid inclusion data, analyses of volcanic gas condensates and the occurrence of metal-rich incrustations around fumaroles. Experiments have shown that hydration of metal species in water vapor is an essential factor in making such transport possible [1,2,3]. Indeed, hydration has been shown to increase concentrations of Au and Mo in the aqueous vapor phase by several orders of magnitude over those calculated using volatility data. Nevertheless metal concentrations determined experimentally in previous studies are substantially lower than those reported for vapor inclusions in magmatic hydrothermal systems, and are limited to one or two dominant hydrated metal species. To bridge this gap, we performed a series of new experiments extending the density-range to near critical vapor density, and intermediate-density in the case of supercritical fluids. Experiments were carried out in batch-type Ti autoclaves at temperatures between 300 and 500 °C and pressures up to 366 bar in HCl-bearing water vapor. Oxygen fugacity was buffered either by the assemblage MoO2/MoO3 or WO2/WO3 or graphite. Gold and molybdenum concentrations measured in the experimental condensates ranged from 0.9 ppb and 3 ppm in low-density vapor at 300 °C to 4.6 ppm and 481 ppm at 297 bar and 400 °C, respectively. The fugacity of both metals increased exponentially with increasing water fugacity, resulting in an increase in metal solubility between 1 and 3 orders of magnitude from the lowest pressures investigated. Curves representing the experimentally determined relationship between metal fugacity and fH2O were fitted to a step-wise hydration model to extract a set of logarithmic equilibrium constants for P and T extrapolation. We have used the above data to model Au and Mo mobilization in magmatic-hydrothermal vapor plumes. This modeling shows that the solubility of AuCl(H2O)y is dependent on oxygen and HCl fugacity, density and the P-T evolution of the fluid, and that there is a solubility maximum between 400 and 600 °C. The behavior of AuCl(H2O)y suggests, that efficient gold transport is favored by the exsolution of an intermediate-density fluid from the magma, which expands upwards into a vapor-like fluid and precipitates the gold when conditions fall below the critical point of water at the top of the plume. Equilibrium calculations for MoO3(H2O)y show that Mo transport reaches a maximum in SO2-dominated gas. We therefore conclude that molybdenite likely does not precipitate from the vapor directly but rather from the condensed liquid. [1] Migdisov et al. (1999) GCA 63, 3817-3827. [2] Archibald et al. (2001) GCA 65, 4413-4423. [3] Rempel et al. (2006) GCA 70, 687-696.

  16. Economic filters for evaluating porphyry copper deposit resource assessments using grade-tonnage deposit models, with examples from the U.S. Geological Survey global mineral resource assessment: Chapter H in Global mineral resource assessment

    USGS Publications Warehouse

    Robinson,, Gilpin R.; Menzie, W. David

    2012-01-01

    One implication of the economic filter results for undiscovered copper resources is that global copper supply will continue to be dominated by production from a small number of giant deposits. This domination of resource supply by a small number of producers may increase in the future, because an increasing proportion of new deposit discoveries are likely to occur in remote areas and be concealed deep beneath covering rock and sediments. Extensive mineral exploration activity will be required to meet future resource demand, because these deposits will be harder to find and more costly to mine than near-surface deposits located in more accessible areas. Relatively few of the new deposit discoveries in these high-cost settings will have sufficient tonnage and grade characteristics to assure positive economic returns on development and exploration costs.

  17. Questa Baseline and Pre-Mining Ground-Water Quality Investigation. 13. Mineral Microscopy and Chemistry of Mined and Unmined Porphyry Molybdenum Mineralization Along the Red River, New Mexico: Implications for Ground- and Surface-Water Quality

    USGS Publications Warehouse

    Plumlee, Geoff; Lowers, Heather; Ludington, Steve; Koenig, Alan; Briggs, Paul

    2005-01-01

    This report is one in a series presenting results of an interdisciplinary U.S. Geological Survey (USGS) study of ground-water quality in the lower Red River watershed prior to open-pit and underground molybdenite mining at Molycorp's Questa mine. The stretch of the Red River watershed that extends from just upstream of the town of Red River to just above the town of Questa includes several mineralized areas in addition to the one mined by Molycorp. Natural erosion and weathering of pyrite-rich rocks in the mineralized areas has created a series of erosional scars along this stretch of the Red River that contribute acidic waters, as well as mineralized alluvial material and sediments, to the river. The overall goal of the USGS study is to infer the pre-mining ground-water quality at the Molycorp mine site. An integrated geologic, hydrologic, and geochemical model for ground water in the mineralized but unmined Straight Creek drainage is being used as an analogue for the geologic, geochemical, and hydrologic conditions that influenced ground-water quality and quantity at the mine site prior to mining. This report summarizes results of reconnaissance mineralogical and chemical characterization studies of rock samples collected from the various scars and the Molycorp open pit, and of drill cuttings or drill core from bedrock beneath the scars and adjacent debris fans.

  18. Preshot Geophysical Properties of Palanquin Crater Site

    DTIC Science & Technology

    2007-11-02

    The rocks at the Palanquin site are of volcanic origin, and consist predominantly of trachyte porphyry of the Ribbon Cliff formation of Pliocene age...Pyroclastic volcanic tuff underlies the trachyte porphyry at a depth of 175 m and caps low hills adjacent to the site. The volcanic units have a

  19. Physics Laboratory Investigation of Vocational High School Field Stone and Concrete Construction Techniques in the Central Java Province (Indonesia)

    ERIC Educational Resources Information Center

    Purwandari, Ristiana Dyah

    2015-01-01

    The investigation aims in this study were to uncover the observations of infrastructures and physics laboratory in vocational high school for Stone and Concrete Construction Techniques Expertise Field or Teknik Konstruksi Batu dan Beton (TKBB)'s in Purwokerto Central Java Province, mapping the Vocational High School or Sekolah Menengah Kejuruan…

  20. The Reinforcement to the Citizen Participation in Taking Care of the Environmental Protection Towards a Green Moral Concept-Based Sustainable Development

    ERIC Educational Resources Information Center

    Syahri, Mohamad

    2016-01-01

    The research sites were "Blitar, Malang" and "Batu" in East Java Province, Indonesia since those areas are regarded to have problems of environmental crises. In the data collection, this study made use of four methods, namely: a) observation, b) In-depth Interviews, c) documentation, and d) focus group discussion. The results…

  1. Occurrence of Giardia and Cryptosporidium (oo)cysts in the river water of two recreational areas in Selangor, Malaysia.

    PubMed

    Azman, J; Init, I; Wan Yusoff, W S

    2009-12-01

    This study is the first report on the occurrence of Giardia and Cryptosporidium (oo)cysts in recreational rivers water from Malaysia. It was carried out in water samples at two rivers, 'Sungai Congkak' and 'Sungai Batu', located in Selangor State. The occurrence of both Giardia lamblia and Cryptosporidium parvum (oo)cysts was higher in Sungai Congkak (50% or 15/30 and 10% or 3/30 respectively) than Sungai Batu (16% or 5/30 and 3.3% or 1/30 respectively). The mean density of cysts/L was 0.72 in Sungai Congkak and 0.023 in Sungai Batu, and that of oocysts/L was 0.023 in Sungai Congkak and 0.0033 in Sungai Batu, showing that the occurrence of Giardia was higher and more frequent than Cryptosporidium in both rivers. Sungai Congkak also showed higher faecal coliforms count (ranging from 0.48x10³ to 73x10³ CFU/100 mL) than Sungai Batu (0.41x10³ to 16x10³ CFU/100 mL). On the other hand, the Giardia and Cryptosporidium (oo)cysts and faecal coliforms were more concentrated at the downstream station, followed by midstream and upstream stations which might be due to human factors where settlements and recreation areas were located around and between midstream and downstream stations. The (oo)cysts and faecal coliforms also increased during public holidays due to the significantly higher number of visitors (bathers) compared with the week days. All the parameters (physical, faecal coliforms and rainfall) did not show consistent significant correlation (based on r values of Pearson correlation analysis) with both protozoa, therefore these parameters are not suitable as indicator for the presence of Giardia and Cryptosporidium (oo)cysts in both rivers.

  2. Potassium-Argon Age of Devils Tower, Wyoming.

    PubMed

    Bassett, W A

    1961-10-27

    Devils Tower consists of columnar phonolite porphyry which contains large phenocrysts of orthoclase. Potassiumargon determinations on the orthoclase indicate an age of 40.5 million years +/- 4 percent. This is consistent with the geologically accepted Tertiary age.

  3. Dissolved volatile concentrations in an ore-forming magma

    USGS Publications Warehouse

    Lowenstern, J. B.

    1994-01-01

    Infrared spectroscopic measurements of glass inclusions within quartz phenocrysts from the Plinian fallout of the 22 Ma tuff of Pine Grove show that the trapped silicate melt contained high concentrations of H2O and CO2. Intrusive porphyries from the Pine Grove system are nearly identical in age, composition, and mineralogy to the tephra, and some contain high-grade Mo mineralization. Assuming that the porphyry magmas originally contained similar abundances of volatile components as the erupted rocks, they would have been saturated with fluid at pressures far greater than those at which the porphyries were emplaced and mineralized. The data are consistent with formation of Climax-type Mo porphyry deposits by prolonged fluid flux from a large volume of relatively Mo-poor (1-5 ppm) magma. -from Author

  4. Geochronology and geochemistry of Eocene potassic felsic intrusions in the Nangqian basin, eastern Tibet: Tectonic and metallogenic implications

    NASA Astrophysics Data System (ADS)

    Xu, Yue; Bi, Xian-Wu; Hu, Rui-Zhong; Chen, You-wei; Liu, He-qing; Xu, Lei-luo

    2016-03-01

    The Jinshajiang-Ailaoshan copper belt is the most significant porphyry copper belt in eastern Tibet. In the northern segment of this belt within the Nangqian basin, which occurs 100 km east of the Yulong porphyry copper deposit, several felsic intrusions have been recently discovered. The Yulong porphyry copper deposit is one of the largest porphyry copper deposits in China, and it is associated with peraluminous adakitic rocks formed in a post-collisional setting. The Nangqian felsic intrusions vary from syenite porphyry to monzonite porphyry in rock types. No significant Cu-Au mineralization has been found in the Nangqian felsic intrusions despite extensive exploration in recent years. LA-ICP-MS zircon U-Pb dating reveals that the Nangqian syenite porphyry and monzonite porphyry were emplaced at 35.6±0.3 Ma and from 39.5±0.3 to 37.4±0.3 Ma, respectively, similar to the age of the Yulong porphyry copper deposit. The Nangqian felsic intrusions are characterized by metaluminous compositions (A/CNK = 0.82-1.01), and they share some common features with shoshonites such as high K2O contents (4.58-5.58 wt.%), high K2O/Na2O ratios (0.92-1.28), LREE-LILE enrichments and negative Nb-Ta-Ti-P anomalies, as well as with adakites derived from an eclogite-facies source with high Al2O3 (14.98-15.74 wt.%), Sr (954-2190 ppm), Sr/Y (68-132) and La/Yb (53-85), and low Y and Yb contents. The Nangqian felsic intrusions have high initial 87Sr/86Sr (0.7050-0.7055), variable εNd(t) (- 0.31-1.43) and small variations in (206Pb/204Pb)i (18.68-18.74), (207Pb/204Pb)i (15.53-15.62) and (208Pb/204Pb)i (38.51-38.80). Zircon crystals from both syenite and monzonite porphyries are characterized by positive εHf(t) from 5.2 to 8.5. The results suggest that the syenite and monzonite magmas were differentiated from parental shoshonitic melts by fractional crystallization of olivine, clinopyroxene and minor feldspar. The parent magmas originated from a lithospheric mantle metasomatized by slab

  5. Seaweed composition from Bintulu coast of Sarawak, Malaysia.

    PubMed

    Zawawi, Mohd Hafizbillah; Idris, Mohd Hanafi; Kamal, Abu Hena Mustafa; King, Wong Sing

    2014-08-01

    Species composition of seaweed and distribution were investigated in the coastal waters of Bintulu, Sarawak. The seaweed samples were collected during low tide between May 2011 and May 2012 from the six different stations. In total 54 species of seaweeds were identified from study areas of Bintulu coastal waters. Among them, 23 species were from Rhodophyta with 11 families, 15 species were from Phaeophyta with 2 families and 16 species were from Chlorophyta with 10 families: Seventeen species of seaweeds were recorded from the Tanjung Batu, while 23 species from Pantai Telekom, 14 species from Golden Beach, 26 species from Kuala Similajau, 12 species from Kuala Nyalau and 21 species from Batu Mandi. Seaweeds abundance was high in rocky substrate and Rhodophyta (11 families and 23 species) was the common and highest group of seaweeds in this coastal areas. Present study recorded high diversified seaweed species at the rocky shore area compare to reef area.

  6. Diversity of hydrothermal processes and different types of epithermal deposits

    NASA Astrophysics Data System (ADS)

    Sidorov, A. A.; Volkov, A. V.

    2016-05-01

    It is shown that classical epithermal deposits with hydrothermal explosions, brecciated and framework-lamellar (including agate-like) structures, and well-developed bonanzas are usually pre-porphyry in origin. This inference seems to be important for development of the genetic model of a porphyry-epithermal ore-forming system as well as for exploration of gold-silver deposits and assessment of their potential.

  7. Geological Structure of the Semipalatinsk Region,

    DTIC Science & Technology

    1987-08-10

    are acid, the younger they are. In this complex they are included: the I phase - gabbro, quartz gabbro, diorite, syenite and syenite -diorites; the II...trondhjemites and fine-grained porphyritic granites. The veins/strands of granite-porphyries, granodioritoporphyries, syenite -porphyries, granotsyenite...quartz syenite , less DOC - 87068900 PAGE 41 frequently, syenites ; II phase - coarse-grained or large- prophyricide alkaline granites, sometimes with

  8. Gold deposits in the late Archaean Nzega-Igunga greenstone belt, central plateau of tanzania

    SciTech Connect

    Feiss, P.G.; Siyomana, S.

    1985-01-01

    2.2 m oz of gold have been produced, since 1935, from late Archaean (2480-2740 Ma) greenstone belts of the Central Plateau, Tanzania. North and east of Nzega (4/sup 0/12'S, 3/sup 0/11'E), 18% of the exposed basement, mainly Dodoman schists and granites, consists of metavolcanics and metasediments of the Nyanzian and Kavirondian Series. Four styles of mineralization are observed. 1. Stratabound quartz-gold veins with minor sulfides. Host rocks are quartz porphyry, banded iron formation (BIF), magnetite quartzite, and dense, cherty jasperite at the Sekenke and Canuck mines. The Canuck veins are on strike from BIF's in quartz-eye porphyry of the Igusule Hills. 2. Stratabound, disseminated gold in coarse-grained, crowded feldspar porphyry with lithic fragments and minor pyrite. At Bulangamilwa, the porphyry is conformable with Nyanzian-aged submarine (.) greenstone, volcanic sediment, felsic volcanics, and sericite phyllite. The deposits are on strike with BIF of the Wella Hills, which contains massive sulfide with up to 15% Pb+Zn. 3. Disseminated gold in quartz-albite metasomes in Nyanzian greenstones. At Kirondatal, alteration is associated with alaskites and feldspar porphyry dikes traceable several hundred meters into post-Dodoman diorite porphyry. Gold is with pyrite, arsenopyrite, pyrrhotite, minor chalcopyrite, and sphalerite as well as tourmalinite and silica-cemented breccias. 4. Basal Kavirondian placers in metaconglomerates containing cobbles and boulders of Dodoman and Nyanzian rocks several hundred meters up-section from the stratabound, disseminated mineralization at Bulangamilwa.

  9. Geology and ore deposits of the Chicago Creek area, Clear Creek County, Colorado

    USGS Publications Warehouse

    Harrison, J.E.; Wells, J.D.

    1956-01-01

    The Chicago Creek area, Clear Creek County, Colo., forms part of the Front Range mineral belt, which is a northeast-trending belt of coextensive porphyry intrusive rocks and hydrothermal veins of Tertiary age. More than $4.5 million worth of gold, silver, copper, lead, zinc, and uranium was produced from the mines in the area between 1859 and 1954. This investigation was made by the Geological survey on behalf of the Division of Raw Materials of the U.S. Atomic Energy Commission. The bedrock in the area is Precambrian and consists of igneous rocks, some of which have been metamorphosed , and metasedimentary rocks. The metasedimentary rocks include biotite-quartz-plagioclase gneiss that is locally garnetiferous, sillimanitic biotite-quartz gneiss, amphibolite, and lime-silicate gneiss. Rocks that may be metasedimentary or meta-igneous are quartz monzonite gneiss and granite gneiss and pegmatite. The granite gneiss and pegmatite locally form a migmatite with the biotitic metasedimentary rocks. These older rocks have been intruded by granodiorite, quartz, and granite pegmatite. During Tertiary time the Precambrian rocks were invaded by dikes and plugs of quartz monzonite porphyry, alaskite porphyry, granite porphyry, monzonite porphyry, bostonite and garnetiferous bostonite porphyry, quartz bostonite porphyry, trachytic granite porphyry, and biotite-quartz latite-porphyry. Solifluction debris of Wisconsin age forms sheets filling some of the high basins, covering some of the steep slopes, and filling parts of some of the valleys; talus and talus slides of Wisconsin age rest of or are mixed with solifluction debris in some of the high basins. Recent and/or Pleistocene alluvium is present along valley flats of the larger streams and gulches. Two periods of Precambrian folding can be recognized in the area. The older folding crumpled the metasedimentary rocks into a series of upright and overturned north-northeast plunging anticlines and synclines. Quartz monzonite

  10. Notes on interpretation of geophysical data over areas of mineralization in Afghanistan

    USGS Publications Warehouse

    Drenth, Benjamin J.

    2011-01-01

    Afghanistan has the potential to contain substantial metallic mineral resources. Although valuable mineral deposits have been identified, much of the country's potential remains unknown. Geophysical surveys, particularly those conducted from airborne platforms, are a well-accepted and cost-effective method for obtaining information on the geological setting of a given area. This report summarizes interpretive findings from various geophysical surveys over selected mineral targets in Afghanistan, highlighting what existing data tell us. These interpretations are mainly qualitative in nature, because of the low resolution of available geophysical data. Geophysical data and simple interpretations are included for these six areas and deposit types: (1) Aynak: Sedimentary-hosted copper; (2) Zarkashan: Porphyry copper; (3) Kundalan: Porphyry copper; (4) Dusar Shaida: Volcanic-hosted massive sulphide; (5) Khanneshin: Carbonatite-hosted rare earth element; and (6) Chagai Hills: Porphyry copper.

  11. Cambrian-Ordovician magmatism in the Thiel Mountains, Transantarctic Mountains, and implications for the Beardmore orogeny

    NASA Astrophysics Data System (ADS)

    Pankhurst, R. J.; Storey, B. C.; Millar, I. L.; MacDonald, D. I. M.; Vennum, W. R.

    1988-03-01

    New field and laboratory studies result in a redefinition of the three main lithostratigraphic units of the Thiel Mountains. These are (1) the Thiel Mountains porphyry, a massive hypersthene-bearing monzonite, faulted against (2) the Mount Walcott Formation, a sequence of shallow-water volcaniclastic sedimentary rocks and dacitic tuffs or flows, and (3) the Reed Ridge granites, coarse-grained biotite granite/granodiorite stocks that cut the porphyry. Genetic relations between the porphyry and both the sedimentary rocks and the granite are proposed. Evidence for a Phanerozoic age indicated by the presence of fossils in the sediments is reinforced by Rb-Sr whole-rock dating that has conclusively established a Late Cambrian or Early Ordovician age (502 ±5 Ma) for the entire sequence. The stratigraphic and tectonic consequences refute all evidence for magmatism in the Transantarctic Mountains associated with the Precambrian "Beardmore orogeny," the age and status of which are now in doubt.

  12. Geophysical ore guides along the Colorado mineral belt

    USGS Publications Warehouse

    Case, James E.

    1967-01-01

    A 40-50-mgal gravity low trends northeast along the Colorado mineral belt between Monarch Pass and Breckenridge, Colorado. The low is probably caused by a silicic Tertiary batholith of lower density than adjacent Precambrian crystalline rocks. Many major mining districts associated with silicic Tertiary intrusives are near the axis of the low. Positive and negative aeromagnetic anomalies are present over the larger silicic Tertiary intrusive bodies. A good correlation exists between the magnetic lows and zones of altered, mineralized porphyry. Apparently, original magnetite in the silicic porphyries has been altered to relatively nonmagnetic pyrite or iron oxides. The regional gravity low aids in defining the limits of the mineral belt, and the magnetic lows over the porphyries indicate specific alteration zones and the possibility of associated mineral deposits.

  13. Geologic map of the Ahankashan-Rakhna basin, Badghis, Ghor, and Herat Provinces, Afghanistan, modified from the 1974 original map compilation of Y.I. Shcherbina and others

    USGS Publications Warehouse

    Tucker, Robert D.; Stettner, Will R.; Masonic, Linda M.; Bogdanow, Anya K.

    2014-01-01

    The Ahankashan and Rakhna prospect area is one of several gold and copper deposits within west-central Afghanistan. Here, various felsic to intermediate igneous porphyries intrude Lower Triassic to lower Paleogene sedimentary rocks, producing mineral and ore-bearing zones related to hydrothermal alteration, skarns, silicification, and crushing (brecciation). Mineralized skarns contain assemblages such as magnetite, magnetite-hematite, epidote-hematite, and epidote-garnet, as well as disseminations of chalcopyrite, covellite, chalcocite, cuprite, malachite, and azurite. Gold mineralization is mainly associated with zones of crushing along faults, and with small silicified igneous veins within granite and quartz porphyry.

  14. Petrologic, tectonic, and metallogenic evolution of the southern segment of the ancestral Cascades magmatic arc, California and Nevada

    USGS Publications Warehouse

    du Bray, Edward A.; John, David A.; Cousens, Brian L.

    2013-01-01

    Although rocks in the two arc segments have similar metal abundances, they are metallogenically distinct. Small porphyry copper deposits are characteristic of the northern segment whereas significant epithermal precious metal deposits are most commonly associated with the southern segment. These metallogenic differences are also fundamentally linked to the tectonic settings and crustal regimes within which these two arc segments evolved.

  15. The california poppy (eschscholtzia mexicana) as a copper indicator plant - a new example

    USGS Publications Warehouse

    Chaffee, M.A.; Gale, C.W.

    1976-01-01

    The abundance and distribution of the California poppy (Eschscholtzia mexicana) correlates closely with the copper-rich outcrop of a small porphyry-type deposit in Arizona. Chemical factors are probably more important than physical factors in determining why this species is sometimes found as a copper indicator plant. ?? 1976.

  16. Geochemistry of sericite and chlorite in well 14-2 Roosevelt Hot Springs geothermal system and in mineralized hydrothermal systems

    SciTech Connect

    Ballantyne, J.M.

    1980-06-01

    Chemical compositions of chlorite and sericite from one production well in the Roosevelt geothermal system have been determined by electron probe methods and compared with compositions of chlorite and sericite from porphyry copper deposits. Modern system sericite and chlorite occur over a depth interval of 2 km and a temperature interval of 250/sup 0/C.

  17. Rhenium: a rare metal critical in modern transportation

    USGS Publications Warehouse

    John, David A.

    2015-01-01

    Rhenium rarely occurs as a native element or as its own sulfide mineral—rheniite (ReS2)—and often occurs as a substitute for molybdenum in molybdenite (MoS2). Most extracted rhenium is a byproduct of copper mining, with about 80 percent recovered from flue dust during the processing of molybdenite concentrates from porphyry copper deposits.

  18. Petrogenesis of the Seleteguole granitoids from Jinhe county in Xinjiang (West China): Implications for the tectonic transformation of Northwest Tianshan

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Leng, Cheng-Biao; Zhang, Xing-Chun; Su, Wen-Chao; Tang, Hong-Feng; Yan, Jia-Hui; Cao, Jing-Liang

    2016-07-01

    The Seleteguole Cu-Mo deposit in Jinghe County, Xinjiang is tectonically located on the northern margin of the Northwestern Tianshan. Three major intrusions including biotite granite, diorite porphyry and quartz diorite porphyry have been identified. The biotite granite, with a zircon U-Pb age of 307 ± 3 Ma, intruded carbonates and clastic rocks of the Middle Carboniferous Dongtujin Formation. The younger diorite porphyry and quartz diorite porphyry, with an identical zircon U-Pb age of 302 ± 3 Ma, locally intruded the biotite granite; where the granite in contact with the two porphyries were characterized by phyllic alteration. The mineralogical and geochemical characteristics indicate that all granitoids in Seleteguole belong to calc-alkaline I-type. These granitoids are enriched in LILE relative to HFSE with negative anomalies of Nb, P and Ti, typical of arc-related rocks. All three granitoids have positive zircon εHf(t) values, low Mg# ratios (34-39), and low Cr (< 60 ppm) and Ni (< 15 ppm) contents, suggesting that their parental magmas could be derived from juvenile lower crust that has probably originated from cooling of mantle-derived magmas as a result of the subduction of Paleo-Junggar Ocean beneath the Yili Block. Subducted sediments were involved in the source of the granitoids in Seleteguole. Compared to biotite granite, diorite porphyry and quartz diorite porphyry have higher Th/La ratios but lower zircon εHf(t) values, indicating that more subducted sediments contributed in the latter two. The regional geological and geochemical characteristics of the Late Carboniferous igneous rocks in the Northwestern Tianshan show that Late Carboniferous I-type granitoids, with juvenile Sr-Nd-(Hf) isotopic signatures, formed in a continent-marginal arc setting as a result of the subduction of Paleo-Junggar Ocean beneath the Yili Block. In combination with the compositions of the Early Permian granitoids in the region, we suggest that the tectonic setting of

  19. Oil-productive Miocene algal and sea grass carbonate mudbanks, south Sumatra, Indonesia

    SciTech Connect

    Longman, M.W.; Beddoes, L.R. Jr.

    1985-02-01

    Ramba and Tanjung Laban oil fields, located about 70 km northwest of Palembang in southern Sumatra, produce from wackestones and packstones in the lower Miocene Batu Raja Formation. Reservoir rocks are part of relatively small, undolomitized, low-relief carbonate buildups that accumulated on a widespread platform facies. Rocks in the platform facies are dominantly shaly nodular wackestones, whereas rocks in the buildup are dominantly nonshaly wackestones and packstones. The regional setting, the abundance of micrite in the buildups, the absence of both coralline algae and marine cements, and the geometry of the buildups suggest that noncalcareous algae and/or sea grasses were the dominant organisms responsible for forming these mudbanks. The absence of shale in the mudbanks has been important in forming the secondary porosity that yields most of the oil. Vugs and molds form as much as 30% of the rock in the best reservoir zones. Fractures formed by dissolution and collapse greatly enhance reservoir zones quality in many places. Another type of porosity, microintercrystalline, occurs within chalky micrites scattered through the upper part of the buildups. Porosity in these micrites reaches 25%, but permeability is very low. The recent discovery of oil in these low-energy carbonate mudbanks of the Batu Raja Formation has opened a new exploration play in the South Sumatra basin. Many similar buildups will likely be found as exploration continues and the basin's paleogeography becomes better understood.

  20. Ecology of ephemeroptera, plecoptera and trichoptera (insecta) in rivers of the gunung jerai forest reserve: diversity and distribution of functional feeding groups.

    PubMed

    Hamid, Suhaila Ab; Md Rawi, Che Salmah

    2014-08-01

    A field study was performed to describe the functional feeding groups (FFGs) of Ephemeroptera, Plecoptera and Trichoptera (EPT) in the Tupah, Batu Hampar and Teroi Rivers in the Gunung Jerai Forest Reserve (GJFR), Kedah, Malaysia. Twenty-nine genera belonging to 19 families were identified. The EPTs were classified into five FFGs: collector-gatherers (CG), collector-filterers (CF), shredders (SH), scrapers (SC) and predators (P). In this study, CG and CF were the dominant groups inhabiting all three rivers. Ephemeroptera dominated these rivers due to their high abundance, and they were also the CG (90.6%). SC were the lowest in abundance among all groups. Based on the FFGs, the Teroi River was suitable for CG, whereas the Tupah and Batu Hampar Rivers were suitable for CG and CF. The distribution of FFGs differed among the rivers (CG, χ(2) = 23.6, p = 0.00; SH, χ(2) = 10.02, p = 0.007; P, χ(2) = 25.54, p = 0.00; CF, χ(2) = 21.95, p = 0.00; SC, χ(2) = 9.31, p = 0.01). These findings indicated that the FFGs found in rivers of the GJFR represent high river quality.

  1. Ecology of Ephemeroptera, Plecoptera and Trichoptera (Insecta) in Rivers of the Gunung Jerai Forest Reserve: Diversity and Distribution of Functional Feeding Groups

    PubMed Central

    Hamid, Suhaila Ab; Md Rawi, Che Salmah

    2014-01-01

    A field study was performed to describe the functional feeding groups (FFGs) of Ephemeroptera, Plecoptera and Trichoptera (EPT) in the Tupah, Batu Hampar and Teroi Rivers in the Gunung Jerai Forest Reserve (GJFR), Kedah, Malaysia. Twenty-nine genera belonging to 19 families were identified. The EPTs were classified into five FFGs: collector-gatherers (CG), collector-filterers (CF), shredders (SH), scrapers (SC) and predators (P). In this study, CG and CF were the dominant groups inhabiting all three rivers. Ephemeroptera dominated these rivers due to their high abundance, and they were also the CG (90.6%). SC were the lowest in abundance among all groups. Based on the FFGs, the Teroi River was suitable for CG, whereas the Tupah and Batu Hampar Rivers were suitable for CG and CF. The distribution of FFGs differed among the rivers (CG, χ2 = 23.6, p = 0.00; SH, χ2 = 10.02, p = 0.007; P, χ2 = 25.54, p = 0.00; CF, χ2 = 21.95, p = 0.00; SC, χ2 = 9.31, p = 0.01). These findings indicated that the FFGs found in rivers of the GJFR represent high river quality. PMID:25210588

  2. Vertical structure of a caldera-filling pyroclastics and post-caldera granitic sill: the Middle Miocene Kumano Acidic Rocks emplaced in the Paleogene Shimanto accretionary complex, Japan

    NASA Astrophysics Data System (ADS)

    Nakajima, T.; Geshi, N.; Oikawa, T.; Shinjoe, H.; Miura, D.; Koizumi, N.

    2009-04-01

    A 600m all-core drilling penetrated a volcano-plutonic complex associated with middle Miocene Kumano caldera, Kii Peninsula, Southwest Japan. It shows us the vertical cross section of the caldera-filling pyroclastic deposit and granitic sill intruded inside the caldera. The drilling site is located in the southern rim of the north body of Kumano igneous complex. The drilling core consists of the granite porphyry intrusion (Kumano Granite Porphyry) in the upper part (from surface to 464.3 m depth) and the welded tuff (Owase-Shirahama Pyroclastic Rocks) beneath them (464.3 and 600 m depth), which are associated with the caldera formation. The welded tuff in the core sample consists mainly of well-sorted coarse-grained volcanic ash of crystal fragments and lithic fragments. Subordinate amount of pumice fragment more than 10 cm across are scattered. Though most part of the welded tuff in the core sample is massive as observed in the surface outcrops, some parts show remarkable bedding structure. These structural characters suggest that the welded tuff is a pile of many flow units with several 10s meters thick each, which consists of basal pumice-concentrated bed, main massive tuff, and upper bedding part. The lower intrusion boundary of the Kumano Granite Porphyry is exposed at 464.3 m deep, where the granite porphyry intrudes into the host welded tuff with about 10 m thick chilled margin, in which the granite porphyry has very-fine groundmass. The groundmass texture of the granite porphyry shows systematic variation with the distance from the intrusion contact. Within about 20 m from the contact, the groundmass consists of very-fine crystals and entirely shows volcanic rock texture. For 150 m above them, the groundmass consists mainly of quartz and plagioclase and shows equigranular texture. In the upper part (less than 300m deep), the groundmass shows graphic texture with quartz and alkali feldspar. The vertical variation of the groundmass texture indicates upward

  3. Permian magmatic sequences of the Bilihe gold deposit in central Inner Mongolia, China: Petrogenesis and tectonic significance

    NASA Astrophysics Data System (ADS)

    Liu, Chunhua; Nie, Fengjun

    2015-08-01

    The Bilihe gold deposit is located in the eastern section of the Ondor Sum-Yanji Suture at the southern margin of the Xing'an-Mongolian Orogenic Belt (XMOB) and the northern margin of the North China Craton (NCC), central Inner Mongolia. The magmatic rocks in the ore district are generally high-K calc-alkaline, enriched in LREE, Zr, and Hf, and depleted in HREE, Nb, Ta, and P. The magmatic evolution sequences are norite gabbro → granodiorite porphyry → granite or norite gabbro → andesite → dacite porphyry → granodiorite, which show a trend of decreasing TiO2, FeO, MgO, CaO, and P2O5 with increasing SiO2. In the Bilihe ore district, hydrothermal processes were coeval with granitic magmatism for a period of ~ 17 Myr (272-255 Ma). The ages of the granite, granodiorite porphyry, granodiorite, and dacite porphyry are 271.5-264.1 Ma, 269.8-255.8 Ma, 268.3 Ma, and 268.6-259.4 Ma, respectively. The magmatic rocks contain magmatic, hydrothermal, and magmatic-hydrothermal zircons. The magmatic zircons have δCe > 4, La < 3 ppm, and SmN/LaN > 2.5; the hydrothermal zircons have δCe < 4, La > 3 ppm, and SmN/LaN < 2.5. The Nb/Ta and Zr/Hf ratios of granodiorite are 12.7-14.99 and 40.2-46.56, respectively. The Zr/Hf ratios successively increase in the sequence of granite (27.4-29.02) → granodiorite porphyry (29.19-32.18) → dacite porphyry (33.54-38.5) → norite gabbro (36.75-38.37), and their Nb/Ta ratios are 9.09-12.38. Zircons in granodiorite yield ε Hf (t) values of - 0.29 to - 56 (n = 13) and 2.07-7.62 (n = 5), and they give a Hf two-stage model age (tDM2) of 807-4765 Ma. The ε Hf (t) values of the zircons in granite, granodiorite porphyry, and dacite porphyry are - 0.46 to 8.03, 3.17 to 10.32, and - 0.78 to 6.58, respectively, and their Hf tDM2 ages are 787-1324 Ma, 638-1091 Ma, and 868-1343 Ma, respectively. Dehydration partial melting of subducted oceanic crust resulted in the formation of dacite porphyry; partial melting of depleted mantle resulted in

  4. Subeffusive Ejecta At Mount Vesuvius: Evidence For A "shallow" Magma Reservoir

    NASA Astrophysics Data System (ADS)

    Cigolini, C.; Ruffini, R.; Laiolo, M.

