Sample records for quaternary alluvial deposits

  1. Modern and ancient alluvial fan deposits

    SciTech Connect

    Nilsen, T.H.

    1985-01-01

    Understanding the structure and depositional processes of alluvial fans (river outwash deposits) has a special interest for those involved with the exploration of petroleum and many minerals. This collection of facsimile reprints of significant and classical research papers sheds new light on the subject. This reference covers the stratigraphy, sedimentology, and depositional processes of modern and ancient alluvial fans. Geographical areas considered include Arctic Canada, the American Southwest, Australia, Wyoming, Norway, and Spain. It includes a state-of-the-art introduction by the editor along with commentaries on all the papers included, a master author citation index and a subject index, and a chronological listing of early studies of alluvial fans.

  2. Late Quaternary paleodrainage reconstruction of the Maros River alluvial fan

    NASA Astrophysics Data System (ADS)

    Kiss, Tímea; Sümeghy, Borbála; Sipos, György

    2014-01-01

    The surface of the extensive Maros alluvial fan is densely (0.78 km/km2) covered by paleochannels. The aim of the present study is to reconstruct the final (late Quaternary) stage of the alluvial fan development by identifying paleodrainage directions and determining morphology and pattern of the paleochannels and the age of their activity. On the surface of the alluvial fan, 18 meandering, braided, anastomosing, or misfit paleochannel zones were identified. The existence of these channels indicates that the main process of the fan development was avulsion rather than lateral channel shift, and the overbank floodplain accumulation played a minor role as the paleochannels were not buried. The oldest paleodrainages (A-C) shifted towards north from the east-west-axis of the alluvial fan, draining water to the Körös basin. The similar age (18.7 ± 2.3 ka-14.2 ± 1.4 ka) of the paleochannel zones indicates rapid avulsions or the coexistence of paleodrainages. In the northern half of the alluvial fan, the last large (D) paleodrainage change occurred 12.4 ± 2.1 ka, when the channel turned westward. A large meandering channel functioned for a period (12.4 ± 2.1 ka-9.6 ± 1.3 ka); and with the coexisting misfit channels, these channels drained a considerable amount of water (Qb = 2500 m3/s). In the next development phase (E paleodrainages), the Maros flowed north; but after a sharp bend, it turned toward the south, and it started to form the southern lobe of the alluvial fan. These channels existed between 8.5 ± 0.9 ka and 3.5 ± 0.4 ka and had a bankfull discharge of 1000-2000 m3/s. The last (F) paleodrainage of the Maros River existed for a short time (1.9 ± 0.3 ka-1.6 ± 0.3 ka) and indicated decreasing discharge (Qb = 1400 m3/s). In the final phase of the alluvial fan evolution, the present-day course of the river was developed, and its discharge decreased further (680 m3/s).

  3. Late Quaternary alluvial fans at the eastern end of the San Bernardino Mountains, Southern California

    NASA Astrophysics Data System (ADS)

    Owen, Lewis A.; Clemmens, Samuel J.; Finkel, Robert C.; Gray, Harrison

    2014-03-01

    Alluvial fans at the eastern end of the San Bernardino Mountains in Southern California provide a record of climate modulated sediment transfer and erosion, and are deformed and displaced in places by active faults. Alluvial fans within two study areas, the Mission Creek and the Whitewater River drainages, were examined using geomorphic, sedimentological, and 10Be terrestrial cosmogenic nuclide (TCN) surface exposure methods to define the timing of alluvial fan formation and erosion, and to examine the role of climatic, tectonic and autocyclic processes. These alluvial fan complexes were studied because they are amongst the best-preserved successions of alluvial fans in southern California and they are located at the mouths of two of the largest drainages, Whitewater River and Mission Creek, in the San Bernardino Mountains and traverse major faults, the Mission Creek and Banning. The alluvial fans comprise bouldery debris deposits that represent deposition dominated by flash flood and debris flow events. TCN surface exposure dating indicates that abandonment/incision of alluvial fan surfaces date to early in the Last Glacial or more likely the penultimate glacial cycle, to marine isotope stage (MIS) 4, and to the Holocene. The lack of alluvial fan ages during the latter part of the Last Glacial (MIS 2 and 3) suggests that there has been little alluvial fan lobe deposition/incision during that time. This is similar to findings for many other alluvial fans throughout the American Southwest, and supports the view that there is a strong climatic control on alluvial fan formation throughout this region. Furthermore, the oldest alluvial fan surfaces in the Mission Creek region are beheaded by the Whitewater River drainage, showing that the oldest alluvial fans in the Mission Creek region underwent significant capture by the Whitewater River drainage. This shows the autocyclic controls are also important on alluvial fan evolution in this region; but the importance of these processes to alluvial fan development in other regions of the American Southwest needs to be more fully assessed. The alluvial fans in the Mission Creek area traverse the Mission Creek fault, but are not deformed by it, which suggests that there may have been little if any movement along this fault since at least MIS 4. In contrast, alluvial fans in the Whitewater River study are displaced by active faults highlighting the influence of tectonism on alluvial fan development in this region. In addition to illustrating the importance of climatic controls on the development of alluvial fans in the American Southwest, a classic region for alluvial fan studies, this study illustrates the complex mixture of autocyclic and allocyclic factors that force alluvial fan development in tectonically active settings.

  4. Sedimentary and tectonic evolution of Plio–Pleistocene alluvial and lacustrine deposits of Fucino Basin (central Italy)

    Microsoft Academic Search

    Gian Paolo Cavinato; Claudio Carusi; Massimo Dall'Asta; Enrico Miccadei; Tommaso Piacentini

    2002-01-01

    The Fucino Basin was the greatest lake of the central Italy, which was completely drained at the end of 19th century. The basin is an intramontane half-graben filled by Plio–Quaternary alluvial and lacustrine deposits located in the central part of the Apennines chain, which was formed in Upper Pliocene and in Quaternary time by the extensional tectonic activity.The analysis of

  5. Luminescence dating of quaternary deposits in geology in Brazil.

    PubMed

    Tatumi, Sonia Hatsue; Gozzi, Giuliano; Yee, Márcio; de Oliveira, Victor Inácio; Sallun, Alethéa Ernandes Martins; Suguio, Kenitiro

    2006-01-01

    In the present work, systematic dating by luminescence methods has been done on 50 Quaternary geological samples within the study area of São Paulo State, Brazil. Bleaching experiments showed that residual TL intensity of 375 degrees C peak, of the quartz, was obtained after 10 h of sunlight exposition. Intensities decays of the 325 and 375 degrees C TL peaks can be fitted using second order exponential equation. Paleodose values were evaluated using regeneration methods with multiple aliquots. Samples dated indicate preliminary ages varying from 9 +/- 1 to 935 +/- 130 ka for colluvio-elluvial deposits, and from 17 +/- 2 to 215 +/- 30 ka for alluvial deposits of the study area. They cover four peneplained surfaces shaped during the Quaternary: I (1000-400 ka), II (400-120 ka), III (120-10 ka) and IV (10 ka until today), in decreasing order. PMID:16782979

  6. A model of the Quaternary geological deposits of Bucharest City

    NASA Astrophysics Data System (ADS)

    Serpescu, Irina; Radu, Emil; Radu Gogu, Constantin; Amine Boukhemacha, Mohamed; Gaitanaru, Dragos; Bica, Ioan

    2013-04-01

    Bucharest city is located in the central part of the Moesic Platform, in the Romanian Plain with micro-relief resulting from erosion and sedimentary processes which extended along the valleys of the Dambovita River to the south and the Colentina River to the north. The city is located in the axial area of a syncline where the thickness of the sedimentary deposits is up to 1000 m. The area lies on a rigid base is made of metamorphites, and various igneous intrusions (granodiorite, granite). The sedimentary deposits covering this rigid base are made by different phases of erosion and sedimentary processes of marine, lacustrian or continental sediments ending with Quaternary sediments. As a result, different alluvial deposits (such as piedmont, deltaic, alluvial cones, terrace, waterside and lacustrine deposits) can be met. Furthermore one also can find loess deposits which in turn cover totally the older deposits where rivers dug the present relief. To highlight the spatial extent of these geological structures, a geological model of Bucharest city is developed. A set of information coming from different sources as geological and geotechnical boreholes showing a detailed geological and lithological description, geological and topographical maps, geological and hydrogeological reports have been used to develop the 3D geological model of this region. 33 geological cross sections were defined and interpreted by using lithological and sedimentological criteria. Using these geological cross sections and prior geological knowledge, the Quaternary deposits have been described and classified into 6 structural units given from top to down as follows: (1) Superficial deposits represented by loess and anthropogenic materials. The geological model indicates that these deposits show a sporadic development becoming more concentrated in the central west part of the city. (2) Colentina Formations composed by of poorly sorted, cross-stratified sand and gravel with clayey lens indicating a high energy deposition environment. The geological model indicates more accentuate vertical lithological heterogeneity than a horizontal one as well as a decrease of the Colentina Formation thickness. (3) Intermediary deposits represented by silty-clay with fine sand intercalation indicating a mixed regime with limited lakes and dry lands. (4) Mostistea Formation made of sediments with a variety of grain size, from fine sand to coarse sand with small intercalations of gravels and scrap of woods. It was found that areas where the Intermediary deposits are less developed making the Colentina Formation in direct connection to Mostistea Formation. (5) Marly Complex composed by a succession of marls and clays with lenticular sandy intercalations indicating a fluvial-lacustrine environment. (6) Fratesti Strata made of sand and gravel which includes A, B and C Fratesti levels.

  7. Late Quaternary alluvial processes in the north piedmont of Wutai Mountain in the graben system of north China and the influencing factors

    NASA Astrophysics Data System (ADS)

    Zhang, S.; Gong, Z.; Ding, R.; Li, T.

    2012-12-01

    The alluvial processes in the piedmont may be controlled by tectonics, climate fluctuations and base level of erosion, etc. To distinguish the contributions of each factors is a hot field in fluvial geomorphology. The north piedmont of Wutai Mountain in Shanxi graben is an ideal area for this kind of study. The piedmont fault is very active with a slip rate of no less than 1 millimeter per year in late Quaternary. This semiarid region experienced significant climatic fluctuations in Quaternary time which is indicated by striking contrast in colors between loess and paleosoils in loess strata. The stratigraphic sequence of alluvial fans in late Pleistocene and Holocene is established through field surveying and trenching. Ages of the strata have been well constrained by the method of radiocarbon dating. It is discovered that the alluvial processes in front of the mountain were strong and weak alternately. The strong periods were from 32 ka to 29 ka B.P., from 7.5 ka to 4.7 ka B.P., and since 1 ka B.P., when coarse-grained sediments deposited and the sediment rate is relatively high. The other times are weak periods when fine-grained sediments deposited and the sediment rate is much lower. The three strong periods correspond either with the transform stages from warm to cool climates, or with the intense fluctuation stage after the maximum of warm climate. These three periods share a common feature of intense fluctuations of weather whose amplitudes are larger than other periods. According to former studies on Holocene paleoearthquakes about Wutai Mountain piedmont fault, two events happened in strong periods of alluvial processes, one event in weak period. Strong earthquakes may lead to landslides and rock-falls in mountain area, which increment the clastic provenance and contribute to alluvial processes, but the limited information of paleoearthquakes cannot support a salient effect of big earthquakes on alluvial processes in front of mountain. As our preliminary view, fault slips provided the space for deposition and slope of river bed, and climatic changes controlled the alternations of strong or weak alluvial processes. In the strongest fluctuations stage of climates, the vegetation degraded, physical weathering strengthened and storms easily led to flood, which contributed to erosions in mountain area and diluvium in front of mountain. This research deepens our understanding on the influencing factors of alluvial processes in semiarid area.

  8. A Quaternary volcanic ash deposit in western Missouri

    SciTech Connect

    Emerson, J.W. (Central Missouri State Univ., Warrensburg, MO (United States))

    1993-03-01

    Quaternary volcanic ash has been found in more than fifty localities in the midwest. The most widespread deposits originated from the Long Valley caldera, California; the Jemez calderas, New Mexico; or the Yellowstone caldera, Wyoming. Fission track dating has grouped the deposits into six separate ash falls ranging from 700,000--2,000,000 years old. A small volcanic ash deposit in western Missouri may be correlative with those found along the Kansas and Marais de Cygnes rivers in eastern Kansas. The ash deposit is in Northwest Bates County Missouri, exposed along a tributary to Miami Creek, four miles east of the Kansas state line. The ash layer is interbedded with alluvial terrace deposits and ranges from fifteen to thirty inches in thickness. It is inferred to have been deposited in a pond or oxbow lake. The color is white with a pale yellow tinge (Munsell 10YR 8/2). Shard examination shows that about 70% are flat bubble-wall types, about 20% have straight ridges, less than 10% are bubble-junction, and only a trace are vesicular. The closest known volcanic ash occurrence is an ash outcropping in a Kansas river terrace near DeSoto, KS, forty-five miles to the northwest. The DeSoto deposit has been identified as the .62 m.y. Lava Creek B ash from the Yellowstone caldera. A preliminary correlation of the Missouri ash with the DeSoto ash is based on similar shard morphology and color.

  9. Faulting and folding in quaternary deposits of Tehran’s piedmont (Iran)

    NASA Astrophysics Data System (ADS)

    Abbassi, M. R.; Farbod, Y.

    2009-04-01

    Tehran lies on the southern flank of the Central Alborz, an active mountain belt characterized by many historical earthquakes, some of which have affected Tehran itself. The border between the Alborz Mountain and the Tehran's piedmont (northern part of Tehran City) is marked by the North Tehran Fault (NTF), dividing the Eocene rock formation from the alluvial units of different ages (Early Pleistocene to the recent alluvium). A detail mapping of the piedmont, combined with structural study reveal that two active thrust faults (situated south of the NTF) are of importance for hazard assessment of the City. The geomorphological evidences along the NTF are not in agreement with an active fault, indicating that the fault activity may have been shifted southward. Furthermore differentiation of newly recognized alluvial units and their inferred ages, together with the mapped fault pattern permit us to characterize the Quaternary deformation. The Late Pleistocene alluvial deposits consist of three alluvial fans among them the youngest one together with the modern alluvial fan defines the Holocene deposit. The present deformation in the piedmont is accommodated along vertically left-lateral strike-slip faults and low-angle thrust faults trending in range from N070 to N110E.

  10. Hydrogeologic features of the alluvial deposits in the Greybull River valley, Bighorn Basin, Wyoming

    USGS Publications Warehouse

    Cooley, M.E.; Head, W.J.

    1979-01-01

    The alluvial aquifer along the Greybull River in Wyoming, consists principally of the Greybull terrace doposits and flood-plain alluvium but also includes Burlington terrace deposits east of Burlington, the McKinnie terrace, and the younger, generally undissected alluvial-fan deposits. Well-log data and 18 surface-resistivity measurements at four localities indicate that the thickness of the alluvial aquifer is as much as 60 feet thick only near Burlington and Otto. The most favorable area for development of ground water from the alluvial aquifer is near Burlington and Otto where relatively large amounts of water can be obtained from the Greybull terrace deposits and the flood-plain alluvium. Elsewhere, the deposits of the alluvial aquifer yield only small amounts of water to wells. (Woodard-USGS)

  11. Quaternary allostratigraphy of surficial deposit map units at Yucca Mountain, Nevada: A progress report

    SciTech Connect

    Lundstrom, S.C. (Geological Survey, Las Vegas, NV (United States)); Wesling, J.R.; Swan, F.H. (Geomatrix Consultants, San Francisco, CA (United States)); Taylor, E.M.; Whitney, J.W. (Geological Survey, Denver, CO (United States))

    1993-04-01

    Surficial geologic mapping at Yucca Mountain, Nevada, is relevant to site characterization studies of paleoclimate, tectonics, erosion, flood hazards, and water infiltration. Alluvial, colluvial, and eolian allostratigraphic map units are defined on the basis of age-related surface characteristics and soil development, as well as lithology and sedimentology indicative of provenance and depositional mode. In gravelly alluvial units, which include interbedded debris flows, the authors observe a useful qualitative correlation between surface and soil properties. Map units of estimated middle Pleistocene age typically have a well-developed, varnished desert pavement, and minimal erosional and preserved depositional microrelief, associated with a soil with a reddened Bt horizon and stage 3 carbonate and silica morphology. Older units have greater erosional relief, an eroded argillic horizon and stage 4 carbonate morphology, whereas younger units have greater preservation of depositional morphology, but lack well-developed pavements, rock varnish, and Bt and Kqm soil horizons. Trench and gully-wall exposures show that alluvial, colluvial and eolian dominated surface units are underlain by multiple buried soils separating sedimentologically similar deposits; this stratigraphy increases the potential for understanding the long-term Quaternary paleoenvironmental history of Yucca Mountain. Age estimates for allostratigraphic units, presently based on uranium-trend dating and regional correlation using soil development, will be further constrained by ongoing dating studies that include tephra identification, uranium-series disequilibrium, and thermoluminescence methods.

  12. Physicochemical characteristics of the soils developed from alluvial deposits on Chongming Island in Shanghai, China

    Microsoft Academic Search

    Ming He; Katsutoshi Sakurai; Guoqing Wang; Zonghui Chen; Yi Shu; Jinjin Xu

    2003-01-01

    Characterization of the physico-chemical properties of the soils collected from Chongming Island in Shanghai, China, which is the largest alluvial island with a total area of about 1,070 km in the world, has been conducted in order to investigate the current status of agricultural soils, with special reference to the effect of alluvial deposits on the development and utilization of

  13. Texture and depositional history of near-surface alluvial deposits in the central part of the western San Joaquin Valley, California

    USGS Publications Warehouse

    Laudon, Julie; Belitz, Kenneth

    1989-01-01

    Saline conditions and associated high levels of selenium and other soluble trace elements in soil, shallow ground water, and agricultural drain water of the western San Joaquin Valley, California, have prompted a study of the texture of near-surface alluvial deposits in the central part of the western valley. Texture is characterized by the percentage of coarse-grained sediment present within a specified subsurface depth interval and is used as a basis for mapping the upper 50 feet of deposits. Resulting quantitative descriptions of the deposits are used to interpret the late Quaternary history of the area. Three hydrogeologic units--Coast Range alluvium, flood-basin deposits, and Sierran sand--can be recognized in the upper 50 feet of deposits in the central part of the western San Joaquin Valley. The upper 30 feet of Coast Range alluvium and the adjacent 5 to 35 feet of flood-basin deposits are predominantly fine grained. These fine-grained Coast Range deposits are underlain by coarse-grained channel deposits. The fine-grained flood basin deposits are underlain by coarse-grained Sierran sand. The extent and orientation of channel deposits below 20 feet in the Coast Range alluvium indicate that streams draining the Coast Range may have been tributary to the axial stream that deposited the Sierran sand and that streamflow may have been to the southeast. The fining-upward stratigraphic sequence in the upper 50 feet of deposits and the headward retreat of tributary stream channels from the valley trough with time support a recent hypothesis of climatic control of alluviation in the western San Joaquin Valley.

  14. Late Quaternary landscape evolution in the Kunlun Mountains and Qaidam Basin, Northern Tibet: A framework for examining the links between glaciation, lake level changes and alluvial fan formation

    USGS Publications Warehouse

    Owen, L.A.; Finkel, R.C.; Haizhou, M.; Barnard, P.L.

    2006-01-01

    The Qaidam Basin in Northern Tibet is one of the largest hyper-arid intermontane basins on Earth. Alluvial fans, pediment surfaces, shorelines and a thick succession of sediments within the basin, coupled with moraines and associated landforms in the adjacent high mountain catchments of the Kunlun Mountains, record a complex history of Late Quaternary paleoenvironmental change and landscape evolution. The region provides an ideal natural laboratory to examine the interaction between tectonics and climate within a continent-continent collision zone, and to quantify rates of landscape evolution as controlled by climate and the associated glacial and hydrological changes in hyper-arid and adjacent high-altitude environments. Geomorphic mapping, analysis of landforms and sediments, and terrestrial cosmogenic radionuclide surface exposure and optically stimulated luminescence dating serve to define the timing of formation of Late Quaternary landforms along the southern and northwestern margins of the Qaidam Basin, and in the Burhan Budai Shan of the Kunlun Mountains adjacent to the basin on the south. These dates provide a framework that suggests links between climatic amelioration, deglaciation, lake desiccation and alluvial fan evolution. At least three glacial advances are defined in the Burham Budai Shan of the Kunlun Mountains. On the northern side of this range these occurred in the penultimate glacial cycle or early in the last glacial cycle, during the Last Glacial Maximum (LGM)/Lateglacial and during the Holocene. On the south side of the range, advances occurred during the penultimate glacial cycle, MIS-3, and possibly the LGM, Lateglacial or Holocene. Several distinct phases of alluvial fan sedimentation are likewise defined. Alluvial fans formed on the southern side of the Kunlun Mountains prior to 200 ka. Ice-contact alluvial fans formed during the penultimate glacial and during MIS-3. Extensive incised alluvial fans that form the main valley fills north of the Burham Budai and extend into the Qaidam Basin are dated to ???30 ka. These ages suggest that there was a period of alluvial fan aggradation and valley filling that persisted until desiccation of the large lakes in the Qaidam Basin post ???30 ka led to base level lowering and active incision of streams into the valley fills. The continued Lateglacial and Holocene desiccation likely led to further degradation of the valley fills. Ice wedge casts in the Qaidam Basin date to ???15 ka, indicating significant Lateglacial climatic amelioration, while Holocene loess deposits north of the Burham Bdudai suggest that aridity has increased in the region since the early Holocene. From these observations, we infer that the major landscape changes within high glaciated mountains and their adjacent hyper-arid intermontane basins, such as the Kunlun Mountains and Qaidam Basin, occur rapidly over millennial timescales during periods of climatic instability. ?? 2006 Elsevier Ltd and INQUA.

  15. Quaternary alluvial fans in the Gobi of southern Mongolia: evidence for neotectonics and climate change

    Microsoft Academic Search

    L. A. Owen; B. F. Windley; W. D. Cunningham; J. Badamgarav; D. Dorjnamjaa

    1997-01-01

    Alluvial fans in southern Monglia occur along a group of narrow discontinuous mountain ranges which formed as transpressional uplifts along a series of strike-slip faults. They provide information on the nature of neotectonic activity in the eastern Gobi Altai range and on palaeoclimate change. Alluvial fan formation was dominated by various geomorphological processes largely controlled by climatic changes related to

  16. Geohydrology of the alluvial and terrace deposits of the North Canadian River from Oklahoma City to Eufaula Lake, central Oklahoma

    USGS Publications Warehouse

    Havens, J.S.

    1989-01-01

    This investigation was undertaken to describe the geohydrology of the alluvial and terrace deposits along the North Canadian River between Lake Overholser and Eufaula Lake, an area of about 1,835 square miles, and to determine the maximum annual yield of ground water. A 1982 water-level map of the alluvial and terrace aquifer was prepared using field data and published records. Data from test holes and other data from the files of the U.S. Geological Survey and the Oklahoma Water Resources Board were used to establish the approximate thickness of the alluvial and terrace deposits. The North Canadian River from Lake Overholser, near Oklahoma City, to Eufaula Lake is paralleled by a 2- to 3-mile wide band of alluvium. Scattered terrace deposits on either side of the alluvium reach an extreme width of 8 miles. Rocks of Permian age bound the alluvial and terrace deposits from the west to the midpoint of the study area; Pennsylvanian rocks bound the alluvial and terrace deposits from that point eastward. Three major aquifers are present in the study area: the alluvial and terrace aquifer, consisting of alluvium and terrace deposits of Quaternary age in a narrow band on either side of the North Canadian River; the Garber-Wellington aquifer of Permian age, consisting of an upper unconfined zone and a lower confined zone separated by relatively impermeable shales; and the Ada-Vamoosa aquifer of Pennsylvanian age. At locations were the alluvial and terrace aquifer overlies either of the other aquifers, there is hydraulic continuity between the alluvial and terrace aquifer and the other aquifers, and water levels are the same. Most large-scale municipal and industrial pumping from the Garber-Wellington aquifer is from the lower zone and has little discernible effect upon the alluvial and terrace aquifer. The total estimated base flow of the North Canadian River for the studied reach is 264 cubic feet per second. Evapotranspiration from the basin in August is about 60 cubic feet per second for the North Canadian River from Lake Overholser to a measuring station above Eufaula Lake. Estimated recharge rates to the alluvial and terrace aquifer in the basin range from 1.7 inches at the west edge of the study area to 7.0 inches at the east edge. Total permitted withdrawal from the aquifer, according to records of the Oklahoma Water Resources Board, ranged from 2,107 acre-feet per year in 1942 to about 21,415 acre-feet per year in 1982. Simulations of the alluvial and terrace aquifer from Lake Overholser to Eufaula Lake were made using a finite-difference model developed by McDonald and Harbaugh (1984). The area of the aquifers was subdivided into a finite-difference grid having 30 rows and 57 columns with cells measuring 1 mile in the north-south direction and 2 miles in the east-west direction. The model was calibrated in two steps: A steady-state calibration simulated head distribution prior to extensive pumping of the aquifer in 1942, and a transient calibration simulated head distribution after extensive pumpage. The final horizontal hydraulic conductivity used for the alluvial and terrace aquifer was 0.0036 feet per second (310 feet per day) at all locations. The recharge rate for the alluvial and terrace aquifer ranged from 1.7 inch per year in the west to 7.0 inches per year in the east, and averaged about 3.3 inches per year. A specific yield of 15 percent was used for the transient simulation. Permitted pumpage for 1942 through 1982 was used in the digital model to estimate the annual volume of water in storage in the alluvial and terrace aquifer for the years for this time period. The 1982 permitted pumpage rates were used for projections for 1983 to 2020. The estimated volume of water in storage was 1,940,000 acre-feet in 1982. Because the estimated recharge rate is equal to the allowed pumpage rate in 1982, the projected volume of water in storage in both 1993 and 2020 was 1,890,000 acre-feet.

  17. Alluvial deposits and plant distribution in an Amazonian lowland megafan

    NASA Astrophysics Data System (ADS)

    Zani, H.; Rossetti, D.; Cremon; Cohen, M.; Pessenda, L. C.

    2012-12-01

    A large volume of sandy alluvial deposits (> 1000 km2) characterizes a flat wetland in northern Amazonia. These have been recently described as the sedimentary record of a megafan system, which have a distinct triangular shape produced by highly migratory distributary rivers. The vegetation map suggests that this megafan is dominated by open vegetation in sharp contact with the surround rainforest. Understanding the relationship between geomorphological processes and vegetation distribution is crucial to decipher and conserve the biodiversity in this Amazonian ecosystem. In this study we interpret plant dynamics over time, and investigate its potential control by sedimentary processes during landscape evolution. The study area is located in the Viruá National Park. Two field campaigns were undertaken in the dry seasons of 2010 and 2011 and the sampling sites were selected by combining accessibility and representativeness. Vegetation contrasts were recorded along a transect in the medial section of the Viruá megafan. Due to the absence of outcrops, samples were extracted using a core device, which allowed sampling up to a depth of 7.5 m. All cores were opened and described in the field, with 5 cm3 samples collected at 20 cm intervals. The ?13C of organic matter was used as a proxy to distinguish between C3 and C4 plant communities. The chronology was established based on radiocarbon dating. The results suggest that the cores from forested areas show the most depleted values of ?13C, ranging from -32.16 to -27.28‰. The ?13C curve in these areas displays typical C3 land plant values for the entire record, which covers most of the Holocene. This finding indicates that either the vegetation remained stable over time or the sites were dominated by aquatic environments with freshwater plants before forest establishment. The cores from the open vegetation areas show a progressive upward enrichment in ?13C values, which range from -28.50 to -19.59‰. This trend is more pronounced after de mid-Holocene, suggesting that the open vegetation, represented mostly by C4 land plants, evolved only more recently. Based on our isotope data, a model is proposed taking into account the influence of sedimentary dynamics on the modern pattern of plan distribution. The establishment of open vegetation occurred at different times depending on location over the megafan area, varying from around 3,000 to 6,400 cal yrs BP. As sedimentation took place, areas located far from the surrounding rainforest were prone to inputs of organic matter derived from open vegetation, whereas the contribution of organic matter derived from arboreous vegetation increases toward the areas located closer to the rainforest. In general, open vegetation is constrained to depositional sites that remained active until relatively recent Holocene times, while surrounding areas with a relatively older geological history are covered by dense forest. The results presented here consist in a striking example of the influence of sedimentary processes during the Late Pleistocene-Holocene on the development of modern plants of this Amazonian lowland.

  18. Hydrogeologic features of the alluvial deposits in the Owl Creek Valley, Bighorn Basin, Wyoming

    USGS Publications Warehouse

    Cooley, M.E.; Head, W.J.

    1982-01-01

    The alluvial acquifer principally of the flood-plain alluvium and part of the Arapahoe Ranch terrace deposits and consists subordinately of alluvial-fan deposits. Thickness of the alluvial aquifer is generally 20 to 40 feet. Dissolved-solids concentration of water in the alluvial aquifer ranges from about 500 to more than 3,000 milligrams per liter. The most favorable areas for groundwater development are the flood-plain alluvium and part of the Arapahoe Ranch terrace deposits; however, in much of these units, the water contains more than 2,000 milligrams per liter of dissolved solids. Measurements of specific conductance of the flow of Owl Creek indicate a progressive increase in the down stream direction and range between 15 and 355 micromhos per centimeter at 25C per mile. The increases are due to return flow of irrigation water, inflow from tributaries, and inflow from groundwater. Conspicuous terraces in Owl Creek Valley included an unnamed terrace at 500 feet above Owl Creek, the Embar Ranch terrace 160 to 120 feet above the creek, and the Arapahoe Ranch terrace 50 to 20 feet above the creek. (USGS)

  19. Clay sized fraction and powdered whole-rock X-ray analyses from alluvial basin deposits in central and southern New Mexico

    USGS Publications Warehouse

    Anderholm, S.K.

    1985-01-01

    As part of the study of the water quality and geochemistry of Southwest Alluvial Basins (SWAB) in parts of Colorado, New Mexico, and Texas, which is a Regional Aquifer-System Analysis (RASA) program, whole rock x-ray analysis and clay-size fraction mineralogy (x-ray) analysis of selected samples from alluvial basin deposits were done to investigate the types of minerals and clay types present in the aquifers. This was done to determine the plausible minerals and clay types in the aquifers that may be reacting with groundwater and affecting the water quality. The purpose of this report is only to present the whole rock x-ray and clay-fraction mineralogy data. Nineteen surface samples or samples from outcrop of Tertiary and Quaternary alluvial basin deposits in the central and southern Rio Grande rift were collected and analyzed. The analysis of the samples consisted of grain size analysis, and clay-size fraction mineralogy and semiquantitative analysis of the relative abundance of different clay mineral groups present. (USGS)

  20. Soils developed from alluvial and proluvial deposits in the Gröndalselva River valley in West Spitsbergen

    NASA Astrophysics Data System (ADS)

    Pereverzev, V. N.; Litvinova, T. I.

    2012-05-01

    The genetic characterization of soils developed from alluvial and proluvial deposits in the Gröndalselva River valley (West Spitsbergen) is presented. These soils are compared with analogous soils formed on marine terraces along the coasts of Isfjord and Grönfjord. Gray-humus (soddy) soils with an O-AY-C profile have been described on parent materials of different origins, including alluvial and proluvial sediments. The texture of the soils in the Gröndalselva River valley varies from medium to heavy loam and differs from the texture of the soils on other geomorphic positions in the higher content of fine particles. The soils developed from the alluvial deposits are characterized by their richer mineralogical and chemical composition in comparison with the soils developed from proluvial deposits, marine deposits, and bedrocks. All the deposits are impoverished in CaO. No differentiation of the chemical composition of the soils along the soil profiles has been found in the soils of the coastal areas and the river valley. Some accumulation of oxalate-soluble Al and Fe compounds takes place in the uppermost mineral horizon. The soils of all the geomorphic positions have a high humus content and a high exchange capacity.

  1. Sedimentary facies of alluvial fan deposits, Death Valley, California

    SciTech Connect

    Middleton, G.V. (McMaster Univ., Hamilton, Ontario (Canada))

    1992-01-01

    Fans in Death Valley include both diamicts and bedded gravels. Seven facies may be recognized. The diamicts include: (1) matrix-rich, coarse wackestones; (2) thin, matrix-rich, fine wackestones, that may show grading; (3) matrix-poor, coarse packstones, transitional to wackestones. The bedded facies include: (4) weakly bedded, poorly sorted packstones or grainstones, that show patchy imbrication, and cut-and-fill structures; (5) packed, imbricated cobble lenses, generally interbedded in facies 4; (6) distinctly bedded gravels, that are better bedded, finer and better sorted, and show better imbrication than facies 4, but still do not show clear separation of sand and gravel beds; (7) backfill cross-bedded gravels. Sand beds are not seen in fan deposits. Sand is present in eolian deposits, as plane-laminated, back-eddy deposits in Death Valley Wash, and as laminated or rippled sand in the Amargosa River. The most remarkable features of the fan deposits are the very weak segregation of sand and gravel, and the complete absence of any lower flow-regime structures produced by ripples or dunes. During floods, the slope of fan and even large wash surfaces is steep enough to produce upper flow regimes. There are also very few trends in facies abundance down fans: most fans in Death Valley itself are not strongly dominated by debris flow deposits (diamicts). The facies characteristics of a given fan vary little from proximal to distal regions, but may differ strongly from the facies seen in adjacent fans. Ancient deposits that show clear segregation of gravel from cross-bedded sand beds, or strong proximal to distal facies transitions, must have been deposited in environments quite different from Death Valley.

  2. Quaternary stratigraphy, sediment characteristics and geochemistry of arsenic-contaminated alluvial aquifers in the Ganges-Brahmaputra floodplain in central Bangladesh

    NASA Astrophysics Data System (ADS)

    Shamsudduha, M.; Uddin, A.; Saunders, J. A.; Lee, M.-K.

    2008-07-01

    This study focuses on the Quaternary stratigraphy, sediment composition, mineralogy, and geochemistry of arsenic (As)-contaminated alluvial aquifers in the Ganges-Brahmaputra floodplain in the central Bangladesh. Arsenic concentrations in 85 tubewells in Manikganj area, 70 km northwest of Dhaka City, range from 0.25 µg/L to 191 µg/L with a mean concentration of 33 µg/L. Groundwater is mainly Ca-HCO3 type with high concentrations of dissolved As, Fe, and Mn, but low level of SO4. The uppermost aquifer occurs between 10 m and 80 m below the surface that has a mean arsenic concentration of 35 µg/L. Deeper aquifer (> 100 m depth) has a mean arsenic concentration of 18 µg/L. Sediments in the upper aquifer are mostly gray to dark-gray, whereas sediments in the deep aquifer are mostly yellowing-gray to brown. Quartz, feldspar, mica, hornblende, garnet, kyanite, tourmaline, magnetite, ilmenite are the major minerals in sediments from both aquifers. Biotite and potassium feldspar are dominant in shallow aquifer, although plagioclase feldspar and garnet are abundant in deep aquifer sediments. Sediment composition suggests a mixed provenance with sediment supplies from both orogenic belts and cratons. High arsenic concentrations in sediments are found within the upper 50 m in drilled core samples. Statistical analysis shows that As, Fe, Mn, Ca, and P are strongly correlated in sediments. Concentrations of Cd, Cu, Ni, Zn, and Bi also show strong correlations with arsenic in the Manikganj sediment cores. Authigenic goethite concretions, possibly formed by bacteria, are found in the shallow sediments, which contain arsenic of a concentration as high as 8.8 mg/kg. High arsenic concentrations in aquifers are associated with fine-grained sediments that were derived mostly from the recycled orogens and relatively rapidly deposited mainly by meandering channels during the Early to Middle Holocene rising sea-level conditions.

  3. Quaternary stratigraphy, sediment characteristics and geochemistry of arsenic-contaminated alluvial aquifers in the Ganges-Brahmaputra floodplain in central Bangladesh.

    PubMed

    Shamsudduha, M; Uddin, A; Saunders, J A; Lee, M-K

    2008-07-29

    This study focuses on the Quaternary stratigraphy, sediment composition, mineralogy, and geochemistry of arsenic (As)-contaminated alluvial aquifers in the Ganges-Brahmaputra floodplain in the central Bangladesh. Arsenic concentrations in 85 tubewells in Manikganj area, 70 km northwest of Dhaka City, range from 0.25 microg/L to 191 microg/L with a mean concentration of 33 microg/L. Groundwater is mainly Ca-HCO(3) type with high concentrations of dissolved As, Fe, and Mn, but low level of SO(4). The uppermost aquifer occurs between 10 m and 80 m below the surface that has a mean arsenic concentration of 35 microg/L. Deeper aquifer (>100 m depth) has a mean arsenic concentration of 18 microg/L. Sediments in the upper aquifer are mostly gray to dark-gray, whereas sediments in the deep aquifer are mostly yellowing-gray to brown. Quartz, feldspar, mica, hornblende, garnet, kyanite, tourmaline, magnetite, ilmenite are the major minerals in sediments from both aquifers. Biotite and potassium feldspar are dominant in shallow aquifer, although plagioclase feldspar and garnet are abundant in deep aquifer sediments. Sediment composition suggests a mixed provenance with sediment supplies from both orogenic belts and cratons. High arsenic concentrations in sediments are found within the upper 50 m in drilled core samples. Statistical analysis shows that As, Fe, Mn, Ca, and P are strongly correlated in sediments. Concentrations of Cd, Cu, Ni, Zn, and Bi also show strong correlations with arsenic in the Manikganj sediment cores. Authigenic goethite concretions, possibly formed by bacteria, are found in the shallow sediments, which contain arsenic of a concentration as high as 8.8 mg/kg. High arsenic concentrations in aquifers are associated with fine-grained sediments that were derived mostly from the recycled orogens and relatively rapidly deposited mainly by meandering channels during the Early to Middle Holocene rising sea-level conditions. PMID:18502538

  4. Quaternary landscape development, alluvial fan chronology and erosion of the Mecca Hills at the southern end of the San Andreas Fault zone

    NASA Astrophysics Data System (ADS)

    Gray, Harrison J.; Owen, Lewis A.; Dietsch, Craig; Beck, Richard A.; Caffee, Marc A.; Finkel, Robert C.; Mahan, Shannon A.

    2014-12-01

    Quantitative geomorphic analysis combined with cosmogenic nuclide 10Be-based geochronology and denudation rates have been used to further the understanding of the Quaternary landscape development of the Mecca Hills, a zone of transpressional uplift along the southern end of the San Andreas Fault, in southern California. The similar timing of convergent uplifts along the San Andreas Fault with the initiation of the sub-parallel San Jacinto Fault suggest a possible link between the two tectonic events. The ages of alluvial fans and the rates of catchment-wide denudation have been integrated to assess the relative influence of climate and tectonic uplift on the development of catchments within the Mecca Hills. Ages for major geomorphic surfaces based on 10Be surface exposure dating of boulders and 10Be depth profiles define the timing of surface stabilization to 2.6 +5.6/-1.3 ka (Qyf1 surface), 67.2 ± 5.3 ka (Qvof2 surface), and 280 ± 24 ka (Qvof1 surface). Comparison of 10Be measurements from active channel deposits (Qac) and fluvial terraces (Qt) illustrate a complex history of erosion, sediment storage, and sediment transport in this environment. Beryllium-10 catchment-wide denudation rates range from 19.9 ± 3.2 to 149 ± 22.5 m/Ma and demonstrate strong correlations with mean catchment slope and with total active fault length normalized by catchment area. The lack of strong correlation with other geomorphic variables suggests that tectonic uplift and rock weakening have the greatest control. The currently measured topography and denudation rates across the Mecca Hills may be most consistent with a model of radial topographic growth in contrast to a model based on the rapid uplift and advection of crust.

  5. Late Quaternary carbonate deposition at the bottom of the world

    NASA Astrophysics Data System (ADS)

    Frank, Tracy D.; James, Noel P.; Bone, Yvonne; Malcolm, Isabelle; Bobak, Lindsey E.

    2014-05-01

    Carbonate sediments on polar shelves hold great potential for improving understanding of climate and oceanography in regions of the globe that are particularly sensitive to global change. Such deposits have, however, not received much attention from sedimentologists and thus remain poorly understood. This study investigates the distribution, composition, diagenesis, and stratigraphic context of Late Quaternary calcareous sediments recovered in 15 piston cores from the Ross Sea shelf, Antarctica. Results are used to develop a depositional model for carbonate deposition on glaciated, polar shelves. The utility of the deposits as analogs for the ancient record is explored. In the Ross Sea, carbonate-rich lithofacies, consisting of poorly sorted skeletal sand and gravel, are concentrated in the west and along the outer reaches of the continental shelf and upper slope. Analysis of fossil assemblages shows that deposits were produced by numerous low-diversity benthic communities dominated locally by stylasterine hydrocorals, barnacles, or bryozoans. Radiocarbon dating indicates that carbonate sedimentation was episodic, corresponding to times of reduced siliciclastic deposition. Most accumulation occurred during a time of glacial expansion in the lead-up to the Last Glacial Maximum. A more recent interval of carbonate accumulation postdates the early Holocene sea level rise and the establishment of the modern grounding line for the Ross Ice Shelf. When carbonate factories were inactive, fossil debris was subjected to infestation by bioeroders, dissolution, fragmentation, and physical reworking. This study reveals the episodic nature of carbonate deposition in polar settings and a reciprocal relationship with processes that deliver and redistribute siliciclastic debris. Carbonate production is most active during colder periods of the glacial-interglacial cycle, a potential new sedimentological paradigm for polar carbonate systems. Low accumulation rates and long residence times on the seafloor leave sediments vulnerable to significant post-depositional modification, processes that profoundly affect the appearance of deposits as they enter the rock record. Comparison with other examples of polar carbonates highlights the utility of these Late Quaternary deposits as a well-constrained analog that can aid in the recognition and interpretation of similar deposits from the ancient record.

  6. Local recharge processes in glacial and alluvial deposits of a temperate catchment

    NASA Astrophysics Data System (ADS)

    Fragalà, Federico A.; Parkin, Geoff

    2010-07-01

    SummaryThis study demonstrates that the composition and structure of Quaternary deposits and topography significantly influence rates of recharge and distribution of diffuse agricultural pollution at the hillslope scale. Analyses were made of vertical profiles of naturally-occurring chloride and nitrate, and artificially introduced bromide, in unsaturated and saturated sections of borehole cores of glacial till and alluvium under different land uses in the Upper Eden valley (UK). Estimates of local potential recharge were made based on chloride mass balance and nitrate peak methods. Persistent chloride bulges below the root zone were observed, and are interpreted to result from filtration processes at lithological boundaries. Changes in the shape of chloride profiles downslope, corroborated by nitrate profiles, indicate the roles of surface or near-surface runoff and runon, and the existence of lateral subsurface flows at depth. These findings have implications for estimation of recharge rates through unsaturated zones in Quaternary deposits, and the interpretation of potential 'hot-spots' of diffuse agrochemicals, particularly nitrates, moving through Quaternary deposits into groundwater.

  7. Mineral Occurrence, Translocation, and Weathering in Soils Developed on Four Types of Carbonate and Non-carbonate Alluvial Fan Deposits in Mojave Desert, Southeastern California

    NASA Astrophysics Data System (ADS)

    Deng, Y.; McDonald, E. V.

    2007-12-01

    Soil geomorphology and mineralogy can reveal important clues about Quaternary climate change and geochemical process occurring in desert soils. We investigated (1) the mineral transformation in desert soils developed on four types of alluvial fans (carbonate and non-carbonate) under the same conditions of climate and landscape evolution; and (2) the effects of age, parent materials, and eolian processes on the transformation and translocation of the minerals. Four types of alluvial-fan deposits along the Providence Mountains piedmonts, Mojave Desert, southeastern California, USA were studied: (1) carbonate rocks, primarily limestone and marble (LS), (2) fine-grained rhyodacite and rhyolitic tuff mixed with plutonic and carbonate rocks (VX), (3) fine- to coarse- grained mixed plutonic (PM) rocks, and (4) coarse-grained quartz monzonite (QM). These juxtaposed fan deposits are physically correlated in a small area (about 20 km by 15 km) and experienced the same climatic changes in the late Pleistocene and Holocene. The soils show characteristic mineral compositions of arid/semiarid soils: calcite is present in nearly all of the samples, and a few of the oldest soils contain gypsum and soluble salts. Parent material has profound influence on clay mineral composition of the soils: (1) talc were observed only in soils developed on the volcanic mixture fan deposits, and talc occurs in all horizons; (2) palygorskite occur mainly in the petrocalcic (Bkm) of old soils developed on the LS and VX fan deposits, indicating pedogenic origin; (3) chlorite was observed mainly in soils developed on VX fan deposits (all ages) and on some LS deposits, but it is absent in soils developed on PM and QM fan deposits; and (4) vermiculite was common throughout soils developed on plutonic rock fan deposits. These mineralogical differences suggest that minerals in the soils are primarily inherited from their parent materials and that mineral weathering in this area was weak. Except the abundance of palygorskite, soils developed on alluvial fans with different ages (4,000 to 200,000 yrs old) did not show other distinct mineralogy difference as a function of age or soil development, which supports the weak weathering of the soils. The results suggest that the clays in the argillic horizons are primarily derived from the accumulation of desert dust, and with time, are translocated into subsoil horizons. The pedogenic accumulation of dust is a soil-geomorphic process common to the Mojave Desert, as well as other deserts in the world.

  8. A discontinuity in the late Pleistocene alluvial deposits, Hwacheon-ri, Gyeongju, Korea: Occurrences and paleoenvironmental implications

    NASA Astrophysics Data System (ADS)

    Paik, In Sung; Kyeong Seol, Weon; Kim, Hyun Joo; Lee, Ho Il; Kang, Hee Cheol

    2015-04-01

    Sedimentary discontinuity surface occurs in the late Pleistocene alluvial deposits exposed along the cliff (about 10 m thick and over 140 m in length) in stream side, Gyeongju, Korea. The discontinuity surface is laterally extensive and marked by distinct carbonaceous dark horizon in the middle part of the deposits. The deposits are divided into lower and upper units by the discontinuity surface. The lower unit overlies unconformably the Cretaceous andesitic rock (basement), and consists of braided-river deposits. Lower part of the lower unit is mainly composed of lenticular-bedded and clast-supported conglomeratic deposits, whereas gray to dark gray sandy to muddy channel-plug deposits occur in the uppermost part of the lower unit. It is characteristic that iron-oxide crusts occur in the lower unit. They are cutting across the lower unit and truncated by the overlying upper unit. Rootlets mineralized by vivianite are present in the channel-plug deposits below the discontinuity surface. The upper unit overlying the lower unit with erosive contact (discontinuity surface) is mostly composed of matrix-supported conglomeratic alluvial fan deposits. Hornfelsic gravels are common in the lower unit, whereas andesitic gravels are predominant in the upper unit, suggesting the provenance change from the lower unit to the upper unit. OSL ages for the lower and the upper units are 125±9 ka and 94±9 ka, respectively, suggesting that the lower unit was deposited in MIS5e and the upper unit was formed in MIS5c to 5b. It is thus interpreted that the shift of depositional environment from a fluvial plain (lower unit) to an alluvial fan (upper unit) was an alluvial response to sea level change inducing fall of base level in an alluvial basin from the interglacial to the glacial stages. The development of iron-oxide crusts and diagenetic vivianite in the discontinuity surface suggest that humid condition persisted during the paleoclimatic shift from the last interglacial to the last glacial stages. Key words: Late Pleistocene, Alluvial deposits, Discontinuity, Iron-oxides, Vivianite

  9. Rock magnetic properties of a soil developed on an alluvial deposit at Buttermilk Creek, Texas, USA

    NASA Astrophysics Data System (ADS)

    Lindquist, Anna K.; Feinberg, Joshua M.; Waters, Michael R.

    2011-12-01

    The evolution of magnetization within a floodplain soil begins with initial deposition of magnetic particles during sedimentation and continues via subsequent alteration and growth of iron-bearing compounds by pedogenic and biologic processes. Measurements of soil magnetic properties capture information about the developmental history of the soil and are a convenient method by which to investigate environmental change and pedogenesis. Using a range of magnetic measurements, a comprehensive scenario for soil development was constructed for floodplain sediments at the Debra L. Friedkin site, an important archeological site near Buttermilk Creek, Texas. Floodplain deposits have traditionally been avoided for soil magnetism studies because it is thought that the episodic input of sediment would form soils characterized by discrete sedimentary units rather than a continuous record of pedogenesis. We demonstrate that alluvial deposits can sometimes carry a straightforwardly interpretable magnetic signal similar to those typically seen in loess deposits. Smooth variation of rock magnetic parameters as a function of depth also leads us to conclude that the soil at this site is largely undisturbed and that the age of lithic artifacts found within the soil may be interpreted within stratigraphic context.

  10. Origin and depositional model of Wadi Al-Batin and its associated alluvial fan, Saudi Arabia and Kuwait

    Microsoft Academic Search

    Jawad S. Al-Sulaimi; A. F. Pitty

    1995-01-01

    Wadi Al-Batin alluvial fan, which extends northeastward from Hafar Al-Batin in Saudi Arabia to cover parts of Kuwait and southwestern Iraq, represents the largest of several other non-active fans in central and south Arabia. Evidence put forward suggests that, like other comparable deposits of varying age in the Arabian Peninsula, the Al-Batin fan was deposited following downdip breaching of a

  11. An assessment of the contribution of fossil cave deposits to the Quaternary paleontological record

    Microsoft Academic Search

    Christopher N. Jass; Christian O. George

    2010-01-01

    Mammal-bearing cave deposits are an important part of the Quaternary fossil record, but the exact nature of the contribution that caves make to the fossil record is a research area that is largely unexplored. To explore this issue, late Pleistocene species representation in cave versuses non-cave deposits was examined. Additionally, this study examined how fossiliferous cave deposits influence perceptions of

  12. Aggradation and degradation of alluvial sand deposits, 1965 to 1986, Colorado River, Grand Canyon National Park, Arizona

    USGS Publications Warehouse

    Schmidt, J.C.; Graf, J.B.

    1988-01-01

    High discharges occurring between 1983-1985 resulted in redistribution of sand stored in zones of recirculating current in the Colorado River in Grand Canyon National Park. Redistribution resulted in net loss in the number of reattachment deposits in narrow reaches and aggradation of some separation deposits. Separation deposits were more stable than other types of deposits. Alluvial sand deposits that are large enough and of sufficient size for use as campsites were more stable than smaller lower-elevation deposits. Fluctuating flows between October 1985 and January 1986 caused erosion throughout the Grand Canyon, and caused erosion of some deposits created by the high flows of 1983-1985. Data collected for this study included measurements of flow velocity, scour-and-fill of sand deposits, topographic and bathymetric surveys, mapping of surface-flow patterns, water-surface slope surveys, sedimentological analysis, and replication of photographs. A classification system of alluvial sand deposits was developed on the basis of morphometric characteristics and the location of these deposits in relation to parts of recirculation zones. (Author 's abstract)

  13. Aggradation and degradation of alluvial sand deposits, 1965 to 1986, Colorado River, Grand Canyon National Park, Arizona

    USGS Publications Warehouse

    Schmidt, John C.; Graf, Julia B.

    1990-01-01

    Alluvial sand deposits along the Colorado River in Grand Canyon National Park are used as campsites and are substrate for vegetation. The largest and most numerous of these deposits are formed in zones of recirculating current that are created downstream from where the channel is constricted by debris fans at tributary mouths. Alluvial sand deposits are classified by location and form. Separation and reattachment deposits are downstream from constrictions within recirculation zones. Separation deposits are near the point of flow separation and typically mantle large debris fans. Reattachment deposits are near the point of flow reattachment and project upstream beneath much of the zone of recirculating current. Upper-pool deposits are upstream from a constriction and are associated with backwaters. Channel-margin deposits line the channel and have the form of terraces. Some are created in small recirculation zones. Reattachment and channel-margin deposits are largest and most numerous in wide reaches, although small channel-margin deposits are used as campsites in the narrow Muav Gorge. Separation deposits are more uniformly distributed throughout Grand Canyon National Park than are other types of deposits. In some narrow reaches where the number of alluvial sand deposits used as campsites is small, separation deposits are a high percentage of the total. During high flows, both separation and reattachment deposits are initially scoured but are subsequently redeposited during flow recession. Sand is also exchanged between the main channel and recirculation zones. The rate of recession of high flows can affect the elevation of alluvial deposits that are left exposed after a flood has passed. Fluctuating flows that follow a period of steady discharge cause initial erosion of separation and reattachment deposits. A part of this eroded sand is transported to the main channel. Therefore, sand is exchanged between the main channel and recirculation zones and redistributed within recirculation zones over a broad range of discharges. Comparison of aerial photographs and reinterpretation of published data concerning changes of alluvial sand deposits following recession of high flows in 1983 and 1984 indicate that sand was eroded from recirculation zones in narrow reaches. In wide reaches, however, aggradation in recirculation zones may have occurred. In narrow reaches, the decrease of reattachment deposits was greater than that of separation deposits. In all reaches, the percentage of separation deposits that maintained a constant area was greater than for other deposits. Separation deposits, therefore, appear to be the most stable of the deposit types. Fluctuating flows between October 1985 and January 1986, which followed the higher and steadier flows of 1983 to 1985, caused erosion throughout the park. For separation deposits, erosion was greatest at those sites where deposition from the 1983 high flows had been greatest. The existing pattern of low campsite availability in narrow reaches and high campsite availability in wide reaches was thus accentuated by the sequence of flows between 1983 and 1985.

  14. Hydrogeologic characteristics of the alluvial aquifer and adjacent deposits of the Fountain Creek valley, El Paso County, Colorado

    USGS Publications Warehouse

    Radell, Mary Jo; Lewis, Michael E.; Watts, Kenneth R.

    1994-01-01

    The alluvial aquifer in Fountain Creek Valley between Colorado Springs and Widefield is the source for several public-supply systems. Because of the importance of this aquifer, defining aquifer boundaries, areas where underflow occurs, and where Fountain Creek is hydraulically connected to the aquifer will greatly add to the understanding of the alluvial aquifer and management of the public- supply systems. Bedrock altitude, water-table altitude for October 1991, saturated thickness for October 1991, selected hydrogeologic sections in the alluvial aquifer and adjacent deposits of the Fountain Creek Valley, and estimated underflow rates are mapped or tabulated for the area between Colorado Springs and Widefield, Colorado. Results from test drilling indicate that the bedrock surface is highly irregular and that several ridges and buried channels exist in the study area. These features affect the direction of ground-water flow on a local scale. In places, a shale ridge prevents exchange of water between Fountain Creek and the aquifer. Generally, ground water flowed toward Fountain Creek during the study (June 1991 to September 1992) in response to relatively high hydraulic heads in the aquifer and the steep gradients on the boundaries of the study area. Water levels, which were measured monthly, varied little during the study, except in areas near pumping wells or adjacent to Fountain Creek. Hydraulic-conductivity values, estimated from 30 bail tests in wells completed in the alluvial aquifer, were used to determine underflow across the saturated boundaries of the alluvial aquifer. Estimated hydraulic-conductivity values range from 1 to about 1,300 feet per day; the larger values occur in the buried channel of the alluvial aquifer and the smaller values occur near the boundaries of the saturated alluvium. Estimated underflow into the study area exceeded underflow out of the study area by about 10 times. Gain-loss investigations along Fountain Creek indicated that the creek primarily was gaining during the study.

  15. Aggradation and degradation of alluvial sand deposits, 1965 to 1986, Colorado River, Grand Canyon National Park, Arizona; executive summary

    USGS Publications Warehouse

    Schmidt, J.C.; Graf, J.B.

    1988-01-01

    High discharges that occurred in 1983-85 resulted in redistribution of sand stored in zones of recirculating current in the Colorado River in Grand Canyon National Park. Redistribution resulted in net loss in the number of reattachment deposits in narrow reaches and aggradation of some separation deposits. Separation deposits were more stable than other types of deposits. Alluvial sand deposits that are large enough and of sufficient areal extent for use as campsites were more stable than smaller lower-elevation deposits. Fluctuating flows between October 1985 and January 1986 caused erosion throughout the Grand Canyon and caused erosion of some deposits created by the high flows of 1983-85. (Author 's abstract)

  16. Potential controls of alluvial bench deposition and erosion in southern Piedmont streams, Alabama (USA)

    NASA Astrophysics Data System (ADS)

    Haney, Nicholas R.; Davis, Lisa

    2015-07-01

    Benches are bank-attached channel deposits occurring at an elevation between the channel bed and top of banks. Their occurrence in a variety of geologic and hydrologic settings has led to confusion about the mechanisms driving their formation, which in turn contributes to difficulty identifying the active floodplain, bankfull stage, and the determination of environmental flows in some rivers. Hydrodynamic modeling software (River 2D), in combination with sediment particle size analysis and total station topographic surveys, was used to simulate flow conditions needed to erode and deposit the D84, D50, and D15 particle sizes of concave and lateral benches in two rivers (Talladega and Hillabee creeks) in Alabama. Results suggest that bench erosion requires flows at least 150% larger than benchfull stage at the Talladega site, while the Hillabee site experienced erosion at all discharges meeting and exceeding benchfull flow stage, likely owing to its overall smaller sediment particle sizes. At both sites, the presence of vegetation increased the bench area subjected to deposition but, somewhat counterintuitively, also helped influence the location of erosion by limiting flow vectors. In contrast with previous research findings, the occurrence of reverse flow was neither sustained nor widespread at either site. These findings provide new insight into alluvial benches, suggest that the study benches are relatively stable features under the prevailing hydrologic regime, and that in some temperate climate settings, such as the southern Piedmont, localized hydraulic controls on bench formation can be superseded in importance by hydrologic flow regime, even in the case of concave benches and where flow regulation is not a factor.

  17. Effect of the behavior and availability of heavy metals on the characteristics of the coastal soils developed from alluvial deposits

    Microsoft Academic Search

    Jinling Li; Ming He; Shouqin Sun; Wei Han; Youchi Zhang; Xiaohui Mao; Yifan Gu

    2009-01-01

    An investigation of the behavior and availability of heavy metals (HMs), i.e., Cu, Zn, Ni, Pb, Cr, and Cd, based on the analysis\\u000a of correlation between HMs and physical and chemical properties of coastal soils developed from alluvial deposits in Shanghai,\\u000a China, has been conducted, in order to reveal the effect of the soil formation and development and the unsuited

  18. High-resolution sequence stratigraphic analysis of Late Quaternary deposits of the Changhua Coastal Plain in the frontal arc-continent collision belt of Central Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, Hua-Wen; Lee, Tung-Yi; Wu, Leh-Chyun

    2010-08-01

    Detailed analysis of the sequence stratigraphy in 30 cores from the Late Quaternary deposits of the Changhua Coastal Plain provides a 25 ka record of the depositional history of a region situated in the frontal arc-continent collision belt of Taiwan. Twenty-five lithofacies and nine facies associations are recognized. An alluvial plain was the dominant feature during a pronounced sea-level fall at 25-20 ka ago. Between 20 and 10 ka, alluvial fans were deposited along the western front of the Pakua Tableland during movement along the Changhua Fault, and a local sag basin was produced. No other deposits in the seaward area are recognized between 20 and 16 ka, or in the landward area between 20 and 10 ka. Between 16 and 6 ka, the Changhua Coastal Plain experienced rising sea level and retrogradational deposition. From 16 to 10 ka, estuarine deposits (lower transgressive systems tract) were deposited, and the base of these deposits defines the Last Glacial Maximum (LGM) unconformity (sequence boundary), now preserved in four regions to the east of the plain. From 10 to 6 ka, shelf, shoreface, and lagoonal deposits (upper transgressive systems tract) were laid either on top of the estuarine deposits or directly on the LGM unconformity surface. By about 7-6 ka, sea level had reached its peak (maximum flooding surface), and shelf and marginal marine sediments covered most of the study area. After 6 ka, the highstand was dominated by progradation of offshore-transition, shoreface, lagoonal, tidal channel, tidal flat and alluvial plain deposits. One-thousand-year-old fluvial deposits in incised channels are preserved in the central part of the Changhua Coastal Plain. Since then, fluvial channels shifted southward to the present-day Chuoshuei River. The depositional patterns in this tectonically active area during the last interglacial period reflect the complex interplay between high-frequency sea-level fluctuations, tectonics (subsidence and uplift), and autocyclic processes. In the seaward area, however, fluctuations in sea level were clearly the dominant factor in controlling the nature of depositional facies.

  19. Arsenic Levels in Groundwater from Quaternary Alluvium in the Ganga Plain and the Bengal Basin, Indian Subcontinent: Insights into Influence of Stratigraphy

    Microsoft Academic Search

    S. K. Acharyya

    2005-01-01

    Late Quaternary stratigraphy and sedimentation in the Ganga Alluvial Plain and the Bengal Basin have influenced arsenic contamination of groundwater. Arsenic contaminated aquifers are pervasive within lowland organic rich, clayey deltaic sediments in the Bengal Basin and locally within similar facies in narrow, entrenched river valleys within the Ganga Alluvial Plain. These were mainly deposited during early-mid Holocene sea level

  20. Geotechnical characterization of the upper Pleistocene–Holocene alluvial deposits of Roma (Italy) by means of multivariate geostatistics: Cross-validation results

    Microsoft Academic Search

    Giuseppe Raspa; Massimiliano Moscatelli; Francesco Stigliano; Antonio Patera; Fabrizio Marconi; Daiane Folle; Roberto Vallone; Marco Mancini; Gian Paolo Cavinato; Salvatore Milli; João Felipe Coimbra Leite Costa

    2008-01-01

    We are presenting an attempt to evaluate the spatial variability of geotechnical parameters in the upper Pleistocene–Holocene alluvial deposits of Roma (Italy) by means of multivariate geostatistics.The upper Pleistocene–Holocene alluvial deposits of Roma are sensitive to high levels of geohazard. They occupy a sizable and significant part of the city, being the foundation for many monuments, historical neighborhoods, and archaeological

  1. Ground water in the alluvial deposits of Cottonwood Creek Basin, Oklahoma

    USGS Publications Warehouse

    Stacy, B.L.

    1960-01-01

    Cottonwood Creek basin is a 377 square mile area in central Oklahoma. The rim of the basin has altitudes as high as 1,300 feet, and the mouth is at an altitude of 910. Deposits of Quaternary age consist of alluvium along the stream courses and high terrace deposits along the southern rim of the basin. The alluvium contains a high percentage of clay and silt, ranges in thickness from a few inches to 40 feet, and underlies about 36 square miles of the basin. Sandstone, siltstone, and shale of Permian age, which form the bedrock, consist of the Garber sandstone along the eastern edge, the Hennessey shale through the central part, and Flowerpot shale along the western edge. Replenishment of water in the alluvium is from precipitation, lateral seepage and runoff from adjoining areas, and infiltration from the stream channels during high flows. The major use of ground water in the alluvium is transpiration by cottonwood and willow trees. Virtually no water is withdrawn from the alluvium by wells. (available as photostat copy only)

  2. Late Quaternary mass-wasting records and formation of alluvial terraces in the actively uplifting Lao-nong catchment, southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Tsui, H. K.; Hsieh, M. L.; Li, W. L.; Hsiao, Y. T.

    2014-12-01

    Although dominated by erosion over long term, the tectonically active mountains of Taiwan commonly contain thick landslide and debris-flow gravels capping hillslopes or forming alluvial terraces. These deposits and their associated landforms serve to study ancient mass-wasting histories and their controls on fluvial processes. This study focuses on the Lao-nong River draining the 1000-3000 m high mountain areas in southwestern Taiwan (current tectonic uplift: 10-20 mm/yr). The Lao-nong River exhibits numerous terraces, many of which are of tributary-fan origins and consist of fluvial/debris-flow gravels 20-200 m thick. The development of such alluvial terraces can be observed during 2009 Typhoon Morakot, which brought record-setting 2000 mm of rain. Triggered by this heavy rain, almost all the tributaries of the Lao-nong generated alluvial fans at their mouths and consequently caused up-to-30 m aggradation along the trunk river. The Lao-nong has yielded >100 radiocarbon dates (all <20 ka).These data reveal that the formation of the observed alluvial terraces (from deposition of thick gravels to subsequent incision) could proceed very rapidly (<1 ky), and that the trunk river has been characterized by repeated aggradation and incision. This fact highlights the significance of event-driven sediment supply in governing the river behavior, which has strongly obscured the effect of the concurrent tectonic uplift. Among the terraces consisting of thick gravels, the six with 100-200 m-thick gravels are dated~18ka, ~12ka (for two terraces), ~5.5ka, ~3.4ka, and ~1.4 ka. The seven terraces with 50-100 m-thick gravels are dated ~12ka, ~8.3ka, ~5.7ka, ~1.3ka and 0.2-1.6ka (two undated). These dates (and others) suggest the clusters of mass-wasting events around ~12ka, 5.5-5.7 ka, and <1.6 ka. However, note that most of the recorded mass-wasting events vary in time and magnitude among tributary catchments, which implies the controls of internal factors on the timing, magnitude, and frequency of the events. Our field observation suggests that at least some of the large Holocene tributary-fan terraces were sourced from pre-Holocene colluviums.