    Subeffusive ejecta of the 1944 eruption of Mount Vesuvius are tephritic clinopyroxene-rich porphyries and italites. These materials are associated to pyroclas- tic deposits of phono-tephritic composition. Tephrytic porphyries show a hypidiomor- phic granular texture and consist of phenocrystic leucite, diopsidic clinopyroxene, olivine and phlogopite on a holocrystalline matrix of leucite, plagioclase, phlogopite. Titanomagnetite and apatite are accessory phases. Sampled italites ejecta are charac- terized by an orthocumulithic texture consisting of a crystals leucite and interstitial brownish glass. This glass includes rare elongated microphenocrysts of plagioclase and subordinated clinopyroxene. REE patterns for the tephritic porphyries are com- parable with those of recent lavas and tephra and show a sligthly higher enrichment in HREE (up to 10 times the average chondrite). Spider diagrams, normalized to pri- mordial mantle values, indicate that the tephritic porphyries lack a negative anomaly in Ta which, in turn, is strongly negative within the lavas. This is due to the higher content of phenocrystic clinopyroxene (with a high mineral/melt partition coefficient) within the tephritic porphyries. Thermobarometric estimates indicate that leucite is in equilibrium with a tephritic melt at pressures of 5.7-6 kbar for temperatures ranging 1100-1200 C. Moreover, selected reactions for the assemblage Ol+Cpx+An+SiO2 (liq) define equilibrium pressures of 3.2-5 kbar [both for hydrous (with about 2 wt % H2O) and anhydrous conditions] for temperatures ranging 1150-1200 C. These esti- mates suggests the existence of a secondary "shallow" reservoir located at a depth of about 10-18 Km below Mount Vesuvius, which is consistent with recent petrological and geophysical data.

  5. Geochronology, Geochemistry and Petrogenesis of the Intermediate and Acid Dykes in Linzhou Basin, Southern Tibet

    NASA Astrophysics Data System (ADS)

    Dong, M.; Zhao, Z.; Zhu, D. C.; Dong, G.; Mo, X.

    2015-12-01

    The Linzizong volcanic succession (also called Linzizong Group, ~65-45 Ma), which occurred in southern Gangdese magmatic belt in response to the collision processes between India and Eurasia continents, have been well studied in the Linzhou Basin, to the northeast of Lhasa. Our research obtains some new results of zircon U-Pb, Hf isotopic data, and whole rock major and trace elements geochemical data of the intermediate (diorite porphyry) to acid (granite porphyry) dykes intruded into the Linzizong volcanics in Linzhou Basin. These dykes intruded into Dianzhong and Nianbo formations of Linzizong Group. All the samples are sub-alkaline, varying from calc-alkaline to high-K calc-alkaline series. They are peraluminous (A/CNK>1.1). The diorite porphyry, intruded in 62.4Ma with positive zircon Hf isotopes (ɛHf(t)=+5.1~+7.6), have similar composition to the andesitic rocks from Dianzhong Formation. The granite porphyries, intruded between 55.1Ma and 61.1Ma, with ɛHf(t) ranging from -1.1 to +10.4, have comparable composition with the rhyolitic Nianbo Formation. A series of evidences, including: (1) the samples have positive, mantle-like Hf feature (average ɛHf(t)=+5.9 of 86 samples); (2) wide-range variation of ɛHf(t) in samples (3.5~8.8 ɛ units in the four granite porphyries), which implying an inhomogeneous source regions; (3) magma-mixing trend in the plots of FeOT against MgO, suggesting that the magma-mixing processes that have taken place in the southern Gangdese belt, can also be applied to explain the origin of these dykes in Linzhou Basin. The dykes intruded coeval or shortly later than their equivalent volcanic rocks (Dianzhong and Nianbo formations), are in the transitional settings from subduction of Tethyan oceanic crust to the collisional between India and Eurasia continents.

  6. Geochemistry, zircon U-Pb and Lu-Hf isotopes of an Early Cretaceous intrusive suite in northeastern Jiangxi Province, South China Block: Implications for petrogenesis, crust/mantle interactions and geodynamic processes

    NASA Astrophysics Data System (ADS)

    Deng, Zhengbin; Liu, Shuwen; Zhang, Lifei; Wang, Zongqi; Wang, Wei; Yang, Pengtao; Luo, Ping; Guo, Boran

    2014-07-01

    The Early Cretaceous Tieshan intrusive suite, in northeastern Jiangxi Province along the northern margin of the Eastern Cathaysia Block, is composed of diabase porphyrites, monzodiorites, syenite porphyries, quartz monzonites, monzogranites and granite porphyries. LA-ICPMS zircon U-Pb isotopic analyses reveal that this intrusive complex was emplaced between 142 Ma and 117 Ma. The ~ 135 Ma diabase porphyrites, monzodiorites, and syenite porphyries are characterized by low to moderate SiO2 and MgO contents, with high K2O and total alkaline contents. These rocks exhibit slightly to strongly fractionated REE patterns and upper crust-like multi-element patterns with depletions of Nb, Ta and Ti, and show strongly negative εHf (t) values of - 9.0 to - 11.8. All these patterns are identical to those of the Caiyuan syenites, Huangtuling gabbros in the east, and Lengshuikeng trachyandesites and quartz syenites in the west. These geochemical and zircon Lu-Hf isotopic features indicate that their magmatic precursors were generated by 0.2%-2% partial melting of a phlogopite-bearing enriched subcontinental lithospheric mantle source that was metasomatized by sediments. The ~ 117 Ma quartz monzonite has slightly higher εHf (t) values (- 5.6 to - 8.7) like those of the Honggong syenites, indicating an interaction between the asthenosphere and the lithosphere. The ~ 142-134 Ma granite porphyries and monzogranites are characterized by high SiO2 levels but low concentrations of refractory elements, and show enrichment of LREEs and LILEs, with variable negative anomalies of Nb, Ta, Ti, Sr, P and Ba in multi-element diagrams normalized by primitive mantle. The monzogranite exhibits strongly negative εHf (t) values of - 10.5 to - 13.3 and TDM2 (Hf) values of 1849-2023 Ma, and the granite porphyries display relatively wide εHf (t) values of - 7.2 to - 13.4 and TDM2 (Hf) values of 1645-2043 Ma, indicating that these monzogranites and granite porphyries are highly fractionated granites

  7. U-Pb, Re-Os and Ar-Ar dating of the Linghou polymetallic deposit, Southeastern China: Implications for metallogenesis of the Qingzhou-Hangzhou metallogenic belt

    NASA Astrophysics Data System (ADS)

    Tang, Yanwen; Xie, Yuling; Liu, Liang; Lan, Tingguan; Yang, Jianling; Sebastien, Meffre; Yin, Rongchao; Liang, Songsong; Zhou, Limin

    2017-04-01

    The Qingzhou-Hangzhou metallogenic belt (QHMB) in Southeastern China has gained increasingly attention in recent years. However, due to the lack of reliable ages on intrusions and associated deposits in this belt, the tectonic setting and metallogenesis of the QHMB have not been well understood. The Linghou polymetallic deposit in northwestern Zhejiang Province is one of the typical deposits of the QHMB. According to the field relationships, this deposit consists of the early Cu-Au-Ag and the late Pb-Zn-Cu mineralization stages. Molybdenite samples with a mineral assemblage of molybdenite-chalcopyrite-pyrite ± quartz are collected from the copper mining tunnel near the Cu-Au-Ag ore bodies. Six molybdenite samples give the Re-Os model ages varying from 160.3 to 164.1 Ma and yield a mean age of 162.2 ± 1.4 Ma for the Cu-Au-Ag mineralization. Hydrothermal muscovite gives a well-defined Ar-Ar isochron age of 160.2 ± 1.1 Ma for the Pb-Zn-Cu mineralization. Three phases of granodioritic porphyry have been distinguished in this deposit, and LA-ICP-MS zircon U-Pb dating shows that they have formed at 158.8 ± 2.4 Ma, 158.3 ± 1.9 Ma and 160.6 ± 2.1 Ma, comparable to the obtained ages of the Cu-Au-Ag and Pb-Zn-Cu mineralization. Therefore, these intrusive rocks have a close temporal and spatial relationship with the Cu-Au-Ag and Pb-Zn-Cu ore bodies. The presences of skarn minerals (e.g., garnet) and vein-type ores, together with the previous fluid inclusion and H-O-C-S-Pb isotopic data, clearly indicate that the Cu-Au-Ag and Pb-Zn-Cu mineralization are genetically related to these granodiorite porphyries. This conclusion excludes the possibility that this deposit is of ;SEDEX; type and formed in a sag basin of continental rifts setting as previously proposed. Instead, it is proposed that the Linghou polymetallic and other similar deposits in the QHMB, such as the 150-160 Ma Yongping porphyry-skarn Cu-Mo, Dongxiang porphyry? Cu, Shuikoushan/Kangjiawang skarn Pb

  8. Geochemistry, zircon U-Pb dating and Hf isotopies composition of Paleozoic granitoids in Jinchuan, NW China: Constraints on their petrogenesis, source characteristics and tectonic implication

    NASA Astrophysics Data System (ADS)

    Zeng, Renyu; Lai, Jianqing; Mao, Xiancheng; Li, Bin; Ju, Peijiao; Tao, Shilong

    2016-05-01

    Granitoids are widely distributed in Jinchuan at the southwestern margin of the North China plate, which is also an important area of mineral deposits. The research subject of this article are two Paleozoic granitoids, a cataclastic syenogranite and a granodiorite porphyry. This study presents whole rock geochemistry and zircon U-Pb-Hf isotope data for the two granitoids to determine their petrogenesis, source characteristics and tectonic significance. The cataclastic syenogranite is characterized by metaluminous composition with high potassium, and LaN/YbN from 39 to 48. The composition with strong negative Eu anomalies and Zircon saturation temperatures (TZr) from 947 to 1072 °C classify this intrusion as an A-type granite. The granodiorite porphyry is metaluminous with high sodium, sub-alkaline, LaN/YbN ratios from 27 to 32. These I-type intrusions have no Eu anomalies and TZr ranges from 818 to 845 °C. Both the cataclastic syenogranite and granodiorite porphyry show enrichment of LREE and LILE and depletion of HREE and HFSE, except Hf and Zr. Using single zircon LA-ICP-MS U-Pb dating, the emplacement age of the cataclastic syenogranite and granodiorite porphyry are determined at 433.4 ± 3.7 Ma and 361.7 ± 4.6 Ma, respectively. Zircons from the cataclastic syenogranits have uniform negative εHf(t) values (-11 ± 0.5 to -9 ± 0.5), implying the involvement of an old Palaeoproterozoic crustal source in magma genesis. The zircons from the granodiorite porphyry have εHf(t) values that range from -8 ± 1.0 to +10 ± 0.6, suggesting heterogeneous source materials involving both juvenile and ancient crust reworked crustal components. Based on the geological significance of granites at the southwestern margin of the North China plate, the closure of the North Qilian Ocean occurred at ∼444 Ma. Geochemical features suggest that the cataclastic syenogranite and granodiorite porphyry formed in an intraplate extensional and compressional setting, respectively. Hence

  9. Fluorspar deposits of Utah

    USGS Publications Warehouse

    Thurston, W.R.; Staatz, M.H.; Cox, D.C.

    1954-01-01

    The studies of fluorspar localities in Utah made by the U. S. Geological Survey during and since the recent war are summarized. The fluorspar at the Cougar Spar and Blue Bell mines in the Indian Peak Range of western Beaver County occurs as fissure veins in fault and breccia zones in volcanic and intrusive rocks. At the Monarch (Staats) claims in west-central Beaver County fluorspar was mined chiefly from a fault between limestone and rhyolite porphyry. The Thomas Range district in Juab County has yielded sizeable tonnages of fluorspar from pipes in faulted dolomite and rhyolite porphyry. From 1918 to 1924 the Silver Queen mine in Tooele County produced fluorspar from flssure veins in faulted limestone. The report describes the geology of producing mines and the various prospects examined. Production and reserves of fluorspar for Utah are summarized.

  10. The giant Pebble Cu-Au-Mo deposit and surrounding region, southwest Alaska: introduction

    USGS Publications Warehouse

    Kelley, Karen D.; Lang, James R.; Eppinger, Robert G.

    2013-01-01

    The Pebble deposit is located about 320 km southwest of and 27 km northwest of the village of Iliamna in Alaska (Fig. 1A). It is one of the largest porphyry deposits in terms of contained Cu (Fig. 2A) and it has the largest Au endowment of any porphyry deposit in the world (Fig. 2B). The deposit comprises the Pebble West and Pebble East zones that represent two coeval hydrothermal centers within a single system (Lang et al., 2013). Together the measured and indicated resources total 5,942 million metric tons (Mt) at 0.42% Cu, 0.35 g/t Au, and 250 ppm Mo with an inferred resource of 4,835 Mt at 0.24% Cu, 0.26 g/t Au, and 215 ppm Mo. In addition, the deposit contains significant concentrations of Ag, Pd, and Re (Northern Dynasty Minerals, 2011).

  11. Integration and analysis of airborne geophysical data of the Darrehzar area, Kerman Province, Iran, using principal component analysis

    NASA Astrophysics Data System (ADS)

    Ranjbar, H.; Hassanzadeh, H.; Torabi, M.; Ilaghi, O.

    2001-08-01

    This paper describes a methodology for the integrated interpretation of airborne magnetic and airborne γ-ray spectrometer data. The Darrehzar porphyry copper deposit is situated in the Urumieh-Dokhtar magmatic assemblage of Central Iran. Phyllic and propylitic alterations are pervasive in the area but potassic and argillic alterations are not readily recognized on the surface. The spatial distributions of geophysical data resemble the lithological and alteration patterns in the area. The Darrehzar porphyry copper deposit is considered as a control site for determination of the degrees that the geophysical data is correlated with the mineralization zone. Airborne magnetic/radiometric, and geochemical/alteration data sets have been integrated and analyzed using principal component analysis. This technique is found to be useful for the delineation of hydrothermally altered areas and data compression.

  12. Stratigraphic development and hydrothermal activity in the central western Cascade Range, Oregon

    SciTech Connect

    Cummings, M.L.; Bull, M.K. ); Pollock, J.M. ); Thompson, G.D. )

    1990-11-10

    Two volcanic sequences bounded by erosional unconformities compose the stratigraphy of the North Santiam mining district, Western Cascade Range, Oregon. Diorite, grandodiorite, and leucocratic quartz porphyry dikes, stocks, and sills intrude the breccias, flows, and tuffs of a volcanic center in the older Sardine Formation. Tourmaline-bearing breccia pipes are associated with the porphyritic granodiorite intrusions. An erosional unconformity separates the Sardine Formation from the overlying Elk Lake formation. The alteration patterns in the two formations are consistent with the development of hydrothermal systems during the eruption of each formation. However, the development of the two hydrothermal systems is separated by a period of erosion of the older volcanic pile. Early formation of mineralization that resembles porphyry copper deposits occurred within the Sardine Formation, and later, after eruption of the Elk Lake formation, epithermal veins and alteration developed along faults, fractures, and the margins of dikes in the Sardine Formation.

  13. SHRIMP and 40Ar/39Ar age constraints for timing of plutonism and mineralization in the Boulder batholith

    USGS Publications Warehouse

    Lund, K.D.; Aleinikoff, John N.; Kunk, Michael J.; Unruh, Dan M.; Zeihen, G.D.; Hodges, W.C.; du Bray, Edward A.; O'Neill, J Michael

    2002-01-01

    The 66 Ma age for the quartz monzodiorite of Boulder Baldy and consideration of previous dating studies in the region indicate that small ca. 66 Ma plutonic systems may be common in the Boulder batholith region and especially to the east. The approximately 64 Ma porphyry copper systems at Butte and gold mineralization at Miller Mountain are indicative of regionally important mineralizing systems of this age in the Boulder batholith region. Resolution of the age and probable magmatic source of the Butte pre-Main Stage porphyry copper-molybdenum system and of the silver-rich polymetallic quartz vein systems in the northern part of the Boulder batholith documents that these deposits formed from two discrete periods of hydrothermal mineralization related to two discrete magmatic events.

  14. Mineral resources of the Ragged Top Wilderness study area, Pima County, Arizona

    SciTech Connect

    Nowlan, G.A.; Peterson, J.A.; Pitkin, Hanna, W.F. ); Kreidler, T.J. )

    1989-01-01

    This paper reports on the Ragged Top Wilderness Study Area in Arizona which contains Proterozoic granite and sedimentary rocks, Cretaceous volcanic rocks and granodiorite porphyry, and Tertiary rhyolite. Part of the Silver Bell Caldera is included in this study area. No metallic resources were identified. The southwest corner has a high and a moderate resource potential for gold, silver, lead, vanadium, barite, molybdenum, copper, and zinc in vein deposits. The east side has a low resource potential for these elements. Parts of this study area have a moderate potential for copper, silver, gold, and molybdenum in porphyry copper deposits, a low potential for uranium deposits in sedimentary rocks, and a low potential for thorium, rare-earth elements, quartz, feldspar, and mica in granite.

  15. The Laramide Mesa formation and the Ojo de Agua caldera, southeast of the Cananea copper mining district, Sonora, Mexico

    USGS Publications Warehouse

    Cox, Dennis P.; Miller, Robert J.; Woodbourne, Keith L.

    2006-01-01

    The Mesa Formation extends from Cananea, Mexico, southeast to the Sonora River and is the main host rock of Laramide porphyry copper deposits in the Cananea District and at the Alacran porphyry prospect to the east. The Mesa consists of two members-a lower andesite and an upper dacite. The lowest part of the dacite member is a crystal tuff about 100 m thick. This tuff is the outfall of a caldera centered near the village of Ojo de Agua, dated by 40Ar/39Ar at 65.8 Ma ?0.4. The Ojo de Agua Caldera is about 9 km in diameter and is filled by a light gray biotite dacite tuff with abundant flattened pumice fragments. The volume of the caldera is estimated to be 24 km3.

  16. Geology of Saipan, Mariana Islands; Part 2, Petrology and soils

    USGS Publications Warehouse

    Schmidt, R.G.; Johnson, J.H.; McCracken, R.J.

    1957-01-01

    The rocks that comprise the volcanic formations of Saipan are of two principal types: dacites, which are characteristically glassy, and andesites, which are comparatively crystalline. The dacites consist primarily of silicic glass, oligoclase, and silica minerals (quartz, tridymite, cristobalite, chalcedony, and opal). Minor constituents in these rocks are green hornblende, biotite, magnetite, and hematite. The andesites are composed principally of labradorite, hypersthene, augite, and subcalcrc augite. Minor but also characteristic constituents of the andesites are quartz, tridymite, cristobalite, anorthoclase, and accessory magnetite, ilmenite, rutile, and apatite. Nine varieties of dacite and andesite are recognized on the basis of chemical composition, mineralogy, and texture. These are dacite, dacite vitrophyre, dacite perlite, hornblende-bearing dacite porphyry, augite-hypersthene andesite, quartz-bearing augite-hypersthene andesite, quartz-bearing augite-hypersthene andesite porphyry, augite andesite, and hypersthene andesite.

  17. Petrology, composition, and age of intrusive rocks associated with the Quartz Hill molybdenite deposit, southeastern Alaska.

    USGS Publications Warehouse

    Hudson, T.; Smith, James G.; Elliott, R.L.

    1979-01-01

    A large porphyry molybdenum deposit (Quartz Hill deposit) was recently discovered in the heart of the Coast Range batholithic complex about 70 km E of Ketchikan, SE Alaska. Intrusive rocks associated with the mineral deposit form two composite epizonal to hypabyssal stocks and many dikes in country rocks. All observed metallization and alteration is within the Quartz Hill stock. Molybdenite forms fracture coatings and occurs in veins with quartz. Alteration is widespread and includes development of secondary quartz, pyrite, K-feldspar, biotite, white mica, chlorite, and zeolite. Field relations indicate that the stocks were emplaced after regional uplift and erosion of the Coast Range batholithic complex, and K-Ar data show that intrusion and alteration took place in late Oligocene time, about 27 to 30 Ma ago. Data from the Ketchikan quadrangle indicate that porphyry molybdenum metallization in the Coast Range batholithic complex is associated with regionally extensive but spotty, middle Tertiary or younger, felsic magmatism. -from Authors

  18. Concentrations of Cu, growth, and chlorophyll content of field-cultivated wheat growing in naturally enriched Cu soil

    SciTech Connect

    Cook, C.M.; Vardaka, E.; Lanaras, T.

    1997-02-01

    The Serbo-Macedonian massif of northern Greece is notable for the occurrence of numerous small areas of sulphide mineralisation. Varying degrees of porphyry copper mineralisation, associated with post-Miocene volcanic rocks of rhyolitic composition, can be encountered in agricultural fields which are used mainly for wheat production. Although Cu is a trace element essential to plant nutrition, in excess, it is phytotoxic causing stunted growth, chlorosis and root malformation. Previous studies on wheat growing in these naturally enriched Cu soils have shown that plants have reduced growth, chlorosis and chloroplast ultrastructural changes and a reduced efficiency of the photochemistry of photosystem II (PSII). The objective of this study was to examine the relationship between the Cu concentration of the soil and the plant tissue Cu concentration, growth and chlorophyll content of field-cultivated wheat growing in soils with varying degrees of porphyry copper mineralisation. 15 refs., 2 figs., 1 tab.

  19. Mineral exploration potential of ERTS-1 data

    NASA Technical Reports Server (NTRS)

    Brewer, W. A. (Principal Investigator); Erskine, M. C., Jr.; Prindle, R. O.

    1973-01-01

    The author has identified the following significant results. Further analysis of ERTS-1 MSS imagery of Arizona has led to division of the earlier reported three major regional fault/fracture systems into eight subdivisions. These are: System A - N40E to N50E; System B - N50W; System C - N35W; System D - N65E to N75E; System E - N-E; System F - N25W average; System G - N75W average; and System H - close to E-W. Their individual significance to known porphyry coppers and correlation to the Wasatch-Jerome and Front Orogens, the Texas Zone and Basin Range topography is postulated in the report. In this study area of Arizona the ERTS-1 mapped structural trends confirm and greatly extend some concepts of porphyry copper distribution based on prior geologic knowledge of major structural trends.

  20. Support vector machine for multi-classification of mineral prospectivity areas

    NASA Astrophysics Data System (ADS)

    Abedi, Maysam; Norouzi, Gholam-Hossain; Bahroudi, Abbas

    2012-09-01

    In this paper on mineral prospectivity mapping, a supervised classification method called Support Vector Machine (SVM) is used to explore porphyry-Cu deposits. Different data layers of geological, geophysical and geochemical themes are integrated to evaluate the Now Chun porphyry-Cu deposit, located in the Kerman province of Iran, and to prepare a prospectivity map for mineral exploration. The SVM method, a data-driven approach to pattern recognition, had a correct-classification rate of 52.38% for twenty-one boreholes divided into five classes. The results of the study indicated the capability of SVM as a supervised learning algorithm tool for the predictive mapping of mineral prospects. Multi-classification of the prospect for detailed study could increase the resolution of the prospectivity map and decrease the drilling risk.

  1. Life History of Thalerosphyrus (Ephemeroptera: Heptageniidae) in Tropical Rivers with Reference to the Varying Altitude.

    PubMed

    Hamid, Suhaila Ab; Rawi, Che Salmah Md; Ahmad, Abu Hassan

    2016-02-01

    The life history and the influence of environmental parameters on Thalerosphyrus were investigated in two first-order rivers-the Batu Hampar River and the Teroi River of Gunung Jerai, Kedah-in northern peninsular Malaysia. Based on nymphal body length, Thalerosphyrus was found to be trivoltine in both rivers, regardless of the altitudinal difference, but its population abundance was four times higher in the Teroi River, presumably related to its better survival in the lower water temperature. At least nine instars of Thalerosphyrus were detected in the field-collected nymphs. Its life cycle was completed within 2.5-3.0 months, with overlapping cohorts and continual emergence of up to 3 months. The main driving factors of the high abundance of Thalerosphyrus were the water temperature and habitat quality.

  2. Life History of Thalerosphyrus (Ephemeroptera: Heptageniidae) in Tropical Rivers with Reference to the Varying Altitude

    PubMed Central

    Hamid, Suhaila Ab.; Rawi, Che Salmah Md; Ahmad, Abu Hassan

    2016-01-01

    The life history and the influence of environmental parameters on Thalerosphyrus were investigated in two first-order rivers—the Batu Hampar River and the Teroi River of Gunung Jerai, Kedah—in northern peninsular Malaysia. Based on nymphal body length, Thalerosphyrus was found to be trivoltine in both rivers, regardless of the altitudinal difference, but its population abundance was four times higher in the Teroi River, presumably related to its better survival in the lower water temperature. At least nine instars of Thalerosphyrus were detected in the field-collected nymphs. Its life cycle was completed within 2.5–3.0 months, with overlapping cohorts and continual emergence of up to 3 months. The main driving factors of the high abundance of Thalerosphyrus were the water temperature and habitat quality. PMID:27019681

  3. Production of haploids from anther culture of banana [Musa balbisiana (BB)].

    PubMed

    Assani, A; Bakry, F; Kerbellec, F; Haïcour, R; Wenzel, G; Foroughi-Wehr, B

    2003-02-01

    We report here, for the first time, the production of haploid plants of banana Musa balbisiana (BB). Callus was induced from anthers in which the majority of the microspores were at the uninucleate stage. The frequency of callus induction was 77%. Callus proliferation usually preceded embryo formation. About 8% of the anthers developed androgenic embryos. Of the 147 plantlets obtained, 41 were haploids (n=x=11). The frequency of haploid production depended on genotypes used: 18 haploid plants were produced from genotype Pisang klutuk, 12 from Pisang batu, seven from Pisang klutuk wulung and four from Tani. The frequency of regeneration was 1.1%, which was based on the total number of anthers cultured. Diploid plants (2n=2x=22) were also observed in the regenerated plants. The haploid banana plants that were developed will be important material for the improvement of banana through breeding programmes.

  4. Seismology: earthquake risk on the Sunda trench.

    PubMed

    Nalbant, Suleyman S; Steacy, Sandy; Sieh, Kerry; Natawidjaja, Danny; McCloskey, John

    2005-06-09

    On 28 March 2005 the Sunda megathrust in Indonesia ruptured again, producing another great earthquake three months after the previous one. The rupture was contiguous with that of the December 2004 Sumatra-Andaman earthquake, and is likely to have been sparked by local stress, although the triggering stresses at its hypocentre were very small - of the order of just 0.1 bar. Calculations show that stresses imposed by the second rupture have brought closer to failure the megathrust immediately to the south, under the Batu and Mentawai islands, and have expanded the area of increased stress on the Sumatra fault. Palaeoseismologic studies show that the Mentawai segment of the Sunda megathrust is well advanced in its seismic cycle and is therefore a good candidate for triggered failure.

  5. Field survey of the March 28, 2005 Nias-Simeulue earthquake and Tsunami

    USGS Publications Warehouse

    Borrero, J.C.; McAdoo, B.; Jaffe, B.; Dengler, L.; Gelfenbaum, G.; Higman, B.; Hidayat, R.; Moore, A.; Kongko, W.; ,; Peters, R.; Prasetya, G.; Titov, V.; Yulianto, E.

    2011-01-01

    On the evening of March 28, 2005 at 11:09 p.m. local time (16:09 UTC), a large earthquake occurred offshore of West Sumatra, Indonesia. With a moment magnitude (Mw) of 8.6, the event caused substantial shaking damage and land level changes between Simeulue Island in the north and the Batu Islands in the south. The earthquake also generated a tsunami, which was observed throughout the source region as well as on distant tide gauges. While the tsunami was not as extreme as the tsunami of December 26th, 2004, it did cause significant flooding and damage at some locations. The spatial and temporal proximity of the two events led to a unique set of observational data from the earthquake and tsunami as well as insights relevant to tsunami hazard planning and education efforts. ?? 2010 Springer Basel AG.

  6. Tests of Rock Cores Scott Study Area, Missouri

    DTIC Science & Technology

    1970-05-01

    4.5) represent this rock; they are described below. The bulk composition is quartz, plagioclase (near oligoclase), and potash feldspar , with minor...little potassium feldspar is present in these cores. The bulk composition of this rock is quartz, plagio- clase feldspar (near oligoclase), chlorite...biotite, and magnetite (Table 4.6). The phenocrysts are plagioclase feldspar and quartz; by composition, the rock is classified as dacite porphyry in the

  7. Statistical Analysis of Geotechnical Data.

    DTIC Science & Technology

    1987-09-01

    The Data of Fig. 2a. 36 Figure 4. Probability Paper Plot of Compaction Data. 37 Figure 5. Scatter Plot of Compaction Control Data Showing Water 38...Autocorrelation Function of Water Content Over Small Interval 87 of San Francisco Bay Mud. Figure 22. Autocorrelation Function of Water Content Over Large Interval...A Copper 90 Porphyry. Figure 25. Autocorrelation Function of Compacted Water Content in Clay 91 Core of an Embankment Dam. Figure 26. Autocorrelation

  8. Characteristics of Mineralized Volcanic Centers in Javanese Sunda Island Arc, Indonesia

    NASA Astrophysics Data System (ADS)

    Setijadji, L. D.; Imai, A.; Watanabe, K.

    2007-05-01

    The subduction-related arc magmatism in Java island, Sunda Arc, Indonesia might have started in earliest Tertiary period, but the distinctively recognizable volcanic belts related with Java trench subduction occurred since the Oligocene. We compiled geoinformation on volcanic centers of different epochs, distribution of metallic mineral deposits, petrochemistry of volcanic rocks, geologic structures, and regional gravity image in order to elucidate characteristics of the known mineralized volcanic centers. Metallic deposits are present in various styles from porphyry-related, high-sulfidation, and low-sulfidation epithermal systems; all related with subaerial volcanism and subvolcanic plutonism. Only few and small occurrences of volcanigenic massive sulfides deposits suggest that some mineralization also occurred in a submarine environment. Most locations of mineral deposits can be related with location of Tertiary volcanic centers along the volcanic arcs (i.e. volcanoes whose genetic link with subduction is clear). On the other side there is no mineralization has been identified to occur associated with backarc magmatism whose genetic link with subduction is under debate. There is strong evidence that major metallic deposit districts are located within compressive tectonic regime and bound by coupling major, deep, and old crustal structures (strike-slip faults) that are recognizable from regional gravity anomaly map. So far the most economical deposits and the only existing mines at major industry scale are high-grade epithermal gold deposits which are young (Upper Miocene to Upper Pliocene), concentrated in Bayah dome complex in west Java, and are associated with alkalic magmatism-volcanism. On the other hand, known porphyry Cu-Au deposits are associated with old (Oligocene to Upper Miocene) stocks, and except for one case, all deposits are located in east Java. Petrochemical data suggest a genetic relationship between porphyry mineralization with low- to

  9. Mineral Resource Team 2010 Activities Summary

    DTIC Science & Technology

    2011-01-29

    sills of granite porphyry and aplite. Thus, the volcanic rocks comprise the roof of a very large intrusive igneous complex. Moreover, the volcanic...Deposit: Copper ores associated with intrusive igneous rocks , and the fluids that accompany them, during magmatic emplacement and crystallization...quartzite, paragneiss, and small intrusive igneous rocks . Findings from the USGS field report on those locations are summarized below, with additional

  10. Geologic map of the Mount Sherman 7.5' quadrangle, Lake and Park Counties, Colorado

    USGS Publications Warehouse

    Bohannon, Robert G.; Ruleman, Chester A.

    2013-01-01

    The Mount Sherman 7.5- minute quadrangle is located along the crest of the Mosquito Range in between Leadville and Fairplay, Colorado. There are eleven 13,000-foot peaks and one fourteener, Mount Sherman, within the quadrangle. General elevations range from 10,400–14,036 feet (3,200–4,278 meters). The western half of the quadrangle primarily consists of Proterozoic granitic rocks reverse faulted over Paleozoic sedimentary rocks during the Laramide orogeny of late Cretaceous and Paleocene time. Coeval to this contractional event, sills and laccoliths of the White porphyry group (which probably includes rocks equivalent to the Pando Porphyry) were emplaced in the surrounding country rocks. Igneous activity continued into the Late Eocene with the emplacement of the Sacramento Porphyry (about 43.9 Ma) and the Gray porphyry group (about 36.7 Ma), and as young as 29 Ma to the north within the Climax quadrangle. With the inception of the Rio Grande rift within the region, the Paleozoic sedimentary rocks and Late Cretaceous to early Oligocene igneous rocks were extensionally faulted and tilted to the east. This resulted in the present 20–30 degree dip-slope of these rocks on top of Proterozoic basement rocks within the eastern half of the quadrangle. This extensional regime has continued well into the Pliocene. Within the southwestern quadrant, suspicious lineaments, alignment of springs, and continuous, measureable escarpments provide reasonable evidence for Quaternary tectonic activity along the western flank of the range. Pleistocene glaciers have dramatically sculpted the region, providing exceptional exposure of the region’s bedrock and structure.

  11. The uranium-bearing nickel-cobalt-native silver deposits in the Black Hawk district, Grant County, New Mexico

    USGS Publications Warehouse

    Gillerman, Elliot; Whitebread, Donald H.