  3. Distinctive characteristics of a streamflow-dominated alluvial fan deposit: Sanghori area, Kyongsang Basin (Early Cretaceous), southeastern Korea

    NASA Astrophysics Data System (ADS)

    Jo, H. R.; Rhee, C. W.; Chough, S. K.

    1997-05-01

    In the northwestern part of the non-marine Kyongsang Basin (Early Cretaceous), conglomeratic deposits occur at intervals along the northern basin margin and grade basinward into interbedded sandstone and mudstone. One of these conglomeratic deposits, referred to as the Sanghori deposit, is 150 m thick and characterized by amalgamated sheets of conglomerate and sandstone (facies assemblages 1 and 2) alternating with interbedded sandstone and purple siltstone (facies assemblage 3). Facies assemblage 1 comprises clast-supported, disorganized and organized sheet conglomerates interbedded with massive to stratified sandstones. This assemblage is interpreted as the product of proximal gravel-bed stream deposition. Facies assemblage 2 consists of trough and planar cross-stratified and horizontally stratified sandstones. It represents sandy braided-stream deposits in which sand bars and dunes were common. Sedimentary facies and architecture of the coarse-grained facies assemblages suggest that the gravel-bed and sandy braided streams were wide and shallow, and rapidly aggraded during flash floods. Facies assemblage 3 consists of interbedded purple siltstone and tabular sandstone which show evidence of weak pedogenic modification and bioturbation. These characteristics are interpreted as the result of floodplain processes. Sediments were supplied from the north and dispersed radially, forming a streamflow-dominated alluvial-fan system. The Sanghori alluvial system was most probably fed from a large drainage basin, resulting in the predominance of streamflow deposits and rounded clasts. The alternation of the gravel-bed stream and floodplain deposits was due to autocyclic switching of active fan sectors under the conditions of relatively slow and steady basin subsidence.

  4. Relating lithofacies to hydrofacies: outcrop-based hydrogeological characterisation of Quaternary gravel deposits

    Microsoft Academic Search

    Ralf Klingbeil; Sybille Kleineidam; Ulrich Asprion; Thomas Aigner; Georg Teutsch

    1999-01-01

    A considerable part of today's drinking water supplies in Europe and North America rely on clean groundwater from gravelly valley aquifers of Quaternary age. The sedimentary architecture, the distribution of lithofacies and of architectural elements in such heterogeneous deposits are of fundamental importance for the analysis of groundwater flow and contaminant transport. As the aquifers are not directly accessible for

  5. Sequence stratigraphic interpretation methods for low-accommodation, alluvial depositional sequences: applications to reservoir characterization of Cut Bank field, Montana 

    E-print Network

    Ramazanova, Rahila

    2009-05-15

    . ............................................................................................... 78 xiv Page Figure 39. Conceptual framework for bounding surface development driven by cyclic base-level fluctuation. (1) Base-level fall leads to the development of a regional erosion surface with incised valleys, sequence boundary 1 (SB1.../aggradation and a wide, nonconfined alluvial plain leads to the preservation of isolated channels within mudstone-rich overbank deposits. (4) Renewed base-level fall causes the development of the next regional erosion surface (SB2), and so on (from MacDonald et...

  6. Mineralogical characteristics of the superlarge Quaternary bauxite deposits in Jingxi and Debao counties, western Guangxi, China

    NASA Astrophysics Data System (ADS)

    Liu, Xuefei; Wang, Qingfei; Zhang, Qizuan; Feng, Yuewen; Cai, Shuhui

    2012-06-01

    In recent decades, more than 0.5 billion tons of ores scattered in the Quaternary laterite in western Guangxi, China have been explored. The ores were derived from a bauxite horizon in Permian via physical break-up and re-sediment process. Utilizing various test methods, i.e., XRD, DTA, TG/DTG, SEM/EDS and EPMA, the mineralogical characteristics of the Quaternary bauxite ores in Jingxi and Debao counties were investigated. XRD was used together with TG/DTG to obtain relatively accurate ore mineral abundance. Diaspore is the major phase, whereas hematite, kaolinite, anatase, chamosite, gibbsite, goethite, illite and rutile are minor. Diaspore is characterized by a small particle size, low degrees of crystallinity and complex chemical composition. Both gibbsite and goethite have a varied particle size, and goethite crystals contain high Al substitution and Si. It is clarified that diaspore, chamosite and anatase were formed in a mildly reduced and alkaline depositional environment in Permian, while gibbsite, hematite, goethite and part kaolinite were precipitated from Al3+-, Si4+- and Fe3+-enriched solutions within an Quaternary oxidized environment. The ions Al3+, Si4+ and Fe3+ are mostly released from chamosite in its dissolution process. The different physicochemical conditions between the Permian depositional and the Quaternary weathering periods resulted in a complex mineral assemblage in the Quaternary bauxite.

  7. Palaeoenvironmental reconstruction of a middle Miocene alluvial fan to cyclic shallow lacustrine depositional system

    E-print Network

    Utrecht, Universiteit

    margin facies, which show two distinct lithofacies associations depending on their distribution relative to the alluvial fan system, i.e. front (lithofacies A), comprising massive siliciclastic mudstone and tabular carbonates, or lateral (lithofacies B) showing laminated and/or massive siliciclastic mudstone alternating

  8. Stratigraphical and palynological appraisal of the Late Quaternary mangrove deposits of the west coast of India

    Microsoft Academic Search

    K. P. N. Kumaran; K. M. Nair; Mahesh Shindikar; Ruta B. Limaye; D. Padmalal

    2005-01-01

    The organic deposits derived from the mangrove swamps form reliable stratigraphic markers within the Late Quaternary sequence of Kerala–Konkan Basin. Three generations of such deposits have been identified. The older one is dated to around 43,000–40,000 14C yr B.P., with a few dates beyond the range of radiocarbon. The younger ones date from the Middle Holocene to latest Pleistocene (10,760–4540

  9. Stratigraphy and Subaerial Exposure of Late Quaternary Tidal Deposits in Haenam Bay, Korea (South-eastern Yellow Sea)

    Microsoft Academic Search

    Y. A. Park; D. I. Lim; B. K. Khim; J. Y. Choi; S. J. Doh

    1998-01-01

    Late Quaternary stratigraphy of the coastal deposits in Haenam Bay, south-western coast of Korea (south-eastern Yellow Sea) consists of two depositional units: a Holocene intertidal deposit (Unit I), and an underlying Late Pleistocene tidal deposit (Unit II), both of which are distinguished by distinct unconformity. The yellowish colour and more consolidated and oxidized nature are characteristics of the sediments in

  10. A refined characterization of the alluvial geology of yucca flat and its effect on bulk hydraulic conductivity

    USGS Publications Warehouse

    Phelps, G.A.; Halford, K.J.

    2011-01-01

    In Yucca Flat, on the Nevada National Security Site in southern Nevada, the migration of radionuclides from tests located in the alluvial deposits into the Paleozoic carbonate aquifer involves passage through a thick, heterogeneous section of late Tertiary and Quaternary alluvial sediments. An understanding of the lateral and vertical changes in the material properties of the alluvial sediments will aid in the further development of the hydrogeologic framework and the delineation of hydrostratigraphic units and hydraulic properties required for simulating groundwater flow in the Yucca Flat area. Previously published geologic models for the alluvial sediments within Yucca Flat are based on extensive examination and categorization of drill-hole data, combined with a simple, data-driven interpolation scheme. The U.S. Geological Survey, in collaboration with Stanford University, is researching improvements to the modeling of the alluvial section, incorporating prior knowledge of geologic structure into the interpolation method and estimating the uncertainty of the modeled hydrogeologic units.

  11. Late Quaternary eolian dust in surficial deposits of a Colorado Plateau grassland: Controls on distribution and ecologic effects

    E-print Network

    Ahmad, Sajjad

    Late Quaternary eolian dust in surficial deposits of a Colorado Plateau grassland: Controls-arid grassland on the central Colorado Plateau, southwestern United States (Fig. 1). The current work builds

  12. Origin and depositional model of Wadi Al-Batin and its associated alluvial fan, Saudi Arabia and Kuwait

    NASA Astrophysics Data System (ADS)

    Al-Sulaimi, Jawad S.; Pitty, A. F.

    1995-07-01

    Wadi Al-Batin alluvial fan, which extends northeastward from Hafar Al-Batin in Saudi Arabia to cover parts of Kuwait and southwestern Iraq, represents the largest of several other non-active fans in central and south Arabia. Evidence put forward suggests that, like other comparable deposits of varying age in the Arabian Peninsula, the Al-Batin fan was deposited following downdip breaching of a scarp barrier by a large paleoriver further to the west which once flowed southward down the full length of the Arabian Peninsula. The downdip breaching model offers an explanation of how the Dibdibba gravels were introduced into Kuwait. It is postulated that the present southeasterly course of Tigris-Euphrates rivers to the head of the Arabian Gulf was the last of the easterly diversions of the lower courses of the southward-flowing paleoriver, as its southern end shifted progressively by a sequence of lateral breaches through the Central Arabian scarplands. It is the postulated existence of this huge former drainage system which is seen as the fundamental explanation for the occurrence of the Dibdibba Formation in Kuwait and comparable gravels elsewhere on the eastern flank of the Arabian Peninsula. After the initial phases of deposition of Al-Batin alluvial fan, its surface was dissected by floods from a reduced catchment area, no longer carrying the same sediment load and, therefore, capable of eroding the fan. Dissection of the fan surface continued until the present Wadi AI-Batin became sufficiently incised into the underlying Tertiary bedrock to serve as a permanent outlet. This led to the transport and secondary concentration of post-dissection gravels along the perimeter of the ancient fan.

  13. Subsurface geology of upper Tertiary and Quaternary deposits, coastal Louisiana and adjacent Continental Shelf

    SciTech Connect

    McFarlan, E. Jr.; Leroy, D.O.

    1988-09-01

    Upper Tertiary and Quaternary deposits thicken seaward from a feather edge on the outcrop in the uplands of southern Louisiana to more than 7000 ft (2134 m) beneath the middle continental shelf. Through a study of cores and cuttings from 100 control wells and electric-log pattern correlations from 350 water and petroleum industry wells with seismic corroboration in the offshore area, these deposits have been divided into six major time-stratigraphic units, four of which correlate to outcropping terraces. This investigation presents a regional stratigraphic framework of the major upper Tertiary and Quaternary units from their updip pinch-outs in and beneath the terraced uplands, into the subsurface, across the coastal plain to the Louisiana offshore area.

  14. Pedogenic and early diagenetic processes in Palaeogene alluvial fan and lacustrine deposits from the Sado Basin (S Portugal)

    NASA Astrophysics Data System (ADS)

    Pimentel, N. L. V.

    2002-04-01

    The Palaeogene deposits of the Sado Basin were deposited in a continental basin that shows a typical pattern with alluvial fans system in the margins of the basin, passing towards distal areas of mudflat facies where, in some areas, the installation of shallow water bodies favoured the development of palustrine conditions. The deposits of this basin vary form coarse conglomerates and sandstones to palustrine carbonates. These sediments were affected by pedogenesis and early diagenetic processes that promoted important modifications on their primary features. These modifications have been studied by the analyses of four profiles, developed on proximal, middle and distal fan deposits and the fourth one on lacustrine deposits. The overall analyses of the sedimentological, pedogenic, diagenetic features and their relationships indicate that three main processes took place throughout the basin: soil formation, palygorskite neoformation and dolomitization. Soil formation processes led to illuviation of clays and carbonate precipitation mostly around roots. Pedogenic carbonates increase towards distal areas, whereas hydromorphic features are present throughout the basin. Palygorskite neoformation was partially diagenetic, being maximum in proximal areas and palustrine deposits. This neoformation is attributed to the percolation of alkaline Mg-rich soil and groundwaters through smectitic-rich sediments, promoting important clay transformation. Dolomitization was an early diagenetic process that occurred mainly in carbonate-rich deposits of distal and lacustrine environments, as a result of the increasing Mg/Ca ratio of the percolating groundwaters. In all these processes there has been a close spatial and temporal interplay between pedogenesis and diagenesis, driven by the chemistry of soil particles and groundwaters.

  15. Comparison of high-resolution P- and SH-wave reflection seismic data in alluvial and pyroclastic deposits in Indonesia

    NASA Astrophysics Data System (ADS)

    Wiyono, Wiyono; Polom, Ulrich; Krawczyk, Charlotte M.

    2013-04-01

    Seismic reflection is one of the stable methods to investigate subsurface conditions. However, there are still many unresolved issues, especially for areas with specific and complex geological environments. Here, each location has an own characteristic due to material compounds and the geological structure. We acquired high-resolution, P-and SH-wave seismic reflection profiles at two different locations in Indonesia. The first location was in Semarang (Central Java) and the second one was in Tiris (East Java). The first region is located on an alluvial plain with thick alluvial deposits of more than 100 m estimated thickness, and the second location was located on pyroclastic deposit material. The seismic measurements for both locations were carried out using a 48-channel recording system (14-Hz P-wave, 10-Hz SH-wave geophones) with geophone intervals of 5 m (P-waves) and 1 m (SH-waves), respectively. The seismic source for the P-wave was a ca. 4 kg sledge hammer which generated a seismic signal by by hitting on an aluminum plate of 30x30 cm, whereas the SH-wave source was a mini-vibrator ELVIS (Electrodynamic Vibrator System), version 3. Thirteen seismic profiles at Semarang and eighth profiles at Tiris were acquired. The results of seismic data in Semarang show fair to good seismic records for both P-and SH-waves. The raw data contain high signal-to-noise-ratio. Many clear reflectors can be detected. The P-wave data shows reflectors down to 250 ms two-way time while the SH-wave records show seismic events up to 600 ms two-way time. This result is in strong contrast to the seismic data result from the Tiris region. The P-wave data show very low signal to noise ratio, there is no reflection signal visible, only the surface waves and the ambient noise from the surrounding area are visible. The SH-waves give a fair to good result which enables reflector detection down to 300 ms two-way time. The results from the two seismic campaigns show that SH-wave reflection seismic seems to be the suitable method, which could be applied in Indonesia mainly in both alluvial and pyroclastic regions. In contrast, P-wave energy in the pyroclastic area is strongly attenuated and scattered within the uppermost layer. This prevented that the P-wave seismic signal reaches deeper reflectors, and therefore seismic P-wave records contain only noise from surface waves and ambient noise from the surrounding area, without any reflection signal.

  16. Saline-water contamination in Quaternary deposits and the Poplar River, East Poplar Oil Field, northeastern Montana

    USGS Publications Warehouse

    Thamke, J.N.; Craigg, S.D.

    1997-01-01

    The extent of saline-water contamination in Quaternary deposits in and near the East Poplar oil field may be as much as 12.4 square miles and appears to be present throughout the entire saturated zone. The saline-water contamination affects 9-60 billion gallons of ground water. Saline- contaminated water moves westward through Quaternary glacial deposits and merges with southward-flowing water in Quaternary alluvium in the Poplar River valley. Saline ground water discharges into the Poplar River, and increases the dissolved-solids and chloride concentrations of the river. The probable source of saline-water contamination in the Quaternary deposits is brine that is a byproduct of the production of crude oil in the East Poplar oil field study area.

  17. A silicified bird from Quaternary hot spring deposits

    PubMed Central

    Channing, Alan; Schweitzer, Mary Higby; Horner, John R; McEneaney, Terry

    2005-01-01

    The first avian fossil recovered from high-temperature hot spring deposits is a three-dimensional external body mould of an American coot (Fulica americana) from Holocene sinters of Yellowstone National Park, Wyoming, USA. Silica encrustation of the carcass, feathers and colonizing microbial communities occurred within days of death and before substantial soft tissue degradation, allowing preservation of gross body morphology, which is usually lost under other fossilization regimes. We hypothesize that the increased rate and extent of opal-A deposition, facilitated by either passive or active microbial mediation following carcass colonization, is required for exceptional preservation of relatively large, fleshy carcasses or soft-bodied organisms by mineral precipitate mould formation. We suggest physico-chemical parameters conducive to similar preservation in other vertebrate specimens, plus distinctive sinter macrofabric markers of hot spring subenvironments where these parameters are met. PMID:16024344

  18. Quaternary silicic pyroclastic deposits of Atitlán Caldera, Guatemala

    USGS Publications Warehouse

    Rose, William I., Jr.; Newhall, Christopher G.; Bornhorst, Theodore J.; Self, Stephen

    1987-01-01

    Atitlán caldera has been the site of several silicic eruptions within the last 150,000 years, following a period of basalt/andesite volcanism. The silicic volcanism began with 5–10 km3 of rhyodacites, erupted as plinian fall and pyroclastic flows, about 126,000 yr. B.P. At 85,000 yr. B.P. 270–280 km3 of compositionally distinct rhyolite was erupted in the Los Chocoyos event which produced widely dispersed, plinian fall deposits and widespread, mobile pyroclastic flows. In the latter parts of this eruption rhyodacite and minor dacite were erupted which compositionally resembled the earliest silicic magmas of the Atitlán center. As a result of this major eruption, the modern Atitlán (III) caldera formed. Following this event, rhyodacites were again erupted in smaller (5–13 km3) volumes, partly through the lake, and mafic volcanism resumed, forming three composite volcanoes within the caldera. The bimodal mafic/silicic Atitlán volcanism is similar to that which has occurred elsewhere in the Guatemalan Highlands, but is significantly more voluminous. Mafic lavas are thought to originate in the mantle, but rise, intrude and underplate the lower crust and partly escape to the surface. Eventually, silicic melts form in the crust, possibly partly derived from underplated basaltic material, rise, crystallize and erupt. The renewed mafic volcanism could reflect either regional magmato-tectonic adjustment after the large silicic eruption or the onset of a new cycle.

  19. Gypsum karstification induced subsidence: effects on alluvial systems and derived geohazards (Calatayud Graben, Iberian Range, Spain)

    Microsoft Academic Search

    Francisco Gutiérrez

    1996-01-01

    The karstification of the tertiary gypsum formations in the Calatayud Graben has given rise to synsedimentary and postsedimentary subsidence phenomena in both the Neogene sediments of the endorheic graben fill and in the Quaternary alluvial sediments deposited under exorheic conditions. In the so-called Maluenda and Perejiles areas, covering 4.4 and 12 km2 respectively, the Neogene sedimentary units stratigraphically above the

  20. Plio-Quaternary Seismic Stratigraphy and Depositional History at the Southern Exit of the Bosphorus Strait

    NASA Astrophysics Data System (ADS)

    Köprülü, Kerem; Vardar, Denizhan; Alpar, Bedri

    2015-04-01

    Analysis of Chirp seismic reflection data from the junction of the southern Bosphorus exit with the northern shelf of the Sea of Marmara reveal that Plio-Quaternary section in the area consists of three stacked sedimentary units separated by erosional unconformities. The seismic facies distribution suggests that deposition of Plio-Quaternary section in the studied area was controlled mainly by the hydrodynamic conditions which controlled the water exchange through the Bosphorus channel between the Black Sea and the Sea of Marmara, the sea-level fluctuations and partly by the tectonic movement as controlled by the North Anatolian fault. The main seismic sequences defined above the acoustic basement are made up of various sub-units with different seismic characteristic features. The deepest sequence (marine Unit 3), for example, is deposited under the control of the paleo-topography of the basement rocks. The overlying sub-unit (Unit 2a) is only observed in the natural paleo-canyon at the southern exit of the Bosphorus strait. Based on their reflection characteristics, its detrital material was supplied by a nearby river to the east during high-stand system tracts. Above the sub-unit 2a, a cut-and-fill structure forms the sub-unit 2b. It is small in size and caused locally by possible erosion of a northerly flow from the paleo-Bosphorus channel. At the top of these units, the parasequences of Unit 1 are transgressive marine deposits. The depositional energy, however, was relatively low at the beginning of these transgressive system tracts (sub-unit 1c) when the Black Sea flow into the study area was relatively weak. The ascending trajectory sigmoidal deposition of sub-unit 1b indicates the increment flow of Black Sea into the Sea of Marmara. The studied area was then invaded by the Mediterranean water. The sub-unit 1a is deposited under present oceanographic conditions.

  1. Seismogenic structures in Quaternary lacustrine deposits of Lake Van (eastern Turkey)

    NASA Astrophysics Data System (ADS)

    Üner, Serkan

    2014-07-01

    Soft-sediment deformation structures formed by liquefaction and/or fluidisation of unconsolidated sediments due to seismic shocks are frequent in the Quaternary sandy, silty and clayey deposits of Lake Van. They are present in both marginal and deep lacustrine facies. Their morphology and interpreted genesis imply that they should be considered as fluid-escape structures (dish and pillar structures, flame structures and sand volcanoes), contorted structures (simple and complex convolutions and ball-and-pillow structures) and other structures (disturbed layers and slump structures). The most recently formed structures are related to the October 23rd, 2011 Van-Tabanli (M 7.2) earthquake. The existence of seismites at various stratigraphic levels in the lacustrine deposits is indicative of tectonic activity that frequently triggered earthquakes with magnitudes of 5 or more, affecting the Lake Van Basin.

  2. Late Pleistocene landscape response to climate change: eolian and alluvial fan deposition, Cape Liptrap, southeastern Australia

    Microsoft Academic Search

    Thomas W. Gardner; John Webb; Aaron G. Davis; Elizabeth J. Cassel; Claudia Pezzia; Dorothy J. Merritts; Barton Smith

    2006-01-01

    Sea cliffs along the western coast of Cape Liptrap at Arch Rock provide nearly continuous exposure of calcareous eolianites dated at 68–112ka (five optically stimulated luminescence (OSL) ages). Calcareous eolian deposition began immediately after the last interglacial marine highstand (Oxygen Isotope Stage (OIS) 5e) and continued during sea level fall until the beginning of OIS 4. West-southwesterly winds transported calcareous

  3. Late quaternary history and uranium isotopic compositions of ground water discharge deposits, Crater Flat, Nevada

    USGS Publications Warehouse

    Paces, James B.; Taylor, Emily M.; Bush, Charles

    1993-01-01

    Three carbonate-rich spring deposits are present near the southern end of Crater Flat, NV, approximately 18 km southwest of the potential high-level waste repository at Yucca Mountain. We have analyzed five samples of carbonate-rich material from two of the deposits for U and Th isotopic compositions. Resulting U-series disequilibrium ages indicate that springs were active at 18 ?? 1, 30 ?? 3, 45 ?? 4 and >70 ka. These ages are consistent with a crude internal stratigraphy at one site. Identical ages for two samples at two separate sites suggest that springs were contemporaneous, at least in part, and were most likely part of the same hydrodynamic system. In addition, initial U isotopic compositions range from 2.8 to 3.8 and strongly suggest that ground water from the regional Tertiary-volcanic aquifer provided the source for these hydrogenic deposits. This interpretation, along with water level data from near-by wells suggest that the water table rose approximately 80 to 115 m above present levels during the late Quaternary and may have fluctuated repeatedly. Current data are insufficient to allow reconstruction of a detailed depositional history, however geochronological data are in good agreement with other paleoclimatic proxy records preserved throughout the region. Since these deposits are down gradient from the potential repository site, the possibility of higher ground water levels in the future dramatically shortens both vertical and lateral ground water pathways and reduces travel times of transported radionuclides to potential discharge sites.

  4. Depositional character of a dry-climate alluvial fan system from Palaeoproterozoic rift setting using facies architecture and palaeohydraulics: Example from the Par Formation, Gwalior Group, central India

    NASA Astrophysics Data System (ADS)

    Chakraborty, Partha Pratim; Paul, Pritam

    2014-09-01

    The ?20 m thick coarse-grained clastic succession in the basal part of Palaeoproterozoic Par Formation, Gwalior Group has been investigated using process-based sedimentology and deductive palaeohydraulics. Bounded between granitic basement at its base and shallow marine succession at the top, the studied stratigraphic interval represents products of an alluvial fan and its strike-wise co-existent braided river system that possibly acted as a tributary for the fan. Detailed facies, facies association analysis allowed identification of two anatomical parts for the fan system viz. proximal and mid fan. While thin proximal fan is represented by products of rock avalanche and hyperconcentrated flows with widely varying rheology, the mid fan is represented by products of sheet floods and flows within streamlets. The interpretation found support from palaeoslope estimation carried out on the fluvial part of the mid fan that plot dominantly within the alluvial fan field demarcated by Blair and McPherson (1994). Dry climatic condition suggested from dominance of stream flow over mass flow deposition within the Par alluvial fan. Strike-wise, the fan is discontinuous and juxtaposed with a braid plain system. In contrast to the fluvial part of fan system, the palaeoslope data from the braid plain system dominantly plot within the ‘natural depositional gap' defined by Blair and McPherson. A raised palaeoslope for the river systems, as suggested from Proterozoic braid plain deposits around the Globe, is found valid for the Par braid plain system as well. From preponderance of granular and sandy sediments within the alluvial fan and braid plain systems and a pervasive north-westward palaeocurrent pattern within the fluvial systems the present study infers a gently sloping bevelled source area in the south-southeast of the basin with occurrence of steep cliffs only locally.

  5. Evolution of the late Holocene terraces in the hanging wall of the Chihshang Fault: interactions between alluvial fan deposition and fault uplift

    NASA Astrophysics Data System (ADS)

    Chang, Q.; Lee, J.; Wang, S.; Chen, R.; Chen, Y.

    2012-12-01

    In this study, we aim at studying the interactions between alluvial fan deposition and reverse fault uplift through analyzing the genesis of the terraces and their evolution in Chihshang area. Located in eastern Taiwan, the NNE-SSW trending Longitudinal Valley is the plate suture between the Philippine Sea plate and Eurasia. The east-dipping Longitudinal Valley Fault (LVF), often on the eastern side of the valley, is the major fault of this suture zone. The Chihshang area is located in the central-southern Longitudinal Valley, where the Chihshang Fault cuts through the eastern edge of the Xinwulyu River alluvial fan, one of the major alluvial fans. The Chihshang Fault is one of the most active segments of the LVF with a continuous uplifting rate up to ~3 cm/yr. A series of fan terraces with different height distribute on the hanging wall, where the front of the alluvial fan was uplifted by the reverse fault. Because of the special geological settings of this area, by studying the evolution of the terraces we could get insights on both the deposition behavior of the alluvial fan and the long term uplift rate of Chihshang Fault, and furthermore, their interactions through the late Holocene. We used 5-m high-resolution DEM and aerial photographs to identify the terraces and characterize their geomorphic features. We also distinguished the Xinwulyu River alluvial fan terraces from other terraces formed by other tributary rivers based on the lithology of terrace deposit as well as the geomorphic characters. Several outcrops and six trenches of 3-6 m depth allow us to analyze the composition of the fan terraces and to collect dating materials. Fan terraces are distinguished into ten levels according to height difference relative to the present fan surface. Terraces belonging to same level were assumed to form at similar time period. The lower the terraces, the better the terraces preservation, and the larger the terraces surface area. Distribution of terrace is not geographically uniform: higher levels (T5-T9) and the lowest level (T1) are mainly found on northern part, while medium levels (T2-T4) can only be found on southern part. Assuming that the long-term fault uplifting is a nearly continuous creeping process, the genesis of terraces should have also been influenced by the periodic deposition process of alluvial fan. Each level of terraces represents a major deposition episode of the Xinwulyu River. These deposition episodes might indicate period with larger river sediment flux. However, each deposition episode might not have the same influenced area, which caused the different fan terraces character in different areas. Most of the terraces are found to have secondary deposits covering over the fluvial gravels. The thickest is found on one T5 terrace, which is composed of homogeneous fine-grain sediments and with thickness up to five meters. The source is hard to tell from the field observation, but the radiocarbon dating results of the datable materials (most are charcoals) found a reverse time-series in the ages of around 9,000-40,000 BP cal., which implies the steady erosion and redeposition process from an old pre-existing terrace. These results allow us to reconstruct the evolution of the terraces, and the mechanisms behind it.

  6. A methodological toolkit for field assessments of artisanally mined alluvial diamond deposits

    USGS Publications Warehouse

    Chirico, Peter G.; Malpeli, Katherine C.

    2014-01-01

    This toolkit provides a standardized checklist of critical issues relevant to artisanal mining-related field research. An integrated sociophysical geographic approach to collecting data at artisanal mine sites is outlined. The implementation and results of a multistakeholder approach to data collection, carried out in the assessment of Guinea’s artisanally mined diamond deposits, also are summarized. This toolkit, based on recent and successful field campaigns in West Africa, has been developed as a reference document to assist other government agencies or organizations in collecting the data necessary for artisanal diamond mining or similar natural resource assessments.

  7. Hydraulic and field water-chemistry characteristics of piedmont alluvial deposits in the Middle Tyger River near Lyman, Spartanburg County, South Carolina, 2005

    USGS Publications Warehouse

    Harrelson, Larry G.; Addison, Adrian D.

    2006-01-01

    This study explores the possibility of developing a bank-filtration process to improve water quality in which alluvial deposits serve as a natural sand filter to pretreat water to be used as a secondary drinking-water source in a small piedmont reservoir along the Middle Tyger River near Lyman in Spartanburg County, South Carolina. From January 2004 to September 2005, data from 10 auger borings, 2 sediment cores, 29 ground-penetrating radar transects, and 3 temporary observation wells, and field water-chemistry data were collected and analyzed. These data were collected and used to characterize the lithology, geometry, hydraulic properties, yield potential, and water-chemistry characteristics of the alluvial deposits in the channel and on the right bank of the reservoir. The assessment was undertaken to determine if an adequate amount of water could be withdrawn from the alluvial deposits to sustain a bank-filtration process and to characterize the water chemistry of the surface water and pore water. The heterogeneous alluvial and fill material at the study site--clay, silty clay, clayey sand, fine- to coarse-grained sand, and mica--on the right bank of the Middle Tyger River ranges in thickness from 0.6 to 7 meters, has a calculated horizontal hydraulic conductivity of 1 meter per day, and yields approximately 0.07 liter per second of water. The small calculated horizontal hydraulic conductivity and water yield for these deposits restrict the use of the right bank as a potential bank-filtration site. The coarse-grained alluvial sand deposit in the channel of the Middle Tyger River, however, may be used for a limited bank-filtration process. The discharge during pumping of the channel deposit yielded water at the rate of 1.9 liters per second. The coarse-grained channel deposit is approximately 49 meters wide and 3 meters thick near the dam. At approximately 183 meters upstream from the dam, the channel narrows to roughly 9 meters and the channel deposits thin to approximately 0.1 meter. Slug tests conducted in the channel deposits near the dam produced a calculated horizontal hydraulic conductivity of 60 meters per day. The limited thickness and aerial extent of the coarse-grained channel deposits coupled with large horizontal hydraulic conductivity likely would allow rapid transmission of water and may degrade the effectiveness of some water-chemistry improvements typical of a bank-filtration process. Field water-chemistry data were collected for approximately 1 hour and 45 minutes at 10 to 15 minute intervals to compare the surface-water and pore-water quality in and beneath the channel of the Middle Tyger River. The waterchemistry data indicate that (1) the mean water temperature was higher in surface water (22.5 degrees Celsius) than in pore water (18.5 degrees Celsius), (2) the mean specific conductance was less in surface water (56.9 microsiemens per centimeter at 25 degrees Celsius) than in pore water (125.7 microsiemens per centimeter at 25 degrees Celsius), (3) alkalinity was lower in surface water (22.5 milligrams per liter) than in pore water (44.6 milligrams per liter), and (4) recorded pH values ranged between 6.2 and 6.3 in the surface water and pore water during the sampling period. The flow velocity was orders of magnitude slower in the pore water than in the surface water; therefore, the pore water interacts with the alluvial sediment for a longer period of time producing the variation in water-chemistry data between the two waters.

  8. Maps of Quaternary Deposits and Liquefaction Susceptibility in the Central San Francisco Bay Region, California

    USGS Publications Warehouse

    Witter, Robert C.; Knudsen, Keith L.; Sowers, Janet M.; Wentworth, Carl M.; Koehler, Richard D.; Randolph, Carolyn E.; Brooks, Suzanna K.; Gans, Kathleen D.

    2006-01-01

    This report presents a map and database of Quaternary deposits and liquefaction susceptibility for the urban core of the San Francisco Bay region. It supercedes the equivalent area of U.S. Geological Survey Open-File Report 00-444 (Knudsen and others, 2000), which covers the larger 9-county San Francisco Bay region. The report consists of (1) a spatial database, (2) two small-scale colored maps (Quaternary deposits and liquefaction susceptibility), (3) a text describing the Quaternary map and liquefaction interpretation (part 3), and (4) a text introducing the report and describing the database (part 1). All parts of the report are digital; part 1 describes the database and digital files and how to obtain them by downloading across the internet. The nine counties surrounding San Francisco Bay straddle the San Andreas fault system, which exposes the region to serious earthquake hazard (Working Group on California Earthquake Probabilities, 1999). Much of the land adjacent to the Bay and the major rivers and streams is underlain by unconsolidated deposits that are particularly vulnerable to earthquake shaking and liquefaction of water-saturated granular sediment. This new map provides a consistent detailed treatment of the central part of the 9-county region in which much of the mapping of Open-File Report 00-444 was either at smaller (less detailed) scale or represented only preliminary revision of earlier work. Like Open-File Report 00-444, the current mapping uses geomorphic expression, pedogenic soils, inferred depositional environments, and geologic age to define and distinguish the map units. Further scrutiny of the factors controlling liquefaction susceptibility has led to some changes relative to Open-File Report 00-444: particularly the reclassification of San Francisco Bay mud (Qhbm) to have only MODERATE susceptibility and the rating of artificial fills according to the Quaternary map units inferred to underlie them (other than dams - adf). The two colored maps provide a regional summary of the new mapping at a scale of 1:200,000, a scale that is sufficient to show the general distribution and relationships of the map units but not to distinguish the more detailed elements that are present in the database. The report is the product of cooperative work by the National Earthquake Hazards Reduction Program (NEHRP) and National Cooperative Geologic Mapping Program of the U.S. Geological Survey, William Lettis and & Associates, Inc. (WLA), and the California Geological Survey. An earlier version was submitted to the U.S. Geological Survey by WLA as a final report for a NEHRP grant (Witter and others, 2005). The mapping has been carried out by WLA geologists under contract to the NEHRP Earthquake Program (Grant 99-HQ-GR-0095) and by the California Geological Survey.

  9. Models of deposition of loess and loessoids in the upper quaternary of South America

    NASA Astrophysics Data System (ADS)

    Iriondo, Martín H.

    1997-01-01

    Climatic changes occurred in South America during the Quaternary provoked deflation and deposition of large masses of silt, which formed loess and loessoid units of regional extension in several areas of the continent. An analysis of the most important Late Pleistocene and Holocene loess and loess-like deposits resulted in the identification of five types of transport and deposition of wind-blown silt. They are: 1) Pampa type — Winds derived from the Patagonian ice field during the LGM transported to the NE silt and fine sand formed by frost action in the Cordillera, forming a large sand sea and a loess belt behind it. 2) Chaco type — During the LGM, minor temporary streams transported frost-originated silt from the Cordillera to the low-lands in south Bolivia and NW Argentina. Dry tropical north winds deflated the sediment to the south, forming a valley-and-plain loess deposit. 3) Originated in subtropical anticyclones — During the Upper Holocene, a stational anticyclonic center produced semiarid climatic conditions and dry winds in the Argentine plains and surrounding regions, eroding the Pleistocene loess and sedimenting a thin loess carpet and several sand fields over an area of 1,600,000 km 2. 4) Originated in trade-winds — In the Llanos del Orinoco (Colombia and Venezuela) the NE trade winds deposited a sand and loess mantle during the dry late Pleistocene. Sediments came from the Guayana Shield and from the coastal plain. 5) Volcanic loessoids — Several loess-like sediment sheets, composed of partially altered volcanic ash, cover the Interandean Valley in north Ecuador.

  10. Subsurface geology of the late Tertiary and Quaternary water-bearing deposits of the southern part of the San Joaquin Valley, California

    USGS Publications Warehouse

    Croft, M.G.

    1972-01-01

    The study area, which includes about 5,000 square miles of the southern part of the San Joaquin Valley, is a broad structural trough of mostly interior drainage. The Sierra Nevada on the east is composed of consolidated igneous and metamorphic rocks of pre-Tertiary age. The surface of these rocks slopes 4?-6? southwestward from the foothills and underlies the valley. The Coast Ranges on the west consist mostly of complexly folded and faulted consolidated marine and nonmarine sedimentary rocks of Jurassic, Cretaceous, and Tertiary age, which dip eastward and overlie the basement complex. Unconsolidated deposits, of late Pliocene to Holocene age, blanket the underlying consolidated rocks in the valley and are the source of most of the fresh ground water. The unconsolidated deposits, the subject of this report, are divided into informal stratigraphic units on the basis of source of sediment, environment of deposition, and texture. Flood-basin, lacustrine, and marsh deposits are fine grained and underlie the valley trough. They range in age from late Pliocene to Holocene. These deposits, consisting of nearly impermeable gypsiferous fine sand, silt, and clay, are more than 3,000 feet thick beneath parts of Tulare Lake bed. In other parts of the trough, flood-basin, lacustrine, and marsh deposits branch into clayey or silty clay tongues designated by the letter symbols A to F. Three of these tongues, the E, C, and A clays, lie beneath large areas of the southern part of the valley. The E clay includes the Corcoran Clay Member of the Tulare Formation, the most extensive hydrologic confining layer in the valley. The E clay underlies about 3,500 square miles of bottom land and western slopes. The beds generally are dark-greenish-gray mostly diatomaceous silty clay of Pleistocene age. Marginally, the unit bifurcates into an upper and a lower stratum that contains thin beds of moderately yellowish-brown silt and sand. The E clay is warped into broad, gentle northwesterly trending anticlines and synclines. The C clay, of Pleistocene age, is a fine-grained lacustrine or paludal deposit occurring 220-300 feet beneath Tulare Lake bed and parts of Fresno Slough. The beds consist of bluish-gray silty clay. Structural contours indicate that the C clay has been extensively warped and folded. The A clay of Pleistocene and Holocene (?) age is a fine-grained lacustrine or paludal deposit occurring 10-60 feet beneath Buena Vista, Kern, and Tulare Lake beds, and parts of Fresno Slough. The clay is mainly blue or dark greenish gray, plastic, and highly organic. In some areas the unit is separated into an upper and a lower stratum by several feet of sand. A radiocarbon date of 26,780 ? 600 years was obtained from wood cored 3 feet beneath the clay. Continental deposits are arkosic beds of late Pliocene and Pleistocene (?) age and were derived from the Sierra Nevada, Tehachapi, and San Emigdio Mountains. In places, a reduced-oxidized contact transgresses the deposits derived from the Sierra Nevada. The reduced deposits consist of moderately permeable bluish-green or bluish-gray fine to medium sand, silt, and clay. The oxidized deposits consist mainly of poorly permeable yellowish-brown silt and fine sand. Deposits derived from the Tehachapi and the San Emigdio Mountains consist of poorly to moderately permeable yellowish-brown sand and silt. Continental and alluvial deposits of Tertiary and Quaternary age that were derived from the Coast Ranges consist mainly of poorly to moderately permeable yellowish-brown gravel, sand, silt, and clay. They include the Tulare Formation and overlying alluvial deposits. Alluvium is composed of coarse arkosic deposits derived from the Sierra Nevada, Tehachapi, and San Emigdio Mountains. A reduced-oxidized contact also transgresses the alluvial deposits derived from the Sierra Nevada. The oxidized deposits consist of poorly to highly permeable yellowish-brown gravel, sand, silt, and clay. The reduc

  11. Optical dating of late Quaternary deposits preserved beneath the eastern English Channel

    NASA Astrophysics Data System (ADS)

    Mellett, C. L.; Mauz, B.; Hodgson, D. M.; Plater, A. J.; Lang, A.

    2012-04-01

    A stratigraphic model detailing the sequence and nature of processes responsible for sculpting the shallow continental shelf in the eastern English Channel has been developed through the interpretation of high resolution sub-bottom seismic records. The seafloor is an erosional unconformity and large sediment bodies are limited to palaeovalley infills and offshore extensions of present day coastal environments. In simplistic terms the stratigraphic model proposes fluvial incision and deposition during sea-level lowstand with periglacial processes operating on the sub-aerially exposed shelf under cold climate conditions. Subsequent sea-level rise triggers reworking of existing deposits and infilling of the palaeovalleys with shallow marine and coastal deposits that migrate in step with sea-level rise. The frequency and magnitude of sea-level changes during the late Quaternary lends to significant reworking of sediments during each glacial/interglacial cycle and remnants of previous cycles are rarely preserved. This study uses OSL dating to test the validity of the proposed stratigraphic model. Samples for OSL dating were taken from vibrocores tied to known seismic stratigraphic units representing fluvial, coastal and colluvial depositional environments. The single-aliquot-regenerative dose protocol was applied to 1 mm aliquots of fine quartz sand and individual aliquots were rejected following the criteria proposed by Wintle and Murray (2006). All samples exhibited low sensitivity and poor recycling ratios necessitating the rejection of up to 75% of all aliquots measured. A total of 40 to 60 aliquots were accepted per sample. For all samples regardless of depositional environment, normal equivalent dose (De) distributions were observed with overdispersion values typically <25% and weighted skewness values of ~0.2 advocating the application of the Central Age Model (CAM) to estimate Des. The OSL chronology places periglacial reworking of existing estuarine deposits at ~18 ka, deposition of fluvial sediments preserved in palaeovalleys at ~15ka and progradation of a shoreface at ~8 ka. The ages are remarkably consistent with the stratigraphic model and provide the first chronological control on the timing of processes responsible for the morphological evolution of the continental shelf. We demonstrate the successful application of OSL dating to fluvial, coastal and colluvial deposits preserved in the eastern English Channel.

  12. Seismic Velocities and Thicknesses of Alluvial Deposits along Baker Creek in the Great Basin National Park, East-Central Nevada

    USGS Publications Warehouse

    Allander, Kip K.; Berger, David L.

    2009-01-01

    To better understand how proposed large-scale water withdrawals in Snake Valley may affect the water resources and hydrologic processes in the Great Basin National Park, the National Park Service needs to have a better understanding of the relations between streamflow and groundwater flow through alluvium and karst topography of the Pole Canyon Limestone. Information that is critical to understanding these relations is the thickness of alluvial deposits that overlay the Pole Canyon Limestone. In mid-April 2009, the U.S. Geological Survey and National Park Service used seismic refraction along three profiles adjacent to Baker Creek to further refine understanding of the local geology. Two refractors and three distinct velocity layers were detected along two of the profiles and a single refractor and two distinct velocity layers were detected along a third profile. In the unsaturated alluvium, average velocity was 2,000 feet per second, thickness ranged from about 7 to 20 feet along two profiles downstream of the Narrows, and thickness was at least 100 feet along a single profile upstream of the Narrows. Saturated alluvium was only present downstream of the Narrows - average velocity was 4,400 feet per second, and thickness ranged from about 40 to 110 feet. The third layer probably represented Pole Canyon Limestone or Tertiary granitic rock units with an average velocity of 12,500 feet per second. Along the upstream and middle profiles (profiles 3 and 1, respectively), the depth to top of the third layer ranged from at least 60 to 110 feet below land surface and is most likely the Pole Canyon Limestone. The third layer at the farthest downstream profile (profile 2) may be a Tertiary granitic rock unit. Baker Creek is disconnected from the groundwater system along the upstream profile (profile 3) and streamflow losses infiltrate vertically downward to the Pole Canyon Limestone. Along the downstream and middle profiles (profiles 2 and 1, respectively), the presence of a shallow water table indicates that low permeability Tertiary granitic rock may extend across the Baker Creek Drainage intersecting the Pole Canyon Limestone. The Tertiary granitic rock may be acting as a barrier to groundwater flow within the Pole Canyon Limestone.

  13. Quaternary deposits and sediment fluxes at the toe of the Barbados Accretionary Prism

    NASA Astrophysics Data System (ADS)

    Massé, L.; Faugères, J. C.; Gonthier, E.

    1995-06-01

    Sedimentologic and stratigraphic investigations on four cores collected close to the front of the Barbados accretionary prism provided information about the Quaternary depositional processes and sediment fluxes in the region. The morphology of the prism is marked by N—Soriented anticlinal ridges separated by troughs. The deposits are hemipelagic on top of the ridges and in the abyssal plain, with a mean global flux of 1.35 1.40 g cm-2 10-3 yr. The carbonate flux decreases from the prism to the abyssal plain (0.49 and 0.3 g cm-2 10-3 yr, respectively). Terrigenous material is provided by distal turbiditic plumes. It decreases slightly from the abyssal plain to the prism (1.06 and 0.9 g cm-2 10-3 yr, respectively). During cold climatic stages, it is up to 1.4 g cm-2 10-3 yr. The global flux is much higher (7.1 g cm-2 10-3 yr) in the interridge troughs, which act as sediment traps for distal turbidity currents.

  14. Correlations between radiometric analysis of Quaternary deposits and the chronology of prehistoric settlements from the southeastern Brazilian coast.

    PubMed

    Anjos, R M; Macario, K D; Lima, T A; Veiga, R; Carvalho, C; Fernandes, P J F; Vezzone, M; Bastos, J

    2010-01-01

    Natural gamma radiation measurements of sand deposits were carried out in order to study the chronology of prehistoric colonization of the Brazilian coast during the Holocene. The method employs thorium, uranium and potassium as tracers of the geological provenance of Quaternary deposits, where artificial shellmounds are found. The so-called sambaquis are archaeological settlements, characteristic of fisher-gatherers, specialized in the exploitation of shellfish. Our results show a considerable positive correlation between the formation of coastal deposits, based on cross plots of eTh/eU and eTh/K, and the antiquity of its prehistoric human occupation. PMID:19800154

  15. Quaternary investigation

    SciTech Connect

    Stieve, A.

    1991-05-15

    The primary purpose of the Quaternary investigation is to provide information on the location and age of Quaternary deposits for use in evaluating the presence or absence of neotectonic deformation or paleoliquefaction features within the Savannah River Site (SRS) region. The investigation will provide a basis for evaluating the potential for capable faults and associated deformation in the SRS vicinity. Particular attention will be paid to the Pen Branch fault.

  16. Composition and provenance of Late Pleistocene-Holocene alluvial sediments of the eastern Andean piedmont between 33 and 34° S (Mendoza Province, Argentina)

    NASA Astrophysics Data System (ADS)

    Mehl, A.; Blasi, A.; Zárate, M.

    2012-12-01

    The Andean cordillera, and its piedmont in the central western Argentina, has been long considered as one of the main source areas of detritus for the Chaco-Pampean plain sand dune fields and loess/loess-like deposits of central Argentina. The main goal of this study is to evaluate the composition of the late Pleistocene-Holocene alluvial deposits of the Andes cordillera piedmont, from 33° to 34° S. The results are interpreted in the context of the regional geology, tectonic setting of the study area and its implications in the continent-wide perspective of modern alluvial sands proposed by Potter (1994). Sampling was conducted at the alluvial stratigraphic sequences of four study sites along three Andean piedmont arroyos; modal mineralogy in the very fine sand fraction (3 phi to 4 phi) was determined using standard petrographic microscope methods. Q:F:LF average compositions indicate that the Late Pleistocene-Holocene very fine-grained alluvial sands of the Cordillera Frontal piedmont reflects the modern lithic arenites of the Argentine Association reported by Potter (1994). The results show two geologically distinct sources in the catchment areas, volcaniclastic and metamorphic rocks. High concentrations of mica and volcanic glass are likely related to particle morphologies and to the deposition sedimentary environment recorded in the alluvial sequences—floodplains. The overabundance of micas over the volcanic glass in the mid-late Holocene alluvial sequence indicates the drainage of a metamorphic area at the expense of other lithological sources. Source areas are located mainly in the Frontal cordillera, and to a lesser extent, in the piedmont Tertiary deposits, another likely source for the analyzed Quaternary alluvial sediments. The mineralogical signature of the late Pleistocene and Holocene alluvial sequences is in agreement with the composition of the southern Pampean sand mantles, loess and loess-like deposits mainly formed by a volcanic mineral assemblage with source areas placed at the headwaters of the main Andean rivers.

  17. Quaternary tephrochronology and deposition in the subsurface Sacramento-San Joaquin Delta, California, U.S.A.

    NASA Astrophysics Data System (ADS)

    Maier, Katherine L.; Gatti, Emma; Wan, Elmira; Ponti, Daniel J.; Pagenkopp, Mark; Starratt, Scott W.; Olson, Holly A.; Tinsley, John C.

    2015-03-01

    We document characteristics of tephra, including facies and geochemistry, from 27 subsurface sites in the Sacramento-San Joaquin Delta, California, to obtain stratigraphic constraints in a complex setting. Analyzed tephra deposits correlate with: 1) an unnamed tephra from the Carlotta Formation near Ferndale, California, herein informally named the ash of Wildcat Grade (<~1.450 to >~ 0.780 Ma), 2) the Rockland ash bed (~ 0.575 Ma), 3) the Loleta ash bed (~ 0.390 Ma), and 4) middle Pleistocene volcanic ash deposits at Tulelake, California, and Pringle Falls, Bend, and Summer Lake, Oregon, herein informally named the dacitic ash of Hood (<~0.211 to >~ 0.180 Ma). All four tephra are derived from Cascades volcanic sources. The Rockland ash bed erupted from the southern Cascades and occurs in up to > 7-m-thick deposits in cores from ~ 40 m subsurface in the Sacramento-San Joaquin Delta. Tephra facies and tephra age constraints suggest rapid tephra deposition within fluvial channel and overbank settings, likely related to flood events shortly following volcanic eruption. Such rapidly deposited tephra are important chronostratigraphic markers that suggest varying sediment accumulation rates in Quaternary deposits below the modern Sacramento-San Joaquin Delta. This study provides the first steps in a subsurface Quaternary stratigraphic framework necessary for future hazard assessment.

  18. Occurrence and seismic characteristics of stacked Quaternary debris-flow deposits in the Ulleung Basin, East Sea

    NASA Astrophysics Data System (ADS)

    Yoo, Dong-Geun; Lee, Young-Mi; Kang, Nyeon-Keon; Yi, Bo-Yeon; Bahk, Jang-Jun; Kim, Gil-Young

    2015-04-01

    Analysis of multi-channel seismic reflection profiles collected from the Ulleung Basin, East Sea reveals that the Quaternary sequence in this area includes eighteen stacked debris flow deposits, which are variable in the geometry and spatial distribution. Each deposit is acoustically characterized by chaotic or transparent seismic facies without distinct internal reflections and shows wedge or lens-shaped external form. Based on distribution patterns, these deposits which form a succession of vertically and/or laterally stacked wedges are widely distributed on the southern slope and cover an area of more than 8,000 km2. Their general flow direction is from south to north and the thickness gradually decreases toward the basin plain. The results of seismic interpretation suggest that sedimentation during the Quaternary was controlled mainly by tectonic effects associated with sea-level fluctuations. The back-arc closure of the East Sea that began in the Miocene caused compressional deformation along the southern margin of the Ulleung Basin, resulting in regional uplift which continued until the Pliocene. Large amounts of sediments, eroded from the uplifted blocks, were supplied to the basin through the mass transport processes, leading to the formation of stacked debris-flow deposits. Consequently, the development of debris flow deposits in the Ulleung Basin is largely controlled by regional tectonic event associated with the back-arc closure of the East Sea.

  19. Quaternary deposits and soil formation in the Aragón Pyrenees (Spain) - First results from sedimentological studies

    NASA Astrophysics Data System (ADS)

    Hirsch, Florian; Raab, Thomas; Schuhart, Stefan

    2010-05-01

    Within the scope of the research project Post LGM Pedogenesis and Geomorphodynamics in the Aragón Pyrenees funded by the DFG (Az RA 931/3-1) late Quaternary glacial, periglacial, fluvial and anthropogenic sediments are used to reconstruct the palaeoenvironment. The two research areas Gállego Valley and Aragón Valley are located in Aragón about 50 km northwest of Huesca which is a type region for Pleistocene glaciation in the Central Spanish Pyrenees. Our reconstruction of the paleoenvironment is based on a first soil mapping along catenas and the facies differentiation of the sediments. Sedimentological analyses are performed by a measurement of macrofabrics, clast roundness, lithology and followed in the laboratory by grain size and chemical analyses. Preliminary results indicate that beside the glacial also periglacial morphodynamics play a major role for the formation of the soils present in the area. Moreover, we have hints for human impacts on the soil landscape as in several profiles periglacial and glacial sediments are superimposed by colluvial sediments which we interpret as a correlative sediment of soil erosion on the slopes. The pedostratigraphy is characterized by horizontal and vertical small scale heterogeneity which also results in varying stages of pedogenesis. Sedimentological analyses show that in the unglaciated backslopes periglacial slope deposits (PSD) consisting of a Lower and an Upper Head are present. The coarse fraction (> 2 mm) of the PSDs in the unglaciated area is limited to autochthon or parautochthon material. The Upper Head clearly differs from the Lower Head and tills by higher amounts of fine material (< 2 mm) which is interpreted as a result of the eolian genesis typically mentioned for this type of PSD. Upper Heads are mainly found on sheltered sites (old forest stands) indicating the frequent erosion caused by anthropogenic land-use. On these sheltered sites luvisols are developed. Lower Heads are characterized by only a small amount of fine material and a high amount of angular clasts, whose a-axes are parallel to the slope direction. Therefore the Lower Heads are more resistant to erosion induced by anthropogenic land-use. On the exposed Lower Heads leptosols are the dominant soil type indicating a short time for soil formation. Formerly glaciated areas on the footslopes and on the valley floors are characterized by diamictic and allochthon sediments consisting solely of angular to sub-rounded clasts orientated parallel to the direction of the former glacier movement. These properties are characteristic for subglacial environments and lodgement processes. Soils on the glacigenic sediments are reddish and form cambic horizons. Anthropogenic superimposing is common on the tills with truncated profiles and colluvisols.

  20. Evaluation of ERTS-1 imagery for mapping Quaternary deposits and landforms in the Great Plains and Midwest

    NASA Technical Reports Server (NTRS)

    Morrison, R. B. (principal investigator); Hallberg, G. R.

    1973-01-01

    The author has identified the following significant results. The main landform associations and larger landforms are readily identifiable on the better images and commonly the gross associations of surficial Quaternary deposits also can be differentiated, primarily by information on landforms and soils. Maps showing the Quaternary geologic-terrain units that can be differentiated from the ERTS-1 images are being prepared for 20-odd potential study areas in Illinois, Iowa, Missouri, Kansas, Nebraska, and South Dakota. Among the more distinct features are the major moraines and outwash channels of the last (Wisconsin) glaciation. Analysis of dissection/drainage patterns from the synoptic imagery is proving useful for detecting anomalies that may be caused by stream diversions and moraines of pre-Wisconsin glaciations, by variable loess deposition, by tectonism, and other factors. Numerous abandoned river valleys have been mapped. Trend-lines of several known pre-Wisconsin moraine systems have been identified in Iowa, Nebraska, and Kansas, and also several similar trend-lines, that may indicate previously unknown moraine systems of middle and possibly early Pleistocene age, have been found in Iowa and Missouri. The area inundated by a major flood in southwestern Iowa also has been delineated from ERTS-1 imagery.

  1. Stratigraphy, sedimentology, chronology and palaeohydrology of Quaternary lacustrine deposits at Madigan Gulf, Lake Eyre, south Australia

    Microsoft Academic Search

    J. W. Magee; J. M. Bowler; G. H. Miller; D. L. G. Williams

    1995-01-01

    Madigan Gulf is a large bay at the southern end of Lake Eyre North, a major ephemerally flooded playa in arid central Australia at the southwestern margin of a vast (1,300,000 km2) internal drainage basin. The stratigraphy and chronology of the Quaternary sequence in the gulf is described from 8 cores and a cliff exposure at the gulf margin. A

  2. A New Genus and Species of Buteonine Hawk from Quaternary Deposits in Bermuda (Aves: Accipitridae)

    Microsoft Academic Search

    Storrs L. Olson

    2008-01-01

    Bermuteo avivorus, new genus and species, is described from rare Quaternary fossils from the island of Bermuda. Although clearly referable to the Buteoninae, its relationships within that group are difficult to assess. Considerable size variation may be attributable to sexual dimorphism associated with bird-catching behavior. It is uncertain if the species survived into the historic period. Factors contributing to the

  3. Evaluation of ERTS-1 imagery for mapping Quaternary deposits and landforms in the Great Plains and Midwest

    NASA Technical Reports Server (NTRS)

    Morrison, R. B. (principal investigator); Hallberg, G. R.

    1973-01-01

    The author has identified the following significant results. The main landform associations and larger landforms are readily identifiable on the better images and commonly the gross associations of surficial Quaternary deposits also can be differentiated, primarily by information on landforms and soils. Maps showing the Quaternary geologic-terrain units that can be differentiated from the ERTS-1 images are being prepared for study areas in Illinois, Iowa, Missouri, Kansas, Nebraska, and South Dakota. Preliminary maps at 1:1 million scale are given of two of the study areas, the Peoria and Decatur, Illinois, 1 deg x 2 quadrangles. These maps exemplify the first phase of investigations, which consists of identifying and mapping landform and land use characteristics and geologic-surficial materials directly from ERTS-1 images alone, without input of additional data. These maps shown that commonly the boundaries of geologic-terrain units can be identified more accurately on ERTS-1 images than on topographic maps of 1:250,000 scale. From analysis of drainage patterns, stream-divide relations, and tone and textural variations on the ERTS-1 images, the trends of numerous moraines of Wisconsinan and possibly some of Illinoian age were mapped. In the Peoria study area the trend of a buried valley of the Mississippi River is revealed.

  4. Evaluation of ERTS-1 imagery for mapping Quaternary deposits and landforms in the Great Plains and Midwest

    NASA Technical Reports Server (NTRS)

    Morrison, R. B. (principal investigator); Hallberg, G. R.

    1973-01-01

    The author has identified the following significant results. The main landform associations and larger landforms are readily identifiable on the better images and commonly the gross associations of surficial Quaternary deposits also can be determined primarily by information on landforms and soils (obtained by analysis of stream dissection and drainage and stream-divide patterns, land use patterns, etc.). Maps showing the Quaternary geologic-terrain units that can be distinguished on the ERTS-1 images are being prepared for study areas in Illinois, Iowa, Missouri, Kansas, Nebraska, and South Dakota. Preliminary maps of 1:1,000,000 scale are included for three of the study areas: the Grand Island and Fremont, Nebraska, and the Davenport, Iowa-Illinois, 1 deg x 2 deg quadrangles. These maps exemplify the first phase of investigations, which consists of identifying and mapping landform and land use characteristics and geologic-surficial materials directly from the ERTS-1 images alone, with no additional information. These maps show that commonly the boundaries of geologic-terrain units can be delineated more accurately on ERTS-1 images than on topographic maps at 1:250,000 scale.

  5. A monoclinic, pseudo-orthorhombic Au-Hg mineral of potential economic significance in Pleistocene Snake River alluvial deposits of southeastern Idaho

    USGS Publications Warehouse

    Desborough, G.A.; Foord, E.E.

    1992-01-01

    A mineral with the approximate composition of Au94Hg6 - Au88Hg12 (atomic %) has been identified in Pleistocene Snake River alluvial deposits. The gold-mercury mineral occurs as very small grains or as polycrystalline masses composed of subhedral to nearly euhedral attached crystals. Vibratory cold-polishing techniques with 0.05-??m alumina abrasive for polished sections revealed a porous internal texture for most subhedral crystals after 48-72 hours of treatment. Thus, optical character (isotropic or anisotropic) could not be determined by reflected-light microscopy, and pore-free areas were too small for measurement of reflectance. X-ray-diffraction lines rather than individual reflections (spots), on powder camera X-ray films of unrotated spindles of single grains that morphologically appear to be single crystals, indicate that individual subhedral or euhedral crystals are composed of domains in random orientation. Thus, no material was found suitable for single-crystal X-ray diffraction studies. -from Authors

  6. Frozen Quaternary Deposits of the Laptev Sea Region as a Reservoir of Organic Carbon: Total Content and Composition.

    NASA Astrophysics Data System (ADS)

    Kholodov, A.; Schirrmeister, L.; Shirshova, L.; Zolotareva, B.; Meyer, H.; Knoblauch, C.; Fahl, K.

    2007-12-01

    Permafrost is a significant reservoir and potential source of ancient organic matter (OM) such as plant remains, humified organics, etc. and greenhouse gases. In according with different estimations 1 cubic meter of frozen deposits in this region consists up to 10 kg of Corg. Due to the degradation of permafrost under the both modern geological processes and global warming, this organic carbon is easily released into the present biogeochemical cycle Humus parameters, elementary and isotopic composition of OM, dissolved organic carbon content and some biomarkers in the following types of quaternary deposits were determined: Middle Pleistocene deposits contain 1-2% of TOC and characterised by the ratios of C/N 5-7,5 (syncryogenic) and 10-12 (epycryogenic). Late Pleistocene syncryogenic deposits composed by true syncryogenic deposits and buried soils. The former characterized by the 1-2% of TOC and C/N ratio 9-11 the later 4-16% of TOC and 12-16 C/N ratio. Late Pleistocene-Holocene taberal deposits. TOC - 1%, C/N - 10-12 Holocene alas deposits. TOC 4-6%, C/N - 10-12. Main part of total carbon is organic origin. Carbonates consist only 31 - 20 %. The following conclusions can be done: More transformed OM is in the buried soils and alas deposits. OM of syncryogenic deposits is a most labile. TOC and stage of organic matter transformation in the syncryogenic deposits depends on ratio of sedimentation and freezing rate. Decreasing of freezing rate leads to the more deposition and to deeper transformation of OM. Most transformed OM is in alas deposits and buried soils. About 20% of TOC presented by humus. Syncryogenic and taberal deposits are not so matured (humus content 15%). Content of organic matter potentially available to be dissolved in the water is low in the all investigated deposits. It consists approximately the 1-1,5% of TOC in Ice Complex deposits and 2-3% in alas and taberal deposits. Determination of biomarkers composition (n-alkanes, fatty acids and sterols) in alas and taberal deposits was carried out. Main part of organic matter in investigated deposits is presented by n-alkanes (37-74%, generally 55-60%). Fatty acids and sterols consist 13-22 and 2-7% correspondingly. On the base of the analyses conclusions about the main source of organic matter in the all investigated deposits can be done. Predomination of odd carbon-numbered long-chain n-alkanes (with 25-35 carbon atoms) and saturated fatty acids with long carbon chain (> C22) are character for terrestrial higher plants. There is a positive correlation of TOC and long-chain alkanes. All investigated deposits characterized by the low values of isotope C13 (from -24 to -24) what reflects the low decomposition of organic matter. Research was supported by RFBR (05-05-64062).

  7. Redoximorphic paleosols in alluvial and lacustrine deposits, 1.8 GA Lochness Formation, Mount Isa, Australia: Pedogenic processes and implications for paleoclimate

    SciTech Connect

    Driese, S.G. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Geological Sciences; Simpson, E.L. [Kutztown Univ., PA (United States). Dept. of Physical Sciences; Eriksson, K.A. [Virginia Polytechnic Institute and State Univ., Blacksburg, VA (United States). Dept. of Geological Sciences

    1995-10-02

    Paleosols in the Lochness Formation (1.8 Ga, Australia) include both rare, non-red and abundant, strongly reddened varieties that formed at subaerial exposure surfaces in both ephemeral-river and lacustrine settings. Physical processes dominated non-red paleosols, which were characterized by repeated episodes of desiccation, shrinking, and cracking alternating with wetting and introduction of sand, silt, clay, and iron oxyhydroxides into planar voids. Redoximorphic (oxidation-reduction) processes were especially intense for the red paleosols; redox depletions of Fe and Mn (hypoalbans) occur immediately adjacent to desiccation-related macropores and peds, whereas redox concentrations of Fe and Mn (quasi-coatings) occur within paleosol matrix adjacent to redox depletions. Redoximorphic features indicate periodic water infiltration and saturation, accompanied by development of reducing conditions along planar macropores and ped surfaces in Lochness Formation paleosols. Variations in soil saturation were caused by seasonal fluctuations of lake level in lacustrine deposits, and by formation of perched saturation zones within floodplain deposits, respectively. Occurrences of red, hematitic paleosols in the Lochness Formation are compatible with previous interpretations of a weakly oxygenated 1.8 Ga paleoatmosphere. Redoximorphic features in the paleosols suggest a warm to cool temperate paleoclimate characterized by seasonal saturation, by analogy with Quaternary redoximorphic soils. A minimal concentration of organic C, possibly of microbial or bacterial origin, must have been present in these Proterozoic soils to allow for Fe reduction.

  8. Geomorphology of Late Quaternary Mass Movement Deposits using a Decimetre-Resolution 3D Seismic Volume: Case Studies from Windermere, UK, and Trondheimsfjorden, Norway

    Microsoft Academic Search

    M. E. Vardy; J. K. Dix; T. Henstock; J. M. Bull; L. Pinson; J. L'Heureux; O. Longva; L. Hansen; S. Chand; M. Gutowski

    2009-01-01

    We present results from decimetre resolution 3D seismic volumes acquired over Late Quaternary mass movement deposits in both Lake Windermere, UK, and the Trondheim Harbour area, central Norway. Both deposits were imaged using the 3D Chirp sub-bottom profiler, which combines the known, highly repeatable source waveform of Chirp profilers with the coherent processing and interpretation afforded by true 3D seismic

  9. Using the Messinian and Plio-Quaternary deposits as markers of the vertical motions in the tectonically inverted Algerian margin

    NASA Astrophysics Data System (ADS)

    Strzerzynski, P.; Lofi, J.; Sage-Khadir, F.; Gaullier, V.; Cattaneo, A.; Déverchère, J.

    2009-12-01

    The Algerian margin represents one of the rare examples of tectonically inverted margins worldwide. The inversion is characterized by blind reverse thrust faults dipping landwards the below the continental slope, and by uplift of the coastal domain. The inversion process is active as evidenced by the offshore seismicity of Algeria (2003 Boumerdes earthquake, Mw 6.9); however the onset of inversion is poorly constrained. The morphology of the Algerian margin results from the interplay between tectonic and sedimentation together with periodic sea level changes during Quaternary. A major sea level fall at the end of Miocene marks the onset of the Messinian Salinity Crisis (MSC). In this study, we focus on a part of the Algerian margin located west of Algiers: the Khair al Din Bank (KADB). The KADB is a major structure interpreted as a tilted block originated during the opening of the Algerian basin in early Miocene. Because of its weak (low) slope, the sedimentary record all along the continental slope is better preserved than in the rest of the Algerian margin. The aim of this study is to constrain deformation and vertical motion of several sedimentary units in order to quantify the amount of uplift and the timing of inversion. We selected for uplift calculations 6 sedimentary units as follows. Sedimentary units onshore are: the highest marine terrace, the marine-continental transition and the MIS 5.5 uplifted beach. Sedimentary units offshore are: the boundary of the upper Unit of the MSC, and the erosion surfaces of the MIS 6 and MIS 2 sea level lowstand. The age of these units ranges between 5.6 Ma and 20 ka BP and permits to estimate the uplift and uplift rates all along the Plio-Quaternary time. Our interpretation is based on geophysical data acquired in 2003 (Maradja 1 cruise). We describe the main characteristics of the MSC erosion surface, i.e. the initial stage, and the sedimentary evolution during the Plio-Quaternary time. During the MSC sea level lowstand, the KADB area formed a deeply incised subaerial area continued in the marine domain by detrital chaotic deposits and evaporitic series. The subaerial domain exhibits a peculiar shape related to the inherited morphology of the passive margin as the river valley flows to the ENE and turns abruptly to the WNW on the mid-slope. In the inner shelf, the sedimentary evolution during Plio-Quaternary time is mostly characterized by the deposition of foresets and the absence of sediment aggradation, suggesting that the sedimentary evolution is dominated by a long term tectonic uplift of the KADB. Plio-Quaternary anticlines are present both onshore and offshore. As these structures do not correspond with crests and valleys of the MCS drainage network, we suggest that folding occurred after the MSC. We estimate maximum uplift values of 400 m for the oldest sedimentary marker suggesting that the inversion of the margin started at least 3.5 Ma ago.

  10. Erosion and deposition on the Pajarito Plateau, New Mexico, and implications for geomorphic responses to late Quaternary climatic changes

    SciTech Connect

    Reneau, S.L.; McDonald, E.V.; Gardner, J.N.; Longmire, P.A. [Los Alamos National Lab., NM (United States); Kolbe, T.R. [Woodward-Clyde Federal Services, Oakland, CA (United States); Carney, J.S. [Kent State Univ., OH (United States). Dept. of Geology; Watt, P.M. [New Mexico Univ., Albuquerque, NM (United States). Dept. of Earth and Planetary Sciences

    1996-04-01

    The Pajarito Plateau of northern New Mexico contains a rich and diverse record of late Quaternary landscape changes in a variety of geomorphic settings that include gently-sloping mesa tops, steep canyon walls, and canyon bottoms. A broad range of investigations during the past decade, motivated by environmental and seismic hazard concerns, have resulted in examination of the characteristics, stratigraphy, and age of sediments and soils at numerous locations throughout the Plateau. Geochronologic control is provided by >140 radiocarbon dates supplemented by soil characterization and tephrochronology. In this paper we first summarize some of the results of recent and ongoing work on late Quaternary deposits on the Pajarito Plateau, illustrating both the complexity of the geomorphic record and some common elements that have been observed in multiple locations. We then use these observations, in combination with other work in the Southwest, to make some inferences about the local geomorphic response to regional climatic changes. Because the geomorphic and paleoclimatic records are fragmentary, and because the relations between large scale climate changes and local variations in precipitation, vegetation, and geomorphic processes are not fully understood, many uncertainties exist concerning the response of the local landscape to past climatic fluctuations. In addition, variations in local landscape sensitivity related to prior erosional history and spatial variations in vegetation, and the localized nature of many storms, probably contribute to the complexity of the geomorphic record. Nevertheless, the work discussed in this paper suggests a strong relation between regional climatic changes and local geomorphic history, and provides a framework for considering relations between modem processes, the record of past landscape changes, and future erosion and deposition on the Plateau and in surrounding areas.

  11. Late Quaternary history of the Vakinankaratra volcanic field (central Madagascar): insights from luminescence dating of phreatomagmatic eruption deposits

    NASA Astrophysics Data System (ADS)

    Rufer, Daniel; Preusser, Frank; Schreurs, Guido; Gnos, Edwin; Berger, Alfons

    2014-05-01

    The Quaternary Vakinankaratra volcanic field in the central Madagascar highlands consists of scoria cones, lava flows, tuff rings, and maars. These volcanic landforms are the result of processes triggered by intracontinental rifting and overlie Precambrian basement or Neogene volcanic rocks. Infrared-stimulated luminescence (IRSL) dating was applied to 13 samples taken from phreatomagmatic eruption deposits in the Antsirabe-Betafo region with the aim of constraining the chronology of the volcanic activity. Establishing such a chronology is important for evaluating volcanic hazards in this densely populated area. Stratigraphic correlations of eruption deposits and IRSL ages suggest at least five phreatomagmatic eruption events in Late Pleistocene times. In the Lake Andraikiba region, two such eruption layers can be clearly distinguished. The older one yields ages between 109 ± 15 and 90 ± 11 ka and is possibly related to an eruption at the Amboniloha volcanic complex to the north. The younger one gives ages between 58 ± 4 and 47 ± 7 ka and is clearly related to the phreatomagmatic eruption that formed Lake Andraikiba. IRSL ages of a similar eruption deposit directly overlying basement laterite in the vicinity of the Fizinana and Ampasamihaiky volcanic complexes yield coherent ages of 68 ± 7 and 65 ± 8 ka. These ages provide the upper age limit for the subsequently developed Iavoko, Antsifotra, and Fizinana scoria cones and their associated lava flows. Two phreatomagmatic deposits, identified near Lake Tritrivakely, yield the youngest IRSL ages in the region, with respective ages of 32 ± 3 and 19 ± 2 ka. The reported K-feldspar IRSL ages are the first recorded numerical ages of phreatomagmatic eruption deposits in Madagascar, and our results confirm the huge potential of this dating approach for reconstructing the volcanic activity of Late Pleistocene to Holocene volcanic provinces.

  12. Uranium-trend dating of quaternary deposits in the Nevada Test Site area, Nevada and California

    Microsoft Academic Search

    J. N. Rosholt; C. A. Bush; W. J. Carr; D. L. Hoover; W. C. Swadley; J. R. Jr. Dooley

    1985-01-01

    The uranium-trend dating method has been used to estimate the ages of alluvium, colluvium, altered volcanic ash, and eolian deposits in the Nevada Test Site area. For dating of deposits of 5000 to 800,000 years age, the open-system technique consists of determining a linear trend from analyses of four to ten channel samples collected at different depths in a depositional

  13. Processes of late Quaternary turbidity current flow and deposition on the Var deep sea fan, northwest Mediterranean sea

    SciTech Connect

    Piper, D. (Atlantic Geoscience Centre, Dartmouth, Nova Scotia (Canada)); Savoye, B. (IFREMER, Plouzane (France))

    1993-09-01

    Late Quaternary sedimentation patterns on the Var deep-sea fan are known from high-resolution seismic boomer profiles (vertical resolution < 1 m), piston cores, SAR side-scan sonargraphs, and submersible dives. Foram biostratigraphy and radiocarbon dating provide chronologic control that is seismically correlated across the fan. Regional erosional events correspond to the isotopic state 2 and 6 glacial maxima. A widespread surface sand layer was deposited from the 1979 turbidity current, which broke two submarine cables. Numerical modeling constrains its character. A small slide on the upper prodelta developed into an accelerating turbidity current, which eroded sand from the Var canyon. The current was 30 m thick in the upper valley, expanding downflow to >120 m, where it spilled over the eastern Var sedimentary ridge at a velocity of 2.5 ms[sup [minus]1]. Other Holocene turbidity currents (with a 103-yr recurrence interval) were muddier and thicker, but also deposited sand on middle fan-valley levees and are inferred to have had a similar slide-related origin. Late Pleistocene turbidity currents deposited on the high Var sedimentary ridge. The presence of sediment waves and the cross-flow slope inferred from levee asymmetry indicate that some flow were hundreds of meters thick, with velocities of 0.35 ms[sup [minus]1]. Estimated times for deposition of thick levee mud beds are many days or weeks. Late Pleistocene flows therefore are interpreted to result from hyperpycnal flow of glacial outwash in the Var River. Variation in late Pleistocene-Holocene turbidite sedimentation thus is controlled more by changes in sediment supply than by sea level.

  14. ELEVATED FOSSIL CORAL DEPOSITS IN THE HAWAIIAN ISLANDS: A MEASURE OF ISLAND UPLIFT IN THE QUATERNARY

    E-print Network

    Luther, Douglas S.

    ELEVATED FOSSIL CORAL DEPOSITS IN THE HAWAIIAN ISLANDS: A MEASURE OF ISLAND UPLIFT Gary McMurtry Johanna Resig #12;ABSTRACT The origin of emerged marine fossils in the Hawaiian Islands waves swept up to 326 m on Lanai and neighboring islands depositing marine fossils 105 ka; (3

  15. A comparative study of Quaternary dating techniques applied to sedimentary deposits in southwest Victoria, Australia

    NASA Astrophysics Data System (ADS)

    Sherwood, J.; Barbetti, M.; Ditchburn, R.; Kimber, R. W. L.; McCabe, W.; Murray-Wallace, C. V.; Prescott, J. R.; Whitehead, N.

    At five sites in western Victoria a total of five Quaternary dating techniques have been applied to shell beds varying in age from Holocene to beyond the last interglacial. To examine the age concordancy of the methods, 89 analyses were conducted—16 by radiocarbon, 26 by uranium series disequilibrium, 26 by amino acid racemisation, 5 by thermoluminescence and 16 by electron spin resonance, the latter previously reported by Goede (1989). Uncertainties associated with diagenetic environments of samples precluded reliable numerical age assignments for beds older than Holocene. Instead, relative dating of shell beds was based on a reference site (Goose Lagoon) which was assigned to the last interglacial based on its morphostratigraphic setting and concordant results of three of the dating methods (amino acid racemisation, uranium series disequilibrium and electron spin resonance). Overall there was considerable agreement between methods although not all were applied to each site. Uranium series dating proved most problematical. Migration of radionuclides between groundwater and shells introduced large errors at one site and led to appreciable uncertainties at others.

  16. Field evidence of seismites in Quaternary deposits of the Jijel (Eastern Algeria) coastal region

    NASA Astrophysics Data System (ADS)

    Benhamouche, A.; Nedjari, A.; Bouhadad, Y.; Machane, D.; Oubaiche, E.; Sidi Said, N.

    2014-04-01

    Jijel has been hit by a strong earthquake in 1856 that triggered a destructive tsunami. Field geological investigations show that the marine terrace deposits (Tyrrhenian or likely Eutyrrhenian) exhibit several types of soft sediment deformation features including sismoslumps, thixotropic bowls, thixotropic wedges, and diapir-like structures. In addition, paleo-liquefaction features represented by neptunian and injection dikes have been observed in the sand dune deposits (Aterian or Würm). Furthermore, typical paleo-earthquake-induced ground failures including lateral spreading, paleo-landslides, and sand volcanoes have been observed in recent, likely, Holocene deposits. Such features, remarkably comparable to present-day earthquake-induced ground failures showing clearly repetitive occurrence of past events may constitute a precious material for future paleo-seismic investigation. The various features have been interpreted herein as seismites associated to strong earthquakes produced likely by the potentially active faults previously identified in the area.

  17. Three-dimensional sedimentary architecture of Quaternary deposits; a case study of environmental sedimentology (Bam, Iran)

    Microsoft Academic Search

    K. Rezaei; B. Guest; A. Friedrich; F. Fayazi; M. Nakhaei; H. Bakhtiari; L. Nouri

    2009-01-01

    Detailed 3-D analysis of the sedimentary structure and stratigraphy of these deposits allows for an accurate understand of sedimentary model of basin. This paper presents a case study in Bam (SE Iran) reconstructing the 3-D distribution of fluvial sediments based on a high resolution, process-orientated sedimentary facies classification and lithostratigraphy. We investigated the mean grain size with vertical and horizontal

  18. Geophysical Characterization of the Quaternary-Cretaceous Contact Using Surface Resistivity Methods in Franklin and Webster Counties, South-Central Nebraska

    USGS Publications Warehouse

    Teeple, Andrew P.; Kress, Wade H.; Cannia, James C.; Ball, Lyndsay B.

    2009-01-01

    To help manage and understand the Platte River system in Nebraska, the Platte River Cooperative Hydrology Study (COHYST), a group of state and local governmental agencies, developed a regional ground-water model. The southern boundary of this model lies along the Republican River, where an area with insufficient geologic data immediately north of the Republican River led to problems in the conceptualization of the simulated flow system and to potential problems with calibration of the simulation. Geologic descriptions from a group of test holes drilled in south-central Nebraska during 2001 and 2002 indicated a possible hydrologic disconnection between the Quaternary-age alluvial deposits in the uplands and those in the Republican River lowland. This disconnection was observed near a topographic high in the Cretaceous-age Niobrara Formation, which is the local bedrock. In 2003, the U.S. Geological Survey, in cooperation with the COHYST, collected surface geophysical data near these test holes to better define this discontinuity. Two-dimensional imaging methods for direct-current resistivity and capacitively coupled resistivity were used to define the subsurface distribution of resistivity along several county roads near Riverton and Inavale, Nebraska. The relation between the subsurface distribution of resistivity and geology was defined by comparing existing geologic descriptions of test holes to surface-geophysical resistivity data along two profiles and using the information gained from these comparisons to interpret the remaining four profiles. In all of the resistivity profile sections, there was generally a three-layer subsurface interpretation, with a resistor located between two conductors. Further comparison of geologic data with the geophysical data and with surficial features was used to identify a topographic high in the Niobrara Formation near the Franklin Canal which was coincident with a resistivity high. Electrical properties of the Niobrara Formation made accurate interpretation of the resistivity profile sections difficult and less confident because of similar resistivity of this formation and that of the coarser-grained sediment of the Quaternary-age deposits. However, distinct conductive features were identified within the resistivity profile sections that aided in delineating the contact between the resistive Quaternary-age deposits and the resistive Niobrara Formation. Using this information, an interpretive boundary was drawn on the resistivity profile sections to represent the contact between the Quaternary-age alluvial deposits and the Cretaceous-age Niobrara Formation. A digital elevation model (DEM) of the top of the Niobrara Formation was constructed using the altitudes from the interpreted contact lines. This DEM showed that the general trend of top of the Niobrara Formation dips to the southeast. At the north edge of the study site, the Niobrara Formation topographic high trends east-west with an altitude range of 559 meters in the west to 543 meters in the east. Based on the land-surface elevation and the Niobrara Formation DEM, the estimated thickness of the Quaternary-age alluvial deposits throughout the study area was mapped and showed a thinning of the Quaternary-age alluvial deposits to the north, approximately where the topographic high of the Niobrara Formation is located. This topographic high in the Niobrara Formation has the potential to act as a barrier to ground-water flow from the uplands alluvial aquifer to the Republican River alluvial aquifer as shown in the resistivity profile sections. The Quaternary-age alluvial deposits in the uplands and those in the Republican River Valley are not fully represented as disconnected because it is possible that there are ground-water flow paths that were not mapped during this study.

  19. Amino-acid racemizarion in Quaternary shell deposits at Willapa Bay, Washington

    USGS Publications Warehouse

    Kvenvolden, K.A.; Blunt, D.J.; Clifton, H.E.

    1979-01-01

    Extents of racemization ( d l ratios) of amino acids in fossil Saxidomus giganteus (Deshayes) and Ostrea lurida Carpenter were measured on shell deposits exposed at 21 sites on the east side of Willapa Bay, Washington. Amino acids from Saxidomus show less variability in d Spl ratios and, therefore, are of greater use in correlation and age estimation than are amino acids from Ostrea. Shells of two different ages, about 120,000 ?? 40,000 yr old and about 190,000 ?? 40,000 yr old, are present. These ages correspond to Stages 5 and 7 of the marine isotope record defined by Shackleton and Opdyke in 1973 and hence the shell deposits likely formed during two different high stands of sea level. The stratigraphic record at Willapa Bay is consistent with this interpretation. ?? 1979.

  20. Ochotona(Lagomorpha) from Late Quaternary Cave Deposits in Eastern North America

    Microsoft Academic Search

    Frederick Grady

    1996-01-01

    Pikas (Ochtona)—small gnawing mammals, related to rabbits—range today throughout parts of the Northern Hemisphere, but had a wider distribution during the Pleistocene. Nine caves from northeastern North America (a region not occupied by pikas today) have Pleistocene deposits containing remains ofOchotona.We examine 526 fossil specimens (ranging in age from approximately 850,000 to 8670 yr B.P.) from five of these caves.

  1. Regional geologic framework of Neogene-Quaternary deposits, Louisiana continental shelf

    SciTech Connect

    Shideler, G.L.

    1985-01-01

    The Louisiana Continental Shelf of the northern Gulf Coast Basin is one of the most prolific hydrocarbon provinces in the Nation. Its structural and stratigraphic characteristics were studied by means of a regional network of dip and strike cross sections based on subsurface data from wells penetrating to depths as great as 19,000 ft (5791 m) below mean sea level. The cross sections illustrate a gulfward-thickening wedge of terrigenous clastic Cenozoic deposits that have a complex structural fabric; structures are largely attributed to extensive depositional loading, which result in gravity failure and widespread diapirism. Major structural elements include systems of coast-parallel, syndepositional faults characterized by down-to-basin displacement, sectional thickening on the downthrown side, and increasing stratigraphic throw with depth. Abundant piercement salt domes, as well as numerous post-depositional fold sand gravity fault systems, are also present. The cross-sectional network illustrates the spatial distribution of about 30 chronostratigraphic units ranging in age from early Miocene to late Pleistocene. Regional variations in stratigraphic thickness reflect both coast-parallel and gulfward migrations of the basinal depocenter. Induction-electrical logs indicate the presence of three magnafacies that are defined on the basis of sand-shale proportions. Downdip facies changes to progressively more argillaceous units indicate a gulfward transition from continental to deep-water marine paleoenvironments.

  2. Industrial deposition of binary, ternary, and quaternary nitrides of titanium, zirconium, and aluminum

    SciTech Connect

    Knotek, O.; Muenz, W.D.; Leyendecker, T.

    1987-07-01

    Improved wear behavior compared to chemically vapor deposited (CVD) and physically vapor deposited (PVD) TiN coatings have been found with (Ti,Al)N, (Ti,Zr)N, and (Ti,Al,V)N coatings using high-speed steel and cemented carbide substrates. High-speed drills coated by (Ti,Al)N films, produced from Ti:Al 50:50 at. % targets revealed in certain cases up to three times better performance than conventionally TiN ion plated tools. In the case of cemented carbides the flank and crater wear could be improved considerably also up to three times compared to CVD TiN/TiC depending on cutting conditions. Basic correlations between process and film characteristics of new multicomponent hard coating have been established. Planar magnetron sources and powder metallurgically prepared targets in an industrially useful ion plating deposition process have been developed and proved under production conditions. The first part of the paper describes the basic research and development of new coating materials. The second part involves the industrial application in batch type and in-line PVD coaters using the sputter ion plating process with magnetron sources in double-cathode arrangements. Finally, wear tests of coated cutting tools, conducted through by different institutions, show the outstanding wear behavior of the new multicomponent coatings.

  3. Late Pliocene to Late Quaternary Apparent Exposure Ages from Glacial Deposits in Ak-Shyrak, Central Kyrgyz Tian Shan

    NASA Astrophysics Data System (ADS)

    Blomdin, R.; Harbor, J.; Stroeven, A. P.; Petrakov, D. A.; Gribenski, N.; Heyman, J.; Ivanov, M.; Caffee, M. W.; Hättestrand, C.; Lifton, N. A.; Rogozhina, I.; Usubaliev, R.

    2014-12-01

    The Tian Shan in central Asia is one of the world's highest mountain ranges. The 2500 km-long WSW-ENE-trending arc of mountains extends from the western Kyrgyz Republic across northwestern China and almost to the border with Mongolia. Understanding the glacial history of this vast region is important because there is a general lack of paleoclimatic data from this highly continental location, at the confluence of major climate systems, and because glaciers are sensitive monitors of climate change. We examine the glacial history of the Ak-Shyrak massif and surrounding plateaus with average altitudes of ~3500 m a.s.l. To reconstruct the glacial history of this area we use a combined approach including geomorphological mapping, and cosmogenic nuclide surface exposure dating of erratic boulders on glacial landforms. We observe large site-specific scatter in our 10Be and 26Al exposure ages. Apparent minimum surface exposure ages range from ~2 ka to ~2.5 Ma, with early Quaternary- late Pliocene apparent exposure ages relating to some of the highest 10Be concentrations ever recorded for glacial deposits. Most dated boulders, however, fall in the apparent exposure age range of 100 ka to 300 ka. Consistent with previous results from the western and central Tian Shan, none of our boulders record a global last glacial maxima expansion of glaciers, and this contrasts to data from the eastern Kyrgyz Tian Shan. This spatial variation in glacier extent might be due to differences in paleoclimate. However, local physiographic conditions (e.g. altitude, slope, aspect) or external forcing factors other than climate (e.g., landslides) may cause local or regional differences in glacier response. We refrain from assigning mapped glacial advances to marine oxygen isotope stages because of the considerable age scatter. Finally we assess and discuss possible reasons for the observed age scatter and early Quaternary-late Pliocene apparent exposure ages in terms of prior and/or incomplete exposure histories of individual samples and compare our data to other regional datasets.

  4. Lithology, mineralogy, and paleontology of Quaternary lake deposits in Long Valley Caldera, California

    USGS Publications Warehouse

    Fournier, R.B.

    1989-01-01

    Drill cores and cuttings from two drill holes, about 3 km apart, in Long Valley caldera, Mono County, California, were studied using x-ray diffraction and optical methods. A thick sequence of tuffs and lake sediments was encountered in LVCH-1 (1,000 ft deep) and Republic well 66-29 (6,920 ft deep), drilled in the southeast part of the Long Valley caldera. Ostracods, diatoms, and isotopic data indicate that the sediments and tuffs were deposited in a shallow caldera lake which changed in salinity over time. Conditions ranged from very saline in the older lake to fresh in the youngest. The sequence of secondary minerals from top to bottom is: clinoptilolite, mordenite, analcime, K-feldspar (and albite). In some geothermal systems, this sequence of secondary minerals is a function of temperature; however, the paleontological and isotopic data indicate that the change in secondary minerals with increasing depth is due to the older strata being deposited in a more saline environment. No mineralogical evidence of hydrothermal alteration is present, although the high lithium content of some clays and feldspars and the isotopic composition of some sulfate (gypsum) seems to require a hydrothermal source. (Lantz-PTT)

  5. Potential impacts of damming the Juba Valley, western Somalia: Insights from geomorphology and alluvial history

    NASA Astrophysics Data System (ADS)

    Williams, Martin

    2014-05-01

    In 1988 plans were well advanced to dam the Juba River in western Somalia. The aims of the Baardheere Dam Project were to generate hydroelectric power for the capital Mogadishu, and to provide water for irrigation in the Juba Valley. A reconnaissance survey on foot along 500 km of the river upstream of the proposed dam site at Baardheere and detailed geomorphic mapping from air photos provided a basis for reconstructing the late Quaternary alluvial history of the river and for assessing the potential impact of the proposed dam. The Juba River rises in the Ethiopian Highlands and is the only river in Somalia that flows to the sea. Its history reflects climatic events in Ethiopia, where the Rift Valley lakes were very low during the LGM (21±2 ka), and high for about 5, 000 years before and after then. Cave deposits in Somalia indicate wetter conditions at 13, 10, 7.5 and 1.5 ka. Alluvial terraces in the Juba Valley range in age from late Pleistocene to late Holocene but only attain a few metres above the present floodplain. This is because the dry tributary valleys contain limestone caves and fissures that divert any high flows from the parent river underground, a process not known when the project was first approved. The oldest preserved terrace was cemented by calcrete by 40 ka. Alluvial gravels were deposited at the outlet of dry tributary valleys during times of episodic high-energy flow between 26 ka and 28 ka. Finely laminated shelly sands accumulated at 10 ka to form the 5 m terrace. The 2 m terrace was laid down 3.2 ka ago as a slackwater deposit. The lack of high-level alluvial terraces raises doubts over plans to dam the river, since rapid leakage would occur from side valleys and the reservoir would not attain the height needed to generate hydroelectric power. It would submerge all existing arable land along the river. Finally, the presence in the late Holocene alluvium of the sub-fossil gastropods Bulinus truncatus and Biomphalaria pfeifferi, which are the two main vectors of schistosomiasis in northeast Africa, suggests that this parasitic disease could become endemic across the valley. Any future plans to manage the Juba River need to take proper account of alluvial history and geomorphic processes.

  6. Isopachs of Quaternary deposits, Fremont 1- by 2- degree Quadrangle and part of Omaha Quadrangle, Nebraska, digitized from a published 1:250,000-scale geologic map

    USGS Publications Warehouse

    Zelt, R.B.; Patton, E.J.

    1995-01-01

    A geologic map showing the isopachs of Quaternary deposits in the Fremont and part of the Omaha, Nebraska, 1- by 2-degree quadrangles was published at a scale of 1:250,000 in 1975 (Burchett and others, 1975). This report describes the conversion of Quaternary thickness data into a digital geographic data set. A film separation of the published isopachs was scan-digitized and processed to produce digital geographic data. Geographic feature attributes and data-set documentation also are included in the digital data set. The digital data set are formatted for distribution with accordance with the Spatial Data Transfer Standard approved by the U.S. National Institute of Standards and Technology.

  7. Late Tertiary and Quaternary geology of the Tecopa basin, southeastern California

    SciTech Connect

    Hillhouse, J.W.

    1987-12-31

    Stratigraphic units in the Tecopa basin, located in southeastern California, provide a framework for interpreting Quaternary climatic change and tectonism along the present Amargosa River. During the late Pliocene and early Pleistocene, a climate that was appreciably wetter than today`s sustained a moderately deep lake in the Tecopa basin. Deposits associated with Lake Tecopa consists of lacustrine mudstone, conglomerate, volcanic ash, and shoreline accumulations of tufa. Age control within the lake deposits is provided by air-fall tephra that are correlated with two ash falls from the Yellowstone caldera and one from the Long Valley caldera. Lake Tecopa occupied a closed basin during the latter part, if not all, of its 2.5-million-year history. Sometime after 0.5 m.y. ago, the lake developed an outlet across Tertiary fanglomerates of the China Ranch Beds leading to the development of a deep canyon at the south end of the basin and establishing a hydrologic link between the northern Amargosa basins and Death Valley. After a period of rapid erosion, the remaining lake beds were covered by alluvial fans that coalesced to form a pediment in the central part of the basin. Holocene deposits consist of unconsolidated sand and gravel in the Amargosa River bed and its deeply incised tributaries, a small playa near Tecopa, alluvial fans without pavements, and small sand dunes. The pavement-capped fan remnants and the Holocene deposits are not faulted or tilted significantly, although basins to the west, such as Death Valley, were tectonically active during the Quaternary. Subsidence of the western basins strongly influenced late Quaternary rates of deposition and erosion in the Tecopa basin.

  8. Ground-water quality in Quaternary deposits of the central High Plains aquifer, south-central Kansas, 1999

    USGS Publications Warehouse

    Pope, Larry M.; Bruce, Breton W.; Hansen, Cristi V.

    2001-01-01

    Water samples from 20 randomly selected domestic water-supply wells completed in the Quaternary deposits of south-central Kansas were collected as part of the High Plains Regional Ground-Water Study conducted by the U.S. Geological Survey's National Water-Quality Assessment Program. The samples were analyzed for about 170 water-quality constituents that included physical properties, dissolved solids and major ions, nutrients and dissolved organic carbon, trace elements, pesticides, volatile organic compounds, and radon. The purpose of this study was to provide a broad overview of ground-water quality in a major geologic subunit of the High Plains aquifer. Water from five wells (25 percent) exceeded the 500-milligrams-per-liter of dissolved solids Secondary Maximum Contaminant Level for drinking water. The Secondary Maximum Contaminant Levels of 250 milligrams per liter for chloride and sulfate were exceeded in water from one well each. The source of these dissolved solids was probably natural processes. Concentrations of most nutrients in water from the sampled wells were small, with the exception of nitrate. Water from 15 percent of the sampled wells had concentrations of nitrate greater than the 10-milligram-per-liter Maximum Contaminant Level for drinking water. Water from 80 percent of the sampled wells showed nitrate enrichment (concentrations greater than 2.0 milligrams per liter), which is more than what might be expected for natural background concentrations. This enrichment may be the result of synthetic fertilizer applications, the addition of soil amendment (manure) on cropland, or livestock production. Most trace elements in water from the sampled wells were detected only in small concentrations, and few exceeded respective water-quality standards. Only arsenic was detected in one well sample at a concentration (240 micrograms per liter) that exceeded its proposed Maximum Contaminant Level (5.0 micrograms per liter). Additionally, one concentration of iron and two concentrations of manganese were larger than the Secondary Maximum Contaminant Levels of 300 and 50 micrograms per liter, respectively. Some occurrences of trace elements may have originated from human-related sources; however, the generally small concentrations that were measured probably reflect mostly natural sources for these constituents. A total of 47 pesticide compounds from several classes of herbicides and insecticides that included triazine, organophosphorus, organochlorine, and carbamate compounds and three pesticide degradation products were analyzed in ground-water samples during this study. Water from 50 percent of the wells sampled had detectable concentrations of one or more of these 47 compounds. The herbicide atrazine and its degradation product deethylatrazine were detected most frequently (in water from eight and nine wells, respectively); other pesticides detected were the insecticides carbofuran (in water from one well) and diazinon (in water from one well), and the herbicide metolachlor (in water from two wells). However, all concentrations of these compounds were small and substantially less than established Maximum Contaminant Levels. The use of pesticides in crop production probably is largely responsible for the occurrence of pesticides in the ground-water samples collected during this study. Although concentrations of detected pesticides were small (relative to established Maximum Contaminant Levels), the synergistic effect of these concentrations and long-term exposure to multiple pesticides on human health are unknown. Water samples from the Quaternary deposits were analyzed for 85 volatile organic compounds. Water from two wells (10 percent) had a detectable concentration of a volatile organic compound. Chloroform was detected at concen-trations of 0.18 and 0.25 microgram per liter, substantially less than the 100-microgram-per-liter Maximum Contaminant Level for total trihalomethanes. In general, the occurrence and detectio

  9. Holocene flood plain soil formation in the lower Mississippi River Valley: Implications for the interpretation of alluvial paleosols

    SciTech Connect

    Aslan, A. (Univ. of Colorado, Boulder, CO (United States). Dept. of Geological Sciences); Autin, W.J. (Louisiana Geological Survey, Baton Rouge, LA (United States))

    1992-01-01

    Holocene Mississippi River flood soils representing different depositional environments and ages were sampled along three east-west transects between Vicksburg, MS and Baton Rouge, LA. Flood plain soil development is primarily controlled by episodic flood plain sedimentation and ground water table fluctuations as evidenced by relatively thick cumulative soil profiles with abundant mottles, nodules, and slickensides. Within flood plain deposits of similar age, profile, development is best expressed in moderately-drained silty and sandy soils in natural levee and point bar ridge environmental that occur within and adjacent to meander belts. Soils in natural levee and point bar ridge environments greater than 3 ka generally are acidic and have better-developed Bt horizons and brighter mottles than their younger counterparts. In addition to being acidic and brightly mottled, older back swamp soils have larger and more abundant slickensides and iron nodules. This study suggests that alluvial paleosols formed in aggradational settings may be better suited for interpreting flood plain depositional histories and paleohydrology than climate. Parameters such as solum thickness and clay and carbonate accumulations, routinely used to estimate relative time and climatic effects on soil development in Quaternary studies of stable geomorphic surfaces, may not be applicable to ancient alluvial deposits that reflect continuous sediment aggradation.

  10. Ochotona(Lagomorpha) from Late Quaternary Cave Deposits in Eastern North America

    NASA Astrophysics Data System (ADS)

    Mead, Jim I.; Grady, Frederick

    1996-01-01

    Pikas ( Ochtona)—small gnawing mammals, related to rabbits—range today throughout parts of the Northern Hemisphere, but had a wider distribution during the Pleistocene. Nine caves from northeastern North America (a region not occupied by pikas today) have Pleistocene deposits containing remains of Ochotona.We examine 526 fossil specimens (ranging in age from approximately 850,000 to 8670 yr B.P.) from five of these caves. Two morphological forms of Ochotonalived in northeastern North America during the late Pleistocene—a large species (probably O. whartoni) and a small species (probably O. princeps). Ochotonaof glacial age are not necessarily indicative of talus slopes and mesic communities. O. princeps-like of the Irvingtonian of West Virginia were living with an amphibian-reptilian assemblage found in the area today, implying winters not much, if at all, colder than at present. Late glacial and postglacial change in climate south of the ice sheets in effect would have isolated Ochotonain eastern North America, where they were unable to retreat to the west or north. Whereas western pika had the option of moving up in elevation, into boreal islands, eastern forms became restricted to ever-diminishing habitats, culminating in extinction and extirpation. Radiocarbon ages imply that Ochotonalived in eastern North America during the late Pleistocene (late Rancholabrean) and into the earliest Holocene. We describe the youngest remains of Ochotonain eastern North America and the youngest for the extinct large form, O. whartoni.

  11. Quaternary deposit control additives

    SciTech Connect

    Campbell, C.B.

    1986-01-14

    This patent describes a fuel's composition consisting of a major portion of hydrocarbons, which boils in the gasoline range, and from 30-10,000 ppm of a quaternized polyoxyalkylene amine salt of molecular weight 500-2500. This polyoxyalkylene moiety is characterized as consisting of 1-30 oxyalkylene units with 2-4 carbon atoms apiece. The aforementioned amine moiety consists of 1-2 amine nitrogen atoms and from about 2-40 carbon atoms. In addition, the fuel is characterized as containing a connecting moiety linking the polyoxyalkylene moiety and the amine moiety and within which the anion of the quaternized polyoxylakylene amine salts is composed of either chloride, bromide, or iodide.

  12. Quaternary deposit control additives

    SciTech Connect

    Campbell, C.B.

    1986-04-08

    This patent describes a lubricating oil composition. These additives consist of a major portion of an oil of lubricating viscosity and a dispersant effective amount of quaternized polyoxyalkylene amine salt additive of molecular weight from about 500 to about 2500. The polyoxyalkylene moiety consists of 1 to 30 oxyalkylene units selected from oxyalkylene units having 2 to 4 carbon atoms. The amine moiety consists of from 1 to about 12 amine nitrogen atoms and from about 2 to 40 carbon atoms, and further consisting of a connecting moiety linking the polyoxyalkylene moiety and the amine moiety.

  13. Sediment budget of Pliocene and Quaternary unconsolidated deposits of the Rhine Glacier area, Swiss Midlands and the Upper Rhine Graben

    Microsoft Academic Search

    J. Lämmermann-Barthel; I. Neeb; M. Hinderer; D. Ellwanger

    2003-01-01

    The Pliocene and Quaternary unconsolidated rocks of the Alpenrhein valley \\/ Bodensee amphitheatre, Hochrhein, Swabian terrace landscape, Swiss Midlands and the Upper Rhine Graben together with its Alpine drainage areas represent an almost closed denudation-accumulation system. Based on a newly developed combined stratigraphy valid in all five landsystems and an extensive data base (e.g. drillings, outcrop studies, mapping, seismics, pollen

  14. Mohawk Lake or Mohawk meadow Sedimentary facies and stratigraphy of Quaternary deposits in Mohawk Valley, upper Middle Fork of the Feather River, California

    SciTech Connect

    Yount, J.C. (Univ. of Nevada, Reno, NV (United States)); Harwood, D.S. (Geological Survey, Menlo Park, CA (United States)); Bradbury, J.P. (Geological Survey, Denver, CO (United States))

    1993-04-01

    Mohawk Valley (MV) contain thick, well-exposed sections of Quaternary basin-fill sediments, with abundant interbedded tephra and a diverse assemblage of sedimentary facies. The eastern arm of MV, extending from Clio to Portola, contains as much as 100 m of trough cross-bedded cobble to pebble gravel and planar and trough cross-bedded coarse and medium sand, interpreted as braided stream deposits. Sections exposed in the western arm of MV consist in their lower parts of massive organic-rich silt and clay interbedded with blocky to fissile peat beds up to 1 m thick. Diatom assemblages are dominated by benthic species indicating fresh marsh environments with very shallow water depths of one meter or less. Proglacial lacustrine deposits of limited lateral extent are present within the outwash complexes as evidenced by varved fine sand and silt couplets, poorly sorted quartz-rich silt beds containing dropstones, and contorted beds of diamict grading laterally into slump blocks surrounded by wood-bearing silt and silty sand. The Rockland Ash (400 ka) is a prominent marker in the middle or lower part of many sections throughout MV, indicating that at least half of the basin-fill sequence is Late Quaternary in age. A log buried in diamict slumped into a proglacial lake lying approximately 3 km downstream from the Tioga Stage ice termini in Jamison and Gray Eagle Creeks yields an age of 18,715 [+-]235 C[sup 14] years BP. Previous interpretations of MV deposits originating in a large, deep lake with water depths in excess of 150 m are untenable given the sedimentary facies and diatom floras that dominate the valley. Unexhumed valleys such as Sierra Valley to the east and Long Valley to the northwest which contain large meadows traversed by braided streams are probably good analogs for the conditions that existed during the accumulation of the Mohawk Valley deposits.

  15. Changes of chromium concentration in alluvial sediments of the Obra river valley

    Microsoft Academic Search

    Z. Mlynarczyk; T. Sobczynski; M. Slowik

    2006-01-01

    In this research work, changes in concentration of the chosen chemical element in alluvial sediments have been used to estimate the relative age of floodplain deposits. The research concerning changes of chromium concentration in alluvial deposits was done in the Obra river valley near Mi?dzyrzecz (Western Poland). Chromium was chosen because of its low ability to migrate in groundwater environment.

  16. High-resolution 3D seismic reflection and coring techniques applied to late Quaternary deposits on the New Jersey shelf

    Microsoft Academic Search

    Thomas A. Davies; James A. Austin

    1997-01-01

    Studies of variable, small-scale features typical of Quaternary glacimarine environments require an interdisciplinary approach: precisely navigated, high-resolution 3D seismic surveys nested within a regional 2D seismic framework and integrated with a precisely navigated coring program designed to sample specific shallow acoustic facies. We illustrate this approach with examples from continuing studies of sediments on the New Jersey continental shelf. Surficial

  17. Provenance of the heavy mineral-enriched alluvial deposits at the west coast of the Red Sea. Implications for evolution of Arabian-Nubian crust

    NASA Astrophysics Data System (ADS)

    Mahar, Munazzam Ali; Ibrahim, Tarek M. M.; Goodell, Philip C.

    2014-12-01

    Here we present the LA-ICP-MS U-Pb ages and Hf isotopic record of detrital zircons from the active alluvial fans at the west coast of the Red Sea. The Ras Manazal alluvial fan (primarily composed of zircon, magnetite with some rutile, ilmenite and monazite) yielded a relatively restricted age population ranges from 765 to 666 Ma. These ages and present-day drainage pattern is consistent that the sediments are primarily derived from erosion of nearby subduction related granitoids in the immediate west (i.e., not more than 50 km from the Red Sea coast) of the fan. In contrast, approximately 160 km south, at the Egypt-Sudan border, the Wadi Diit fan is relatively more enriched in ilmenite and REE-bearing phases (e.g., thorite, monazite, xenotime, garnet, etc.) and yielded five zircon age populations of (1) 824-733 Ma, (2) 730-705 Ma, (3) 646-608 Ma, (4) 516-500 Ma, and (5) 134-114 Ma. The age populations 1-3 if coupled with the present-day drainage pattern can be related to the earlier subduction related and later post collision granitoids in the southern part of the South Eastern Desert and Gebeit terrane of northern Sudan. Sparse Early Cretaceous zircons (134-114 Ma) are derived from the Mesozoic volcanic suits in the source region. However, the age group 516-500 Ma is enigmatic. Wadi Diit zircons are primarily derived from granitoids in the broad S-N directed Hamisana Shear Zone and its subordinate SW to NE directed Onib-Sol-Hamed Suture Zone. These shear zones provided pathways for the present-day drainage system for sediment transportation to the Wadi Diit and adjacent coastal region. We infer that the ca. 500 Ma late-stage magmatic zircons represent a hitherto unknown magmatic event, possibly related to the shear heating associated with the crustal scale shear zones. This implies that the shear zones in the South Eastern Desert and northern Sudan remained thermally active as late as ?500 Ma. The time resolved hafnium composition (?Hf (t)) of both fans varies from +3.5 to +13.5. Our new U-Pb ages and Hf isotopic composition suggests that the detrital zircons were derived from the Neoproterozoic juvenile crust. This is consistent with the Neoproterozoic juvenile igneous and metamorphic rocks in the Eastern Desert and northern Sudan.

  18. Provenance of the Heavy Mineral-enriched Alluvial Deposits at the West Coast of Red Sea. Implications to the Evolution of Arabian-Nubian Crust

    NASA Astrophysics Data System (ADS)

    Mahar, M. A.; Ibrahim, T.; Goodell, P.

    2014-12-01

    Here we present the LA-ICP-MS U-Pb ages and Hf isotopic record of detrital zircons from the active alluvial fans at the west coast of the Red Sea. The Ras Manazal alluvial fan (primarily composed of zircon, magnetite with some rutile, ilmenite and monazite) yielded a relatively restricted age population ranges from 765 to 666 Ma. These ages and present-day drainage pattern is consistent that the sediments are primarily derived from erosion of nearby subduction related granitoids in the immediate west (i.e., not more than 50 km from the Red Sea coast) of the fan. In contrast, approximately 160 km south, at the Egypt-Sudan border, the Wadi Diit fan is relatively more enriched in ilmenite and REE-bearing phases (e.g., thorite, monazite, xenotime, garnet etc.) and yielded five zircon age populations of 1) 824-733 Ma, 2) 730-705 Ma, 3) 646-608 Ma, 4) 516-500 Ma, and 5) 134-114 Ma. The age populations 1-3 if coupled with the present-day drainage pattern can be related to the earlier subduction related and later post collision granitoids in the southern part of the South Eastern Desert and Gebeit terrane of northern Sudan. Sparse Early Cretaceous zircons (134-114 Ma) are derived from the Mesozoic volcanic suits in the source region. However, the age group 516-500 Ma is enigmatic. Wadi Diit zircons are primarily derived from granitoids in the broad S-N directed Hamisana Shear Zone and its subordinate SW to NE directed Onib-Sol-Hamed Suture Zone. These shear zones provided pathways for the present-day drainage system for sediment transportation to the Wadi Diit and adjacent coastal region. We infer that the ca. 500 Ma late-stage magmatic zircons represent a hitherto unknown magmatic event, possibly related to the shear heating associated with the crustal scale shear zones. This implies that the shear zones in the South Eastern Desert and northern Sudan remained thermally active as late as ~500 Ma. The time resolved hafnium composition (?Hf (t)) of both fans varies from +3.5 to +13.5. Our new U-Pb ages and Hf isotopic composition suggests that the detrital zircons were derived from the Neoproterozoic juvenile crust. This is consistent with the Neoproterozoic juvenile igneous and metamorphic rocks in the Eastern Desert and northern Sudan.

  19. Hydrogeologic Framework and Ground-Water Flow in Quaternary Deposits at the U.S. Army Atterbury Joint Maneuver Training Center near Edinburgh, Indiana, 2002-2003

    USGS Publications Warehouse

    Robinson, Bret A.; Risch, Martin R.

    2006-01-01

    A hydrogeologic framework was developed for unconsolidated Quaternary deposits at the U.S. Army Atterbury Joint Maneuver Training Center. The framework describes the potential for the occurrence of ground water on the basis of physiography and the distribution of geologic materials within the study area. Four geologic units-the Jessup, Trafalgar, Atherton, and Martinsville Formations-were identified, and their distribution was mapped as four hydrogeologic regions. The Jessup and Trafalgar Formations are fine-grained, poorly sorted tills. At least two facies of the Atherton Formation, the lacustrine and outwash facies, are in the study area. The Martinsville Formation includes materials deposited or reworked since the glacial period. With the exception of the Atherton Formation outwash facies, the Quaternary deposits are primarily fine-grained, silt- and clay-rich sediments that function as confining layers or aquitards. The Atherton Formation out-wash facies includes sand and gravel deposits that constitute the primary aquifers in the study area. The four hydrogeologic regions mapped in this investigation are designated as the Bedrock, Jessup Till, Trafalgar Till, and Atherton Outwash Regions. Each region represents an area with a distinctive physiographic expression and vertical sequence of Quaternary deposits. The Bedrock Region in the western and southwestern part of the study area commonly is underlain by 0 to 15 feet of Martinsville Formation resting directly on bedrock. Potential ground-water yields are limited. The Jessup Till Region in the southeastern part of the study area includes the uplands on either side of the stream valleys. Sediments commonly range from 30 to 90 feet in thickness. This region includes clay-rich till of the Jessup Formation and sand and gravel deposits of the Atherton Formation outwash facies; the Atherton Formation outwash facies tends to be thin, and ground-water yields will be moderate. The Trafalgar Till Region in the north and northwest-central part of the study area commonly is underlain by 10 to 30 feet of Trafalgar till or Trafalgar till over 25 to 50 feet of Jessup till. Within, separating, and beneath these tills are deposits of the Atherton Formation outwash facies-the sand and gravel deposits with the best potential to support a water-supply well. Generally, the outwash facies in this region are thin sand and gravel lenses, except in a few locations that are in excess of 30 feet thick. The Atherton Outwash Region is the lowland area associated with the major valleys in all but the far southwestern part of the study area. This region has the greatest thickness of outwash facies sands and gravels (often in excess of 20 feet), which are the primary aquifers. In the Atterbury Joint Maneuver Training Center, the combined Atherton Outwash Region and the Trafalgar Till Region have the greatest potential as infiltration areas because of low topographic relief and(or) sandy soils. From water-level data collected in July and August 2003, horizontal ground-water flow was determined generally to be toward the Atherton Outwash Region and the valley of the Drift-wood River to the east. Vertical hydraulic gradients were documented at nested well pairs. At two sites, upwardly directed gradients are reflected by flowing wells. Ground-water discharge to surface water is likely in some eastern reaches of the valleys of Nineveh and Lick Creeks. In the valley of Nineveh Creek, potential for ground-water discharge is indicated by the presence of a flowing well, upwardly directed vertical hydraulic gradients, and ground-water heads that were higher than surface-water elevations. In the valley of Lick Creek, ground-water discharge also is indicated by the presence of flowing wells and ground-water heads that were higher than surface-water elevations.

  20. Quaternary Studies

    NSDL National Science Digital Library

    First, the Irish Quaternary Association (IQUA) website publicizes its aim "to promote Quaternary studies in Ireland through its publications, and the organization of field meetings and conferences" (1). Visitors can learn about the importance of quaternary studies as well as find out the latest news and upcoming meetings. At the second website, the University of Wisconsin-Madison describes the current and recent studies dealing with "basic and applied problems in glacial geology, surficial geology, palynology, sedimentology, geologic mapping, hydrogeology, soils, and environmental geology "(2). The website offers abstracts of publications of members of the Department of Geology and Geophysics and the Wisconsin Geological and Natural History Survey along with descriptions of the lab, a shaded relief map of the Wisconsin area, and amusing glacial songs. Next, the Godwin Institute of Quaternary Research (GIQR) presents the University of Cambridge's history in quaternary research and the seven current research groups and four recent research projects (3 ). The website furnishes news from the research groups, a gallery of historical images of the East Anglia excursion, and summaries of the Institute's reference collections. Fourth, the International Union for Quaternary Research (INQUA) discusses quaternary scientists' investigations "to interpret the changing world of the glacial ages and their impact on our planet's surface environments" (4). Researchers can find out about INQUA-funded projects, meetings, and scientific commissions. Next, the Quaternary Research Association explains that it "exists to promote understanding of the Quaternary Period by publishing field guides, technical guides, and an international journal as well as holding field meetings and speaker meetings" (5). Students and researchers can discover employment, research, grant, meetings, and educational opportunities. Sixth, the University of Wales presents its investigations in the Remote Sensing Laboratory, Palaeoecology Laboratory, and the Luminescence Laboratory (6 ). Users can find concise descriptions of individual researchers' successes, abstracts of published papers, and links to conference information. The seventh website illustrates the Alaska Quaternary Center's commitment "to the promotion of interdisciplinary research and the enhancement of interdisciplinary instruction in Quaternary sciences" (7). Users can view images of the field work and learn how to obtain quaternary data from the Geographic Information Network of Alaska (GINA). Lastly, Rutgers University promotes its Graduate Certificate in Quaternary Studies where students take part in geology, geography, meteorology, and other disciplines interested in the last couple of million years of Earth's history (8). Students and educators can find information on the researchers involved with the program and the necessary course work.

  1. Sedimentology and depositional history of Neogene gravel deposits in lower Tornillo Creek area of Big Bend National Park, Texas

    SciTech Connect

    Thurwachter, J.E.

    1984-04-01

    Neogene gravel deposits in the lower Tornillo Creek area of Big Bend National Park, Texas, record the filling of a small structural basin formed during Basin and Range tectonism. Four lithofacies are recognized in the Late Miocene La Noria member (informal name): (1) a medial braided-stream lithofacies consisting of upward-fining packages of cross-bedded gravel, sandstone, and siltstone; (2) a distal braided-stream lithofacies consisting of poorly-defined upward-fining packages of fine gravel, sandstone, and mudstone; (3) a calcrete-rich gravel and sandstone lithofacies representing strike-valley and alluvial-fan deposition, and (4) and ephemeral lake-plain lithofacies consisting of massive and burrowed mudstones with sheet-like sandstone interbeds. Upward-fining packages in the braided-stream lithofacies represent the lateral migration and avulsion of the stream tract across the basin; together with the strike-valley and alluvial-fan deposits, these record the initial stages of basin filling. Provenance studies show that much of this sediment was derived from northern Mexico. Overlying ephemeral-lake deposits record the structural tilting and closing of the downstream (north) end of the basin. Gravels and minor sandstones of the Pleistocene Estufa member (informal name) represent basinward progradation of alluvial fans. Deposition of the Estufa member resulted from: (1) Quaternary tectonic activity in the Chisos Mountains area; (2) lowering of local base level by post-Miocene development of the Rio Grande drainage through the area; and (3) Pleistocene pluvial-period climatic changes. Subsequent Quaternary faulting has caused minor deformation of the deposits.

  2. Alluvial Soil Chronosequence in the Inner Coastal Plain, Central Virginia

    NASA Astrophysics Data System (ADS)

    Howard, Jeffrey L.; Amos, Dan F.; Daniels, W. Lee

    1993-03-01

    A chronological sequence of soils formed on a series of alluvial depositional surfaces ranging in age from late-middle Miocene to late Pleistocene was characterized to clarify soil-geomorphic relations and provide a basis for allostratigraphic subdivision of the inner Coastal Plain. On Quaternary river terraces, Ultic Hapludalfs containing abundant weatherable mineral species and clast types are estimated to have formed in 60,000-120,000 yr, whereas Typic Hapludults greatly depleted in weatherable minerals and showing strong weathering of clast types are estimated to be 700,000-1,600,000 yr old. Typic Paleudults with incipient plinthite, duripan, and ferricrete development characterize interfluves that have been little eroded since early Pliocene time (3.4-5.3 myr ago). Typic-Plinthic Paleudults with intense weathering of siliceous clasts and moderate to strong duripan and ferricrete development are found on surfaces that formed near the beginning of late Miocene time (10.8-13.0 myr ago). Chemical weathering in the chronosequence may be classified into three progressive stages: (1) decomposition of unstable sand- and silt-sized minerals into a mixed (stable + unstable) clay-mineral suite (stable Fe + Al/Si bulk chemical composition, < 10 6 yr); (2) transformation of mixed clay-mineral suite into a stable suite (increasing Fe + Al/Si bulk chemical composition, 10 6 - 10 7 yr); and (3) transformation of stable suite into ultrastable clay-mineral suite (increasing Fe/Si bulk composition, > 10 7 yr). Not all soil properties show unidirectional development, nor is a steady state of pedon development observed even after approximately 10 7 yr of chemical weathering. Soil development in the chronosequence is episodic. The transition from one phase to the next is marked by a change in rate, and sometimes a reversal in the direction, of development of one or more soil properties.

  3. High-resolution sequence stratigraphy of an alluvial fan–fan delta environment: stratigraphic and geodynamic implications – An example from the Keuper Chaunoy Sandstones, Paris Basin

    Microsoft Academic Search

    Sylvie Bourquin; Christophe Rigollet; Philippe Bourges

    1998-01-01

    Facies analysis of the Chaunoy Formation, conducted as the first stage of this study, reveals that the corresponding fluvial system essentially involved bedload deposition, 2-D and 3-D megaripple migration, and debris-flow deposition. Such processes are characteristic of alluvial fan depositional environments. These alluvial fan deposits pass laterally eastward into a shallow lacustrine environment. In stage 2 of the study, electrofacies

  4. A debris flow deposit in alluvial, coal-bearing facies, Bighorn Basin, Wyoming, USA: Evidence for catastrophic termination of a mire

    USGS Publications Warehouse

    Roberts, S.B.; Stanton, R.W.; Flores, R.M.

    1994-01-01

    Coal and clastic facies investigations of a Paleocene coal-bearing succession in the Grass Creek coal mine, southwestern Bighorn Basin, Wyoming, USA, suggest that disruption of peat accumulation in recurrent mires was caused by the repetitive progradation of crevasse splays and, ultimately, by a catastrophic mass movement. The mass movement, represented by deposits of debris flow, marked the termination of significant peat accumulation in the Grass Creek coal mine area. Megascopic and microscopic analyses of coal beds exposed along the mine highwalls suggest that these deposits developed in low-lying mires, as evidenced primarily by their ash yields and maceral composition. Disruption of peat accumulation in successive mires was caused by incursions of sediment into the mire environments. Termination by crevasse splay progradation is represented by coarsening-upward successions of mudrock and tabular, rooted sandstone, which overlie coal beds in the lower part of the coal-bearing interval. A more rapid process of mire termination by mass movement is exemplified by a debris flow deposit of diamictite, which overlies the uppermost coal bed at the top of the coal-bearing interval. The diamictite consists of a poorly sorted, unstratified mixture of quartzite cobbles and pebbles embedded in a claystone-rich or sandy mudstone matrix. Deposition of the diamictite may have taken place over a matter of weeks, days, or perhaps even hours, by catastrophic flood, thus reflecting an instantaneous process of mire termination. Coarse clastics and mud were transported from the southwest some 20-40 km as a viscous debris flow along stream courses from the ancestral Washakie Range to the Grass Creek area, where the flow overrode a low-lying mire and effectively terminated peat accumulation. ?? 1994.

  5. Lidar-Based Mapping of Late Quaternary Faulting Along the Grizzly Valley Fault, Walker Lane Seismic Belt, California

    NASA Astrophysics Data System (ADS)

    Hitchcock, C. S.; Hoirup, D. F.; Barry, G.; Pearce, J.; Glick, F.

    2012-12-01

    The Grizzly Valley fault (GVF) is located within the northern Walker Lane, a zone of right-lateral shear between the Sierra Nevada and the Basin and Range in Plumas County. The GVF extends southeasterly from near Mt. Ingalls along the eastern side of Lake Davis. It may partially connect with the Hot Creek fault within Sierra Valley and extend south to Loyalton with an overall approximate length of 50 km. Comparison of high-resolution topography developed from LiDAR data with published bedrock geologic mapping documents the presence of geomorphic features that provide information on fault activity of the GVF. Field mapping verified tectonically deformed and offset late Quaternary surfaces identified on bare-earth LiDAR imagery across the GVF within glacial deposits on the eastern margin of Lake Davis, and alluvial deposits in Sierra Valley. Along the GVF, conspicuous geomorphic and hydrologic features include scarps in alluvial surfaces, elongated depressions aligned with adjacent linear escarpments, truncated bedrock spurs, closed depressions, linear swales, right-lateral deflections of creeks and river courses, and shutter ridges, as well as springs and linear seeps consistent with right-lateral strike-slip faulting. The discontinuous nature of observed fault traces combined with the apparent down-to-the-west offset of alluvial surfaces at the southern and northern ends of the eastern margin of Lake Davis are consistent with a broad bend or step over in the fault. Scarp profiles of apparently faulted surfaces extracted from LiDAR data document vertical offsets of up to 14 m. Our study suggest that the GVF is an oblique, right-lateral fault that has been active in the late Quaternary. This study complements on-going investigations by DWR to assess the impact of seismic hazards on State Water Project infrastructure.

  6. The “Alluvial Mesovoid Shallow Substratum”, a New Subterranean Habitat

    PubMed Central

    Ortuño, Vicente M.; Gilgado, José D.; Jiménez-Valverde, Alberto; Sendra, Alberto; Pérez-Suárez, Gonzalo; Herrero-Borgoñón, Juan J.

    2013-01-01

    In this paper we describe a new type of subterranean habitat associated with dry watercourses in the Eastern Iberian Peninsula, the “Alluvial Mesovoid Shallow Substratum” (alluvial MSS). Historical observations and data from field sampling specially designed to study MSS fauna in the streambeds of temporary watercourses support the description of this new habitat. To conduct the sampling, 16 subterranean sampling devices were placed in a region of Eastern Spain. The traps were operated for 12 months and temperature and relative humidity data were recorded to characterise the habitat. A large number of species was captured, many of which belonged to the arthropod group, with marked hygrophilous, geophilic, lucifugous and mesothermal habits. In addition, there was also a substantial number of species showing markedly ripicolous traits. The results confirm that the network of spaces which forms in alluvial deposits of temporary watercourses merits the category of habitat, and here we propose the name of “alluvial MSS”. The “alluvial MSS” may be covered or not by a layer of soil, is extremely damp, provides a buffer against above ground temperatures and is aphotic. In addition, compared to other types of MSS, it is a very unstable habitat. It is possible that the “alluvial MSS” may be found in other areas of the world with strongly seasonal climatic regimes, and could play an important role as a biogeographic corridor and as a refuge from climatic changes. PMID:24124544

  7. Controls on alluvial fan long-profiles

    USGS Publications Warehouse

    Stock, J.D.; Schmidt, K.M.; Miller, D.M.

    2008-01-01

    Water and debris flows exiting confined valleys have a tendency to deposit sediment on steep fans. On alluvial fans where water transport of gravel predominates, channel slopes tend to decrease downfan from ???0.10-0.04 to ???0.01 across wide ranges of climate and tectonism. Some have argued that this pattern reflects grain-size fining downfan such that higher threshold slopes are required just to entrain coarser particles in the waters of the upper fan, whereas lower slopes are required to entrain finer grains downfan (threshold hypothesis). An older hypothesis is that slope is adjusted to transport the supplied sediment load, which decreases downfan as deposition occurs (transport hypothesis). We have begun to test these hypotheses for alluvial fan long-profiles using detailed hydraulic and particle-size data in sediment transport models. On four alluvial fans in the western U.S., we find that channel hydraulic radiiare largely 0.5-0.9 m at fan heads, decreasing to 0.1-0.2 m at distal margins. We find that median gravel diameter does not change systematically along the upper 60%-80% of active fan channels as slope declines, so downstream gravel fining cannot explain most of the observed channel slope reduction. However, as slope declines, channel-bed sand cover increases systematically downfan from areal fractions of <20% above fan heads to distal fan values in excess of 70%. As a result, entrainment thresholds for bed material might decrease systematically downfan, leading to lower slopes. However, current models of this effect alone tend to underpredict downfan slope changes. This is likely due to off-channel gravel deposition. Calculations that match observed fan long-profiles require an exponential decline in gravel transport rate, so that on some fans approximately half of the load must be deposited off channel every -0.20-1.4 km downfan. This leads us to hypothesize that some alluvial fan long-proffies are statements about the rate of overbank deposition of coarse particles downfan, a process for which there is currently no mechanistic theory. ?? 2007 Geological Society of America.

  8. Neogene-Quaternary depositional history of the eastern US continental rise seaward of the Washington-Norfolk Canyon systems

    SciTech Connect

    Locker, S.D.; Laine, E.P.

    1985-01-01

    High quality, digitally recorded and processed, water gun and air gun seismic reflection data collected seaward of the present position of the Washington-Norfolk canyon systems reveals new information on the development of the continental rise. This includes insight into the depositional history of the Washington-Norfolk fan system and the relative importance of gravity flow depositional processes versus abyssal bottom current reworking during rise development. Three major post-Horizon A/sup u/ accretionary sequences describe major changes in depositional processes and history within the region. Accretionary sequence I (early to middle Miocene) is characterized by the initial development of a depositional bulge seaward of the Washington-Norfolk canyon systems which is modified by bottom currents on the lower-most rise to form a proto-Hatteras Outer Ridge. The predominance of chaotic and hummocky seismic facies suggests widespread reworking by abyssal bottom currents. Accretionary sequence II (middle Miocene to late Pliocene) in this area is characterized by sediment waves (lower rise) and smooth, southward dipping, parallel reflectors associated with a thick central rise drift(.) deposit off the Hudson system to the North. Washington-Norfolk fan development appears less important during this time. Bottom currents are active, but more depositional in nature than during accretionary sequence I. Accretionary sequence III (late Pliocene to Present) is marked by gravity flow processes and distinct development of the Washington-Norfolk fan on the central rise.

  9. Quantities and associations of lead, zinc, cadmium, manganese, chromium, nickel, vanadium, and copper in fresh Mississippi delta alluvium and New Orleans alluvial soils

    Microsoft Academic Search

    H. W. Mielke; C. R. Gonzales; M. K. Smith; P. W. Mielke

    2000-01-01

    The topic of this study is the effect of anthropogenic metals on the geochemical quality of urban soils. This is accomplished by comparing the metal contents and associations between two alluvial soils of the lower Mississippi River Delta, freshly deposited alluvial parent materials and alluvial soils collected from a nearby urban environment. Fresh alluvium samples (n=97) were collected from the

  10. Soil genesis on the island of Bermuda in the Quaternary: the importance of African dust transport and deposition

    USGS Publications Warehouse

    Muhs, Daniel R.; Budahn, James R.; Prospero, Joseph M.; Skipp, Gary; Herwitz, Stanley R.

    2012-01-01

    The origin of terra rossa, red or reddish-brown, clay-rich soils overlying high-purity carbonate substrates, has intrigued geologists and pedologists for decades. Terra rossa soils can form from accumulation of insoluble residues during dissolution of the host limestones, addition of volcanic ash, or addition of externally derived, long-range-transported (LRT) aeolian particles. We studied soils and paleosols on high-purity, carbonate aeolianites of Quaternary age on Bermuda, where terra rossa origins have been debated for more than a century. Potential soil parent materials on this island include sand-sized fragments of local volcanic bedrock, the LRT, fine-grained (N/YbN, GdN/YbN that can be distinguished from African dust and lower Mississippi River valley loess. Bermuda soils have Sc-Th-La, Cr-Ta-Nd, and Eu/Eu*, LaN/YbN, GdN/YbN that indicate derivation from a combination of LRT dust from Africa and local volcanic bedrock. Our results indicate that soils on islands in a very broad latitudinal belt of the western Atlantic margin have been influenced by African LRT dust inputs over much of the past –500 ka.