    1953-01-01

    The Black Hawk (Bullard Peak) district, Grant County, N. Mex., is 21 miles by road west of Silver City. From 1881 to 1893 more than $1,000,000.00 of high-grade silver ore is reported to have been shipped from the district. Since 1893 there has been no mining in the district except during a short period in 1917 when the Black Hawk mine was rehabilitated. Pre-Cambrian quartz diorite gneiss, which contains inclusions of quartzite, schist, monzonite, and quartz monzonite, is the most widespread rock in the district. The quartz diorite gneiss is intruded by many pre-Cambrian and younger rocks, including diorite granite, diabase, monzonite porphyry and andesite and is overlain by the Upper Cretaceous Beartooth quartzite. The monzonite porphyry, probably of late Cretaceous or early Tertiary age, forms a small stock along the northwestern edge of the district and numerous dikes and irregular masses throughout the district. The ore deposits are in fissure veins that contain silver, cobalt, and uranium. The ore minerals, which include native silver, niccolite, millerite, skutterudite, nickel skutterudite, bismuthinite, pitchblende, and sphalerite, are in a carbonate gangue in narrow, persistent veins, most of which trend northeasterly. Pitchblende has been identified in the Black Hawk and the Alhabra deposits and unidentified radioactive minerals were found at five other localities. The deposits that contain the radioactive minerals constitude a belt 600 to 1,500 feet wide that trends about N. 45° E., and is approximately parallel to the southeastern boundary of the monzonite porphyry stock. All the major ore deposits are in the quartz diorite gneiss in close proximity to the monzonite porphyry. The ore deposits are similar to the deposits at Great Bear Lake, Canada, and Joachimstahl, Czechoslovakia.

  12. Mining Operations.

    DTIC Science & Technology

    1984-09-12

    Austro-Hungarian; (14) Swiss; (15) Gangeud; (16) syenite in general; (17) granite, diorite, syenite ; (18) hard granite; (19) Voronezh; (20) Serdobol’sk...the formula 46g= CM.c where c - drilling speed in 1 minute. Rocks c f Quartzite, very hard syenite 2.2 21 Adesinophyr, hard greywacke 3.4 14...quartzite, very hard syenite ; (33) conglomerate; (34) Bogoslovsk porphyrite; (35) Shokshino quartzite; (36) quartzite, quartz porphyry basalt; (37

  13. Magma emplacement mechanisms and syn-magmatic deformation - a new approach to the Knaben area in Vest Agder, Norway

    NASA Astrophysics Data System (ADS)

    Stormoen, Martin Austin; Slagstad, Trond; Henderson, Iain

    2014-05-01

    The Knaben area, known for its molybdenite mining, defines a N-S striking (~30 degrees dip towards the east) belt, consisting of porphyry granite with a varying density of amphibolite and varieties of deformed granite, lying within the Sirdal Magmatic Belt, is important for understanding the emplacement- and deformation mechanisms of the batholith. Detailed geological mapping combined with geochronology, geochemistry, and structural geology will be the focus areas. Last autumn's fieldwork indicated that several of the formerly mapped enclaves of amphibolite and deformed granite are more coherent then previously indicated, and some have been followed for a few kilometres. Several varieties of granite make up the area, mainly a dominating red porphyry granite, and a grey molybdenite-bearing finer grained granite. Structural investigations revealed consistent "top to the west" compressional kinematics on mappable shear zone networks often displaying west-directed duplex geometries. The Knaben area could possibly comprise a boundary between two individual plutons in the Sirdal Magmatic Belt, or a zone with remaining host rock. Geochronology of the eastern and western plutons will be done. Currently, largely different paleomagnetic vectors of the eastern and western porphyry granites indicate that they are separate plutons. Exploring how the emplacement- and deformation mechanisms have acted and are related, will be one of the main objectives. If the deformed granite is host rock, or syn- to post-magmatic deformed porphyry granite has been one of the major questions. A better understanding of the formation of the Knaben area, also regarding the emplacement of molybdenite, will prove useful for understanding the regional batholith, and possibly the possibility for molybdenite to occur elsewhere. The Sirdal Magmatic Belt, and also Knaben, seem to be of great value for studying magmatic processes.

  14. A deposit model for Mississippi Valley-Type lead-zinc ores: Chapter A in Mineral deposit models for resource assessment

    USGS Publications Warehouse

    Leach, David L.; Taylor, Ryan D.; Fey, David L.; Diehl, Sharon F.; Saltus, Richard W.

    2010-01-01

    This report also describes the geoenvironmental characteristic of MVT deposits. The response of MVT ores in the supergene environment is buffered by their placement in carbonate host rocks which commonly results in near-neutral associated drainage water. The geoenvironmental features and anthropogenic mining effects presented in this report illustrates this important environmental aspect of MVT deposits which separates them from other deposit types (especially coal, VHMS, Cu-porphyry, SEDEX, acid-sulfate polymetallic vein).

  15. Contrasting hydrological processes of meteoric water incursion during magmatic-hydrothermal ore deposition: An oxygen isotope study by ion microprobe

    NASA Astrophysics Data System (ADS)

    Fekete, Szandra; Weis, Philipp; Driesner, Thomas; Bouvier, Anne-Sophie; Baumgartner, Lukas; Heinrich, Christoph A.

    2016-10-01

    Meteoric water convection has long been recognized as an efficient means to cool magmatic intrusions in the Earth's upper crust. This interplay between magmatic and hydrothermal activity thus exerts a primary control on the structure and evolution of volcanic, geothermal and ore-forming systems. Incursion of meteoric water into magmatic-hydrothermal systems has been linked to tin ore deposition in granitic plutons. In contrast, evidence from porphyry copper ore deposits suggests that crystallizing subvolcanic magma bodies are only affected by meteoric water incursion in peripheral zones and during late post-ore stages. We apply high-resolution secondary ion mass spectrometry (SIMS) to analyze oxygen isotope ratios of individual growth zones in vein quartz crystals, imaged by cathodo-luminescence microscopy (SEM-CL). Existing microthermometric information from fluid inclusions enables calculation of the oxygen isotope composition of the fluid from which the quartz precipitated, constraining the relative timing of meteoric water input into these two different settings. Our results confirm that incursion of meteoric water directly contributes to cooling of shallow granitic plutons and plays a key role in concurrent tin mineralization. By contrast, data from two porphyry copper deposits suggest that downward circulating meteoric water is counteracted by up-flowing hot magmatic fluids. Our data show that porphyry copper ore deposition occurs close to a magmatic-meteoric water interface, rather than in a purely magmatic fluid plume, confirming recent hydrological modeling. On a larger scale, the expulsion of magmatic fluids against the meteoric water interface can shield plutons from rapid convective cooling, which may aid the build-up of large magma chambers required for porphyry copper ore formation.

  16. The Ajo Mining District, Pima County, Arizona--Evidence for Middle Cenozoic Detachment Faulting, Plutonism, Volcanism, and Hydrothermal Alteration

    USGS Publications Warehouse

    Cox, Dennis P.; Force, Eric R.; Wilkinson, William H.; More, Syver W.; Rivera, John S.; Wooden, Joseph L.

    2006-01-01

    Introduction: The Ajo porphyry copper deposit and surrounding Upper Cretaceous rocks have been separated from their plutonic source and rotated by detachment faulting. Overlying middle Cenozoic sedimentary and volcanic rocks have been tilted and show evidence for two periods of rotation. Following these rotations, a granitic stock (23.7?0.2 Ma) intruded basement rocks west of the Ajo deposit. This stock was uplifted 2.5 km to expose deep-seated Na-Ca alteration.

  17. Geology and mineral resources of the Port Moller region, western Alaska Peninsula, Aleutian arc: A section in USGS research on mineral resources - 1989: Program and abstracts

    USGS Publications Warehouse

    Wilson, Frederic H.; White, Willis H.; Detterman, Robert L.

    1988-01-01

    Geologic mapping of the Port Moller, Stepovak Bay, and Simeonof Island quadrangles was begun under the auspices of the Alaska Mineral Resource Assessment Program (AMRAP) in 1983 . Two important mineral deposits are located in the Port Moller quadrangle; the Pyramid prospect is the largest copper porphyry system in the Aleutian Arc, and the Apollo Mine is the only gold mine to reach production status in the Aleutian Arc.

  18. Seasonal trends in abundance and composition of marine debris in selected public beaches in Peninsular Malaysia

    NASA Astrophysics Data System (ADS)

    Mobilik, Julyus-Melvin; Ling, Teck-Yee; Husain, Mohd-Lokman Bin; Hassan, Ruhana

    2015-09-01

    The abundance and composition of marine debris were investigated at Saujana (in the state of Negeri Sembilan) and Batu Rakit (in the state of Terengganu) beaches during surveys conducted in December 2012 (northeast monsoon), May 2013 (intermediate monsoon) and July 2013 (southwest monsoon). A total of 4,682 items of debris weighing 231.4 kg were collected and sorted. Batu Rakit received substantially greater quantities of debris (815±717 items/km or 40.4±13.0 kg/km) compared to Saujana (745±444 items/km or 36.7±18.0 kg/km). Total debris item was more abundant during the southwest monsoon (SWM) (1,122±737 items/km) compared to the northeast monsoon (NEM) (825±593 items/ km) and the intermediate monsoon (IM) (394±4 items/km) seasons. Plastic category (88%) was the most numerous items collected and object items contributed 44.18% includes packaging, plastic fragments, cups, plastic shopping bags, plastic food wrapper, clear plastic bottles from the total debris items collected. Object items associated with common source (47%) were the highest debris accumulated, followed by terrestrial (30%) and marine (23%) sources. The high percentage of common and terrestrial sources during SWM season requires immediate action by marine environment stakeholders to develop and introduce strategies to reduce if not totally eliminates the marine debris in the marine environment. Awareness should be continued and focused on beach users and vessels' crew to alert them on the alarming accumulation rate of marine debris and its pathways into the marine environment.

  19. The importance of protected areas for the forest and endemic avifauna of Sulawesi (Indonesia).

    PubMed

    Lee, Tien Ming; Sodhi, Navjot S; Prawiradilaga, Dewi M

    2007-09-01

    Protected areas are critical for the conservation of residual tropical forest biodiversity, yet many of these are being deforested by humans both within and outside of their administrative boundaries. Therefore, it is critical to document the significance of protected areas for conserving tropical biodiversity, particularly in mega-diverse Southeast Asia. We evaluated the importance of protected areas (national parks [NP], nature reserves [NR], and wildlife reserves [WR]) in preserving avifaunal diversity, particularly the endemic and forest species, on the island of Sulawesi. This island has one of the highest numbers of endemic avifauna genera (12) globally and is also experiencing heavy deforestation. Rarefaction analyses and species estimators showed that parks and reserves consistently recorded higher number of forest, endemic, and endemic forest bird species, in addition to larger population densities, than in their surrounding human-modified areas across eight protected areas (Gunung Manembo-nembo WR, Tangkoko-Batu Angus and Dua Saudara NR, Gunung Ambang NR, Bogani Nani Wartabone NP, Gunung Tinombala NR, Gunung Sojol NR, Lore Lindu NP, and Rawa Aopa Watumohai NP). This implies that protecting natural forests must remain as one of the fundamental conservation strategies in Sulawesi. Two small reserves (Gunung Manembo-nembo WR and Tangkoko-Batu Angus and Dua Saudara NR), however, had high number of forest and endemic bird species both within and outside their boundaries, suggesting the importance of buffer areas for augmenting small reserves so as to improve their conservation value. Ordination analyses revealed the differential response of bird species to different environmental factors (e.g., native tree cover), highlighting the significance of forested habitats with dense native vegetation cover for effective conservation of forest dependent and endemic avifauna. In addition, the distinctiveness in bird species composition among protected areas highlights

  20. A Study of Flood Evacuation Center Using GIS and Remote Sensing Technique

    NASA Astrophysics Data System (ADS)

    Mustaffa, A. A.; Rosli, M. F.; Abustan, M. S.; Adib, R.; Rosli, M. I.; Masiri, K.; Saifullizan, B.

    2016-07-01

    This research demonstrated the use of Remote Sensing technique and GIS to determine the suitability of an evacuation center. This study was conducted in Batu Pahat areas that always hit by a series of flood. The data of Digital Elevation Model (DEM) was obtained by ASTER database that has been used to delineate extract contour line and elevation. Landsat 8 image was used for classification purposes such as land use map. Remote Sensing incorporate with GIS techniques was used to determined the suitability location of the evacuation center from contour map of flood affected areas in Batu Pahat. GIS will calculate the elevation of the area and information about the country of the area, the road access and percentage of the affected area. The flood affected area map may provide the suitability of the flood evacuation center during the several levels of flood. The suitability of evacuation centers can be determined based on several criteria and the existing data of the evacuation center will be analysed. From the analysis among 16 evacuation center listed, there are only 8 evacuation center suitable for the usage during emergency situation. The suitability analysis was based on the location and the road access of the evacuation center toward the flood affected area. There are 10 new locations with suitable criteria of evacuation center proposed on the study area to facilitate the process of rescue and evacuating flood victims to much safer and suitable locations. The results of this study will help in decision making processes and indirectly will help organization such as fire-fighter and the Department of Social Welfare in their work. Thus, this study can contribute more towards the society.

  1. Mining resettlement and rural development in Malaysia.

    PubMed

    Khalid, H N

    1992-07-01

    The Malaysian government has employed 3 kinds of resettlement schemes: 1) resettlement of farmers under modern agricultural and land development programs to grow cash crops; 2) resettlement of rural population in well-guarded locations to isolate them from communist insurgents; and 3) resettlement and compensation of population displaced thorough resource exploitation such as construction of dams and mining. The Kinta Valley resettlement is examined in the example of 3 villages where tin mining encroached on their agricultural land. 98 households were included in the sample from Batu Bertudung, Tekka, and Jelutung that had been settled in the 1940s. The villagers were eventually evacuated and sustained technological, pecuniary, and psychological losses. The economic loses involved property, land, and crops, and social losses comprised social networks, neighborhood, and stability. 81.7% of the villagers who were left landless successfully insisted on complete relocation of their villagers in new villages in claims to the respective tin mining companies through their newly formed village action committees in the mid-1960s. The compensation consisted of 1) group compensation by planned resettlement, 2) cash payment, and 3) replacement of the former plot with another piece of land. Social needs were not included in the calculation and the compensation received reflected roughly their economic worth at the time. The villagers of Tekka and Jelutung had their houses rebuilt which were comparable to their old homes using new materials and stronger foundations. Those from Batu Bertudung were resettled in another village, and were compensated in cash to rebuild their homes themselves. Basic amenities were insufficient: new wells had to be dug, the public standpipe was overused, and only dirt roads were constructed. The government provided most basic amenities 5-6 years later under the rural development program.

  2. Surface uplift history of the incipient Banda arc-continent collision: Geology and synorogenic foraminifera of Rote and Savu Islands, Indonesia

    NASA Astrophysics Data System (ADS)

    Roosmawati, Nova; Harris, Ron

    2009-12-01

    Field mapping and analysis of foraminifera from synorogenic pelagic units of Rote and Savu Islands, Indonesia reveals high rates of surface uplift of the incipient Banda arc-continent collision during the past 1.8 myr. New geological maps of these islands document accretion to the Banda forearc of Triassic through Tertiary sedimentary cover units from the down-going Australian continental margin. Foraminifera-rich synorogenic deposits of the Batu Putih Formation unconformably overlie these accreted units. We use paleodepth versus time estimates from benthic and planktic foraminifera's to measure long-term surface uplift rates for the accretionary wedge. Although strong currents in the region cause some problems with reworking, several distinctive species have been found. Synorogenic deposits in Savu and Rote yield foraminifer's of biozone Neogene (N) 18 to N22 (5.6-1.0 myr) that were deposited at estimated depths of around 3000 m. These deposits are unconfomrably overlain by uplifted coral terraces. The highest coral terraces in Savu are > 300 m above sea level and perhaps as old as 0.8 myr. In Rote the highest coral terrace is 200 above sea level and ~ 0.2 myr old. These data indicate that collision of the Australian continental margin with the Banda Arc, which initiated much earlier in Timor, has propagated westward towards Rote where it is in the initial stages of accretionary wedge emergence. Collision of the Scott Plateau propagated SE from Sumba (2-3 Ma) to Savu (1.0-0.5 Ma) and then to Rote (0.2 Ma). Average rates of surface uplift of the Batu Putih Formation pelagic deposits during the past 2 myr in Rote and Savu are ~ 1.5 and 2.3 mm/a, respectively. The rise of these islands is clogging the Indo-Pacific seaway.

  3. Flood Water Level Mapping and Prediction Due to Dam Failures

    NASA Astrophysics Data System (ADS)

    Musa, S.; Adnan, M. S.; Ahmad, N. A.; Ayob, S.

    2016-07-01

    Sembrong dam has undergone overflow failure. Flooding has been reported to hit the town, covering an area of up to Parit Raja, located in the district of Batu Pahat. This study aims to identify the areas that will be affected by flood in the event of a dam failure in Sembrong Dam, Kluang, Johor at a maximum level. To grasp the extent, the flood inundation maps have been generated by using the InfoWorks ICM and GIS software. By using these maps, information such as the depth and extent of floods can be identified the main ares flooded. The flood map was created starting with the collection of relevant data such as measuring the depth of the river and a maximum flow rate for Sembrong Dam. The data were obtained from the Drainage and Irrigation Department Malaysia and the Department of Survey and Mapping and HLA Associates Sdn. Bhd. Then, the data were analyzed according to the established Info Works ICM method. The results found that the flooded area were listed at Sri Lalang, Parit Sagil, Parit Sonto, Sri Paya, Parit Raja, Parit Sempadan, Talang Bunut, Asam Bubok, Tanjung Sembrong, Sungai Rambut and Parit Haji Talib. Flood depth obtained for the related area started from 0.5 m up to 1.2 m. As a conclusion, the flood emanating from this study include the area around the town of Ayer Hitam up to Parit Raja approximately of more than 20 km distance. This may give bad implication to residents around these areas. In future studies, other rivers such as Sungai Batu Pahat should be considered for this study to predict and reduce the yearly flood victims for this area.

  4. [Spectral characteristics and implication of granite from pozaiying molybdenite deposits in west of Guangdong].

    PubMed

    An, Yan-Fei; Zhong, Li-li; Zhou, Yang-Zhang; Chen, Qing; Li, Xing-yuan

    2014-06-01

    Some granite samples from Pozaiying molybdenite deposits in the west of Guangdong were retrieved to characterize the spectral signature of XRD, FT-NIR and Raman. The results show that compared to the Porphyry granite and granite in the far zone, the signal of XRD and Raman of granite in near zone is weaker while the signal of FT-NIR is stronger. The authors' analyses indicate that the FWHM of quartz (101) peak in XRD, Sericite peak (4 529 cm(-1)) in FT-NIR and quartz peak in Raman shift from the latter are higher than those of former two. Those spectral characteristics indicate that compared with other samples, the content of petrogenetic mineral in samples from near zone is lower while the content of alteration mineral is higher, and its crystallinity and crystallization temperatures are both lower. The authors' studies suggest that there may be an alteration zone, embracing the granite-porphyry, which comprised low temperature mineral, and the quartz-porphyry which related to molybdenite mineralization belongs to the zone near Guanshanzhang mass.

  5. Apatite trace element and halogen compositions as petrogenetic-metallogenic indicators: Examples from four granite plutons in the Sanjiang region, SW China

    NASA Astrophysics Data System (ADS)

    Pan, Li-Chuan; Hu, Rui-Zhong; Wang, Xin-Song; Bi, Xian-Wu; Zhu, Jing-Jing; Li, Chusi

    2016-06-01

    The abundances of trace elements including Sr, Ga and rare earth elements (REE) and halogens in apatite crystals from four intermediate-felsic plutons in the Zhongdian terrane in the Sanjiang region have been determined using electron microprobe and laser ablation inductively coupled plasma mass spectrometry to evaluate the potential of apatite as a petrogenic-metallogenic indicator. The selected plutons include one that is not mineralized (the Triassic Xiuwacu pluton, or the TXWC pluton), one that hosts a porphyry-type Cu deposit (the Pulang pluton, or the PL pluton), one that hosts a porphyry-type Mo deposit (the Tongchanggou pluton, or the TCG pluton), and one that hosts a vein-type Mo deposit (the Cretaceous Xiuwacu pluton, or the CXWC pluton). Except for the CXWC pluton, the other three plutons have adakite-like trace element signatures in whole rocks. The results from this study show that REE, Sr and halogens in apatite can be used to track magma compositions, oxidation states and crystallization history. Apatite crystals from the adakite-like plutons are characterized by much higher Sr/Y and δEu than the non-adakite-type pluton. This means that apatite, which is not susceptible to alteration, is a useful tool for identifying the adakite-like plutons that no longer preserve the initial Sr/Y ratios in whole rocks due to weathering and hydrothermal alteration. Based on apatite Ga contents and δEu values, it is inferred that the parental magmas for the two adakite-like plutons containing porphyry-type Cu and Mo mineralization are more oxidized than that for the non-adakite-type pluton containing vein-type Mo mineralization. Apatite crystals from the vein-type Mo deposit have much lower Cl/F ratios than those from the porphyry-type Cu and Mo deposits. Apatite crystals from the adakite-like pluton without Cu or Mo mineralization is characterized by much lower Cl/F ratios than those from the adakite-like plutons that host the porphyry-type Cu and Mo deposits. The

  6. Eruption of Deep Mushy Magma from the Searchlight Magma System, Southern Nevada (USA): a Crystal Size Distribution and Geochemical Analysis

    NASA Astrophysics Data System (ADS)

    Bazar, D.; Miller, J.; Miller, C.; Dodge, M.; Hodge, K.; Faulds, J.

    2006-12-01

    The Miocene Searchlight pluton and overlying volcanic rocks are exposed in the Eldorado Mountains of southern Nevada within the Colorado River Extensional Corridor. Steep tilting of the pluton and its cover provides an exceptional opportunity to study the magmatic plumbing system from bottom to top, including possible eruptions of magma from the Searchlight magma system. The pluton is approximately 10 km thick and divided into three compositionally distinct units that solidified in monotonic fashion: a 2 km thick upper fine-grained quartz monzonite (solidification front), a 6 km thick lower, more mafic quartz monzonite (cumulate), and a 2 km thick middle granite (extracted melt) [ref]. In addition, near E-W-striking rhyolite and trachydacite porphyry dikes intrude the upper quartz monzonite unit (but not the lower or middle units), and identical trachydacite porphyries (locally > 45 vol. % crystals) occur as irregular pods and masses in the roof area. The trachydacite porphyries superficially resemble trachydacite lavas in part of the overlying volcanic section. Ion probe zircon ages are identical within error for the upper unit, the lower unit, and the trachydacite dikes and pods (206Pb/238U age for samples of each ranging from 16.6±0.3 Ma to 16.9±0.2 Ma 2σ). Ages for the middle granite unit and rhyolite dikes are consistently younger (15.8-16.0 Ma). Crystal size distribution (CSD) analysis on plagioclase has been undertaken on samples from the upper Searchlight and overlying volcanic rocks in order to establish and corroborate linkages between the volcanic and intrusive units and to better understand the growth and solidification history of the Searchlight magma system. The CSD's for the intermediate porphyry dikes and pods that intrude upper Searchlight pluton are identical to trachydacite lava flows and domes erupted onto Proterozoic gneiss and earlier lava flows that comprise the roof of the pluton. The CSD's for these rocks are distinctly concave up and

  7. Ages and sources of components of Zn-Pb, Cu, precious metal, and platinum group element deposits in the goodsprings district, clark county, Nevada

    USGS Publications Warehouse

    Vikre, P.; Browne, Q.J.; Fleck, R.; Hofstra, A.; Wooden, J.

    2011-01-01

    ore breccias and relatively low S and Pb isotope values (??34S values vary from 0-??4%; 206Pb/204Pb <18.5). Copper ?? precious metal-PGE deposits (Cu, Co, Ag, Au, Pd, and Pt) consist of Cu carbonate minerals (after chalcocite and chalcopyrite) and fine-grained quartz that have replaced breccia clasts and margins of fissures in Paleozoic limestones and dolomites near porphyritic intrusions. Gold ?? silver deposits occur along contacts and within small-volume stocks and dikes of feldspar porphyry, one textural variety of porphyritic intrusions. Lead isotope compositions of copper ?? precious metal-PGE, gold ?? silver, and lead-dominant carbonate replacement deposits are similar to those of Mojave crust plutons, indicating derivation of Pb from 1.7 Ga crystalline basement or from Late Proterozoic siliciclastic sedimentary rocks derived from 1.7 Ga crystalline basement. Four texturally and modally distinctive porphyritic intrusions are exposed largely in the central part of the district: feldspar quartz porphyry, plagioclase quartz porphyry, feldspar biotite quartz porphyry, and feldspar porphyry. Intrusions consist of 64 to 70 percent SiO2 and variable K2O/Na2O (0.14-5.33) that reflect proportions of K-feldspar and albite phenocrysts and megacrysts as well as partial alteration to K-mica; quartz and biotite phenocrysts are present in several subtypes. Albite may have formed during emplacement of magma in brine-saturated basinal strata, whereas hydrothermal alteration of matrix, phenocrystic, and megacrystic feldspar and biotite to K-mica, pyrite, and other hydrothermal minerals occurred during and after intrusion emplacement. Small volumes of garnet-diopside-quartz and retrograde epidote-mica-amphibole skarn have replaced carbonate rocks adjacent to one intrusion subtype (feldspar-quartz porphyry), but alteration of carbonate rocks at intrusion contacts elsewhere is inconsp. Uranium-lead ages of igneous zircons vary inconsistently from ?? 180 to 230

  8. Geochemical constraints on adakites of different origins and copper mineralization

    USGS Publications Warehouse

    Sun, W.-D.; Ling, M.-X.; Chung, S.-L.; Ding, X.; Yang, X.-Y.; Liang, H.-Y.; Fan, W.-M.; Goldfarb, R.; Yin, Q.-Z.

    2012-01-01

    The petrogenesis of adakites holds important clues to the formation of the continental crust and copper ?? gold porphyry mineralization. However, it remains highly debated as to whether adakites form by slab melting, by partial melting of the lower continental crust, or by fractional crystallization of normal arc magmas. Here, we show that to form adakitic signature, partial melting of a subducting oceanic slab would require high pressure at depths of >50 km, whereas partial melting of the lower continental crust would require the presence of plagioclase and thus shallower depths and additional water. These two types of adakites can be discriminated using geochemical indexes. Compiled data show that adakites from circum-Pacific regions, which have close affinity to subduction of young hot oceanic plate, can be clearly discriminated from adakites from the Dabie Mountains and the Tibetan Plateau, which have been attributed to partial melting of continental crust, in Sr/Y-versus-La/Yb diagram. Given that oceanic crust has copper concentrations about two times higher than those in the continental crust, whereas the high oxygen fugacity in the subduction environment promotes the release of copper during partial melting, slab melting provides the most efficient mechanism to concentrate copper and gold; slab melts would be more than two times greater in copper (and also gold) concentrations than lower continental crust melts and normal arc magmas. Thus, identification of slab melt adakites is important for predicting exploration targets for copper- and gold-porphyry ore deposits. This explains the close association of ridge subduction with large porphyry copper deposits because ridge subduction is the most favorable place for slab melting. ?? 2012 by The University of Chicago.

  9. Structural Style and Tectonic Evolution of the Domeyko Range, North Chilean Precordillera

    NASA Astrophysics Data System (ADS)

    Amilibia, A.; Sabat, F.; McClay, K.; Munoz, J.; Roca, E.; Chong, G.

    2007-05-01

    The structure of the Domeyko Precordillera is dominated by a number of elongated N-S trending basement ridges. These ridges were exhumed by steep reverse N-S faults that deformed the Mesozoic-Cenozoic cover. The vergence of the fault system varies along the strike, conferring an apparent doubly-vergent pop-up geometry to the axial zone. New structural data show that these geometries resulted from the reactivation and inversion of both the Triassic and the Late Jurassic - Early Cretaceous extensional faults. Typical basement short-cut faults are present. Basement faults uplifted the Paleozoic rocks of the hanging wall and transferred part of the shortening to the Mesozoic - Cenozoic cover of the footwall. Both thick and thin-skinned fault systems have a common origin and root in a rear basement fault. Fieldwork provided little evidence of strike-slip movement in these N-S basement faults. Tertiary porphyry intrusion emplacement was strongly controlled by basement faults that facilitated ascension of magma and its intrusion into the sedimentary cover as sills in the hanging wall anticlines. The Late Eocene-Early Oligocene giant porphyry copper bodies (Chuquicamata, La Escondida, El Salvador) located in the Domeyko Range show an adakitic affinity. This affinity together with structural evidence indicates that porphyry emplacement occurred at the end of the basement-involved contractional stage and points to the existence of a flat-slab subducting beneath the Central Andes (22°-26° SL). The eastward migrating compressional regime in the upper plate from the Late Cretaceous onward could be attributed to the shallowing of this slab.

  10. New Mexico structural zone - An analogue of the Colorado mineral belt

    USGS Publications Warehouse

    Sims, P.K.; Stein, H.J.; Finn, C.A.

    2002-01-01

    Updated aeromagnetic maps of New Mexico together with current knowledge of the basement geology in the northern part of the state (Sangre de Cristo and Sandia-Manzano Mountains)-where basement rocks were exposed in Precambrian-cored uplifts-indicate that the northeast-trending Proterozoic shear zones that controlled localization of ore deposits in the Colorado mineral belt extend laterally into New Mexico. The shear zones in New Mexico coincide spatially with known epigenetic precious- and base-metal ore deposits; thus, the mineralized belts in the two states share a common inherited basement tectonic setting. Reactivation of the basement structures in Late Cretaceous-Eocene and Mid-Tertiary times provided zones of weakness for emplacement of magmas and conduits for ore-forming solutions. Ore deposits in the Colorado mineral belt are of both Late Cretaceous-Eocene and Mid-Tertiary age; those in New Mexico are predominantly Mid-Tertiary in age, but include Late Cretaceous porphyry-copper deposits in southwestern New Mexico. The mineralized belt in New Mexico, named the New Mexico structural zone, is 250-km wide. The northwest boundary is the Jemez subzone (or the approximately equivalent Globe belt), and the southeastern boundary was approximately marked by the Santa Rita belt. Three groups (subzones) of mineral deposits characterize the structural zone: (1) Mid-Tertiary porphyry molybdenite and alkaline-precious-metal deposits, in the northeast segment of the Jemez zone; (2) Mid-Tertiary epithermal precious-metal deposits in the Tijeras (intermediate) zone; and (3) Late Cretaceous porphyry-copper deposits in the Santa Rita zone. The structural zone was inferred to extend from New Mexico into adjacent Arizona. The structural zone provides favorable sites for exploration, particularly those parts of the Jemez subzone covered by Neogene volcanic and sedimentary rocks. ?? 2002 Published by Elsevier Science B.V.

  11. Visualizing trace element distribution in quartz using cathodoluminescence, electron microprobe, and laser ablation-inductively coupled plasma-mass spectrometry

    USGS Publications Warehouse

    Rusk, Brian; Koenig, Alan; Lowers, Heather

    2011-01-01

    Cathodoluminescent (CL) textures in quartz reveal successive histories of the physical and chemical fluctuations that accompany crystal growth. Such CL textures reflect trace element concentration variations that can be mapped by electron microprobe or laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Trace element maps in hydrothermal quartz from four different ore deposit types (Carlin-type Au, epithermal Ag, porphyry-Cu, and MVT Pb-Zn) reveal correlations among trace elements and between trace element concentrations and CL textures. The distributions of trace elements reflect variations in the physical and chemical conditions of quartz precipitation. These maps show that Al is the most abundant trace element in hydrothermal quartz. In crystals grown at temperatures below 300 °C, Al concentrations may vary by up to two orders of magnitude between adjacent growth zones, with no evidence for diffusion. The monovalent cations Li, Na, and K, where detectable, always correlate with Al, with Li being the most abundant of the three. In most samples, Al is more abundant than the combined total of the monovalent cations; however, in the MVT sample, molar Al/Li ratios are ~0.8. Antimony is present in concentrations up to ~120 ppm in epithermal quartz (~200–300 °C), but is not detectable in MVT, Carlin, or porphyry-Cu quartz. Concentrations of Sb do not correlate consistently with those of other trace elements or with CL textures. Titanium is only abundant enough to be mapped in quartz from porphyry-type ore deposits that precipitate at temperatures above ~400 °C. In such quartz, Ti concentration correlates positively with CL intensity, suggesting a causative relationship. In contrast, in quartz from other deposit types, there is no consistent correlation between concentrations of any trace element and CL intensity fluctuations.

  12. Reconstructing Magmatic-Hydrothermal Systems via Geologic Mapping of the Tilted, Cross-sectional Exposures of the Yerington District, Nevada

    NASA Astrophysics Data System (ADS)

    Dilles, J. H.; Proffett, J. M.

    2011-12-01

    The Jurassic Yerington batholith was cut by Miocene to recent normal faults and tilted ~90° west (Proffett, 1977). Exposures range from the volcanic environment to ~6 km depth in the batholith. Magmatic-hydrothermal fluids derived from the Luhr Hill granite and associated porphyry dikes produced characteristic porphyry copper mineralization and rock alteration (K-silicate, sericitic, and advanced argillic) in near-vertical columnar zones above cupolas on the deep granite. In addition, saline brines derived from the early Mesozoic volcanic and sedimentary section intruded by the batholith were heated and circulated through the batholith producing voluminous sodic-calcic and propylitic alteration. The magnetite-copper ore body at Pumpkin Hollow is hosted in early Mesozoic sedimentary rocks in the contact aureole of the batholith, and appears to be an IOCG type deposit produced where the sedimentary brines exited the batholith. Although many advances in understanding of Yerington have been made by lab-based geochronology and geochemistry studies, the first order igneous and hydrothermal features were recognized first in the 1960s and 1970s and are best documented by geological mapping at a variety of scales ranging from 1:500 to 1:24,000. The Anaconda technique of mapping mine benches, trenches, and drill cores was perfected here (Einaudi, 1997), and other techniques were used for surface exposures. The geologic and hydrothermal alteration maps establish that hydrothermal alteration accompanied each of several porphyry dike intrusions, and affected more than 100 km3 of rock. Both zonation in alteration mineralogy and vein orientations allow reconstruction of source areas and >5 km-long flow-paths of hydrothermal fluids through the batholith and contact aureole.