  11. Late Quaternary extraglacial cold-climate deposits in low and mid-altitude Tasmania and their climatic implications

    NASA Astrophysics Data System (ADS)

    McIntosh, P. D.; Eberhard, R.; Slee, A.; Moss, P.; Price, D. M.; Donaldson, P.; Doyle, R.; Martins, J.

    2012-12-01

    Many Tasmanian deposits previously described as 'periglacial' have been described in more detail, re-interpreted and dated. We suggest that 'periglacial' has little meaning when applied locally and the term 'relict cold-climate deposits' is more appropriate. In this paper we examine the origin and age of relict cold-climate slope deposits, fan alluvium and aeolian sediments in Tasmania, and infer the conditions under which they accumulated. Fan alluvium dating from the penultimate Glacial (OIS 6) and capped by a prominent palaeosol deduced to date to the Last Interglacial (OIS 5e) is present at Woodstock, south of Hobart. Many fan deposits formed before 40 ka or in a period c. 30-23 ka; only a few deposits date to the Last Glacial Maximum in Tasmania, which is defined as spanning the period 23.5-17.5 ka. Slope deposits indicate widespread instability down to present-day sea level throughout the Last Glacial, probably as a result of freeze-thaw in a sparsely vegetated landscape. Layered fine gravel and coarse sand colluvial deposits resembling grèzes litées, produced both by dry deposition and by the action of water, are locally common where jointed siltstone bedrock outcrops. These deposits occur from altitudes of 500 m to near sea level and also in caves and must have formed under sparse vegetation cover, probably by freeze-thaw in extremely dry conditions. They have been radiocarbon dated from 35 to 17.5 cal. ka. Relict dunes and sandsheets are widespread at the margin of the Bassian Plain that once provided a land bridge between Tasmania and the mainland. They are also found in western Tasmania and in areas of inland southern Tasmania that now support wet eucalypt forest and rainforest and receive mean annual rainfall > 1500 mm. In the south they have been dated > 87.5-19 ka and attest to a long period of semi-arid climate in an area extending well to the west and south of the present semiarid zone. We deduce that during most of the Last Glacial anticyclones dominated Tasmania's climate and rain-bearing depressions generally passed south of the land mass. However in the east prominent palaeosols in aeolian deposits, dated between 26.4 ka and 16 ka at different locations, and palaeosols with morphology indicating formation under humid conditions, indicate periods of wetter climate in eastern Tasmania during or close to the LGM, deduced to be the result of easterlies associated with near-coastal depressions in the western Tasman Sea. Such easterlies may also be responsible for short Last Glacial wet periods noted at mainland coastal sites. A plot of ages of all dated deposits reveals an increase of erosion and deposition between 35 and 20 ka, and greater prevalence of aeolian deposits in the 35-15 ka period than earlier in the Last Glacial. There are two possible explanations for this pattern: (1) that aeolian activity increased as the result of climatic effects (e.g. increased windiness); or (2) that shrubland biomass increased after the megafauna were hunted to extinction following human arrival c. 40 ka, causing increased fire frequency, and in the cold dry climate of the late Last Glacial such fires caused increased erosion and increased aeolian accumulation.

  12. Morphotectonic, Quaternary and Structural Geology Analyses of the Shallow Geometry of the Mw 6.1, 2009 L'Aquila Earthquake Fault (central Italy): A Missed Opportunity for Surface Faulting Prevention.

    NASA Astrophysics Data System (ADS)

    Pucci, S.; Villani, F.; Civico, R.; Pantosti, D.; Smedile, A.; De Martini, P. M.; Di Naccio, D.; Gueli, A.

    2014-12-01

    The surface-rupturing 2009 L'Aquila earthquake evidenced the limited knowledge of active faults in the Middle Aterno Valley area. Gaps in detailed mapping of Quaternary deposits and tectonic landforms did not trigger researches on active faults, but after the tragic event. We present a morphotectonic study of geometry and evolution of the activated fault system (Paganica-San Demetrio, PSDFS). The LIDAR analysis and field survey yield to a new geological and structural map of the area with an unprecedented detail for the Quaternary deposits. It shows an alluvial depositional system prograding and migrating due to fault system evolution. The normal faults offset both the Quaternary deposits and the bedrock. The structural analysis allows us to recognize two fault systems: (A) NNE- and WNW-trending conjugate extensional system overprinting a strike-slip kinematics and (B) dip-slip NW-trending system. Crosscut relationship suggests that the activity of system B prevails, since Early Pleistocene, on system A, which earlier may have controlled a differently shaped basin. System B is the main responsible for the present-day compound outline of the Middle Aterno Valley, while system A major splays now act as segment boundaries. The long-term expression of B results in prominent fault scarps offsetting Quaternary deposits, dissecting erosional and depositional flat landforms. We retrieved detailed morphologic throws along fault scarps and we dated landforms by 14C, OSL (Optically Stimulated Luminescence), CRN (Cosmogenic Radionuclide) and tephra chronology. We show the persistent role of extensional faulting in dominating Quaternary landform evolution and we estimate slip-rate of the PSDFS at different time-scales. The results support repeated activity of PSDFS for ~20 km total length, thus implying M6.6 maximum expected earthquake. Such an approach should have been applied beforehand for the actual hazard estimation, to trigger, early enough, the adoption of precautionary measures against surface faulting events.

  13. Soil genesis on the island of Bermuda in the Quaternary: The importance of African dust transport and deposition

    NASA Astrophysics Data System (ADS)

    Muhs, Daniel R.; Budahn, James R.; Prospero, Joseph M.; Skipp, Gary; Herwitz, Stanley R.

    2012-09-01

    The origin of terra rossa, red or reddish-brown, clay-rich soils overlying high-purity carbonate substrates, has intrigued geologists and pedologists for decades. Terra rossa soils can form from accumulation of insoluble residues during dissolution of the host limestones, addition of volcanic ash, or addition of externally derived, long-range-transported (LRT) aeolian particles. We studied soils and paleosols on high-purity, carbonate aeolianites of Quaternary age on Bermuda, where terra rossa origins have been debated for more than a century. Potential soil parent materials on this island include sand-sized fragments of local volcanic bedrock, the LRT, fine-grained (<20?m) component of distal loess from the lower Mississippi River Valley, and LRT dust from Africa. These parent materials can be characterized geochemically using trace elements that are immobile in the soil-forming environment. Results indicate that local volcanic bedrock on Bermuda has Sc-Th-La, Cr-Ta-Nd, and Eu/Eu*, LaN/YbN, GdN/YbNthat can be distinguished from African dust and lower Mississippi River valley loess. Bermuda soils have Sc-Th-La, Cr-Ta-Nd, and Eu/Eu*, LaN/YbN, GdN/YbN that indicate derivation from a combination of LRT dust from Africa and local volcanic bedrock. Our results indicate that soils on islands in a very broad latitudinal belt of the western Atlantic margin have been influenced by African LRT dust inputs over much of the past ˜500 ka.

  14. Large alluvial fans on Mars

    Microsoft Academic Search

    Jeffrey M. Moore; Alan D. Howard

    2005-01-01

    Several dozen distinct alluvial fans, 10 to ?40 km long downslope, have been observed in highlands craters. Within a search region between 0° and 30°S, alluvial fan-containing craters were found only between 18° and 29°S, and they all occur at around ±1 km of the MOLA-defined Martian datum. Within the study area they are not randomly distributed but instead form

  15. Quaternary geology and geologic hazards of the West Desert Hazardous Industry Area, Tooele County, Utah

    USGS Publications Warehouse

    Solomon, Barry J.; Black, Bill D.

    1990-01-01

    The study of Quaternary geology provides information to evaluate geologic conditions and identify geologic constraints on construction in the West Desert Hazardous Industry Area (WDHIA). The WDHIA includes portions of the Great Salt Lake Desert to the west, underlain by several thousand feet of sediments capped by saline mudflats, and Ripple Valley to the east, separated from the Desert by the Grayback Hills and underlain by several hundred feet of sediments in the Cedar Mountains piedmont zone. Quaternary surficial units include marginal, shore-zone, and deep-water lacustrine sediments deposited in Pleistocene Lake Bonneville; eolian deposits; and alluvial sediments. The level of Lake Bonneville underwent major oscillations resulting in the creation of four basin-wide shorelines, three of which are recognized in the WDHIA. Geologic hazards in the WDHIA include the possible contamination of ground water in basin-fill aquifers, debris flows and flash floods in the piedmont zone, and earthquakes and related hazards. Numerous factors contribute to unsafe foundation conditions. Silty and sandy sediments may be subject to liquefaction or hydrocompaction, clayey sediments and mud flats of the Great Salt Lake Desert may be subject to shrinking or swelling, and gypsiferous dunes and salt flats are subject to subsidence due to dissolution.

  16. Late Quaternary depositional architecture of Po and Tevere river deltas (Italy) and worldwide comparison with coeval deltaic successions

    NASA Astrophysics Data System (ADS)

    Amorosi, Alessandro; Milli, Salvatore

    2001-11-01

    Po and Tevere rivers form two of the most important deltas of the whole Mediterranean area. Detailed investigations have been carried out in the last decade beneath the present delta plains of these two river systems using borehole data correlation. With the aid of radiocarbon dates and other dating methods (pollens, archaeology) a detailed sequence stratigraphic framework has been constructed in both areas, especially for the last glacial-interglacial cycle. Regional subsidence, combined with short-term sea-level fluctuations of relatively high amplitude, played a fundamental role in creating/subtracting accommodation during the long phase of falling sea level, which followed the Tyrrhenian (substage 5e) transgressive event. A discontinuous record of this phase is present in the subsurface of the Po Plain, whereas poor or no preservation has been detected in the Tevere area. Progradational lowstand wedges accumulated during the last glacial maximum mostly in the central part of the basins, far from the present deltas, and are lacking in the study areas, where a hiatal surface is invariably recorded below the transgressive deposits. Glacioeustasy exerted a major control on sedimentation in both areas during the latest Pleistocene-Holocene sea-level rise. Infilling of fluvial valleys and rapid landward migration of barrier-lagoon systems, in the context of wave-dominated estuaries, characterized the transgressive phase in both Po and Tevere systems. In-place drowning and transgressive submergence mechanisms of barrier migration were effective predominantly between 13.5 and 9 ka BP. In contrast, shoreface retreat was dominant in the late transgressive phase. The maximum flooding surface (MFS) can be traced physically from continental to marine deposits, and has similar characteristics in the Po and Tevere river systems, being marked by peat layers or lagoonal deposits at landward locations and by distinctive lithological characteristics and micro- and macrofossils assemblages basinwards. Above the MFS, the early highstand systems tract records initially the filling of the lagoons, followed by the rapid progradation of wave-dominate delta systems and flanking strandplains. Autocyclic processes, such as distributary channel avulsion, delta lobe abandonment, and local subsidence due to sediment compaction were the fundamental controlling factors on sedimentation during deposition of the HST. The stratigraphic architecture of the post-glacial Po and Tevere delta complexes closely resembles the basic facies successions documented from coeval deposits of wave-dominated and wave-influenced clastic coasts, both locally within the Mediterranean area and in other parts of the world. Our study emphasizes, however, some additional features and major differences with previously published depositional models, including (i) the development of backstepping wave-dominated estuaries during transgression; (ii) consistent changes through time in the mechanism of barrier migration; (iii) a later construction of the delta systems, with respect to what traditionally considered.

  17. Large alluvial fans on Mars

    NASA Astrophysics Data System (ADS)

    Moore, Jeffrey M.; Howard, Alan D.

    2005-04-01

    Several dozen distinct alluvial fans, 10 to ~40 km long downslope, have been observed in highlands craters. Within a search region between 0° and 30°S, alluvial fan-containing craters were found only between 18° and 29°S, and they all occur at around +/-1 km of the MOLA-defined Martian datum. Within the study area they are not randomly distributed but instead form three distinct clusters. Fans typically descend >1 km from where they disgorge from their alcoves. Longitudinal profiles show that their surfaces are very slightly concave with a mean slope of 2°. Many fans exhibit very long, narrow, low-relief ridges radially oriented downslope, often branching at their distal ends, suggestive of distributaries. Morphometric data for 31 fans were derived from MOLA data and compared with terrestrial fans with high-relief source areas, terrestrial low-gradient alluvial ramps in inactive tectonic settings, and older Martian alluvial ramps along crater floors. The Martian alluvial fans generally fall on the same trends as the terrestrial alluvial fans, whereas the gentler Martian crater floor ramps are similar in gradient to the low-relief terrestrial alluvial surfaces. For a given fan gradient, Martian alluvial fans generally have greater source basin relief than terrestrial fans in active tectonic settings. This suggests that the terrestrial source basins either yield coarser debris or have higher sediment concentrations than their Martian counterpoints. Martian fans (and terrestrial Basin and Range fans) have steeper gradients than the older Martian alluvial ramps (and terrestrial low-relief alluvial surfaces), which is consistent with the construction of Martian fans from dominantly gravel-sized sediment (rather than sand and silt). Martian fans are relatively large and of low gradient, similar to terrestrial fluvial fans rather than debris flow fans (although gravity-scaling uncertainties make the flow regime forming Martian fans uncertain). However, evidence of bedforms accentuated by differential erosion, such as scroll bars, supports the contention that these are fluvially formed fans. Martian fans, at least those in Holden crater, apparently formed around the time of the Noachian-Hesperian boundary. We infer that these fans formed during an episode of enhanced precipitation (probably snow) and runoff, which exhibited both sudden onset and termination.

  18. Sedimentary facies, depositional environments and palaeogeographic evolution of the Neogene Denizli Basin, SW Anatolia, Turkey

    NASA Astrophysics Data System (ADS)

    Alçiçek, Hülya; Varol, Baki; Özkul, Mehmet

    2007-12-01

    The Denizli Basin (southwestern Anatolia, Turkey) contains a record of environmental changes dating since the Early Miocene. Detailed facies analysis of the Neogene formations in this half-graben enables us to document successive depositional regimes and palaeogeographic settings. Sedimentation commenced in the Early Miocene with the deposition of alluvial-fan and fluvial facies (K?z?lburun Formation). At this stage, alluvial fans sourced from elevated areas to the south prograded towards the basin centre. The Middle Miocene time saw the establishment of marginal lacustrine and wetland environments followed by the development of a shallow lake (Sazak Formation). The uppermost part of this unit consists of evaporitic saline lake and saline mudflat facies that grade upward into brackish lacustrine deposits of Late Miocene-Pliocene age (Kolankaya Formation). The lake became shallower at the end of the Pliocene time, as is indicated by expansion shoreface/foreshore facies. In the Early Quaternary, the Denizli Basin was transformed into a graben by the activation of ESE-trending normal faults. Alluvial fans were active at the basin margins, whereas a meandering river system occupied the basin central part. Oxygen isotope data from carbonates in the successive formations show an alternation of wetter climatic periods, when fresh water settings predominated, and very arid periods, when the basin hosted brackish to hypersaline lakes. The Neogene sedimentation was controlled by an active, ESE-trending major normal fault along the basin's southern margin and by climatically induced lake-level changes. The deposition was more or less continuous from the Early Miocene to Late Pliocene time, with local unconformities developed only in the uppermost part of the basin-fill succession. The unconformable base of the overlying Quaternary deposits reflects the basin's transformation from a half-graben into a graben system.

  19. The timing of alluvial activity in Gale crater, Mars

    NASA Astrophysics Data System (ADS)

    Grant, John A.; Wilson, Sharon A.; Mangold, Nicolas; Calef, Fred; Grotzinger, John P.

    2014-02-01

    The Curiosity rover's discovery of rocks preserving evidence of past habitable conditions in Gale crater highlights the importance of constraining the timing of responsible depositional settings to understand the astrobiological implications for Mars. Crater statistics and mapping reveal the bulk of the alluvial deposits in Gale, including those interrogated by Curiosity, were likely emplaced during the Hesperian, thereby implying that habitable conditions persisted after the Noachian. Crater counting data sets and upper Peace Vallis fan morphology also suggest a possible younger period of fluvial activation that deposited ~10-20 m of sediments on the upper fan after emplacement of the main body of the fan. If validated, water associated with later alluvial activity may have contributed to secondary diagenetic features in Yellowknife Bay.

  20. Stable isotope variations in the Quaternary epithermal calcite-fluorite deposit at Monte delle Fate near Cerveteri (Latium, central Italy)

    USGS Publications Warehouse

    Masi, U.; O'Neil, J.R.

    1980-01-01

    Carbon, oxygen and hydrogen isotope variations have been measured in samples from the epithermal fluorite vein deposit at Monte delle Fate, Latium. The ranges in ?? 13C and ??18O of calcite are -1.3 to 3.4 and 9.5 to 17.3, respectively. ??D values of water extracted from fluid inclusions are -49 to -39 for calcite and -41 to -34 for fluorite. Fluid inclusion filling temperatures (225??-240??C) and salinites (3.75) are nearly the same for both fluorite and sparry calcite. An elongated form of calcite, of minor abundance, precipitated at lower temperatures. The data indicate that (1) the CO2 involved in the mineralization was provided by the local marine limestones, (2) the waters were meteoric in origin and underwent an 18O shift of ??? 10 permil by exchange with marine country rocks, and (3) all geochemical features can be explained by the action of two hydrothermal fluids. Hot brines recently discovered in the Cesano geothermal area, 30 km to the east, have temperatures and some chemical characteristics similar to the hydrothermal fluids at Monte delle Fate. ?? 1980 Springer-Verlag.

  1. The use of O, H and Sr isotopes and carbamazepine to identify the origin of water bodies supplying a shallow alluvial aquifer

    NASA Astrophysics Data System (ADS)

    Sassine, Lara; Le Gal La Salle, Corinne; Lancelot, Joël; Verdoux, Patrick

    2014-05-01

    Alluvial aquifers are of great socio-economic importance in France since they supply 82% of drinking water production, though they reveal to be very vulnerable to pesticides and emerging organic contaminants. The aim of this work is to identify the origin of water bodies which contribute to the recharge of an alluvial aquifer for a better understanding of its hydrochemistry and transfer of contaminants therein. The study is based on an isotopic and geochemical tracers approach, including major elements, trace elements (Br, Sr),and isotopes (?18O, ?2H, 87Sr/86Sr), as well as organic molecules. Indeed, organic molecules such as pharmaceutical compounds, more precisely carbamazepine and caffeine, have shown their use as indicators of surface water in groundwater. The study area is a partially-confined shallow alluvial aquifer, the so-called Vistrenque aquifer, located at 15 km from the Mediterranean Sea, in the Quaternary alluviums deposited by an ancient arm of the Rhône River, in Southern France. This aquifer constitutes a shallow alluvial layer in a NE-SW graben structure. It is situated between a karst aquifer in lower Cretaceous limestones, on the NW border, and the Costières Plateau, on the SE border, having a similar geology as the Vistrenque. The alluvial plain is crossed by a surface water network with the Vistre as the main stream, and a canal used for irrigation essentially, the BRL canal, which is fed by the Rhône River. ?18O and ?2H allowed to differentiate the BRL canal water, depleted in heavy isotopes (?2H = -71.5o vs V-SMOW), and the more enriched local rainwater (?2H = -35.5o vs V-SMOW). In the Vistre surface water a binary mixing were evidenced with the BRL canal water and the rainwater, as end members. Then, in the Vistrenque groundwater both the BRL and the Vistre contributions could be identified, as they still show contrasting signature with local recharge. This allows to highlight the surface water contribution to a heavily exploited alluvial aquifer. These mixing processes are confirmed by comparing O and H isotopes to major elements composition. Furthermore, organic compound concentrations such as carbamazepine which show relatively high concentrations in surface waters, was also detected in groundwater especially in those influenced by the BRL canal water, and hence may be used as a tracer of surface water contribution. On the other hand, 87Sr/86Sr allowed highlighting this time a mixing process between groundwater bodies contributing to the recharge of the alluvial aquifer. The 87Sr/86Sr vs 1/Sr plot showed a locale influence on the Vistrenque groundwater by the karst limestone aquifer (87Sr/86Sr ?0.7076; [Sr] =1540 ?g/L), and the Costières Plateau water (87Sr/86Sr ?0.7090; [Sr] =320 ?g/L). In conclusion, 18O and 2H isotopes allowed to highlight the influence of surface waters on the quality of a shallow vulnerable alluvial aquifer, by determining the relationship between the two water bodies. While 87Sr/86Sr were useful to identify mixing processes between groundwater bodies from aquifers of different geology, the limestone karst and alluvial sediments. A multi-isotope approach proved useful to understand the origin of water bodies and contaminants.

  2. Autogenic attainment of large-scale alluvial grade with steady sea-level fall: An analog tank-flume experiment

    Microsoft Academic Search

    Tetsuji Muto; John B. Swenson

    2006-01-01

    A graded river conveys its sediment load without net deposition or erosion. The graded state is thought to represent the long-term response of alluvial rivers to steady external forcing. We show here that alluvial rivers building deltas can be in grade as an autogenic response to steady sea-level fall. Consider an antecedent graded river profile, the upstream end of which

  3. Quaternary Tectonic and Climatic Processes shaping the Central Andean hyperarid forearc (southern Peru)

    NASA Astrophysics Data System (ADS)

    Audin, Laurence; Benavente, Carlos; Zerathe, Swann; Saillard, Marianne; Hall, Sarah R.; Farber, Daniel L.

    2015-04-01

    Understanding the forearc structure and processes related to Quaternary evolution and uplift of the Western Andean Cordillera remains an outstanding scientific issue. Models of Andean Plateau evolution based on Tertiary volcanic stratigraphy since 5Ma suggest that the deformation was focused along the eastern margin of the plateau and that minimal uplift occurred along the Pacific margin. On the contrary, new tectonic data and Quaternary surface 10Be dating highlight the presence of recently active deformation, incision and alluvial processes within the upper Andean forearc together with a regional uplift of the coastal zone. Additionally, the high obliquity observed in the northern Arica Bend region makes it an ideal target to discuss whether partitioning of the oblique convergence is accommodated by the neotectonic features that dissect the Quaternary forearc. Our goals are both to decipher the Quaternary tectonic and climatic processes shaping the hyperarid forearc along strike and across strike. Finally, we aim to quantify the respective influence of these factors in the overall uplift of the Western Andes. Indeed, sequences of pediment surfaces, landslide products, paleolake deposits and marine terraces found along the oblique Peruvian margin are a unique set of datable markers that can be used to quantify the rates of Quaternary processes. In this study, we focus on the southern Peru hyperarid Atacama area where regional surfaces and tectonic markers (scarps, folds, temporary streams and paleolake levels offsets…) are well preserved for the Quaternary timescale. Numerous landsliding events align on the major fault segments and reflect Plio-Pleistocene climatic and tectonic activity together with filled and strath terraces. As the present day sea-level is one of the highest levels recorded for Quaternary time span, any emerged marine terrace is preserved by tectonic coastal uplift. In particular, the geomorphic and chronologic correlation between marine and continental planation surfaces or terraces permit to deduce net vertical rates and suggests that the along strike uplift affected not only the coast but also the overall ~50 km-wide forearc of the Western Andes. We produced a chronology of remnant low-relief surfaces and a new neotectonic map of the Central Andean forearc between ~14° and 18°S based on detailed field mapping and 10Be cosmogenic dating. We address 1) the spatial and temporal correlations of various markers, and 2) the correlation of the surface abandonment ages to various regional climatic events and 3) the description of neotectonic activity accommodating both uplift and partitioning. Multiple markers yield 10Be surface abandonment ages that spanning 35 ka to >2 Ma. Erosion surfaces >2 Ma yield low erosion rates of <0.1mm/yr. However uplift rates of ~0.1-1mm/yr and multiple surfaces dated at ~35 ka suggest that the hyperarid forearc landscape has been recently modified through Quaternary surface uplift and climatic events, contradicting the Miocene fossil forearc hypothesis. Generally, surface abandonment ages and activated landslides periods tend to correlate with cold wet periods preceding Plio Pleistocene deglaciation on the Altiplano. Finally, neotectonic oblique faults connecting at depth participate to topography building in the Arica Bend region and suggest that Quaternary surface abandonment is the result of both surface uplift in the forearc and specific high-discharge climate periods in the high Andes. Obtained Quaternary regional uplift rates and individual slip-rates suggest that the Andean forearc may accommodate as much as 0.5 to 1 mm/yr of regional uplift for the Quaternary time period.

  4. Investigation of Quaternary slip rates along the Banning strand of the southern San Andreas Fault near San Gorgonio Pass

    NASA Astrophysics Data System (ADS)

    Gold, P. O.; Behr, W. M.; Rood, D.; Kendrick, K. J.; Rockwell, T. K.; Sharp, W. D.

    2013-12-01

    Present-day Pacific-North American relative plate motion in southern California is shared primarily between the San Jacinto and San Andreas faults. At the north end of the Coachella Valley, the San Andreas fault splits into the Banning and Mission Creek strands, which are sub-parallel to each other within the Indio Hills. Northwest of the Indio Hills, the Mission Creek fault diverges from the Banning and continues northwest toward the southeastern San Bernardino Mountains, but loses surface expression beneath Quaternary alluvial deposits in Morongo Wash. The Banning fault, upon exiting the Indio Hills, is deflected toward the west and transitions into a structurally complex fault zone at San Gorgonio Pass, where it is delineated by thrust scarps in Holocene alluvium. The slip rates of the Banning and Mission Creek fault strands northwest of the Indio Hills and southeast of San Gorgonio Pass are presently unconstrained, but understanding how slip is partitioned between these two strands is critical to southern California earthquake forecasting efforts. Here we present preliminary slip rate data for the Banning fault ~2 km southeast of San Gorgonio Pass at Devers Hill. Using the B4 LiDAR as a base, we have mapped the extents of three truncated and offset alluvial fan deposits, which we have differentiated based on both field and remote (LiDAR- and air photo-based) observations of texture: in particular, the distribution of different clast sizes, pavement and soil development, and color and appearance. To confirm across-fault correlation of the displaced deposits, we have measured 26 cosmogenic Be-10 ages from boulders and cobble samples taken from each of the three fan surfaces on both sides of the fault. One debris flow deposit (Q2a) has been dated to ~80 ka, and appears to be offset 1.6-2.2 km, though confirming this reconstruction will depend on future excavations and uranium-series dating of soil carbonate. A second debris flow deposit (Q2b), for which ages are pending, has been displaced 1-1.6 km. Together, these measurements suggest a late Quaternary slip rate for the Banning strand of the San Andreas fault of about 12-24 mm/yr. Our preliminary slip rate measurement for the Banning strand just southeast of San Gorgonio Pass is consistent with the slip rate of the San Bernardino section of the San Andreas fault to the northwest, and suggests that averaged over late Quaternary timescales (~80 ka), displacement along the San Andreas south of San Gorgonio Pass may be more focused on the Banning strand than the Mission Creek strand.

  5. Irish Quaternary Association (IQUA)

    NSDL National Science Digital Library

    The Irish Quaternary Association (IQUA) website publicizes its aim "to promote Quaternary studies in Ireland through its publications, and the organization of field meetings and conferences." Visitors can learn about the importance of quaternary studies, find out the latest news and upcoming meetings, and find links to Quaternary studies journals.

  6. Quaternary Geochronology, Paleontology, and Archaeology of the Upper San Pedro River Valley, Sonora, Mexico

    NASA Astrophysics Data System (ADS)

    Gaines, E. P.

    2013-12-01

    This poster presents the results of multi-disciplinary investigations of the preservation and extent of Quaternary fossil-bearing strata in the San Pedro River Valley in Sonora, Mexico. Geologic deposits in the portions of the San Pedro Valley in southern Arizona contain one of the best late Cenozoic fossil records known in North America and the best record of early humans and extinct mammals on the continent. The basin in the U.S. is one of the type locations for the Blancan Land Mammal Age. Hemiphilian and Irvingtonian fossils are common. Rancholabrean remains are widespread. Strata in the valley adjacent to the international border with Mexico have yielded the densest concentration of archaeological mammoth-kill sites known in the western hemisphere. Despite more than 60 years of research in the U.S., however, and the fact that over one third of the San Pedro River lies south of the international boundary, little has been known about the late Cenozoic geology of the valley in Mexico. The study reported here utilized extensive field survey, archaeological documentation, paleontological excavations, stratigraphic mapping and alluvial geochronology to determine the nature and extent of Quaternary fossil-bearing deposits in the portions of the San Pedro Valley in Sonora, Mexico. The results demonstrate that the Plio-Pleistocene fossil -bearing formations known from the valley in Arizona extend into the uppermost reaches of the valley in Mexico. Several new fossil sites were discovered that yielded the remains of Camelids, Equus, Mammuthus, and other Proboscidean species. Late Pleistocene archaeological remains were found on the surface of the surrounding uplands. AMS radiocarbon dating demonstrates the widespread preservation of middle- to late- Holocene deposits. However, the late Pleistocene deposits that contain the archaeological mammoth-kill sites in Arizona are absent in the valley in Mexico, and are now known to be restricted to relatively small portions of the valley immediately north of the international border.

  7. Variation in sedimentology and architecture of Eocene alluvial strata, Wind River and Washakie basins, Wyoming

    SciTech Connect

    Patterson, P.E.; Larson, E.E. (Univ. of Colorado, Boulder (United States))

    1991-03-01

    Eocene continental, alluvial strata of the Wind River Formation (Wind River Basin) and the Cathedral Bluffs Member of the Wasatch Formation (Washakie basin) provide two examples of Laramide intermontane basin aggradation. These alluvial sediments primarily represent overbank flood deposits marginal to channel complexes. Their sedimentology and architecture, although grossly similar, appear to vary somewhat with proximity to Laramide uplifts. In both cases, repetitive sedimentation on the floodplain produced a succession of depositional couplets, each composed of a light-gray sand overlain by a red clay-rich silt or sand. The lower sands are tabular bodies that, near their distal margins, taper discernibly. They commonly display planar and ripple-drift laminations. Upper clay-rich layers, which are laminated, are also generally tabular. Those floodplain strata depositional proximal to Laramide uplifts show little evidence of scouring prior to deposition of the next, overlying couplet. Most of these sedimentary layers, therefore, are laterally continuous (up to 2 km). This alluvial architecture results in relatively uniform porosity laterally within depositional units but variable porosity stratigraphically through the sequence. In contrast, alluvial sediments deposited farther from the Laramide uplifts have undergone sporadic incision (either during rising flood stage or subsequently) followed by aggradation. As a result, many of these floodplain couplets are discontinuous laterally and, hence, exhibit large-scale lateral variability in porosity. Both alluvial sequences have undergone similar types and extents of burial diagenesis.

  8. Paleovalley systems: Insights from Quaternary analogs and experiments

    NASA Astrophysics Data System (ADS)

    Blum, M.; Martin, J.; Milliken, K.; Garvin, M.

    2013-01-01

    Ancient fluvial valley systems are long recognized as important features in the stratigraphic record, but emerged as a specific focus of attention with publication of first-generation sequence-stratigraphic concepts. This paper reviews current understanding of paleovalley systems from the perspective of Quaternary analogs and experimental studies. Paleovalley systems can include distinct mixed bedrock-alluvial, coastal-plain, and cross-shelf segments. Mixed bedrock-alluvial segments are long-lived, cut across bedrock of significantly older age, and have an overall degradational architecture. By contrast, coastal-plain and cross-shelf segments are non-equilibrium responses to high-frequency cycles of relative sea-level change: most coastal-plain and cross-shelf segments form as a geometric response to relative sea-level fall, as river systems cut through coastal-plain and inner shelf clinothems, and extend basinward to track the shoreline. After incision and cross-shelf extension, lateral channel migration and contemporaneous channel-belt deposition creates a valley-scale feature. Coastal-plain and cross-shelf paleovalley widths are set by the number of channel-belt sandbodies deposited during this time. Paleovalley systems play a key role in source-to-sink sediment routing. Early views included the model of incision and complete sediment bypass in response to relative sea-level fall. However, this model does not stand up to empirical, theoretical, or experimental scrutiny. Instead, there is a complex dynamic between incision, deposition, and sediment export from an evolving valley: periods of incision correspond with sediment export minima, whereas periods of lateral migration and channel-belt construction result in increased flux to the river mouth. Sediment export from evolving valleys, and merging of drainages during cross-shelf transit, play key roles in sediment transfer to the shelf-margin and genetically-linked slope to basin-floor systems. Connection between the river mouth and the shelf margin likely occurs for different periods of time depending on gradient of the river and shelf, as well as amplitude of high-frequency sea-level changes. Late Quaternary analogs and experimental studies provide an alternative sequence-stratigraphic interpretation for paleovalley systems. In coastal-plain paleovalleys, basal valley-fill surfaces meet criteria for an unconformity and a classically-defined sequence boundary: however, this surface is mostly everywhere of the same age as overlying fluvial deposits, and does not correspond to a long period of incision and sediment bypass. In cross-shelf paleovalleys, the basal contact between fluvial and deltaic or shoreface deposits is commonly interpreted as a sequence boundary, but is not an unconformity characterized by incision and sediment bypass. Instead, this surface is a facies contact that separates genetically-related fluvial and deltaic strata: the surface that correlates to the basal valley-fill surface within the coastal-plain paleovalley dips below cross-shelf prograding deltaic and/or shoreface strata, which are fed by deposition within the evolving valley itself, and should be the downlap surface. Many issues deserve attention in the future. We have stressed understanding the inherent scales and physical processes that operate during the formation and evolution of paleovalley systems. We also suggest the relative roles of allogenic forcing vs. autogenic dynamics, and the potential significance of high-frequency isostatic adjustments should be topics for future discussion.

  9. Integration of channel and floodplain suites. I. Developmental sequence and lateral relations of alluvial paleosols.

    USGS Publications Warehouse

    Bown, T.M.; Kraus, M.J.

    1987-01-01

    The lower Eocene Willwood Formation of the Bighorn Basin, northwest Wyoming, consists of about 770 m of alluvial rocks that exhibit extensive mechanical and geochemical modifications resulting from Eocene pedogenesis. Five arbitrary stages are proposed to distinguish these soils of different maturities in the Willwood Formation. An inverse relationship exists between soil maturity and short-term sediment accumulation rate. Illustrates several important principles of soil-sediment interrelationships in aggrading alluvial systems that have broad application to other deposits.-from Authors

  10. Active erosion-deposition cycles in the hyperarid Atacama Desert of Northern Chile

    NASA Astrophysics Data System (ADS)

    Jungers, Matthew C.; Heimsath, Arjun M.; Amundson, Ronald; Balco, Greg; Shuster, David; Chong, Guillermo

    2013-06-01

    There is significant debate over the rates and types of fluvial activity at the Plio-Pleistocene boundary in the hyperarid Atacama Desert of Chile. To quantify fluvial processes and help resolve this debate, we measure terrestrial cosmogenic nuclide (TCN) (10Be and 21Ne) concentration depth profiles in three settings representing a chronosequence: (1) a late Pliocene alluvial fan representative of major regional deposits, (2) a modern, active channel and (3) an adjacent low terrace inset into the Pliocene alluvium. Late Pliocene deposits that are widely preserved in the region contain TCN profiles consistent with relatively rapid stripping of upland sediment at the Plio-Pleistocene boundary. Deposits inset into these Late Pliocene features record cut and fill cycles that rework sediment throughout the Quaternary. The TCN profile in the modern channel is best explained by sediment aggradation at 2.1 m Myr-1 during the last 250,000 yr. Similarly, the adjacent low terrace sediments contain TCN concentration profiles consistent with aggradation of 2.0 m Myr-1 over a period of 250,000-750,000 yr prior to the last 250,000 yr of stability. In summary, depth profiles of two TCNs provide constraints on the rates of sediment deposition, sources of sediment and transport history, as well as the subsequent exposure conditions of the sediment following deposition. Our results are consistent with early Quaternary initiation of hyperaridity for the region. During the Quaternary, winter precipitation events experienced at our sites' latitude (24°S) drive active erosion-deposition cycles. The northward migration of the subtropical front during Quaternary glacial cycles may have enhanced precipitation at 24°S, leading to more active fluvial processes during cooler periods.

  11. Lateral groundwater inflows into alluvial aquifers of main alpine valleys

    NASA Astrophysics Data System (ADS)

    Burger, Ulrich

    2015-04-01

    In alpine regions the topography is mainly characterised by deep incised valleys, mountain slopes and ridges. Usually the main valleys contain aquifers in alluvial soft rock. Lateral these aquifers are confined by mountainous hard rock slopes covered by heterogeneous sediments with different thickness. The slopes can be incised by lateral valleys. Numerical models for the main alluvial aquifers ask for lateral hydrogeological boundaries. Usually no flow boundaries or Constant head Boundaries are used, even if the lateral inflows to the main aquifers are rarely known. In this example a data set for a detailed investigated and monitored area is studied to give an answer on the location and the quantification of these lateral subsurface inflows. The study area is a typical main alpine valley with a thick alluvial aquifer (appr. 120m thick), lateral confined by granite, covered at the base of the steep slopes by quaternary sediments (Burger at al. 2012). The study consists of several steps 1.) Analytical calculation of the inflows on the base of investigated and monitored 2d profiles along fault zones (Perello et al 2013) which pinch out in the main valley 2.) Analytical models along typical W-dipping slopes with monitored slope springs 3.) Evaluating temperature and electrical conductivity profiles measured in approx. 30 groundwater wells in the alluvial aquifers and along the slopes to locate main lateral subsurface inflows 4.) Output of a regional model used for the hydrogeological back analyses of the excavation of a tunnel (Baietto et al. 2014) 5.) Output of a local numerical model calibrated with a monitoring dataset and results of a pumping test of big scale (450l/s for 10days) Results of these analyses are shown to locate and quantify the lateral groundwater inflows in the main alluvial aquifer. References Baietto A., Burger U., Perello P. (2014): Hydrogeological modelling applications in tunnel excavations: examples from tunnel excavations in granitic rocks; congress of IAEG, Engineering Geology for Society and Territory, Torino Burger U., San Nicoló L. Bösel D. und Perello P. (2012): Hydrogeologische Modelle - Hilfsmittel für die Planung am Beispiel des Brenner Basistunnel, Beiträge zur Beiträge zur COGeo 2011, Salzburg COGEO Perello P., Baietto A., Burger U., Skuk S. (2013): Excavation of the Aica-Mules pilot tunnel for the Brenner base tunnel: information gained on water inflows in tunnels in granitic massifs, Rock Mechanics and Rock Engineering, DOI 10.1007/s00603-013-0480-x

  12. Climatic and tectonic controls on Quaternary eolian sedimentary sequences of the Chott Rharsa Basin, southern Tunisia

    Microsoft Academic Search

    Christopher Stephen Swezey

    1997-01-01

    This dissertation presents an investigation of climatic and tectonic controls on Quaternary eolian sedimentary sequences of the Chott Rharsa Basin on the northern margin of the Sahara Desert, in southern Tunisia. This basin, which lies within the larger Atlas foreland basin of North Africa, is a structurally controlled depocenter created by Miocene-Pleistocene compression associated with the Atlas Orogeny. Alluvial fans

  13. A comparison and integration of tree-ring and alluvial records of fire history at the Missionary Ridge Fire, Durango, Colorado, USA

    Microsoft Academic Search

    Erica Bigio; Thomas W. Swetnam; Christopher H. Baisan

    2010-01-01

    We used tree-ring and alluvial sediment methods to reconstruct past fire regimes for a mixed conifer forest within a 1 km2 drainage basin which was severely burned by a wildfire near Durango, Colorado. Post-fire debris flow events incised the valley-filling alluvial sediments in the lower basin, and created exposures of fire-related of deposits of late-Holocene age. Tree-ring and alluvial sediment

  14. Types of sedimentary environment in alluvial sediments distinguished on the basis of its chemical constitution: the example of the lower course of the Obra river (Western Poland)

    Microsoft Academic Search

    Marcin S?owik; Tadeusz Sobczy?ski; Zygmunt M?ynarczyk

    2010-01-01

    Research concerning chemical constitution of alluvial sediments was done in the lower course of the Obra river (Western Poland).\\u000a The fragment of vertical profile, which consisted of various alluvial sediments (fine sands, peats, and sandy silts) was chosen\\u000a for detailed analysis. The main research problem was to determine if lithology and chemical constitution of alluvial deposits\\u000a are interconnected in a

  15. A model of late quaternary landscape development in the Delaware Valley, New Jersey and Pennsylvania

    USGS Publications Warehouse

    Ridge, J.C.; Evenson, E.B.; Sevon, W.D.

    1992-01-01

    In the Delaware Valley of New Jersey and eastern Pennsylvania the late Quaternary history of colluviation, fluvial adjustment, and soil formation is based on the ages of pre-Wisconsinan soils and glacial deposits which are indicated by feld relationships and inferred from mid-latitude climate changes indicated by marine oxygen-isotope records. The area is divided into four terranes characterized by sandstone, gneiss, slate and carbonate rocks. Since the last pre-Wisconsinan glaciation (> 130 ka, inferred to be late Illinoian), each terrane responded differently to chemical and mechanical weathering. During the Sangamon interglacial stage (??? 130-75 ka) in situ weathering is inferred to have occurred at rates greater than transportation of material which resulted in the formation of deep, highly weathered soil and saprolite, and dissolution of carbonate rocks. Cold climatic conditions during the Wisconsinan, on the other hand, induced erosion of the landscape at rates faster than soil development. Upland erosion during the Wisconsinan removed pre-Wisconsinan soil and glacial sediment and bedrock to produce muddy to blocky colluvium, gre??zes lite??es, and alluvial fans on footslopes. Fluvial gravel and overlying colluvium in the Delaware Valley, both buried by late Wisconsinan outwash, are inferred to represent episodes of early and middle Wisconsinan (??? 75-25 ka) upland erosion and river aggradiation followed by river degradation and colluvium deposition. Early-middle Wisconsinan colluvium is more voluminous than later colluvium despite colder, possibly permafrost conditions during the late Wisconsinan ??? 25-10 ka). Extensive colluviation during the early and middle Wisconsinan resulted from a longer (50 kyr), generally cold interval of erosion with a greater availability of easily eroded pre-Wisconsinan surficial materials on uplands than during the late Wisconsinan. After recession of late Wisconsinan ice from its terminal position, soil formation and landscape stability were delayed until the Holocene by a lingering cold climate, slope erosion, colluvium and alluvial fan deposition, and eolian sedimentation. Late Quaternary erosion in the Delaware Valley was dominated by glacial and periglacial processes during glacial stages. During the warm interglacial stages, soils developed on a more stable landscape. These souls were easily colluviated by periglacial erosion during periods of intermittent cold climate. ?? 1992.

  16. Uplift of quaternary shorelines in eastern Patagonia: Darwin revisited

    Microsoft Academic Search

    Kevin Pedoja; Vincent Regard; Laurent Husson; Joseph Martinod; Benjamin Guillaume; Enrique Fucks; Maximiliano Iglesias; Pierre Weill

    2011-01-01

    During his journey on the Beagle, Darwin observed the uniformity in the elevation of coastal Eastern Patagonia along more than 2000km. More than one century later, the sequences of Quaternary shorelines of eastern Patagonia have been described and their deposits dated but not yet interpreted in terms of geodynamics. Consequently, we i) mapped the repartition of the Quaternary coastal sequences

  17. Distinguishing early groundwater alteration effects from pedogenesis in ancient alluvial basins: examples from the Palaeogene of southern Portugal

    NASA Astrophysics Data System (ADS)

    Pimentel, N. L.; Wright, V. P.; Azevedo, T. M.

    1996-08-01

    Colour mottling and horizons of secondary carbonates are common in ancient alluvial sequences and are normally interpreted as pedogenic features. They have been used to assess palaeoclimates, soil drainage conditions and deposition rates. Palaeogene alluvial deposits in the Sado and Lisbon basins of Portugal exhibit prominent colour variations and mottle patterns, as well as carbonate accumulations both at the bases of fining-upwards cyclothems and as thick units (up to 20 m) capping alluvial megasequences. However, these colour and carbonate features are interpreted as the products of shallow, saline, reducing groundwaters, unrelated to pedogenesis. Such non-pedogenic products are easily mistaken for soil-formed ones and criteria for differentiating the two are reviewed to assist interpretations in other alluvial deposits. Key criteria are thickness, gradational tops and bases, absence of soil horizon features, occurrence in coarser alluvium and prevalence of hydromorphic colour and mottling patterns.

  18. Early Cretaceous stratigraphy, paleontology, and sedimentary tectonics in Paris overthrust foredeep (western Wyoming and southeastern Idaho) compared with Quaternary features of indo-gangetic plain

    SciTech Connect

    Dorr, J.A. Jr.

    1983-08-01

    Fluviatile clastics of the nonmarine, early Cretaceous Gannett and Wayan groups were deposited on wet alluvial megafans and on intervening interfan piedmont slopes which declined eastward into more poorly drained lowlands from a western highland source area uplifted episodically by movements of the Paris overthrust. Lacustrine episodes of deposition intercalated Peterson and Draney limestones with Gannett fluvial clastics. Westward marine transgressions (Skull Creek, Mowry) intercalated mixed lacustrine and brackish facies (Smiths and Cokedale formations) into Wayan fluviatile clastics. Newly discovered fossil vertebrate and invertebrate materials (all fragmentary but identifiable) include: Gannett Group - large reptiles including turtles; Thomas Fork Formation - freshwater gastropods and unionid pelecypods, gastroliths, two types of turtles, large reptilian fragments (dinosaur), and abundant dinosaur eggshell fragments; Wayan Formation - perennially aquatic snails, turtles, unidentifiable large reptiles, two types of crocodilians, an iguanodontid dinosaur (Tenontosaurus), an ankylosaurian dinosaur, a large ornithopod dinosaur, gastroliths, abundant and ubiquitous dinosaur eggshell fragments (numerous types and sizes), and miscellaneous unidentifiable small vertebrate bone fragments. A census of analogous modern reptile reproductive behaviors supports the conclusion that the Wayan, and probably also the Gannett, alluvial fan environments were used as upland breeding grounds by dinosaurs and perhaps other reptiles. Comparison of these Early Cretaceous data with observations on the tectonic setting, sedimentology, and biology of the Quaternary indo-gangetic plain suggests many close analogies between the two sedimentary tectonic settings.

  19. Quaternary and Geomorphology.

    ERIC Educational Resources Information Center

    Andrews, J. T.; Graf, W. L.

    1983-01-01

    Highlights conferences and meetings of organizations involved with quaternary geology and geomorphology, including International Union of Quaternary Research Conference held in Moscow. The impetus of a revision of "The Quaternary of the United States" resulted from this conference. Includes activities/aims of "Friends of the Pleistocene"…

  20. Geochemistry of carbonate cements in surficial alluvial conglomerates and their paleoclimatic implications, Sultanate of Oman

    SciTech Connect

    Burns, S.J.; Matter, A. [Univ. Bern (Switzerland). Geologisches Inst.

    1995-01-02

    Early diagenetic carbonate cements are a common feature of Quaternary alluvial conglomerates in Oman. Cements are formed in the vadose and, more commonly, phreatic zones from near-surface groundwaters. In drainage areas underlain by the Semail Ophiolite, groundwaters have Mg{sup 2+}/Ca{sup 2+} ratios greater than two, and cements are often dolomite or high-magnesium calcite in addition to low-magnesium calcite. In drainage areas underlain by limestone, groundwaters have Mg{sup 2+}/Ca{sup 2+} ratios of around one or less and cement mineralogy is nearly always low-magnesium calcite. The oxygen and carbon stable isotopic ratios of the cements vary widely, from {minus}10.6{per_thousand} to +3.0{per_thousand} PDB and from {minus}10.0{per_thousand} to +0.7{per_thousand} PDB, respectively. Cement {delta}{sup 18}O values principally reflect variation in rainfall {delta}{sup 18}O over a time scale of several thousand years. Rainfall and cement {delta}{sup 18}O values probably are inversely correlated with the amount of rainfall, which is related to the frequency and intensity of the Indian Ocean monsoon. Thus, cement {delta}{sup 18}O is potentially a proxy indicator of relative rainfall and monsoon activity. For each of three sampling areas, {delta}{sup 13}C is positively correlated to {delta}{sup 18}O. Cement {delta}{sup 13}C values are also related to rainfall amount because rainfall controls the plant population. Greater plant respiration of isotopically depleted CO{sub 2} to shallow groundwaters and burial of organic material in conglomerate deposits results in lower cement {delta}{sup 13}C values compared to periods of lesser plant activity.

  1. Quaternary geology and geomorphology of the Sacramento-San Joaquin Delta, California: evolution and processes

    NASA Astrophysics Data System (ADS)

    Gatti, E.; Maier, K. L.; Holzer, T. L.; Knudsen, K. L.; Olson, H.; Pagenknopp, M.; Ponti, D. J.; Rosa, C.; Tinsley, J. C.; Wan, E.

    2013-12-01

    The Sacramento-San Joaquin Delta (~1,400 km2) is a combination of tidal marsh, islands and agricultural lands at the confluence of the Sacramento and the San Joaquin Rivers, in northern California. Most of the Delta islands are now 3 to 8 m below sea-level and must be protected by levees from inundation. Because of the Delta's crucial role in conveying fresh water to the State, levee failures can cause substantial economic loss by disrupting this supply. Understanding the evolution of the Delta is fundamental to assess the vulnerability of the Delta islands to seismically-induced levee failure. The modern Delta is a young geological feature that began forming during the middle Holocene. Preceding versions of the Delta hosted a variety of depositional environments as sea level fluctuated, responding to climatically-controlled changes. The rising sea reached the Delta about 8,000 years ago, and modern deltaic evolution continued into Holocene time until present. More accurate stratigraphic studies incorporating depositional ages are required to i) better understand the late Quaternary evolution of the Delta, ii) trace the base of Holocene deposits, iii) identify potentially active faults, and iv) evaluate liquefaction hazard for the Delta . This study uses the large amount of data available on the Delta (collected by the California Department of Water Resources and others during the past 30 years) and merges them into a unified dataset. We have produced a database that includes historic and surficial maps, aerial photographs, boreholes, and CPT data, for the purpose of clarifying the nature of the Quaternary deposits and the evolution of the Late Quaternary Delta. Additionally, we have identified recently discovered Pleistocene tephra as the Rockland ash, ~0.575 Ma, and the Loleta ash, ~0.40-0.37 Ma, which have improved stratigraphic correlations and assessment of subsidence rates. Delta sediments include sequences of glacial and interglacial deposits. Borehole logs reveal sequences of incision and backfilling corresponding to major climatic fluctuations: incised channels, sand-filling channels, gravel alluvial fans and eolian dunes during glacial periods, and fine-grained alluvial floodplains, mud flats deposits, marshes and peat during warmer interglacials. The evolution of the Delta is likely the result of three processes: subsidence (based on tephra ages, between ~0.004 cm/yr and 0.007 cm/yr in the Northern Delta, ~0.01 cm/yr in the central Delta, ~0.06 cm/yr in the Eastern Delta), compaction due to organic soil oxidation (3.6-6.1 cm/yr), and tectonic control. The thickness of the organic soils (>20 m) suggests that the Holocene sea-level rise was the major factor controlling the Delta's morphology before agricultural drainage began in the 1850's. Because the patterns suggest that sea-level rise was the major cause of changes in the Delta, it is likely that once the organic soil is all oxidized by anthropogenic processes within a few centuries, the major controlling factor will become anthropogenic sea-level rise.

  2. Bedload transport in alluvial channels

    USGS Publications Warehouse

    Bravo-Espinosa, M.; Osterkamp, W.R.; Lopes, V.L.

    2003-01-01

    Hydraulic, sediment, land-use, and rock-erosivity data of 22 alluvial streams were used to evaluate conditions of bedload transport and the performance of selected bedload-transport equations. Transport categories of transport-limited (TL), partially transport-limited (PTL), and supply-limited (SL) were identified by a semiquantitative approach that considers hydraulic constraints on sediment movement and the processes that control sediment availability at the basin scale. Equations by Parker et al. in 1982, Schoklitsch in 1962, and Meyer-Peter and Muller in 1948 adequately predicted sediment transport in channels with TL condition, whereas the equations of Bagnold in 1980, and Schoklitsch, in 1962, performed well for PTL and SL conditions. Overall, the equation of Schoklitsch predicted well the measured bedload data for eight of 22 streams, and the Bagnold equation predicted the measured data in seven streams.

  3. Geomorphic Processes and Remote Sensing Signatures of Alluvial Fans in the Kun Lun Mountains, China

    NASA Technical Reports Server (NTRS)

    Farr, Tom G.; Chadwick, Oliver A.

    1996-01-01

    The timing of alluvial deposition in arid and semiarid areas is tied to land-surface instability caused by regional climate changes. The distribution pattern of dated deposits provides maps of regional land-surface response to past climate change. Sensitivity to differences in surface roughness and composition makes remote sensing techniques useful for regional mapping of alluvial deposits. Radar images from the Spaceborne Radar Laboratory and visible wavelength images from the French SPOT satellite were used to determine remote sensing signatures of alluvial fan units for an area in the Kun Lun Mountains of northwestern China. These data were combined with field observations to compare surface processes and their effects on remote sensing signatures in northwestern China and the southwestern United States. Geomorphic processes affecting alluvial fans in the two areas include aeolian deposition, desert varnish, and fluvial dissection. However, salt weathering is a much more important process in the Kun Lun than in the southwestern United States. This slows the formation of desert varnish and prevents desert pavement from forming. Thus the Kun Lun signatures are characteristic of the dominance of salt weathering, while signatures from the southwestern United States are characteristic of the dominance of desert varnish and pavement processes. Remote sensing signatures are consistent enough in these two regions to be used for mapping fan units over large areas.

  4. Architecture of a Coarse-Grained Upper Middle Cambrian Alluvial Delta Dominated by Braidplain and Gilbert-Style Delta Components

    NASA Astrophysics Data System (ADS)

    Pound, K. S.

    2014-12-01

    The ~500-m thick upper Middle Cambrian Lockett Conglomerate was deposited as part of an alluvial delta that includes Gilbert-type mega-crossbeds as well as braidplain conglomerates, and was constructed across an accretionary prism. Internal Lockett Conglomerate architecture indicates at least three phases of progradation are recorded by Gilbert-type, delta-front deposits that are separated by delta-top distributaries and/or braidplain deposits, all of which form discontinuous sheets and lenses, and record aggradation. Evaluation of sedimentary features (particle size and organization, bedding features) allows identification of eight facies within the Lockett Conglomerate; sedimentary features were used to infer transportational and depositional mechanisms. Conglomerate facies HL-1 - HL-8 were assigned to one or more of the following depositional associations: Beachface/shoreface, Deltafront, Alluvial fan, Braidplain (fluvial, unchannelized), Delta-top distributaries, and Mouth-bars. A series of Depositional Packages was identified, and mapped; integration with measured sections allowed development of a facies model for an alluvial delta in which the subaerial component is dominated by the braidplain association, and the subaqueous component by the (Gilbert-type) deltafront association as well as the delta-top distributary and mouthbar associations. Locally, the beachface association marks the transition between the subaqueous and subaerial components of the alluvial delta. Alluvial fan deposits are absent, but the rounded pebbles, cobbles and boulders with a new and distinctive provenance signature indicate derivation from a newly exposed igneous and metamorphic basement, and abrasion during transport through the fluvial (braidplain) system prior to deposition as part of the alluvial delta.

  5. Morphometric Characterization and Classification of Alluvial Fans in Eastern Oman

    NASA Astrophysics Data System (ADS)

    Leuschner, Annette; Mattern, Frank; van Gasselt, Stephan

    2015-04-01

    Morphologic characteristics of alluvial fans are a product of fluvial erosion, transportation and deposition. Consequently, fans have been described and defined on the basis of their shape, their composition, conditions and processes under which they from, their so-called "controlling factors", and their geomorphic and tectonic settings. The aim of our study is to reconstruct the morphologic evolution and to relate it to past and present climate conditions. In order to achieve this, we first characterize alluvial fans based on their climatic settings and conditions and classify them accordingly using satellite image data and digital elevation models. For mapping of different alluvial fan bodies multispectral images of the Landsat Enhanced Thematic Mapper (ETM+) with a scale of 15-30 m/px were utilized. For the detection of morphometric parameters as input data for subsequent hydrological studies digital terrain model data of the Shuttle Radar Topography Mission (SRTM) and the ASTER GDEM with a scale of 90 m/px and 30m, respectively, were used. Using these datasets morphological characteristics, such as sizes of drainage basins, transport areas and areas of deposition derived from spatial semi-automatic analysis, have been computed. The area of Muscat at the Oman Mountains has been selected as a study area because of its size, accessibility and climate conditions and it is considered well-suited for studying the development of alluvial fans and their controlling factors. The Oman Mountains are well-known for the world's largest intact and best exposed obducted ophiolite complex, the Semail Ophiolite. They are today subjected to a mild desert climate (Bwh), in?uenced by the Indian Ocean but they have experienced extensive pluvial periods in the geologic past. Formation of alluvial fans was, therefore, likely triggered by the interplay of increased sediment production caused by high rainfalls with enhanced erosion of hillslopes and transport rates during pluvial periods. Typical morphometric parameters controlled by hydrological conditions are sizes of catchment areas, the morphometry of associated rivers and slope angles as well as sizes of alluvial fans. In order to distinguish the catchment areas, semi-automatized spatial analyses based on DEM data were carried out within a commercial GIS environment. Our analyses generally verify that there is a positive correlation between, e.g., fan areas and sizes of catchment areas as well as between fan areas and lengths of valley lines of associated rivers. Furthermore, our analyses show a negative correlation between average fan slopes and sizes of catchment areas. The observations are in good agreement with previous analyses from other areas we conducted. The applied methodology has shown to be adequate to be compared to and combined with future field investigations. Flow events are dominant in fan evolution, but the way in which alluvial fan systems responded to fluvial environmental conditions differs between systems under different climate conditions. We compared our results with data from other places located in different climate zones around the world. This allows us to constrain boundary conditions and their potential influence on shapes in a more efficient way.

  6. Tectonics and Quaternary sequence development of basins along the active Vienna Basin strike-slip fault

    NASA Astrophysics Data System (ADS)

    Salcher, B.; Lomax, J.; Meurers, B.; Smit, J.; Preusser, F.; Decker, K.

    2012-04-01

    The Vienna Basin strike-slip fault is a continent scale active fault extending over a distance of some 300 km from the Eastern Alps through the Vienna Basin into the Western Carpathians. Sinistral movement causes the formation of several tight Pleistocene strike-slip basins within the older Miocene Vienna Basin. These sub-basins not only have a high relevance for groundwater exploitation but their fault activities depict serious seismic hazards. Basins are filled with fluvial sediments from the Danube and, closer to the Alpine front, with thick alluvial fan deposits. However, knowledge on the stratigraphy and tectonics is sparse and rather limited to the Miocene part of the Vienna Basin as it hosts giant hydrocarbon fields. This study tackles two major questions: (i) What is the effect of Quaternary climatic oscillations and subsidence on the sequence development of the alluvial fans and (ii) what is the deformation style of these basins? To answer (i) we present a series of new OSL ages and biotic data from both, surface and cores, to better constrain the timing of fan activity, fan abandonment but also to constrain the onset of Pleistocene basin formation. For (ii) we utilize information from unparalleled geophysical and geological data. Specifically we utilize industrial Bouguer gravity's derivatives to highlight shallow structures and to compensate for the lag of fault trace information. The integration of geological and geophysical data highlights textbook-like models of strike-slip basins, with typical features like Riedel shears with intervening relay ramps, en-echelon sidewall faults and a cross-basin fault zone delimiting opposite depocenters. The infill reflects a distinct cyclicity with thick sequences of coarse sediments deposited during colder periods and thin sequences of paleosol and flood sediments deposited during warmer periods. Ages indicate main activity around the short peak glacial periods and basin formation starting c. 300 ka ago. The distinct sequence development and the strong contrast to the underlying marine deposits is a very suitable setting to apply geophysical methods constraining basins' deformation style.

  7. Contrasting lithofacies architecture in ring-plain deposits related to edifice construction and destruction, the Quaternary Stratford and Opunake Formations, Egmont Volcano, New Zealand

    NASA Astrophysics Data System (ADS)

    Palmer, Beth A.; Neall, Vincent E.

    1991-11-01

    The early constructional and destructional history of ancestral Egmont Volcano is recorded by variations in lithofacies assemblages and architecture in volcaniclastic deposits making up the southern ring plain. Eruptive periods and edifice construction are recorded by aggradational sequences of debris-flow deposits on the ring plain and numerous tephra deposits preserved on the lower flanks of the volcano. The aggradational sequences represent fairly long-term periods of accumulation when a succession of lahars delivered coarse-grained sediment to the ring plain. Edifice destruction is recorded on the ring plain by deposits of debris-avalanches and associated debris flows. Individual deposits represent rapid (as much as 2.6 km 3), but episodic, sedimentation over large areas (up to 500 km 2) of the ring plain. Sedimentation following these events was slow, with reworked tephra and lignite accumulating over most of the ring plain. Episodes of edifice destruction usually marked the beginning of long-term quiescent intervals or periods of low-frequency eruptive activity. Tephra deposits on the flanks of the volcano are not as abundant as in stratigraphic intervals representing periods of edifice construction.

  8. Quaternary Research Association

    NSDL National Science Digital Library

    The Quaternary Research Association explains that it "exists to promote understanding of the Quaternary Period by publishing field guides, technical guides, and an international journal as well as holding field meetings and speaker meetings." Students and researchers can discover employment, research, grant, meetings, and educational opportunities.

  9. Geomorphological facies reconstruction of Late Quaternary alluvia by the application of fluvial architecture concepts

    NASA Astrophysics Data System (ADS)

    Houben, Peter

    2007-04-01

    This paper investigates the methodical implications, the benefits, and the constraints of applying the fluvial architecture concept to Late Quaternary shallow-subsurface alluvial deposits. The focus is upon a typical small- to mesoscale valley floor of the temperate zone. The studied reach is part of the river Wetter catchment (517 km 2) in central Germany. A large number of studies on Late Quaternary terrestrial paleoenvironmental change of the temperate zone refer to such small- to mesoscale catchments, which are mostly occupied by mixed- to suspended-load rivers. As in many cases mostly coring-based evidence is available, the observation and measurement is limited to lithology and lithofacies boundaries; facies geometry must be inferred. Moreover, in those environments differences in lithofacies are obscured by a significantly reduced range of grain size distributions. An example of an ancient channel belt of Late Glacial to Holocene age serves to delineate the methodical practice and utility of the fluvial architecture approach. Field evidence is obtained from detailed cross-sectional surveys and comprises descriptions of lithofacies, structural, pedogenetical, biotic features, Munsell color, and total organic carbon magnetic volume susceptibility. Cross-sectional lithofacies information is represented by spatially attributed, scaled borehole logs. The example also accentuates the need for applying additional stratigraphical methods such as physical age determination, macrofossil analysis, and tephrological stratigraphy. These methods form the basis to discern stacked channel facies and derive a diachrony of channel forms. Thus, the adapted architecture approach provides a significant surplus of information on channel dimensions, ages, and channel-floodplain interconnectedness. Distinct fluvial landforms such as channels, levees, abandoned channels, swamps, and floodplain flats can be highlighted. A number of methodical constraints are discussed in detail, e.g., the sharpness of channel element geometry and the underlying ordering of bounding surfaces. Moreover, it is shown that the analytical process resembles an iterative looping process that is led by deduction. Many geomorphologists and multi-disciplinary floodplain researchers collect sedimentary data but still neglect utilizing the potential of architectural analysis. The study makes clear that sedimentological approaches used in 'big river' floodplains also apply to small valleys; in fact, the procedures for facies reconstruction need to be adjusted to each individual case study. Alluvial architecture analysis provides the tools to reveal interconnectedness (or disconnectedness) of channel, near-channel, and overbank fluvial landforms, which is essential for a geomorphological understanding of floodplain evolution.

  10. Geometry and evolution of a syntectonic alluvial fan, Southern Pyrenees

    SciTech Connect

    Arminio, J.F. (Maraven S.A., Caracas (Venezuela)); Nichols, G.J. (Univ. of London, Egham, Surrey (United Kingdom))

    1993-02-01

    Syntectonic alluvial fans formed on the northern margin of the Ebro Foreland Basin along the South Pyrenean thrust front during late orogenic thrust movements in the late Oligocene/early Miocene. The present-day geometry, structural relations and sedimentology of one of these fans, the Aguero fan in the province of Huesca, Spain, were studied. Field observations of the architecture of depositional facies and the geometries of syn-tectonic folds and unconformities indicate that the Aguero fan formed as the result of several phases of sedimentation which were primarily controlled by periods of tectonic activity and quiescence. The syntectonic unconformities and growth folds in the fan deposits provide a detailed record of the evolution of a fan adjacent to an active thrust front. Using a computer program to simulate sedimentation and deformation of an alluvial fan it is possible to constrain rates of both sedimentary and tectonic processes by modeling the evolution of the fan body. A facies model for the fan phases indicates that the facies change from proximal (coarse-grained, amalgamated) to distal (finger grained, stacked fining up cycles) in less than 1 km across a fan of radius estimated to be about 2 km.

  11. Volcaniclastic alluvial fan sedimentation, northern Rio Grande rift

    SciTech Connect

    McPherson, J.G.; Waresback, D.B.; Self, S.

    1986-05-01

    The Pliocene Puye Formation is a well-exposed, volcanogenic, alluvial fan sequence 150+ m thick, representing a range of volcaniclastic deposits (proximal, medial, and distal) that may be generated in response to long-lived, multicompositional (basaltic to rhyolitic) volcanism in a rift setting. The deposits are a composite of eruptives (effusives and pyroclastics) and epiclastics (reworked primary volcanics). An almost complete record of source-area volcanics (style, intensity, and composition) is preserved in the volcaniclastic fan deposits, as sedimentation rates were high and basinal subsidence was continuous because of concomitant rift downfaulting. At least eight silicic, primary airfall beds are interstratified through the fan deposits and provide a reliable stratigraphic control for establishing vertical and lateral lithofacies correlations. Proximal (inner fan) lithofacies include voluminous block-and-ash deposits that have downfan facies equivalents as pyroclastic flows and mudflows. Other proximal facies include very coarse clast-bearing debris flows, boulder-rich stream-channel and hyperconcentrated flood-flow deposits, and minor sheet-flood sequences. Medial (midfan) deposits display the greatest variability in lithofacies and provide details of the rate and intensity of volcanism by means of a distinctive vertical lithofacies assemblage: a basal plinian layer, stacked debris flows, and stacked mudflows, capped by a fluvial reworking phase of interstratified stream-channel and sheetflood deposits. Debris flows (clast and matrix rich), mudflows, and hyperconcentrated flood-flow deposits are abundant; the latter show evidence of transformation to mudflows with increasing transport distance, as they incorporate added fines (ash). Sheetflood deposits increase in number and thickness at the expense of stream-channel deposits.

  12. International Union for Quaternary Research

    NSDL National Science Digital Library

    The International Union for Quaternary Research (INQUA) discusses quaternary scientists' investigations "to interpret the changing world of the glacial ages and their impact on our planet's surface environments.". Researchers can find out about INQUA-funded projects, meetings, scientific commissions, and INQUA's two publicaions, Quaternary International, and Quaternary Perspectives.

  13. Quaternary vertebrates from Greenland: A review

    NASA Astrophysics Data System (ADS)

    Bennike, Ole

    Remains of fishes, birds and mammals are rarely reported from Quaternary deposits in Greenland. The oldest remains come from Late Pliocene and Early Pleistocene deposits and comprise Atlantic cod, hare, rabbit and ringed seal. Interglacial and interstadial deposits have yielded remains of cod, little auk, collared lemming, ringed seal, reindeer and bowhead whale. Early and Mid-Holocene finds include capelin, polar cod, red fish, sculpin, three-spined stickleback, Lapland longspur, Arctic hare, collared lemming, wolf, walrus, ringed seal, reindeer and bowhead whale. It is considered unlikely that vertebrates could survive in Greenland during the peak of the last glaciation, but many species had probably already immigrated in the Early Holocene.

  14. Water resources in basin-fill deposits in the Tularosa Basin, New Mexico

    USGS Publications Warehouse

    Orr, B.R.; Myers, R.G.

    1986-01-01

    The Tularosa Basin, a faulted intermontane depression in south-central New Mexico, contains a thick sequence of alluvial and lacustrine deposits of Tertiary and Quaternary age. Most of these sediments are saturated with very saline water. Freshwater supplies (dissolved solids concentration < 1000 mg/L) principally are found in alluvial fans located around the basin margin. On the eastern side of the Tularosa Basin, fresh groundwater supplies are limited to alluvial fan deposits from Grapevine Canyon to about 3 mi south of Alamogordo. Data from surface geophysical surveys indicate that about 1.4 to 2.1 million acre-ft of freshwater may be in storage in this area, not all of which is recoverable. An additional 3.6 to 5.4 million acre-ft of slightly saline water (dissolved solids concentration 1000 to 3000 mg/L) may be in storage in the same area, again not all of which is recoverable. On the western side of the Tularosa Basin, alluvial fans in the vicinity of Rhodes Canyon may contain freshwater. Geophysical data indicate the freshwater zone may be as thick as 1500 ft in places; however, the limited number of wells in this area precludes a precise definition of the volume of freshwater in storage. To the south, freshwater is present in alluvial fans associated with the Ash Canyon drainage system. Geophysical data indicate that perhaps as much as 450,000 acre-ft of freshwater, not all recoverable, may be in storage in this area. Fan deposits between Ash Canyon and Rhodes canyon may contain additional freshwater supplies. Possibly 10.7 million acre-ft of freshwater, not all of which is recoverable, may be in storage on the western side of the Tularosa Basin. Possibly 180 million acre-ft of brine (concentrations of dissolved solids exceeding 35,000 mg/L), not all of which is recoverable, may be in storage in the Tularosa Basin. Information is sparse concerning the capability of saline aquifers in the Tularosa Basin to store and transmit fluid. (Author 's abstract)

  15. Reservoir Characterization, Production Characteristics, and Research Needs for Fluvial/Alluvial Reservoirs in the United States

    SciTech Connect

    Cole, E.L.; Fowler, M.L.; Jackson, S.R.; Madden, M.P.; Raw-Schatzinger, V.; Salamy, S.P.; Sarathi, P.; Young, M.A.

    1999-04-28

    The Department of Energy's (DOE's) Oil Recovery Field Demonstration Program was initiated in 1992 to maximize the economically and environmentally sound recovery of oil from known domestic reservoirs and to preserve access to this resource. Cost-shared field demonstration projects are being initiated in geology defined reservoir classes which have been prioritized by their potential for incremental recovery and their risk of abandonment. This document defines the characteristics of the fifth geological reservoir class in the series, fluvial/alluvial reservoirs. The reservoirs of Class 5 include deposits of alluvial fans, braided streams, and meandering streams. Deposit morphologies vary as a complex function of climate and tectonics and are characterized by a high degree of heterogeneity to fluid flow as a result of extreme variations in water energy as the deposits formed.

  16. Quaternary Glacial Mapping in Western Wisconsin Using Soil Survey Information

    ERIC Educational Resources Information Center

    Oehlke, Betsy M.; Dolliver, Holly A. S.

    2011-01-01

    The majority of soils in the western Wisconsin have developed from glacial sediments deposited during the Quaternary Period (2.6 million years before present). In many regions, multiple advances and retreats have left a complex landscape of diverse glacial sediments and landforms. The soils that have developed on these deposits reflect the nature…

  17. Depositional sequences controlled by high rates of sediment supply, sea-level variations, and growth faulting: the Quaternary Baram Delta of northwestern Borneo

    Microsoft Academic Search

    R. N. Hiscott

    2001-01-01

    The shelf off the Baram Delta is 50–70km wide, and is underlain by 8–9km of post-Eocene upper slope, prodelta, delta-front, fluvial, shelf–shoreface, and estuarine (incised-valley and tidal-embayment) deposits. The shelf break is defined by a prominent fault scarp ?130m below sea level. Beyond, the seabed descends at an average of 2–3° to the Borneo Trough at >2750m depth. The outer-shelf

  18. Grain size and heavy minerals of the Late Quaternary eolian sediments from the Imbituba–Jaguaruna coast, Southern Brazil: Depositional controls linked to relative sea-level changes

    Microsoft Academic Search

    A. O. Sawakuchi; P. C. F. Giannini; C. T. Martinho; A. P. B. Tanaka

    2009-01-01

    The stratigraphic subdivision and correlation of dune deposits is difficult, especially when age datings are not available. A better understanding of the controls on texture and composition of eolian sands is necessary to interpret ancient eolian sediments. The Imbituba–Jaguaruna coastal zone (Southern Brazil, 28°–29° S) stands out due to its four well-preserved Late Pleistocene (eolian generation 1) to Holocene eolian

  19. Combined velocity and depth mapping on developing laboratory alluvial fans

    NASA Astrophysics Data System (ADS)

    Hamilton, P.; Strom, K. B.; Hoyal, D. C.

    2011-12-01

    Large-scale particle image velocimetry (LSPIV) is a nonintrusive method for measuring free-surface velocities using tracer patterns in a sequence of images. This method has been applied in both natural rivers and large-scale hydraulic models (Muste et al., 2008). Here the method is used to map channel and sheet flow velocity during the development of laboratory-scale alluvial fans. Measuring the time and space varying hydraulics on laboratory fans by traditional methods is not practical since flows are quite shallow (~1 cm). Additionally, the highly dynamic environment makes positioning of traditional probe-type instruments difficult and their physical presence could alter autogenic fan evolution. These difficulties can be overcome by using particle image velocimetry techniques. Furthermore, images collected in the LSPIV method can be used to extract flow depth using a calibrated dye-intensity method (Gran and Paola, 2001). This allows for simultaneous measurement of flow velocity and depth everywhere over the fan at any point in time. To validate the method, a set of controlled small-scale experiments were run for depths ranging from 0.2-1.5 cm and velocities from 10-100 cm/sec. Comparison of the LSPIV and dye-intensity method measurements to the known values indicated that the methodology was able to accurately capture simultaneous flow velocity and depth in this range of conditions, i.e., those encountered during the development of laboratory-scale alluvial fans and streams. The method is then used to map the hydraulics associated with various fan processes during development as demonstrated in figure 1. The ability to measure hydraulic properties during fan development is important since physical models provide an arena for observing the time evolution and morphodynamic feedback in depositional systems such as alluvial fans.

  20. Alluvial Diamond Resource Potential and Production Capacity Assessment of Ghana

    USGS Publications Warehouse

    Chirico, Peter G.; Malpeli, Katherine C.; Anum, Solomon; Phillips, Emily C.

    2010-01-01

    In May of 2000, a meeting was convened in Kimberley, South Africa, and attended by representatives of the diamond industry and leaders of African governments to develop a certification process intended to assure that rough, exported diamonds were free of conflictual concerns. This meeting was supported later in 2000 by the United Nations in a resolution adopted by the General Assembly. By 2002, the Kimberley Process Certification Scheme (KPCS) was ratified and signed by both diamond-producing and diamond-importing countries. Over 70 countries were included as members at the end of 2007. To prevent trade in 'conflict' diamonds while protecting legitimate trade, the KPCS requires that each country set up an internal system of controls to prevent conflict diamonds from entering any imported or exported shipments of rough diamonds. Every diamond or diamond shipment must be accompanied by a Kimberley Process (KP) certificate and be contained in tamper-proof packaging. The objective of this study was to assess the alluvial diamond resource endowment and current production capacity of the alluvial diamond-mining sector in Ghana. A modified volume and grade methodology was used to estimate the remaining diamond reserves within the Birim and Bonsa diamond fields. The production capacity of the sector was estimated using a formulaic expression of the number of workers reported in the sector, their productivity, and the average grade of deposits mined. This study estimates that there are approximately 91,600,000 carats of alluvial diamonds remaining in both the Birim and Bonsa diamond fields: 89,000,000 carats in the Birim and 2,600,000 carats in the Bonsa. Production capacity is calculated to be 765,000 carats per year, based on the formula used and available data on the number of workers and worker productivity. Annual production is highly dependent on the international diamond market and prices, the numbers of seasonal workers actively mining in the sector, and environmental conditions, which influence seasonal farming.

  1. Magnitude of late Quaternary left-lateral displacements along the north edge of Tibet

    Microsoft Academic Search

    Gilles Peltzer; Paul Tapponnier; Rolando Armijo

    1989-01-01

    Images taken by the earth observation satellite SPOT of the Quaternary morphology at 18 sites on the 2000-kilometer-long Altyn Tagh fault at the north edge of Tibet demonstrate that it is outstandingly active. Long-term, left-lateral strike-slip offsets of stream channels, alluvial terrace edges, and glacial moraines along the fault cluster between 100 and 400 meters. The high elevation of the

  2. Hydrogeology and simulation of flow between the alluvial and bedrock aquifers in the upper Black Squirrel Creek basin, El Paso County, Colorado

    USGS Publications Warehouse

    Watts, K.R.

    1995-01-01

    Anticipated increases in pumping from the bedrock aquifers in El Paso County potentially could affect the direction and rate of flow between the alluvial and bedrock aquifers and lower water levels in the overlying alluvial aquifer. The alluvial aquifer underlies about 90 square miles in the upper Black Squirrel Creek Basin of eastern El Paso County. The alluvial aquifer consists of unconsolidated alluvial deposits that unconformably overlie siltstones, sandstones, and conglomerate (bedrock aquifers) and claystone, shale, and coal (bedrock confining units) of the Denver Basin. The bedrock aquifers (Dawson, Denver, Arapahoe, and Laramie-Fox Hills aquifers) are separated by confining units (upper and lower Denver and the Laramie confining units) and overlie a relatively thick and impermeable Pierre confining unit. The Pierre confining unit is assumed to be a no-flow boundary at the base of the alluvial/ bedrock aquifer system. During 1949-90, substantial water-level declines, as large as 50 feet, in the alluvial aquifer resulted from withdrawals from the alluvial aquifer for irrigation and municipal supplies. Average recharge to the alluvial aquifer from infiltration of precipitation and surface water was an estimated 11.97 cubic feet per second and from the underlying bedrock aquifers was an estimated 0.87 cubic foot per second. Water-level data from eight bedrock observation wells and eight nearby alluvial wells indicate that, locally, the alluvial and bedrock aquifers probably are hydraulically connected and that the alluvial aquifer in the upper Black Squirrel Creek Basin receives recharge from the Denver and Arapahoe aquifers but-locally recharges the Laramie-Fox Hills aquifer. Subsurface-temperature profiles were evaluated as a means of estimating specific discharge across the bedrock surface (the base of the alluvial aquifer). However, assumptions of the analytical method were not met by field conditions and, thus, analyses of subsurface-temperature profiles did not reliably estimate specific discharge across the bedrock surface. The vertical hydraulic diffusivity of a siltstone and sandstone in the lower Denver confining unit was estimated, by an aquifer test, to be about 8 x 10'4 square foot per day. Physical and chemical characteristics of water from the bedrock aquifers in the study area generally differ from the physical and chemical characteristics of water from the alluvial aquifer, except for the physical and chemical characteristics of water from one bedrock well, which is completed in the Laramie-Fox Hills aquifer. In the southern part of the study area, physical and chemical characteristics of ground water indicate downward flow of water from the alluvial aquifer to the Laramie-Fox Hills aquifer. A three-dimensional numerical model was used to evaluate flow of water between the alluvial aquifer and underlying bedrock. Simulation of steady-state conditions indicates that flow from the bedrock aquifers to the alluvial aquifer was about 7 percent of recharge to the alluvial aquifer, about 0.87 cubic foot per second. The potential effects of withdrawal from the alluvial and bedrock aquifers at estimated (October 1989 to September 1990) rates and from the bedrock aquifers at two larger hypothetical rates were simulated for a 50-year projection period. The model simulations indicate that water levels in the alluvial aquifer will decline an average of 8.6 feet after 50 years of pumping at estimated October 1989 to September 1990 rates. Increases in withdrawals from the bedrock aquifers in El Paso County were simulated to: (1) Capture flow that currently discharges from the bedrock aquifers to springs and streams in upland areas and to the alluvial aquifer, (2) induce flow downward from the alluvial aquifer, and (3) accelerate the rate of waterlevel decline in the alluvial aquifer.

  3. Alluvial diamond resource potential and production capacity assessment of Guinea

    USGS Publications Warehouse

    Chirico, Peter G.; Malpeli, Katherine C.; Van Bockstael, Mark; Diaby, Mamadou; Cissé, Kabinet; Diallo, Thierno Amadou; Sano, Mahmoud

    2012-01-01

    In May of 2000, a meeting was convened in Kimberley, South Africa, by representatives of the diamond industry and leaders of African governments to develop a certification process intended to assure that export shipments of rough diamonds were free of conflict concerns. Outcomes of the meeting were formally supported later in December of 2000 by the United Nations in a resolution adopted by the General Assembly. By 2002, the Kimberley Process Certification Scheme (KPCS) was ratified and signed by diamond-producing and diamond-importing countries. The goal of this study was to estimate the alluvial diamond resource endowment and the current production capacity of the alluvial diamond mining sector of Guinea. A modified volume and grade methodology was used to estimate the remaining diamond reserves within Guinea's diamondiferous regions, while the diamond-production capacity of these zones was estimated by inputting the number of artisanal miners, the number of days artisans work per year, and the average grade of the deposits into a formulaic expression. Guinea's resource potential was estimated to be approximately 40 million carats, while the production capacity was estimated to lie within a range of 480,000 to 720,000 carats per year. While preliminary results have been produced by integrating historical documents, five fieldwork campaigns, and remote sensing and GIS analysis, significant data gaps remain. The artisanal mining sector is dynamic and is affected by a variety of internal and external factors. Estimates of the number of artisans and deposit variables, such as grade, vary from site to site and from zone to zone. This report has been developed on the basis of the most detailed information available at this time. However, continued fieldwork and evaluation of artisanally mined deposits would increase the accuracy of the results.

  4. Spatio-temporal dynamics of nitrogen in river-alluvial aquifer systems affected by diffuse pollution from agricultural sources: Implications for the implementation of the Nitrates Directive

    NASA Astrophysics Data System (ADS)

    Arauzo, M.; Valladolid, M.; Martínez-Bastida, J. J.

    2011-12-01

    SummaryReducing nitrate pollution from diffuse agricultural sources is the major environmental challenge in the two adjacent catchments of the Oja-Tirón and Zamaca rivers (La Rioja and Castilla y León, northern Spain). For this reason, part of their territory was designated a Nitrate Vulnerable Zone (NVZ) according to the Nitrates Directive. The Oja Alluvial Aquifer, the Tirón Alluvial Aquifer and their associated rivers are particularly vulnerable to nitrogen pollution due to the shallow water table, the high permeability of alluvial deposits, interconnections between the alluvial aquifers and surface waters and pressures from agriculture. To this end, nine sampling campaigns, organised on a semi-annual basis and focused on the rivers and alluvial aquifers of the two catchments, were carried out from April 2005 to April 2009. The main objectives of the study were: (1) to investigate the chemical forms of nitrogen in river-alluvial aquifer systems of the Oja-Tirón and Zamaca catchments, (2) to improve our understanding of the spatio-temporal patterns of nitrogen distribution in the alluvial aquifers and associated rivers by integrating hydrochemical data and hydrogeological and environmental parameters, (3) to estimate the amount of nitrogen exported from the rivers and alluvial aquifers to the River Ebro, and (4) to evaluate the suitability of the current method of designating NVZs in the area. High groundwater flow velocities in the upper alluvial zones favoured the advective transport of nitrate and generated a dilution effect. In these areas, inter-annual variations in nitrate concentrations were observed related to precipitation and N-input from agriculture. However, low flow velocities favoured processes of accumulation in the lower alluvial zones. Our results demonstrated that the entire alluvial surface was highly vulnerable, according to dynamics of the nitrogen in the river-alluvial aquifer systems being studied. The amount of nitrogen exported from these river-alluvial aquifer systems to the River Ebro was estimated at 2.4 ± 0.2 kt year -1. Findings from this investigation highlight the need to include the alluvial area corresponding to the Tirón aquifer as a NVZ, particularly as the Tirón sub-catchment provides more than half of the nitrogen exported from the River Tirón to the River Ebro. Based in these results, at least the entire alluvial surface in the study area should be considered a NVZ in order to address the recovery of water quality.

  5. Nucleation of Waterfalls at Fault Scarps Temporarily Shielded By Alluvial Fan Aggradation.

    NASA Astrophysics Data System (ADS)

    Malatesta, L. C.; Lamb, M. P.

    2014-12-01

    Waterfalls are important components of mountain river systems and they can serve as an agent to transfer tectonic, climatic, or authigenic signals upstream through a catchment. Retreating waterfalls lower the local base level of the adjacent hillslopes, and temporarily increase sediment delivery to the fluvial system. Their creation is often attributed to seismic ruptures, lithological boundaries, or the coalescence of multiple smaller steps. We explore here a mechanism for the nucleation of waterfalls that does not rely on sudden seismic slip but on the build-up of accumulated slip during periods of fault burial by fluvial aggradation. Alluvial fans are common features at the front of mountain ranges bound by normal or thrust faults. Climate change or internal forcing in the mountain catchment modifies the equilibrium slope of alluvial fans. When alluvial fans aggrade, they shield the active fault scarp from fluvial erosion allowing the scarp to grow undisturbed. The scarp may then be exposed when the channel incises into the fan exposing a new bedrock waterfall. We explore this mechanism analytically and using a numerical model for bedrock river incision and sediment deposition. We find that the creation of waterfalls by scarp burial is limited by three distinct timescales: 1) the critical timescale for the scarp to grow to the burial height, 2) the timescale of alluvial re-grading of the fan, and 3) the timescale of the external or internal forcing, such as climate change. The height of the waterfall is controlled by i) the difference in equilibrium alluvial-fan slopes, ii) the ratio of the respective fan and catchment sizes, iii) the catchment wide denudation rate, and iv) the fault slip rate. We test whether an individual waterfall could be produced by alluvial shielding of a scarp, and identify the tectonic, climatic, or authigenic nature of waterfalls using example field sites in the southwest United States.

  6. Geomorphological evolution of the Tilcara alluvial fan (Jujuy Province, NW Argentina): Tectonic implications and palaeoenvironmental considerations

    NASA Astrophysics Data System (ADS)

    Sancho, Carlos; Peña, José Luis; Rivelli, Felipe; Rhodes, Ed; Muñoz, Arsenio

    2008-07-01

    The development and evolution of the Tilcara alluvial fan, in the Quebrada de Humahuaca (Andean Eastern Cordillera, NW Argentina), has been analysed by using geomorphological mapping techniques, sedimentological characterisation of the deposits and OSL chronological methods. It is a complex segmented alluvial fan made up of five evolutionary stages (units Qf1, Qf2, Qf3, Qf4 and Qf5) developed under arid climatic environments as well as compressive tectonic conditions. Segmentation processes, including aggradation/entrenchment cycles and changes in the location of the depositional lobe, are mainly controlled by climatic and/or tectonic changes as well as channel piracy processes in the drainage system. Alluvial fan deposits include debris flows, sheet flows and braided channel facies associated with high water discharge events in an arid environment. The best mean OSL age estimated for stage Qf2 is 84.5 ± 7 ka BP. In addition, a thrust fault affecting these deposits has been recognized and, as a consequence, the compressive tectonics must date from the Upper Pleistocene in this area of the Andean Eastern Cordillera.

  7. Grain size and heavy minerals of the Late Quaternary eolian sediments from the Imbituba-Jaguaruna coast, Southern Brazil: Depositional controls linked to relative sea-level changes

    NASA Astrophysics Data System (ADS)

    Sawakuchi, A. O.; Giannini, P. C. F.; Martinho, C. T.; Tanaka, A. P. B.

    2009-12-01

    The stratigraphic subdivision and correlation of dune deposits is difficult, especially when age datings are not available. A better understanding of the controls on texture and composition of eolian sands is necessary to interpret ancient eolian sediments. The Imbituba-Jaguaruna coastal zone (Southern Brazil, 28°-29° S) stands out due to its four well-preserved Late Pleistocene (eolian generation 1) to Holocene eolian units (eolian generations 2, 3, and 4). In this study, we evaluate the grain-size and heavy-mineral characteristics of the Imbituba-Jaguaruna eolian units through statistical analysis of hundreds of sediment samples. Grain-size parameters and heavy-mineral content allow us to distinguish the Pleistocene from the Holocene units. The grain size displays a pattern of fining and better sorting from generation 1 (older) to 4 (younger), whereas the content of mechanically stable (dense and hard) heavy minerals decreases from eolian generation 1 to 4. The variation in grain size and heavy-mineral content records shifts in the origin and balance (input versus output) of eolian sediment supply attributable mainly to relative sea-level changes. Dunefields submitted to relative sea-level lowstand conditions (eolian generation 1) are characterized by lower accumulation rates and intense post-depositional dissection by fluvial incision. Low accumulation rates favor deflation in the eolian system, which promotes concentration of denser and stable heavy minerals (increase of ZTR index) as well as coarsening of eolian sands. Dissection involves the selective removal of finer sediments and less dense heavy minerals to the coastal source area. Under a high rate of relative sea-level rise and transgression (eolian generation 2), coastal erosion prevents deflation through high input of sediments to the coastal eolian source. This condition favors dunefield growth. Coastal erosion feeds sand from local sources to the eolian system, including sands from previous dunefields (eolian generation 1) and from drowned incised valleys. Therefore, dunefields corresponding to transgressive phases inherit the grain-size and heavy-mineral characteristics of previous dunefields, leading to selective enrichment of finer sands and lighter minerals. Eolian generations 3 and 4 developed during a regressive-progradational phase (Holocene relative sea level highstand). The high rate of sediment supply during the highstand phase prevents deflation. The lack of coastal erosion favors sediment supply from distal sources (fluvial sediments rich in unstable heavy minerals). Thus, dunefields of transgressive and highstand systems tracts may be distinguished from dunefields of the lowstand systems tract through high rates of accumulation (low deflation) in the former. The sediment source of the transgressive dunefields (high input of previously deposited coastal sands) differs from that of the highstand dunefields (high input of fluvial distal sands). Based on this case study, we propose a general framework for the relation between relative sea level, sediment supply and the texture and mineralogy of eolian sediments deposited in siliciclastic wet coastal zones similar to the Imbituba-Jaguaruna coast.

  8. Tertiary and Quaternary Research with Remote Sensing Methods

    NASA Technical Reports Server (NTRS)

    Conel, J. E.

    1985-01-01

    Problems encountered in mapping the Quaternary section of the Wind River Region using remote sensing methods are discussed. Analysis of the stratigraphic section is a fundamental aspect of the geologic study of sedimentary basins. Stratigraphic analysis of post-Cretaceous rocks in the Wind River Basin encounters problems of a distinctly different character from those involved in studying the pre-Cretaceous section. The interior of the basin is predominantly covered by Tertiary and Quaternary sediments. These rocks, except on the basin margin to the north, are mostly flat lying or gently dipping. The Tertiary section consists of sandstones, siltstones, and tuffaceous sediments, some variegated, but in general poorly bedded and of great lithologic similarity. The Quaternary sediments consist of terrace, fan, and debris tongue deposits, unconsolidated alluvium occupying the bottoms of modern watercourses, deposits of eolian origin and tufa. Terrace and fan deposits are compositionally diverse and reflect the lithologic diversity of the source terranes.

  9. Tectonically induced climate and its control on the distribution of depositional systems in a continental foreland basin, Cloverly and Lakota Formations (Lower Cretaceous) of Wyoming, U.S.A

    Microsoft Academic Search

    William S. Elliott Jr.; Lee J. Suttner; Lisa M. Pratt

    2007-01-01

    Continental sediments of the Cloverly and Lakota Formations (Lower Cretaceous) in Wyoming are subdivided into three depositional systems: perennial to intermittent alluvial, intermittent to ephemeral alluvial, and playa. Chert-bearing sandstones, conglomerates, carbonaceous mudrocks, blocky mudrocks, and skeletal limestones were deposited by perennial to intermittent alluvial systems. Carbonaceous mudrocks contain abundant wood fragments, cuticle and cortical debris, and other vascular plant

  10. Alluvial Fan, Rocky Mountain National Park

    USGS Multimedia Gallery

    The Alluvial Fan is a fan-shaped area of disturbance in Rocky Mountain National Park. It was created on July 15, 1982, when the earthen Lawn Lake Dam above the area gave way, flooding the Park and nearby town of Estes Park with more than 200 million gallons of water. Enormous boulders were displaced...

  11. Arsenate adsorption by unsaturated alluvial sediments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Arsenate adsorption as a function of solution arsenic concentration and solution pH was investigated on five alluvial sediments from the Antelope Valley, Western Mojave Desert, California. Arsenate adsorption increased with increasing solution pH, exhibited a maximum around pH 4 to 5, and then decr...

  12. Changes in vegetation and drainage density as controlling factors in the episodicity of Quaternary sediment flux: southwestern United States and Bolivian Eastern Cordillera

    NASA Astrophysics Data System (ADS)

    Barnes, J.; Pelletier, J. D.

    2001-12-01

    Piedmont geomorphic surfaces in the southwestern U.S. primarily represent cut-and-fill cycles resulting from variations in sediment supply from adjacent mountain catchments. Although sparse, precise age control supports the hypothesis that sediment supply in the southwestern U.S. can increase by an order of magnitude during Quaternary humid-to-arid transitions recognized in high-resolution paleoclimatic proxies. As an example, this episodicity is quantified with a time series of sediment flux for the central Gila Mountains, southwestern Arizona, where paleosurfaces outcrop in the modern channel bank, permitting an estimate of deposit volume in conjunction with high-resolution photogrammetric DEMs. Age control is provided by a new method of surface exposure dating based on 3D hillslope diffusion adjacent to gullies penetrating the surface. We propose that episodes of piedmont alluviation result from an increase in drainage density resulting from climatically-induced vegetative successions from mature woodland vegetation to desert shrubs that excavate large amounts of hillslope colluvium stored during the previous humid interval. Analogous vegetative shifts occur in the Bolivian Eastern Cordillera (EC). Field observations and analyses of topographic maps and LANDSAT images suggest that the longitudinal profiles of the major rivers of the EC are dominated by an order-of-magnitude increase in Plio-Quaternary hillslope erosion in the elevation zone between approximately 2.5 and 3.5 kilometers above sea level corresponding to glacial-interglacial vegetational successions from Andean forest (glacial) to Paramo grasslands (interglacial). These vegetation changes resulted in rapid fluctuations in drainage density responsible for a large increase in transport rates that alluviated major valleys and enhanced bedrock incision rates downstream. Areas above and below this elevation have perennial grassland and forest, respectively, whose long-term vegetational stability has resulted in low erosion rates compared with the intermediate elevation zone. These studies suggest that fluctuations in drainage density driven by vegetative shifts between glacial and interglacial times may be the dominant mechanism of Quaternary sediment production in unglaciated terrain.

  13. Abo Formation alluvial facies and Associated Basin Fill, Sacramento Mountains, New Mexico

    Microsoft Academic Search

    Stephen W. Speer

    1986-01-01

    Outcrops of the Abo Formation (Wolfcampian to early Leonardian age) in the Sacramento Mountains of south-central New Mexico record the evolution of a dry alluvial fan system as it was deposited off the pedernal uplift into the Orogrande basin. The location and orientation of present-day outcrops allow us to observe an inferred east-to-west transverse facies tract consisting of: (1) proximal

  14. Quaternary Research Center

    NSDL National Science Digital Library

    "The Quaternary Research Center (QRC) fosters interdisciplinary research on the last two million years of the global environment: a time which encompasses massive, abrupt changes of climate, sea level, global biota and ice extent, as well the evolution of humans and the advent of civilization." Divided into six laboratories, the University of Washington's Center studies Cosmogenic Isotopes, Stable Isotopes, Old Quaternary Isotopes, Periglacial environments, quaternary ecology, paleoecology, and remote sensing. Researchers can find a tremendous amount of isotope, carbon dioxide, and chemistry data on the Taylor Dome, a part of the East Antarctic ice sheet. Students and educators can read papers by the center covering topics such as interactions among climate, surface, and tectonics; and glaciations and climate variations in the Pacific Northwest.

  15. Quaternary shorelines of the broader area of Cape Maleas - Neapolis - Elafonissos Isl. (SE Peloponnese)

    NASA Astrophysics Data System (ADS)

    Karymbalis, Efthimios; Gaki-Papanastassiou, Kalliopi; Papanastassiou, Dimitris; Tsodoulos, Ioannis; Tsivgoulis, Nikolaos; Tsanakas, Konstantinos; Valkanou, Kanella

    2015-04-01

    The aim of this study is to provide information about the landscape evolution of the broader area of Cape Maleas - Neapolis - Elafonissos Isl. during the Quaternary. In order to investigate the geomorphic evolution of the study area the uplifted coastal landforms, such as shore platforms, notches and remnants of marine terraces, were studied in detail through extensive field-work using topographic diagrams at a scale of 1:5,000, obtained from the Hellenic Military Geographical Service. Additionally, a spatial database was constructed derived from analogue topographic maps at various scales (1:50,000 and 1:5,000), geological maps (1:50,000 maps of IGME), aerial photographs and Google earth images using GIS techniques. The study area is located in SE Peloponnese in a particularly tectonically active area. Geodynamic processes in the region, which is part of the Hellenic island arc, are related to the active subduction of the African lithosphere beneath the Eurasian plate. The Paleozoic basement of the study area consists of geological formations of the geotectonic units of Arna, Tripolis, and Pindus. The Alpine basement is overlain by extensive outcrops of Pliocene and Pleistocene deposits. Upper Pliocene to Lower Pleistocene formations are composed of marine - lacustrine deposits which are mainly pelites, sandstones, conglomerates, calcarenites and carbonate rocks with red algae whereas Pleistocene formations consist of fluvioterrential deposits (clay, sands, loams and angular rock fragments). The Holocene deposits consist of talus cones, scree, and unconsolidated alluvial deposit, eluvial mantle materials and coastal sand dunes along the N, NE and S shoreline of Elafonissos Isl. as well as at Cape Punta. The general trend of the faults in the study area is mainly NW-SE with some secondary ones having NE-SW direction. Along the coast between Cape Koulendi and Cape Maleas, uplifted geomorphological features were mapped, including marine terraces, shore platforms and marine notches. Remnants of Quaternary marine terraces have also been identified at several locations on the Elafonissos Isl. The marine terraces are imprinted into pre-existing Pleistocene marine - lacustrine formations and only a few of them have a thin sandstone caprock. The uplifted Quaternary marine terraces are excellent morphological markers and have been used worldwide to recognize past sea-level changes. Their correlation with the main interglacial high-stands can be done only in areas where a continuous uplift at a regional scale exists combined by dating their exposure. Selected samples were collected for OSL dating in order to correlate the terraces in space and time. The detailed field geomorphological mapping of the study area revealed a sequence of seven to eight marine terraces, according their location, ranging in elevations from 2 to 180m. Based on the raised coastal features of the study area it becomes evident that the prevailing tectonic movement is positive (emergence) during the Pleistocene and Holocene periods. The occurrence of the terraces at different elevations supports the suggestion that the study area is composed by different tectonic blocks moving disparately.

  16. Synthesis of Late Cretaceous-Quaternary tectonic, sedimentary and magmatic processes and basin formation related to episodic subduction-collision in the easternmost Mediterranean region

    NASA Astrophysics Data System (ADS)

    Robertson, Alastair; Kinnaird, Timothy; McCay, Gillian; Palamakumbura, Romesh; Tasl?, Kemal

    2015-04-01

    Mesozoic oceanic crust of the easternmost Mediterranean has experienced northwards subduction during Late Cretaceous-Cenozoic, either continuously or discontinuously based on kinematic evidence. Much of the existing information on sedimentation within the easternmost Mediterranean oceanic basin comes from the non-emplaced continental margins of the Levant and North Africa. In addition, sedimentary basins related to plate convergence are recorded along the northern margin of the Southern Neotethyan ocean, mainly in the Kyrenia Range of northern Cyprus and its extension into the Misis Mountains of southern Turkey, coupled with the adjacent submerged areas. In a setting of only incipient continental collision such as the easternmost Mediterranean the sedimentary basins would be expected to remain entirely submarine. In contrast, the Kyrenia Range has been strongly uplifted and subaerially exposed during Late Pliocene-Quaternary time. This allows the recognition of a number of discrete phases of sedimentary basin formation: 1. Late Cretaceous (Campanian-Maastrichtian): silicic volcanism to create a subaqueous volcaniclastic apron; 2. Maastrichtian-Paleocene: pelagic carbonate deposition interspersed with proximal gravity flows and within-plate type alkaline volcanics; 3. Early Eocene: large-scale sedimentary melange (olistostrome) emplacement; 4. Late Eocene-Late Miocene: terrigenous gravity-flow deposition in a deep-water fault dissected 'fore arc' setting. Initial, Late Eocene non-marine coarse clastic alluvial fan deposition was succeeded by Oligocene-Miocene deep-marine siliciclastic gravity flow deposits, fining and shallowing upwards during the Late Miocene; 5. Messinian: localised precipitation of evaporites in small fault-controlled basins; 6. Pliocene: shallow-marine siliciclastic-carbonate deposition in a shelf-depth, overall regressive setting; 7. Latest Pliocene to mid-Pleistocene: gravitational accumulation of coarse talus along a strongly uplifting subaerial lineament; 8. Mid-Late Quaternary: gradual tectonic uplift giving rise to a flight of shallow marine to non-marine terrace deposits, that were also influenced by eustatic sea-level fluctuations and climatic change. The stages of basin development were punctuated by four main episodes of compression/uplift. A. Late Miocene underthrusting/metamorphism/exhumation; B. Mid-Eocene southwards thrusting; C. Late Miocene southward thrusting/left-lateral transpression; D. Late Pliocene-Mid Quaternary tectonic uplift. In a setting of continuing plate convergence why did the nature of sedimentation change so dramatically through time? The deformation front between the Kyrenia Range and the Troodos Massif is delineated by the Ovgos Fault which shows an episodic development including Late Miocene compression (transpression) and Quaternary left-lateral strike slip. The Late Cretaceous volcanogenic rocks relate to a phase of regional arc magmatism also documented in SE Turkey. Subduction appears to have slowed or ceased during the Maastrichtian-Palaeocene while the active margin experienced extension or transtension. Following final closure of a Tethyan oceanic basin further north ('northern Neotethys') subduction appears to have relocated southwards and re-activated/accelerated during the Early Eocene triggering large-scale collapse of the over-riding plate and olistostrome formation. Diachronous continental collision was in progress during Early Miocene causing strong uplift of the over-riding plate, intense erosion and voluminous siliciclastic sediment supply to a fore-arc type basin in the N Cyprus-Misis area (becoming foreland basin further east, in SE Turkey). The Pliocene was characterised by eastward 'tectonic escape' of the Anatolian plate towards the Aegean and this allowed relatively fine-grained deposition to accumulate along the former convergent continental margin in northern Cyprus and adjacent areas (e.g. Mesaoria basin). The dramatic late Pliocene to mid-Quaternary uplift of the Kyrenia-Misis lineament, plus the Troodos massif to the south, can be explaine

  17. Fire, Holocene Climate Change, and Geomorphic Response Recorded in Alluvial Fan Sediments

    NASA Astrophysics Data System (ADS)

    Pierce, J. L.; Meyer, G. A.

    2004-12-01

    Alluvial fan stratigraphic sequences record fire history in charcoal-rich deposits and buried burned soil surfaces. Deposit characteristics provide information about the magnitude of fire-related sedimentation events and severity of associated fires, and radiocarbon-dating of charcoal establishes the timing of fires. Unlike lakes, alluvial fans are ubiquitous in mountain environments. Although alluvial-fan fire records lack the annual resolution of tree-ring records, compilation of data from many alluvial fan sites provides a statistical sample of fire timing and approximate severity that can be related to climate variations over centennial to millennial timescales. We examine alluvial fan records from xeric Pinus ponderosa-dominated forests of central Idaho, and compare them with similar records from cooler, high-elevation Pinus contorta-dominated forests of Yellowstone National Park. Identification of charcoal macrofossils from Idaho fan deposits limits inbuilt age errors in radiocarbon dating, and shows that similar forest compositions have existed over the last ca. 4000 years in the fan drainage basins. Limited data from ca. 4000-7000 yr ago suggest that Pinus ponderosa was either sparse or absent in the 4 basins represented. Large fire-related debris flows in both Idaho and Yellowstone indicate severe fires during the ca. 1050-750 cal yr BP Medieval Climatic Anomaly (MCA), which included widespread and severe western US droughts. Another such episode 2700-1600 cal yr BP is less prominent in the Idaho record. Numerous small, fire-induced sedimentation events in Idaho ca. 350-500 (Little Ice Age), 1200-1400, and 2800-3000 cal yr BP likely indicate frequent low- to mixed-severity fires, and coincide with indicators of generally cool, moist conditions in the western USA and North Atlantic, and with minimal fire activity in Yellowstone. We infer that these effectively wetter periods allow greater grass growth, fueling frequent surface fires in ponderosa forests, but limiting fires in general in the effectively wetter forests of Yellowstone. Maxima in dated small events may relate to significant droughts within these intervals, e.g. in the late AD 1500s, but widespread severe fires are not indicated. Alluvial-fan records add to data from other charcoal-based proxy records of fire that indicate the importance of centennial- to millennial-scale climate change in modulating fire activity and geomorphic response in conifer forests over the Holocene.

  18. Interaction of fine sediment with alluvial streambeds

    USGS Publications Warehouse

    Jobson, H.E.; Carey, W.P.

    1989-01-01

    An alluvial streambed can have a large capacity to store fine sediments that are extracted from the flow when instream concentrations are high and it can gradually release fine sediment to the flow when the instream concentrations are low. Several types of storage mechanisms are available depending on the relative size distribution of the suspended load and bed material, as well as the flow hydraulics. -from Authors

  19. Pleistocene calcrete deposits from southern Spain as indicators of climatic conditions and tectonic activity

    NASA Astrophysics Data System (ADS)

    Herrero, Maria J.; Insua-Arevalo, Juan M.; Garcia-Mayordomo, Julian; Martin-Banda, Raquel

    2014-05-01

    Quaternary calcrete horizons are common weathering products in arid and semi-arid regions of southern Spain. We have analysed a calcrete profile developed within poorly sorted gravels of an alluvial fan. These deposits were sourced from the Carrascoy Range, a fault generated mountain front located in the Internal Zones of the Betic Cordillera (South Spain). During the Pleistocene the climate in southern Spain was dry, either in the form of semi-arid/arid conditions or as seasonal moisture deficits. Alluvial channel incision trends appeared to be disrupted by episodes of alluvial aggradation produced during cold and dry glacial periods. At the top of the aggradational phases, pedogenic processes operated profusely, and, as a result, several calcretes (stage V mature calcrete profiles) were formed. We have analysed one of these calcrete profiles that appears subvertical within the forelimb of a regional fold in relation to the Carrascoy Fault activity. The calcrete consist of a densely cemented hardpan horizon (20 to 40 cm thick) overlain by a thin, 2-cm thick laminar crust. Below the hardpan horizon, carbonate concentrations gradually decrease to clast-coating textures. Calcretes form progressively and a wide range of carbonate phases occur within a single horizon, being the laminar crust the final stage of evolution within a mature pedogenic calcrete deposit, and, therefore, the carbonate within it postdates all the cement phases within the profile. The location of the latest cement phase of the calcrete deposit has been estimated by microscopic observations (to establish their suitability for dating) together with a detailed sedimentological analysis of the calcrete profile in the field. The laminar crust consists of less than 1 mm thick laminae characterized by the alternation of layers of micrite and layers of micrite with ooids, detrital grains and clays indicating environmental conditions in which sedimentation rates were low and episodic. By using radiometric 232Th/238U dating methods we obtain an age of formation of the laminar crust of ~209 Ka (upper part of the Middle Pleistocene). This age corresponds to the warm stage 7c within the glacial Riss period. As pointed out before, the studied calcrete appears subvertical as a result of the activity of the Carrascoy Fault, and, therefore, the fault was active only after the calcrete was formed. Our study permits, as well, to reliably asses the timing of changes in alluvial processes, to characterized this part of the stratigraphic succession as corresponding to an arid to semi-arid environment, and to conclude that this particular calcrete was developed during a relative European warm period within a glacial stage.

  20. Exploring the use of weathering indexes in an alluvial fan chronology

    NASA Astrophysics Data System (ADS)

    Hardenbicker, Ulrike; Watanabe, Makiko; Kotowich, Roberta

    2015-04-01

    Alluvial fan sediments can act as an archive of local environmental history. Two borehole cores (FN 350 cm and AG 850cm) from Holocene alluvial fans located in the Qu'Appelle Valley in southern Saskatchewan were analyzed in order to identify how changes in land use of upland catchment plateaus modified the pattern and rate of sediment delivery to the fan. Due to the lack of material for radiometric dating a chronology of depositional events within the alluvial fans was established by using lithostratigraphy data of soils and sediments. In order to establish a more detailed relative chronology we evaluated if weathering indexes (the Parker Index, the CaO/ZrO2 molar ratio, the Product Index) originally developed for studies of in situ weathering of bedrock, are suitable to assess sediment weathering within alluvial fan sediments. To quantify the degree of weathering within the sediment samples the three indexes of weathering were calculated using the proportions of elements measure by Energy Dispersive X-ray Spectroscopy and there is an inverse relationship between weathering index and sample age. For further statistical analyses the fan sediments were classified into three groups: a sheet flow facies of well sorted silt loam and sandy loam textures, bed load facies characterized by high sand and gravel content and layers with high organic matter in combination with higher clay content indicative of in situ weathering and soil development. First results show that the Product Index may be the most suitable weathering index to indicate weathering or input of less weathered sediment within the sheet flow and bed load facies. In general, the weathering indexes do not take into account complexities of the weathering processes nor the overall environmental conditions in an alluvial fan. But chemical weathering indexes accompanied by geophysical and geo-chemical information have value, especially when the amount of sample material is limited.

  1. Long-term interactions between man and the fluvial environment - case of the Diyala alluvial fan, Iraq

    NASA Astrophysics Data System (ADS)

    Heyvaert, Vanessa M. A.; Walstra, Jan; Mortier, Clément

    2014-05-01

    The Mesopotamian alluvial plain is dominated by large aggradading river systems (the Euphrates, Tigris and their tributaries), which are prone to avulsions. An avulsion can be defined as the diversion of flow from an existing channel onto the floodplain, eventually resulting in a new channel belt. Early civilizations depended on the position of rivers for their economic survival and hence the impact of channel shifts could be devastating (Wilkinson 2003; Morozova 2005; Heyvaert & Baeteman 2008). Research in the Iranian deltaic part of the Mesopotamian plain has demonstrated that deliberate human action (such as the construction of irrigation canals and dams) triggered or obstructed the alluvial processes leading to an avulsion on fluvial megafans (during preconditioning, triggering and post-triggering stages) (Walstra et al. 2010; Heyvaert et al. 2012, Heyvaert et al.2013). Thus, there is ample evidence that the present-day alluvial landscapes in the region are the result of complex interactions between natural and anthropogenic processes. Here we present a reconstruction of the Late Holocene evolution of the Diyala alluvial fan (one of the main tributaries of the Tigris in Iraq), with particular attention to the relations between alluvial fan development, changes in channel pattern, the construction of irrigation networks and the rise and collapse of societies through historic times. The work largely draws on the use of remote sensing and GIS techniques for geomorphological mapping, and previously published archaeological field data (Adams 1965). By linking archaeological sites of known age with traces of ancient irrigation networks we were able to establish a chronological framework of alluvial activity of the Diyala alluvial fan. Our results demonstrate that centralized and technologically advanced societies were able to maintain a rapidly aggradading distibutary channel system, supplying water and sediment across the entire alluvial fan. As a consequence, during these periods (Parthian, Sasanian and again in modern times), significant human modification of the landscape took place. Periods of societal decline are associated with reduced human impact and the development of a single-threaded incising river system. Adams, R.M. (1965). Land behind Baghdad: A history of settlement on the Diyala plains. University of Chicago Press, Chicago, Illinois. Heyvaert, V.M.A. & Baeteman, C. (2008). A Middle to Late Holocene avulsion history of the Euphrates river: a case study from Tell ed-D-er, Iraq, Lower Mesopotamia. Quaternary Science Reviews, 27, 2401-2410. Heyvaert, V. M. A., Walstra, J., Verkinderen, P., Weerts, H. J. T. & Ooghe, B. (2012). The role of human interference on the channel shifting of the river Karkheh in the Lower Khuzestan plain (Mesopotamia, SW Iran). Quaternary International, 251, 52-63. Heyvaert, V.M.A., Walstra, J., Weerts, H.J.T. (2013). Human impact on avulsion and fan development in a semi-arid region: examples from SW Iran. Abstractbook of the 10th International Fluvial Sedimentology Conference, July 2013,Leeds, United Kingdom. Morozova, G.S. (2005). A review of Holocene avulsions of the Tigris and Euphrates rivers and possible effects on the evolution of civilizations in lower Mesopotamia. Geoarchaeology, 20, 401-423. Walstra, J., Heyvaert, V. M. A. & Verkinderen, P. (2010). Assessing human impact on alluvial fan development: a multidisciplinary case-study from Lower Khuzestan (SW Iran). Geodinamica Acta, 23, 267-285. Wilkinson, T.J. (2003). Archaeological Landscapes of the Near East. The University of Arizona Press, Tucson, Arizona.

  2. Quaternary fossil fauna of South Canterbury, South Island, New Zealand

    Microsoft Academic Search

    T. H. Worthy

    1997-01-01

    This study documents the Late Quaternary fossil fauna from 59 fossil sites in the South Canterbury downlands, South Island, New Zealand. Twenty?seven sites were predator accumulations attributed to laughing owls, two were accumulated by falcons, two were swamp sites, and the rest were pitfalls or rockshelter deposits. A total of 60 indigenous species of birds, one bat, three rodents, one

  3. Effects of Quaternary Sea Level Cycles on Strontium in Seawater

    Microsoft Academic Search

    Heather M Stoll; Daniel P Schrag

    1998-01-01

    The effects of Quaternary sea level changes on the Sr budget of the ocean are investigated using coupled numerical models of the seawater Sr and Ca budgets. Glacial\\/interglacial sea level cycles influence the Sr concentration of seawater directly through the periodic exposure and weathering of aragonite on continental shelves and indirectly by modulating the location and extent of carbonate deposition

  4. Are the topsoil structures relevant indicators of alluvial soil evolution ?

    NASA Astrophysics Data System (ADS)

    Salomé, Clémence; Le Bayon, Renée.-Claire; Guenat, Claire; Hallaire, Vincent; Bullinger Weber, Géraldine; Verrecchia, Eric

    2010-05-01

    Floodplains contain a wide range of all steps of soil evolution, which are relevant in order to study the initial steps of soil structuring. Alluvial soils exhibit characteristics of both sediment and / or inherited soil deposition, and in situ soil formation resulting in different types of soil structure, especially in the topsoil layers. In calcareous alluvium deposits, the structuration processes of the topsoil are fast resulting in different structures. In this context, our aim is to verify if these topsoil structures, at macroscopic and microscopic scales, are relevant indicators of in situ soil evolution in a carbonate-rich and calcium saturated environment. We hypothesise that along a soil-vegetation stabilisation gradient both macroscopic and microscopic structures of topsoil reflect this in situ soil evolution. Along this evolutionary gradient the type of structure changes and becomes more stable and widespread within the topsoil. We characterize the topsoil structure in three different vegetation types from the pioneer stage (willow vegetation) on new sediment deposits (carbonate-rich FLUVIOSOLS BRUTS according to the Sound Reference base for soils, 1998) to mature forests (beech, ash, spruce) on stable soils (carbonate-rich FLUVIOSOLS TYPIQUES) at three different altitudes (subalpine to hill levels). In order to evaluate the heterogeneity within each site and between them three replicates are made resulting in a total of 27 soil samples. At the macroscopic scale, topsoil structure is described based on morphological and macroscopic descriptions (humus form, type and size of structure) as well as structure stability (Mean Weight Diameter, MWD) and water stable macro aggregates (WSA%) according to Kemper and Rossenau (1986). At the microscopic scale, polished slabs (dimension of 7cm X 10 cm and 0.5 cm in thickness) are used to quantify pore space using a morphological approach and 2D image analysis. After binarization of the image, leading to the detection and quantification of the soil porosity, a multi fractal algorithm is applied in order to characterize the pores by the slope value of the regression line between the frequencies and their associated amplitudes. In addition, the pore size distribution is described using moments of the third and the fourth orders applied on the pore cumulative curve (pore size vs frequency). These holistic parameters of the structure can be compared with other evolution indicators (e.g. vegetation stage, soil type, structural stability) and are pertinent to evaluate the stage of the humiferous topsoil evolution. They can be considered as relevant indicators of in situ alluvial soil evolution.

  5. Alluvial and bedrock aquifers of the Denver Basin; eastern Colorado's dual ground-water resource

    USGS Publications Warehouse

    Robson, Stanley G.

    1989-01-01

    Large volumes of ground water are contained in alluvial and bedrock aquifers in the semiarid Denver basin of eastern Colorado. The bedrock aquifer, for example, contains 1.2 times as much water as Lake Erie of the Great Lakes, yet it supplies only about 9 percent of the ground water used in the basin. Although this seems to indicate underutilization of this valuable water supply, this is not necessarily the case, for many factors other than the volume of water in the aquifer affect the use of the aquifer. Such factors as climatic conditions, precipitation runoff, geology and water-yielding character of the aquifers, water-level conditions, volume of recharge and discharge, legal and economic constraints, and water-quality conditions can ultimately affect the decision to use ground water. Knowledge of the function and interaction of the various parts of this hydrologic system is important to the proper management and use of the ground-water resources of the region. The semiarid climatic conditions on the Colorado plains produce flash floods of short duration and large peak-flow rates. However, snowmelt runoff from the Rocky Mountains produces the largest volumes of water and is typically of longer duration with smaller peak-flow rates. The alluvial aquifer is recharged easily from both types of runoff and readily stores and transmits the water because it consists of relatively thin deposits of gravel, sand, and clay located in the valleys of principal streams. The bedrock aquifer is recharged less easily because of its greater thickness (as much as 3,000 feet) and prevalent layers of shale which retard the downward movement of water in the formations. Although the bedrock aquifer contains more than 50 times as much water in storage as the alluvial aquifer, it does not store and transmit water as readily as the alluvial aquifer. For example, about 91 percent of the water pumped from wells is obtained from the alluvial aquifer, yet water-level declines generally have not exceeded 40 feet. By contrast, only 9 percent of the water pumped from wells is obtained from the bedrock aquifer, yet water-level declines in this aquifer have exceeded 500 feet in some areas. Depth to water in the alluvial aquifer generally is less than 40 feet, while depth to water in the bedrock aquifer may exceed 1,000 feet in some areas. Cost of pumping water to the surface and cost of maintaining existing supplies in areas of rapidly declining water levels in the bedrock aquifer affect water use. Water use is also affected by the generally poorer quality water found in the alluvial aquifer and, to a lesser extent, by the greater susceptibility of the alluvial aquifer to pollution from surface sources. Because of these factors, the alluvial aquifer is used primarily as a source of irrigation supply, which is the largest water use in the area. The bedrock aquifer is used primarily as a source of domestic or municipal supply, which is the smaller of the two principal uses, even though the bedrock aquifer contains 50 times more stored ground water than the alluvial aquifer.

  6. CHANNEL EVOLUTION IN MODIFIED ALLUVIAL STREAMS.

    USGS Publications Warehouse

    Simon, Andrew; Hupp, Cliff R.

    1987-01-01

    This study (a) assesses the channel changes and network trends of bed level response after modifications between 1959 and 1972 of alluvial channels in western Tennessee and (b) develops a conceptual model of bank slope development to qualitatively assess bank stability and potential channel widening. A six-step, semiquantitative model of channel evolution in disturbed channels was developed by quantifying bed level trends and recognizing qualitative stages of bank slope development. Development of the bank profile is defined in terms of three dynamic and observable surfaces: (a) vertical face (70 to 90 degrees), (b) upper bank (25 to 50 degrees), and (c) slough line (20 to 25 degrees).

  7. Recurrent events on a Quaternary fault recorded in the mineralogy and micromorphology of a weathering profile, Yangsan Fault System, Korea

    Microsoft Academic Search

    Gi Young Jeong; Chang-Sik Cheong

    2005-01-01

    Recurrence characteristics of a Quaternary fault are generally investigated on the basis of field properties that are rapidly degraded by chemical weathering and erosion in warm humid climates. Here we show that in intense weathering environments, mineralogical and micromorphological investigations are valuable in paleoseismological reconstruction. A weathering profile developed in Late Quaternary marine terrace deposits along the southeastern coast of

  8. Rational regime model of alluvial channel morphology and response

    Microsoft Academic Search

    Brett C. Eaton; Michael Church; Robert G. Millar

    2004-01-01

    A theoretical model is developed for predicting equilibrium alluvial channel form. The concept of greatest relative stability, achieved by maximizing resistance to flow in the fluvial system, is presented as the basis for an optimization condition for alluvial systems. Discharge, sediment supply (quantity and calibre) and valley gradient are accepted as independent govern- ing variates. The model is used to

  9. Fertilizers mobilization in alluvial aquifer: laboratory experiments

    NASA Astrophysics Data System (ADS)

    Mastrocicco, M.; Colombani, N.; Palpacelli, S.

    2009-02-01

    In alluvial plains, intensive farming with conspicuous use of agrochemicals, can cause land pollution and groundwater contamination. In central Po River plain, paleo-channels are important links between arable lands and the underlaying aquifer, since the latter is often confined by clay sediments that act as a barrier against contaminants migration. Therefore, paleo-channels are recharge zones of particular interest that have to be protected from pollution as they are commonly used for water supply. This paper focuses on fertilizer mobilization next to a sand pit excavated in a paleo-channel near Ferrara (Italy). The problem is approached via batch test leaking and columns elution of alluvial sediments. Results from batch experiments showed fast increase in all major cations and anions, suggesting equilibrium control of dissolution reactions, limited availability of solid phases and geochemical homogeneity of samples. In column experiments, early elution and tailing of all ions breakthrough was recorded due to preferential flow paths. For sediments investigated in this study, dispersion, dilution and chemical reactions can reduce fertilizers at concentration below drinking standards in a reasonable time frame, provided fertilizer loading is halted or, at least, reduced. Thus, the definition of a corridor along paleo-channels is recommended to preserve groundwater quality.

  10. Quaternary Research Association Educational Resources

    NSDL National Science Digital Library

    The Quaternary Research Association (QRA) is an organization comprising archaeologists, botanists, civil engineers, geographers, geologists, soil scientists, zoologists and others interested in research into the problems of the Quaternary. This site describes their activities and organization. This direct link to the educational teaching resources provides access to glacier and glaciation resources.

  11. Diatom responses to late Quaternary vegetation and climate change, and to deposition of two tephras in an alpine and a sub-alpine lake in Yoho National Park, British Columbia

    Microsoft Academic Search

    Michael Hickman; Mel A. Reasoner

    1994-01-01

    The late Quaternary diatom records from alpine Opabin Lake (altitude 2285 m a.s.l.) and sub-alpine Mary Lake (altitude 2054 m a.s.l.), located in Yoho National Park, British Columbia (lat. 51 ° 21'N; long. 116 ° 20'), have been analyzed, and changes in these records have been used to reconstruct lake histories. The results have also been related to independently inferred

  12. Capturing and modelling high-complex alluvial topography with UAS-borne laser scanning

    NASA Astrophysics Data System (ADS)

    Mandlburger, Gottfried; Wieser, Martin; Pfennigbauer, Martin

    2015-04-01

    Due to fluvial activity alluvial forests are zones of highest complexity and relief energy. Alluvial forests are dominated by new and pristine channels in consequence of current and historic flood events. Apart from topographic features, the vegetation structure is typically very complex featuring, both, dense under story as well as high trees. Furthermore, deadwood and debris carried from upstream during periods of high discharge within the river channel are deposited in these areas. Therefore, precise modelling of the micro relief of alluvial forests using standard tools like Airborne Laser Scanning (ALS) is hardly feasible. Terrestrial Laser Scanning (TLS), in turn, is very time consuming for capturing larger areas as many scan positions are necessary for obtaining complete coverage due to view occlusions in the forest. In the recent past, the technological development of Unmanned Arial Systems (UAS) has reached a level that light-weight survey-grade laser scanners can be operated from these platforms. For capturing alluvial topography this could bridge the gap between ALS and TLS in terms of providing a very detailed description of the topography and the vegetation structure due to the achievable very high point density of >100 points per m2. In our contribution we demonstrate the feasibility to apply UAS-borne laser scanning for capturing and modelling the complex topography of the study area Neubacher Au, an alluvial forest at the pre-alpine River Pielach (Lower Austria). The area was captured with Riegl's VUX-1 compact time-of-flight laser scanner mounted on a RiCopter (X-8 array octocopter). The scanner features an effective scan rate of 500 kHz and was flown in 50-100 m above ground. At this flying height the laser footprint is 25-50 mm allowing mapping of very small surface details. Furthermore, online waveform processing of the backscattered laser energy enables the retrieval of multiple targets for single laser shots resulting in a dense point cloud of, both, the ground surface and the alluvial vegetation. From the acquired point cloud the following products could be derived: (i) a very high resolution Digital Terrain Model (10 cm raster), (ii) a high resolution model of the water surface of the River Pielach (especially useful for validation of topo-bathymetry LiDAR data) and (iii) a detailed description of the complex vegetation structure.

  13. Morpho-sedimentary characteristics of the Quaternary Matiali fan and associated river terraces, Jalpaiguri, India: Implications for climatic controls

    NASA Astrophysics Data System (ADS)

    Kar, Rimpal; Chakraborty, Tapan; Chakraborty, Chandan; Ghosh, Parthsarathi; Tyagi, Anil K.; Singhvi, Ashok K.

    2014-12-01

    The Matiali fan is a coarse-grained, small alluvial fan in the eastern Himalayan foothills. It co-exists side by side with the large Tista megafan and other Quaternary fluvial deposits, and has been affected by a number of young thrust faults. It is generally believed that tectonics is the main control in the deposition of these proximal fan-terrace systems. In this paper, geomorphologic and sedimentologic study of the Matiali fan and associated river terraces are combined with five OSL dates from these deposits to understand the succession of events and the forcing mechanism that shaped the geomorphology in the study area during late Quaternary time. Two aggradational terraces (T1 and T2; T2 > T1) occur within the river valleys incised on the Matiali fan. Three E-W scarps cross the fan surface, and they represent the steeper limb of the asymmetric fault-propagation folds formed over blind thrusts. These folds have deformed the fan (T3) and T2 terrace sediments, but the youngest T1 terrace deposits have remained undeformed. Sedimentological studies indicate continuous gradation from the coarsening-upwards mass-flow megagravel in the proximal part to the traction transported finer sheetflood gravels in the distal part, implying a continuous sedimentation history across the fan, uninterrupted by any evidence of syn-depositional tectonic movement. Poorly consolidated sandy gravels of the terraces indicate deposition through braided fluvial processes during a later period of sediment aggradation that filled up the incised river valleys. Previously published 14C dates indicate that deposition of the Matiali fan started around 34 ka coinciding with a period of the intensified Indian summer monsoon of MIS-3. It is suggested that the fan was abandoned and river valleys incised during the LGM between 24 and 18 ka when the discharge decreased substantially. Increased rainfall and sediment supply, with their inherent fluctuations, during wetter periods of MIS-2 and MIS-1 since 12 ka probably resulted in the aggradation of T2 and T1 as shown by our OSL dates. OSL dates from the top of deformed T2 and base of undeformed T1 indicate that the Chalsa fold formed between ~ 11 and ~ 6 ka. Succession of geomorphic and deformational events reconstructed from this study and available age data indicate that the Matiali fan and terrace aggradation coincides with periods of increased monsoonal precipitation, whereas tectonic movements along blind thrusts of Chalsa and Matiali took place later, deforming the fan and older terrace deposits. The evidence unequivocally indicates, contrary to the prevalent notion of tectonic control of geomorphic features in the proximal mountain-front setting, that the deposition of the fan-terrace system was primarily controlled by the fluctuation of the Asian summer monsoon rather than Himalayan tectonics.

  14. Historical Ground-Water Development in the Salinas Alluvial Fan Area, Salinas, Puerto Rico, 1900-2005

    USGS Publications Warehouse

    Rodriguez, Jose M.; Gómez-Gómez, Fernando

    2008-01-01

    The Salinas alluvial fan area has historically been one of the most intensively used agricultural areas in the South Coastal Plain of Puerto Rico. Changes in agricultural practices and land use in the Salinas alluvial fan have also caused changes in the geographic distribution of ground-water withdrawals from the alluvial aquifer. As a result, the ground-water balance and ground-water flow pattern have changed throughout the years and may explain the presence of saline ground water along parts of the coast at present. By providing a reconstruction of historical ground-water development in the Salinas alluvial fan area, from the initial years of aquifer development at about 1900 to the most recent conditions existing in 2005, water resources managers and planners can use the results of the analysis for a more complete understanding of aquifer conditions especially pertaining to water quality. This study effort was conducted by the U.S. Geological Survey in cooperation with the Puerto Rico Department of Natural and Environmental Resources as a contribution in the management of the Jobos Bay National Estuarine Research Reserve. The study area encompasses about 20 mi2 (square miles) of the extensive South Coastal Plain alluvial aquifer system (fig. 1). The study area is bounded to the north by foothills of the Cordillera Central mountain chain, to the south by the Caribbean Sea, and to the east and west by the Rio Nigua de Salinas and the Quebrada Aguas Verdes, respectively. Fan-delta and alluvial deposits contain the principal aquifers in the study area.