  13. The Luanchuan Mo-W-Pb-Zn-Ag magmatic-hydrothermal system in the East Qinling metallogenic belt, China: Constrains on metallogenesis from C-H-O-S-Pb isotope compositions and Rb-Sr isochron ages

    NASA Astrophysics Data System (ADS)

    Cao, Hua-Wen; Zhang, Shou-Ting; Santosh, M.; Zheng, Luo; Tang, Li; Li, Dong; Zhang, Xu-Huang; Zhang, Yun-Hui

    2015-11-01

    The Luanchuan Mo-W-Pb-Zn-Ag polymetallic ore district is located in the East Qinling metallogenic belt on the southern margin of the North China Craton. Two ore fields (Nannihu and Yuku) are recognized in the district, and three types of deposits are identified from the two ore fields as follows: (1) the 6 proximal porphyry-skarn type Mo-W deposits occurring at the inner contact zone of the granite porphyries, (2) the 3 middle skarn-hydrothermal type Zn deposits, and (3) the 8 distal hydrothermal type Pb-Zn-Ag deposits at the periphery of the porphyry. We present C-H-O isotope compositions of hydrothermal quartz and calcite, S-Pb isotope compositions of sulfide minerals, and sphalerite Rb-Sr isochron ages from the 17 deposits. The geochemical and geochronological data from the two ore fields all show systematic temporal and spatial variation, and primarily lead to the following inferences. (1) The temperatures and salinities of the ore-forming fluids decreased during mineralization. The ore-forming fluids gradually evolved from magmatic water to mixed magmatic-meteoric water. (2) The metallogenic components were primarily derived from igneous rocks, with increasing proportions of the materials from the ore-bearing rocks. (3) The mineralization ages of these deposits are close (147-136 Ma), which correspond to the emplacement of the granite intrusions. (4) The three types of deposits and the ore-related late Mesozoic intrusives constitute a unified magmatic-hydrothermal-mineralization system. Finally, we also suggest exploration strategies for the Luanchuan ore district.

  14. LONE PEAK WILDERNESS STUDY AREA, UTAH.

    USGS Publications Warehouse

    Bromfield, Calvin S.; Patten, Lowell L.

    1984-01-01

    On the basis of a mineral survey, three areas in the Lone Peak Wilderness study area, Utah are classed as having mineral-resource potential. These include the Silver Creek district, near the east boundary of the area, the Alpine district near the southwest boundary, and the White Pine Fork area in the northeast part of the area. The Silver Creek and Alpine districts have probable potential for small deposits of silver, lead, zinc and, in addition, the Silver Creek district has a probable potential for small tungsten deposits. Of more significance, the White Pine Fork area has a probable potential for porphyry-type molybdenum resources.

  15. Transition from adakitic to bimodal magmatism induced by the paleo-Pacific plate subduction and slab rollback beneath SE China: Evidence from petrogenesis and tectonic setting of the dike swarms

    NASA Astrophysics Data System (ADS)

    Xia, Yan; Xu, Xisheng; Liu, Lei

    2016-02-01

    The late Mesozoic magmatic record of SE China is dominated by felsic volcanics and intrusions. However, this magmatism mainly occurred in coastal areas at 110-80 Ma, in contrast to poorly researched dike swarms that were emplaced inland at 165-120 Ma. Here, we focus on Early Cretaceous mafic and felsic dike swarms that provide new insights into the tectono-magmatic evolution of SE China. The swarms were intruded into Neoproterozoic plutons and include granodioritic porphyry, granitic porphyry, and diabase dikes. The granodioritic porphyry (128 ± 2 Ma) dikes are geochemically similar to adakitic rocks, suggesting that inland adakitic magmatism occurred between ca. 175 and ca. 130 Ma. The majority of these adakitic rocks are calc-alkaline and have Sr-Nd-Hf-O isotopic compositions that are indicative of derivation from a Neoproterozoic magmatic arc source within the lower crust. The granitic porphyry and diabase dikes were emplaced coevally at ca. 130 Ma, and the former contain high alkali and high field strength element (HFSE; e.g., Zr, Nb, Ce, and Y) concentrations that together with their high Ga/Al and FeOT/(FeOT + MgO) ratios imply an A-type affinity. The widespread ca. 130 Ma magmatism that formed the A-type granites and coeval diabase dikes defines a NE-SW trending inland belt of bimodal magmatism in SE China. The presence of mafic enclaves in some of the A-type granites, and the Sr-Nd-Hf isotopic compositions of the latter are indicative of inadequate mixing between the basement sediment-derived and coeval mantle-derived basaltic melts that define the bimodal magmatism. The transition from adakitic rocks to bimodal magmatism in the inland region of SE China indicates a change in the prevailing tectonic regime. This change was associated with an increase in the dip angle of the northwestward-subducting paleo-Pacific Plate beneath SE China between the Middle Jurassic and the Early Cretaceous. This resulted in a transition from a local intra-plate extensional

  16. COUGAR LAKES-MOUNT AIX WILDERNESS STUDY AREA, WASHINGTON.

    USGS Publications Warehouse

    Simmons, George C.; Van Noy, Ronald M.

    1984-01-01

    A mineral survey of the Cougar Lakes-Mount Aix Wilderness study area in Washington was carried out to assess its mineral-resource potential. The study included reconnaissance geologic mapping and geochemical sampling, statistical analyses of samples, interpretation of an aeromagnetic survey, and an investigation of mining properties. These studies indicate that the area has a probable mineral-resource potential for silver, copper, manganese, mercury, tungsten, and zinc. This resource potential occurs in four small isolated areas in the southern half of the study area, and in a larger area which has a potential for porphyry copper, near the north boundary of the study area.

  17. A general framework of TOPSIS method for integration of airborne geophysics, satellite imagery, geochemical and geological data

    NASA Astrophysics Data System (ADS)

    Abedi, Maysam; Norouzi, Gholam-Hossain

    2016-04-01

    This work presents the promising application of three variants of TOPSIS method (namely the conventional, adjusted and modified versions) as a straightforward knowledge-driven technique in multi criteria decision making processes for data fusion of a broad exploratory geo-dataset in mineral potential/prospectivity mapping. The method is implemented to airborne geophysical data (e.g. potassium radiometry, aeromagnetic and frequency domain electromagnetic data), surface geological layers (fault and host rock zones), extracted alteration layers from remote sensing satellite imagery data, and five evidential attributes from stream sediment geochemical data. The central Iranian volcanic-sedimentary belt in Kerman province at the SE of Iran that is embedded in the Urumieh-Dokhtar Magmatic Assemblage arc (UDMA) is chosen to integrate broad evidential layers in the region of prospect. The studied area has high potential of ore mineral occurrences especially porphyry copper/molybdenum and the generated mineral potential maps aim to outline new prospect zones for further investigation in future. Two evidential layers of the downward continued aeromagnetic data and its analytic signal filter are prepared to be incorporated in fusion process as geophysical plausible footprints of the porphyry type mineralization. The low values of the apparent resistivity layer calculated from the airborne frequency domain electromagnetic data are also used as an electrical criterion in this investigation. Four remote sensing evidential layers of argillic, phyllic, propylitic and hydroxyl alterations were extracted from ASTER images in order to map the altered areas associated with porphyry type deposits, whilst the ETM+ satellite imagery data were used as well to map iron oxide layer. Since potassium alteration is generally the mainstay of porphyry ore mineralization, the airborne potassium radiometry data was used. The geochemical layers of Cu/B/Pb/Zn elements and the first component of PCA

  18. Reconnaissance geochemical survey of the At Taif-Al Bahah region, southern Hijaz, Kingdom of Saudi Arabia

    USGS Publications Warehouse

    Du Bray, E.A.; Doebrich, J.L.

    1982-01-01

    An area south of At Taif containing significant tungsten was confirmed and found to be larger than initially determined. A possible porphyry copper pluton was discovered 50 km south-southeast of At Taif. Thirty kilometers south of At Taif, a low-grade tin anomaly associated with an S-type granite was identified. In addition, the sampling identified seven anomalous areas attributable to rock geochemically atypical of the study region. Finally, although samples from the A1 Lith-Hajrah area collected for an earlier study were found to contain anomalous concentrations of tungsten, samples collected there during this study do not support those findings.

  19. Geologic interpretation of geophysical data for the Wadi al Jarir and Al Jurdhawiyah quadrangles, sheets 25/42 C and D, Kingdom of Saudi Arabia

    USGS Publications Warehouse

    Kleinkopf, M. Dean; Cole, James C.

    1983-01-01

    Correlation of aeromagnetic data and mineral deposit information provide justification for some prospecting guides. Small granodiorite-porphyry plutons with distinct edge anomalies in Murdama metasediments commonly are associated with copper-gold-bearing quartz veins. Vein orientations in these and most other known deposits in the northeastern Shield cannot be sensibly related to the stress field of the Najd fault system, and are believed to predate the Najd or to have been governed by local factors. Small, weakly magnetic targets such as the Bald al Jimalah West tungsten deposit are not indicated by the regional magnetic data.

  20. Are fractal dimensions of the spatial distribution of mineral deposits meaningful?

    USGS Publications Warehouse

    Raines, G.L.

    2008-01-01

    It has been proposed that the spatial distribution of mineral deposits is bifractal. An implication of this property is that the number of deposits in a permissive area is a function of the shape of the area. This is because the fractal density functions of deposits are dependent on the distance from known deposits. A long thin permissive area with most of the deposits in one end, such as the Alaskan porphyry permissive area, has a major portion of the area far from known deposits and consequently a low density of deposits associated with most of the permissive area. On the other hand, a more equi-dimensioned permissive area, such as the Arizona porphyry permissive area, has a more uniform density of deposits. Another implication of the fractal distribution is that the Poisson assumption typically used for estimating deposit numbers is invalid. Based on datasets of mineral deposits classified by type as inputs, the distributions of many different deposit types are found to have characteristically two fractal dimensions over separate non-overlapping spatial scales in the range of 5-1000 km. In particular, one typically observes a local dimension at spatial scales less than 30-60 km, and a regional dimension at larger spatial scales. The deposit type, geologic setting, and sample size influence the fractal dimensions. The consequence of the geologic setting can be diminished by using deposits classified by type. The crossover point between the two fractal domains is proportional to the median size of the deposit type. A plot of the crossover points for porphyry copper deposits from different geologic domains against median deposit sizes defines linear relationships and identifies regions that are significantly underexplored. Plots of the fractal dimension can also be used to define density functions from which the number of undiscovered deposits can be estimated. This density function is only dependent on the distribution of deposits and is independent of the

  1. SHRIMP U-Pb and 40Ar/39Ar age constraints for relating plutonism and mineralization in the Boulder batholith region, Montana

    USGS Publications Warehouse

    Lund, K.; Aleinikoff, J.N.; Kunk, M.J.; Unruh, D.M.; Zeihen, G.D.; Hodges, W.C.; du Bray, E.A.; O'Neill, J. M.

    2002-01-01

    The composite Boulder batholith, Montana, hosts a variety of mineral deposit types, including important silver-rich polymetallic quartz vein districts in the northern part of the batholith and the giant Butte porphyry copper-molybdenum pre-Main Stage system and crosscutting copper-rich Main Stage vein system in the southern part of the batholith. Previous dating studies have identified ambiguous relationships among igneous and mineralizing events. Mineralizing hydrothermal fluids for these types of deposits and magma for quartz porphyry dikes at Butte have all been considered to be late-stage differentiates of the Boulder batholith. However, previous dating studies indicated that the Boulder batholith plutons cooled from about 78 to 72 Ma, whereas copper-rich Main Stage veins at Butte were dated at about 61 Ma. Recent efforts to date the porphyry copper-molybdenum pre-Main Stage deposits at Butte resulted in conflicting estimates of both 64 and 76 Ma for the mineralizing events. Silver-rich polymetallic quartz vein deposits elsewhere in the batholith have not been dated previously. To resolve this controversy, we used the U.S. Geological Survey, Stanford, SHRIMP RG ion mic??roprobe to date single-age domains within zircons from plutonic rock samples and 40Ar/39Ar geochronology to date white mica, biotite, and K-feldspar from mineral deposits. U-Pb zircon ages are Rader Creek Granodiorite, 80.4 ?? 1.2 Ma; Unionville Granodiorite, 78.2 ?? 0.8 Ma; Pulpit Rock granite, 76.5 ?? 0.8 Ma; Butte Granite, 74.5 ?? 0.9 Ma; altered Steward-type quartz porphyry dike (I-15 roadcut), 66.5 ?? 1.0 Ma; altered Steward-type quartz porphyry dike (Continental pit), 65.7 ?? 0.9 Ma; and quartz monzodiorite of Boulder Baldy (Big Belt Mountains), 66.2 ?? 0.9 Ma. Zircons from Rader Creek Granodiorite and quartz porphyry dike samples contain Archean inheritance. The 40Ar/39Ar ages are muscovite, silver-rich polymetallic quartz vein (Basin district), 74.4 ?? 0.3 Ma; muscovite, silver

  2. ABSAROKA PRIMITIVE AREA AND VICINITY, MONTANA.

    USGS Publications Warehouse

    Wedow, Helmuth; Bannister, D'Arcy P.

    1984-01-01

    A mineral-resource appraisal of the Absaroka Primitive Area, Montana indicates a probable resource potential for copper-molybdenum and gold in parts of the area. An area favorable for the occurrence of early Tertiary porphyry-type copper-molybdenum and associated gold deposits lies northwest of Cooke City, along the Cooke City structural sag in the Beartooth uplift. An area favorable for stratabound gold deposits of the Homestake type is in the western part of the area, in and around the Jardine-Crevice Mountain mining district and in lower Hellroaring Creek valley. There is little promise for the occurrence of energy resources in the primitive area.

  3. Complete Analytical Data for Samples of Jurassic Igneous Rocks in the Bald Mountain Mining District, Nevada

    USGS Publications Warehouse

    du Bray, Edward A.

    2009-01-01

    This report presents all petrographic, major oxide, and trace element data for a set of 109 samples collected during an investigation of Jurassic igneous rocks in the Bald Mountain mining district, Nevada. Igneous rocks in the district include the Bald Mountain stock, quartz-feldspar porphyry dikes, basaltic andesite dikes, aplite sills, and rare lamprophyre dikes. These rocks, although variably altered near intrusion-related mineral deposits, are fresh in many parts of the district. Igneous rocks in the district are hosted by Paleozoic sedimentary rocks.

  4. Regional geochemical studies in the Patagonia Mountains, Santa Cruz County, Arizona

    USGS Publications Warehouse

    Chaffee, M.A.; Hill, R.H.; Sutley, S.J.; Watterson, J.R.

    1981-01-01

    The Patagonia Mountains in southern Arizona contain the deeply buried porphyry copper system at Red Mountain as well as a number of other base- and precious-metal mines and prospects. The range contains complex Basin and Range geology with units ranging in age from Precambrian to Holocene. Rock types present include igneous intrusive and extrusive units as well as sedimentary and metamorphic units, most of which have been tectonically disturbed. A total of 264 stream-sediment samples were collected and analyzed for 32 elements. Geochemical maps for Sb, Ag, Pb, Te, B, Mn, Au, Zn, Cu (total), Cu (cold-extractable), and Mo, as well as for Cu (cold-extractable)/Cu (total) and Fe/Mn, are presented. Anomaly patterns for these elements generally occur over the Red Mountain deposit and (or) along a north-northwest trend parallel to the major Harshaw Creek Fault. Much of the entire area sampled contains widespread anomalies for Pb, Te, and Cu; the other elements are only locally anomalous. Various plots of ratios of Cu (cold-extractable) to Cu (total) did not produce any new information not readily apparent on either one of the two copper maps. A plot of ratios of Fe to Mn delineated many areas of pyrite mineralization. Several of these areas may represent the pyritic halos around deeply buried porphyry copper systems. The best ore guide for the Red Mountain porphyry system is the coincidence of positive anomalies of Mo, Pb, and Te and a negative anomaly of Mn. Other areas with anomalies of the same suite of elements are present within the Patagonia Mountains. It is concluded that geochemical sampling, even in a highly contaminated area, can be useful in delineating major geologic features, such as porphyry copper belts and major faults. Multielement geochemical surveys on a regional scale can effectively locate large, deeply buried, zoned mineral systems such as that at Red Mountain. Plots of element ratios, where adequately understood, can provide geochemical information

  5. Typing mineral deposits using their associated rocks, grades and tonnages using a probabilistic neural network

    USGS Publications Warehouse

    Singer, D.A.

    2006-01-01

    A probabilistic neural network is employed to classify 1610 mineral deposits into 18 types using tonnage, average Cu, Mo, Ag, Au, Zn, and Pb grades, and six generalized rock types. The purpose is to examine whether neural networks might serve for integrating geoscience information available in large mineral databases to classify sites by deposit type. Successful classifications of 805 deposits not used in training - 87% with grouped porphyry copper deposits - and the nature of misclassifications demonstrate the power of probabilistic neural networks and the value of quantitative mineral-deposit models. The results also suggest that neural networks can classify deposits as well as experienced economic geologists. ?? International Association for Mathematical Geology 2006.

  6. Osmium isotope constraints on ore metal recycling in subduction zones

    PubMed

    McInnes; McBride; Evans; Lambert; Andrew

    1999-10-15

    Veined peridotite xenoliths from the mantle beneath the giant Ladolam gold deposit on Lihir Island, Papua New Guinea, are 2 to 800 times more enriched in copper, gold, platinum, and palladium than surrounding depleted arc mantle. Gold ores have osmium isotope compositions similar to those of the underlying subduction-modified mantle peridotite source region, indicating that the primary origin of the metals was the mantle. Because the mantle is relatively depleted in gold, copper, and palladium, tectonic processes that enhance the advective transport and concentration of these fluid soluble metals may be a prerequisite for generating porphyry-epithermal copper-gold deposits.

  7. Stratigraphic setting and mineralogy of the Arctic volcanogenic massive sulfide prospect, Ambler district, Alaska.

    USGS Publications Warehouse

    Schmidt, J.M.

    1986-01-01

    The Arctic prospect, south central Brooks Range, is among the 30 largest of 508 volcanic-hosted massive sulphide deposits in the world. The massive sulphide lenses are interlayered with graphitic schist between metamorphosed rhyolite porphyries in Middle Devonian to early Mississippian metamorphosed volcanic, volcaniclastic and sedimentary rocks. Hydrothermal alteration is of three types: chloritic, phyllic s.l., and pyrite-phengite, each type strata-distinctively and respectively below, in, and above the sulphides. Maximum alteration conforms with metal zoning in the sulfides to suggest predominantly northwestward dispersal from a linear vent area in the elongate basin containing the deposit.-G.J.N.

  8. Ultrapotassic dykes in the Moldanubian Zone and their significance for understanding of the post-collisional mantle dynamics during Variscan orogeny in the Bohemian Massif

    NASA Astrophysics Data System (ADS)

    Kubínová, Šárka; Faryad, Shah Wali; Verner, Kryštof; Schmitz, Mark; Holub, František

    2017-02-01

    We report mineral textures, geochemistry and age relations of two ultrapotassic dykes from a dyke swarm in the Western part of the Moldanubian Zone at contact to the Teplá-Barrandian Block. The dykes have orientation almost perpendicular to the NNE-SSW trending Central Bohemian plutonic complex and cross cut metamorphic foliation in basement gneisses and migmatites. Based on mineral compositions and geochemistry, the dykes show close relations to Mg-K syenite plutons in the Moldanubian Zone. The two dykes are vaugnerite and syenite in compositions and contain talc pseudomorphs after olivine within a fine-grained matrix that consists of K-feldspar, phlogopite with small amounts of clinopyroxene and accessory quartz, apatite, titanite and sulphides of Fe, Cu, Ni. The syenite porphyry dyke cross cuts the vaugnerite. It contains quartz phenocrysts and comparing to vaugnerite has lower modal content of talc pseudomorphs. The vaugnerite and syenite porphyry have high K2O (6 to 7 wt.%) and mg-number (0.66-0.74), but low CaO and Na2O contents. The vaugnerite is markedly rich in P2O5 (> 2 wt.%) and comparing to syenite porphyry has higher amount of mantle-incompatible elements (e.g. Rb, Cs, Ba, Pb, Th, U), V and Cr. ID-TIMS analyses on titanite in vaugnerite and on zircon in syenite porphyry yielded 338.59 ± 0.68 and 337.87 ± 0.21 Ma, respectively. Mineral and bulk rock chemistry of the dykes indicates that the source magma was formed by a low degree of partial melting of a highly anomalous domain in the upper mantle which subsequently fractionated and was contaminated with crustal material during its ascent. Formation of ultrapotassic magma is explained by transcurrent shear zones in the mantle lithosphere that occurred due to block rotation and post-collisional mantle dynamics initiated by slab break-off and asthenosphere upwelling into the Moldanubian accretionary complex during the Variscan Orogeny.

  9. MIDDLE MOUNTAIN-TOBACCO ROOT ROADLESS AREA, MONTANA.

    USGS Publications Warehouse

    O'Neill, J. Michael; Cather, Eric E.

    1984-01-01

    A mineral-resource survey of the northern part of the Tobacco Root Mountains, Montana determined that the area included in or enclosed by the Middle Mountain-Tobacco Root Roadless Area contains serveral areas of probable or substantiated mineral-resource potential. Most of the mineralized areas are located in or adjacent to intrusive rocks of Late Cretaceous age. Mineral resources are probably of three types: disseminated and stockwork copper and molybdenum in porphyry-type deposits; gold-silver-quartz veins; and gold-bearing silicified zones. No energy resources were identified in this study.

  10. Self-ordering and complexity in epizonal mineral deposits

    USGS Publications Warehouse

    Henley, Richard W.; Berger, Byron R.

    2000-01-01

    Giant deposits are relatively rare and develop where efficient metal deposition is spatially focused by repetitive brittle failure in active fault arrays. Some brief case histories are provided for epithermal, replacement, and porphyry mineralization. These highlight how rock competency contrasts and feedback between processes, rather than any single component of a hydrothermal system, govern the size of individual deposits. In turn, the recognition of the probabilistic nature of mineralization provides a firmer foundation through which exploration investment and risk management decisions can be made.

  11. Regional Crustal Structures and Their Relationship to the Distribution of Ore Deposits in the Western United States, Based on Magnetic and Gravity Data

    USGS Publications Warehouse

    Hildenbrand, T.G.; Berger, B.; Jachens, R.C.; Ludington, S.

    2000-01-01

    Upgraded gravity and magnetic databases and associated filtered-anomaly maps of western United States define regional crustal fractures or faults that may have guided the emplacement of plutonic rocks and large metallic ore deposits. Fractures, igneous intrusions, and hydrothermal circulation tend to be localized along boundaries of crustal blocks, with geophysical expressions that are enhanced here by wavelength filtering. In particular, we explore the utility of regional gravity and magnetic data to aid in understanding the distribution of large Mesozoic and Cenozoic ore deposits, primarily epithermal and porphyry precious and base metal deposits and sediment-hosted gold deposits in the western United States cordillera. On the broadest scale, most ore deposits lie within areas characterized by low magnetic properties. The Mesozoic Mother Lodge gold belt displays characteristic geophysical signatures (regional gravity high, regional low-to-moderate background magnetic field anomaly, and long curvilinear magnetic highs) that might serve as an exploration guide. Geophysical lineaments characterize the Idaho-Montana porphyry belt and the La Caridad-Mineral Park belt (from northern Mexico to western Arizona) and thus indicate a deep-seated control for these mineral belts. Large metal accumulations represented by the giant Bingham porphyry copper and the Butte polymetallic vein and porphyry copper systems lie at intersections of several geophysical lineaments. At a more local scale, geophysical data define deep-rooted faults and magmatic zones that correspond to patterns of epithermal precious metal deposits in western and northern Nevada. Of particular interest is an interpreted dense crustal block with a shape that resembles the elliptical deposit pattern partly formed by the Carlin trend and the Battle Mountain-Eureka mineral belt. We support previous studies, which on a local scale, conclude that structural elements work together to localize mineral deposits within

  12. New Investigations of the Alleged Meteorite from Igast, Estonia

    NASA Technical Reports Server (NTRS)

    OKeefe, John A.; Lowman, Paul D., Jr.

    1961-01-01

    This paper presents the results of a reinvestigation of the object which allegedly fell at Igast, Estonia, in 1855, and which may be the only example of a meteorite with the chemical composition of a tektite. R is concluded that generally quoted opinions of the artificial nature of this object are based on spurious samples, specifically melted brick and quartz basalt porphyry distributed by a Russian collector. Possibly genuine specimens from this observed fall are in the British Museum, the Paris Museum, and perhaps at the University of Dorpat, Estonia. It is recommended that these specimens be re-examined and that a search for similar objects be made.

  13. Trace elements in hydrothermal quartz: Relationships to cathodoluminescent textures and insights into vein formation

    USGS Publications Warehouse

    Rusk, B.G.; Lowers, H.A.; Reed, M.H.

    2008-01-01

    High-resolution electron microprobe maps show the distribution of Ti, Al, Ca, K, and Fe among quartz growth zones revealed by scanning electron microscope-cathodoluminescence (SEM-CL) from 12 hydrothermal ore deposits formed between ???100 and e1750 ??C. The maps clearly show the relationships between trace elements and CL intensity in quartz. Among all samples, no single trace element consistently correlates with variations in CL intensity. However in vein quartz from five porphyry-Cu (Mo-Au) deposits, CL intensity always correlates positively with Ti concentrations, suggesting that Ti is a CL activator in quartz formed at >400 ??C. Ti concentrations in most rutile-bearing vein quartz from porphyry copper deposits indicate reasonable formation temperatures of 2000 ppm, but in high-temperature quartz, Al concentrations are consistently in the range of several hundred ppm. Aluminum concentrations in quartz refl ect the Al solubility in hydrothermal fluids, which is strongly dependent on pH. Aluminum concentrations in quartz therefore reflect fluctuations in pH that may drive metal-sulfide precipitation in hydrothermal systems. ?? 2008 The Geological Society of America.

  14. Identification of geostructures of continental crust, particularly as they relate to mineral-resource evaluation

    NASA Technical Reports Server (NTRS)

    Gryc, G. (Principal Investigator); Lathram, E. H.

    1972-01-01

    The authors have identified the following significant results. As a precursor to the ERTS-1 investigation, the spatial relationship of geostructures seen on Nimbus IDCS photographs to the distribution of mineralized areas in Alaska and western Canada was analyzed to determine the possible metallogenic significance of the geostructures. In Canada, mercury and porphyry molybdenum deposits are closely associated with strong northwest-trending fault systems; the development of mineralized regions seems related to major crustal zones or fractures trending southwestward across the Cordillera from the Precambrian shield. In Alaska, comparison of the northeast- and northwest-trending set of possible crustal structures shown on the Nimbus photo, with the distribution of known mineral deposits suggests a similar relationship. The mineralized region of massive sulfides in Prince William Sound and upper Copper River areas and of porphyry coppers in the Nabesna area forms a broad northeast-trending belt possibly related to the Minto Arch on the Shield. The belt of metalliferous deposits in the western Alaska Range follows a comparable northeast trend. Mercury deposits, suggested by many to be fault-controlled, together with most tin and tungsten deposits, occupy a northeast-trending belt between the Bristol Bay-Mackenzie Bay linear and extensions of a linear along the lower Yukon River. This belt intersects the northwest-trending Canadian belt of similar deposits in the Fairbanks area.

  15. Low-fluorine Stockwork Molybdenite Deposits

    USGS Publications Warehouse

    Ludington, Steve; Hammarstrom, Jane; Piatak, Nadine M.

    2009-01-01

    Low-fluorine stockwork molybdenite deposits are closely related to porphyry copper deposits, being similar in their tectonic setting (continental volcanic arc) and the petrology (calc-alkaline) of associated igneous rock types. They are mainly restricted to the Cordillera of western Canada and the northwest United States, and their distribution elsewhere in the world may be limited. The deposits consist of stockwork bodies of molybdenite-bearing quartz veinlets that are present in and around the upper parts of intermediate to felsic intrusions. The deposits are relatively low grade (0.05 to 0.2 percent Mo), but relatively large, commonly >50 million tons. The source plutons for these deposits range from granodiorite to granite in composition; the deposits primarily form in continental margin subduction-related magmatic arcs, often concurrent with formation of nearby porphyry copper deposits. Oxidation of pyrite in unmined deposits or in tailings and waste rock during weathering can lead to development of acid-rock drainage and limonite-rich gossans. Waters associated with low-fluorine stockwork molybdenite deposits tend to be nearly neutral in pH; variable in concentrations of molybdenum (10,000 ug/L); below regulatory guidelines for copper, iron, lead, zinc, and mercury; and locally may exceed guidelines for arsenic, cadmium, and selenium.

  16. U-Pb ages of mafic intrusions from the southeast margin of the Wyoming province: Implications for timing of rifting and deformation

    SciTech Connect

    Cox, D.M.; Chamberlain, K.R. . Dept. of Geology and Geophysics); Heaman, L.M. . Dept. of Geology); Snyder, G.L. . Federal Center)

    1993-04-01

    The southeast margin of the Wyoming Province exposed in the Laramie Mountains is dominated by Archean granitic gneiss that has been intruded by mafic dike swarms. The metamorphic grade of these mafic bodies ranges from lower amphibolite to garnet amphibolite facies. Three distinct compositional groups are recognized: (1) plagioclase porphyry; (2) diabase; and (3) peridotite. The diabase intrudes the plagioclase porphyry and locally contains relict igneous textures. The peridotite intrudes both and contain relict olivine and orthopyroxene. Both the granitic gneiss and the mafic intrusions have been deformed into map scale folds with a northwest trending axis, and subsequently refolded about a northeast trending axis. The northeast structures are subparallel to the trend of the Cheyenne belt. In one locality, diabase dikes intrude a 2.05 Ga. granodiorite (K.R. Ludwig in Snyder, et al. 1992). Field relations provide relative ages, and samples were collected of each dike type to determine absolute age by U-Pb geochronological analysis. Preliminary baddeleyite U-Pb data from a folded diabase yields a minimum crystallization age of 2.05 Ga. The mafic intrusions may be related to rifting of the Archean margin, which has been constrained from other ranges in southeast Wyoming to 2.0--2.3 Ga. In addition, the baddeleyite age establishes that much of the deformation of the Archean craton postdates 2.05 Ga. and may be related to suturing along the Cheyenne belt ca. 1.75 Ga.

  17. Near-surface ambient noise tomography in the Baogutu copper deposit area

    NASA Astrophysics Data System (ADS)

    Li, Xin-xin; Li, Qing-chun

    2016-12-01

    The Baogutu copper deposit region is located in the northwestern margin of the Junggar basin, controlled by the NE-SW trend Darbut fault. This region developed mid-late Hercynian (330-320 Ma) intermediate-acid small porphyry bodies. Hosted in the lower carboniferous volcano-sedimentary sequences, the Baogutu porphyry copper deposit has experienced two epochs of fluid metallogenesis after the adakitic magma diagenesis. In the copper deposit area, the orebody distributes in the strata of the Baogutu and Xibeikulasi group, and the ground surface is covered by tuffaceous siltstone. The clear structure of the copper deposit has not been revealed yet. In this paper, we utilize the technique of ambient noise tomography (ANT) to image the phase velocity anomaly maps of different frequencies in the deposit area. Then, we invert the shear (S-) wave velocity structures by using a damped least squares inversion algorithm. The pattern of the tomographic images indicates that the copper deposit mainly distributes in the range of 0.3-0.5 km depth. The major orebody is identified as an obviously high-velocity anomaly. In addition, a small high-velocity anomaly is observed at a depth greater than 0.4 km in the northeast of the study area, and it might associate with another orebody of the Baogutu copper deposit, which has not previously been reported.

  18. Fluid inclusion study of the Fiumarella barite deposit (Catanzaro — S. Italy)

    NASA Astrophysics Data System (ADS)

    Buchanan, L. J.; de Vivo, B.; Kramer, A. K.; Lima, A.

    1981-08-01

    Samples from a barite vein deposit, located in the Catanzaro Fiumarella (Calabria) were examined by fluid inclusion and ore minerographic techniques. The barite vein occur in plutonic rocks of the Stilo Unit, where some Mo mineralizations were reported. The purpose of the study was to determine the characteristics of the fluid inclusions and to compare them to those of typical porphyry Cu/Mo systems. The ore minerographic study shows that the sulfides, associated to the barite, are clearly post-barite. The fluid inclusion results indicate that the average minimum temperature of the barite formation can be assumed to be about 210°C, with a range of 190 235°C. The salinity of the barite forming solutions is in the range 0 19.5 wt% NaCl and the average minimum pressure on the system was of 18.04 bars equivalent to a minimum depth of 201 m of barite formation below the paleowatertable. No genetic link is suggested to exist between the fluid inclusions of the Fiumarella barite deposit and those characteristic of typical porphyry Cu/Mo systems, whereas a close relation with epithermal precious metal (with base metals) vein deposits or with their distant cousins, the Kuroko deposits, is suggested to exist.

  19. The Chahnaly low sulfidation epithermal gold deposit, western Makran volcanic arc, southeastern Iran

    USGS Publications Warehouse

    Sholeh, Ali; Rastad, Ebrahim; Huston, David L.; Gemmell, J. Bruce; Taylor, Ryan D.

    2016-01-01

    The Chahnaly Au deposit formed during the early stages of magmatism. LA-ICP-MS zircon U-Pb geochronology of host andesite and 40Ar/39Ar dating of two samples of gold-associated adularia show that the ore-stage adularia (19.83 ± 0.10 and 19.2 ± 0.5 Ma) is younger, by as much as 1.5 million years, than the volcanic host rock (20.32 ± 0.4 Ma). Therefore, either hydrothermal activity continued well after volcanism or a second magmatic event rejuvenated hydrothermal activity. This second magmatic event may be related to eruption of porphyritic andesite at ~20.32 ± 0.40 Ma, which is within error of ~19.83 ± 0.10 Ma adularia. The new LA-ICP-MS zircon U-Pb host rock and vein adularia 40Ar/39Ar ages suggest that early Miocene magmatism and mineralization in the Bazman area is of a similar age to that of the Saindak porphyry and Tanjeel porphyry center of the giant Reko Diq deposit. This confirms the existence of early Miocene arc magmatism and mineralization along the Iranian part of the Makran volcanic arc. Ore, alteration mineralogy, and alteration patterns indicate that the Chahnaly deposit is a typical low-sulfidation epithermal Au deposit, located in a poorly explored part of the Makran volcanic arc in Iran.                   

  20. Utility of high-altitude infrared spectral data in mineral exploration: Application to Northern Patagonia Mountains, Arizona

    USGS Publications Warehouse

    Berger, B.R.; King, T.V.V.; Morath, L.C.; Phillips, J.D.