  15. Abo Formation alluvial facies and Associated Basin Fill, Sacramento Mountains, New Mexico

    SciTech Connect

    Speer, S.W.

    1986-03-01

    Outcrops of the Abo Formation (Wolfcampian to early Leonardian age) in the Sacramento Mountains of south-central New Mexico record the evolution of a dry alluvial fan system as it was deposited off the pedernal uplift into the Orogrande basin. The location and orientation of present-day outcrops allow us to observe an inferred east-to-west transverse facies tract consisting of: (1) proximal alluvial fans (lower Abo), which are contiguous in places with underlying Laborcita Formation fan-deltaic sediments; (2) medial anastomosed streams (middle Abo); and (3) distal low-gradient mud-dominated flood basins characterized by either distributary streams (upper Abo) or clastic tidal flats (Lee Ranch Tongue of the Abo) with associated marine carbonates (Pendejo Tongue of the Hueco Formation). Tectonism in the Pedernal highlands, which climaxed during the Late Pennsylvanian, apparently continued well into the Wolfcampian in this region, as evidenced by a major basal Abo unconformity and distinct stacked megasequences of lower Abo alluvial fan lithofacies. However, by the middle Abo, tectonic activity had quiesced and the uplift began eroding and retreating to the north and east. By the late Abo, a pediment surface had formed that was subsequently onlapped by upper Abo and eventually Yeso Formation sediments.

  16. Large Well-exposed Alluvial Fans in Deep Late-Noachian Craters

    NASA Technical Reports Server (NTRS)

    Moore, J. M.; Howard, A.D.

    2004-01-01

    Large, fresh-appearing alluvial fans (typically greater than 10 km long) have been identified during a systematic search of 100 m/pixel low-sun daylight THEMIS IR imaging in deep late-Noachian or early- Hesperian craters. Our study of these fans was augmented with MOLA-derived topography and high-resolution MOC and THEMIS VIS images where available. The influence of alluvial fan deposition on the topography of crater floors has been recognized in previous topographic studies. Recent Mars Odyssey-era studies have also identified and described in detail a fluvial delta or fan of approximately the same age as the alluvial fans of this study. Our results, at the time of this writing, indicate that these fans are only found in less than 5% of all craters = 70 km in diameter within a large study region. In every case the fan-containing craters were restricted to a latitude belt between 20 deg S and 30 deg S. All of which had significant topographic relief and appeared morphologically younger than typical mid-Noachian craters in the size range. However, large fans were not found in the most pristine (and presumably youngest) craters in this size range. Most Martian fans have morphologies consistent with terrestrial debris-flow-dominated fans.

  17. Large Well-Exposed Alluvial Fans in Deep Late-Noachian Craters

    NASA Technical Reports Server (NTRS)

    Moore, J. M.; Howard, A. D.

    2004-01-01

    Large, fresh-appearing alluvial fans (typically greater than 10 km long) have been identified during a systematic search of 100 m/pixel low-sun daylight THEMIS IR imaging in deep late-Noachian or early-Hesperian craters. Our study of these fans was augmented with MOLA-derived topography and high-resolution MOC and THEMIS VIS images where available. The influence of alluvial fan deposition on the topography of crater floors has been recognized in previous topographic studies. Recent Mars Odyssey-era studies have also identified and described in detail a fluvial delta or fan of approximately the same age as the alluvial fans of this study. Our results, at the time of this writing, indicate that these fans are only found in less than 5% of all craters greater than or equal to 70 kilometers in diameter within a large study region. In every case the fan-containing craters were restricted to a latitude belt between 20 degrees S and 30 degrees S. All of which had significant topographic relief and appeared morphologically younger than typical mid-Noachian craters in the size range. However, large fans were not found in the most pristine (and presumably youngest) craters in this size range. Most Martian fans have morphologies consistent with terrestrial debris-flow-dominated fans.

  18. Late-Quaternary paleoenvironmental evolution of Lesina lagoon (southern Italy) from subsurface data

    NASA Astrophysics Data System (ADS)

    Ricci Lucchi, Marianna; Fiorini, Flavia; Luisa Colalongo, Maria; Vittorio Curzi, Pietro

    2006-01-01

    Integrated sedimentological and micropaleontological (foraminifers and ostracods) analyses of two 55 m long borehole cores (S3 and S4) drilled in the subsurface of Lesina lagoon (Gargano promontory—Italy) has yielded a facies distribution characteristic of alluvial, coastal and shallow-marine sediments. Stratigraphic correlation between the two cores, based on strong similarity in facies distribution and AMS radiocarbon dates, indicates a Late Pleistocene to Holocene age of the sedimentary succession. Two main depositional sequences were deposited during the last 60-ky. These sequences display poor preservation of lowstand deposits and record two major transgressive pulses and subsequent sea-level highstands. The older sequence, unconformably overlying a pedogenized alluvial unit, consists of paralic and marine units (dated by AMS radiocarbon at about 45-50,000 years BP) that represent the landward migration of a barrier-lagoon system. These units are separated by a ravinement surface (RS1). Above these tansgressive deposits, highstand deposition is characterised by progradation of the coastal sediments. The younger sequence, overlying an unconformity of tectonic origin, is a 10 m-thick sedimentary body, consisting of fluvial channel sediments overlain by transgressive-regressive deposits of Holocene age. A ravinement surface (RS2), truncating the transgressive (lagoonal and back-barrier) deposits in core S4, indicates shoreface retreat and landward migration of the barrier/lagoon system. The overlying beach, lagoon and alluvial deposits are the result of mid-Holocene highstand sedimentation and coastal progradation.

  19. Characterization of dust emission from alluvial sediments using aircraft observations and modeling

    NASA Astrophysics Data System (ADS)

    Schepanski, K.; Flamant, C.; Chaboureau, J.; Kocha, C.; Banks, J.; Brindley, H. E.; Lavaysse, C.; Marnas, F.; Pelon, J.; Tulet, P.

    2013-12-01

    Recent studies using satellite observations show that numerous dust sources are located in the foothills of arid and semi-arid mountain regions such as over North Africa. Alluvial sediments deposited on the valley bottoms and flood plains are very prone to wind erosion and frequently serve as dust source. High surface wind speeds related to the break-down of the nocturnal low-level jet (LLJ) during the morning hours are identified as a frequent driving mechanism for dust uplift. We investigate dust emission from alluvial dust sources located within the upland region in northern Mauritania and discuss the impact of valleys with regard to their role as dust source. Measures for local atmospheric dust burden were retrieved from airborne observations, MSG SEVIR dust AOD fields and MesoNH model simulations, and analyzed in order to provide complementary information on dust source activation and local dust transport at different horizontal scales. Vertical distribution of atmospheric mineral dust was obtained from the LNG backscatter lidar system flying aboard the French Falcon-20 aircraft. Lidar extinction coefficients were compared to topography, aerial photographs, and dust AOD fields to confirm the relevance of alluvial sediments at the valley bottoms as dust source. The observed dust emission event was further evaluated using the regional model MesoNH. A sensitivity study on the impact of the horizontal grid spacing highlights the importance of the spatial resolution on simulated dust loadings. The results further illustrate the importance of an explicit representation of alluvial dust sources in such models to better capture the spatial-temporal distribution of airborne dust concentrations.

  20. Fire, climate, and alluvial system dynamics: A Holocene record from Yellowstone National Park

    SciTech Connect

    Meyer, G.A. (Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Geology); Wells, S.G. (Univ. of California, Riverside, CA (United States). Dept. of Earth Sciences); Jull, A.J. (Univ. of Arizona, Tucson, AZ (United States). NSF-Arizona Accelerator Facility For Isotope Dating)

    1992-01-01

    Many large debris-flow, hyperconcentrated-flow, and flood-streamflow sediment transport events have been produced in steep basins that were burned in the 1988 fires in northeaster Yellowstone National Park. The charcoal- and fines-rich character of fire-related debris-flow deposits and the abundance of similar facies in Holocene fan sections have allowed them to construct a [sup 14]C-dated chronology of fire-related sedimentation in the Soda Butte and Slough Creek drainages for the last 3500 years. Major periods of fire-related alluvial fan aggradation are interpreted as drought-dominated with the support of local paleoenvironmental data and statistical analyses of historical climate-fire relations; however, some fire-related events may occur due to high climatic variability and severe short-term drought within generally moist intervals. The last major episode of fire-related debris-flow activity encompasses the Medieval Warm Period of 900--1300 AD and peaks ca. 1150 AD; a prior episode culminates ca. 350--100 BC. Wetter periods contain minimal fire-related fan sedimentation; however, floodplain broadening and aggradation occurs along axial streams. Higher average snowmelt runoff discharges are probably involved, such that the dominant alluvial activity shifts to removal of sediment from alluvial fan storage and transport to downstream floodplains. The Little Ice Age (ca. 1300--1900 AD) contains minimal fire-related debris0flow activity and is associated with floodplain aggradation of the T4 terrace, and independent evidence suggests substantially wetter conditions during T3 aggradation ca. 350--650 AD. Thus, small-scale climate changes of the late Holocene effectively control the dominant mode of alluvial activity.

  1. Characterization of alluvial aquifers by multiscale hydrostratigraphic interpretation of DC resistivity data

    NASA Astrophysics Data System (ADS)

    Mele, Mauro; Bersezio, Riccardo; Giudici, Mauro

    2010-05-01

    The characterization of aquifer heterogeneity plays a key role for the 3-D modelling of conductivity (K) distribution in the subsurface of alluvial plains. DC methods such as Vertical Electrical Soundings (VES) and Electrical Resistivity Ground Imaging (ERGI) yield respectively the 1-D and 2-D resistivity (?) distribution in the ground and are often applied in hydrogeology because ? is controlled by the prevailing process of current conduction ('shale' vs. electrolytic conduction) determined by the occurrence of fine-grained sediments and saline groundwater. Assuming that the sedimentary heterogeneity can be described with hierarchical elements at different scales (from hydrofacies to hydrostratigraphic systems) and recalling that the resolution of DC surveys decreases with depth, we propose an interpretation of the subsurface ? distribution as a function of the hierarchical properties of aquifers (i.e., the vertical trends of facies with prevailing 'shale' or electrolytic conduction) with hydrostratigraphic constrains. A correlation between ? and pore-fluid saturation and chemistry permits the use of resistivity as a 'proxy' of facies stacking. Our case-study is the Quaternary valley of palaeo-Sillaro extinct meandering river (Po plain, Italy). The local stratigraphy up to 80 m below ground surface consists of LGM sand-gravel point bar and channel bodies overlying: i) clay to fine sand aquitard of an Upper Pleistocene flood plain, ii) alternating gravel-sand aquifer bodies and fine sand to silty-clay drapes formed by Middle-Upper Pleistocene braiding to meandering depositional systems that developed above iii) a basal aquiclude of silty-clays. To interpret 1-D resistivity models obtained by 89 VES collected with Schlumberger array (maximum half-spacing 300 m) over an area of 30 km2, a Coarse-to-Fine (C/F) litho-textural ratio (particle size cut-off=0.30 mm) was used to classify hydrofacies. The variability of C/F was compared with the K and ? values of hydrofacies, both in the unsaturated and the saturated zone. A local relationship between K and ? was then established and used to identify i) a fine litho-textural association (C/F1), with a prevailing electrolytic conduction, high ? and high K. The electrical resistivity was then reclassified in terms of the prevailing hydraulic behaviour (low or high K units), taking into account the differences between the saturated and unsaturated zones. A representation of the sedimentary heterogeneity and connectivity was obtained through the correlation of VES models by vertical polarity of electrical contrasts and lateral persistence of ? values which led us to map geoelectrical bodies informally named electrostratigraphic units (EsUs). The EsUs are defined by horizontal variations of the vertical electrostratigraphic sequence and characterized by a thickness coherent with the principles of electrical equivalence and suppression. 3000 m of 2-D ERGI sections collected with Wenner-Schlumberger array (electrodes spacing 5 m) led us to a further characterization of the EsUs at metric scale up to 40 m b.g.s.. Shallow EsUs represent vertical variations of ? related to the litho-textural contrasts at the scale of the hydrofacies, as a function of the proportion between fine and coarse textures within each sedimentary facies (C/F ratio). Deeper EsUs represent vertical variations ? related to the litho-textural contrasts within an heterogeneous and hierarchically stratified medium at the hydrostratigraphic systems scale.

  2. Late Pleistocene coastal loess deposits of the central west coast of North America: Terrestrial facies indicators for marine low-stand intervals

    NASA Astrophysics Data System (ADS)

    Peterson, Curt D.; Grathoff, Georg H.; Reckendorf, Frank; Percy, David; Price, David M.

    2014-03-01

    Coastal loess deposits measured in sea cliffs, bay cliffs, road cuts and boreholes (62 sites) are compiled for the states of Washington, Oregon, and California in the central west coast of North America (1700 km in length). The loess-enriched deposits are recognized by (1) substantial abundances of silt (30-90% by weight) and (2) depositional settings in uplifted marine terraces or dune fields that are situated well above alluvial floodplains at the coast. Total loess thickness above the MIS5a marine terrace, or 80 ± 20 ka basal TL age, ranges from 0.1 to 8.0 m in 46 dated sites. Loess deposits reach maximum thickness (5-8 m) in the vicinities of glacial outwash plains in the highest latitudes. Loess thickness in the middle and lower latitudes increases with proximity to 1) large river mouths (>3 × 106 mt yr-1 modern suspended sediment discharge) and 2) broad shelf widths (>10 km distance from 0 to -100 m depth). Coastal loess deposits dated by TL or radiocarbon (37 samples) range from ˜250 to 11 ka in age, but generally fall into the MIS4-2 marine low-stand intervals (32 dates between 77-15 ka). The coastal loess facies represent marine low-stand intervals in coastal Quaternary sequences from the central west coast of North America.

  3. Numerical Simulation of Sediment Plug Formation in Alluvial Channels

    NASA Astrophysics Data System (ADS)

    Posner, A. J.; Duan, J. G.

    2011-12-01

    A sediment plug is the aggregation of sediment in a river reach that completely blocks the original channel resulting in plug growth upstream by accretion and flooding in surrounding areas. Sediment plugs historically form over relatively short periods, in many cases a matter of weeks. Although sediment plugs are much more common in reach constrictions associated with large woody debris, the mouths of tributaries, and along coastal regions, this investigation focuses on sediment plug formation in an alluvial river. During high flows in the years 1991, 1995, 2005, and 2008, a sediment plug formed in the San Marcial reach of the Middle Rio Grande. The Bureau of Reclamation has had to spend millions of dollars dredging the channel to restore flows to Elephant Butte Reservoir. The hydrodynamic and sediment transport processes, associated with plug formation, occurring in this reach are driven by 1) a flow constriction associated with a rock outcrop, 2) a railroad bridge, and 3) the water level of the downstream reservoir. The three-dimensional hydrodynamic model, Delft3D, was implemented to determine the hydrodynamic and sediment transport parameters and variables required to simulate plug formation in an effort to identify hydro- and morphodynamic thresholds. Several variables were identified by previous studies as metrics for plug formation. These variables were used in our investigation to detect the relative magnitude of each process. Both duration and degree of high flow events were simulated, along with extent of cohesive sediment deposits, reservoir level, and percent of fines in suspended sediment distribution. Results of this analysis illustrate that this model is able to reproduce the sediment plug formation. Model calibration was based on measured water levels and changes in bathymetry using both sediment transport and morphologic change parameters. Changes to hydraulic and sediment parameters are not proportional to morphologic changes and are asymptotic in their response. These results suggest that there are thresholds to predict plug formation and that the contribution of specific variables to plug formation is not uniform. Sediment plug formation is a costly and dangerous phenomenon, especially in large alluvial rivers. This investigation yielded specific insights into the hydrodynamic and morphologic processes occurring during sediment plug formation. These insights can be used to reduce the risk of plug formation and predict the locations and times of other sediment plugs.

  4. Particle dynamics: The continuum of bedrock to alluvial river segments

    NASA Astrophysics Data System (ADS)

    Wohl, Ellen

    2015-07-01

    Particle dynamics refers to production, erosion, transport, and storage of particulate material including mineral sediment and organic matter. Particle dynamics differ significantly between the end members of bedrock and alluvial river segments and between alluvial river segments with different grain-size distributions. Bedrock segments are supply limited and resistant to change, with relatively slow, linear adjustments and predominantly erosion and transport. Particle dynamics in alluvial segments, in contrast, are transport limited and dominated by storage of mineral sediment and production of organic matter. Alluvial segments are resilient to change, with relatively rapid, multidirectional adjustments and stronger internal influences because of feedbacks between particles and biota. Bedrock segments are the governors of erosion within a river network, whereas alluvial segments are the biogeochemical reactors. Fundamental research questions for both types of river segments center on particle dynamics, which limit network-scale incision in response to base level fall (bedrock segments) and habitat, biogeochemical reactions, and biomass production (alluvial segments). These characterizations illuminate how the spatial arrangement of bedrock and alluvial segments within a river network influence network-scale resistance and resilience to external changes in relative base level, climate, and human activities.

  5. Estimating alluvial fan surface ages using Landsat 8 multispectral imagery

    NASA Astrophysics Data System (ADS)

    D'Arcy, Mitch; Mason, Philippa J.; Whittaker, Alexander C.; Roda Boluda, Duna C.

    2015-04-01

    Accurate exposure age models are now essential for geomorphological and stratigraphic field research, and generally depend on laboratory analyses such as radiocarbon, cosmogenic nuclide or luminescence approaches. However, these techniques cannot be deployed in situ in the field, meaning other methods are needed to produce a preliminary age model, map depositional surfaces of different ages, and select sampling sites for the types of laboratory analyses outlined above. With the widespread availability of high-resolution multispectral imagery, a promising approach is to use remotely sensed data to discriminate depositional surfaces with different ages. Here, we use new Landsat 8 Operational Land Imager (OLI) multispectral imagery to characterise the reflectance of 35 alluvial fan surfaces in the semi-arid Owens Valley, California. These surfaces have been mapped in detail in the field, have similar granitic compositions, and have well-constrained exposure ages ranging from modern to ~ 125 ka, measured using a high density of 10-Be cosmogenic nuclide samples. We identify a clear age signal recorded in the spectral properties of these surfaces. With increasing exposure age, there is a predictable redshift effect in the reflectance of the surfaces across the visible and short-wave infrared spectrum. Simple calculations, such as the brightness ratio of red/blue wavelengths, produce sensitive power law relationships with exposure age for at least 125 ka, meaning Landsat 8 imagery can be used to estimate surface exposure age remotely, at least in this calibrated dryland location. The ability to remotely sense exposure age has useful implications for field mapping, selecting suitable sampling sites for laboratory-based exposure age techniques, and correlating existing age constraints to previously un-sampled surfaces. We present the uncertainties associated with this spectral approach to exposure dating, evaluate its likely physical origins, and discuss its applicability in other locations and with other remotely sensed datasets.

  6. Quaternary GIS Laboratory

    NSDL National Science Digital Library

    This is the home page of the Quaternary Geographic Information System (GIS) Laboratory at the Institute of Arctic and Alpine Research (INSTAAR) at the University of Colorado. The laboratory supports quantitative spatial analysis of glacier, climate, coastal, and other environmental relationships at high latitudes. Users can access a collection of climate animations for the State of Alaska which show seasonal variation in monthly temperature and precipitation. There is also a set of high-resolution imagery and terrain models for Barrow, Alaska, an animation of the land bridge between Asia and North America, an atlas of paleoglaciation for the state, and links to a variety of other projects involving climatology, paleoclimatology, and glacial geomorphology in the Sate of Alaska.

  7. Empirical assessment of theory for bankfull characteristics of alluvial channels

    NASA Astrophysics Data System (ADS)

    Trampush, S. M.; Huzurbazar, S.; McElroy, B.

    2014-12-01

    We compiled a data set of 541 bankfull measurements of alluvial rivers (see supporting information) and used Bayesian linear regression to examine empirical and theoretical support for the hypothesis that alluvial channels adjust to a predictable condition of basal shear stress as a function of sediment transport mode. An empirical closure based on channel slope, bankfull channel depth, and median grain size is proposed and results in the scaling of bankfull Shields stress with the inverse square root of particle Reynolds number. The empirical relationship is sufficient for purposes of quantifying paleohydraulic conditions in ancient alluvial channels. However, it is not currently appropriate for application to alluvial channels on extraterrestrial bodies because it depends on constant-valued, Earth-based coefficients.

  8. Kinematic wave model of bed profiles in alluvial channels 

    E-print Network

    Tayfur, Gokmen; Singh, Vijay P.

    2006-06-21

    A mathematical model, based on the kinematic wave (KW) theory, is developed for describing the evolution and movement of bed profiles in alluvial channels. The model employs a functional relation between sediment transport rate and concentration, a...

  9. INTRODUCTION Mesopotamia is the broad, flat alluvial plain

    E-print Network

    deMenocal, Peter B.

    INTRODUCTION Mesopotamia is the broad, flat alluvial plain between the Tigris and Euphrates Rivers to the headwaters of the Tigris and Euphrates Rivers from ca. 4300 to 4200 B.P. Particularly important

  10. The Shape of Trail Canyon Alluvial Fan, Death Valley

    NASA Technical Reports Server (NTRS)

    Farr, Tom G.; Dohrenwend, John C.

    1993-01-01

    A modified conic equation has been fit to high-resolution digital topographic data for Trail Canyon alluvial fan in Death Valley, California. Fits were accomplished for 3 individual fan units of different age.

  11. Age and origin of the Gezira alluvial fan between the Blue and White Nile rivers

    NASA Astrophysics Data System (ADS)

    Williams, martin

    2014-05-01

    The Gezira is a low-angle alluvial fan bounded by the Blue Nile to the east and the White Nile to the west. It is the main agricultural region of Sudan and produces high quality long-staple cotton for export. Dark cracking clays (vertisols) cover much of the Gezira and range in age from 50 kyr to Holocene. The Gezira is traversed by a series of defunct sandy channels that originate between Sennar and Wad Medani on the present-day Blue Nile. With a radius of 300 km and an area of 40,000 km2 the Gezira is a mega-fan. The younger channels range in age from early Holocene to 100 kyr, while near surface channels filled with rolled quartz and carbonate gravels have ages back to >250 kyr. Boreholes in the Gezira reveal coarse alluvial sands and gravels in now buried channels overlain by alluvial clays, forming a repetitive sequence of fining-upwards alluvial units. that probably extend back to Pliocene times. The fan is up to 180 m thick with a volume of ~1,800 km3. The sandy or gravelly bed-load channels coincide with colder drier climates and sparse vegetation in the Ethiopian headwaters of the Blue Nile and the alluvial clays denote widespread flooding during times of stronger summer monsoon. The early stages of such flood events were often accompanied by mass burial of Nile oyster (Etheria elliptica) beds, such as the 45-50 kyr floods that deposited up to 5 m of clay in the northern Gezira. A unique feature of the eastern Gezira is a former Blue Nile channel at least 80 km long running parallel to the present river and entirely filled with volcanic ash. The channel was only 3-4 m deep and 20-30 m wide. Very fine laminations and cross-beds, together with locally abundant phytoliths and sponge spicules, suggest slow-moving water, with flow dispersed across many distributary channels. The ash geochemistry is similar to that in the lower part of the Kibish Formation in the lower Omo valley of southern Ethiopia and points to a minimum age of 100 kyr and a maximum age of 190 kyr. The Ethiopian volcano that provided the ash was located on the interfluve between the upper Omo and the upper Blue Nile. Although the Blue Nile has frequently changed course in the last 250 kyr, it has flowed close to its present channel at least three times in that time.

  12. The role of tropical cyclones on landscape dynamics in southern Baja California, Mexico based on Late Pleistocene-Holocene alluvial stratigraphy

    NASA Astrophysics Data System (ADS)

    McDonald, Eric; Antinao, Jose Luis; Rhodes, Edward J.; Brown, Nathan; Gosse, John

    2015-04-01

    Region-wide alluvial records provide evidence that time-transgressive changes in climate can be a major driver of landscape evolution. Historically, landfall of eastern Pacific tropical cyclones in southwestern North America during the late summer and early fall provide the strongest storms that have demonstrated geomorphic impact on the landscape. The alluvial fan record of the southern portion of Baja California (Mexico) was investigated to determine if linkages exist between region-wide fluvial deposits and tropical cyclones. The regional distribution and Pleistocene to Holocene morphostratigraphy of alluvial fans has been established for the southern portion of Baja California with primary focus on the La Paz and San José del Cabo basins. Six discrete morphopedosedimentary alluvial units (Qt1 through Qt6) were differentiated across the region using a combination of geomorphologic mapping, sedimentological analysis, and soil development further reinforced with geochronology using radiocarbon, optically stimulated luminescence and cosmogenic depth-profiles. A first phase of regional aggradation began before ~ 100 ka (Qt1) and culminated ~10 ka (Qt4). After deposition of Qt4, increasing regional incision of older units and the progressive development of a channelized alluvial landscape coincide with deposition of Qt5 and Qt6 units in a second, incisional phase. All units are conformed of multiple 1-3 m thick alluvial packages deposited in upper-flow regime and representing individual storms. Aggradational units (Qt1-Qt4) covered broad (>2 km) channels in the form of sheetflood deposition while incisional stage deposits are mostly confined to channels of ~0.5-2 km width. Continuous deposition of the thicker sequences is demonstrated by closely spaced luminescence dates in vertical profiles. In a few places disconformities between major units are evident and indicated by partly eroded buried soils. Analysis of historical terraces as part of the younger units incised into older fans show that deposition was accomplished by large tropical cyclone events. Older units feature the same sedimentological traits as these historical deposits. We interpret the whole sequence as indicating discrete periods during the Late Pleistocene and Holocene when climatic conditions allowed large tropical cyclone events that today are not expressed. These discrete periods can be associated with specific periods when (a) insolation at the Equator was at peaks determined by precessional cycles and (b) the Tropical Pacific might have shown a state similar to that currently displayed during El Niño events.

  13. Radar facies and architecture of alluvial fans and related sediments in high-energy alpine environments, British Columbia

    NASA Astrophysics Data System (ADS)

    Ekes, Csaba

    2000-08-01

    It is widely recognized that the dominant depositional processes on alluvial fans include rock falls, rock slides, rock avalanches, debris flows, sheetfloods and incised-channel floods. A fundamental question addressed in this thesis is: Can ground penetrating radar (GPR) differentiate between the sediments associated with these processes? Do these individual deposits have characteristic radar reflection signatures? The dissertation is divided into two parts. In part one, a calibration exercise conducted in southern British Columbia, it was demonstrated that GPR was able to obtain good penetration and resolution in rock fall, rock slide, fluvial and alluvial fan sediments, and that a characteristic radar reflection pattern (or radar facies) can be assigned to these deposits. Bedrock reflection pattern is characterised by a discontinuous radar signal and by stacked diffractions. The radar facies for rock slide and rock avalanche sediments, where boulders constitute the predominant clast size, is characterized by discontinuous, high amplitude, macro-scale, hyperbolic reflections that are different from diffractions generated by bedrock. Alluvial fans dominated by debris flow processes produce a chaotic and discontinuous radar pattern; diffractions in these patterns are attributed to boulders. Alluvial fans dominated by sheetflood processes are likely to produce surface-parallel, gently dipping, more or less continuous radar patterns. Large-scale meandering-river radar-patterns are characterized by high amplitude, continuous, dipping clinoforms. Braided-river radar facies, based on data collected on the Kicking Horse braidplain, are characterized by predominantly horizontally continuous reflections with few identifiable features. Based solely on GPR data, it was possible to distinguish between sediments of meandering and braided rivers. Analysis of over 95 km GPR data suggests that alluvial fan radar-reflection patterns are distinctly different from those observed in other environments, including those from gravel-bed rivers. None of the radar patterns observed in river channel environments were found on any of the alluvial fans surveyed. The objective of the second part of the thesis is the analysis of the large-scale, three dimensional internal architecture and depositional history of Cheekye Fan in southwestern British Columbia. The fan receives sediments from debris flows which represent a hazard for transportation and residential development on its surface. GPR proved to be an efficient technique for analysing the large-scale internal architecture of Cheekye Fan. Fan sediments overlie till and undulating bedrock in the northern and eastern fan sector. Two architectural components were defined: subaqueously-deposited fan-delta sediments and subaerial alluvial-fan sediments. Fan sediments were tentatively further divided into: (a) matrix-rich diamicton that appears predominant at the core of the fan and at lower stratigraphic horizons, suggesting bouldery rock-slide or debris flow origin, and (b) horizontally-bedded sheetflood sand and gravel dominating the upper 20--25 m of the stratigraphic column. Based on GPR data, radiocarbon dating and test-pit information, the post-glacial depositional history and evolution of Cheekye Fan is as follows. It is estimated that 90% of fan volume was deposited prior to 6000 years BP. Sediment availability declined after ca. 6000 yr. BP and fan growth slowed towards equilibrium. Although the last major debris flow which reached lower Cheekye Fan surface occurred at about 1300 yr. BP, Cheekye Fan is essentially a paraglacial fan, largely a product of the geological past. This fact should be taken into consideration when making future hazard estimates. Based on subsurface information there is little similarity between the early and late Holocene rates of deposition.

  14. Geomorphologic flood-hazard assessment of alluvial fans and piedmonts

    USGS Publications Warehouse

    Field, J.J.; Pearthree, P.A.

    1997-01-01

    Geomorphologic studies are an excellent means of flood-hazard assessment on alluvial fans and piedmonts in the southwestern United States. Inactive, flood-free, alluvial fans display well developed soils, desert pavement, rock varnish, and tributary drainage networks. These areas are easily distinguished from flood-prone active alluvial fans on aerial photographs and in the field. The distribution of flood-prone areas associated with alluvial fans is strongly controlled by fanhead trenches dissecting the surface. Where fanhead trenches are permanent features cut in response to long-term conditions such as tectonic quiescence, flood-prone surfaces are situated down-slope from the mountain front and their positions are stable for thousands of years. Since the length and permanency of fanhead trenches can vary greatly between adjacent drainages, it is not appropriate to use regional generalizations to evaluate the distribution and stability of flood-hazard zones. Site-specific geomorphologic studies must be carried out if piedmont areas with a high risk of flooding are to be correctly identified and losses due to alluvial-fan flooding minimized. To meet the growing demand for trained professionals to complete geomorphologic maps of desert piedmonts, undergraduate and graduate geomorphology courses should adopt an instructional unit on alluvial-fan flood hazards that includes: 1) a review of geomorphologic characteristics that vary with surface age; 2) a basic mapping exercise; and 3) a discussion of the causes of fanhead trenching.

  15. Depositional and pedogenic influences on the environmental geology of Holocene Mississippi River floodplain deposits near Ferriday, Louisiana

    Microsoft Academic Search

    Andres Aslan; Whitney J. Autin

    1996-01-01

    Core descriptions and the mineralogy of Holocene Mississippi River floodplain deposits in Louisiana provide insights on fluid migration pathways and the origin of iron-rich ground waters in the Mississippi River Alluvial Aquifer (MRAA). Vertical changes in the sedimentologic and pedologic characteristics of floodplain deposits near Ferriday, Louisiana, provide evidence for two stages of floodplain development and suggest that depositional processes

  16. Effects of weathering and lithology on the quality of aggregates in the alluvial fans of Northeast Rivand, Sabzevar, Iran

    NASA Astrophysics Data System (ADS)

    Bahrami, Shahram; Fatemi Aghda, Seyed Mahmoud; Bahrami, Kazem; Motamedi Rad, Mohammad; Poorhashemi, Sima

    2015-07-01

    Alluvial fans as depositional landforms can be considered as potential sources of aggregates. As the age of alluvial fans increases, their constituent sediments are exposed to longer periods of weathering and increased mineral alteration, resulting in a decrease in aggregate quality. In this study, physical properties and point load tests were used to assess the aggregate quality on three alluvial fan surfaces (relict, old and young) in the northeastern part of Rivand village in west of Sabzevar, Northeast Iran. Differentiating young from old and relict fans was carried out based on geomorphic criteria such as weathering features, fan surface morphology and drainage pattern. The young alluvial fan is characterized by sub-rounded and unvarnished clasts, distributary drainage patterns and a relatively flat surface, whereas old and relict fans are characterized by incised and rough surfaces, tributary drainage pattern and highly weathered and varnished clasts due to their long-term exposure to weathering. Due to a range of rock types occurring across each fan surface, lithological studies were performed to eliminate the effect of lithology on aggregate quality. A total of 18 rock types comprising comparable lithologies were sampled from each of the three alluvial fans. Results show that, in almost all 18 rock types, the point load test values increases from relict to young fans whereas porosity and percentage of water absorption decrease, implying that aggregate quality decreases with time as a function of duration of exposure to weathering. Also, the strength of aggregates in all three fans decreases from the fan apex to the fan toe. Data show that micaceous, intrusive igneous rocks, tuffs with high porosity and fine-grained extrusive igneous rocks with some porosity are more sensitive to physical weathering, and therefore have lower strength, particularly on the relict and old fans. Overall, variations in aggregate strength on these fans can be attributed to the relative ages of fans, with relict and old fans containing lower quality aggregates due to the longer-term exposure to weathering.

  17. Modern alluvial fan and deltaic sedimentation in a foreland tectonic setting: the Lower Mesopotamian Plain and the Arabian Gulf

    NASA Astrophysics Data System (ADS)

    Baltzer, Frédéric; Purser, Bruce H.

    1990-05-01

    The Arabo-Persian Gulf, generally considered as a classical carbonate basin, in fact also includes important terrigenous systems whose nature and geometry are related closely to the tectonic framework. The Gulf is bordered along its northeastern periphery by an active alpine system which constitutes a major source of both siliceous and calcareous detritus. There are four types of terrigenous discharge which are classified according to their structural relationships. Numerous alluvial fans terminate ephemeral consequent streams draining the flanks of anticlines forming the external parts of the Zagros Mountain belt. Alluvial-fan deltas studied in detail in southeastern Iran terminate semi-permanent streams which flow along major synclinal axis. They are composed mainly of fine carbonate detritus, part of which accumulates as spectacular marine mud banks. Two major types of delta occur. Relatively small marine deltas, associated with permanent antecedent streams which cross the Zagros fold system, are scattered along the Persian shoreline. The other is the a major deltaic complex which is associated with the Tigris-Euphrates Rivers. This system has prograded along the main axis of the Gulf, the resulting Mesopotamian Plain filling at least half of the original basin which, in early Quaternary times, extended from Hormuz to Syria.

  18. Lower Mississippi River: A Mixed Bedrock-alluvial Channel

    NASA Astrophysics Data System (ADS)

    Nittrouer, J. A.; Mohrig, D.; Allison, M. A.

    2007-12-01

    High-resolution multibeam bathymetric and CHIRP sub-bottom seismic data from the lower most 110 km of the Mississippi River offer a detailed depiction of the bed surface, revealing portions of the channel covered by sediment and areas of exposed substrate. A single line data swath running from Head of Passes to the English Turn bend was collected during low water discharge conditions. The swath zigzags up the river channel, intersecting each bank at an oblique angle of roughly 45 degrees, thereby ensuring that the entire channel bottom is adequately represented by the survey. Local composition of the channel bed is determined based on distinctive bathymetric characteristics, and is corroborated by grab samples collected along the survey path. Dune fields, composed of active and inactive dunes, cover 77% of the channel bottom and are most abundant in straight reach segments. Stagnant dunes, mantled by high-porosity ephemeral mud, cover 7% of the channel bed and tend to be located in shallower water near the river banks (10-15 m depth). Active bedforms cover 70% of the bed and are centered on the channel thalweg at water depths of 15-25 m. The remainder of the river bed is devoid of dunes, and consists of highly-consolidated and stratified sedimentary deposits that are part of the Pleistocene and Holocene substrata that lies beneath the modern Mississippi River (23% coverage). Steeply dipping channel sidewalls (30-80 degrees) are composed of the relict sediments and make up 10% of the bed area. Erosion-resistant substrate covers 13% of the channel bottom, and is frequently exposed in the deepest portions of the thalweg (25-60 m depth). Grooves and flutes are cut into this exposed substrate implying active river incision. Based on the proportion of modern sediment cover versus exposed erosion-resistant substrate on the channel bed, we propose that the lower Mississippi River is best classified as a mixed bedrock-alluvial channel.

  19. Comparison of different investigation methods to characterise alluvial gravel aquifers

    NASA Astrophysics Data System (ADS)

    Reist, Fabian; Brauchler, Ralf; Jiménez, Santos; Bühler, Lukas; Hu, Linwei; Leuenberger-West, Fanny; Bayer, Peter

    2014-05-01

    For reliable groundwater transport modelling of unconsolidated porous aquifers, high resolution characterisation of spatially heterogeneous hydraulic and transport properties is of great importance. Predictions of first-arrival times and long term behaviour depend strongly on the quality of estimated hydraulic and transport parameters. By neglecting small-scale structures such as sand lenses and sediment intra-channel deposits, predictions are hardly accurate. This paper deals with the comparison of methods to characterize hydraulic parameters governing solute transport in unconsolidated porous aquifer materials. A large number of single-well slug tests, cross-well slug tests, a pumping test and a multi-level tracer test were conducted in a shallow alluvial gravel aquifer. This facilitated describing the spatial variation of hydraulic and transport parameters with high resolution. Multi-level slug tests results show distinct positive correlation with porosity-logs and drill cores and are thus an effective means to identify and characterize subsurface structures at high resolution. Values for hydraulic conductivity gained from pumping tests and cross-well slug tests revealed good accordance but were around one order of magnitude higher than the values derived from multi-level slug tests. This might be due to the fact that the three methods are involving different test-volumes. Hence, the determination of hydraulic conductivity underlies a scale dependency: larger test volumes tend to be characterized by larger K-values. Furthermore, our pumping test results show the importance of a high sampling rate, in our case 50 Hz, in order to determine reliably the hydraulic properties storage and anisotropy of hydraulic conductivity. Although pumping tests typically estimate hydraulic parameters on large-scale, small-scale heterogeneity could also be identified and characterized. This was again possible through the high resolution records of the early time drawdown. Finally, results of multi-level tracer testing supported observations from slug tests and porosity logs.

  20. Holocene alluvial stratigraphy and response to climate change in the Roaring River valley, Front Range, Colorado, USA

    NASA Astrophysics Data System (ADS)

    Madole, Richard F.

    2012-09-01

    Stratigraphic analyses and radiocarbon geochronology of alluvial deposits exposed along the Roaring River, Colorado, lead to three principal conclusions: (1) the opinion that stream channels in the higher parts of the Front Range are relics of the Pleistocene and nonalluvial under the present climate, as argued in a water-rights trial USA v. Colorado, is untenable, (2) beds of clast-supported gravel alternate in vertical succession with beds of fine-grained sediment (sand, mud, and peat) in response to centennial-scale changes in snowmelt-driven peak discharges, and (3) alluvial strata provide information about Holocene climate history that complements the history provided by cirque moraines, periglacial deposits, and paleontological data. Most alluvial strata are of late Holocene age and record, among other things, that: (1) the largest peak flows since the end of the Pleistocene occurred during the late Holocene; (2) the occurrence of a mid- to late Holocene interval (~ 2450-1630(?) cal yr BP) of warmer climate, which is not clearly identified in palynological records; and (3) the Little Ice Age climate seems to have had little impact on stream channels, except perhaps for minor (~ 1 m) incision.

  1. Holocene alluvial stratigraphy and response to climate change in the Roaring River valley, Front Range, Colorado, USA

    USGS Publications Warehouse

    Madole, Richard F.

    2012-01-01

    Stratigraphic analyses and radiocarbon geochronology of alluvial deposits exposed along the Roaring River, Colorado, lead to three principal conclusions: (1) the opinion that stream channels in the higher parts of the Front Range are relics of the Pleistocene and nonalluvial under the present climate, as argued in a water-rights trial USA v. Colorado, is untenable, (2) beds of clast-supported gravel alternate in vertical succession with beds of fine-grained sediment (sand, mud, and peat) in response to centennial-scale changes in snowmelt-driven peak discharges, and (3) alluvial strata provide information about Holocene climate history that complements the history provided by cirque moraines, periglacial deposits, and paleontological data. Most alluvial strata are of late Holocene age and record, among other things, that: (1) the largest peak flows since the end of the Pleistocene occurred during the late Holocene; (2) the occurrence of a mid- to late Holocene interval (~2450–1630(?) cal yr BP) of warmer climate, which is not clearly identified in palynological records; and (3) the Little Ice Age climate seems to have had little impact on stream channels, except perhaps for minor (~1 m) incision. Published

  2. A multiple-point geostatistical method for characterizing uncertainty of subsurface alluvial units and its effects on flow and transport

    USGS Publications Warehouse

    Cronkite-Ratcliff, C.; Phelps, G.A.; Boucher, A.

    2012-01-01

    This report provides a proof-of-concept to demonstrate the potential application of multiple-point geostatistics for characterizing geologic heterogeneity and its effect on flow and transport simulation. The study presented in this report is the result of collaboration between the U.S. Geological Survey (USGS) and Stanford University. This collaboration focused on improving the characterization of alluvial deposits by incorporating prior knowledge of geologic structure and estimating the uncertainty of the modeled geologic units. In this study, geologic heterogeneity of alluvial units is characterized as a set of stochastic realizations, and uncertainty is indicated by variability in the results of flow and transport simulations for this set of realizations. This approach is tested on a hypothetical geologic scenario developed using data from the alluvial deposits in Yucca Flat, Nevada. Yucca Flat was chosen as a data source for this test case because it includes both complex geologic and hydrologic characteristics and also contains a substantial amount of both surface and subsurface geologic data. Multiple-point geostatistics is used to model geologic heterogeneity in the subsurface. A three-dimensional (3D) model of spatial variability is developed by integrating alluvial units mapped at the surface with vertical drill-hole data. The SNESIM (Single Normal Equation Simulation) algorithm is used to represent geologic heterogeneity stochastically by generating 20 realizations, each of which represents an equally probable geologic scenario. A 3D numerical model is used to simulate groundwater flow and contaminant transport for each realization, producing a distribution of flow and transport responses to the geologic heterogeneity. From this distribution of flow and transport responses, the frequency of exceeding a given contaminant concentration threshold can be used as an indicator of uncertainty about the location of the contaminant plume boundary.

  3. Enantioselective Construction of Cyclic Quaternary Centers: (-)-Mesembrine

    E-print Network

    Taber, Douglass

    Enantioselective Construction of Cyclic Quaternary Centers: (-)-Mesembrine Douglass F. Taber, (-)-mesembrine 1. Amide 2 should be a useful chiron for the enantioselective construction of cyclic quaternary of mesembrine2,3 and its analogues is the enantioselective construction of the chiral quaternary center.4 We

  4. A Case Study on the Importance of Local Geology on Selection of Cut-off Wall Construction Procedure

    Microsoft Academic Search

    Gülgün Yilmaz; Turhan Karadayilar; Ali Günay

    A cut-off wall was implemented for a shopping mall to be constructed in Eskisehir\\/Turkey. The subject site is located near Porsuk River on an alluvial plain. Local geology of the subject site consists of Quaternary aged alluvial deposits overlying Eosen and Neogene aged marls and limestones. In the soil investigation results, it was reported that the alluvial deposits consists of

  5. Experimental alluvial fan evolution: Channel dynamics, slope controls, and shoreline growth

    NASA Astrophysics Data System (ADS)

    Reitz, Meredith D.; Jerolmack, Douglas J.

    2012-06-01

    River deltas and alluvial fans have channelization and deposition dynamics that are not entirely understood, but which dictate the evolution of landscapes of great social, economic, and ecologic value. Our lack of a process-based understanding of fan dynamics hampers our ability to construct accurate prediction and hazard models, leaving these regions vulnerable. Here we describe the growth of a series of experimental alluvial fans composed of a noncohesive grain mixture bimodal in size and density. We impose conditions that simulate a gravel/sand fan prograding into a static basin with constant water and sediment influx, and the resulting fans display realistic channelization and avulsion dynamics. We find that we can describe the dynamics of our fans in terms of a few processes: (1) an avulsion sequence with a timescale dictated by mass conservation between incoming flux and deposit volume; (2) a tendency for flow to reoccupy former channel paths; and (3) bistable slopes corresponding to separate entrainment and deposition conditions for grains. Several important observations related to these processes are: an avulsion timescale that increases with time and decreases with sediment feed rate; fan lobes that grow in a self-similar, quasi-radial pattern; and channel geometry that is adjusted to the threshold entrainment stress. We propose that the formation of well-defined channels in noncohesive fans is a transient phenomenon resulting from incision following avulsion, and can be directly described with dual transport thresholds. We present a fairly complete, process-based description of the mechanics of avulsion and its resulting timescale on our fans. Because the relevant dynamics depend only on threshold transport conditions and conservation of mass, we show how results may be directly applied to field-scale systems.

  6. An OSL dated Middle and Late Quaternary sedimentary record in the Roer Valley Graben (southeastern Netherlands)

    NASA Astrophysics Data System (ADS)

    Schokker, Jeroen; Cleveringa, Piet; Murray, Andrew S.; Wallinga, Jakob; Westerhoff, Wim E.

    2005-11-01

    Well-dated terrestrial sedimentary sequences are important to evaluate the influence of Quaternary climate change on continental landscape evolution. The Roer Valley Graben (southeastern Netherlands) contains a 35 m thick sedimentary record of Middle and Late Quaternary fluvial, aeolian and organic deposits. Sediment provenance, depositional processes and the continuity and timing of deposition were reconstructed. Sedimentary and geochemical data reveal a change from a fluvial depositional environment to a dominance of aeolian deposits. This change may be related to increased tectonic uplift and the onset of large-scale volcanism in the Ardennes-Eifel region between 800 and 500 ka. The main source of aeolian sediments are Quaternary Rhine deposits that crop out to the northwest of the study area. Sedimentation and preservation in the Roer Valley Graben took place under humid surface conditions. These conditions occurred: (1) in a periglacial climate with permafrost; (2) at the transition from a warm-temperate to a cool climate. Dates from two internally consistent quartz Optically Stimulated Luminescence (OSL) age series in the Roer Valley Graben correspond well with the ages of related terrace deposits in the orbitally tuned Meuse river terrace flight. The OSL dates confirm the presence of organic deposits reflecting Marine Oxygen Isotope Stage (MIS) 9 or 11 and MIS 5e. This long terrestrial sequence thus provides input for the fragmentary Middle Pleistocene record of northwestern Europe and forms a possible link between the glacial history of northern Europe and the long lake and loess records of eastern and southern Europe.

  7. Quaternary fluvial archives: achievements of the Fluvial Archives Group

    NASA Astrophysics Data System (ADS)

    Bridgland, David; Cordier, Stephane; Herget, Juergen; Mather, Ann; Vandenberghe, Jef; Maddy, Darrel

    2013-04-01

    In their geomorphological and sedimentary records, rivers provide valuable archives of environments and environmental change, at local to global scales. In particular, fluvial sediments represent databanks of palaeoenvironment and palaeoclimatic (for example) of fossils (micro- and macro-), sedimentary and post-depositional features and buried soils. Well-dated sequences are of the most value, with dating provided by a wide range of methods, from radiometric (numerical) techniques to included fossils (biostratigraphy) and/or archaeological material. Thus Quaternary fluvial archives can also provide important data for studies of Quaternary biotic evolution and early human occupation. In addition, the physical disposition of fluvial sequences, be it as fragmented terrace remnants or as stacked basin-fills, provides valuable information about geomorphological and crustal evolution. Since rivers are long-term persistent features in the landscape, their sedimentary archives can represent important frameworks for regional Quaternary stratigraphy. Fluvial archives are distributed globally, being represented on all continents and across all climatic zones, with the exception of the frozen polar regions and the driest deserts. In 1999 the Fluvial Archives Group (FLAG) was established, as a working group of the Quaternary Research Association (UK), aimed at bringing together those interested in such archives. This has evolved into an informal organization that has held regular biennial combined conference and field-trip meetings, has co-sponsored other meetings and conference sessions, and has presided over two International Geoscience Programme (IGCP) projects: IGCP 449 (2000-2004) 'Global Correlation of Late Cenozoic Fluvial Deposits' and IGCP 518 (2005-2007) 'Fluvial sequences as evidence for landscape and climatic evolution in the Late Cenozoic'. Through these various activities a sequence of FLAG publications has appeared, including special issues in a variety of journals, amassing a substantial volume of information on fluvial archives worldwide. This presentation will highlight some of these data and will describe important patterns observed and interpretations arising therefrom.

  8. Robustness of Quaternary glacial cycles

    NASA Astrophysics Data System (ADS)

    Ganopolski, Andrei; Brovkin, Victor; Calov, Reinhard

    2015-04-01

    In spite of significant progress in paleoclimate reconstructions and modeling some aspects of Quaternary climate cycles are still poorly understood. Among them is the question of whether glacial cycles are deterministic and solely externally forced or, at least partially, they are stochastic. The answer to this question can only be obtained using a comprehensive Earth system models which incorporates all major components of the Earth system - atmosphere, ocean, land surface, northern hemisphere ice sheets, terrestrial biota and soil carbon, aeolian dust and marine biogeochemistry. Here, we used the Earth system model of intermediate complexity CLIMBER-2. The model was optimally tuned to reproduce climate, ice volume and CO2 variability for the last 0.8 million years. Using the same model version, we performed a large set of simulations covering the entire Quaternary (3 million years). By starting the model at different times (with the time step of 100,000 years) and using identical initial conditions we run the model for 500,000 years using the Earth's orbital variations as the only prescribed radiative forcing. We show that within less than 100,000 years after the beginning of each experiment the modeling results converge to the same solution which depends only on the orbital forcing and boundary conditions, such as topography and terrestrial sediment thickness for the ice sheets or volcanic CO2 outgassing for the carbon cycle. By using only several sets of the Northern Hemisphere orography and sediment thickness which represent different stages of landscape evolution during Quaternary, we are able to reproduce all major regimes of Quaternary long-term climate variability. Our results thus strongly support the notion that Quaternary glacial cycles are deterministic and externally forced.

  9. Fluvial sedimentation following Quaternary eruptions of Mount St. Helens, Washington

    SciTech Connect

    Janda, R.J.; Meyer, D.F

    1985-01-01

    Depositional records of convulsive volcanic events at Mount St. Helens are in many places obscured by rapid fluvial erosion and deposition close to the volcano. Some major eruptions are recorded primarily by lahars and alluvium deposited tens of kilometers away. About 35 percent of the distinctive hummocky topography of the 1980 North Fork Toutle debris avalanche deposit now resembles an alluvial fan or a braided glacial outwash plain covered with 10 m or more of alluvium. Deposits of small (20 x 10/sup 6/m/sup 3/) but damaging lahars, such as those generated in the afternoon of 18 May 1980 and on 19 March 1982, have been largely eroded away. Rivers draining rapidly eroding areas surrounding Mount St. Helens presently have sediment yields that are among the highest in the world for nonglaciated streams of comparable size. These sediment loads are capable of causing aggradation-induced flooding in populated areas along the lower Toutle and Cowlitz Rivers. Sediment retention structures and dredging have prevented such flooding. Immediately following prehistoric eruptions, however, coarse-grained volcanic alluvium was deposited in the Cowlitz River to levels more than 1 m above the 1980 mud flow inundation level. Post-1980 rapid landscape modifications and high sediment yields are noteworthy because the eruption-impact area has not yet had a major regional storm and potentially catastrophic breachings of avalanche-impounded lakes have been prevented through engineering measures.

  10. Reconstructing Holocene fluvial activity in Ireland using alluvial radiocarbon dates

    NASA Astrophysics Data System (ADS)

    Turner, Jonathan; Macklin, Mark; Jones, Anna

    2010-05-01

    Advances in fluvial geochronologies and multi-proxy environmental correlatives are providing increasingly robust models of river response to Holocene environmental change. At the forefront of recent scientific progress is the development and analysis of databases of fluvial radiocarbon dates, where particular emphasis is given to terminus post quem (‘change after') radiocarbon dates that mark the onset of alluviation linked to episodes of enhanced flooding. Here we report on the first attempt to apply these meta-analysis techniques to dated fluvial deposits in Ireland, which offer tremendous potential for recording climate changes associated with shifts in meridional atmospheric circulation, largely free from the effects of continentality in the east. The resulting Irish fluvial radiocarbon database is considerably smaller than examples from other European countries, such as Germany, Poland, Spain and the UK, and a patchy geographical distribution of dated sites across Ireland highlights the relative dearth of Irish fluvial research up to now. Despite a comparatively small number of significant ‘change after' radiocarbon dates, however, the application of generic meta-analysis techniques reveals a pattern of Holocene flooding that is consistent with widely cited palaeoclimate proxies for regional temperature and precipitation. The Irish flood record also closely matches that derived from an established and much larger UK radiocarbon database, thereby corroborating the growing body of evidence that supports an underlying climate forcing of fluvial activity during much of the Holocene. Fluvial systems in Ireland are shown to be sensitive to climate, but the majority of major radiocarbon-dated flooding episodes appear to lag the UK by ca. 100 years. Although this may be the result of database precision, we suggest that the hydrological buffering and sponge effects of widespread peatland cover across Ireland may have impeded hydrological connectivity during Holocene flooding episodes. In addition, this investigation reveals systematically lower sedimentation rates across Ireland compared to the UK, which may have reduced the geomorphic effectiveness of fluvial sediment archives to record major flood events. These considerations, together with an increasing focus on regional variations in fluvial activity across the Holocene, can only be properly addressed with a more concerted and expanded programme of Holocene fluvial research in Ireland.

  11. A reappraisal of the late Quaternary fossil vertebrates of Pyramid Valley Swamp, North Canterbury, New Zealand

    Microsoft Academic Search

    R. N. Holdaway; T. H. Worthy

    1997-01-01

    The late Quaternary fossil vertebrate fauna from deposits at Pyramid Valley, North Canterbury, New Zealand is reassessed. The faunal composition as contained in previous lists is updated, and minimum numbers of individuals represented are given. Measures of faunal diversity are presented and compared with values for present New Zealand systems and other fossil sites. The revised faunal list includes a

  12. First Quaternary Fossil Record of Caecilians from a Mexican Archaeological Site

    Microsoft Academic Search

    Thomas A. Wake; Marvalee H. Wake; Richard G. Lesure

    1999-01-01

    A single vertebra from an Early Formative period archaeological site in coastal Chiapas, México, is identified as belonging to the amphibian Dermophis mexicanus (Duméril and Bibron) 1841 (Amphibia: Gymnophiona: Caeciliidae). The vertebra was recovered from deposits dated to approximately 1200–1350 B.C. The specimen represents the first Quaternary fossil record for gymnophiones. Its presence suggests the possible role of the species

  13. Biodegradation of Petroleum Hydrocarbon Vapors In Unsaturated Alluvial Sand

    Microsoft Academic Search

    P. Höhener; C. Duwig; G. Pasteris; N. Dakhel; K. Kaufmann; D. Werner

    2002-01-01

    Biodegradation rates are critical parameters in models aimed at predicting the nat- ural attenuation of volatile organic compounds (VOCs) in the unsaturated zone. In this study the kinetic rate laws for the aerobic biodegradation of selected petroleum hydrocarbons and MTBE were investigated in unsaturated alluvial sand exposed to the vapors from a fuel mixture. Laboratory column and batch experiments were

  14. HYDRAULIC ANALYSIS OF BASEFLOW AND BANK STORAGE IN ALLUVIAL STREAMS

    EPA Science Inventory

    This paper presents analytical solutions, which describe the effect of time-variable net recharge (net accretion to water table) and bank storage in alluvial aquifers on the sustenance of stream flows during storm and inter-storm events. The solutions relate the stream discharge,...

  15. On Earthquake Ground Motion and Structural Response in Alluvial Valleys

    E-print Network

    Shewchuk, Jonathan

    On Earthquake Ground Motion and Structural Response in Alluvial Valleys By Jacobo Bielak 1 , Member amplification and structural dam­ age due to local site conditions in sedimentary valleys during earthquakes the 1988 Armenia Earthquake. A more realistic two­dimensional finite element analysis is performed herein

  16. Post-last glacial alluvial fan and talus slope associations (Northern Calcareous Alps, Austria): A proxy for Late Pleistocene to Holocene climate change

    NASA Astrophysics Data System (ADS)

    Sanders, Diethard; Ostermann, Marc

    2011-08-01

    Near Innsbruck city (Austria, Eastern Alps), following the Last Glacial Maximum (LGM), an alluvial fan-to-talus slope succession was supplied from a carbonate-rock cliff more than 1000 m in height. 234U/ 230Th ages of 9.5 to 9.37 isotope kyrs of diagenetic cements in the alluvial-fan succession suggest that the fan/talus deposit accumulated mainly during late-glacial to, perhaps, early Holocene times. The deepest-exposed interval of the fan succession contains cracked lithoclasts probably fractured by overburden from late-glacial ice; this interval is topped by an intra-sequence unconformity. Following final glacial retreat, and rapid aggradation of the alluvial fan and talus slope, the geomorphic regime changed to erosion, as recorded by fanhead trenching and cutting of fluvial terraces, abandonment and vegetating of scree slopes, and excavation of 'talus flatirons'. The changeover from the accumulation of fan and talus to abandonment and dissection probably took place during the terminal late-glacial interval to perhaps the early Holocene. This erosional regime persists until present. A record of rapid late-glacial to early Holocene accumulation of an alluvial fan/talus deposit followed by: (i) abandonment and vegetation growth, combined with (ii) cutting of intra-sequence unconformities of limited lateral extent, is typical of Alpine mountain-flank deposystems situated at comparatively low altitudes. This record consists of (a) an autocyclic component, that is, progressive lowering of sediment input due to onlap and burial of freshly-deglaciated mountain flanks supplying alluvial fans and talus slopes, and (b) an allocyclic component, that is, deglacial climatic warming and upward rise of an altitudinal range with a maximum number of freeze-thaw cycles ('talus window'), also leading to progressive vegetation-induced hillslope stabilization and lowering of scree production.

  17. Shallow subsurface geology of part of the Savannah River alluvial valley in the upper Coastal Plain of Georgia and South Carolina

    USGS Publications Warehouse

    Leeth, D.C.; Nagle, D.D.

    1996-01-01

    The depth to which Coastal Plain rivers incise underlying formations is an important control on local and regional hydrologic flow systems. In order to clarify these stream/aquifer relations, a better understanding of the shallow subsurface geology of the Savannah River was necessary. To accomplish this, three drillhole transects were completed across a part of the Savannah River alluvial valley in September 1993, and five geologic sections were constructed from the data. The alluvium is coarser, more angular, and more poorly sorted than the underlying formations, and lithologic differences between the strata are readily apparent, especially in areas where the underlying strata are of marine origin. Inspection of the transects indicates an asymmetry to both the alluvial terrace complex and the underlying bedrock strath. The alluvium thins in a coastward direction; and similarly, bulk-grain size diminishes in a downstream direction. This phenomenon has remained constant over time and is most likely a function of the change in slope which occurs when the river traverses the Fall Line north of the study area. The maximum thickness of the alluvial valley fill is 50 ft. The elevation of the unconformity between the alluvium and the underlying formation is far below the lowest elevation of the modern-day thalweg, indicating that the alluvial system has aggraded to form the modern-day Savannah River Valley. Formerly, the Savannah River was located immediately adjacent to and east of the modern floodplain when the river valley was formed by a cyclic pattern of infilling and subsequent entrenchment that gave rise to an irregular bedrock surface beneath the depositional terrace system. After this depositional period, the river migrated to the southwest and began a period of downcutting that ended with the formation of the unconformity (erosional terrace) that lies some 45 ft. beneath the modern-day river. The protracted southwestward migration of the river system is perhaps the best indication that pre-historic tectonism exerts an influence on the modern-day alluvial system.

  18. Introduction Preliminaries Construction of Quaternary Sequences Construction of Familes References New Construction of Quaternary Sequences

    E-print Network

    No, Jong-Seon

    Introduction Preliminaries Construction of Quaternary Sequences Construction of Familes References New Construction of Quaternary Sequences with Good Correlation Using Binary Sequences with Good University May 28, 2010 May 28, 2010 2010 CITS 2nd 1/ 34 #12;Introduction Preliminaries Construction

  19. Transport of Escherichia coli and solutes during waste water infiltration in an urban alluvial aquifer.

    PubMed

    Foppen, J W A; van Herwerden, M; Kebtie, M; Noman, A; Schijven, J F; Stuyfzand, P J; Uhlenbrook, S

    2008-01-01

    Recharge of waste water in an unconsolidated poorly sorted alluvial aquifer is a complex process, both physically and hydrochemically. The aim of this paper is to analyse and conceptualise vertical transport mechanisms taking place in an urban area of extensive wastewater infiltration by analysing and combining the water balance, the microbial (Escherichia coli) mass balance, and the mass balance for dissolved solutes. For this, data on sediment characteristics (grain size, organic carbon, reactive iron, and calcite), groundwater levels, and concentrations of E. coli in groundwater and waste water were collected. In the laboratory, data on E. coli decay rate coefficients, and on bacteria retention characteristics of the sediment were collected via column experiments. The results indicated that shallow groundwater, at depths of 50 m below the surface, was contaminated with E. coli concentrations as high as 10(6) CFU/100 mL. In general, E. coli concentrations decreased only 3 log units from the point of infiltration to shallow groundwater. Concentrations were lower at greater depths in the aquifer. In laboratory columns of disturbed sediments, bacteria removal was 2-5 log units/0.5 cm column sediment. Because of the relatively high E. coli concentrations in the shallow aquifer, transport had likely taken place via a connected network of pores with a diameter large enough to allow bacterial transport instead of via the sediment matrix, which was inaccessible for bacteria, as was clear from the column experiments. The decay rate coefficient was determined from laboratory microcosms to be 0.15 d(-1). Assuming that decay in the aquifer was similar to decay in the laboratory, then the pore water flow velocity between the point of infiltration and shallow groundwater, coinciding with a concentration decrease of 3 log units, was 0.38 m/d, and therefore, transport in this connected network of pores was fast. According to the water balance of the alluvial aquifer, determined from transient groundwater modelling, groundwater flow in the aquifer was mainly in vertical downward direction, and therefore, the mass balance for dissolved solutes was simulated using a 1D transport model of a 200 m column of the Quaternary Alluvium aquifer. The model, constructed with PHREEQC, included dual porosity, and was able to adequately simulate removal of E. coli, cation-exchange, and nitrification. The added value of the use of E. coli in this study was the recognition of relatively fast transport velocities occurring in the aquifer, and the necessity to use the dual porosity concept to investigate vertical transport mechanisms. Therefore, in general and if possible, microbial mass balances should be considered more systematically as an integral part of transport studies. PMID:17854950

  20. Geostatistical simulations of alluvial sandbodies in the Triassic series of the Chaunoy field, France

    SciTech Connect

    Eschard, R.; Desaubliaux, G.; Eemouzy, P. (Institut Francais du Petrole, Rueil Malmaison (France)); Bacchiana, C.; Parpant, J.; Chautru, J.M.

    1993-09-01

    Chaunoy field, the largest oil field of the Paris basin, is exploiting heterogeneous reservoirs deposited during the Triassic in a large alluvial fan/lacustrine complex. The construction of a realistic reservoir model is difficult in such a setting because of the highly complex architecture of single reservoir units. Geostatistical simulations therefore have been performed to take into account the reservoir heterogeneities in the fluid flow modeling. A first layering has been determined from sedimentological and sequence stratigraphic analysis. The series was deposited in an alluvial outer fan environment. A lower siliciclastic member shows four heterogeneous sand sheets (7 m thick), which have been correlated across the field. Each of them is made up of stacked single channel sequences. The sand sheets are separated by extensive lacustrine and flood plain mudstone layers acting as permeability barriers. An upper siliciclastic/dolomitic member has been divided into two units with porous conglomeratic channels interfingered with cemented lagoonal dolomites. Proportional curves in lithofacies have confirmed this layering, showing the continuity of the permeability barriers, and the variogram analysis has shown that the well spacing is larger than the channel width. Simulations in lithofacies have been performed with the Heresim software using three different variogram ranges (small, medium, and large values). Because a good correlation exists between the lithofacies and the petrophysical attributes, a transcription of the lithofacies simulations into petrophysical attributes therefore was easy and realistic. Scaling-up techniques have given fluid-flow models corresponding to the three correlation ranges. Comparison of the global results of the fluid flow simulations with the observed production history enabled us to choose the more relevant case. The the model using the selected correlation range helped determine optimum well spacing.