    2003-01-01

    Synoptic views of hydrothermal alteration assemblages are of considerable utility in regional-scale minerals exploration. Recent advances in data acquisition and analysis technologies have greatly enhanced the usefulness of remotely sensed imaging spectroscopy for reliable alteration mineral assemblages mapping. Using NASA's Airborne Visible Infrared Imaging Spectrometer (AVIRIS) sensor, this study mapped large areas of advanced argillic and phyllic-argillic alteration assemblages in the southeastern Santa Rita and northern Patagonia mountains, Arizona. Two concealed porphyry copper deposits have been identified during past exploration, the Red Mountain and Sunnyside deposits, and related published hydrothermal alteration zoning studies allow the comparison of the results obtained from AVIRIS data to the more traditional field mapping approaches. The AVIRIS mapping compares favorably with field-based studies. An analysis of iron-bearing oxide minerals above a concealed supergene chalcocite deposit at Red Mountain also indicates that remotely sensed data can be of value in the interpretation of leached caps above porphyry copper deposits. In conjunction with other types of geophysical data, AVIRIS mineral maps can be used to discriminate different exploration targets within a region.

  1. Computer finds ore

    NASA Astrophysics Data System (ADS)

    Bell, Peter M.

    Artificial intelligence techniques are being used for the first time to evaluate geophysical, geochemical, and geologic data and theory in order to locate ore deposits. After several years of development, an intelligent computer code has been formulated and applied to the Mount Tolman area in Washington state. In a project funded by the United States Geological Survey and the National Science Foundation a set of computer programs, under the general title Prospector, was used successfully to locate a previously unknown ore-grade porphyry molybdenum deposit in the vicinity of Mount Tolman (Science, Sept. 3, 1982).The general area of the deposit had been known to contain exposures of porphyry mineralization. Between 1964 and 1978, exploration surveys had been run by the Bear Creek Mining Company, and later exploration was done in the area by the Amax Corporation. Some of the geophysical data and geochemical and other prospecting surveys were incorporated into the programs, and mine exploration specialists contributed to a set of rules for Prospector. The rules were encoded as ‘inference networks’ to form the ‘expert system’ on which the artificial intelligence codes were based. The molybdenum ore deposit discovered by the test is large, located subsurface, and has an areal extent of more than 18 km2.

  2. Selenium content in sulfide ores from the Chalkidiki peninsula, Greece.

    PubMed

    Nicolaidou, A E

    1998-01-01

    Selenium (Se) was assessed in galena, sphalerite, and pyrite samples. These are components of mixed sulfide ores from the Olympias and Madem Lakkos-Mavres Petres deposits and the Skouries porphyry-copper deposit. We used atomic absorption spectroscopy (AAS) with a hydride generator system. The highest concentration of Se (516 ppm) was found in the fine-grained galena at the -135 level of the Olympias deposits. In the Madem Lakkos-Mavres Petres deposit, the highest concentration of Se (33 ppm) was found in the pyrites of the level 30. The concentration of Se in the arsenopyrites and chalcopyrites is lower than the detection limit of the analytical method (< 100 ppb). The concentrated chalcopyrite from the porphyry copper deposit at Skouries exhibits a significant Se content (average 200 ppm) in contrast to the chalcopyrite from the Olympias and the Madem Lakkos-Mavres Petres. Variations in the Se content of the sulfide minerals studied could be caused by redox-pH and/or temperature conditions, as well as by the difference in crystal structure. The Se found in the areas studied may positively affect the environment. Sulfide minerals are oxidized by microorganisms, infiltrate in the soil-water in the form of selenate or selenite ion, and directly or indirectly influence the human organism.

  3. Tertiary tilting and dismemberment of the laramide arc and related hydrothermal systems, Sierrita Mountain, Arizona

    USGS Publications Warehouse

    Stavast, W.J.A.; Butler, R.P.; Seedorff, E.; Barton, M.D.; Ferguson, C.A.

    2008-01-01

    Multiple lines of evidence, including new and published geologic mapping and paleomagnetic and geobarometric determinations, demonstrate that the rocks and large porphyry copper systems of the Sierrita Mountains in southern Arizona were dismembered and tilted 50?? to 60?? to the south by Tertiary normal faulting. Repetition of geologic features and geobarometry indicate that the area is segmented into at least three major structural blocks, and the present surface corresponds to oblique sections through the Laramide plutonic-hydrothermal complex, ranging in paleodepth from ???1 to ???12 km. These results add to an evolving view of a north-south extensional domain at high angles to much extension in the southern Basin and Range, contrast with earlier interpretations that the Laramide systems are largely upright and dismembered by thrust faults, highlight the necessity of restoring Tertiary rotations before interpreting Laramide structural and hydrothermal features, and add to the broader understanding of pluton emplacement and evolution of porphyry copper systems. ?? 2008 Society of Economic Geologists, Inc.

  4. Discrimination of hydrothermally altered rocks along the Battle Mountain-Eureka, Nevada mineral belt using LANDSAT images

    NASA Technical Reports Server (NTRS)

    Krohn, M. D.; Abrams, M. J.; Rowan, L. C. (Principal Investigator)

    1979-01-01

    The author has identified the following significant results. Limonitic alteration halos associated with two copper prophyry deposits were successfully mapped at Battle Mountain. Alteration halos from both a hypogene system at Copper Canyon and a supergene system at Copper Basin are recognizable in the composite. Both copper porphyry deposits are located in sedimentary rock units that commonly have ferruginous coatings; yet, in most cases, the hydrothermally derived limonite was distinguishable in the CRC from sedimentary limonite. Large format playback images with pixel sizes from 200 to 400 micron m provided details of spatial resolution and color separation unachievable on enlargements from 70 mm film chips. Details of the alteration halos could be resolved only in the large format images. Two aspects of the alteration halos of the porphyry copper deposits were not mapped on the CRC. The optimum CRC image for the area studied consists of MSS 4/5 as blue, MSS 4/6 as yellow, and MSS 6/7 as magenta using diazo films. The disseminated gold deposits at Gold Acres are not depicted in the CRC image.

  5. Statistical methods of estimating mining costs

    USGS Publications Warehouse

    Long, K.R.

    2011-01-01

    Until it was defunded in 1995, the U.S. Bureau of Mines maintained a Cost Estimating System (CES) for prefeasibility-type economic evaluations of mineral deposits and estimating costs at producing and non-producing mines. This system had a significant role in mineral resource assessments to estimate costs of developing and operating known mineral deposits and predicted undiscovered deposits. For legal reasons, the U.S. Geological Survey cannot update and maintain CES. Instead, statistical tools are under development to estimate mining costs from basic properties of mineral deposits such as tonnage, grade, mineralogy, depth, strip ratio, distance from infrastructure, rock strength, and work index. The first step was to reestimate "Taylor's Rule" which relates operating rate to available ore tonnage. The second step was to estimate statistical models of capital and operating costs for open pit porphyry copper mines with flotation concentrators. For a sample of 27 proposed porphyry copper projects, capital costs can be estimated from three variables: mineral processing rate, strip ratio, and distance from nearest railroad before mine construction began. Of all the variables tested, operating costs were found to be significantly correlated only with strip ratio.

  6. Tectonic and magmatic controls on the metal composition of some cenozoic hydrothermal systems of the northwestern US

    SciTech Connect

    Margolis, J. . Dept. of Geological Sciences)

    1993-04-01

    Many Cenozoic, Au-Ag-rich, hydrothermal systems in the northwestern US have formed in two distinct magmatic and tectonic environments: (1) andesitic volcanic piles'' or arcs yield intrusion-related, porphyry-style Cu-Mo-B mineralization and acid-sulfate, advanced argillic alteration; base-metal rich (Pb-Zn-Ag-Ba-Au-Mn), adularia-sericite, epithermal veins form in the peripheral propylitically-altered areas; and (2) Au-Se-Sb-As[+-]Ag-rich, Pb-Zn-Ba-Mn poor, adularia-sericite epithermal deposits in rhyolitic (commonly ash-flow tuffs), andesitic, and locally bimodal volcanic terrains undergoing significant extension or transtension. Porphyry Cu-Mo mineralization, acid-sulfate/advanced-argillic alteration, and base-metal rich veins are apparently absent in the second/environment, possibly owing in part to smaller amounts of magmatic volatiles entering the hydrothermal system. Examples of type 1 are the Miocene Cascades in WA and OR (e.g., Bohemia district) and the Miocene Virginia Range in NW Nevada (Washington Hill and Comstock districts). Examples of type 2 are the deposits at Republic and Wenatchee, WA, which formed during extension in the Eocene; DeLamar, ID and Sleeper, NV, which formed during the onset of rapid Basin and Range extension following Mid Miocene flood-basalt activity; and Wind Mtn., Sulfur, Florida Canyon, and possibly Rosebud, NV.

  7. Metallogeny of the northeastern Pacific Rim: an example of the distribution of ore deposits along a growing continental margin

    USGS Publications Warehouse

    Goldfarb, R.J.; Hart, C.J.; Mortensen, J.K.; Weber, Graeme

    1999-01-01

    The distribution of mineral deposits within northwestern North America (Alaska, Yukon, and northern British Columbia) allows for an in-depth examination of the metallogenic patterns of a growing continental margin. A more complete understanding of the tectonic evolution of this part of the Pacific Rim, achieved over the last 15 to 20 years, now allows for the placement of ore systems into a well-defined plate tectonic framework. Ore deposits older than about 185 Ma represent hydrothermal systems that were active in the platform/shelf environment of ancestral North America's miogeocline or hydrothermal systems developed in oceanic arcs and continental fragments more distal to the craton. These include important SEDEX, VMS, and pre-accretionary porphyry deposits. In contrast, most mineral deposits younger than about 185 Ma were formed within the growing Cordilleran orogen, as terranes were accreted to the continental margin during interactions between the North America and Pacific/Farallon/Kula plates. Such syn- to post-accretionary mineralised systems include many large lode gold and porphyry/skarn systems.

  8. Modal Petrology and Geostatistics of the Blue Hills Igneous Complex, Boston, Massachusetts, by Rietveld X-ray Diffraction: Multi-scalar Investigation of Volcanic and Intrusive Relationships

    NASA Astrophysics Data System (ADS)

    Besancon, J. R.; Spence, T. M.

    2004-12-01

    The Blue Hills Igneous Complex of eastern Massachusetts consists of mildly peralkaline volcanic and intrusive units including the Quincy Granite, the Blue Hills Porphyry, and a set of mainly pyroclastic rhyolite flow units traditionally called the Aporhyolite. Similar whole-rock chemistry has led most workers to assume that they are related rocks, despite some unclear field relationships. Kaktins (1976) divided the volcanic rocks into six units, but buried contacts do not permit confidence in either their number or stratigraphic position. To test a new method of modal analysis of these rocks, thirty-five samples were crushed, ground to approximately 5 micrometers, spray-dried to produce randomly oriented powder, and analyzed by x-ray diffraction. A constant eleven-phase Rietveld starting model was applied to the x-ray spectra, and then refined to produce a modal database of phase proportions in each sample. Geostatistical analysis with GIS software delineates a number of trends, with statistical measures of uncertainty. Aegirine in volcanics decreases in abundance with distance south from the E-W contact of volcanic rocks and granite. Riebeckite is found in the granite (both as veins and as apparently magmatic crystals) and the porphyry, but is less abundant or absent among the volcanic rocks. Where both amphibole and pyroxene are present, they are negatively correlated. The goal is to develop an additional tool for correlation of volcanic rocks, one based on mineral proportions in both aphanitic and phaneritic rocks.

  9. Mineral resources of high-tech metals in Russia: State of the art and outlook

    NASA Astrophysics Data System (ADS)

    Bortnikov, N. S.; Volkov, A. V.; Galyamov, A. L.; Vikent'ev, I. V.; Aristov, V. V.; Lalomov, A. V.; Murashov, K. Yu.

    2016-03-01

    Seven main ore-forming systems—porphyry and epithermal; orogenic related to granitic intrusions; magmatic ultramafic; volcanic-hosted massive sulfide and volcanic-sedimentary; sedimentary basins; related to alkaline magmatic activity; and placers and weathering mantles—are sources of high-tech critical metals. The following promising types of ore deposits containing high-tech critical metals as by-products are recognized: Cu-Mo porphyry, Fe-Cu-Au and Pb-Zn skarn, base-metal epithermal, volcanic-hosted massive sulfide, base-metal stratiform, various tin deposits, and placers containing rare metals including REE. The mineral resources of critical metals in Russia are compared with those known in other countries. The contents of high-tech critical metals in ores of some noble-metal deposits of the Russian Northeast are reported. It is shown that the subsurface of Russia possesses considerable mineral resource potential for hightech critical metals, which allows new enterprises to be created or production of operating enterprises to increase.

  10. Geochemical evidence for a brooks range mineral belt, Alaska

    USGS Publications Warehouse

    Marsh, S.P.; Cathrall, J.B.

    1981-01-01

    Geochemical studies in the central Brooks Range, Alaska, delineate a regional, structurally controlled mineral belt in east-west-trending metamorphic rocks and adjacent metasedimentary rocks. The mineral belt extends eastward from the Ambler River quadrangle to the Chandalar and Philip Smith quadrangles, Alaska, from 147?? to 156??W. longitude, a distance of more than 375 km, and spans a width from 67?? to 69??N. latitude, a distance of more than 222 km. Within this belt are several occurrences of copper and molybdenum mineralization associated with meta-igneous, metasedimentary, and metavolcanic rocks; the geochemical study delineates target areas for additional occurrences. A total of 4677 stream-sediment and 2286 panned-concentrate samples were collected in the central Brooks Range, Alaska, from 1975 to 1979. The -80 mesh ( 2.86) nonmagnetic fraction of the panned concentrates from stream sediment were analyzed by semiquantitative spectrographic methods. Two geochemical suites were recognized in this investigation; a base-metal suite of copper-lead-zinc and a molybdenum suite of molybdenum-tin-tungsten. These suites suggest several types of mineralization within the metamorphic belt. Anomalies in molybdenum with associated Cu and W suggest a potential porphyry molybdenum system associated with meta-igneous rocks. This regional study indicates that areas of metaigneous rocks in the central metamorphic belt are target areas for potential mineralized porphyry systems and that areas of metavolcanic rocks are target areas for potential massive sulfide mineralization. ?? 1981.

  11. Potential Of Light Pipes System In Malaysian Climate

    NASA Astrophysics Data System (ADS)

    Abd Kadir, Aslila; Hakim Ismail, Lokman; Kasim, Narimah; Kaamin, Masiri

    2016-11-01

    Light-pipes system are simple structures that allow the transmission of daylight from the outside to the inside of a room. It is a practical application in many buildings where daylight cannot reach due to building design and limited facade to placing windows. Since roof is the element directly exposed to the sunlight, light pipes system could be introduced. This paper examines the illumination levels obtained using light pipes system under Malaysia climate conditions. A light-pipe system that was installed in a test room located in Batu Pahat. Indoor illuminance distributions and concurrent outdoor illuminance were monitored at a 30 minutes interval for 5 days. The results indicated that the amount of daylight penetrated into the building are varied with less than 150lux in the early morning and late evening, and maximum at over 350lux in the noon and early afternoon. The average internal illuminance levels offer by light pipe system met the MS 1525:2007 recommendation for application in Malaysian buildings. These findings indicated that the light pipe system has a potential as a tool for introducing daylight indoors in Malaysia.

  12. Prosthetic restoration in patient with incomplete spinal cord injury.

    PubMed

    Mustafah, Nadia Mohd; Bakar, Noriani Abu; Yang, Chung Tze

    2016-01-01

    We describe a case of 55-years-old man with a known T11 AIS C since 1985. The muscle strength of his left leg is better than the right leg and he is an active community ambulator. He walks using his right knee ankle foot orthosis without a knee lock. However, on April 2012 he had undergone a left transtibial amputation secondary to infected diabetic foot ulcer. He only had his first contact with rehabilitation team 2 months after the amputation and started on gait retraining since. Given the fact that he is a K3 level as he used to climb Batu Caves which is known to have 272 steps and he plans to continue this activity for his religious purposes, we prescribed him with prosthesis - patella tendon bearing socket, pin and lock suspension, silicone liner and energy storing foot. In conclusion, a community ambulator in dual disabilities, that is, spinal cord injury and amputee is hardly encountered due to multiple confounding factors. However, the right prosthetic prescription in patient with good prognosticating factors to ambulate will determine successful rehabilitation.

  13. Field incidence on Brontispa longissima (Gestro), an invasive pest of coconut

    NASA Astrophysics Data System (ADS)

    Khairul, Anuar W. A. Wan; Idris, A. B.

    2013-11-01

    The Coconut Leaf Beetle, Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae) is one the most serious pests of coconut palms. This study was aimed to investigate the field incidence of Brontispa longissima infestation at Department of Agricultural, Parit Botak, Batu Pahat, Johor. B. longissima were collected from infested coconut and other palms and reared in the laboratory at MARDI, Serdang under ambient condition. The field incidence on the common varieties of coconut especially matag, pandan, tagnanan and other palms, oil palm were assessed. There was a significant difference in the mean percentage of leaf damage among palm varieties in the field (P<0.05). The pandan variety had the highest (40.93±0.91) mean of percentage leaf damage compared to matag (38.92±0.90), tagnanan (33.64±0.86) and oil palm (0±0.00). There was a significant (P<0.05) interactions between varieties and month on percentage of leaf damage in the field. The damaged incidence was highest in March and that the damage on pandan leaf was significantly (72.55±2.05) higher on matag (70.03±2.16), tagnanan (55.68±2.96) and oil palm (0±0.00).

  14. Characterization and evaluation of novel film forming polymer for drug delivery.

    PubMed

    Mundada, Artish; Satturwar, Prashant; Fulzele, Suniket; Joshi, Sudhir; Dorle, Avinash

    2011-01-01

    DB is a whitish to yellowish resin, characterized initially in terms of solubility, acid value, molecular weight (Mw), polydispersity index (Mw/Mn) and glass transition temperature (Tg). Neat plasticized films of DB (Damar Batu) are investigated for mechanical, water vapor transmission and moisture absorption properties. To improve the mechanical properties of the free films dibutyl sebacate, a hydrophobic plasticizer was added to film composition. The biomaterial was further investigated for sustaining the drug release from spherical units (multiparticulates). The core of pellet was prepared using Diclofenac sodium (10% w/w) as a model drug by extrusion and speronization. The drug containing pellets were coated using DB plasticized film-coating solutions. With 2% coat build-up, sustained drug release up to 10 h was achieved with coating solution containing 20% and 30% w/w (based on DB weight) plasticizers. Less than 3% drug was released in the first 2 h which may be explained in terms of the insolubility of DB and the drug in acidic milieu. The release from pellets coated using DB film coating solution containing 20% and 30% plasticizers followed first order release pattern. DB seems to be a promising film former for pharmaceutical coating due to its reasonably good mechanical properties, low water vapor transmission and sustained release capability.

  15. First discovery of Pleistocene orangutan (Pongo sp.) fossils in Peninsular Malaysia: biogeographic and paleoenvironmental implications.

    PubMed

    Ibrahim, Yasamin Kh; Tshen, Lim Tze; Westaway, Kira E; Cranbrook, Earl Of; Humphrey, Louise; Muhammad, Ros Fatihah; Zhao, Jian-xin; Peng, Lee Chai

    2013-12-01

    Nine isolated fossil Pongo teeth from two cave sites in Peninsular Malaysia are reported. These are the first fossil Pongo specimens recorded in Peninsular Malaysia and represent significant southward extensions of the ancient Southeast Asian continental range of fossil Pongo during two key periods of the Quaternary. These new records from Peninsular Malaysia show that ancestral Pongo successfully passed the major biogeographical divide between mainland continental Southeast Asia and the Sunda subregion before 500 ka (thousand years ago). If the presence of Pongo remains in fossil assemblages indicates prevailing forest habitat, then the persistence of Pongo at Batu Caves until 60 ka implies that during the Last Glacial Phase sufficient forest cover persisted in the west coast plain of what is now Peninsular Malaysia at least ten millennia after a presumed corridor of desiccation had extended to central and east Java. Ultimately, environmental conditions of the peninsula during the Last Glacial Maximum evidently became inhospitable for Pongo, causing local extinction. Following post-glacial climatic amelioration and reforestation, a renewed sea barrier prevented re-colonization from the rainforest refugium in Sumatra, accounting for the present day absence of Pongo in apparently hospitable lowland evergreen rainforest of Peninsular Malaysia. The new teeth provide further evidence that Pongo did not undergo a consistent trend toward dental size reduction over time.

  16. Shoreline Delineation and Land Reclamation Change Detection Using Landsat Image

    NASA Astrophysics Data System (ADS)

    Rosli, M. I.; Ahmad, M. A.; Kaamin, M.; Izhar, M. F. N.

    2016-07-01

    This study is conducted on the usage of remote sensing images from several different years in order to analyze the changes of shoreline and land cover of the area. Remote sensing images used in this study are the data captured by the Landsat satellite. The images are projecting the land surface in 30 by 30 meter resolution and it is processed by the ENVI software. ENVI is able to change each digital number of the pixels on the images into specific value according to the applied model for classification in which could be used as an approach in calculating the area different classes based from the images itself. Therefore, using this method, the changes on the coastal area are possible to be determined. Analysis of the shoreline and land reclamation around the coastal area is integrated with the land use changes to determine its impact. The study shows that Batu Pahat area might have undergone land reclamation whereas in Pasir Gudang is experiencing substantial amount of erosion. Besides, the changes of land use in both areas were considered to be rapid and due to the results obtained from this study, the issues may be brought about for the local authority awareness action.

  17. Application of geophysical techniques for 3D geohazard mapping to delineate cavities and potential sinkholes in the northern part of Kuala Lumpur, Malaysia.

    PubMed

    Bakhshipour, Zeinab; Huat, Bujang B K; Ibrahim, Shaharin; Asadi, Afshin; Kura, Nura Umar

    2013-01-01

    This work describes the application of the electrical resistivity (ER) method to delineating subsurface structures and cavities in Kuala Lumpur Limestone within the Batu Cave area of Selangor Darul Ehsan, Malaysia. In all, 17 ER profiles were measured by using a Wenner electrode configuration with 2 m spacing. The field survey was accompanied by laboratory work, which involves taking resistivity measurements of rock, soil, and water samples taken from the field to obtain the formation factor. The relationship between resistivity and the formation factor and porosity for all the samples was established. The porosity values were plotted and contoured. A 2-dimensional and 3-dimensional representation of the subsurface topography of the area was prepared through use of commercial computer software. The results show the presence of cavities and sinkholes in some parts of the study area. This work could help engineers and environmental managers by providing the information necessary to produce a sustainable management plan in order to prevent catastrophic collapses of structures and other related geohazard problems.

  18. The Population Size of the Lesser Bandicoot (Bandicota bengalensis) in Three Markets in Penang, Malaysia

    PubMed Central

    Khairuddin, Nurul Liyana; Raghazli, Razlina; Sah, Shahrul Anuar Mohd; Shafie, Nur Juliani; Azman, Nur Munira

    2011-01-01

    A study of the population size of Bandicota bengalensis rats in three markets in Penang was conducted from April 2004 through May 2005. Taman Tun Sardon Market (TTS), Batu Lanchang Market (BTLG) and Bayan Lepas Market (BYNLP) were surveyed. Six sampling sessions were conducted in each market for four consecutive nights per session. The total captures of B. bengalensis in TTS, BTLG and BYNLP were 92%, 73% and 89% respectively. The total population of B. bengalensis in TTS was estimated as 265.4 (with a 95% confidence interval of 180.9–424.2). The total population at BTLG was estimated as 69.9 (with a 95% confidence interval of 35.5–148.9). At BYNLP, the total population was estimated as 134.7 (with a 95% confidence interval of 77.8–278.4). In general, adult male rats were captured most frequently at each site (55.19%), followed by adult females (31.69%), juvenile males (9.84%) and juvenile females (3.27%). The results showed that the number of rats captured at each site differed significantly according to sex ratio and maturity (χ2 = 121.45, df = 3, p<0.01). Our results suggest that the population sizes found by the study may not represent the actual population size in each market owing to the low numbers of rats recaptured. This finding might have resulted from the variety of foods available in the markets. PMID:24575219

  19. Population density of oil palm pollinator weevil Elaeidobius kamerunicus based on seasonal effect and age of oil palm

    NASA Astrophysics Data System (ADS)

    Daud, Syarifah Nadiah Syed Mat; Ghani, Idris Abd.

    2016-11-01

    The pollinating weevil, Elaedobius kamerunicus (EK) has been known to be the most efficient insect pollinator of oil palm, and has successfully improved the oil palm pollination and increased the yield. Its introduction has greatly reduced the need for assisted pollination. The purpose of this study was to identify the population density of oil palm pollinator weevil EK using the concept of pollinator force and to relate the population density with the seasonal effect and the age of oil palm at Lekir Oil Palm Plantation Batu 14, Perak, Peninsular Malaysia. The pollinator force of the weevil was sustained at a range between 3095.2 to 19126.1 weevils per ha. The overall mean of weevil per spikelet shows that the range of weevil was between 13.51 and 54.06 per spikelet. There was no correlation between rainfall and population density of EK. However, positive correlation was obtained between weevil density and the number of anthesising female inflorescence of oil palm (r= 0.938, p< 0.05). Results of t-test show that the 6-year old oil palm stands had significantly different population density than that of a 8-year old oil palm stand. The information of this study should be useful as a baseline data to investigate why there is such a wide range of weevils per ha or spikelet. Further study should also be done to relate the number pollinator force per spikelete and the Fresh fruit Bunch (FFB), fruit set or fruit to bunch ratio.

  20. Prosthetic restoration in patient with incomplete spinal cord injury

    PubMed Central

    Mustafah, Nadia Mohd; Bakar, Noriani Abu; Yang, Chung Tze

    2016-01-01

    We describe a case of 55-years-old man with a known T11 AIS C since 1985. The muscle strength of his left leg is better than the right leg and he is an active community ambulator. He walks using his right knee ankle foot orthosis without a knee lock. However, on April 2012 he had undergone a left transtibial amputation secondary to infected diabetic foot ulcer. He only had his first contact with rehabilitation team 2 months after the amputation and started on gait retraining since. Given the fact that he is a K3 level as he used to climb Batu Caves which is known to have 272 steps and he plans to continue this activity for his religious purposes, we prescribed him with prosthesis – patella tendon bearing socket, pin and lock suspension, silicone liner and energy storing foot. In conclusion, a community ambulator in dual disabilities, that is, spinal cord injury and amputee is hardly encountered due to multiple confounding factors. However, the right prosthetic prescription in patient with good prognosticating factors to ambulate will determine successful rehabilitation. PMID:28053733

  1. Geological implications of new biostratigraphic data from East and West Kalimantan, Indonesia

    NASA Astrophysics Data System (ADS)

    Moss, S. J.; Finch, E. M.

    1997-12-01

    This paper presents palaeontological ages based on new nannofossil and foraminiferal studies from a range of sedimentary rocks from the provinces of West and East Kalimantan, Indonesia. The age of sedimentary rocks in Kalimantan, away from the main hydrocarbon exploration areas of the coastal regions, represents a major gap in our basic knowledge of the island of Borneo. The implications of these new results and existing and new correlations are reviewed and suggested. In particular, the base of the Tertiary section in the Kutai Basin is shown to be upper Middle Eocene in age, rather than Late Eocene as originally thought. The limestones of the Batu Belah member of the Ujoh Bilang Formation are dated as NP24-25, Late Oligocene, rather than Early Oligocene as earlier work had suggested. In the western part of the Mangkalihat Peninsula area the base of the Tertiary section is determined to be Late Oligocene. Various basement units from both East and West Kalimantan contained Late Jurassic to Late Cretaceous microfossils.

  2. Spatial Analysis in Determination Of Flood Prone Areas Using Geographic Information System and Analytical Hierarchy Process at Sungai Sembrong's Catchment

    NASA Astrophysics Data System (ADS)

    Bukari, S. M.; Ahmad, M. A.; Wai, T. L.; Kaamin, M.; Alimin, N.

    2016-07-01

    Floods that struck Johor state in 2006 and 2007 and the East Coastal in 2014 have triggered a greatly impact to the flood management here in Malaysia. Accordingly, this study conducted to determine potential areas of flooding, especially in Batu Pahat district since it faces terrifying experienced with heavy flood. This objective is archived by using the application of Geographic Information Systems (GIS) on study area of flood risk location at the watershed area of Sungai Sembrong. GIS functions as spatial analysis is capable to produce new information based on analysis of data stored in the system. Meanwhile the Analytical Hierarchy Process (AHP) was used as a method for setting up in decision making concerning the existing data. By using AHP method, preparation and position of the criteria and parameters required in GIS are neater and easier to analyze. Through this study, a flood prone area in the watershed of Sungai Sembrong was identified with the help of GIS and AHP. Analysis was conducted to test two different cell sizes, which are 30 and 5. The analysis of flood prone areas were tested on both cell sizes with two different water levels and the results of the analysis were displayed by GIS. Therefore, the use of AHP and GIS are effective and able to determine the potential flood plain areas in the watershed area of Sungai Sembrong.

  3. Development of chloroplast simple sequence repeats (cpSSRs) for the intraspecific study of Gracilaria tenuistipitata (Gracilariales, Rhodophyta) from different populations

    PubMed Central

    2014-01-01

    Background Gracilaria tenuistipitata is an agarophyte with substantial economic potential because of its high growth rate and tolerance to a wide range of environment factors. This red seaweed is intensively cultured in China for the production of agar and fodder for abalone. Microsatellite markers were developed from the chloroplast genome of G. tenuistipitata var. liui to differentiate G. tenuistipitata obtained from six different localities: four from Peninsular Malaysia, one from Thailand and one from Vietnam. Eighty G. tenuistipitata specimens were analyzed using eight simple sequence repeat (SSR) primer-pairs that we developed for polymerase chain reaction (PCR) amplification. Findings Five mononucleotide primer-pairs and one trinucleotide primer-pair exhibited monomorphic alleles, whereas the other two primer-pairs separated the G. tenuistipitata specimens into two main clades. G. tenuistipitata from Thailand and Vietnam were grouped into one clade, and the populations from Batu Laut, Middle Banks and Kuah (Malaysia) were grouped into another clade. The combined dataset of these two primer-pairs separated G. tenuistipitata obtained from Kelantan, Malaysia from that obtained from other localities. Conclusions Based on the variations in repeated nucleotides of microsatellite markers, our results suggested that the populations of G. tenuistipitata were distributed into two main geographical regions: (i) populations in the west coast of Peninsular Malaysia and (ii) populations facing the South China Sea. The correct identification of G. tenuistipitata strains with traits of high economic potential will be advantageous for the mass cultivation of seaweeds. PMID:24490797

  4. The Distribution and Conservation Status of Green Turtles (Chelonia mydas) and Olive Ridley Turtles (Lepidochelys olivacea) on Pulau Pinang beaches (Malaysia), 1995-2009.

    PubMed

    Salleh, Sarahaizad Mohd; Yobe, Mansor; Sah, Shahrul Anuar Mohd

    2012-05-01

    The Green Turtle (Chelonia mydas) and Olive Ridley Turtle (Lepidochelys olivacea) are the only sea turtles with recorded landings in the Pulau Pinang coastal area. The Green Turtle has been the most abundant and widely distributed sea turtle in this area since it was first surveyed in 1995. Statistical analysis by the Pulau Pinang Department of Fisheries on the distribution of sea turtles from 2001 through 2009 has identified Pantai Kerachut and Telok Kampi as the most strongly preferred beaches for Green Turtle landings, with records for almost every month in every year. Green Turtle tracks and nests have also been found along the coast of Pulau Pinang at Batu Ferringhi, Tanjong Bungah, Pantai Medan, Pantai Belanda, Telok Kumbar, Gertak Sanggul, Moonlight Beach, Telok Duyung, Telok Aling, Telok Bahang and Telok Katapang. The Olive Ridley Turtle is present in smaller numbers; landing and nesting have only been recorded on a few beaches. There are no previous records of Olive Ridley landings at Pantai Kerachut and Telok Kampi, but tracks and nests have been found at Telok Kumbar, Tanjong Bungah, Pantai Medan, Telok Duyung and Gertak Sanggul. A Turtle Conservation Centre has been established at Pantai Kerachut to protect these species from extinction in Pulau Pinang. This paper presents details of the records and distribution of sea turtles in Pulau Pinang from 1995 through 2009.

  5. Characterization and Evaluation of Novel Film Forming Polymer for Drug Delivery

    PubMed Central

    Mundada, Artish; Satturwar, Prashant; Fulzele, Suniket; Joshi, Sudhir; Dorle, Avinash

    2011-01-01

    DB is a whitish to yellowish resin, characterized initially in terms of solubility, acid value, molecular weight (Mw), polydispersity index (Mw/Mn) and glass transition temperature (Tg). Neat plasticized films of DB (Damar Batu) are investigated for mechanical, water vapor transmission and moisture absorption properties. To improve the mechanical properties of the free films dibutyl sebacate, a hydrophobic plasticizer was added to film composition. The biomaterial was further investigated for sustaining the drug release from spherical units (multiparticulates). The core of pellet was prepared using Diclofenac sodium (10% w/w) as a model drug by extrusion and speronization. The drug containing pellets were coated using DB plasticized film-coating solutions. With 2% coat build-up, sustained drug release up to 10 h was achieved with coating solution containing 20% and 30% w/w (based on DB weight) plasticizers. Less than 3% drug was released in the first 2 h which may be explained in terms of the insolubility of DB and the drug in acidic milieu. The release from pellets coated using DB film coating solution containing 20% and 30% plasticizers followed first order release pattern. DB seems to be a promising film former for pharmaceutical coating due to its reasonably good mechanical properties, low water vapor transmission and sustained release capability. PMID:24363678

  6. BBIS: Beacon Bus Information System

    NASA Astrophysics Data System (ADS)

    Kasim, Shahreen; Hafit, Hanayanti; Pei Juin, Kong; Afizah Afif, Zehan; Hashim, Rathiah; Ruslai, Husni; Jahidin, Kamaruzzaman; Syafwan Arshad, Mohammad

    2016-11-01

    Lack of bus information for example bus timetable, status of the bus and messy advertisement on bulletin board at the bus stop will give negative impact to tourist. Therefore, a real-time update bus information bulletin board provides all information needed so that passengers can save their bus information searching time. Supported with Android or iOS, Beacon Bus Information System (BBIS) provides bus information between Batu Pahat and Kluang area. BBIS is a system that implements physical web technology and interaction on demand. It built on Backend-as-a-Service, a cloud solution and Firebase non relational database as data persistence backend and syncs between user client in the real-time. People walk through bus stop with smart device and do not require any application. Bluetooth Beacon is used to achieve smart device's best performance of data sharing. Intellij IDEA 15 is one of the tools that that used to develop the BBIS system. Multi-language included front end and backend supported Integration development environment (IDE) helped to speed up integration process.