  1. Quaternary glaciation of Mount Everest

    Microsoft Academic Search

    Lewis A. Owen; Ruth Robinson; Douglas I. Benn; Robert C. Finkel; Nicole K. Davis; Chaolu Yi; Jaakko Putkonen; Dewen Li; Andrew S. Murray

    2009-01-01

    The Quaternary glacial history of the Rongbuk valley on the northern slopes of Mount Everest is examined using field mapping, geomorphic and sedimentological methods, and optically stimulated luminescence (OSL) and 10Be terrestrial cosmogenic nuclide (TCN) dating. Six major sets of moraines are present representing significant glacier advances or still-stands. These date to >330ka (Tingri moraine), >41ka (Dzakar moraine), 24–27ka (Jilong

  2. Quaternary ecology: A paleoecological perspective

    SciTech Connect

    Delcourt, H.R.; Delcourt, P.A.

    1991-01-01

    This book considers issues and problems in ecology which may be illuminated, if not solved, by considering paleoecology. The five central chapters include a discussion of application of Quaternary ecology to future global climate change, including global warming. Other areas presented include: population dispersal, invasions, expansions, and migrations; plant successions; ecotones; factors in community structure; ecosystem patterns and processes. Published case studies are numerous. The role played by continuing climatic change in vegetation change is acknowledged but not stressed.

  3. 40 CFR 721.10511 - Quaternary ammonium salts (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Quaternary ammonium salts (generic). 721.10511 Section 721...Substances § 721.10511 Quaternary ammonium salts (generic). (a) Chemical substance...identified generically as quaternary ammonium salts (PMNs P-07-320,...

  4. 21 CFR 172.165 - Quaternary ammonium chloride combination.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 false Quaternary ammonium chloride combination...Preservatives § 172.165 Quaternary ammonium chloride combination... The food additive, quaternary ammonium chloride combination...7.0-8.0; total amines, maximum 1 percent...

  5. 21 CFR 172.165 - Quaternary ammonium chloride combination.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 false Quaternary ammonium chloride combination...Preservatives § 172.165 Quaternary ammonium chloride combination... The food additive, quaternary ammonium chloride combination...7.0-8.0; total amines, maximum 1 percent...

  6. 40 CFR 721.10569 - Tricyclic quaternary amine salt (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Tricyclic quaternary amine salt (generic). 721.10569... § 721.10569 Tricyclic quaternary amine salt (generic). (a...identified generically as tricyclic quaternary amine salt (PMN...

  7. 21 CFR 172.165 - Quaternary ammonium chloride combination.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 false Quaternary ammonium chloride combination...Preservatives § 172.165 Quaternary ammonium chloride combination... The food additive, quaternary ammonium chloride combination...7.0-8.0; total amines, maximum 1 percent...

  8. 21 CFR 172.165 - Quaternary ammonium chloride combination.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2009-04-01 true Quaternary ammonium chloride combination...Preservatives § 172.165 Quaternary ammonium chloride combination... The food additive, quaternary ammonium chloride combination...7.0-8.0; total amines, maximum 1 percent...

  9. 21 CFR 172.165 - Quaternary ammonium chloride combination.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 false Quaternary ammonium chloride combination...Preservatives § 172.165 Quaternary ammonium chloride combination... The food additive, quaternary ammonium chloride combination...7.0-8.0; total amines, maximum 1 percent...

  10. 40 CFR 721.10569 - Tricyclic quaternary amine salt (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Tricyclic quaternary amine salt (generic). 721.10569... § 721.10569 Tricyclic quaternary amine salt (generic). (a...identified generically as tricyclic quaternary amine salt (PMN...

  11. Changes in alluvial architecture associated with Eocene hyperthermals: Preliminary results from the Bighorn Basin Coring Project

    NASA Astrophysics Data System (ADS)

    Acks, R.; Kraus, M. J.

    2012-12-01

    The Paleocene-Eocene Thermal Maximum (PETM) was followed by two lesser hyperthermal events: ETM2 and H2 both at ~53.7 Ma. The carbon isotope excursion for ETM2 was approximately half that of the PETM and the H2 excursion even smaller, indicating lower increases in temperature than during the PETM. The paleohydrologic responses to these events are less well understood than the response to PETM warming. Although the ETM2 and H2 events are better known from marine than continental strata, both events have been identified from outcrops of the alluvial Willwood Formation from the Deer Creek and Gilmore Hill areas of the Bighorn Basin, Wyoming (Abels et al., 2012). Here, we analyze two cores drilled from stratigraphically equivalent Willwood strata from Gilmore Hill. The cores provide an opportunity to examine the impact of these events on the architecture of fluvial strata. Willwood strata are composed largely of channel sandstones, heterolithic deposits generated by channel avulsion, and paleosols that formed on overbank deposits. The paleosols provide qualitative and quantitative information on changes in soil moisture and precipitation through this interval. The cores also show a distinct change in the stacking of paleosols The core is subdivided into three parts: (1) the lowest ~third has thinner, more densely spaced paleosols, (2) the middle has thicker paleosols that are more widely spaced, and (3) the upper third has thicker and more common channel sandstones interspersed with avulsion deposits and fewer red paleosols; this corresponds to the hyperthermal interval. In particular, a ~20 m thick sandstone complex caps the section and appears to truncate part of the hyperthermal interval. Although vertical variations in alluvial architecture can reflect tectonic or climatic change, the correspondence of the sandstone-rich part of the cores with the hyperthermals suggests climate was the major control on their formation. Thick purple paleosols associated with the hyperthermals at Deer Creek suggest wetter conditions, and our preliminary interpretation is that a change to wetter conditions caused increased discharge and deposition of coarser (sandy) sediment. The thick sandstone complex at Gilmore Hill is underlain by paleosols with abundant calcrete nodules, which indicate drier soil conditions prior to deposition of the sandstone, and the change from drier to wetter conditions probably also caused increased sediment yield.

  12. Experimental investigation into Quaternary badland geomorphic development

    NASA Astrophysics Data System (ADS)

    Kasanin-Grubin, Milica; Kuhn, Nikolaus; Yair, Aaron; Bryan, Rorke; Schwanghart, Wolfgang

    2010-05-01

    Badland morphology is commonly linked to lithological properties of the bedrock. However, recent investigations indicate that the geomorphic development is sensitive to climate and in particular to precipitation characteristics. In this study, the precipitation characteristics that are critical for the Quaternary landscape development in the Dinosaur Badlands in Alberta, Canada, and Zin Valley Badlands, Negev Desert, Israel are investigated. Runoff, erosion and weathering were simulated in the field and the laboratory to determine rates for modeling different precipitation regimes. Currently, the geomorphic development in the Dinosaur badlands is characterized by weathering/supply limited conditions, leading to slope retreat independent of lithology. In the Negev, transport limited conditions cause frequent runoff discontinuity, creating a pattern of areas dominated by erosion or deposition. The results of the weathering and erosion experiments show that the balance between snowmelt induced weathering in the spring and summer rainfall and erosion determine the rate of slope retreat in the Dinosaur Badlands. In the Zin Valley, on the other hand, the magnitude of the individual rainstorms determines whether a slope section is eroded or acts as a sediment sink. The experiments illustrate that the badland slopes experienced an auto-stabilization during the Quaternary in the Zin Valley. In the Dinosaur Badlands Holocene climatic variations have not caused a permanent differentiation of patterns of erosion and deposition. Based on these results the reaction of badland slopes to changing precipitation characteristics was modeled. In their current state, both badland slope systems appear to be fairly stable against climate change in the range of those occurring during the Holocene. However, the stability is achieved in different ways. In the Dinosaur Badlands, weathering rates are low compared to erosion capacity, maintaining continuous evacuation of sediment from slopes to the flood planes of the Red Deer River system. Only a very pronounced contrast between winter weathering and drier summers would generate a colluvium and thus change slope hydrology. In the Zin Valley the development of a thick colluvium at the foot of the slopes has increased infiltration capacity, reducing runoff and sediment yield into the floodplain. Here, only an increase in rainfall magnitude would improve runoff continuity and induce the erosion of the colluvium. This would in turn reduce infiltration capacity and thus initiate a positive feedback on runoff and sediment yield into the Zin River. Overall, Holocene climate change appears to be insufficient to change the geomorphic development in both badlands. However, this stability is achieved not despite of climate, but because of the specific history of geomorphic development. In addition, the combination of erosion and weathering experiments with numerical modeling demonstrates the versatility of Experimental Geomorphology in landscape evolution studies.

  13. Surface interaction of quaternary amines with hair

    Microsoft Academic Search

    B. C. Beard; J. Hare

    2002-01-01

    Surface analysis by X-ray photoelectron spectroscopy (XPS) has shown specific 1?1 (ionic) interaction between cationic alkyl\\u000a quaternary surfactant molecules and the anionic sulfonate groups present on the hair surface. The primary driving force for\\u000a the adsorption of alkyl quaternary amine molecules to the surface of the hair from aqueous solution is the ionic interaction\\u000a between quaternary groups and the surface

  14. Quaternary coastal evolution of Oman (Arabian Peninsula) - a quantitative approach

    NASA Astrophysics Data System (ADS)

    Hoffmann, G.; Rupprechter, M.; Roepert, A.; Quraishi, K. Al; Balushi, N. Al; Grützner, C.; Reicherter, K.

    2012-04-01

    The paper reviews the Quaternary coastal evolution of Oman. Emphasise is put on quantifying the different forcing factors. The plate tectonic setting, the Quaternary climate evolution, the sea-level history and the impact of natural hazards are identified as key factors of coastal evolution. The Arabian Plate is characterized by a northward movement forming a continent-continent collision zone in the west and the Makran Subduction Zone in the east. As a result differential land movement is observable in Oman. The Quaternary climate evolution is well understood. Besides other proxies notably spelothems and aeolian deposits allow to draw a consistent picture. It is understood that changes in the position of the intertropical convergence zone result in intensity-changes of the summer monsoon. These changes are related to global atmospheric circulation patterns. Data on the sea-level history are sparse; despite general assumptions of a sea-level lowstand, correlating with the last glacial maximum, resulting in terrestrial conditions within the Arabian Gulf. Furthermore, a mid-Holocene sea level highstand in the range of +2m is documented in several locations. The coastlines of Oman are affected by tsunami and hurricanes. However, almost no instrumental or historical data on the impact of such natural hazards are available due to the isolation of the country in the past. Several Quaternary deposits have been investigated in a reconnaissance survey. There is sound geological evidence for a tsunami to have affected the coastline in 1945, with the possibility of older tsunami events being also recorded in the geological record. There is strong evidence of differential land movement along the coastline; locally indicated by marine terraces in elevations of up to 400m (Rupprechter at al. 2012). By quantifying the differential land movement for numerous sites, the sea-level history will be revealed. Ultimately the data will be utilized to form the base of a modeling approach. Furthermore, a sedimentary archive of past precipitation events is documented which will allow reconstructing frequency and intensity of precipitation events and may indicate the impact of past hurricanes. It is concluded that the geological archives are suitable to quantify the forcing factors of Quaternary coastal evolution on different time scales and that the recurrence intervals of natural hazards will be revealed. Proxy data will be gained in subsequent investigations. This allows a scientific based holistic approach for an integrated coastal zone management that helps to formulate adaptation strategies with regard to global warming and expected environmental changes.

  15. Magnitude of late Quaternary left-lateral displacements along the north edge of Tibet

    NASA Technical Reports Server (NTRS)

    Peltzer, Gilles; Tapponnier, Paul; Armijo, Rolando

    1989-01-01

    Images taken by the earth observation satellite SPOT of the Quaternary morphology at 18 sites on the 2000-kilometer-long Altyn Tagh fault at the north edge of Tibet demonstrate that it is outstandingly active. Long-term, left-lateral strike-slip offsets of stream channels, alluvial terrace edges, and glacial moraines along the fault cluster between 100 and 400 meters. The high elevation of the sites, mostly above 4000 meters in the periglacial zone, suggests that most offsets resulted from slip on the fault since the beginning of the Holocene. These data imply that slip rates are 2 to 3 centimeters per year along much of the fault length and support the hypothesis that the continuing penetration of India into Asia forces Tibet rapidly toward the east.

  16. Quaternary crustal deformation along a major branch of the San Andreas fault in central California

    USGS Publications Warehouse

    Weber, G.E.; Lajoie, K.R.; Wehmiller, J. F.

    1979-01-01

    Deformed marine terraces and alluvial deposits record Quaternary crustal deformation along segments of a major, seismically active branch of the San Andreas fault which extends 190 km SSE roughly parallel to the California coastline from Bolinas Lagoon to the Point Sur area. Most of this complex fault zone lies offshore (mapped by others using acoustical techniques), but a 4-km segment (Seal Cove fault) near Half Moon Bay and a 26-km segment (San Gregorio fault) between San Gregorio and Point Ano Nuevo lie onshore. At Half Moon Bay, right-lateral slip and N-S horizontal compression are expressed by a broad, synclinal warp in the first (lowest: 125 ka?) and second marine terraces on the NE side of the Seal Cove fault. This structure plunges to the west at an oblique angle into the fault plane. Linear, joint0controlled stream courses draining the coastal uplands are deflected toward the topographic depression along the synclinal axis where they emerge from the hills to cross the lowest terrace. Streams crossing the downwarped part of this terrace adjacent to Half Moon Bay are depositing alluvial fans, whereas streams crossing the uplifted southern limb of the syncline southwest of the bay are deeply incised. Minimum crustal shortening across this syncline parallel to the fault is 0.7% over the past 125 ka, based on deformation of the shoreline angle of the first terrace. Between San Gregorio and Point Ano Nuevo the entire fault zone is 2.5-3.0 km wide and has three primary traces or zones of faulting consisting of numerous en-echelon and anastomozing secondary fault traces. Lateral discontinuities and variable deformation of well-preserved marine terrace sequences help define major structural blocks and document differential motions in this area and south to Santa Cruz. Vertical displacement occurs on all of the fault traces, but is small compared to horizontal displacement. Some blocks within the fault zone are intensely faulted and steeply tilted. One major block 0.8 km wide east of Point Ano Nuevo is downdropped as much as 20 m between two primary traces to form a graben presently filling with Holocene deposits. Where exposed in the sea cliff, these deposits are folded into a vertical attitude adjacent to the fault plane forming the south-west margin of the graben. Near Point Ano Nuevo sedimentary deposits and fault rubble beneath a secondary high-angle reverse fault record three and possibly six distinct offset events in the past 125 ka. The three primary fault traces offset in a right-lateral sense the shoreline angles of the two lowest terraces east of Point Ano Nuevo. The rates of displacement on the three traces are similar. The average rate of horizontal offset across the entire zone is between 0.63 and 1.30 cm/yr, based on an amino-acid age estimate of 125 ka for the first terrace, and a reasonable guess of 200-400 ka for the second terrace. Rates of this magnitude make up a significant part of the deficit between long-term relative plate motions (estimated by others to be about 6 cm/yr) and present displacement rates along other parts of the San Andreas fault system (about 3.2 cm/yr). Northwestward tilt and convergence of six marine terraces northeast of Ano Nuevo (southwest side of the fault zone) indicate continuous gentle warping associated with right-lateral displacement since early or middle Pleistocene time. Minimum local crustal shortening of this block parallel to the fault is 0.2% based on tilt of the highest terrace. Five major, evenly spaced terraces southeast of Ano Nuevo on the southwest flank of Mt. Ben Lomond (northeast side of the fault zone) rise to an elevation of 240 m, indicating relatively constant uplift (about 0.19 m/ka and southwestward tilt since Early or Middle Pleistocene time (Bradley and Griggs, 1976). ?? 1979.

  17. Hypogene and supergene alteration of the zeolite-bearing pyroclastic deposits at Tell Rimah, Jordan, and rift-related processes along the Dead-Sea-Transform Fault System during the Quaternary

    NASA Astrophysics Data System (ADS)

    Dill, H. G.; Techmer, A.; Botz, R.; Dohrmann, R.; Kaufhold, S.

    2012-09-01

    The boundary between the Arabian and African plates, is marked in the Middle East by one of the most prominent deep-seated lineamentary structures, called the Dead-Sea-Transform Fault System (DSTFS). Structural and mineralogical processes related to the DSTFS were correlated with equivalent processes leading to the alteration of pyroclastic deposits of alkali-olivine basaltic to nepheline basaltic composition which formed during a time span of less than 0.5 Ma. The large deposit of Tell Rimah, Jordan, is operated for the exploitation of zeolites, tuffs, and as pozzolana raw material. Four discrete stages of mineralizations have been distinguished from each other within these volcanic-hosted mineral deposits. (1) Hypogene syneruptive alteration of pyroclastic rocks produced siliceous gels ("allophane"), smectite, analcime, and phillipsite in vesicles when the groundwater level was low in the rift basin of the DSTFS. The lake-level lowstand caused the fluid system in the pyroclastic cone to become self-sufficient and it has been considered as a closed hydrothermal system. (2) Periods of tectonic and magmatic quiescence grinded the detrital sedimentation in the rift basin to a halt, while triggering a supergene alteration in the eruptive cones on the adjacent Arabian Plate. (3) Epigenetic alteration affected the pyroclastic rocks in the distal part of the DSTFS as a result of a rising water level. The water gradually filled the pore space of the permeable pyroclastic deposits almost to completeness and caused meniscus and blocky cements of calcite, phillipsite and chabazite to develop. In the rift basin, contemporaneously with the alteration of the pyroclastic rocks, freshwater limestones formed on calcareous bedrocks. Ba and Mn minerals in these freshwater limestones were supplied by subaquatic brines. Subsequently, a drastic lowering of the lake water level in the DSTFS converted the system of subaquatic freshwater limestones into subaerial tufa and travertine. As long as the basal parts of the pyroclastic units at Tell Rimah were in the reaches of the saline groundwaters, calcite and faujasite developed in the pyroclastic host rocks. (4) Another lake level lowstand within the rift basin caused the pyroclastic host rocks to get emerged and forced zeolite-carbonate mineralization in the tuffs to a complete stillstand. Hypogene and supergene alteration in these phreatomagmatic-strombolian pyroclastic cones of the Pleistocene x were correlated with lake high- and lowstands in the adjacent rift basin along the DSTFS. The results obtained by current tectono-morphological studies of the rift-related alteration of pyroclastic rocks along the DSTFS may also be applied to basin-and-swell-topographies elsewhere in the world. The current studies involved microscopy supplemented by SEM-EDX, X-ray diffraction analysis, mid (MIR) and far (FIR) infrared spectroscopy. Major and trace elements were analyzed by X-ray fluorescence spectrometry (XRF). C- and O isotope analyses were conducted on carbonate minerals, which were also targeted on by radiocarbon dating.

  18. Geomorphic and hydraulic controls on large-scale riverbank failure on a mixed bedrock-alluvial river system, the River Murray, South Australia: a bathymetric analysis.

    NASA Astrophysics Data System (ADS)

    De Carli, E.; Hubble, T.

    2014-12-01

    During the peak of the Millennium Drought (1997-2010) pool-levels in the lower River Murray in South Australia dropped 1.5 metres below sea level, resulting in large-scale mass failure of the alluvial banks. The largest of these failures occurred without signs of prior instability at Long Island Marina whereby a 270 metre length of populated and vegetated riverbank collapsed in a series of rotational failures. Analysis of long-reach bathymetric surveys of the river channel revealed a strong relationship between geomorphic and hydraulic controls on channel width and downstream alluvial failure. As the entrenched channel planform meanders within and encroaches upon its bedrock valley confines the channel width is 'pinched' and decreases by up to half, resulting in a deepening thalweg and channel bed incision. The authors posit that flow and shear velocities increase at these geomorphically controlled 'pinch-points' resulting in complex and variable hydraulic patterns such as erosional scour eddies, which act to scour the toe of the slope over-steepening and destabilising the alluvial margins. Analysis of bathymetric datasets between 2009 and 2014 revealed signs of active incision and erosional scour of the channel bed. This is counter to conceptual models which deem the backwater zone of a river to be one of decelerating flow and thus sediment deposition. Complex and variable flow patterns have been observed in other mixed alluvial-bedrock river systems, and signs of active incision observed in the backwater zone of the Mississippi River, United States. The incision and widening of the lower Murray River suggests the channel is in an erosional phase of channel readjustment which has implications for riverbank collapse on the alluvial margins. The prevention of seawater ingress due to barrage construction at the Murray mouth and Southern Ocean confluence, allowed pool-levels to drop significantly during the Millennium Drought reducing lateral confining support to the over-steepened channel margins triggering large-scale riverbank failure.

  19. An aminostratigraphy for the British Quaternary based on Bithynia opercula

    PubMed Central

    Penkman, Kirsty E.H.; Preece, Richard C.; Bridgland, David R.; Keen, David H.; Meijer, Tom; Parfitt, Simon A.; White, Tom S.; Collins, Matthew J.

    2013-01-01

    Aminostratigraphies of Quaternary non-marine deposits in Europe have been previously based on the racemization of a single amino acid in aragonitic shells from land and freshwater molluscs. The value of analysing multiple amino acids from the opercula of the freshwater gastropod Bithynia, which are composed of calcite, has been demonstrated. The protocol used for the isolation of intra-crystalline proteins from shells has been applied to these calcitic opercula, which have been shown to more closely approximate a closed system for indigenous protein residues. Original amino acids are even preserved in bithyniid opercula from the Eocene, showing persistence of indigenous organics for over 30 million years. Geochronological data from opercula are superior to those from shells in two respects: first, in showing less natural variability, and second, in the far better preservation of the intra-crystalline proteins, possibly resulting from the greater stability of calcite. These features allow greater temporal resolution and an extension of the dating range beyond the early Middle Pleistocene. Here we provide full details of the analyses for 480 samples from 100 horizons (75 sites), ranging from Late Pliocene to modern. These show that the dating technique is applicable to the entire Quaternary. Data are provided from all the stratotypes from British stages to have yielded opercula, which are shown to be clearly separable using this revised method. Further checks on the data are provided by reference to other type-sites for different stages (including some not formally defined). Additional tests are provided by sites with independent geochronology, or which can be associated with a terrace stratigraphy or biostratigraphy. This new aminostratigraphy for the non-marine Quaternary deposits of southern Britain provides a framework for understanding the regional geological and archaeological record. Comparison with reference to sites yielding independent geochronology, in combination with other lines of evidence, allows tentative correlation with the marine oxygen isotope record. PMID:23396683

  20. Quaternary geochronology and distribution of Mammuthus on the Colorado Plateau

    NASA Astrophysics Data System (ADS)

    Agenbroad, Larry D.; Mead, Jim I.

    1989-09-01

    There are 41 known localities containing mammoth remains from the Colorado Plateau: 24 in Arizona, 12 in Utah, 3 in New Mexico, and 2 in Colorado. Of the 41 localities, 13 (32%; Arizona and Utah only) have yielded radiometric dates (14C and U/Th); 10 (77%) of these have been the result of our investigations. The four youngest radiocarbon dates produce a weighted average date of approximately 11,270 ±65 yr B.P., the youngest directly aged mammoth remains on the Colorado Plateau. Mammoth remains are recovered predominantly in alluvial regimes, in addition to alcove, cave, and spring deposits. No direct association of Mammuthus and the Clovis hunters has been reported from the Colorado Plateau. Dietary intake, recorded in dung remains, included predominantly graminoids, in addition to various woody shrubs and trees that currently grow at higher elevations on the Colorado Plateau.

  1. Quaternary geochronology and distribution of Mammuthus on the Colorado Plateau

    SciTech Connect

    Agenbroad, L.D.; Mead, J.I. (Northern Arizona Univ., Flagstaff (USA))

    1989-09-01

    There are 41 known localities containing mammoth remains from the Colorado Plateau: 24 in Arizona, 12 in Utah, 3 in New Mexico, and 2 in Colorado. Of the 41 localities, 13 (32%; Arizona and Utah only) have yielded radiometric dates ({sup 14}C and U/Th); 10 (77%) of these have been the result of the authors' investigations. The four youngest radiocarbon dates produce a weighted average date of approximately 11,270 {plus minus}65 yr B.P., the youngest directly aged mammoth remains on the Colorado Plateau. Mammoth remains are recovered predominantly in alluvial regimes, in addition to alcove, cave, and spring deposits. No direct association of Mammuthus and the Clovis hunters has been reported from the Colorado Plateau. Dietary intake, recorded in dung remains, included predominantly graminoids, in addition to various woody shrubs and trees that currently grow at higher elevations on the Colorado Plateau.

  2. A combined hydrochemical - isotopic approach for assessing the regional pollution of an alluvial aquifer in a urbanized environment

    NASA Astrophysics Data System (ADS)

    Gesels, Julie; Orban, Philippe; Popescu, Cristina; Knöller, Kay; Brouyère, Serge

    2014-05-01

    The alluvial aquifer of the Meuse River is contaminated at regional scale in the urbanized and industrialized area of Liège in Belgium with different types of contaminants, in particular inorganics such as sulfate, nitrate and ammonium. The sources of those contaminants are numerous: brownfields, urban waste water, subsurface acid mine drainage from former coal mines, atmospheric deposits related to pollutants emissions in the atmosphere... Sulfate, nitrate and ammonium are both typical pollutants of the aquifer and tracers of the possible pollution sources. According to the European legislation on water, groundwater resources should reach a good quality status before 2015. However, an exemption can be obtained if it may be unfeasible or unreasonably expensive to achieve good status. In this case, groundwater quality objectives and management plans can be adapted to these specific conditions. To obtain such an exemption for the Meuse alluvial aquifer, it is required to demonstrate that the poor qualitative status is caused by acid mine drainage, or by widespread historical atmospheric deposition from industries, and not by recent anthropogenic contamination from the urban and industrial context. In this context, a detailed hydrogeochemical characterization of groundwater has been performed, with the aim of determining the origin of the inorganic contaminations and the main processes contributing to poor groundwater quality. A large hydrochemical sampling campaign was performed, based on 71 selected representative sampling locations, to better characterize the different vectors (end-members) of contamination of the alluvial aquifer and their respective contribution to groundwater contamination in the area. Groundwater samples were collected and analyzed for major and minor compounds and metallic trace elements. The analyses also include stable isotopes in water, sulfate, nitrate, ammonium, boron and strontium. Different hydrogeochemical approaches are combined to obtain a global understanding of the hydrogeochemical processes at regional scale. Hydrochemical interpretations are based on classical diagrams (e.g. Piper), spatial distribution maps, geochemical equations, multivariate statistics and isotopic analyses. With this combined approach, the location of the contaminant sources and most contaminated sectors of the alluvial aquifer together with a better understanding of geochemical processes involved are obtained.

  3. Evidence for episodic alluvial fan formation in far western Terra Tyrrhena, Mars

    NASA Astrophysics Data System (ADS)

    Williams, Rebecca M. E.; Deanne Rogers, A.; Chojnacki, Matthew; Boyce, Joseph; Seelos, Kimberly D.; Hardgrove, Craig; Chuang, Frank

    2011-01-01

    A Late Noachian-aged alluvial fan complex within Harris Crater in far western Terra Tyrrhena, Mars, is comprised of two well-defined source regions and associated discrete depositional lobes. Three fan units were recognized based on common morphological characteristics, thermal properties and spectral signatures. Although the entire fan complex has been subjected to extensive erosional degradation, the preserved morphologies record episodic fan formation and indicate the type of flow processes that occurred; the bulk of the fan surface has morphology consistent with fluvial emplacement while one fan unit exhibits a rugged surface texture with boulders consistent with a debris flow. This transition from fluvial to late-stage debris flow(s) suggests a decline in available water and/or change in sediment supply. The thermal inertia values obtained for all three fan surface units (mean values ranged from 318 to 344 J m -2 K -1 s -1/2) are typical for coarse-grained and/or well-indurated materials on Mars, but subtle variations point to important distinctions. Variations in aeolian bedform coverage as well as the density of ridges (inferred inverted channels) and boulders contribute to these subtle fan thermophysical differences and likely reflect changes in the fan depositional mechanisms and variations in post-depositional modification histories. The majority of the alluvial fan surface has a spectral signature that is broadly similar to TES "Surface Type 2" (ST2), with some important exceptions at long wavelengths. However, a unique spectral component was identified in one of the fan units (unit 3), that likely reflects lithological differences from other fan materials. This spectral attribute of unit 3 matched locations within the western catchment providing confirmation of provenance and supporting the contention that sediment supply changed over time as the fan developed. Finally, we applied simple modeling to a well preserved subsection of the fan complex to quantify the developmental history. Using the computed eastern fan volume (32 km 3), significant water, likely from precipitation, was involved in fan construction (>50 km 3) and an extensive period of fan formation occurred over millennia or longer.

  4. Rates of pedogenesis and influences of climatic change on soil development during the Quaternary

    SciTech Connect

    McFadden, L.D.

    1985-01-01

    Soils are natural systems that are complexly related to the influences of several independent and often interdependent variables; however, Jenny's factorial approach (1941) provides a strategy to evaluate the impact of only one or two of these variables on pedogenesis. In suites of Quaternary surficial deposits, locally favorable circumstances permit study of soil formation as functions of age and climatic changes. Soil chronosequence studies in climates ranging from currently very arid to subhumid demonstrate that soil age and profile development are strongly related. Soil profile indices that quantify changes in soil morphology, and chemical and mineralogic studies of soils provide data that enable correlations of Quaternary surficial deposits over large regions as well as providing relative and numerical age data of soil. Significant changes in climate during the Quaternary provide a unique opportunity to evaluate the impact of climatic changes on patterns of soil development. The depth of carbonate and soluble salts illuviation and the composition of iron oxides are quite sensitive to changes in the soil-temperature and leaching regime. Modeling studies indicate that: (1) changes in the depth of carbonate and clay illuviation are compatible with climatic change-induced variation in soil moisture regimes and (2) climatic change-induced temporal variation in dust flux and composition have significantly influenced the rates, processes and magnitude of soil development during the Quaternary.

  5. Pliocene-Pleistocene continental deposits in western Kentucky: A new look at regional stratigraphy and depositional history

    SciTech Connect

    Phillips, B.E. (Martin Marietta Energy Systems, Inc., Paducah, KY (United States))

    1992-01-01

    Pliocene and Pleistocene age sediments of the northernmost Mississippi Embayment consist of a thick sequence of continental deposits which rest unconformably on Cretaceous through Eocene strata. The continental deposits have been tentatively correlated to the Pliocene Mounds Gravel and Pleistocene Henry and Equality Formations of southern Illinois. These sediments have previously been interpreted as representing alluvial fan and fluvial deposits. The continental deposits are generally divided into three lithofacies: (1) silt/clay dominated; (2) sand dominated, and (3) gravel dominated. A subsurface study utilizing approximately 300 soil borings has shown that (1) the continental deposits, particularly the gravel facies, exhibit significant local changes in thickness, (2) the upper portion of the sequence consists predominantly of finer-grained silt/clay lithofacies, and (3) sand and gravel lithofacies within the upper sequence often occur at predictable horizons. These observations indicate a paleovalley fill with distinct depositional episodes. As a result of Pleistocene base level fluctuations, stream systems became deeply entrenched in the Pliocene alluvial fan and older sediments. Fan deposits were initially transported and redeposited in a braided fluvial system. As valley alluviation continued and gradients decreased, the braided fluvial system evolved into a meandering system. During Woodfordian time, slackwater lakes created by glacial outwash dams produced extensive lacustrine deposits. At least two major episodes of lacustrine sedimentation are apparent. Significant fluctuations of lake level are recognized in the subsurface by local erosional surfaces overlain by coarser-grained sediments deposited in basinward-migrating channel and shoreline facies.

  6. Paleomagnetic data of the loess-soil deposits by the example of the cut Arkutsay in the Chirchik river basin of Uzbekistan

    NASA Astrophysics Data System (ADS)

    Khusainov, K.; Toychiev, H. A.; Stelmakh, A. G.; Sultonov, S.

    2011-12-01

    In the basin of the river Chirchik loess-soil deposits are widespread and are represented different by lithology and genesis of deposits. As deposits are lithologically loess-like loams, gravels, sands and sandy loams. On the genesis of deposits are alluvial, proluvial, deluvial and lacustrine deposits. Arkutsay cut located on the southern slope of the ridge of Karzhantau and most fully reflects the paleomagnetism loess deposits of Quaternary period. Here from landslide were opened the horizons loess-soil deposits with a total capacity of more than 70 meters. Loess-soil deposits lie with unconformity on the Neogene sediments. In the studied section were installed 19 paleosoils. In general, for the paleomagnetic and magnetic studies have been selected the 3360 samples as blocks. Samples were collected continuously prior to depth 50 meters and with intervals in 0.1 meters from depth 50 prior to 70 meters. In laboratory studies have established the value of the natural remanent magnetization the loess deposits. Natural remanent magnetization of the samples that have directly magnetized varies (8.0/16.0)*10-6SGS and of the samples that have back magnetized varies (1.0/8.0)*10-6SGS. The magnetic susceptibility of loess deposits varies in the range (16.0/42.0)*10-6SGS with its average value is 30.0*10-6SGS. Natural remanent magnetization of the paleosoil varies (12.6/49.0)*10-6SGS with its average value is 24.2*10-6SGS, and the magnetic susceptibility of the paleosoil varies in the range (37.0/224.0)*10-6SGS with its average value is 73.5*10-6SGS. High values natural remanent magnetization and magnetic susceptibility are found in I, III, V, VII, VIII, IX and XI paleosoils. Paleomagnetic study of the cut Arkutsay determined that the loess-soil deposits from the top of the cut prior to depth 52 meters are magnetized in the direction of the modern geomagnetic field and there are three short-term return of the episode prior to depth 7 meters. In the lower part of the cut in the back magnetized sediments are three straight magnetized horizont at a depth from 50 meters prior to 70 meters.

  7. From source to sink in the sediment cascade of the Hei-River Basin: Implications for late Quaternary landscape dynamics in the Gobi Desert, NW China

    NASA Astrophysics Data System (ADS)

    Schimpf, Stefan; Nottebaum, Veit; Diekmann, Bernhard; Hartmann, Kai; Lehmkuhl, Frank; Wünnemann, Bernd; Zhang, Chi

    2014-05-01

    The Hei River Basin with a catchment size of ~130,000 km² is host to one of the largest continental alluvial fans in the world. The basin comprises: (1) its high-elevated river sources in the glacier and the permafrost zone of the Qilian Mountains, (2) the semi-arid foreland of the Hexi Corridor in the middle reaches and (3) the endorheic Ejina Basin (Gaxun Nur Basin) as its recent sink. The river basin is characterized by small subcatchments of hyper-arid mountain ranges of the Gobi-Tienshan and Beishan as well as of smooth and fuzzy water divides of the Hexi-Corridor and the Badain Jaran Sand Sea. Up to 300 m of Quaternary sediments establish the large Ejina Basin, with a size of 28,000 km², as an excellent archive for environmental reconstructions located at the recent intersection of westerly and monsoonal air masses. Three sediment cores (up to 230 m long) provide evidence of sedimentation dynamics over the last 250,000 years, and cover at least two terminations since OIS 6. The sediments have to be regarded as a result of the interplay between tectonic activity and climate dynamics, accompanied by a related eolian and hydrological response of the catchment. Thus, it is crucial to understand and reconstruct the sedimentary processes along the huge sediment cascades, and to identify the most important sediment sources. Here we present a provenance analysis from mineralogical fingerprints of modern sediments that have been deposited along recent pathways from the sources to the Ejina Basin. The methodical approach combines the analysis of clay minerals, bulk mineralogy, and bulk geochemistry. Furthermore, we use heavy mineral data obtained from automated particle-analysis via a computer-controlled scanning electron microscope (CCSEM) and XRD measurements. We analyzed ~200 surface samples from the whole catchment as reference material, as well as the upper 19 m of cored sediments, to gain insight into temporal changes of depositional processes and provenance. Geostatistical analyses of the compositional data reveal a clear discrimination between sediments from the Qilian Shan in the south and from local basin sediments in the north. Moreover the mineralogical fingerprints allow the differentiation of sources from intrusive rocks that are dominant in the Bei Shan mountain sub-catchment, and from greenschist-bearing metamorphic rocks, that are widespread in the Qilian Mountain catchment. Finally, we draw conclusions about the main transport processes and pathways from assumed source regions to the sink (Ejina Basin). The provenance analysis of the sediment core reveals strong changes from local (Bei Shan) to long-distant (Qilian Shan) sources. The Late Pleistocene record reveals frequently changing sediment supply between periodic high mountain runoff and local episodic runoff. We assume that these variations are related to basin internal processes (e.g. fan dynamics, tectonics) and changing environmental conditions that are linked with variations in meltwater runoff and precipitation in the upper reaches of the southern catchment. These conclusions are supported by grain size characteristics that indicate phases of predominant alluvial activity and limnic deposition around the Late Glacial to Holocene transition and enhanced pre-Holocene eolian activity.

  8. Groundwater research in the alluvial of river Sitnica, Kosova

    NASA Astrophysics Data System (ADS)

    Avdullahi, S.; Fejza, I.; Osmani, L.

    2009-04-01

    In the today's world, the problems of too much, too little or too polluted water are increasing at a rapid rate. Water resources in Kosova are relatively small, the average of annual runoff is 3.61miliard m3, relatively 113m3/s. Territory of Kosova is divided in four river basins: Drini i Bardhë, Ibri, Morava e Binqës and Lepenci. Sitnica River belongs to the river basin Ibri. The total surface of in this river is 2.861km2, the average of the annual rainfalls is 686mm, from which around 93mm (13.6%) flows on the surface and around 593mm (84.6%) infiltrates. In this case study are applied different methods for groundwater research and calculations of hydro-geological parameters in the alluvial of river Sitnica. Geophysics researches carried out with geo-electrical sounding and geo-electrical profile line. The goal of the geophysics researches is to identify hydrogeological collector and to determine the best position for placement of the piezometers. The geophysics research are done in aquifer area, in which 10 profiles line with different lengths and placed in distance from 30 m between each other are done. After finishing of the geophysics works, seven drilling wells with general length from 95.5 m are completed. Based to the testing results of two drilling wells we have concluded that the quantity of 27.4(l/sec) water can be exploited. The achieved results from application of those methods in this case study show that alluvial of river Sitnica are rich with groundwater. Based to the statistics the population is increasing in Kosova also water needs will be increasing too, so it is necessary to explore the existing groundwater for improving drinking water supply, industrial waters, agriculture etc. Key works: river, alluvial, geophysics researches, drilling wells, hydrogeological collector, water

  9. Co-contamination of As and F in alluvial aquifer

    NASA Astrophysics Data System (ADS)

    Kim, S.; Kim, K.; Kim, B.; Zhu, W.; Lee, E.; Ko, K.

    2010-12-01

    Co-contamination of As and F is frequently observed in alluvial aquifers of many countries including Argentina, Mexico, China, and Pakistan. However, processes causing this phenomenon are still poorly understood. In arid or semi-arid areas, the aquifers are generally under oxidizing condition and As and F show a good correlation. In contrast, groundwaters under reducing condition generally show a poorer correlation. In this study, we explored the geochemical mechanisms causing the co-contamination of As and F and their poorer correlation in the reducing environment by investigating alluvial groundwaters of the Mankyeong River floodplain, Korea. For this study, we collected 72 groundwater samples from 42 shallow wells placed into the alluvial aquifer. Desorption experiments using soils collected from the study area were also performed. Groundwater chemistry data showed that waters are under strong reducing condition and the reductive dissolution of Fe oxides was the main process increasing As concentration in groundwaters. The co-contamination was also observed in the study area and F did not show a good correlation with As. F showed concentrations increasing with pH. Desorption experiments also showed the dependences of As and F on pH. The experiments using soils treated with Na citrate-NaHCO3-dithonite solution indicated that iron oxides were the main phases hosting both As and F in soils. In our study area, pH of groundwaters increases due to a series of reduction reactions, and which increased F concentration by desorption from iron oxides. This result suggests that sharing the same adsorption hosts and the pH increased by reduction reactions are the main reason for the co-occurrence of As and F in alluvial groundwater under reducing environments. The lack of correlation between As and F was derived by the precipitation of As as sulfides in sulfate reducing condition. However, the correlation could be much better in the oxidizing condition because As released from iron oxides by pH increase cannot be removed as sulfides.

  10. Antibacterial and Hemolytic Activities of Quaternary Pyridinium

    E-print Network

    Antibacterial and Hemolytic Activities of Quaternary Pyridinium Functionalized Polynorbornenesa] They found that polymers with higher cationic functionality had stronger antibacterial activity. Sepa- rately, it was shown that methacrylate based polymers with pendant pyridinium moieties exhibited antibacterial activity

  11. Quaternary fossil faunas from caves in Takaka Valley and on Takaka Hill, northwest Nelson, South Island, New Zealand

    Microsoft Academic Search

    T. H. Worthy; R. N. Holdaway

    1994-01-01

    The late Quaternary fossil vertebrate faunas from 43 caves in Oligocene limestones and Ordovician marbles in the Takaka Valley and on Takaka Hill, northwest Nelson, New Zealand, are described and discussed. Depositional environments are described and interpreted. Major sites, including Ngarua Cave, Hawkes Cave, Kairuru Cave, Hobsons Tomo, and Irvines Tomo are described in detail. Many sites on Takaka Hill

  12. Quaternary seismic stratigraphy of the North Sea Fan: glacially-fed gravity flow aprons, hemipelagic sediments, and large submarine slides

    Microsoft Academic Search

    Edward L. King; Hans Petter Sejrup; Haflidi Haflidason; Anders Elverhøi; Inge Aarseth

    1996-01-01

    Approximately 1000 km of high resolution sleeve-gun array transects on the North Sea Fan, located at the mouth of the Norwegian Channel, reveal three dominant styles of sedimentation within a thick (> 900 m) Quaternary sediment wedge comprising numerous sequences. These are interpreted as: terrigenous hemipelagic sedimentation, large scale translational slides, and aprons of glaciogenic debris flow deposits contributing to

  13. Reinterpreting Rotherslade, Gower Peninsula: Implications for Last Glacial ice limits and Quaternary stratigraphy of the British Isles

    Microsoft Academic Search

    John F. Hiemstra; Kenneth F. Rijsdijk; Richard A. Shakesby; D. McCaroll

    2009-01-01

    Rotherslade on the Gower Peninsula in south Wales has been viewed as a key site for the reconstruction of Quaternary depositional environments in the British Isles. Since the early 20th century, and certainly since the 1980s, the accepted view has been that Rotherslade is the most westerly location on the south Gower coast where there is in situ basal till

  14. Deformation of Quaternary strata and its relationship to crustal folds and faults, south-central Puget Lowland, Washington State

    Microsoft Academic Search

    Derek B. Booth; Kathy Goetz Troost; Jonathan T. Hagstrum

    2004-01-01

    Folded Quaternary deposits across the south-central Puget Lowland, an area just south of the Seattle fault that extends across the Seattle uplift and its boundary with the adjacent Tacoma basin, provide increased resolution of the character and rate of crustal deformation. They also constrain alternative, and partly incom- patible, views of crustal structure previously suggested by geo- physical investigations. Tectonic

  15. Sedimentology and climatic environment of alluvial fans in the martian Saheki crater and a comparison with terrestrial fans in the Atacama Desert

    NASA Astrophysics Data System (ADS)

    Morgan, A. M.; Howard, A. D.; Hobley, D. E. J.; Moore, J. M.; Dietrich, W. E.; Williams, R. M. E.; Burr, D. M.; Grant, J. A.; Wilson, S. A.; Matsubara, Y.

    2014-02-01

    The deflated surfaces of the alluvial fans in Saheki crater reveal the most detailed record of fan stratigraphy and evolution found, to date, on Mars. During deposition of at least the uppermost 100 m of fan deposits, discharges from the source basin consisted of channelized flows transporting sediment (which we infer to be primarily sand- and gravel-sized) as bedload coupled with extensive overbank mud-rich flows depositing planar beds of sand-sized or finer sediment. Flow events are inferred to have been of modest magnitude (probably less than ?60 m3/s), of short duration, and probably occupied only a few distributaries during any individual flow event. Occasional channel avulsions resulted in the distribution of sediment across the entire fan. A comparison with fine-grained alluvial fans in Chile’s Atacama Desert provides insights into the processes responsible for constructing the Saheki crater fans: sediment is deposited by channelized flows (transporting sand through boulder-sized material) and overbank mudflows (sand size and finer) and wind erosion leaves channels expressed in inverted topographic relief. The most likely source of water was snowmelt released after annual or epochal accumulation of snow in the headwater source basin on the interior crater rim during the Hesperian to Amazonian periods. We infer the Saheki fans to have been constructed by many hundreds of separate flow events, and accumulation of the necessary snow and release of meltwater may have required favorable orbital configurations or transient global warming.

  16. Initial Results on the Pliocene and Quaternary Evolution of the Western Arctic from the Deep Drilling in 2008/09 at Lake Elgygytgyn, Chukotka (Invited)

    NASA Astrophysics Data System (ADS)

    Melles, M.; Brigham-Grette, J.; Minyuk, P.; Koeberl, C.; El'Gygytgyn Scientific Party

    2010-12-01

    Lake Elgygytgyn, located 100 km to the north of the Arctic Circle (67°30' N, 172°05' E) in a crater of 18 km diameter, was formed 3.6 Ma ago by a meteorite impact event. From Oct. 2008 until May 2009 an ICDP drilling campaign was conducted at Lake Elgygytgyn, achieving its three major objectives. First, drilling from the ice cover in the lake center penetrated the entire, 315 m thick lake sediment succession in 170 m water depth. The sediments show no indications for hiatuses due to glaciation or desiccation. Hence, their temporal length and geologic significance is absolutely unprecedented, for the first time providing deep and widely continuous insights into the climatic and environmental evolution of the terrestrial Arctic since Pliocene times. This is particularly true for the lowermost 40 m and uppermost 140 m of the sequence, which were drilled with almost 100 % recovery and, using the chronological information we have available, likely reflect the initial lake stage during the Pliocene and the last ca. 2.8 Ma, respectively. In between, the quality of the record is restricted due to lower recovery as a consequence of technical problems and/or sequences of coarse sand and gravel interbedded with lacustrine mud. Second, a ca. 200 m thick, almost complete section of impact breccias was recovered underneath the lake sediments, consisting of a ca. 100 m thick suevite layer above broken and fractured volcanic basement rocks. Investigation of this core sequence promises new information concerning the Elgygytgyn impact event, including the composition and nature of the meteorite, the energy released, and the shock behavior of the volcanic basement rocks. Third, a 142 m long sequence was recovered from the permafrost deposits in the western lake catchment, only a few hundred meters from the lake shore. The core consists of gravelly and sandy alluvial fan deposits, which are continuously frozen and rich with ground ice. The sediment and ice composition promises to provide complementary information on the regional climatic history and lake-level fluctuations. Besides, a thermistor chain installed in the drill hole as part of the “Thermal State of Permafrost Network” of the International Permafrost Association will contribute to the understanding of the permafrost behavior in light of contemporary rapid change. Processing and subsampling of the drill cores commenced in autumn 2009 and will be completed by the end of 2010. The presentation will summarize the operational success of the drilling campaign and highlight the scientific results obtained so far based on the limited onsite and ongoing offsite core processing. Special attention will be put on the lake sediment record and its significance for climatic and environmental changes in the area during Pliocene and Quaternary times.

  17. Geomorphology and morphometric characteristics of alluvial fans, Guadalupe Mountains National Park and adjacent areas, west Texas and New Mexico 

    E-print Network

    Given, Jeffrey Lyle

    2004-09-30

    This study qualitatively and quantitatively analyzes the geomorphology of alluvial fans in the Guadalupe Mountains Region (GMR) of west Texas and south-central New Mexico. Morphometric data for 31 alluvial fans and drainage basins ha ve been...

  18. A. Reservoir Effects of Stream Channels DAM IMPACTS ON AND RESTORATION OF AN ALLUVIAL RIVER

    E-print Network

    Julien, Pierre Y.

    A. Reservoir Effects of Stream Channels DAM IMPACTS ON AND RESTORATION OF AN ALLUVIAL RIVER ­ RIO GRANDE, NEW MEXICO Gigi RICHARD1 and Pierre JULIEN2 ABSTRACT The impact of construction of dams and reservoirs on alluvial rivers extends both upstream and downstream of the dam. Downstream of dams, both

  19. Metamodel-based design of alluvial channels at incipient motion subjected to seepage

    Microsoft Academic Search

    Bimlesh Kumar; Gopu Sreenivasulu; Achanta Ramakrishna Rao

    2010-01-01

    The design of an alluvial channel affected by seepage requires information about five basic parameters: particle size, water depth, energy slope, seepage velocity, and average velocity. The conventional approach to predicting the incipient motion in an alluvial channel cannot be applied in the case of a channel affected by seepage. Metamodelling techniques are nowadays widely used in engineering design to

  20. Depositional environments and paleogeography of the Upper Miocene Wassuk Group, west-central Nevada

    USGS Publications Warehouse

    Golia, R.T.; Stewart, John H.

    1984-01-01

    Fluvial and lacustrine deposits of the Miocene Wassuk Group, exposed in Coal Valley, west-central Nevada, are divided into five lithofacies: (1) diatomite, claystone, siltstone, and carbonaceous siltstone deposited in a lake with paludal conditions at the margin; (2) upward-coarsening sequences of sandstone deposited on a delta and fan-delta; (3) channel-form sandstone deposited on a distal braided alluvial plain; (4) clast-supported conglomerate deposited on a proxial braided alluvial plain or distal alluvial fan; and (5) matrix-supported conglomerate deposited on a distal to middle alluvial fan. Petrographic analysis records an upsection change from a predominantly andesitic to a predominantly plutonic provenance. This change, combined with the overall upward-coarsening of the Wassuk Group and the great thickness (2400 m) of the sequence, suggests active uplift and rapid subsidence during deposition of the group. Facies relationships and paleocurrent directions indicate source areas to the south, southeast and west of Coal Valley. The Miocene Wassuk Group was deposited in an intra-arc basin with penecontemporaneous volcanism and tectonic activity. Syndepositional faulting at the southern margin of Coal Valley between 13 and 11 m.y. ago suggests an early episode of northeast-southwest extension prior to the onset of east-west basin and range extension. ?? 1984.

  1. Basement and climate controls on proximal depositional systems in continental settings

    Microsoft Academic Search

    D. Ventra

    2011-01-01

    This doctoral dissertation discusses the sedimentology and dynamics of selected, modern and ancient clastic depositional systems (alluvial fans and colluvial aprons) at continental basin margins. The focus on single depositional systems gave the opportunity to devote particular attention to sedimentary processes and interactions on the basis of detailed field observations. The recent emphasis on modelling, remote sensing and basin-scale analysis

  2. Ground-Water Resource Assessment in the Rio Grande de Manati Alluvial Plain, Rio Arriba Saliente Area, Puerto Rico

    USGS Publications Warehouse

    Torres-Gonzalez, Sigfredo; Gómez-Gómez, Fernando; Warne, Andrew G.

    2002-01-01

    The alluvial aquifer within a 160-acre area of the Rio Grande de Manati alluvial plain was investigated to evaluate its potential as a water-supply source for the Barrios Rio Arriba Saliente and Pugnado Afuera, municipio of Manati, Puerto Rico. Analysis of well boring samples and the results of electric resistivity surveys indicate that the average thickness of the unconsolidated alluvial deposits in the study area is about 100 to 110 feet. The alluvium is a mixture of sand and gravel, which generally has a porosity of 0.2 to 0.35. Short-duration pump tests in small-diameter piezometers indicate that the alluvial aquifer has a hydraulic conductivity of about 200 feet per day and a transmissivity of about 7,900 feet squared per day. Analyses of water levels in piezometers, combined with stage measurements at a series of surveyed reference points along the Rio Grande de Manati channel, indicate that the water-table gradient in the alluvial aquifer is about 0.001, and that ground-water flow is generally from south to north, in the general direction of river flow. The water-table data indicate that the Rio Grande de Manati is the principal source of ground-water recharge to the alluvial aquifer in the study area. Because base flow for the Rio Grande de Manati is usually greater than 44 cubic feet per second, a continuous withdrawal rate of 0.5 to 1.0 cubic foot per second (225 to 450 gallons per minute) from a production well is possible. Chemical analysis of a ground-water sample indicates that the alluvial aquifer water meets U.S. Environmental Protection Agency secondary standards for selected constituents. Bacteriological analysis of ground-water samples indicates that the ground water contains little or no fecal coliform or fecal streptococcus bacteria. Although long-term data from upstream of the study area indicate high levels of fecal coliform and fecal streptococcus prior to 1996, bacteriological analyses of Rio Grande de Manati water samples obtained during the present study indicate that fecal coliform and fecal streptococcus concentrations are within the standards for surface water intended for use (or with the potential for use) as a raw source of public water supply in Puerto Rico. If a production well were constructed in the study area, it would be located close to the river channel (within 500 to 800 feet). Pumping from the porous and permeable alluvial aquifer close to the river channel could substantially enhance recharge from the Rio Grande de Manati channel to the aquifer. Enhanced recharge could shorten travel times for ground water in the aquifer, which might not allow sufficient time to attenuate bacteria and viruses. Travel times for bacteria moving from the river channel to a hypothetical production well were estimated using the numerical transport model MODFLOW/MT3DMS with an uncalibrated model of the alluvial aquifer. The model assumes a well pumping at 1 cubic foot per second. The transport of particles from the river to the well is most sensitive to the porosity of the aquifer and the pumping rate of the well. Sensitivity analysis indicates that a decrease in pumpage will increase the time of travel for particles to move from the river to the pumping well. The model indicates that the leading edge of a plume would reach the production well in about 40 days assuming a porosity of 0.20, 60 days assuming a porosity of 0.275, and about 70 days assuming a porosity of 0.35. If the well were moved 50 feet further from the river, the leading edge of the plume would reach the well in about 50 days assuming a porosity of 0.20 and about 70 days assuming a porosity of 0.275. These estimates are considered worse case estimates because no decay rate was included in the simulation, and because the hypothetical well was located in the center of the alluvial plain rather than further eastward, away from the river channel.

  3. First Quaternary Fossil Record of Caecilians from a Mexican Archaeological Site

    NASA Astrophysics Data System (ADS)

    Wake, Thomas A.; Wake, Marvalee H.; Lesure, Richard G.

    1999-07-01

    A single vertebra from an Early Formative period archaeological site in coastal Chiapas, México, is identified as belonging to the amphibian Dermophis mexicanus (Duméril and Bibron) 1841 (Amphibia: Gymnophiona: Caeciliidae). The vertebra was recovered from deposits dated to approximately 1200-1350 B.C. The specimen represents the first Quaternary fossil record for gymnophiones. Its presence suggests the possible role of the species as a bioturbator. Its recovery is further evidence of the utility of fine-grained archaeological recovery techniques.

  4. Late Quaternary sedimentation on the Portuguese continental margin: climate-related processes and products

    Microsoft Academic Search

    J. H. Baas; J. Mienert; F. Abrantes; M. A. Prins

    1997-01-01

    The late Quaternary sedimentary history of the continental margin off Portugal was reconstructed from sediment gravity cores. Hemipelagic sedimentation (lithofacies A) was dominant during glacial times. It was interrupted periodically by deposition of shelf- and upper-slope-derived silty and sandy terrigenous material by dilute turbidity currents (lithofacies B and C), ice-rafted debris during distinct periods of breakdown of North Atlantic ice

  5. Tropical Rain Forest and Climate Dynamics of the Atlantic Lowland, Southern Brazil, during the Late Quaternary

    Microsoft Academic Search

    Hermann Behling; Raquel R. B. Negrelle

    2001-01-01

    Palynological analysis of a core from the Atlantic rain forest region in Brazil provides unprecedented insight into late Quaternary vegetational and climate dynamics within this southern tropical lowland. The 576-cm-long sediment core is from a former beach-ridge “valley,” located 3 km inland from the Atlantic Ocean. Radio-carbon dates suggest that sediment deposition began prior to 35,000 14C yr B.P. Between

  6. The rio caliente ignimbrite: Analysis of a compound intraplinian ignimbrite from a major late quaternary Mexican eruption

    Microsoft Academic Search

    J. V. Wright

    1981-01-01

    The Rio Caliente ignimbrite is a multi-flow unit orcompound ignimbrite formed during a major late Quaternary explosive rhyolitic eruption of La Primavera volcano, Mexico. The eruption\\u000a sequence of the ignimbrite is complex and it occurs between lower and upper plinian air-fall deposits. It is, therefore, anintraplinian ignimbrite. Air-fall layers, pyroclastic surge, mudflow and fluviatile reworked pumice deposits also occur interbedded

  7. Syntheses and mechanical properties of quaternary Cr-Mo-Si-N coatings by a hybrid coating system

    Microsoft Academic Search

    Seung Gyun Hong; Dong-Woo Shin; Kwang Ho Kim

    2008-01-01

    Quaternary Cr-Mo-Si-N coatings have been deposited on AISI D2 steel and Si wafers by a hybrid coating system of arc ion plating (AIP) and dc magnetron sputtering techniques. A Cr3Mo AIP target with the fixed arc current of 55A and Si sputtering target with the varying current of 0–1.4A were utilized in Ar\\/N2 mixed atmosphere during Cr-Mo-Si-N deposition. Microstructure characteristics

  8. Late Quaternary terrestrial vertebrate coprolites from New Zealand

    NASA Astrophysics Data System (ADS)

    Wood, Jamie R.; Wilmshurst, Janet M.

    2014-08-01

    Over the past decade, concerted efforts to find and study Late Quaternary terrestrial vertebrate coprolites in New Zealand have revealed new insights into the diets and ecologies of New Zealand's prehistoric birds. Here, we provide a broader review of the coprolites found in natural (non-archaeological) Late Quaternary deposits from New Zealand. We summarise the morphological diversity of the coprolites, and discuss the taphonomy of the sites in which they are found. Since the 1870s more than 2000 coprolites have been discovered from 30 localities, all restricted to the South Island. The distribution of coprolite localities appears to reflect the presence of geological and climatic factors that enhance the potential for coprolite preservation; coprolites require dry conditions for preservation, and have been found on the ground surface within drafting cave entrances and at shallow (<300 mm) depths beneath rock overhangs with a northerly aspect. We classify the coprolites into eleven morphotypes, each of which may represent a range of different bird and/or reptile species. A review of genetically identified specimens shows that coprolites of different bird species overlap in size and morphology, reinforcing the need for identifications to be based on ancient DNA analysis.

  9. Large to intermediate-scale aquifer heterogeneity in fine-grain dominated alluvial fans (Cenozoic As Pontes Basin, northwestern Spain): insight based on three-dimensional geostatistical reconstruction

    NASA Astrophysics Data System (ADS)

    Falivene, O.; Cabrera, L.; Sáez, A.

    2007-08-01

    Facies reconstructions are used in hydrogeology to improve the interpretation of aquifer permeability distribution. In the absence of sufficient data to define the heterogeneity due to geological processes, uncertainties in the distribution of aquifer hydrofacies and characteristics may appear. Geometric and geostatistical methods are used to understand and model aquifer hydrofacies distribution, providing models to improve comprehension and development of aquifers. However, these models require some input statistical parameters that can be difficult to infer from the study site. A three-dimensional reconstruction of a kilometer scale fine-grain dominated Cenozoic alluvial fan derived from more than 200 continuously cored, closely spaced, and regularly distributed wells is presented. The facies distributions were reconstructed using a genetic stratigraphic subdivision and a deterministic geostatistical algorithm. The reconstruction is only slightly affected by variations in the geostatistical input parameters because of the high-density data set. Analysis of the reconstruction allowed identification in the proximal to medial alluvial fan zones of several laterally extensive sand bodies with relatively higher permeability; these sand bodies were quantified in terms of volume, mean thickness, maximum area, and maximum equivalent diameter. These quantifications provide trends and geological scenarios for input statistical parameters to model aquifer systems in similar alluvial fan depositional settings.

  10. Ice Age refugia and Quaternary extinctions: An issue of Quaternary evolutionary palaeoecology

    NASA Astrophysics Data System (ADS)

    Stewart, John R.; Cooper, Alan

    2008-12-01

    Quaternary palaeoecology, as a discipline, involves the analysis of a large range of fossil organisms from the last ca. 2 million years. This paper considers the role that these Quaternary records can take in better understanding the evolution of those organisms. We also discuss the surprisingly low uptake of evolutionary biology in Quaternary palaeoecological studies. This leads us to encourage an advance on both these fronts with a greater degree of collaboration with phylogeographic and ancient DNA researchers. These discussions accompany a summary of a special issue of Quaternary Science Reviews representing the proceedings of the XVII INQUA held in Cairns Australia in 2007. This special issue includes papers on a wide variety of Quaternary evolutionary palaeoecological and population dynamic subjects including extinct Pacific Island palm trees, Beringian beetles, Scandinavian trees, and the effects on human and animal populations of an extraterrestrial impact event in the Late Glacial of North America.

  11. Documented quaternary climate change on the Colorado Plateau: 40,000 YR B.P.-present

    SciTech Connect

    Agenbroad, L.D.; Mead, J.I. [Northern Arizona Univ., Flagstaff, AZ (United States)

    1995-09-01

    Ten years of interdisciplinary research on the Colorado Plateau have produced numerous, complimentary data sets documenting environmental change over the past 40,000 years. Radiocarbon controlled chronologies allow the correlation of multiple data sets, providing an increasingly broad spectrum of environmental changes within this interval. Data sets include documentation of the presence of extinct fauna; discovery and analyses of dung deposits from extinct Pleistocene fauna; packrat midden studies; insect analyses; snail analyses; and alluvial chronologies. The results presented will be considered preliminary, as we have on-going field and laboratory studies.

  12. Controls of the water and sediment fluxes on alluvial fans morphology: theory and experiments

    NASA Astrophysics Data System (ADS)

    Guerit, Laure; Delorme, Pauline; Métivier, François; Lajeunesse, Eric; Devauchelle, Olivier; Barrier, Laurie

    2015-04-01

    Alluvial fans are major sedimentary bodies that make the transition between the reliefs in erosion and the sedimentary basins, where deposition occurs. Understanding their dynamics of formation and evolution is a great problem of sediment transport, which leads to a better understanding of the control exerted by the water and sediment fluxes on the fan morphology. At the cost of several simplifications, we propose a totally predictive model for one-dimensional fans composed by one grain size and built under laminar flow. In this simplified context, it is possible to propose a unique relationship between the water flux, the sediment flux, the grain size and the slope of the fan. The theory is validated by one-dimension experiments, performed with glass beads and glycerine: the fan grows quasi-statically and maintains its slope just above the threshold for sediment transport. In addition, at leading order, the sediment discharge only controls the velocity at which the fan grows. These main predictions are then successfully tested in two-dimensional experiments.

  13. Groundwater movement, recharge, and perchlorate occurrence in a faulted alluvial aquifer in California (USA)

    NASA Astrophysics Data System (ADS)

    Izbicki, John A.; Teague, Nicholas F.; Hatzinger, Paul B.; Böhlke, J. K.; Sturchio, Neil C.

    2015-05-01

    Perchlorate from military, industrial, and legacy agricultural sources is present within an alluvial aquifer in the Rialto-Colton groundwater subbasin, 80 km east of Los Angeles, California (USA). The area is extensively faulted, with water-level differences exceeding 60 m across parts of the Rialto-Colton Fault separating the Rialto-Colton and Chino groundwater subbasins. Coupled well-bore flow and depth-dependent water-quality data show decreases in well yield and changes in water chemistry and isotopic composition, reflecting changing aquifer properties and groundwater recharge sources with depth. Perchlorate movement through some wells under unpumped conditions from shallower to deeper layers underlying mapped plumes was as high as 13 kg/year. Water-level maps suggest potential groundwater movement across the Rialto-Colton Fault through an overlying perched aquifer. Upward flow through a well in the Chino subbasin near the Rialto-Colton Fault suggests potential groundwater movement across the fault through permeable layers within partly consolidated deposits at depth. Although potentially important locally, movement of groundwater from the Rialto-Colton subbasin has not resulted in widespread occurrence of perchlorate within the Chino subbasin. Nitrate and perchlorate concentrations at the water table, associated with legacy agricultural fertilizer use, may be underestimated by data from long-screened wells that mix water from different depths within the aquifer.

  14. Sustainable Water Use System of Artesian Water in Alluvial Fan

    NASA Astrophysics Data System (ADS)

    Kishi, K.; Tsujimura, M.; Tase, N.