  7. Magmatic-hydrothermal origin of the early Triassic Laodou lode gold deposit in the Xiahe-Hezuo district, West Qinling orogen, China: implications for gold metallogeny

    NASA Astrophysics Data System (ADS)

    Jin, Xiao-ye; Li, Jian-wei; Hofstra, Albert H.; Sui, Ji-xiang

    2016-12-01

    The Xiahe-Hezuo district in the West Qinling orogen contains numerous Au-(As-Sb) and Cu-Au-(W) deposits. The district is divided into eastern and western zones by the Xiahe-Hezuo Fault. The western zone is exposed at a shallow level and contains sediment-hosted disseminated Au-(As-Sb) deposits, whereas the eastern zone is exposed at a deeper level and contains Cu-Au-(W) skarn and lode gold deposits within or close to granitic intrusions. The Laodou gold deposit in the eastern zone consists of auriferous quartz-sulfide-tourmaline and minor quartz-stibnite veins that are structurally controlled by fault zones transecting the Laodou quartz diorite porphyry stock and enveloped by potassic and phyllic alteration. Both the veins and alteration halos commonly contain quartz, sericite, tourmaline, pyrite, and arsenopyrite, with minor galena, sphalerite, chalcopyrite, tetrahedrite, and enargite. Gold occurs mainly as invisible gold in pyrite or arsenopyrite and locally as inclusions less than 50 μm in diameter. The zircon U-Pb age of 247.6 ± 1.3 Ma (2σ) on the host quartz diorite porphyry and the sericite 40Ar/39Ar plateau ages of 249.1 ± 1.6 and 249.0 ± 1.5 Ma (2σ) on two ore-related hydrothermal sericite samples are within analytical errors of one another. At the formation temperature (275 °C) inferred from microthermometric measurements of fluid inclusion, sericite and tourmaline yield calculated δDH2O values of -70 to -45‰ and δ 18OH2O of 5.8 to 9.7‰, while quartz yields calculated δ 18OH2O values of 5.1˜5.7‰. Hydrothermal tourmaline in quartz-sulfide-tourmaline veins has δ 11B of -11.2 to -0.9‰ (mean of -6.3‰) that are similar to the values of magmatic tourmaline (-8.9 to -5.5‰ with a mean of -6.8‰) in the host quartz diorite porphyry. The δ 34S values of sulfide minerals range from -5.9 to +5.8‰ with a mean of -0.6‰ that is typical of magmatic sulfur. Pyrite from hydrothermally altered quartz diorite porphyry and quartz

  8. Alpine nappe emplacement: A case study of the Suretta nappe (Graubünden, Switzerland)

    NASA Astrophysics Data System (ADS)

    Scheiber, Thomas; Pfiffner, O. Adrian

    2010-05-01

    Within this field approach on basal accretion processes we intend to get a better understanding of the stacking of crystalline basement nappes as observed in the core of many orogens. The Suretta nappe is a stack of Briançon derived lithospheric slices assembled in a south-dipping subduction zone during the Tertiary orogenic cycle. Today's axial plunge of about 30° towards ENE exposes the basal thrust over tens of kilometres and provides continuous outcrop from bottom to top of the nappe. Emphasise was laid on the frontal part of the nappe where late to post-Variscian intrusive rocks of the Rofna porphyry complex occur. Detailed structural mapping combined with microstructural analyses yield different deformation patterns of the porphyry: undeformed boudins in the interior of the nappe are generally surrounded by L-tectonites indicating WSW-ENE stretching; foliated equivalents reveal various strain intensities. Mylonites were not only detected at the base of the Suretta nappe, but also at the base of internal thrust slices overlying strongly deformed autochthonous Triassic sediments ("nappe separators") in some cases. NNW-SSE trending streching lineations persisted in zones of intense deformation. Despite the fact that shear sense indicators are generally rare, a top-to-the NNW directed transport has to be assumed. Thrusting-related deformation took place in a temperature regime of about 400°C where quartz deformed by dislocation creep and feldspar was the stronger mineral. Further intercalations of Triassic sediments in the upper parts of the nappe that could be interpreted as isoclinal folds at first sight, seem to be influenced by thrusting as well. In order to understand these fold-thrust relationships, a partial retro-deformation needs to be performed, because the Eocene top north directed stacking (Ferrera Phase after Schmid et al, 1997) predates a phase of backfolding with synchronous orogen-parallel extension (Niemet Beverin Phase). The formation of the

  9. Epithermal and plutonic gold mineralizations related to paleoproterozoic acid magmatism in the Tapajós Gold province, Amazonian craton, Brazil

    NASA Astrophysics Data System (ADS)

    Juliani, C.; Corrêa-Silva, R. H.; Monteiro, L. V.; Bettencourt, J. S.; dall Agnol, R.

    2003-04-01

    The Tapajós Gold Province (TGP) is part of the Tapajós-Parima geologic province, that includes ˜2.1 Ga volcano-sedimentary sequences (Jacareacanga Group) and the magmatic arcs of the Cuiú-Cuiú Complex (˜2.01 Ga), Creporizäo Intrusive Suite (1.97-1.95 Ga), Rio das Tropas Tonalite (˜1.90 Ga) and Parauari Intrusive Suite (˜1.88 Ga). Andesitic to rhyolitic volcanic and volcaniclastic rocks of the Iriri Group (1.88 Ga) overlie plutonic rocks and are cut by anorogenic Maloquinha Intrusive Suite (˜1.87 Ga). Paleoproterozoic fluvial to marine sequences (Buiuçú Formation), and several mafic intrusion events are also identified in the TGP. Paleoproterozoic gold mineralizations in the TGP are mainly classified as mesothermal orogenic lodes, intrusion-related gold systems, and epithermal and mesothermal lodes in shear zones. Recently, it was discovered a 1.869 Ga epithermal high-sulfidation (quartz-alunite) and low-sulfidation (adularia-sericite) gold and base metal mineralizations hosted in calc-alkaline volcanic and volcaniclastic rocks of the Iriri Group. In the high-sulfidation mineralization, hydrothermal breccias are strongly affected by high-temperature advanced argillic alteration, with alunite, natroalunite, woodhouseiite-svanbergite, andalusite, diaspore and enargite, besides argillic and propylitic hydrothermal alterations. Over the hydrothermal breccia pipe occurs a hematite-rich silica cap and in the deeper zones sericitic alteration is also present. The epithermal high- and low-sulfidation mineralizations are geneticaly linked to stocks of hydrothermalized granophyry, and rhyolitic and rhyodacitic porphyry dikes and are hosted by late ring composite volcanoes, related to evolution of nested ash-flow caldera complexes. The caldera genesis is atributed to emplacement of shalow late- to post-tectonic calc-alkaline batholits of the Parauari Intrusive Suite in back-arc rifts. The mesozonal relatively reduced Batalha Granite hosts gold mineralizations and

  10. Reconnaissance geology of the Precambrian rocks in the Ayn Qunay quadrangle, Kingdom of Saudi Arabia

    USGS Publications Warehouse

    Overstreet, William C.; Whitlow, Jesse William; Ankary, Abdullah O.

    1972-01-01

    The Aya Qunay quadrangle covers an area of 2833 sq km in central Saudi Arabia, Only the western edge of the quadrangle is underlain by Precambrian rocks, which were the subject of this investigation. Toward the east the Precambrian rocks are unconformably overlain by Permian and younger sedimentary rocks. The Permian rocks at the west edge of the Ayn Qunay quadrangle consist mainly of a granitic intrusive complex of batholithic dimensions. Parts of the eastern edge of the granitic complex are exposed just west of the overlying Khuff Formation of Permian age, where biotite-hornblende granite of the complex intrudes chlorite-sericite schist of the Precambrian Bi'r Khountina Group. The biotite-hornblende granite of the complex also intrudes plutons of diorite, gabbro, and pyroxenite and is itself intruded by granite porphyry, thereby indicating some difference in age between the granitic rocks in the complex. A sequence of metamorphosed volcanic rocks composed mainly of andesite, rhyolite, and kindred rocks, and called the Halaban Group, is older than the Bi'r Khountina Group. Relations between the Halaban and a gray hornblende-biotite granite gneiss are uncertain, but the gneiss may be older than the Halaban. The few observed contacts disclosed parallel foliation in the two units, but the foliation may have been imposed after the Halaban was deposited on the granite gneiss. Two major left-lateral faults extend west-northwest across the Precambrian rocks but are not in the Permian rocks. These faults parallel to the Najd fault zone found farther south. Seemingly they correlate in time with early movements on the Najd fault zone, but not with the latest. Saprolitic material-of variable thickness is present on the upper surface of the Precambrian rocks beneath the Khuff Formation at many places. Where the Khuff Formation has been removed by erosion, the saprolite is also stripped away. The weathering probably took place in pre-Khuff time. No ancient mines or prospects

  11. The tectonic evolution of the Irtysh tectonic belt: New zircon U-Pb ages of arc-related and collisional granitoids in the Kalaxiangar tectonic belt, NW China

    NASA Astrophysics Data System (ADS)

    Hong, Tao; Klemd, Reiner; Gao, Jun; Xiang, Peng; Xu, Xing-Wang; You, Jun; Wang, Xin-Shui; Wu, Chu; Li, Hao; Ke, Qiang

    2017-02-01

    Precise geochronological constraints of the Irtysh tectonic belt situated between the Saur Island Arc and the Altay Terrane are crucial to a better understanding of the tectonic evolution of the Central Asian Orogenic Belt (CAOB). Recently, we discovered repeatedly deformed arc-related and collisional granitoids in the Kalaxiangar tectonic belt (KTB), which is located in the eastern part of the Irtysh tectonic belt. In this study, we report new whole-rock geochemical, zircon U-Pb and Hf isotopic data of the arc-related and collisional granitoids. Our data reveal that 1) arc-related granodioritic porphyries formed at ca. 382-374 Ma. Recrystallized zircon grains from a (ultra-)mylonitic granodiorite of the Laoshankou zone in the southern KTB display a U-Pb age of ca. 360 Ma; 2) syn-collisional granodioritic porphyries, which distribute along faults and parallel to the cleavage, were emplaced at ca. 367-356 Ma, with εHf(t) values varying from + 7.8 to + 14.2 and Hf model ages from 873 to 459 Ma; 3) a post-collisional A-type granodioritic porphyry, which crosscuts the NW-NNW trending schistosity of the metasedimentary country rocks at a low angle, has an age of ca. 324-320 Ma, while the εHf(t) values range from + 7.6 to + 14.4 with Hf model ages from 850 to 416 Ma; 4) post-collisional strike-slip A-type granite dykes, exposed along strike-slip faults, gave ages between 287 and 279 Ma, whereas the εHf(t) values range from + 4.9 to + 12.7 and the Hf model ages from 995 to 500 Ma; and 5) A-type biotite granite dykes, which intruded along conjugate tension joints, have ages of 274-271 Ma, and εHf(t) values from + 1.5 to + 13.2 with Hf model ages from 1196 to 454 Ma. Consequently, we propose that the collision between the Saur Island Arc and the Altay Terrane occurred in the Early Carboniferous (ca. 367-356 Ma) and the subsequent post-collisional tectonic process continued to the Late Carboniferous (ca. 324-320 Ma). It is further suggested that the Irtysh tectonic belt

  12. Tellurium, a guide to mineral deposits

    USGS Publications Warehouse

    Watterson, J.R.; Gott, G.B.; Neuerburg, G.J.; Lakin, H.W.; Cathrall, J.B.

    1977-01-01

    Te dispersion patterns are useful in exploring for different types of mineral deposits and in providing additional information about known ore deposits. The Te content of rocks is given for five mining districts in the western United States: Coeur d'Alene, Idaho; Robinson, near Ely, Nevada; Montezuma, Colorado; Crater Creek area, Colorado; Cripple Creek, Colorado. Many of the analyses were obtained by use of a new analytical method sensitive to 0.001 ppm Te. The principal ore deposits in the Coeur d'Alene district, Idaho, are Pb-Zn-Ag replacement veins in Precambrian rocks of the Belt Supergroup. Te dispersion patterns show the outlines of the original mineral belts, the effects of intrusive events, the location of ore deposits, the displacements caused by post-ore faulting, and the borders of the 780-km2 district. The disseminated porphyry Cu deposits of the Robinson mining district, Nevada, are associated with Cretaceous quartz monzonite stocks that have intruded Palaeozoic carbonate rocks. Te is present in rock samples in concentrations as high as 10,000 ppm and forms a halo around the areas containing the Cu deposits. The alteration zones in the porphyry Mo district near Montezuma, Colorado, are developed around several small Tertiary intrusions occurring along a regional shear zone. Te haloes reflect the locations of porphyry intrusives, individual deposits and their ore shoots, and the pattern and intensity of adjacent alteration. The Te content of soils over the Montezuma stock is higher than, and varies independently from, the Te content of adjacent outcrops. Soils generally contain more Te than adjacent outcropping rocks. Soil may collect gaseous Te compounds from mineral deposits. The Crater Creek area is a northwestern extension of the Summitville mining district, Colorado. Te dispersion patterns radiate out from exposed Cu-Pb-Zn veins, from an outcrop of molybdenite stockwork veins and from associated iron-stained altered rock. Te haloes intensify

  13. Late-Quaternary paleovegetation, paleoclimate and fire disturbance records from subalpine sites on Vancouver Island, British Columbia, Canada

    NASA Astrophysics Data System (ADS)

    Fitton, R. J.; Brown, K. J.; Hebda, R. J.

    2003-04-01

    Analyses of pollen, macrofossils and charcoal from subalpine lakes provide insight into past climatic changes as well as local factors affecting the sites, especially since steep precipitation and temperature gradients typify mountainous regions. Lake and bog cores collected from three sites on southern and central Vancouver Island (Porphyry and Walker lakes and Harris Lake Ridge Bog) were analysed for pollen, macrofossils and charcoal and the resulting data were used to reveal post-glacial changes in vegetation, climate and fire disturbance. The paleovegetation, paleoclimate, and fire disturbance records from Porphyry and Walker Lakes parallel those from low elevations during the post-glacial interval, suggesting that these sites responded strongly to regional forcing and were somewhat less sensitive to local forcing. Of notable interest is the upward migration of lowland taxa to these lakes during the warm dry early-Holocene. A change to cooler and moister conditions in the mid- and late-Holocene is subsequently characterised by downslope movement of species ranges and the establishment of modern subalpine communities. In contrast, Harris Lake Ridge Bog from central Vancouver Island has a more complicated history that exhibits strong local and regional influences. This site is less similar to lowland records despite a relatively similar ecotonal position as the other two sites. In the early-Holocene upslope movement of low elevation species is less obvious than at Porphyry and Walker lakes. In the mid- and late-Holocene forest composition changed around Harris Lake Ridge Bog as conditions cooled and moistened and taxa better suited to nutrient poor soils, such as Tsuga mertensiana and T. heterophylla expanded. At the same time, there is evidence to suggest that local switches between forest and heather communities were initiated by fire. Consequently, records from subalpine wetlands may provide more potential for detailed reconstruction of local in

  14. Effects Of Hydrothermal Alteration On Magnetic Properties And Magnetic Signatures - Implications For Predictive Magnetic Exploration Models

    NASA Astrophysics Data System (ADS)

    Clark, D.

    2012-12-01

    Magnetics is the most widely used geophysical method in hard rock exploration and magnetic surveys are an integral part of exploration programs for many types of mineral deposit, including porphyry Cu, intrusive-related gold, volcanic-hosted epithermal Au, IOCG, VMS, and Ni sulfide deposits. However, the magnetic signatures of ore deposits and their associated mineralized systems are extremely variable and exploration that is based simply on searching for signatures that resemble those of known deposits and systems is rarely successful. Predictive magnetic exploration models are based upon well-established geological models, combined with magnetic property measurements and geological information from well-studied deposits, and guided by magnetic petrological understanding of the processes that create, destroy and modify magnetic minerals in rocks. These models are designed to guide exploration by predicting magnetic signatures that are appropriate to specific geological settings, taking into account factors such as tectonic province; protolith composition; post-formation tilting/faulting/ burial/ exhumation and partial erosion; and metamorphism. Patterns of zoned hydrothermal alteration are important indicators of potentially mineralized systems and, if properly interpreted, can provided vectors to ore. Magnetic signatures associated with these patterns at a range of scales can provide valuable information on prospectivity and can guide drilling, provided they are correctly interpreted in geological terms. This presentation reviews effects of the important types of hydrothermal alteration on magnetic properties within mineralized systems, with particular reference to porphyry copper and IOCG deposits. For example, an unmodified gold-rich porphyry copper system, emplaced into mafic-intermediate volcanic host rocks (such as Bajo de la Alumbrera, Argentina) exhibits an inner potassic zone that is strongly mineralized and magnetite-rich, which is surrounded by an outer

  15. Geologic setting and characteristic of mineral deposits in the central Wasatch Mountains, Utah

    USGS Publications Warehouse

    John, David A.

    1997-01-01

    Base- and precious-metal deposits in the central Wasatch Mountains southeast of Salt Lake City were mined for more than 100 years beginning in 1868. Deposits present in the Park City, Little Cottonwood, and Big Cottonwood mining districts include Ag-Pb-Zn ± Cu ± Au replacement and veins, a low-grade porphyry Cu-Au deposit, Cu-bearing skarns, a quartz monzonite-type (low F) porphyry Mo deposit, and high sulfidation (quartz-alunite) Au deposits. Most production came from polymetallic replacement and vein deposits in the Park City mining district, which has a recorded production of more than 1.4 million oz Au , 253 million oz Ag, 2.7 billion lbs Pb, 1.5 billion lbs Zn, and 129 million lbs Cu from 1872 to 1978. Production in the Little and Big Cottonwood districts, mostly from Pb-Ag replacement deposits, was much smaller. Most mineral deposits in the central Wasatch Mountains are genetically related to the Wasatch igneous belt, a series of high-K calc-alkaline stocks and cogenetic volcanic rocks that formed about 41(?) to 30 Ma. The mineral deposits mostly formed near the end of magmatic activity between about 36 to 31.4 Ma. A subeconomic porphyry Mo deposit in the Little Cottonwood stock is notably younger having formed about 26 to 23.5 Ma. The intrusive rocks were emplaced mostly along the westward extension of the west-trending Uinta arch during a period of NW-SE-directed extension, and much of the mineralization in the Park City district controlled by ENE-striking normal faults. About 15 degrees of eastward tilting of the central Wasatch Mountains during Late Cenozoic Basin and Range extension has resulted in progressively deeper levels of exposure from <1 km on the east to about 11 km on the west and in profound variations in the types of minerals deposits exposed in different parts of the range. Most deposits formed at paleodepths ≤5 km, and the most productive deposits in the Park City district formed at depths of 1 to 2 km. The prophyry Mo deposit in the

  16. Selective copper diffusion into quartz-hosted vapor inclusions: Evidence from other host minerals, driving forces, and consequences for Cu-Au ore formation

    NASA Astrophysics Data System (ADS)

    Seo, Jung Hun; Heinrich, Christoph A.

    2013-07-01

    Recent experimental studies have raised concerns that Cu concentrations in quartz-hosted fluid inclusions from magmatic-hydrothermal ore deposits do not represent pristine concentrations in the trapped fluids, but are modified by post-entrapment diffusional exchange through the host quartz. New microanalyses of fluid inclusions hosted in topaz show significantly lower Cu concentrations in vapor inclusions, compared to otherwise identical inclusions hosted by coexisting quartz, whereas coeval brine (hypersaline liquid) inclusions are very similar independent of host mineral in one sample. Sulfur is present as a major component in all vapor inclusions, as in most porphyry-related vapor inclusions, and Cu never exceeds S, but commonly matches the S content at a molar ratio of Cu:S ⩽ 2 in vapor inclusions hosted by quartz. Univalent ions with a radius smaller than ˜1 Å are known to diffuse rapidly through the channels of the quartz structure, parallel to its crystallographic c axis. Since only Cu concentrations differ between topaz- and quartz-hosted inclusions, we hypothesize that Cu+ and H+ re-equilibrate by diffusional ion exchange through these channels, while all other element concentrations remain essentially unchanged. A thermodynamic model considering charge-balanced Cu+H+ exchange and diffusive H2 re-equilibration of an initially Cu-poor but S-rich vapor inclusion with a typical rock-buffered fluid environment outside the host crystal demonstrates a strong chemical driving force for Cu+ to migrate from the surrounding rock into the fluid inclusion during cooling of the system. The driving force for Cu diffusion, against the gradient in total Cu concentration, is the abundant H+ liberated inside the inclusion by dissociation of HCl and particularly by the precipitation of CuFeS2 by reaction with the initially trapped H2S and/or SO2. Gold is not only a much larger ion, but is subject to an opposing driving force, suggesting that high concentrations of this

  17. Geochronology and petrogenesis of Miocene granitic intrusions related to the Zhibula Cu skarn deposit in the Gangdese belt, southern Tibet

    NASA Astrophysics Data System (ADS)

    Xu, Jing; Zheng, You-ye; Sun, Xiang; Shen, Ya-hui

    2016-04-01

    The Zhibula Cu skarn deposit (19.5 Mt ore @ 1.64%), near the Qulong porphyry Cu-Mo deposit, is located in the Gangdese porphyry copper belt in southern Tibet. The deposit is a typical metasomatic skarn that is related to the interaction of magmatic-hydrothermal fluids and calcareous host rocks. Stratiform skarn orebodies are mainly distributed in the contact between tuff and marble in the lower part of the Jurassic Yeba Formation. Endoskarn zonations for an outward trend are observed in the granodiorite, which grade from a fresh granodiorite to a weakly chlorite-altered granodiorite, a green diopside-bearing granodiorite, and a dark red-brown garnet-bearing granodiorite. The Zhibula granodiorite and monzogranite have similar secondary ion mass spectrometry (SIMS) zircon U-Pb ages of 16.9 ± 0.3 Ma and 17.0 ± 0.2 Ma, respectively. They exhibit different fractional crystallization from granodiorite (SiO2 = 64.8-69.3 wt.%) to monzogranite (SiO2 = 72.3-76.8 wt.%). Both the granodiorite and monzogranite are characterized by high Al2O3 (12.6-16.7 wt.%) and K2O (1.5-5.5 wt.%) contents, high Sr/Y (35-151) and La/Yb (19-48) ratios, and variable MgO (0.16-3.91) and Mg# (31-61) values. They display features of enrichment in large ion lithophile elements (LILEs, e.g., Rb, Ba, Sr, and K), depletion in high field strength elements (HFSEs, e.g., Nb, Ta, Ti, and P), and moderate negative Eu anomalies (δEu = 0.58-0.98). They show restricted in situ zircon Hf isotopic compositions (+6.7 to +8.8; only one sample is +4.5) and consistent δ18O values (+6.0‰ to +6.6‰). The geochemical data indicated that the Miocene Zhibula granitic intrusions formed by the magma that were characterized by high Sr/Y ratios and were derived from the partial melting of the thickened juvenile lower crust, which may have been metasomatized by the slab melts during subduction of the Neo-Tethyan oceanic crust and were induced by the convective removal of the thickened lithosphere. In addition, the

  18. Genesis of the Bangbule Pb-Zn-Cu polymetallic deposit in Tibet, western China: Evidence from zircon U-Pb geochronology and S-Pb isotopes

    NASA Astrophysics Data System (ADS)

    Kan, Tian; Zheng, Youye; Gao, Shunbao

    2016-04-01

    The Banbule Pb-Zn-Cu skarn deposit is located in the Longger-Gongbujiangda volcanic magma arc in the Gangdese-Nyainqentanglha Plate. It is the only lead-zinc polymetallic deposit discovered in the westernmost Nyainqentanglha metallogenic belt. The measured and indicated resources include 0.9 Mt of Pb+Zn (4.77% Pb and 4.74% Zn, respectively), 6499 t of Cu, and 178 t of Ag (18.75g/t Ag). The orebodies mainly occur as lenses, veins and irregular shapes in the contact zone between the quartz-porphyry and limestone of the Upper Permian Xiala Formation, or in the boundaries between limestone and sandstone. Pb-Zn-Cu mineralization in the Banbule deposit is closely associated with skarns. The ore minerals are dominated by galena, sphalerite, chalcopyrite, bornite, and magnetite, with subordinate pyrite, malachite, and azurite. The gangue minerals are mainly garnet, actinolite, diopside, quartz, and calcite. The ore-related quartz-porphyry displays LA-ICP-MS zircon U-Pb age of 77.31±0.74 Ma. The δ34S values of sulfides define a narrow range of -0.8 to 4.7‰ indicating a magmatic source for the ore-forming materials. Lead isotopic systematics yield 206Pb/204Pb of 18.698 to 18.752, 207Pb/204Pb of 15.696 to 15.760, and 208Pb/204Pb of 39.097 to 39.320. The data points are constrained around the growth curves of upper crust and orogenic belt according to the tectonic discrimination diagrams. The calculated Δβ - Δγ values plot within the magmatic field according to the discrimination diagram of Zhu et al. (1995). The S-Pb isotopic data suggest that Bangbule is a typical skarn deposit, and the Pb-Zn-Cu mineralization is genetically related to the quartz-porphyry in the mining district. The discovery of the Bangbule deposit indicates that there is metallogenic potential in the westernmost Nyainqentanglha belt, which is of great importance for the exploration work in this area.

  19. Spatial database for a global assessment of undiscovered copper resources: Chapter Z in Global mineral resource assessment

    USGS Publications Warehouse

    Dicken, Connie L.; Dunlap, Pamela; Parks, Heather L.; Hammarstrom, Jane M.; Zientek, Michael L.; Zientek, Michael L.; Hammarstrom, Jane M.; Johnson, Kathleen M.

    2016-07-13

    As part of the first-ever U.S. Geological Survey global assessment of undiscovered copper resources, data common to several regional spatial databases published by the U.S. Geological Survey, including one report from Finland and one from Greenland, were standardized, updated, and compiled into a global copper resource database. This integrated collection of spatial databases provides location, geologic and mineral resource data, and source references for deposits, significant prospects, and areas permissive for undiscovered deposits of both porphyry copper and sediment-hosted copper. The copper resource database allows for efficient modeling on a global scale in a geographic information system (GIS) and is provided in an Esri ArcGIS file geodatabase format.

  20. Mapping Phyllic and Argillic-Altered Rocks in Southeastern Afghanistan using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Data

    USGS Publications Warehouse

    Mars, John L.; Rowan, Lawrence C.

    2007-01-01

    Introduction: ASTER data and logical operators were successfully used to map phyllic and argillic-altered rocks in the southeastern part of Afghanistan. Hyperion data were used to correct ASTER band 5 and ASTER data were georegistered to orthorectified Landsat TM data. Logical operator algorithms produced argillic and phyllic byte ASTER images that were converted to vector data and overlain on ASTER and Landsat TM images. Alteration and fault patterns indicated that two areas, the Argandab igneous complex, and the Katawaz basin may contain potential polymetallic vein and porphyry copper deposits. ASTER alteration mapping in the Chagai Hills indicates less extensive phyllic and argillic-altered rocks than mapped in the Argandab igneous complex and the Katawaz basin and patterns of alteration are inconclusive to predict potential deposit types.

  1. Performance evaluation and geologic utility of LANDSAT 4 TM and MSS scanners

    NASA Technical Reports Server (NTRS)

    Paley, H. N.

    1983-01-01

    Experiments using artificial targets (polyethylene sheets) to help calibrate and evaluate atmospheric effects as well as the radiometric precision and spatial characteristics of the NS-001 and TM sensor systems were attempted and show the technical feasibility of using plastic targets for such studies, although weather precluded successful TM data acquisition. Tapes for six LANDSAT 4 TM scenes were acquired and data processing began. Computer enhanced TM simulator and LANDSAT 4 TM data were compared for a porphyry copper deposit in Southern Arizona. Preliminary analyses performed on two TM scenes acquired in the CCT-PT format, show the TM data appear to contain a marked increase in geologically useful information; however, a number of instrumental processing artifacts may well limit the ability of the geologist to fully extract this information.

  2. Nature, diversity of deposit types and metallogenic relations of South China

    USGS Publications Warehouse

    Zaw, K.; Peters, S.G.; Cromie, P.; Burrett, C.; Hou, Z.

    2007-01-01

    the 'Northern Golden Triangle' of China. These deposits are mostly epigenetic hydrothermal micron-disseminated gold deposits with associated As, Hg, Sb + Tl mineralisation similar to Carlin-type deposits in USA. The important deposits in the Southern Golden Triangle are Jinfeng (Lannigou), Zimudang, Getang, Yata and Banqi in Guizhou Province, and the Jinya and Gaolong deposits in Guangxi District. The most important deposits in the Northern Golden Triangle are the Dongbeizhai and Qiaoqiaoshang deposits. Many porphyry-related polymetallic copper-lead-zinc and gold skarn deposits occur in South China. These deposits are related to Indosinian (Triassic) and Yanshanian (Jurassic to Cretaceous) magmatism associated with collision of the South China and North China Cratons and westward subduction of the Palaeo-Pacific Plate. Most of these deposits are distributed along the Lower to Middle Yangtze River metallogenic belt. The most significant deposits are Tonglushan, Jilongshan, Fengshandong, Shitouzui and Jiguanzui. Au-(Ag-Mo)-rich porphyry-related Cu-Fe skarn deposits are also present (Chengmenshan and Wushan in Jiangxi Province and Xinqiao, Mashan-Tianmashan, Shizishan and Huangshilaoshan in Anhui Province). The South China fold belt extending from Fujian to Zhejiang Provinces is characterised by well-developed Yanshanian intrusive to subvolcanic rocks associated with porphyry to epithermal type mineralisation and mesothermal vein deposits. The largest porphyry copper deposit in China, Dexing, occurs in Jiangxi Province and is hosted by Yanshanian granodiorite. The high-sulphidation epithermal system occurs at the Zijinshan district in Fujian Province and epithermal to mesothermal vein-type deposits are also found in the Zhejiang Province (e.g., Zhilingtou). Part of Shandong Province is located at the northern margin of the South China Craton and the province has unique world class granite-hosted orogenic gold deposits. Occurrences of Pt-Pd-Ni-Cu-Co are found in Permian

  3. International Symposium on Remote Sensing of Environment, Third Thematic Conference: Remote Sensing for Exploration Geology, Colorado Springs, CO, April 16-19, 1984, Proceedings. Volumes 1 and 2

    SciTech Connect

    Not Available

    1985-01-01

    A photogeologic and remote sensing model of porphyry type mineral sytems is considered along with a Landsat application to development of a tectonic model for hydrocarbon exploration of Devonian shales in west-central Virginia, remote sensing and the funnel philosophy, Landsat-based tectonic and metallogenic synthesis of the southwest United States, and an evolving paradigm for computer vision. Attention is given to the neotectonics of the Tibetan plateau deduced from Landsat MSS image interpretation, remote sensing in northern Arizona, the use of an airborne laser system for vegetation inventories and geobotanical prospecting, an evaluation of Thematic Mapper data for hydrocarbon exploration in low-relief basins, and an evaluation of the information content of high spectral resolution imagery. Other topics explored are related to a major source of new radar data for exploration research, the accuracy of geologic maps produced from Landsat data, and an approach for the geometric rectification of radar imagery.

  4. Impacts on water quality and biota from natural acid rock drainage in Colorado's Lake Creek watershed

    USGS Publications Warehouse

    Bird, D.A.; Sares, Matthew A.; Policky, Greg A.; Schmidt, Travis S.; Church, Stanley E.

    2006-01-01

    Colorado's Lake Creek watershed hosts natural acid rock drainage that significantly impacts surface water, streambed sediment, and aquatic life. The source of the ARD is a group of iron-rich springs that emerge from intensely hydrothermally altered, unexploited, low-grade porphyry copper mineralization in the Grizzly Peak Caldera. Source water chemistry includes pH of 2.5 and dissolved metal concentrations of up to 277 mg/L aluminum, 498 mg/L iron, and 10 mg/L copper. From the hydrothermally altered area downstream for 27 kilometers to Twin Lakes Reservoir, metal concentrations in streambed sediment are elevated and the watershed experiences locally severe adverse impacts to aquatic life due to the acidic, metal-laden water. The water and sediment quality of Twin Lakes Reservoir is sufficiently improved that the reservoir supports a trout fishery, and remnants of upstream ARD are negligible.

  5. Epigenetic lead, zinc, silver, antimony, tin, and gold veins in Boulder Basin, Blaine and Custer counties, Idaho; potential for economic tin mineralization

    USGS Publications Warehouse

    Ratchford, Michael E.

    2002-01-01

    Boulder Basin is in a northwest-trending belt of allochthonous Paleozoic rocks in the Boulder Mountains of central Idaho. Regional Tertiary extension resulted in widespread normal faulting and coeval emplacement of shallow-level intrusions and extrusive rocks of the Challis Volcanic Group. Epigenetic lead-zinc-silver-antimony-tin-gold vein deposits formed during Tertiary extension and are hosted within Paleozoic strata. The major orebodies are in the lower plate of the Boulder Basin thrust fault, in massive quartzite of the Middle Pennsylvanian to Lower Permian Wood River Formation. Anomalous concentrations of tin are present in the base-metal mineral assemblage of the Boulder Basin ore deposits. The tin-bearing veins in Boulder Basin are strikingly similar to Bolivian tin deposits. The deposit model for Bolivian tin deposits identifies buried tin porphyry below the tin-bearing vein system.

  6. Deterioration Types of Stones Used in Suleymaniye Mosque (Istanbul, Turkey)

    NASA Astrophysics Data System (ADS)

    Alptekin Bilen, Candan; Erisis, Sinem; Er, Selman; Yilmaz, Murat; Angi, Serkan; Tugrul, Atiye

    2016-10-01

    Suleymaniye Mosque located in the historic peninsula of Istanbul, is one of the most important monument of classical Ottoman Architecture. Different types of natural stones having varied lithological characteristics were used in the mosque. Chemical composition, mineralogical, petrographic characteristics and external conditions such as atmospheric effects, earthquake and human impacts have deteriorated these stones over time. The aim of this study is to investigate different natural stones and their deterioration types used in Suleymaniye Mosque. According to the results obtained, generally different types of granites, marbles, limestones, pudding stones, porphyry, serpentinite were used in Suleymaniye Mosque. Detachment, material loss, biological colonization, discoloration and deposits have been determined as a deterioration types on these stones.

  7. Fluid evolution in a volcanic-hosted epithermal carbonate-base metal-gold vein system: Alto de la Blenda, Farallón Negro, Argentina

    NASA Astrophysics Data System (ADS)

    Márquez-Zavalía, M. Florencia; Heinrich, Christoph A.

    2016-10-01

    Alto de la Blenda is a ˜6.6-Ma intermediate-sulphidation epithermal vein system in the Farallón Negro Volcanic Complex, which also hosts the 7.1-Ma porphyry-Cu-Au deposit of Bajo de la Alumbrera. The epithermal vein system is characterised by a large extent and continuity (2 km × 400 m open to depth × 6 m maximum width) and an average gold grade of ˜8 g/t. The vein is best developed within an intrusion of a fine-grained equigranular monzonite, interpreted as the central conduit of a stratovolcano whose extrusive activity ended prior to porphyry-Cu-Au emplacement at Bajo de la Alumbrera, which is in turn cut by minor epithermal veins. The Alto de la Blenda vein consists predominantly of variably Mn-rich carbonates and quartz, with a few percent of pyrite, sphalerite, galena and other sulphide and sulphosalt minerals. Four phases of vein opening, hydrothermal mineralisation and repeated brecciation can be correlated between different vein segments. Stages 2 and 3 contain the greatest fraction of sulphide and gold. They are separated by the emplacement of a polymictic breccia containing clasts of quartz feldspar porphyry as well as basement rocks. Fluid inclusions in quartz related to stages 2 to 4 are liquid rich with 2-4 wt% NaCl(eq). They homogenise between 160 and 300 °C, with very consistent values within each assemblage. Vapour inclusions are practically absent in the epithermal vein. Quartz fragments in the polymictic breccia contain inclusions of intermediate to vapour-like density and similar low salinity (˜3 wt% NaCl(eq)), besides rare brine inclusions containing halite. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses of epithermal inclusions indicate high concentrations of K, Fe, As, Sb, Cs, and Pb that significantly vary within and through subsequent vein stages. Careful consideration of detection limits for individual inclusions shows high gold concentrations of ˜0.5 to 3 ppm dissolved in the ore fluid, which

  8. Petrology, geochemistry and U-Pb geochronology of magmatic rocks from the high-sulfidation epithermal Au-Cu Chelopech deposit, Srednogorie zone, Bulgaria

    NASA Astrophysics Data System (ADS)

    Chambefort, Isabelle; Moritz, Robert; von Quadt, Albrecht

    2007-10-01

    Chelopech area and the about 92-Ma-old Elatsite porphyry-Cu deposit, suggest two different magma sources in the Chelopech-Elatsite magmatic area. Magmatic rocks associated with the Elatsite porphyry-Cu deposit and the dacitic dome-like body north of Chelopech are characterized by zircons with ɛHfT90 values of ˜5, which suggest an important input of mantle-derived magma. Some zircons display lower ɛHfT90 values, as low as -6, and correlate with increasing 206Pb/238U ages up to about 350 Ma, suggesting assimilation of basement rocks during magmatism. In contrast, zircon grains in andesitic rocks from Chelopech are characterized by homogeneous 176Hf/177Hf isotope ratios with ɛHfT90 values of ˜1 and suggest a homogeneous mixed crust-mantle magma source. We conclude that the Elatsite porphyry-Cu and the Chelopech high-sulfidation epithermal deposits were formed within a very short time span and could be partly contemporaneous. However, they are related to two distinct upper crustal magmatic reservoirs, and they cannot be considered as a genetically paired porphyry-Cu and high-sulfidation epithermal related to a single magmatic-hydrothermal system centered on the same intrusion.

  9. Petrography and mineral chemistry of the composite Deboullie Pluton, northern Maine, USA: implications for the genesis of Cu-Mo mineralization

    USGS Publications Warehouse

    Loferski, P.J.; Ayuso, R.A.

    1995-01-01

    Biotite and apatite mineral chemistry, particularly halogen abundances and ratios, are used to investigate the relation of the two contrasting parts of the Deboullie composite pluton (syenite-granodiorite) located in northern Maine. Biotite mineral chemistry helps to classify the weakly developed porphyry-style mineralization (Cu-Mo) associated with syenitic rocks of the Deboullie pluton. Biotite and apatite occur within the matrix of the rocks and within small multiphase inclusions hosted by clinopyroxene. The inclusions are interpreted to be crystallized melt inclusions rather than solid inclusions, that were trapped by clinopyroxene during growth. The multiphase inclusions consist of K-feldspar + quartz + biotite + apatite + magnetite. On a regional scale, biotite compositions from granitic plutons in Maine do not vary in a systematic manner. -from Authors

  10. BLUE RANGE WILDERNESS, ARIZONA AND NEW MEXICO.

    USGS Publications Warehouse

    Ratte, James C.; Raabe, R.G.

    1984-01-01

    A mineral survey of the area was completed and it was determined that a probable resource potential for molybdenum, copper, and silver is present in volcanic rocks of middle Tertiary age in the southern and southwestern parts of the area. There is also a likelihood for the occurrence of base-metal resources (including porphyry copper deposits) of Laramide age beneath the middle Tertiary volcanic rocks that cover the area, but data are insufficient to assess the resource potential. Improved techniques for interpreting geophysical data collected over complex volcanic terranes should be applied in an effort to identify Laramide intrusives beneath the middle Tertiary rocks. Additional geologic studies of the major faults and volcanic centers might enhance mineral-deposit target definition in the middle Tertiary rocks.

  11. WEAVER BALLY ROADLESS AREA, CALIFORNIA.

    USGS Publications Warehouse

    Blake, M.C.; Peters, T.J.

    1984-01-01

    The Weaver Bally Roadless Area includes approximately 22 sq mi in the Shasta-Trinity National Forest, Trinity County, California. A mineral survey indicates that an area of less than 1 sq mi in the northern part of the Weaver Bally Roadless Area has a substantiated mineral-resource potential for gold and silver; a much larger area has a probable mineral-resource potential for the same elements. The geologic terrane precludes the occurrence of fossil fuel resources and there is little promise for the occurrence of additional metallic, energy, or nonmetallic resources in the roadless area. Detailed studies, including further geochemical sampling and drilling could be done in the region of the Globe mines. In addition, the outcrops of dacite porphyry dikes and sills and associated hydrothermal alteration should be mapped in detail.

  12. Refined Proterozoic evolution of the Gawler Craton, South Australia, through U-Pb zircon geochronology

    USGS Publications Warehouse

    Fanning, C.M.; Flint, R.B.; Parker, A.J.; Ludwig, K. R.; Blissett, A.H.

    1988-01-01

    Through the application of both conventional U-Pb zircon analyses and small-sample U-Pb isotopic analyses, the nature and timing of tectonic events leading to the formation of the Gawler Craton have been defined more precisely. Constraints on deposition of Early Proterozoic iron formation-bearing sediments have been narrowed down to the period 1960-1847 Ma. Deformed acid volcanics, including the economically important Moonta Porphyry, have zircon ages of ??? 1790 and 1740 Ma. The voluminous acid Gawler Range Volcanics and correlatives to the east were erupted over a short interval at 1592 ?? 2 Ma, and were intruded by anorogenic granites at ??? 1575 Ma. Small-sample zircon analyses proved to be an extremely valuable adjunct to conventional analyses, generally yielding more-concordant data which forced a curved discordia through an upper intercept slightly younger than from a conventional straight-line discordia. ?? 1988.

  13. Mercury in soil gas and air--A potential tool in mineral exploration

    USGS Publications Warehouse

    McCarthy, Joseph Howard; Vaughn, W.W.; Learned, R.E.; Meuschke, J.L.

    1969-01-01

    The mercury content in soil gas and in the atmosphere was measured in several mining districts to test the possibility that the mercury content in the atmosphere is higher over ore deposits than over barren ground. At Cortez, Nev., the distribution of anorhalous amounts of mercury in the air collected at ground level (soil gas) correlates well with the distribution of gold-bearing rocks that are covered by as much as 100 feet of gravel. The mercury content in the atmosphere collected at an altitude of 200 feet by an aircraft was 20 times background over a mercury posit and 10 times background over two porphyry copper deposits. Measurement of mercury in soil gas and air may prove to be a valuable exploration tool.

  14. GOAT ROCKS WILDERNESS AND ADJACENT ROADLESS AREAS, WASHINGTON.

    USGS Publications Warehouse

    Church, S.E.; Close, T.J.

    1984-01-01

    The Goat Rocks Wilderness and adjacent roadless areas are a rugged, highly forested, scenic area located on the crest of the Cascade Range in south-central Washington. Several mineral claims have been staked in the area. Mineral surveys were conducted. Geochemical, geophysical, and geologic investigations indicate that three areas have probable mineral-resource potential for base metals in porphyry-type deposits. Available data are not adequate to permit definition of the potential for oil and gas. There is little likelihood for the occurrence of other kinds of energy resources in the area. Evaluation of resource potential in the three areas identified as having probable mineral-resource potential could be improved by more detailed geochemical studies and geologic mapping.

  15. Ore-bearing hydrothermal metasomatic processes in the Elbrus volcanic center, the northern Caucasus, Russia

    NASA Astrophysics Data System (ADS)

    Gurbanov, A. G.; Bogatikov, O. A.; Dokuchaev, A. Ya.; Gazeev, V. M.; Abramov, S. S.; Groznova, E. O.; Shevchenko, A. V.

    2008-06-01

    -ralstonite, and fluorite-identified in these metasomatic rocks for the first time. By analogy with porphyry Cu-Mo deposits in Chile and the United States, the ore mineralization of the KOMS may be classified by composition and textural and structural attributes as a supraore level of porphyry copper genetic type. The volcanic rocks of the KOMS and the EVC as a whole are enriched in Ag, Mo, Zn, As, Sb, Se, and Ba. Judging from the scale of argillic alteration and taking into account the data on porphyry Cu-Mo ore-magmatic systems of the Greater Caucasus, veined Pb-Zn ore mineralization may be expected in the propylitic zone at a depth down to 1000 m from the present-day erosion level of the KOMS. Stringer-disseminated Au-Ag, Cu, and Cu-Mo ore mineralization of the upper part of the porphyry ore-magmatic system related to subvolcanic dacitic intrusions may be localized somewhat deeper.

  16. Paleohydrologic evolution and geochemical dynamics of cumulative supergene metal enrichment at La Escondida, Atacama Desert, northern Chile

    USGS Publications Warehouse

    Alpers, C.N.; Brimhall, G.H.

    1989-01-01

    Quantitative limonite mapping within the leached capping of the porphyry copper deposit at La Escondida, Chile, permits reconstruction of the paleohydrologic and chemical evolution of a well-developed supergene ore-forming system. The mineralogy, textures, and relative abundance of supergene limonite minerals (hematite, goethite, and jarosite) are used to reconstruct the former ratio of pyrite to chalcocite and the preoxidation copper grade based on empirical limonite sulfide correlations. Evidence for cumulative downward enrichment in vertical profiles through leached capping allows quantitative analysis of chemical mass balance in dynamic supergene systems. Slopes of linear regressions for profiles of reconstructed enriched copper grades vs. depth indicate lateral fluxes into or out of a given vertical profile. -from Authors

  17. Summary of space imagery studies in Utah and Nevada

    NASA Technical Reports Server (NTRS)

    Jensen, M. L. (Principal Investigator)

    1975-01-01

    The author has identified the following significant results. An enhanced enlargement of a S190B color image at a scale of 1/19,200 of the Bingham porphyry copper deposit has compared a geological map of the area with the space imagery map as fair for the intrusion boundaries and total lack of quality for mapping the sediments. Hydrothermal alteration is only slightly evident on space imagery at Bingham, but in the Tintic mining district and the volcanic piles of the Keg and Thomas ranges, Utah, hydrothermal alteration is readily mapped on color enlargements of S190B. Several sites of calderas were recognized and new ones located on space imagery. One of the tools developed is a mercury soil-gas analyzer that is becoming significant as an aid in locating hidden mineralized zones which were suggested from space imagery. In addition, this tool is a prime aid in locating and better delineating geothermal sites.

  18. The metal content of molybdenum-mineralizing fluids

    NASA Astrophysics Data System (ADS)

    Lerchbaumer, L.; Audétat, A.

    2012-04-01

    Molybdenum can be found in porphyry-type systems as well as in hydrothermal veins and breccias associated with granite systems. Up to now our knowledge on the metal content of fluids forming molybdenum ore deposits has been very limited. The only data available so far are from the porphyry Mo deposit at Questa, New Mexico, and from the Cave Peak porphyry Mo-Nb deposit in Texas. We have studied early, intermediate-density fluid inclusions in quartz crystals from miarolitic cavities in the Drammen and Glitrevann granites (Norway) and the Treasure Mountain Dome (Colorado/USA) to obtain more information about the bulk composition of magmatic-hydrothermal fluids exsolved from these plutons. The Treasure Mountain Dome contains weak Mo mineralization and is an apophysis of the Alma Batholith that produced also the famous Climax and Henderson porphyry Mo deposits; the Glitrevann granite hosts a sub-economic Mo stockwork, and the Drammen Granite contains numerous vein-type Mo mineralizations. As a preliminary result, based on analyses of fluid inclusions using optical microscopy, microthermometry, Raman spectroscopy, and LA-ICP-MS we conclude that the primordial fluid of the Drammen granite was of high acidity and carried certain amounts of metals at conditions of 650°C and 1.3-1.5 kbar. The total elemental budget is: 3 wt% Na, 1.8 wt% K, 0.5 wt% S, 0.4 wt% Fe, 0.3 wt% Cu, 0.2 wt% Mn, 40 ppm Mo, 800 ppm Zn, 600 ppm Rb, 300 ppm Cs, 180 ppm Pb, 150 ppm As, 40 ppm W, 15 ppm Bi, and minor amounts of Ag, Sn, and Ce. Striking is the fact, that all the metal concentrations show little variability except the one of Cu. In view of recent studies (Lerchbaumer & Audétat, 2011) showing that the Cu-values in quartz-hosted fluid inclusions are not always representative of the primary fluid and in fact can be too high, we want to check if this could be the case for the Cu-values measured in the samples from Norway and Colorado. The alteration of the original Cu-concentrations stems from

  19. The Paleozoic tectonic evolution and metallogenesis of the northern margin of East Junggar, Central Asia Orogenic Belt: Geochronological and geochemical constraints from igneous rocks of the Qiaoxiahala Fe-Cu deposit

    NASA Astrophysics Data System (ADS)

    Liang, Pei; Chen, Huayong; Hollings, Pete; Xiao, Bing; Wu, Chao; Bao, Zhiwei; Cai, Keda

    2016-11-01

    The East Junggar terrane (NW China) is an important constituent of the Central Asian Orogenic Belt (CAOB). From the Devonian to Permian, regional magmatism evolved from mainly calc-alkaline (I-type) to alkaline (A-type). The Qiaoxiahala Fe-Cu deposit, located in the Late Paleozoic Dulate island arc (northern margin of the East Junggar), is hosted in the volcanic rocks of the Middle Devonian Beitashan Formation. Two magmatic stages were identified in the deposit, the Qiaoxiahala diorite porphyry (380 ± 4.0 Ma) and a younger aplite (331 ± 3.1 Ma). The (high-K) calc-alkaline Beitashan Formation basaltic rocks are characterized by LILE and LREE enrichments and HFSE depletions, pointing to a subduction-related affinity. The high Mg# (42-75), elevated Ce/Th and Ba/Th, depleted Nb, positive εNd(t) (6.6), low (87Sr/86Sr)i (0.7037) and MORB-like Pb isotope characters all suggest an origin involving partial melting of a MORB-like depleted mantle wedge (metasomatized by slab-derived fluids) with little evidence of crustal contamination. The calc-alkaline (I-type) diorite porphyry, characterized by LILE and LREE enrichments and HFSE depletions, may have formed from fractional crystallization of the basaltic rocks, with its parental magma derived from the same depleted mantle wedge. The negative εHf(t) (-8.26), Hf model age (TDMC) of 1406 Ma and the presence of inherited zircons (ca. 470 and 506 Ma) indicate that the diorite has assimilated older crustal material. The alkaline, metaluminous (A-type) aplite is characterized by HFSE enrichment and depletions in Sr, P and Ti, distinct from the basaltic rocks and diorite porphyry at Qiaoxiahala. The low Mg# (35-38), positive Zr and Hf, positive εHf(t) (4.77-9.75) and εNd(t) (6.85-6.86) and low T2DM (538-520 Ma) suggest a juvenile lower crustal source due to partial melting of basaltic lower crust as a result of underplating of mantle-derived melts and accompanied by magma mixing. The tectonic evolution of the Paleozoic East

  20. A geochemical survey using heavy mineral concentrates in the Mount Belknap caldera vicinity, Utah

    USGS Publications Warehouse

    Tucker, R.E.; Miller, W. Roger; Motooka, J.M.

    1982-01-01

    Geochemical surveys of the rocks, heavy-mineral concentrates, and surface and spring waters in the vicinity of the Mount Belknap caldera, Tushar Mountains, west-central Utah, were conducted during the summers of 1978 and 1979. Anomalous concentrations of mostly lithophile elements, particularly niobium, beryllium, lead, yttrium, tin, zinc, manganese, and molybdenum in the magnetic and nonmagnetic fraction of heavy-mineral concentrates derived from stream sediment suggest that late stage, highly differentiated felsic rocks were involved in the eruptive history of the Mount Belknap caldera. Q-mode factor analysis was used to characterize the geochemical assemblages within the survey area, and the areal distribution of high-factor scores associated with mineralization indicates favorable target areas for future exploration. The results of these studies indicate that porphyry-type molybdenum and possible associated vein-type uranium mineralized deposits may exist in or near the Mount Belknap caldera.

  1. DOMELAND WILDERNESS, DOMELAND ADDITION, AND WOODPECKER ROADLESS AREAS, CALIFORNIA.

    USGS Publications Warehouse

    Bergquist, Joel R.; Spear, James M.

    1984-01-01

    A mineral survey of the Domeland Wilderness and the contiguous Domeland Addition and Woodpecker Roadless Areas delineated areas of substantiated and probable mineral-resource potential. The areas of substantiated resource potential are in the Woodpecker Roadless Area where alluvial gravel in Rockhouse Basin and on Upper Trout Creek contains small, irregular, low-grade deposits of placer gold. There is a probable resource potential for very small deposits of uranium in fractures in granitic rocks west of the South Fork of the Kern River in the Domeland Wilderness. Geochemical data indicate a probable potential for a porphyry-molybdenum deposit at the southern end of the Domeland Wilderness, and for very small deposits of tungsten, copper-lead-zinc, tin, silver, and molybdenum at several places in the wilderness and roadless areas. The geologic terrane precludes the occurrence of organic fuel resources.

  2. GEOCHEMISTRY OF MAJUBA HILL, NEVADA.

    USGS Publications Warehouse

    Wenrich, Karen J.; Mascarenas, Joseph F.; Silberman, Miles L.

    1984-01-01

    Majuba Hill is the erosional remnant of a mineralized volcanic complex of rhyolite porphyry stocks, dikes, sills and irregular masses of breccia intruded into Triassic(? ) argillites. Majuba Hill is best known for its Cu and Sn ore; in addition, it was mineralized with other metals of possible economic significance, most notably, Mo, Ag, and U. Although this is an intrusive complex with no evidence of any extrusive phases, it was intruded sufficiently near the surface to develop a porphyritic texture. Intense sericitic and argillic alteration affected all stages of intrusion. Fresh rocks were not available for K-Ar analyses. Several samples of feldspars and sericite from altered zones yielded K-Ar ages for the alteration of 24. 7 to 25. 5 m. y. The tight clustering of ages suggests that all stages of the complex were altered within less than 1 m. y.

  3. Rock Magnetic and Paleointensity Study of Eastern California's ~83 Ma Golden Bear and Coso Dikes

    NASA Astrophysics Data System (ADS)

    Feldman, M.; Raub, T. D.

    2009-12-01

    Extraordinary intermediate-composition (Kspar +/- quartz andesite porphyry) dikes are coincident with the end of Sierra Nevada magmatism and crop out on both the east and the west sides of Owens Valley, but offset dextrally by >60 km. If this offset represents ancient (possibly Cretaceous) strike-slip partitioning of Pacific-North America plate boundary strain, then at least one of the south- and east-sited Coso dikes might be expected to be paleomagnetically "identical" to its presumed paleo-contiguous, north- and west-sited Golden Bear partner. Accompanying a directional study by Pluhar and colleagues at CSU-Fresno, we are characterizing magnetic mineralogy, fabric, and thermal lability of Coso dikes and the Golden Bear dike. We are also applying the pTRM difference multi-specimen paleointensity technique to these samples, testing for across-Owens Valley correlation.

  4. Comparison of the 1984 and 1985 AIS data over the Singatse Range (Yerington), Nevada

    NASA Technical Reports Server (NTRS)

    Lyon, R. J. P.

    1986-01-01

    The Singatse Range is composed of a series of 53 types of volcanic, plutonic, metamorphic, and sedimentary rocks. In addition the Jurassic plutonic rocks are also of economic interest for their copper mineralization which is contained in a porphyry dike swarm. The 1984 and 1985 flight results from the Airborne Imaging Spectrometer (AIS) instrument flown in the NASA/JPL C-130 aircraft are contrasted and compared. The 1984 data are less noisy than the 1985, in which many sets of vertical stripings from bad detectors can be seen. Significantly however, enough of the hydrothermal alteration patterns can be seen in each line at the mutual crossing points that one can say that the specific targets were detected in both year's flights. The spectra of both years are corrupted by the second-order effect from the grating, but 0-H bond absorption at essentially correct wavelengths for sericite and/or kaolinite can be seen.

  5. International Symposium on Remote Sensing of Environment, Third Thematic Conference: Remote Sensing for Exploration Geology, Colorado Springs, CO, April 16-19, 1984, Proceedings. Volumes 1 & 2

    NASA Technical Reports Server (NTRS)

    1985-01-01

    A photogeologic and remote sensing model of porphyry type mineral sytems is considered along with a Landsat application to development of a tectonic model for hydrocarbon exploration of Devonian shales in west-central Virginia, remote sensing and the funnel philosophy, Landsat-based tectonic and metallogenic synthesis of the southwest United States, and an evolving paradigm for computer vision. Attention is given to the neotectonics of the Tibetan plateau deduced from Landsat MSS image interpretation, remote sensing in northern Arizona, the use of an airborne laser system for vegetation inventories and geobotanical prospecting, an evaluation of Thematic Mapper data for hydrocarbon exploration in low-relief basins, and an evaluation of the information content of high spectral resolution imagery. Other topics explored are related to a major source of new radar data for exploration research, the accuracy of geologic maps produced from Landsat data, and an approach for the geometric rectification of radar imagery.

  6. Volcanology and mineral deposits

    USGS Publications Warehouse

    Lipman, P.W.

    1990-01-01

    In contrast, old volcanic regions, which host many of the world's major hydrothermal-vein, porphyry, and massive-sulfide ore deposits, have been studied mainly by economic geologists, regional stratigraphers, and structural geologists who have limited familiarity with the complexities of volcanic processes. Such "dead" volcanoes, ranging in age from a few million million years (tertiary) to a few billion years (Precambrian), are commonly incompletely and discontinuously preserved due to rapid erosion of originally high-standing volcanic edifices. They can be difficult to date reliably, especially in terms of the time scales of individual volcanic events, and are variably hydrothermally altered-impeding high-resolution petrologic and geochemical studies. Many volcanologists, geochemists, and geophysicists who work on active volcanoes accordingly have been reluctant to become involved in studies of such less tractable rocks. 

  7. Reverse telescoping in distal skarns at Campiglia Marittima (Italy)

    NASA Astrophysics Data System (ADS)

    Vezzoni, Simone; Dini, Andrea; Rocchi, Sergio

    2014-05-01

    Skarn deposits commonly results from the metasomatic alteration of a rock, usually carbonate-rich, by infiltration of hydrothermal fluids. Most carbonate-hosted skarn deposits show a direct spatial relationship with magmatic intrusions and an intimate relationship with porphyry copper deposits. Their primary mineralogical and geochemical features indicate metasomatism by high-temperature magmatic fluids. Conversely, many distal Pb-Zn-Ag skarns pose an important challenge because there is no apparent association with magmatic intrusions and external, meteoric and/or basinal fluids should become increasingly dominant with increasing distance from the igneous source. Nevertheless recent investigation of distal skarn deposits indicates that ore-forming fluids match the composition of proximal magmatic fluids in granitoid-related mineral deposits. Besides that metal producer (Pb, Zn, Ag, Cu, Fe, W, Sn), skarn deposits can be key to understanding fluid dynamics at the periphery of magmatic-hydrothermal systems, unraveling pathways to hidden ore deposits (e.g porphyry copper). In this scenario, research on distal skarns opens new perspectives for deep mineral exploration and/or modeling of intrusion centered geothermal systems, because they should represent the outer limit of the hydrothermal system dominated by magmatic aqueous fluids. Here we present exceptional evidences from a distal Pb-Zn-Ag skarn deposit in Campiglia Marittima, Italy, where the magma, after having released the metasomatic fluids, fled up chasing its own fluid stream and invading large pockets of the newly formed skarn bodies at shallower level. Detailed underground mapping and petrologic data indicate that, after the formation of a typical distal Pb-Zn-Ag skarn, the intrusion of the parent magma produced prograde reactions in the skarn silicates, mobilization of the Pb-Zn-Ag sulfides and precipitation of a new Cu-Fe sulfide assemblage. This is a very unusual case of reverse telescoping during which

  8. Mineral Deposit Data for Epigenetic Base- and Precious-metal and Uranium-thorium Deposits in South-central and Southwestern Montana and Southern and Central Idaho

    USGS Publications Warehouse

    Klein, T.L.

    2004-01-01

    Metal deposits spatially associated with the Cretaceous Boulder and Idaho batholiths of southwestern Montana and southern and central Idaho have been exploited since the early 1860s. Au was first discovered in placer deposits; exploitation of vein deposits in bedrock soon followed. In 1865, high-grade Ag vein deposits were discovered and remained economically important until the 1890s. Early high-grade deposits of Au, Ag and Pb were found in the weathered portions of the veins systems. As mining progressed to deeper levels, Ag and Pb grades diminished. Exploration for and development of these vein deposits in this area have continued until the present. A majority of these base- and precious-metal vein deposits are classified as polymetallic veins (PMV) and polymetallic carbonate-replacement (PMR) deposits in this compilation. Porphyry Cu and Mo, epithermal (Au, Ag, Hg and Sb), base- and precious-metal and W skarn, W vein, and U and Th vein deposits are also common in this area. The world-class Butte Cu porphyry and the Butte high-sulfidation Cu vein deposits are in this study area. PMV and PMR deposits are the most numerous in the region and constitute about 85% of the deposit records compiled. Several types of syngenetic/diagenetic sulfide mineral deposits in rocks of the Belt Supergroup or their equivalents are common in the region and they have been the source of a substantial metal production over the last century. These syngenetic deposits and their metamorphosed/structurally remobilized equivalents were not included in this database; therefore, deposits in the Idaho portion of the Coeur d'Alene district and the Idaho Cobalt belt, for example, have not been included because many of them are believed to be of this type.

  9. Groundwater resources of the East Mountain area, Bernalillo, Sandoval, Santa Fe, and Torrance Counties, New Mexico, 2005

    USGS Publications Warehouse

    Bartolino, James R.; Anderholm, Scott K.; Myers, Nathan C.

    2010-01-01

    The groundwater resources of about 400 square miles of the East Mountain area of Bernalillo, Sandoval, Santa Fe, and Torrance Counties in central New Mexico were evaluated by using groundwater levels and water-quality analyses, and updated geologic mapping. Substantial development in the study area (population increased by 11,000, or 50 percent, from 1990 through 2000) has raised concerns about the effects of growth on water resources. The last comprehensive examination of the water resources of the study area was done in 1980-this study examines a slightly different area and incorporates data collected in the intervening 25 years. The East Mountain area is geologically and hydrologically complex-in addition to the geologic units, such features as the Sandia Mountains, Tijeras and Gutierrez Faults, Tijeras syncline and anticline, and the Estancia Basin affect the movement, availability, and water quality of the groundwater system. The stratigraphic units were separated into eight hydrostratigraphic units, each having distinct hydraulic and chemical properties. Overall, the major hydrostratigraphic units are the Madera-Sandia and Abo-Yeso; however, other units are the primary source of supply in some areas. Despite the eight previously defined hydrostratigraphic units, water-level contours were drawn on the generalized regional potentiometric map assuming all hydrostratigraphic units are connected and function as a single aquifer system. Groundwater originates as infiltration of precipitation in upland areas (Sandia, Manzano, and Manzanita Mountains, and the Ortiz Porphyry Belt) and moves downgradient into the Tijeras Graben, Tijeras Canyon, San Pedro synclinorium, and the Hagan, Estancia, and Espanola Basins. The study area was divided into eight groundwater areas defined on the basis of geologic, hydrologic, and geochemical information-Tijeras Canyon, Cedar Crest, Tijeras Graben, Estancia Basin, San Pedro Creek, Ortiz Porphyry Belt, Hagan Basin, and Upper Sandia

  10. Molybdenite in the Montezuma District of central Colorado

    USGS Publications Warehouse

    Neuerburg, George J.; Botinelly, Theodore; Watterson, John R.

    1974-01-01

    The Montezuma mining district, in the Colorado mineral belt, is defined by an assemblage of porphyry, ore, and altered rocks that originated in the venting of a Tertiary batholith through weak structures in Precambrian rocks. The ore consists of silver-lead-zinc veins clustered on the propylitic fringe of a geometrically complex system of altered rocks, which is centered on the intersection of the Oligocene Montezuma stock with the Montezuma shear zone of Precambrian ancestry. Alteration chemistry conforms to the standard porphyry-metal model but is developed around several small intrusives strung out along the shear zone and is expressed as a mottled pattern, rather than as the usual thick concentric zones centered on one large plug. The distribution of trace amounts of molybdenite is consistent with the postulate of molybdenite deposits in the district, but the mottled alteration pattern may signify small and scattered, possibly very deep, deposits. Disseminated molybdenite is essentially coextensive with altered rock and increases slightly in quantity toward the inner alteration zones. Two groups of molybdenite veins, associated with phyllic and potassic alteration, represent possible diffuse halos of molybdenite deposits. One group of veins resembles the Climax and Henderson deposits but was seen only in a small and isolated area of outcrops. The second group of molybdenite veins is in a bismuth-rich part of the Montezuma stock and underlies an area of bismuth veins; this group records the passage of contact metasomatic ore fluids. Another bismuth-rich area is in the southeast corner of the stock in a region of bismuth veins and may indicate a third group of molybdenite veins.

  11. Geology and lithogeochemistry of the Ren gold prospect, Elko County, Nevada - the role of rock sampling in exploration for deep Carlin-type deposits

    USGS Publications Warehouse

    Albino, G.V.

    1994-01-01

    The Ren gold prospect, Elko County, Nevada, is in the northern part of the Carlin trend, two kilometers northwest of the recently-discovered, high-grade Purple Vein deposit. The Ren area is underlain mainly by Paleozoic sedimentary rocks, consisting of limestone, calcareous siltstone, and mudstone of the eastern (carbonate) assemblage, overlain in thrust contact by chert, quartzite, and mudstone of the western (siliceous) assemblage. Cretaceous(?) granodiorite porphyry and hornblende porphyry dikes have intruded the sedimentary rocks along north-striking faults. Three stages of mineralization include a pre- or syntectonic base metal-barite assemblage, a middle stage of Ag- and Sb-rich jasperoid, and a late Au-rich stage responsible for the potentially economic mineralization at the prospect. The latter two stages of alteration and mineralization were focused along steep east-dipping faults and dikes, and the nearly flat-lying contact between lower massive limestone and laminated calcareous siltstone. Mineralization is present between 380 and 500 m below the surface. Alteration includes decalcification and weak silicification in siltstone, and formation of massive jasperoid in the upper part of the limestone unit. Alteration of dikes is mainly sericite-quartz-pyrite, with late pyrite-quartz-kaolinite. The element suite characteristic of Au-stage mineralization includes Au, As, and Hg with minor Ag and Hg; Ag and Sb are most enriched in the earlier jasperoid event. Haloes of As and Hg extend at least 80 m above the Au mineralization, but no anomalies are present at the surface. Gold anomalies are more widespread, and extend to shallower depths, but are less coherent. ?? 1994.

  12. Geology and geochemistry of the Mammoth breccia pipe, Copper Creek mining district, southeastern Arizona: Evidence for a magmatic-hydrothermal origin

    USGS Publications Warehouse

    Anderson, E.D.; Atkinson, W.W.; Marsh, T.; Iriondo, A.

    2009-01-01

    The Copper Creek mining district, southeastern Arizona, contains more than 500 mineralized breccia pipes, buried porphyry-style, copper-bearing stockworks, and distal lead-silver veins. The breccia pipes are hosted by the Copper Creek Granodiorite and the Glory Hole volcanic rocks. The unexposed Mammoth breccia pipe, solely recognized by drilling, has a vertical extent of 800 m and a maximum width of 180 m. The pipe consists of angular clasts of granodiorite cemented by quartz, chalcopyrite, bornite, anhydrite, and calcite. Biotite 40Ar/ 39Ar dates suggest a minimum age of 61.5??0.7 Ma for the host Copper Creek Granodiorite and 40Ar/39Ar dates on hydrothermal sericite indicate an age of 61.0??0.5 Ma for copper mineralization. Fluid inclusion studies suggest that a supercritical fluid with a salinity of approximately 10 wt.% NaCl equiv. condensed to a dilute aqueous vapor (1-2.8 wt.% NaCl equiv.) and a hypersaline brine (33.4-35.1 wt.% NaCl equiv.). Minimum trapping temperatures are 375??C and trapping depths are estimated at 2 km. Sulfur isotope fractionation of cogenetic anhydrite and chalcopyrite yields a temperature of mineralization of 469??25??C. Calculated oxygen and hydrogen isotope values for fluids in equilibrium with quartz and sericite range from 10.2??? to 13.4??? and -60??? to -39???, respectively, suggesting that the mineralizing fluid was dominantly magmatic. Evidence from the stable isotope and fluid inclusion analyses suggests that the fluids responsible for Cu mineralization within the Mammoth breccia pipe exsolved from a gray porphyry phase found at the base of the breccia pipe. ?? Springer-Verlag 2008.

  13. Au-Ag polymetallic mineralization within tectonically weak zones along the southwestern edge of the Colorado Plateau

    SciTech Connect

    Wenrich, K.J.; Silberman, M.L. )

    1993-04-01

    The Music Mountain mining district lies at the base of the Grand Wash Cliffs, a major fault-line scarp along the Grand Wash fault, which marks the SW margin of the Colorado Plateau. Nearly vertical Au-Ag polymetallic quartz veins parallel, and are in contact with, altered diabase and granite porphyry dikes that cut Proterozoic granite, schist, and gneiss. The gold-bearing veins range in thickness from an inch to several feet and contain significant amounts of sulfide minerals. Diabase dikes and quartz veins in the district and to the north consistently strike N42[degree]W to N57[degree]W, which is one of the most prevalent fracture orientation throughout NW Arizona. In the Gold Basin-Lost Basin districts to the north, the Au occurs in such pegmatite-quartz veins that strike NE. Thirty miles east along Diamond Creek, quartz veins and diabase dikes strike N45[degree]E and are associated with Au and Ag anomalies in stream-sediments and panned concentrates. To the west major Au-Ag polymetallic quartz veins of the Wallapai mining district show consistent strikes from N30[degree] to 60[degree]W. K-Ar ages of hydrothermal alterations of 4 NW oriented diabase dikes that have quartz veins along them, range from 935 [+-] 35 to 755 [+-] 21 Ma. Sericite from altered granite porphyry, adjacent to a mineralized vein, gave a K-Ar age of 72 [+-]2 Ma. All geochemical sites (within a 1,000 mi[sup 2] area) determined to be anomalous in Au lie within 2 mi of either the Grand Wash or Hurricane faults. The Hurricane and Grand Wash faults, major Precambrian fault zones that were reactivated in the Phanerozoic, appear to be good exploration targets for Au-rich quartz veins associated with pegmatite or diabase dikes, many of which may be buried beneath the thick alluvium of Hualapai Valley.

  14. Timing of multiple hydrothermal events in the iron oxide-copper-gold deposits of the Southern Copper Belt, Carajás Province, Brazil

    NASA Astrophysics Data System (ADS)

    Moreto, Carolina P. N.; Monteiro, Lena V. S.; Xavier, Roberto P.; Creaser, Robert A.; DuFrane, S. Andrew; Melo, Gustavo H. C.; Delinardo da Silva, Marco A.; Tassinari, Colombo C. G.; Sato, Kei

    2015-06-01

    The Southern Copper Belt, Carajás Province, Brazil, hosts several iron oxide-copper-gold (IOCG) deposits, including Sossego, Cristalino, Alvo 118, Bacuri, Bacaba, Castanha, and Visconde. Mapping and U-Pb sensitive high-resolution ion microprobe (SHRIMP) IIe zircon geochronology allowed the characterization of the host rocks, situated within regional WNW-ESE shear zones. They encompass Mesoarchean (3.08-2.85 Ga) TTG orthogneiss, granites, and remains of greenstone belts, Neoarchean (ca. 2.74 Ga) granite, shallow-emplaced porphyries, and granophyric granite coeval with gabbro, and Paleoproterozoic (1.88 Ga) porphyry dykes. Extensive hydrothermal zones include albite-scapolite, biotite-scapolite-tourmaline-magnetite alteration, and proximal potassium feldspar, chlorite-epidote and chalcopyrite formation. U-Pb laser ablation multicollector inductively coupled mass spectrometry (LA-MC-ICP-MS) analysis of ore-related monazite and Re-Os NTIMS analysis of molybdenite suggest multiple Neoarchean (2.76 and 2.72-2.68 Ga) and Paleoproterozoic (2.06 Ga) hydrothermal events at the Bacaba and Bacuri deposits. These results, combined with available geochronological data from the literature, indicate recurrence of hydrothermal systems in the Southern Copper Belt, including 1.90-1.88-Ga ore formation in the Sossego-Curral ore bodies and the Alvo 118 deposit. Although early hydrothermal evolution at 2.76 Ga points to fluid migration coeval with the Carajás Basin formation, the main episode of IOCG genesis (2.72-2.68 Ga) is related to basin inversion coupled with Neoarchean (ca. 2.7 Ga) felsic magmatism. The data suggest that the IOCG deposits in the Southern Copper Belt and those in the Northern Copper Belt (2.57-Ga Salobo and Igarapé Bahia-Alemão deposits) do not share a common metallogenic evolution. Therefore, the association of all IOCG deposits of the Carajás Province with a single extensive hydrothermal system is precluded.

  15. Quartz-sericite and argillic alterations at the Peschanka Cu-Mo-Au deposit, Chukchi Peninsula, Russia

    NASA Astrophysics Data System (ADS)

    Marushchenko, L. I.; Baksheev, I. A.; Nagornaya, E. V.; Chitalin, A. F.; Nikolaev, Yu. N.; Kal'ko, I. A.; Prokofiev, V. Yu.

    2015-05-01

    The porphyry Peschanka copper-molybdenum-gold deposit and the Nakhodka ore field located in the Baimka ore trend on the western Chukchi Peninsula are spatially related to monzonitic rocks of the Early Cretaceous Egdykgych Complex. Two types of quartz-sericite metasomatic rocks (QSR) have been identified at both the deposits and the ore field: (I) chlorite-quartz-muscovite rock with bornite and chalcopyrite (porphyry type) and (II) tourmaline-quartz-carbonate-muscovite ± phengite rock accompanied by veins with base-metal mineralization (subepithermal or transitional type), as well as carbonate-quartz-illite rock (argillic alteration) accompanied by veins with precious metal mineralization (epithermal type). The QSR I chlorite evolves from chamosite to clinochlore, which is caused by increasing H2S activity in mineralizing fluid and precipitation of sulfide minerals. The QSR I clinochlore is significantly depleted in silica as compared with that from the rocks affected by argillic alteration. The chemical composition of muscovite from both quartz-sericite alterations is similar. The QSR II carbonates evolve from calcite through dolomite to siderite, which results from the increasing activity of CO2 followed by the decreasing activity of H2S in mineralizing fluid. The Mn content in dolomite is similar to that in beresite (quartz-muscovite-carbonate-pyrite metasomatic rock) of the intrusion-related gold deposits. Illite from argillic alteration is depleted in Al as compared with that of postvolcanic epithermal Au-Ag deposits. However, carbonates from the discussed argillic alteration rhodochrosite and Mn-rich dolomite are similar to those from quartz-illite rock at postvolcanic epithermal Au-Ag deposits.

  16. Ancient mines of the Farah Garan area, southwestern Saudi Arabia

    USGS Publications Warehouse

    Smith, C.W.; Blank, H. Richard

    1979-01-01

    Ancient miners, in quest of oxidized copper minerals, gold, silver, and possibly zinc, mined gossans to approximately 20 m depth in an area 1.1 by 0.5 km in extent at Farah Garan. The gossans, derived from sulfides, are ordinarily found at contacts between marble lenses and metavolcanic-metasedimentary rocks, but in the southern part of the mined area, gossans are also within marbles. The gossans are generally lensoidal and discontinuous along strike. The same type of metallization, in similar rocks, was found at the Hemair ancient workings, about 3 km southeast. Both deposits are thought to be of epigenetic origin, and ore deposition was controlled by shearing along marble contacts. Drilling is recommended at Farah Garan. Al Ashyab is 4 km south of Farah Garan, and similar rocks and structures extend through both areas but there are no ancient workings at Al Ashyab. The dominant geologic feature in the area is a high, narrow, light-colored ridge consisting of intensely silicified quartz porphyry. Pyritized metavolcanic rocks envelope the silicified rock, and geochemical sampling revealed weakly anomalous, erratically spaced concentrations of copper and zinc within these rocks. No further work is recommended for the area. Quartz-filled fractures containing gold were mapped at Al Asharfat, Lejourah, and other locations where ancient miners worked the veins. The gold-bearing quartz veins are narrow and have short strike lengths, and potential tonnages are thought to be small. The veins are in younger, more massive rocks than the enclosing metamorphic rocks and are thought to be younger than the adjacent sulfide deposits. No further work is recommended. Pyritized zones and associated sparse copper oxides extend intermittently about 6 km south of Hemair in metasedimentary rocks of the Jiddah group. Similar zones, associated quartz vein swarms, and minor magnetite and gold are found in mafic metavolcanic rocks adjacent to the contact with quartz porphyry about 1 km west

  17. The Papsy's Hope autunite prospect, Marysvale District, Piute County, Utah

    USGS Publications Warehouse

    Kaiser, Edward P.

    1950-01-01

    The Papsy's Hope autunite prospect is in the eastern part of the Marysvale district, Piute County, Utah, about 1 1/2 miles northeast of the mines now operating. It is developed by two shallow cuts and a short incline shaft. One cut exposes a zone of fractures, sparse quartz veins, and scattered autunite. Most if the autunite is exposed within a north-south distance of 17 feet. The trend of the zone is not known. Samples across the autunite-bearing zone average 0.026 percent equivalent uranium. The deposit is in feldspar porphyry of the older Tertiary (Bullion Canyon) volcanics. The intrusive quartz monzonite that contains the deposits now being mined is in contact with quartz porphyry similar to the rocks exposed about 1500 feet west if the Papsy’s Hope prospect. In comparing the Papsy’s Pope prospect with the deposits now being mined, two major correlations have been observed. (1) The deposits at the Papsy’s Hope prospect and those at the Bullion Monarch and Prospector mined are immediately beneath the old erosion surface at the base if the y0ounger tertiary volcanics. The younger volcanics are still present a short distance to the nrth and south of the Papsy’s Hope perospect. (2) The deposits at the Papsy’s Hope prospect and at the Prospector mine are associated with completely silicified outcrops. These correlations may prove of value for prospecting, and further study of the m is in progress. Further prospecting would be necessary to determine the trend of the autunite-bearing zone and to expose it at greater depth. This could be done by trenching across the probable northeast-southwest trend of the zone, by drilling, and either extending the present inclines shaft, or, preferably, driving a new incline at a lower level.

  18. H2O-driven generation of picritic melts in the Middle to Late Triassic Stuhini arc of the Stikine terrane, British Columbia, Canada

    NASA Astrophysics Data System (ADS)

    Milidragovic, Dejan; Chapman, John B.; Bichlmaier, Sebastian; Canil, Dante; Zagorevski, Alex

    2016-11-01

    Basaltic to andesitic compositions predominate island arc magmatism; ultramafic magmas are rare. Ultramafic (MgO = 21-33 wt.%) tuff breccia, lapilli tuff, and ash tuff of the Middle to Upper Triassic Stuhini Group were erupted in the Stikine arc of the North American Cordillera shortly preceding an episode of prolific porphyry Cu-Mo(-Au) mineralization. The ultramafic tuff shows accumulation (20-65%) of olivine (Fo91) and minor chromite into a subalkaline picritic parental magma with MgO ∼16 wt.%. Despite the inferred high MgO content of the parental liquid, chromite phenocrysts record relatively low liquidus temperatures (<1200 °C) suggesting crystallization from relatively low temperature, hydrous melts, at oxygen fugacities one to three log units above the fayalite-magnetite-quartz (FMQ) buffer. The primary picritic magmas likely contained 5-7 wt.% H2O, inferred on the basis of olivine-liquid thermometry and thermal models for subduction zones, thus alleviating the need for catastrophic thermal perturbations in the mantle wedge. Instead, efficient release of water through slab dehydration at 2.5-3.0 GPa allows generation of picritic melts at ordinary mantle wedge temperatures through moderate degrees (F = 0.10- 0.15) of hydrous flux melting. The volatile-rich nature of the melt and the predominant extensional regime in the overlying lithosphere of Stikinia facilitated the near-adiabatic ascent of the Stuhini Group picrites. The high H2O content of the rapidly ascending picrite melt may have played a key role in transport of metals into the crust of the Stikinia and subsequent porphyry mineralization.

  19. The geology and 40Ar/ 39Ar geochronology of magmatic activity and related mineralization in the Nevados del Famatina mining district, La Rioja province, Argentina

    NASA Astrophysics Data System (ADS)

    Losada-Calderón, A. J.; McBride, S. L.; Bloom, M. S.

    1994-01-01

    The Nevados del Famatina mining district (NFMD) is located in La Rioja province, Argentina. This district contains porphyry-style mineralization (Nevados del Famatina) and high sulfidation veins (La Mejicana). The stratigraphic column in the NFMD begins with Cambrian siltstones which were metamorphosed during the Late Ordovician - Early Silurian and intruded by Late Ordovician-Silurian granitic rocks. These units were covered by Upper Paleozoic and Tertiary continental sedimentary rocks which are intercalated with and overlain by dacitic-rhyodacitic porphyritic rocks (Mogote Formation) emplaced during the Pliocene. All these units are covered by Pleistocene sediments and Quaternary alluvial and colluvial deposits. Magmatic activity and related mineralization in the NFMD have been dated by the 40Ar/ 39Ar technique. Step heating studies of orthoclase and biotite phenocrysts from the Mogote Formation in the NFMD suggest that the igneous rocks were emplaced around 5.0±0.3 Ma ago. However, plateau ages of biotite from the outer carapace of the subjacent granodioritic magma chamber and of muscovite from quartz-sericite alteration at both Nevados del Famatina and La Mejicana are around 3.8±0.2 Ma. Emplacement of the shallow stocks is separated from cooling of the outer carapace of the subjacent granodioritic magma chamber to temperatures below 350° C by a time span of approximately 1 Ma. During this interval, a convective hydrothermal system was established proximal to the granodioritic magma chamber, which resulted in porphyry molybdenumcoppergold mineralization adjacent to the igneous rocks and more distal high sulfidation veins located in fault zones.

  20. Mapping known and potential mineral occurrences and host rocks in the Bonnifield Mining District using minimal cloud- and snow-cover ASTER data: Chapter E in Recent U.S. Geological Survey studies in the Tintina Gold Province, Alaska, United States, and Yukon, Canada--results of a 5-year project

    USGS Publications Warehouse

    Hubbard, Bernard E.; Dusel-Bacon, Cynthia; Rowan, Lawrence C.; Eppinger, Robert G.; Gough, Larry P.; Day, Warren C.

    2007-01-01

    On July 8, 2003, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor acquired satellite imagery of a 60-kilometer-wide swath covering a portion of the Bonnifield mining district within the southernmost part of the Tintina Gold Province, Alaska, under unusually favorable conditions of minimal cloud and snow cover. Although rocks from more than eight different lithotectonic terranes are exposed within the extended swath of data, we focus on volcanogenic massive sulfides (VMS) and porphyry deposits within the Yukon-Tanana terrane (YTT), the largest Mesozoic accretionary terrane exposed between the Denali fault system to the south of Fairbanks and the Tintina fault system to the north of Fairbanks. Comparison of thermal-infrared region (TIR) decorrelation stretch data to available geologic maps indicates that rocks from the YTT contain a wide range of rock types ranging in composition from mafic metavolcanic rocks to felsic rock types such as metarhyolites, pelitic schists, and quartzites. The nine-band ASTER visible-near-infrared region--short-wave infrared region (VNIR-SWIR) reflectance data and spectral matched-filter processing were used to map hydrothermal alteration patterns associated with VMS and porphyry deposit types. In particular, smectite, kaolinite, opaline silica, jarosite and (or) other ferric iron minerals defined narrow (less than 250-meter diameter) zonal patterns around Red Mountain and other potential VMS targets. Using ASTER we identified some of the known mineral deposits in the region, as well as mineralogically similar targets that may represent potential undiscovered deposits. Some known deposits were not identified and may have been obscured by vegetation or snow cover or were too small to be resolved.

  1. The geology and ore deposits of Upper Mayflower Gulch, Summit County, Colorado

    USGS Publications Warehouse

    Randall, John Alexander

    1958-01-01

    Upper Mayflower Gulch is on the highly glaciated western side of the Tenmile Range near Kokomo in central Colorado. Somewhat less than $500,000 in silver and gold has been produced from the area since the first mining in the 1880' s. In the mapped area high grade regional metamorphism has produced two varieties of gneiss and a granulite. Total thickness of the rocks is about 5,000 feet. Relict bedding is preserved in compositional banding which strikes north to N. 20 ? E. and dips 70 ? to 80 ? southeast. No significant folding was observed. Normal faulting has occurred since the Precambrian; two major sets of faults are recognizable: (1) a set striking N. 70 ? to 85 ? E. and dipping 75?-85 ? NW; and (2) a set striking N. 70?-50 ? W. and dipping 50?-60 ? SW. Tabular bodies of pegmatite and retrogressively metamorphosed schist along many faults indicate Precambrian movement. The Mayflower fault, a 90 to 300 foot wide zone of siltification and shattered rock, strikes about N. 40 ? W. It extends the entire length of the gulch and appears to form the northern terminus for the northeast trending Mosquito Fault. The Mayflower fault shows repeated movement since the Precambrian, totaling about 3,000 feet of apparent dip slip and 640 feet of apparent strike slip. Faulting during the Tertiary includes both additional movement along Precambrian faults and development of shears trending N. to N. 20 ? E. The shears served as channels for the intrusion of two varieties of quartz latite porphyry dikes. Specular hematite and base-metal sulfide mineralization followed intrusion of the porphyry dikes; the minerals were deposited in open fault zones by high temperature solutions in a low pressure environment. The principal metallic minerals in order of deposition are: hematite, pyrite, chalcopyrite, sphalerite, galena, and rarer argentite. The major mines are the Gold Crest, Payrock, Nova Scotia Boy, and Bird's Nest.

  2. Age constraints on the hydrothermal history of the Prominent Hill iron oxide copper-gold deposit, South Australia

    NASA Astrophysics Data System (ADS)

    Bowden, Bryan; Fraser, Geoff; Davidson, Garry J.; Meffre, Sebastien; Skirrow, Roger; Bull, Stuart; Thompson, Jay

    2016-12-01

    The Mesoproterozoic Prominent Hill iron-oxide copper-gold deposit lies on the fault-bound southern edge of the Mt Woods Domain, Gawler Craton, South Australia. Chalcocite-bornite-chalcopyrite ores occur in a hematitic breccia complex that has similarities to the Olympic Dam deposit, but were emplaced in a shallow water clastic-carbonate package overlying a thick andesite-dacite pile. The sequence has been overturned against the major, steep, east-west, Hangingwall Fault, beyond which lies the clastic to potentially evaporitic Blue Duck Metasediments. Immediately north of the deposit, these metasediments have been intruded by dacite porphyry and granitoid and metasomatised to form magnetite-calc-silicate skarn ± pyrite-chalcopyrite. The hematitic breccia complex is strongly sericitised and silicified, has a large sericite ± chlorite halo, and was intruded by dykes during and after sericitisation. This paper evaluates the age of sericite formation in the mineralised breccias and provides constraints on the timing of granitoid intrusion and skarn formation in the terrain adjoining the mineralisation. The breccia complex contains fragments of granitoid and porphyry that are found here to be part of the Gawler Range Volcanics/Hiltaba Suite magmatic event at 1600-1570 Ma. This indicates that some breccia formation post-dated granitoid intrusion. Monazite and apatite in Fe-P-REE-albite metasomatised granitoid, paragenetically linked with magnetite skarn formation north of the Hangingwall Fault, grew soon after granitoid intrusion, although the apatite experienced U-Pb-LREE loss during later fluid-mineral interaction; this accounts for its calculated age of 1544 ± 39 Ma. To the south of the fault, within the breccia, 40Ar-39Ar ages yield a minimum age of sericitisation (+Cu+Fe+REE) of dykes and volcanics of ˜1575 Ma, firmly placing Prominent Hill ore formation as part of the Gawler Range Volcanics/Hiltaba Suite magmatic event within the Olympic Cu-Au province of the

  3. Rejuvenation of shallow-crustal silicic magma bodies at Augustine and Hayes volcanoes, Alaska

    NASA Astrophysics Data System (ADS)

    Coombs, M. L.; Vazquez, J. A.; Hayden, L. A.; Calvert, A. T.; Lidzbarski, M. I.; Andersen, N. L.; Till, C. B.

    2015-12-01

    Rejuvenation of crystal-rich magma bodies leading to eruption can occur on a variety of scales and in varied tectonic settings. Two examples from the Aleutian arc highlight 1) segregation of silicic melt from an intermediate mush, and 2) "defrosting" of a shallowly emplaced intrusion. Augustine Volcano erupted a late Pleistocene rhyolite pumice fall that we link through zircon geochronology to cumulate dioritic blocks, ripped from Augustine's shallow magmatic plumbing system and ejected during the 2006 eruption. Unpolished zircon rims from the rhyolite yield a U-Th age of ~25 ka, and interiors yield a dominant age population of ~26 ka. Zircons from diorites have interior ages and compositions indistinguishable from those of the rhyolite. The diorites, rhyolite, and early Holocene dacites define whole-rock linear unmixing trends consistent with melt (rhyolite) extraction from a mush (dacites), leaving behind a cumulate residue (diorites). A volatile-rich basalt erupted just prior to the rhyolite likely facilitated melt extraction from the mush. The rhyolitic Hayes River ignimbrite, erupted from Hayes volcano, contains dense porphyry blocks that match pumices in composition and phenocryst content and are samples of a shallow intrusion. Autocrystic monazite accommodated up to several weight % Th and significantly affected the U-Th ratio of the magma during differentiation. An isochron for early melt and low-U monazites yields an age of ~67 ka, whereas one for late melt and high-U monazites yields ~42 ka. This younger age is indistinguishable from the laser single crystal Ar-Ar age for sanidine of 41±2 ka (1 sigma). We interpret the apparent ~25 k.y. crystallization interval to represent the assembly and differentiation timescale associated with the Hayes magma body. Sharp reverse zoning in sanidine from pumice (but not porphyry) records a thermal pulse not seen in the more slowly reacting phases, suggesting that a rejuvenation event occurred just prior to eruption.

  4. Dyke swarms and their role in the genesis of world-class gold deposits: Insights from the Jiaodong peninsula, China

    NASA Astrophysics Data System (ADS)

    Li, Lin; Li, Sheng-Rong; Santosh, M.; Li, Qing; Gu, Yue; Lü, Wen-Jie; Zhang, Hua-Feng; Shen, Jun-Feng; Zhao, Guo-Chun

    2016-11-01

    Jiaodong peninsula, located at the southeastern margin of the North China Craton, is well known for its rich endowment of super-large gold deposits. This region is also characterized by hundreds of intermediate - mafic dykes that cluster into several dyke swarms. In this study, we present zircon U-Pb ages which show that the timing of dyke emplacement as ca. 120 Ma, which followed the crystallization of the (quartz-) diorite porphyry at ca. 130 Ma. These ages coincide with the peak ages reported for magmatism and metallogeny in the central North China Craton. The various ages (2450-2570 and 154 Ma) from the inherited zircon crystals in these rocks suggest that substantial lower to middle crustal basement rocks and Jurassic granitoids were involved during dyke emplacement. The dyke swarms, varying between alkaline and subalkaline, are compositionally low-Si low-Ti lamprophyre and low-Si high-Ti dolerite porphyry in the western of the Jiaodong peninsula, whereas those in the eastern part are composed of both high-Si low-Ti and low-Si high-Ti lamprophyres. These features imply multiple sources for the dykes from convective asthenospheric mantle to ancient enriched lithospheric mantle with magma generation at different depths involving mixture of slab-derived hydrous fluids. The source magmas of the dykes were hydrous and enriched in volatiles as well as ore components, and their evolution occurred under high oxygen fugacity conditions. The relatively rapid emplacement and cooling of the dyke systems enabled the migration of fluids into ore-controlling faults or fractures. We envisage that the dyke swarms played an important role in generating the world-class gold mineralization of Jiaodong.

  5. Cenozoic strike-slip faults in the northern Wassuk Range, Walker Lane

    SciTech Connect

    Dilles, J.H. . Geosciences Dept.)

    1993-04-01

    The N. Wassuk Ra. yields estimates of right-lateral Cenozoic strain in a portion of the northwest-trending Walker Lane, which has a total estimated right-lateral strain of 48--60 km (Ekren et al., 1984). The net right-lateral strain is < 10 km within an east-west 50 km-long segment extending from the N. Wassuk Ra. west to the Pine Nut Mts on the basis of continuous Jurassic plutonic units: Yerington batholith and quartz monzodiorite porphyry dikes. One of two dikes in the N. Wassuk Ra. may correlate easterly to Gillis Ra., suggesting [approximately]10 or 25 km right-lateral offset (Diles and R. Hardyman, unpub). In the N. Wassuk Ra. there are several ages of northwesterly striking faults. The oldest are [approximately]N45[degree]W striking, steeply dipping faults including the White Mt. and Wassuk Spur faults that step left to the northwest. Associated moderately dipping faults have tilted Oligocene tuffs to the W or SW to the SW of the fault zone, and both E and W on the NW; based on offset of the Jurassic porphyry dike and slickensides, these faults were dominantly oblique-slip normal faults with WNW-ESE slip. No lateral offsets can be directly measured across the steeply dipping faults; however, they juxtapose different Mesozoic metamorphic rocks and different thicknesses of Oligocene ignimbrites, suggesting significant lateral offset. Bingler's (1978) proposal that the White Mt. fault had left-laterally offset the White Mt. granite (WMG) from granite of Black Mountain (BMG) is unreasonable because the BMG intrudes the Wassuk Range diorite and contain biotite aplites, whereas the WMG intrudes metavolcanic rocks and contains tourmaline-muscovite aplites.

  6. Natural factors and mining activity bearings on the water quality of the Choapa basin, North Central Chile: insights on the role of mafic volcanic rocks in the buffering of the acid drainage process.

    PubMed

    Parra, Amparo; Oyarzún, Jorge; Maturana, Hugo; Kretschmer, Nicole; Meza, Francisco; Oyarzún, Ricardo

    2011-10-01

    This contribution analyzes water chemical data for the Choapa basin, North Central Chile, for the period 1980-2004. The parameters considered are As, Cu Fe, pH, EC, SO₄⁻², Cl⁻¹, and HCO[Formula: see text], from samples taken in nine monitoring stations throughout the basin. Results show rather moderate contents of As, Cu, and Fe, with the exception of the Cuncumén River and the Aucó creek, explained by the influence of the huge porphyry copper deposit of Los Pelambres and by the presence of mining operations, respectively. When compared against results obtained in previous researches at the neighboring Elqui river basin, which host the El Indio Au-Cu-As district, a much reduced grade of pollution is recognized for the Choapa basin. Considering the effect of acid rock drainage (ARD)-related Cu contents on the fine fraction of the sediments of both river basins, the differences recorded are even more striking. Although the Los Pelambres porphyry copper deposit, on the headwaters of the Choapa river basin, is between one and two orders of magnitude bigger than El Indio, stream water and sediments of the former exhibit significantly lower copper contents than those of the latter. A main factor which may explain these results is the smaller degree of H( + )-metasomatism on the host rocks of the Los Pelambres deposit, where mafic andesitic volcanic rocks presenting propylitic hydrothermal alteration are dominant. This fact contrast with the highly altered host rocks of El Indio district, where most of them have lost their potential to neutralize ARD.

  7. Double-layer structure of the crust beneath the Zhongdian arc, SW China: U-Pb geochronology and Hf isotope evidence

    NASA Astrophysics Data System (ADS)

    Cao, Kang; Xu, Ji-Feng; Chen, Jian-Lin; Huang, Xiao-Xiao; Ren, Jiang-Bo; Zhao, Xiang-Dong; Liu, Zhen-Xing

    2016-01-01

    U-Pb ages and Hf isotopes of zircons in Late Triassic and Cretaceous intrusive rocks from the Zhongdian arc, SW China, are used to decipher the tectonic, magmatic, and metallogenic processes that occurred during this period. New U-Pb dating of zircons from Late Triassic porphyries yielded ages of ca. 216 Ma and εHf(t) values of -2.1 to +6.1. Combined with previous results, the data indicate that these Late Triassic rocks were most likely derived from a juvenile mafic lower-crust with minor old crust material. However, the Cretaceous granites (∼80 Ma) have lower εHf(t) values (-7.6 to -2.4) than the Late Triassic rocks, indicating that the former originated from old crust. Based on the new data and previous studies of Mesozoic magmatic activity, a plausible model for the tectono-magmatism and metallogenesis of the Zhongdian arc is proposed. The westwards subduction of the Ganzi-Litang oceanic crust began before ∼230 Ma, resulting in the formation of a juvenile lower crust beneath the Zhongdian arc due to the underplating of mafic arc magmas during ca. 230-216 Ma. At ca. 216 Ma, break-off or slab-tearing of the west-dipping Ganzi-Litang oceanic slab led to partial melting of the juvenile lower crust, which gave rise to Cu-bearing porphyries. In the Late Cretaceous, the Zhongdian arc probably underwent post-collision extension, triggering the partial melting of the old middle-upper crustal materials and producing various granites and related Mo-Cu deposits. According to this model, the crust beneath the Zhongdian arc probably has a double-layer structure, with older crust at shallow levels and juvenile crust at deeper levels.

  8. The Effect of Coastline Changes to Local Community's Social-Economic

    NASA Astrophysics Data System (ADS)

    Hassan, M. I.; Rahmat, N. H.

    2016-09-01

    The coastal area is absolutely essential for the purposes of resident, recreation, tourism, fisheries and agriculture as a source of socio-economic development of local community. Some of the activities will affect the coastline changes. Coastline changes may occur due to two main factors include natural factors and also by the factor of human activities in coastal areas. Sea level rise, erosion and sedimentation are among the factors that can contribute to the changes in the coastline naturally, while the reclamation and development in coastal areas are factors of coastline changes due to human activities. Resident area and all activities in coastal areas will provide economic resources to the residents of coastal areas. However, coastline changes occur in the coastal areas will affect socio-economic for local community. A significant effect can be seen through destruction of infrastructure, loss of land, and destroy of crops. Batu Pahat is an area with significant changes of coastline. The changes of coastline from 1985 to 2013 can be determined by using topographical maps in 1985 and satellite images where the changes images are taken in 2011 and 2013 respectively. To identify the changes of risk areas, Coastal Vulnerability Index (CVI) is used to indicate vulnerability for coastal areas. This change indirectly affects the source of income in their agricultural cash crops such as oil palm and coconut. Their crops destroyed and reduced due to impact of changes in the coastline. Identification of risk coastal areas needs to be done in order for the society and local authorities to be prepared for coastline changes.

  9. Evaluation on the decomposability of tropical forest peat soils after conversion to an oil palm plantation.

    PubMed

    Sangok, Faustina E; Maie, Nagamitsu; Melling, Lulie; Watanabe, Akira

    2017-06-01

    To understand the variations in the decomposability of tropical peat soil following deforestation for an oil palm plantation, a field incubation experiment was conducted in Sarawak, Malaysia. Peat soils collected from three types of primary forest, namely Mixed Peat Swamp (MPS; Gonystylus-Dactylocladus-Neoscrotechinia association), Alan Batu (ABt; Shorea albida-Gonstylus-Strenonurus association), and Alan Bunga (ABg; Shorea albida association), were packed in polyvinyl chloride pipes and installed in an oil palm plantation. Carbon dioxide (CO2) and methane (CH4) fluxes from soil were monthly measured for 3years. Environmental variables including soil temperature, soil moisture content, and groundwater table were also monitored. The pH, loss on ignition, and total carbon (C) content were similar among the three soils, while total N content was larger in the MPS than in the ABg soils. Based on (13)C nuclear magnetic resonance (NMR) spectroscopy, C composition of the MPS and ABg soils was characterized by the largest proportion of C present as alkyl C and O-alkyl C, respectively. The C composition of the ABt soil was intermediate between the MPS and ABg soils. The CO2 fluxes from the three soils ranged from 78 to 625mgCm(-2)h(-1) with a negative correlation to groundwater level. The CH4 fluxes ranged from -67 to 653μgCm(-2)h(-1). Both total CO2 and CH4 fluxes were larger in the order ABg>ABt>MPS (P<0.05). Annual rate of peat decomposition as was estimated from cumulative C loss differed up to 2 times, and the rate constant in exponential decay model was 0.033y(-1) for the MPS soil and 0.066y(-1) for the ABg soil. The field incubation results of the three forest peat soils seem to reflect the difference in the labile organic matter content, represented by polysaccharides.

  10. Phenology and growth adjustments of oil palm (Elaeis guineensis) to photoperiod and climate variability

    PubMed Central

    Legros, S.; Mialet-Serra, I.; Caliman, J.-P.; Siregar, F. A.; Clément-Vidal, A.; Dingkuhn, M.

    2009-01-01

    Background and Aims Oil palm flowering and fruit production show seasonal maxima whose causes are unknown. Drought periods confound these rhythms, making it difficult to analyse or predict dynamics of production. The present work aims to analyse phenological and growth responses of adult oil palms to seasonal and inter-annual climatic variability. Methods Two oil palm genotypes planted in a replicated design at two sites in Indonesia underwent monthly observations during 22 months in 2006–2008. Measurements included growth of vegetative and reproductive organs, morphology and phenology. Drought was estimated from climatic water balance (rainfall – potential evapotranspiration) and simulated fraction of transpirable soil water. Production history of the same plants for 2001–2005 was used for inter-annual analyses. Key Results Drought was absent at the equatorial Kandista site (0°55′N) but the Batu Mulia site (3°12′S) had a dry season with variable severity. Vegetative growth and leaf appearance rate fluctuated with drought level. Yield of fruit, a function of the number of female inflorescences produced, was negatively correlated with photoperiod at Kandista. Dual annual maxima were observed supporting a recent theory of circadian control. The photoperiod-sensitive phases were estimated at 9 (or 9 + 12 × n) months before bunch maturity for a given phytomer. The main sensitive phase for drought effects was estimated at 29 months before bunch maturity, presumably associated with inflorescence sex determination. Conclusion It is assumed that seasonal peaks of flowering in oil palm are controlled even near the equator by photoperiod response within a phytomer. These patterns are confounded with drought effects that affect flowering (yield) with long time-lag. Resulting dynamics are complex, but if the present results are confirmed it will be possible to predict them with models. PMID:19748909