    2013-12-01

    The traditional water use system, developed with the intelligence of the local residents, usually takes advantage of local natural resources and is considered as a sustainable system, because of its energy saving(only forces of nature). For this reason, such kind of water use system is also recommended in some strategic policies for the purpose of a symbiosis between nature and human society. Therefore, it is important to clarify the relationship between human activities and water use systems. This study aims to clarify the mechanism of traditional water use processes in alluvial fan, and in addition, to investigate the important factors which help forming a sustainable water use system from the aspects of natural conditions and human activities. The study area, an alluvial fan region named Adogawa, is located in Shiga Prefecture, Japan and is in the west of Biwa Lake which is the largest lake in Japan. In this alluvial region where the land use is mainly occupied by settlements and paddy fields, a groundwater flowing well system is called "kabata" according to local tradition. During field survey, we took samples of groundwater, river water and lake water as well as measured the potential head of groundwater. The results showed that the upper boundary of flowing water was approximately 88m amsl, which is basically the same as the results reported by Kishi and Kanno (1966). In study area, a rapid increase of water pumping for domestic water use and melting snow during last 50 years, even if the irrigation area has decreased about 30% since 1970, and this fact may cause a decrease in recharge rate to groundwater. However, the groundwater level didn't decline based on the observed results, which is probably contributed by some water conservancy projects on Biwa Lake which maintained the water level of the lake. All the water samples are characterized by Ca-HCO3 type and similar stable isotopic value of ?D and ?18O. Groundwater level in irrigation season is higher than that in non-irrigation season, which indicates that groundwater level is apparently influenced by surface water. Some communities and NPOs working in this area maintain the "kabata" and canal for environment conservation. There are many rules for the local residents when using the water resources. For example, the use of detergents is prohibited for "kabata" users. The residents living upstream also should think of other groundwater users downstream. For this reason, it can be considered that the "kabata" water use method contributed to a symbiosis between ecosystem and human activity The study area case showed that the traditional water use system is useful for forming a sustainable groundwater flowing well use system.

  15. Quaternary geologic map of Minnesota

    NASA Technical Reports Server (NTRS)

    Goebel, J. E.

    1977-01-01

    The Quaternary Geologic Map of Minnesota is a compilation based both on the unique characteristics of satellite imagery and on the results of previous field investigations, both published and unpublished. The use of satellite imagery has made possible the timely and economical construction of this map. LANDSAT imagery interpretation proved more useful than expected. Most of the geologic units could be identified by extrapolating from specific sites where the geology had been investigated into areas where little was known. The excellent geographic registry coupled with the multi-spectral record of these images served to identify places where the geologic materials responded to their ecological environment and where the ecology responded to the geologic materials. Units were well located on the map at the scale selected for the study. Contacts between till units could be placed with reasonable accuracy. The reference points that were used to project delineations between units (rivers, lakes, hills, roads and other features), which had not been accurately located on early maps, could be accurately located with the help of the imagery. The tonal and color contrasts, the patterns reflecting geologic change and the resolution of the images permitted focusing attention on features which could be represented at the final scale of the map without distraction by other interesting but site-specific details.

  16. Quaternary glaciation of Mount Everest

    NASA Astrophysics Data System (ADS)

    Owen, Lewis A.; Robinson, Ruth; Benn, Douglas I.; Finkel, Robert C.; Davis, Nicole K.; Yi, Chaolu; Putkonen, Jaakko; Li, Dewen; Murray, Andrew S.

    2009-07-01

    The Quaternary glacial history of the Rongbuk valley on the northern slopes of Mount Everest is examined using field mapping, geomorphic and sedimentological methods, and optically stimulated luminescence (OSL) and 10Be terrestrial cosmogenic nuclide (TCN) dating. Six major sets of moraines are present representing significant glacier advances or still-stands. These date to >330 ka (Tingri moraine), >41 ka (Dzakar moraine), 24-27 ka (Jilong moraine), 14-17 ka (Rongbuk moraine), 8-2 ka (Samdupo moraines) and ˜1.6 ka (Xarlungnama moraine), and each is assigned to a distinct glacial stage named after the moraine. The Samdupo glacial stage is subdivided into Samdupo I (6.8-7.7 ka) and Samdupo II (˜2.4 ka). Comparison with OSL and TCN defined ages on moraines on the southern slopes of Mount Everest in the Khumbu Himal show that glaciations across the Everest massif were broadly synchronous. However, unlike the Khumbu Himal, no early Holocene glacier advance is recognized in the Rongbuk valley. This suggests that the Khumbu Himal may have received increased monsoon precipitation in the early Holocene to help increase positive glacier mass balances, while the Rongbuk valley was too sheltered to receive monsoon moisture during this time and glaciers could not advance. Comparison of equilibrium-line altitude depressions for glacial stages across Mount Everest reveals asymmetric patterns of glacier retreat that likely reflects greater glacier sensitivity to climate change on the northern slopes, possibly due to precipitation starvation.

  17. The Sedimentology and Alluvial Architecture of a Fluvial Braid Bars: the influence of scale and variability

    NASA Astrophysics Data System (ADS)

    Parsons, Daniel; Ashworth, Phillip; Sambrook Smith, Gregory; Best, Jim; Lunt, Ian; Orfeo, Oscar

    2015-04-01

    The influence of flow regime and scale on the sedimentology of river systems is largely unquantified. This paper presents results from ~ 30 km of ground penetrating radar (GPR) data from a mid-channel bar in the sixth largest river in the world, the Río Paraná, Argentina. The GPR profiles, with depth of penetration up to 12 m below the bar surface, allow a detailed quantification of substrate sedimentology of a large sandy braid bar ~ 3 km long by ~ 1 km wide on a grid with a 200 to 400 m spacing. Two facies were found to dominate the sedimentary architecture of the bar. The principal facies (~ 83% of total facies) comprises trough and planar cross-strata related to the migration of dunes, with the thickness of the cross-strata decreasing towards the bar surface. The second significant facies (~ 15%) is high-angle (generally 10-20°) strata that typically form by accretion at the bar margins or bartail. Clay drapes (< 2%) and cross-bar channels (< 1%) are shown to constitute only a minor part of the deposits. The paper compares these Río Paraná GPR surveys with other GPR studies of sandy braid bars from a range of different size river, that include the South Saskatchewan, Wisconsin, and Jamuna rivers. The dominance of dune deposits is ubiquitous to all rivers, with each also possessing a significant proportion of large-scale high-angle strata. However, two differences were found to exist between the deposits of these rivers: (1) the compound-bar deposits of smaller rivers contained greater proportions of the fills of cross-bar channels, which suggests a potential role for discharge variability as a factor in shaping the alluvial architecture through its impact on the frequency of sediment reworking over the bar tops, and, (2) the thickness of large-scale, high-angle sets decreases with the age of the bar, which suggests that the deposits of older bars may provide more useful geometrical analogues for interpreting ancient successions, than smaller transient, or recent, bar forms that have undergone only limited modification. The paper discusses the issue of flow variability in terms of both scale and the influences of tropical monsoonal signals on the sedimentology of the world's largest river systems.

  18. Micropaleontologic record of Quaternary paleoenvironments in the Central Albemarle Embayment, North Carolina, U.S.A.

    USGS Publications Warehouse

    Culver, Stephen J.; Farrell, Kathleen M.; Mallinson, David J.; Willard, Debra A.; Horton, Benjamin P.; Riggs, Stanley R.; Thieler, E. Robert; Wehmiller, John F.; Parham, Peter; Snyder, Scott W.; Hillier, Caroline

    2011-01-01

    To understand the temporal and spatial variation of eustatic sea-level fluctuations, glacio-hydro-isostacy, tectonics, subsidence, geologic environments and sedimentation patterns for the Quaternary of a passive continental margin, a nearly complete stratigraphic record that is fully integrated with a three dimensional chronostratigraphic framework, and paleoenvironmental information are necessary. The Albemarle Embayment, a Cenozoic regional depositional basin in eastern North Carolina located on the southeast Atlantic coast of the USA, is an ideal setting to unravel these dynamic, interrelated processes.Micropaleontological data, coupled with sedimentologic, chronostratigraphic and seismic data provide the bases for detailed interpretations of paleoenvironmental evolution and paleoclimates in the 90. m thick Quaternary record of the Albemarle Embayment. The data presented here come from a transect of cores drilled through a barrier island complex in the central Albemarle Embayment. This area sits in a ramp-like setting between late Pleistocene incised valleys.The data document the episodic infilling of the Albemarle Embayment throughout the Quaternary as a series of transgressive-regressive (T-R) cycles, characterized by inner shelf, midshelf, and shoreface assemblages, that overlie remnants of fluvial to estuarine valley-fill. Barrier island and marginal marine deposits have a low preservation potential. Inner to mid-shelf deposits of the early Pleistocene are overlain by similar middle Pleistocene shelf sediments in the south of the study area but entirely by inner shelf deposits in the north. Late Pleistocene marine sediments are of inner shelf origin and Holocene deposits are marginal marine in nature. Pleistocene marine sediments are incised, particularly in the northern half of the embayment by lowstand paleovalleys, partly filled by fluvial/floodplain deposits and in some cases, overlain by remnants of transgressive estuarine sediments. The shallowing through time of Quaternary sediments reflects the eastward progradational geometry of the continental shelf.The preservation potential of marginal marine deposits (barrier island, shoreface, backbarrier deposits) is not high, except in topographic lows associated with late Pleistocene paleovalleys and inlets because the current interglacial highstand has not yet reached its highest level. Given the documented increase in rate of relative sea-level rise in this region, shallow marine conditions are likely to return to the central Albemarle Embayment in the near future. ?? 2011 Elsevier B.V.

  19. Band reporting rates of mallards in the Mississippi alluvial valley

    USGS Publications Warehouse

    Reinecke, K.J.; Shaiffer, C.W.; Delnicki, D.

    1992-01-01

    We captured 2,182 mallards (Anas platyrhynchos) in eastcentral Arkansas and marked 730 with standard bands, 728 with 10 reward bands, and 724 with 'dummy' radio transmitters during November 1986-89 to estimate band reporting rates in the Mississippi Alluvial Valley (MAV). Assuming all transmitters were reported, reporting rates were 0.16 (SE=0.049) for standard bands and 0.34 (SE=0.081) for 10 reward bands. Interviews with hunters indicated that flock size distributions differed (P=0.03) between mallards wearing transmitters and those wearing bands (standard or reward). Mallards wearing transmitters were more likely to be alone and less likely to be in large flocks when recovered than were mallards wearing bands. These results suggest that either band reporting rates of mallards in the MAV are substantially less than those of midcontinent mallards (P=0.03), or marking mallards with external transmitters increases susceptibility to hunting mortality.

  20. Seismic Response of Alluvial Valleys to SH Waves

    SciTech Connect

    Ausilio, Ernesto; Conte, Enrico; Dente, Giovanni [Dipartimento di Difesa del Suolo, Universit della Calabria (Italy)

    2008-07-08

    This paper presents a theoretical study on the seismic response of alluvial valleys. The considered model consists of a two-dimensional elastic inclusion of arbitrary shape embedded in a stiffer half-plane excited by vertically or obliquely incident SH waves. Computations are conducted using a procedure based on the boundary element method. As known, this numerical technique is well suited to deal with wave propagation in infinite media as it avoids the introduction of fictitious boundaries and reduces by one the dimensions of the problem. This provides significant advantages from a computational point of view. A one-dimensional closed form solution is also used for comparison, and the most significant differences between the results obtained using the two methods are highlighted.

  1. Methodologies for hydraulic hazard mapping in alluvial fan areas

    NASA Astrophysics Data System (ADS)

    Milanesi, L.; Pilotti, M.; Ranzi, R.; Valerio, G.

    2014-09-01

    Hydraulic hazards in alluvial fan areas are mainly related to torrential floods and debris flows. These processes are characterized by their fast time evolution and relevant sediment load. Rational approaches for the estimation of hazard levels in flood-prone areas make use of the maps of depth and velocity, which are provided by numerical simulations of the event. This paper focuses on national regulations regarding quantitative debris-flow hazard mapping and compares them to a simple conceptual model for the quantification of the hazard levels on the basis of human stability in a flood. In particular, the proposed method takes into account, in a conceptual fashion, both the local slope and the density of the fluid, that are crucial aspects affecting stability for processes in mountain environments. Physically-based hazard criteria provide more comprehensible and objective maps, increasing awareness among stakeholders and providing more acceptable constraints for land planning.

  2. The measurement of total sediment load in alluvial streams

    USGS Publications Warehouse

    Benedict, P.C.; Matejka, D.Q.

    1953-01-01

    The measurement of the total sediment load transported by streams that flow in alluvial channels has been a perplexing problem to engineers and geologists for over a century. Until the last decade the development of equipment to measure bed load and suspended load was carried on almost independently, and without primary consideration of the fundamental laws governing the transportation of fluvial sediments. French investigators during the nineteenth century described methods of measurement and a mathematical approach for computing the rate of bed-load movement. The comprehensive laboratory investigations by Gilbert early in this century provided data that are still being used for studies of sediment transport. Detailed laboratory investigations of bed-load movement conducted during the last two decades by a number of investigators have resulted in the development of additional mathematical formulas for computing rates of bed-load movement. Likewise, studies of turbulent flow have provided the turbulence suspension theory for suspended sediment as it is known today.

  3. 230Th/U dating of a late pleistocene alluvial fan along the southern san andreas fault

    USGS Publications Warehouse

    Fletcher, K.E.K.; Sharp, W.D.; Kendrick, K.J.; Behr, W.M.; Hudnut, K.W.; Hanks, T.C.

    2010-01-01

    U-series dating of pedogenic carbonate-clast coatings provides a reliable, precise minimum age of 45.1 ?? 0.6 ka (2??) for the T2 geomorphic surface of the Biskra Palms alluvial fan, Coachella Valley, California. Concordant ages for multiple subsamples from individual carbonate coatings provide evidence that the 238U-234U-230Th system has remained closed since carbonate formation. The U-series minimum age is used to assess previously published 10Be exposure ages of cobbles and boulders. All but one cobble age and some boulder 10Be ages are younger than the U-series minimum age, indicating that surface cobbles and some boulders were partially shielded after deposition of the fan and have been subsequently exhumed by erosion of fine-grained matrix to expose them on the present fan surface. A comparison of U-series and 10Be ages indicates that the interval between final alluvial deposition on the T2 fan surface and accumulation of dateable carbonate is not well resolved at Biskra Palms; however, the "time lag" inherent to dating via U-series on pedogenic carbonate can be no larger than ~10 k.y., the uncertainty of the 10Be-derived age of the T2 fan surface. Dating of the T2 fan surface via U-series on pedogenic carbonate (minimum age, 45.1 ?? 0.6 ka) and 10Be on boulder-top samples using forward modeling (preferred age, 50 ?? 5 ka) provides broadly consistent constraints on the age of the fan surface and helps to elucidate its postdepositional development. ?? 2010 Geological Society of America.

  4. Late Quaternary Compression Revealed By Surface Faults At The Western Margin of Corsica Basin (corse, France)

    NASA Astrophysics Data System (ADS)

    Fellin, M. G.; Picotti, V.; Zattin, M.

    Corsica is a continental block located between the Ligurian-Balearic and the North Tyrrhenian Seas (Corsica basin). Recent studies indicate that from Eocene to Pliocene the structural evolution of Corsica was controlled by extensional tectonics which prob- ably continued till Holocene (Jolivet et al., 1998). New field data have been collected in the the Marana plain (Eastern Corsica), which is a subsiding area covered by allu- vial deposits. These deposits have been dated as late Quaternary by Conchon (1978) through outcrop analyses, wells, paleosoils and weathering rinds. The master fault, separating the Marana plain from the mountain range to the west, shows an extensional tectonics and a later compressional reactivation. The river network in the Marana plain area is characterized by incised meanders formed at the intersection between the rivers and the master fault. This feature is related to a river profile convexity and not to a lithological change of the bedrock. Therefore the incised meanders may be due to a recent activity of the master fault. Reverse faults cutting Wuermian deposits of the Marana plain have been observed for the first time and they indicate a late Quaternary NW-SE directed compression. This regime is in good agreement with the present day compressional stress field determined on the basis of earthquakes focal mechanism in the Ligurian Sea (Baroux et al., 2001) and it may be responsible for the reactivation of the master fault of the Marana plain. Conchon O., 1978: Quaternary studies in Corsica (France). Quaternary Research, v. 9, pp. 41-53. Jolivet L. et al., 1998: Midcrustal shear zones in postorogenic extension: ex- ample from the North Tyrrhenian Sea. J. Geoph. Res., v. 103 (B6), pp.12,123-12,160. Baroux E. et al., 2001: Analyses of the stress field in southern France from earthquakes focal mechanisms. Geophys. J. Int., v. 145, pp. 336-348.

  5. Nitrogen Transport in Thick, Unsaturated, Spatially Variable Alluvial Sediments

    NASA Astrophysics Data System (ADS)

    Denton, M. A.; Harter, T.; Hopmans, J. W.; Horwath, W. R.

    2001-12-01

    We are investigating the spatial variability of unsaturated hydraulic properties as part of an effort to improve our understanding of nitrogen transport through thick, unsaturated alluvial sediments that underlie many of the agricultural regions in the southwestern United States. Prior studies of soil nitrogen concentrations have focused on nitrogen cycling in the relatively shallow root zone and have generally not considered field-scale spatial variability of hydraulic properties. This study will survey nitrogen levels in a thick, layered, vadose zone at a well-controlled, long-term research nectarine orchard. The site is located in the Kings River alluvial fan on the east side of the San Joaquin Valley, approximately 30 miles southeast of Fresno, California, at the University of California Kearney Research Center. A controlled fertilizer experiment was conducted at the orchard over a 12-year period (1983-1994) during which three subplots were subjected to three different rates of fertilization: 0, 100, and 325 lbs/acre. During 1997-1998, we drilled and characterized approximately 3000 ft. of geologic material from 60 cores drilled to groundwater at a depth of 52 feet. Horizontal spacing of the borehole locations varied from 1.2 to 3 meters in a transect that is approximately 100 m long and 2.4 m wide. Nine major hydrofacies have been identified within the transect based on textural, morphological, and mineralogical interpretation of the continuous cores. Hydraulic properties of each of these hydrofacies are determined using the multi-step outflow method. Unsaturated hydraulic parameters for the van Genuchten and lognormal models are determined by inverse modeling of the multi-step outflow experiments. Armed with the hydraulic parameters the USGS numerical model VS2DT, modified to allow for the lognormal retention model, is used to model the fertilizer experiments. The results are compared to measured nitrate distributions in the subplots. This is the first step in developing a tool to assess the fate of nitrogen in deep, heterogeneous vadose zones.

  6. Anabranching Channel Patterns: the Kingdom of Large Alluvial Rivers

    NASA Astrophysics Data System (ADS)

    Latrubesse, Edgardo

    2015-04-01

    For a long time anabranching patterns were primarily restricted to "exotic and remote" zones in arid systems such as Australia. For that reason, they were not accepted as a major topic of discussion in our discipline, which was based on concepts principally derived from case studies in braided and meandering rivers of the Northern Hemisphere. However, anabranching alluvial patterns are widespread in a variety of environments and scales, from arid small rivers to alluvial reaches of giant rivers such as the Amazon, Congo, and Negro. The largest rivers of the world in water discharge are anabranching, and the majority of the forty-five largest rivers (water discharges >5000m3s-1) are dominantly anabranching systems. Only a small number of rivers with meandering patterns, or sinuous with branches (meandering-tendency to anabranch) are part of the largest rivers group. The present large anabranching rivers flowing on lowlands and well developed floodplains have in common a characteristic very slow slopes, specific stream power of < 25 Wm-2 and sandy bed load with sand sizes dominantly ranging from 0.1 < D50 <0.5 mm. The diversity of planforms and island morphologies in large anabranching rivers result from autogenic adjustments to millennial scales in broad valleys and to century-decadal scale channel-floodplain processes. The variety of anabranching styles are not specifically related to a single explanatory "physically based theory" but to a variety of morphological processes, complex-channel floodplain interactions and the geologic characteristics of the valleys. Once considered a kind of oddity, anabranching rivers must be considered major and fundamental representatives of the fluvial world.

  7. Reduction of Long-Term Bedrock Incision Efficiency by Short-Term Alluvial Cover Intermittency

    NASA Astrophysics Data System (ADS)

    Lague, D.

    2009-12-01

    Rapid mountain river incision through bedrock is an inherently stochastic process resulting from the long-term summation of flow and sediment discharge events at very variable rates and frequency. While the actual incision processes remains difficult to apprehend in situ and are the subject of ongoing research, there is no ambiguity on the inhibiting effect of a thick alluvial cover (several meters) on bed incision. This alluvial cover thickness strongly fluctuates as a function of stochastic supply of sediment by hillslopes, modulated by sediment transport and storage in the drainage network. Here, I study how this short-term stochasticity propagates into the long-term reduction of bedrock incision efficiency (the cover effect) at geological timescales, and how the upscaled cover model compare to existing empirical models. I introduce a new numerical model (SSTRIM, Stochastic Sediment Transport and River Incision Model) that resolves sediment transport and bedrock incision at daily timescales over a channel reach consisting of several trapezoidal cross-sections linked together. The model is run for thousands of years until a steady-state geometry is reached under the prevailing uplift, sediment supply and water discharge rates. The model incorporates (i) a stochastic sediment supply mimicking the pdf of sediment volume supplied by landsliding, (ii) a transport threshold and daily stochastic variations in water discharge, (iii) a freely evolving channel width and slope; (iv) an explicit treatment of alluvial thickness variations and corresponding bed incision reduction. Bed and bank incision are calculated as a function of bed and bank shear stress. Model results predict the existence of 2 cover dynamics regime: one in which the bed is almost permanently partially covered by sediment, and on in which intermittency dominates. In this later case, the cover effect operates over long-term by modulating the proportion of time where the channel is fully or not covered. Increased frequency of extreme events (sediment supply and/or flood) favors the intermittency regime. For boundary conditions typical of many mountain belts, the intermittent cover regime is expected to be the dominant mode of bed incision reduction in bedrock rivers. The long-term integrated cover effect law differs strongly from proposed theoretical and experimental models, and it is controlled by sediment supply stochasticity rather than the details of cover development at hydraulic timescale. Because of positive feedbacks between increased sediment supply, temporary deposition and transport capacity, it exhibits a much more non-linear variation with the ratio of sediment supply rate to transport capacity than the typical linear or exponential cover effect model. Model results also suggest that steady-state channel configuration always depends on sediment supply rate, while being never limited by transport capacity or strictly detachment-limited. These results point out that discharge and sediment supply stochasticity should be considered as important as the intricate details of incision laws operating at flood scale to model long-term bedrock channel dynamics.

  8. Quaternary morphotectonic mapping of the Wadi Araba and implications for the tectonic activity of the southern Dead Sea fault

    NASA Astrophysics Data System (ADS)

    Le BéOn, Maryline; Klinger, Yann; MéRiaux, Anne-Sophie; Al-Qaryouti, Mahmoud; Finkel, Robert C.; Mayyas, Omar; Tapponnier, Paul

    2012-10-01

    The Dead Sea strike-slip fault accommodates the northward motion of Arabia relative to Sinai at a rate of ˜5 mm/yr. The southern segment of the fault, the Wadi Araba fault, runs along a valley blanketed in Quaternary sediments. We first focused on understanding the relative and absolute timing of emplacement of the alluvial surfaces. We then determined the probable source of the sediments before assessing their lateral offset to constrain the late Pleistocene fault slip rate. Seven successive morphostratigraphic levels were identified. At two sites, we recognized an alluvial sequence of five to seven successive levels with ages getting younger northward, a pattern consistent with the western block moving southward relative to two fixed feeding channels located to the east. Surface samples were collected for10Be cosmogenic radionuclide dating. Fans F3 and F5 were found to be synchronous from site to site, at 102 ± 26 ka and 324 ± 22 ka, respectively, while F4 could be dated at 163 ± 19 ka at one site only. These are minimum ages, assuming no erosion of the alluvial surfaces. At least two of these periods are correlated with wet periods that are regionally well documented. Further analyses of tectonic offsets are affected in most cases by large uncertainties due to the configuration of the sites. They indicate maximum offsets of ˜5.5 km for the oldest, possibly ˜1 Ma old, surfaces. They lead to bracketing of the fault slip rate between 5 and 12 mm/yr, with preferred values of 5-7 mm/yr, for the last 300 ka.

  9. Bacterial adhesion inhibition of the quaternary ammonium functionalized silica nanoparticles

    Microsoft Academic Search

    Jooyoung Song; Hyeyoung Kong; Jyongsik Jang

    2011-01-01

    Quaternary ammonium compounds have been considered as excellent antibacterial agents due to their effective biocidal activity, long term durability and environmentally friendly performance. In this work, 3-(trimethoxysilyl)-propyldimethyloctadecylammonium chloride as a quaternary ammonium silane was applied for the surface modification of silica nanoparticles. The quaternary ammonium silane provided silica surface with hydrophobicity and antibacterial properties. In addition, the glass surface which

  10. Synthesis of Surface-Active Quaternary Amino Polyfluorosiloxanes

    E-print Network

    Chaudhury, Manoj K.

    , on further reaction with various amines followed by quaternization, gave quaternary amino polyfluorosiloxanes prepared by quaternization of fluorocarbon amines using alkyl halide. Quaternary fluorocarbon7 (CF3)2CF(CF2Synthesis of Surface-Active Quaternary Amino Polyfluorosiloxanes ASHISH VAIDYA, MANOJ CHAUDHURY

  11. Catalytic enantioselective synthesis of quaternary carbon stereocentres

    NASA Astrophysics Data System (ADS)

    Quasdorf, Kyle W.; Overman, Larry E.

    2014-12-01

    Quaternary carbon stereocentres--carbon atoms to which four distinct carbon substituents are attached--are common features of molecules found in nature. However, before recent advances in chemical catalysis, there were few methods of constructing single stereoisomers of this important structural motif. Here we discuss the many catalytic enantioselective reactions developed during the past decade for the synthesis of single stereoisomers of such organic molecules. This progress now makes it possible to incorporate quaternary stereocentres selectively in many organic molecules that are useful in medicine, agriculture and potentially other areas such as flavouring, fragrances and materials.

  12. Origin of Bermuda's clay-rich Quaternary paleosols and their paleoclimatic significance

    USGS Publications Warehouse

    Herwitz, S.R.; Muhs, D.R.; Prospero, J.M.; Mahan, S.; Vaughn, B.

    1996-01-01

    Red clayey paleosols that are chiefly the product of aerosolic dust deposition are interbedded in the Quaternary carbonate formations of the Bermuda oceanic island system. These paleosols provide a basis for reconstructing Quaternary atmospheric circulation patterns in the northwestern Atlantic. Geochemical analyses were performed on representative paleosol samples to identify their parent dust source. Fine-grained fractions were analyzed by energy-dispersive X ray fluorescence to determine trace element (Zr, Y, La, Ti, and Nb) concentrations and to derive geochemical signatures based on immobile element ratios. These ratios were compared with geochemical signatures determined for three possible sources of airborne dust: (1) Great Plains loess, (2) Mississippi River Valley loess, and (3) Saharan dust. The Zr/Y and Zr/La ratios provided the clearest distinction between the hypothesized dust sources. The low ratios in the paleosol B horizons most closely resemble Saharan dust in the <2-??m size class fraction. Contributions from the two North American loessial source areas could not be clearly detected. Thus Bermuda paleosols have a predominantly Saharan aerosolic dust signature. Saharan dust deposition on Bermuda during successive Quaternary glacial periods is consistent with patterns of general circulation models, which indicate that during glacial maxima the northeast summer trade winds were stronger than at present and reached latitudes higher than 30 ?? N despite lower-than-present sea surface temperatures in the North Atlantic.

  13. New perspectives on quaternary faulting in the southern Walker Lane, Nevada and California

    SciTech Connect

    Reheis, M.C.; Noller, J.S.

    1987-12-31

    A preliminary survey of aerial photographs of the southern Walker Lane began in late 1986. The purpose of this survey is to determine the nature and scope of future studies required to ascertain whether the apparent concentration of Quaternary faults in and near the Nevada Test Site is real or is simply a result of the greater effort invested in mapping Quaternary deposits in that area, and determine whether faults in the southern Walker Lane are active and could produce significant earthquakes. The survey is focused on the area extending south from Lone Mountain to Pahrump Valley and east from the Furnace Creek fault zone to an irregular line passing through the Cactus Range and Pahute Mesa. Lineaments and scraps were identified on stereopairs of black-and-white aerial photographs at scales of 1:80,000 or 1:60,000. The lineaments and and scarps were plotted on 1:24,000- and 1:62,500-scale topographic maps using a PG-2 plotter, and were color-coded according to distinctness and occurrence in Quaternary or Tertiary deposits (age assignments based on appearance in aerial photographs and on existing geologic maps). Additional lineaments identified on the topographic maps were also plotted. Areas of particular interest were selected for more detailed study using larger-scale aerial photographs. Most of the lineaments and scraps identified in the survey, although referred to as faults in this paper, have not been checked in the field. 11 refs., 1 fig.

  14. Sedimentation and depositional environments of the Barremian-Cenomanian Debre Libanose Sandstone, Blue Nile (Abay) Basin, Ethiopia

    Microsoft Academic Search

    A. Wolela

    2009-01-01

    Exploration of oil and gas deposits in the Blue Nile Basin targeted the Debre Libanose Sandstone as a reservoir objective. The unit was deposited in broad alluvial plains, and shows some elements of the Platte type braided river sedimentation in the lower and middle succession. The braided river sedimentation is dominated by single storey and multistorey amalgamated sandstone bodies, and

  15. Sedimentological control on the clay mineral distribution in the marine and non-marine Palaeogene deposits of Mallorca (Western Mediterranean)

    Microsoft Academic Search

    M. Ingles; E. Ramos-Guerrero

    1995-01-01

    During the Middle Eocene-Oligocene a marine and non-marine succession, about 1000 m thick, was deposited on Mallorca. Palaeoenvironmental interpretation of these deposits was obtained from sedimentological and palaeontological data in earlier studies.The non-marine environments recorded are: alluvial, fluvial (channel and flood plain deposits) and lacustrine (prevailing terrigenous, organic-rich or carbonate sedimentation). Marine environments are represented by littoral and shelf deposits.

  16. Quaternary geology of Vacherie salt dome, north Louisiana salt dome basin. Volume II

    SciTech Connect

    Kolb, C.R.; Holmes, J.C.; Alford, J.J.

    1983-07-01

    This volume comprises 14 appendices: lineations on Vacherie and Rayburn's domes (1977); possible geomorphic influence of Vacherie salt dome on the Quaternary fluvial geomorphology of Bashaway Creek (1980); remote sensing and analysis of radar imagery (1978); uphole seismic survey at Vacherie salt dome (1977); electrical resistivity survey at Vacherie salt dome (1978); pedologic investigations (1977); ionium-thorium dating of ironstones from terrace deposits, Vacherie salt dome, North Louisiana (1978); grain-shape and grain-surface studies (1981); the terrace concept - Gulf Coastal Plain (1981); interpretation of Quaternary sediments along lines of seismic shot hole (1976); topographic lows above domes (1977); structural significance of topographic lows above North Louisiana salt domes (1981); diagnostic microfossils - Vacherie dome (1978); and development of stratigraphy above Vacherie dome from Cretaceous to Sparta times (1982).

  17. Quaternary geologic map of the Ottawa 4 degrees x 6 degrees quadrangle, United States and Canada

    USGS Publications Warehouse

    Fullerton, David S.; Gadd, N. R., (compiler); Veillette, J.J.; Wagner, P.W.; Chapman, W.F.

    1993-01-01

    The Quaternary Geologic Map of the Ottawa 4 degree x 6 degree Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

  18. Engineering geologic feasibility of lignite mining in alluvial valleys by hydraulic dredging methods

    E-print Network

    Cason, Cynthia Lynn

    1982-01-01

    , or approximately a year's total production volume required for a single power plant boiler unit. This represents a considerable volume of potentially recoverable lignite. To the present, alluvial valleys have not been considered for mining purposes because...ENGINEERING GEOLOGIC FEASIBILITY OF LIGNITE MINING IN ALLUVIAL VALLEYS BY HYDRAULIC DREDGING METHODS A Thesis by CYNTHIA LYNN CASON Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement...

  19. Displacement rates on the Toroweap and Hurricane faults: implications for Quaternary downcutting in the Grand Canyon, Arizona

    USGS Publications Warehouse

    Fenton, Cassandra R.; Webb, Robert H.; Pearthree, Philip A.; Cerling, Thure E.; Poreda, Robert J.

    2001-01-01

    The Toroweap and Hurricane faults, considered to be the most active in Arizona, cross the Uinkaret volcanic field in the western Grand Canyon. These normal faults are downthrown to the west, and the Colorado River crosses these faults as it flows west in the Grand Canyon. Cosmogenic 3He (3Hec) dates on basalt flows and related landforms are used to calculate vertical displacement rates for these faults. The two faults cross unruptured alluvial fans dated as 3 ka (Toroweap) and 8 ka (Hurricane), and 10 other landforms that range in age from 30 to 400 ka are displaced. Middle and late Quaternary displacement rates of the Toroweap and Hurricane faults are 70–180 and 70–170 m/m.y., respectively. On the basis of these rates, the combined displacement of 580 m on these faults could have occurred in the past 3 to 5 m.y. All 3Hec dates are younger than existing K- Ar dates and are consistent with new 40Ar/39Ar dates and existing thermoluminescence (TL) dates on basalt flows. These different dating techniques may be combined in an analysis of displacement rates. Downcutting rates for the Colorado River in the eastern Grand Canyon (400 m/m.y.) are at least double the downcutting rates west of the faults (70–160 m/m.y.). Faulting probably increased downcutting in the eastern Grand Canyon relative to downcutting in the western Grand Canyon during the late Quaternary.

  20. Thermophysical Characterization of Terrestrial Alluvial Fans, With Applications to Mars

    NASA Astrophysics Data System (ADS)

    Moersch, J. E.; Whisner, S. C.; Hardgrove, C.

    2005-12-01

    Visible and infrared spectral remote sensing are currently being used to map lithologic variation on Mars, but these techniques are only sensitive to a depth equivalent to a few times the wavelength of observation (several 10's of microns at most). Thus, a fine regolith can make it difficult to characterize the geology of a surface based on spectral properties. This problem can be partially ameliorated by using thermal infrared temperature images. The temperature of the surface is controlled by material within approximately one diurnal thermal skin depth (typically a few cm) of the surface. Thermal images "see below" thin, spectrally obscuring surface layers, and enable the mapping of some underlying geologic heterogeneities (but not mineral compositions). Temperature variation is related, in part, to differences in thermal inertia, which in turn are related to lithology, particle size, degree of induration, and (for Earth) moisture content. THEMIS (and other) images of the Martian surface reveal a variety of features that may be the result of sedimentary processes. Earth analogs have been proposed for many of these features, but very little terrestrial analog work has been done to establish whether particular classes of sedimentary features have distinctive spatial-thermophysical signatures. Sedimentary processes often lead to sorting of grain sizes and/or varying degrees of cementation, so it is reasonable to expect that such signatures might exist. Here we present the results of a preliminary study of alluvial fans in Death Valley. As seen from above in ASTER nighttime thermal infrared images, these fans display distinct "thermophysical facies." Each fan apex has a relatively high thermal inertia, mid-fan areas have intermediate thermal inertias, and distal terminus areas have relatively low thermal inertias. This pattern of thermal inertias is consistent with field-based grain size studies that have been conducted on other debris flow-dominated fans in the area. We have also collected ground-based thermal images of one fan over a 24-hour insolation cycle in order to construct a "hypertemporal image cube" in which each spatial pixel contains a complete diurnal temperature curve. Principle component transformation of this unique data product allows us to separate the effects of surface geometry, shadows, and thermal inertia on surface temperatures. Our intent is to collect more such observations of alluvial fans and other sedimentary structures and compare them with nighttime THEMIS images of proposed analog structures on Mars.

  1. Magnetic properties of alluvial soils polluted with heavy metals

    NASA Astrophysics Data System (ADS)

    Dlouha, S.; Petrovsky, E.; Boruvka, L.; Kapicka, A.; Grison, H.

    2012-04-01

    Magnetic properties of soils, reflecting mineralogy, concentration and grain-size distribution of Fe-oxides, proved to be useful tool in assessing the soil properties in terms of various environmental conditions. Measurement of soil magnetic properties presents a convenient method to investigate the natural environmental changes in soils as well as the anthropogenic pollution of soils with several risk elements. The effect of fluvial pollution with Cd, Cu, Pb and Zn on magnetic soil properties was studied on highly contaminated alluvial soils from the mining/smelting district (P?íbram; CZ) using a combination of magnetic and geochemical methods. The basic soil characteristics, the content of heavy metals, oxalate, and dithionite extractable iron were determined in selected soil samples. Soil profiles were sampled using HUMAX soil corer and the magnetic susceptibility was measured in situ, further detailed magnetic analyses of selected distinct layers were carried out. Two types of variations of magnetic properties in soil profiles were observed corresponding to indentified soil types (Fluvisols, and Gleyic Fluvisols). Significantly higher values of topsoil magnetic susceptibility compared to underlying soil are accompanied with high concentration of heavy metals. Sequential extraction analysis proved the binding of Pb, Zn and Cd in Fe and Mn oxides. Concentration and size-dependent parameters (anhysteretic and isothermal magnetization) were measured on bulk samples in terms of assessing the origin of magnetic components. The results enabled to distinguish clearly topsoil layers enhanced with heavy metals from subsoil samples. The dominance of particles with pseudo-single domain behavior in topsoil and paramagnetic/antiferromagnetic contribution in subsoil were observed. These measurements were verified with room temperature hysteresis measurement carried out on bulk samples and magnetic extracts. Thermomagnetic analysis of magnetic susceptibility measured on magnetic extracts indicated the presence of magnetite/maghemite in the uppermost layers, and strong mineralogical transformation of iron oxyhydroxides during heating. Magnetic techniques give valuable information about the soil Fe oxides, which are useful for investigation of the environmental effects in soil. Key words: magnetic methods, Fe oxides, pollution, alluvial soils.

  2. Enantioselective construction of remote quaternary stereocentres

    NASA Astrophysics Data System (ADS)

    Mei, Tian-Sheng; Patel, Harshkumar H.; Sigman, Matthew S.

    2014-04-01

    Small molecules that contain all-carbon quaternary stereocentres--carbon atoms bonded to four distinct carbon substituents--are found in many secondary metabolites and some pharmaceutical agents. The construction of such compounds in an enantioselective fashion remains a long-standing challenge to synthetic organic chemists. In particular, methods for synthesizing quaternary stereocentres that are remote from other functional groups are underdeveloped. Here we report a catalytic and enantioselective intermolecular Heck-type reaction of trisubstituted-alkenyl alcohols with aryl boronic acids. This method provides direct access to quaternary all-carbon-substituted ?-, ?-, ?-, ?- or ?-aryl carbonyl compounds, because the unsaturation of the alkene is relayed to the alcohol, resulting in the formation of a carbonyl group. The scope of the process also includes incorporation of pre-existing stereocentres along the alkyl chain, which links the alkene and the alcohol, in which the stereocentre is preserved. The method described allows access to diverse molecular building blocks containing an enantiomerically enriched quaternary centre.

  3. Action of Quaternary Ammonium Salts on Nerve

    Microsoft Academic Search

    S. L. Cowan

    1933-01-01

    EXPERIMENTS similar to those of Fromherz with curare on medullated nerve, referred to by Prof. A. V. Hill in his article on ``The Physical Nature of the Nerve Impulse'',1 in NATURE of April 8, have been made with pure quaternary ammonium salts prepared by Dr. H. R. Ing. These have a curare-like action, preventing transmission of excitation from nerve to

  4. Method for clay stabilization with quaternary amines

    SciTech Connect

    Himes, R.E.

    1992-03-24

    This patent describes a method of treating a subterranean formation. It comprises: contacting the formation with an aqueous treatment fluid containing a formation control additive in an amount effective to stabilize the formation; the additive comprising a quaternary ammonium compound selected from compounds.

  5. Surface modification of sepiolite with quaternary amines

    Microsoft Academic Search

    Jovan Lemi?; Magdalena Tomaševi?-?anovi?; Mirjana Djuri?i?; Tanja Stani?

    2005-01-01

    This study was aimed at elucidating the mechanism of adsorption of quaternary amines, stearyldimethylbenzylammoniumchloride (SDBAC), as monomers and as micelles, distearyldimethylammoniumchloride (DDAC) and hexadecyltrimethylammoniumchloride (HTAC), on the surface of sepiolite. The adsorption capacity for these surfactants onto sepiolite, calculated by fitting the experimental data to the Langmuir–Freundlich equation, were 324% (SDBAC), 278% (DDAC), and 258% (HTAC) of the cation exchange

  6. ADSORPTION MECHANISM OF QUATERNARY AMINES BY SEPIOLITE

    Microsoft Academic Search

    E. Sabah; M. S. Çelik

    2002-01-01

    A series of adsorption tests examined the uptake of typical quaternary cationic surfactants, dodecyltrimethylammonium bromide and hexadecyltrimethylammonium bromide from water by a clay mineral, sepiolite. Adsorption tests conducted under different conditions revealed that sepiolite is highly receptive to adsorption of cationic surfactants. Adsorption of cationic surfactants on sepiolite exhibits two distinct regions. The first stage is characterized by low rate

  7. Connections between Quaternary and Binary Bent Functions

    E-print Network

    Connections between Quaternary and Binary Bent Functions Patrick Solâ??e 1 and Natalia Tokareva 2 1@math.nsc.ru Abstract. Boolean bent functions were introduced by Rothaus (1976) as combinatorial objects related to di functions (Schmidt, 2006) and quater­ nary bent functions (Kumar, Scholtz, Welch, 1985) are explored. We

  8. Connections between Quaternary and Binary Bent Functions

    E-print Network

    Tokareva, Natalia

    Connections between Quaternary and Binary Bent Functions Patrick Sol´e1 and Natalia Tokareva2 1@math.nsc.ru Abstract. Boolean bent functions were introduced by Rothaus (1976) as combinatorial objects related functions (Schmidt, 2006) and quater- nary bent functions (Kumar, Scholtz, Welch, 1985) are explored. We

  9. Asymmetric alluvial fans along strike-slip faults: A potential slip-rate record?

    NASA Astrophysics Data System (ADS)

    Morelan, A. E., III; Oskin, M. E.

    2014-12-01

    We investigate the phenomenon of asymmetric alluvial fan morphology along strike-slip faults. From analysis of high-resolution topographic data, we find that asymmetric alluvial fans are common along several strike-slip faults in the western United States. Affected fans are steeper in the direction of translation of the sediment source, often resulting in stream deflections counter to that expected from the sense of fault slip (e.g. left deflected streams along dextral faults). We hypothesize that fan asymmetry results from lateral translation of the sediment source relative to the depocenter. This relative motion changes the accommodation space in such a way that one side of the alluvial fan continuously progrades while the other is gradually abandoned. Therefore, lateral translation results in radial asymmetry of slopes about the fan apex. As a first approximation, we model this asymmetry as a result of diffusive sediment transport down fan. From this analysis, we predict that the degree of asymmetry of the alluvial fan is controlled by the ratio of sediment flux to fault slip rate. Qualitatively, more rapidly slipping faults should host more highly asymmetric fans; conversely, high sediment flux will obscure asymmetry. By measuring the sediment flux, through catchment-average concentration of cosmogenic isotopes or other means, we show that it is theoretically possible to quantify strike-slip fault slip-rates and alluvial-fan sediment transport rates using alluvial fan morphometry.

  10. Active tectonics and Quaternary basin formation along the Vienna Basin Transform fault

    NASA Astrophysics Data System (ADS)

    Decker, Kurt; Peresson, Herwig; Hinsch, Ralph

    2005-02-01

    The Vienna Basin Transform fault is an active fault system extending over a distance of some 300 km from the Eastern Alps through the Vienna Basin into the West Carpathians. Active sinistral movement is indicated by moderate seismic activity in a NE-striking zone paralleling the fault, focal plane solutions and recent stress measurements. By analogy to the Miocene kinematics we propose that the sinistral strike-slip fault terminates in the Carpathians where horizontal offset is transformed into thin-skinned thrust-type deformation. Hypocenter depths mostly well above 12 km are in line with the inferred thin-skinned style of deformation with active faults restricted to the overthrust Alpine-Carpathian units. Mapping of active fault segments in the Vienna Basin using subcrop data, thickness maps of Quaternary deposits, seismological data, and geomorphological features seen in the digital elevation model shows that virtually all active faults are reactivated Miocene structures. In the southern part of the basin active faulting defines a small-scale pull-apart structure with an actively subsiding Quaternary basin, which is filled with up to 140 m fluvial gravel, sand and paleosoils. For this basin Quaternary sinistral displacement was quantified by adopting a geometrical model for thin-skinned extensional strike-slip duplexes. Accordingly, 1.5-2 km sinistral slip accumulated during deposition of the basin fill in the last 400 ky corresponding to a slip rate of 1.6-2.5 mm/y. Results are in good agreement with published GPS data indicating 2 mm slip per year. A second group of Quaternary basins is related to listric normal faulting, rollover and crestal collapse of the reactivated normal faults at the NW basin margin. Rollover also resulted in tilting and dissecting Late Pleistocene river terraces of the Danube.

  11. Evidences for Neogene-Quaternary tectonics in Svalbard

    NASA Astrophysics Data System (ADS)

    Cianfarra, Paola; Salvini, Francesco

    2013-04-01

    Svalbard locates along the De Geer Transform Fault that separates the kinematics of North Atlantic and Arctic Ocean and are a continental rise along the North Atlantic portion of this transform. A fold and thrust belt of Paleogene age boards the Western margin of the Spitsbergen with a NNW-SSE trend. In the '60s the West - Spitsbergen fold and trust belt was related to the relative movements between Laurentia and Eurasia. Specifically, it was regarded to be a transpressive orogen developed at the intra-continental De Geer Transform margin between the Barents and the Greenland Shelves. This setting was suggested by the necessity of a continental transform off the western margin of Svalbard needed to restore the relative openings of the North Atlantic-Arctic Ocean basins, and the Paleogene age of the fold-belt. Later structural studies in other areas of Svalbard suggested that convergent tectonics have been prevailing during much of the fold and thrust development. However this belt can hardly be regarded as a classical orogen resulting from an active continental margin for the lack of evidence for subduction, synorogenic magmatism, metamorphism or a thickened crust. On the other hand, it would be difficult to merely relate this fold and thrust belt to the De Geer Transform Fault. According to Authors a transform fault should produce structures with vergence away from the fault on both sides, whereas the found direction of tectonic transport in North Greenland is the same as in Spitsbergen, i.e. to the E and NE. In this way the transform separation of North-Greenland and Spitsbergen should postdate the formation of the Tertiary North-Greenland and Spitsbergen fold and trust belt. This rises the question on possible Neogene-Quaternary tectonics in Spitsbergen. Evidence for this younger tectonics includes the occurrence of Quaternary volcanism and thermal springs in the northern part of Spitsbergen and the moderate seismicity in Nordaustlandet. Other clues supporting a recent tectonics derive from the analysis of satellite images and air photos, including the glacier and fluvial drainage suggesting a strong tectonic control. Moreover some authors have found in Ny Alesund an uplift rate from GPS measurements higher than those predicted by postglacial rebound models, again suggesting a tectonic contribution. Preliminary results from field work in the Brogger peninsula confirmed the presence of Neogene-Quaternary tectonics. Marine terraces and fluvio-glacial deposits show several N-S elongated steps along the northern projection of N-S trending faults cutting the Meso-Cenozoic rocks. N-S trending faults have been systematically found in Devonian to Tertiary rocks. These faults are characterised by right-lateral, strike-slip movements and the presence of near surface to sub aerial mineralizations on their surfaces, including kinematic indicators. N-S faults with the same kinematics show the presence of deformed Quaternary clastic, unconsolidated deposits within their shear zones. All the found brittle deformation evidence are compatible with the kinematics of the recent activity of the De Geer Transform Fault.

  12. An integrated approach to flood hazard assessment on alluvial fans using numerical modeling, field mapping, and remote sensing

    USGS Publications Warehouse

    Pelletier, J.D.; Mayer, L.; Pearthree, P.A.; House, P.K.; Demsey, K.A.; Klawon, J.K.; Vincent, K.R.

    2005-01-01

    Millions of people in the western United States live near the dynamic, distributary channel networks of alluvial fans where flood behavior is complex and poorly constrained. Here we test a new comprehensive approach to alluvial-fan flood hazard assessment that uses four complementary methods: two-dimensional raster-based hydraulic modeling, satellite-image change detection, fieldbased mapping of recent flood inundation, and surficial geologic mapping. Each of these methods provides spatial detail lacking in the standard method and each provides critical information for a comprehensive assessment. Our numerical model simultaneously solves the continuity equation and Manning's equation (Chow, 1959) using an implicit numerical method. It provides a robust numerical tool for predicting flood flows using the large, high-resolution Digital Elevation Models (DEMs) necessary to resolve the numerous small channels on the typical alluvial fan. Inundation extents and flow depths of historic floods can be reconstructed with the numerical model and validated against field- and satellite-based flood maps. A probabilistic flood hazard map can also be constructed by modeling multiple flood events with a range of specified discharges. This map can be used in conjunction with a surficial geologic map to further refine floodplain delineation on fans. To test the accuracy of the numerical model, we compared model predictions of flood inundation and flow depths against field- and satellite-based flood maps for two recent extreme events on the southern Tortolita and Harquahala piedmonts in Arizona. Model predictions match the field- and satellite-based maps closely. Probabilistic flood hazard maps based on the 10 yr, 100 yr, and maximum floods were also constructed for the study areas using stream gage records and paleoflood deposits. The resulting maps predict spatially complex flood hazards that strongly reflect small-scale topography and are consistent with surficial geology. In contrast, FEMA Flood Insurance Rate Maps (FIRMs) based on the FAN model predict uniformly high flood risk across the study areas without regard for small-scale topography and surficial geology. ?? 2005 Geological Society of America.

  13. Estimating the age of arid-zone alluvial fan surfaces using roughness measurements from spaceborne radar backscatter

    NASA Astrophysics Data System (ADS)

    Hetz, G.; Mushkin, A.; Blumberg, D. G.; Baer, G.; Trabelsky, E.

    2012-12-01

    Alluvial fan surfaces respond to geologic and climate changes as they record the deposition and erosion processes that govern their evolution, which amongst others is manifested in the micro and meso scale topography of the surface. Remote sensing provides a regional view that is very useful for mapping. Some previous publications have demonstrated that relative dating can also be achieved by remote sensing using techniques common in planetary geology such as overlap relationships. This work focuses on the use of radar backscatter as suggested originally by Evans et al., (1992) to map ages but here we will try to provide an absolute geologic age. The objective of this paper is to demonstrate the use of radar backscatter to constrain surface roughness as a calibrated proxy for estimating age of alluvial surfaces. With the unique regional spatial perspective provided by spaceborne imaging, we aim at providing a new and complementary regional perspective for studying neotectonic and recent landscape evolution processes as well as paleoclimate. Moreover, the method (by radar backscattering measure) can be applied to the geomorphology of other planets. The current study is located in the southeastern part of the Negev desert, Israel on the late Pleistocene - Holocene Shehoret alluvial fan sequence. High resolution (0.5 cm) 3D roughness measurements were collected using a ground-based LIDAR (Leica HDS 3000) and these show a robust relationship between independently obtained OSL surface age and surface roughness; the fan surfaces become smoother with time over 103-105 yr timescales. Spaceborne backscatter radar data respond primarily to surface slope, roughness at a scale comparable to the radar wavelength, and other parameters such as dielectric properties of the surface. Therefore, radar can provide a good quantitative indication of surface roughness in arid zones, where vegetation cover is low. Preliminary results show a relationship between surface age and roughness and the radar cross section extracted from polarimetric spaceborne data. The best result is found in cross polarization (HV), L-band measured at an incidence angle of 38°.

  14. Electrodeposition of iron-cobalt-nickel-copper quaternary system

    NASA Astrophysics Data System (ADS)

    Huang, Qiang

    Electrodeposition is a cost-effective method to produce thin film materials, which have been used widely in the microelectronic industry, and is advantageous to fabricate metal deposits into recessed and curved areas. In this dissertation, a FeCoNiCu quaternary alloy system was investigated, both experimentally and theoretically, for fabrication of multilayers, grating structures, and nanowires. Multilayer structures are composed of alternating ferromagnetic and nonmagnetic nanometric layers, and are of interest due to the giant magnetoresistance (GMR) property it possesses, a change in electric resistance in the presence of an external magnetic field. In addition, the compositional modulation, or the composition contrast, in multilayer structures can be used to develop a grating structured mold for the development of a novel nanoimprinting process. FeCoNiCu was investigated as a more general alloy system containing iron-group metals and a nonmagnetic element, Cu, which can be simplified and adapted to any binary or ternary systems. With a dilute tartrate sulfate bath nanometric multilayers were successfully fabricated with pulse plating and GMR value was reported for this electrodeposited system for the first time. A value of -6% was achieved on rotating disk electrode (RDE) and this maximum occurred when the structure had no preferred crystal phase. Over 40% GMR has been achieved when the multilayer was plated onto a polycrystalline Cu foil. A mathematical model was developed to tailor the deposition process on RDE, and both steady state and nonsteady state cases were simulated. A compositional gradient, which is inherent to a nonsteady state deposition process when the layer size is of nanometer scale was predicted. The quaternary system was explored for other applications. Selective etching of electrodeposited multilayer structures was investigated for different etching solutions. A diluted K2Cr2O 7/H2SO4 solution was successfully developed to produce grating structures for a nanoimprinting mold, which was demonstrated with a simple cast molding process. In addition, nanowire plating was explored with different plating schemes. Nanowires of multilayers were successfully fabricated, and the nanometric layer structure was verified. A deviation was observed in the layer thickness from DC plating, as a result of the nonsteady state plating process, consistent with the model developed.

  15. Quaternary incised valleys in southern Brazil coastal zone

    NASA Astrophysics Data System (ADS)

    Weschenfelder, Jair; Baitelli, Ricardo; Corrêa, Iran C. S.; Bortolin, Eduardo C.; dos Santos, Cristiane B.

    2014-11-01

    High-resolution seismic records obtained in the Rio Grande do Sul coastal zone, southern Brazil, revealed that prominent valleys and channels developed in the area before the installation of actual coastal plain. Landwards, the paleoincisions can be linked with the present courses of the main river dissecting the area. Oceanwards, they can be linked with related features previously recognized in the continental shelf and slope by means of seismic and morphostructural studies. Based mainly on seismic, core data and geologic reasoning, it can be inferred that the coastal valleys were incised during forced regression events into the coastal prism deposited during previous sea level highstand events of the Quaternary. Seismic data has revealed paleovalleys up to 10 km wide and, in some places, infilled with up to 40 m thick of sediments. The results indicated two distinct periods of cut-and-fill events in the Patos Lagoon area. The filling of the younger incision system is mainly Holocene and its onset is related to the last main regressive event of the Pleistocene, when the sea level fell about 130 m below the actual position. The older incision and filling event is related to the previous regressive-transgressive events of the Middle and Late Pleistocene. The fluvial discharge fed delta systems on the shelf edge during the sea level lowstands. The subsequent transgressions drowned the incised drainage, infilling it and closing the inlets formerly connecting the coastal river to the ocean. The incised features may have played a significant role on the basin-margin architecture, facies distribution and accommodation space during the multitude of up and down sea level events of the Quaternary.

  16. Biodegradation of Petroleum Hydrocarbon Vapors In Unsaturated Alluvial Sand

    NASA Astrophysics Data System (ADS)

    Höhener, P.; Duwig, C.; Pasteris, G.; Dakhel, N.; Kaufmann, K.; Werner, D.

    Biodegradation rates are critical parameters in models aimed at predicting the nat- ural attenuation of volatile organic compounds (VOCs) in the unsaturated zone. In this study the kinetic rate laws for the aerobic biodegradation of selected petroleum hydrocarbons and MTBE were investigated in unsaturated alluvial sand exposed to the vapors from a fuel mixture. Laboratory column and batch experiments were per- formed at room temperature under aerobic conditions. An analytical reactive transport model for VOC vapors in soil based on Monod kinetics is used for data interpretation. In the column experiment, steady-state diffusive vapor transport was reached after 23 days. Monod kinetic parameters were derived from the column profiles for toluene, m-xylene, octane and hexane. The degradation of cyclic alkanes, isooctane, and 1,2,4- trimethylbenzene was best described by first-order kinetics. MTBE, pentane and chlo- rofluorocarbons were recalcitrant. Batch experiments suggested first-order disappear- ance rate laws for all VOCs except octane, which followed zero-order kinetics. For some compounds including MTBE, disappearance rates in abiotic batch experiments were as high as in live batches. Abiotic disappearance is explained by slow intraparti- cle diffusion and sorption. It is concluded that the column approach is preferable for determining biodegradation rate parameters to be used in risk assessment models.

  17. Floodplain biogeochemical mosaics: A multidimensional view of alluvial soils

    NASA Astrophysics Data System (ADS)

    Appling, Alison P.; Bernhardt, Emily S.; Stanford, Jack A.

    2014-08-01

    The alluvial floodplains of large rivers are exceptionally productive and dynamic ecosystems, characterized by a complex mosaic of vegetation at different successional stages overlying soils sorted by historic floods. Natural floodplains are widely credited with efficiently removing nitrogen from surface waters and accumulating carbon in biomass, yet very little floodplain research has examined carbon and nitrogen cycling below surficial soils. We evaluated the extent to which vegetation cover could be used to predict subsurface carbon and nitrogen dynamics and to estimate whole-floodplain carbon storage and denitrification rates. We dug soil pits under three dominant vegetation communities on a gravel-bedded floodplain in northwest Montana to the depth of the permanent water table (1-3 m). We compared depth profiles of total and dissolved carbon (C) and nitrogen (N), denitrification potentials (DEAs), organic particulates, moisture, and pH across vegetation types. Near-surface soils (0-10 cm) of forests had larger C and N pools and DEAs than grasslands or gravel bars, but such vegetation effects dissipated within the upper ~50 cm of soil. At depth, spatial heterogeneity in carbon and nitrogen pools and fluxes depended instead on soil texture, and relatively high rates of DEA and carbon storage were measured in zones of buried organic debris. Although C storage and denitrification potential are generally low in subsurface soils, these deep soils might nonetheless contribute substantially to whole-floodplain C storage and denitrification because of their large volume, high hydrologic connectivity, and heterogeneous biogeochemistry.

  18. New constraints on the uplift history of the western Andes, north Chile, using cosmogenic He-3 in alluvial boulders

    NASA Astrophysics Data System (ADS)

    Evenstar, Laura; Stuart, Finlay; Hartley, Adrian

    2014-05-01

    To constrain mechanisms responsible for mountain belt growth independent methods for determining accurately the rate and timing of surface uplift are needed. Within the Central Andes paleoelevation proxies are afflicted by either large uncertainties or reliance on assumptions about past climate-elevation histories (Barnes and Ehmer. 2009). This leads to paleoelevation data being unable to distinguish between the two main uplift models of the Andes; gradual uplift of the Andes from the Late Eocene due to crustal shortening/thickening, and rapid uplift in the Late Miocene due to large-scale mantle delamination (Barnes and Ehmer. 2009). Here we present a new paleoelevation tool based on the varying production rate of in situ cosmogenic isotopes with elevation. It can constrain surface uplift histories independently of paleoclimatic fluctuations, making it potentially more accurate than previous methods. Within the Atacama Desert Northern Chile, a stable arid-hyperarid climate has persisted over the last 23 Ma (Dunai et al. 2005). This has lead to exceptionally low erosion rates and high cosmogenic nuclide concentrations within alluvial boulders overlying the Pacific Planation Surface (PPS). In the Aroma Quebrada region, the PPS can be constrained as forming post 13.4 Ma, using underlying volcanics (Evenstar 2007). Alluvial boulders that lie on this PPS have high concentrations of cosmogenic He-3 that suggest deposition soon after surface formation. Comparing concentrations of cosmogenic 3He in the boulders to those calculated for varying uplift histories the timing of the uplift of the western margin of the Andes can be constrained. The models require the Pacific Planation Surface to reach at least 2/3 of its current elevation by 13.4 Ma. These results are not consistent with rapid uplift of the Andes due to mantle delamination in the Late Miocene but support progressive shortening and thickening of continental crust initiating in the Early Miocene or earlier.

  19. Peclet number as affected by molecular diffusion controls transient anomalous transport in alluvial aquifer-aquitard complexes.

    PubMed

    Zhang, Yong; Green, Christopher T; Tick, Geoffrey R

    2015-01-01

    This study evaluates the role of the Peclet number as affected by molecular diffusion in transient anomalous transport, which is one of the major knowledge gaps in anomalous transport, by combining Monte Carlo simulations and stochastic model analysis. Two alluvial settings containing either short- or long-connected hydrofacies are generated and used as media for flow and transport modeling. Numerical experiments show that 1) the Peclet number affects both the duration of the power-law segment of tracer breakthrough curves (BTCs) and the transition rate from anomalous to Fickian transport by determining the solute residence time for a given low-permeability layer, 2) mechanical dispersion has a limited contribution to the anomalous characteristics of late-time transport as compared to molecular diffusion due to an almost negligible velocity in floodplain deposits, and 3) the initial source dimensions only enhance the power-law tail of the BTCs at short travel distances. A tempered stable stochastic (TSS) model is then applied to analyze the modeled transport. Applications show that the time-nonlocal parameters in the TSS model relate to the Peclet number, Pe. In particular, the truncation parameter in the TSS model increases nonlinearly with a decrease in Pe due to the decrease of the mean residence time, and the capacity coefficient increases with an increase in molecular diffusion which is probably due to the increase in the number of immobile particles. The above numerical experiments and stochastic analysis therefore reveal that the Peclet number as affected by molecular diffusion controls transient anomalous transport in alluvial aquifer-aquitard complexes. PMID:26001981

  20. Paleoecological inferences of recent alluvial damming of a lake basin due to retrogressive permafrost thaw slumping

    NASA Astrophysics Data System (ADS)

    Quinlan, R.; Delaney, S.; Lamoureux, S. F.; Kokelj, S. V.; Pisaric, M. F.

    2014-12-01

    Expected climate impacts of future warming in the Arctic include thawing of permafrost landscapes in northern latitudes. Thawing permafrost is expected to have major consequences on hydrological dynamics, which will affect the limnological conditions of Arctic lakes and ponds. In this study we obtained a sediment core from a small lake (informally named "FM1") near Fort McPherson, Northwest Territories, Canada, with a large retrogressive thaw slump (nearly 1 kilometre in diameter) within its catchment. A radiocarbon date from the base of the FM1 sediment core suggests the lake formed between 990-1160 Cal AD. The analysis of aerial photographs indicate the thaw slump initiated between 1970-1990, and sediment geochemistry analysis indicated major changes in sediment content at 54-cm sediment core depth. Analyses of subfossil midge (Chironomidae) fossils inferred that, pre-slump, lake FM1 was shallow with a large bog or wetland environment, with midge assemblages dominated by taxa such as Limnophyes and Parametriocnemus. Post-thaw midge assemblages were dominated by subfamily Chironominae (Tribe Tanytarsini and Tribe Chironomini) taxa, and the appearance of deepwater-associated taxa such as Sergentia suggests that lake FM1 deepened, possibly as a result of alluvial damming from slump materials washing into the lake near its outlet. Most recent stratigraphic intervals infer a reversion back to shallower conditions, with a slight recovery of bog or wetland-associated midge taxa, possibly due to rapid basin infilling from increased deposition rates of catchment-derived materials. Results emphasize that there may be a variety of different outcomes to Arctic lake and pond ecosystems as a result of permafrost thawing, contingent on system-specific characteristics such as slump location relative to the lake basin, and relative inflow and outflow locations within the lake basin.

  1. The levels and composition of persistent organic pollutants in alluvial agriculture soils affected by flooding.

    PubMed

    Maliszewska-Kordybach, Barbara; Smreczak, Bozena; Klimkowicz-Pawlas, Agnieszka

    2013-12-01

    The concentrations and composition of persistent organic pollutants (POPs) were determined in alluvial soils subjected to heavy flooding in a rural region of Poland. Soil samples (n = 30) were collected from the upper soil layer from a 70-km(2) area. Chemical determinations included basic physicochemical properties and the contents of polychlorinated biphenyls (PCBs), hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs) and polycyclic aromatic hydrocarbons (PAHs, 16 compounds). The median concentrations of ?7PCB (PCB28 + PCB52 + PCB101 + PCB118 + PCB138 + PCB153 + PCB180), ?3HCH (?-HCH + ?-HCH + ?-HCH) and ?3pp'(DDT + DDE + DDD) were 1.60 ± 1.03, 0.22 ± 0.13 and 25.18 ± 82.70 ?g kg(-1), respectively. The median concentrations of the most abundant PAHs, phenanthrene, fluoranthene, pyrene, benzo[b]fluoranthene and benzo[a]pyrene were 50 ± 37, 38 ± 27, 29 ± 30, 45 ± 36 and 24 ± 22 ?g kg(-1), respectively. Compared with elsewhere in the world, the overall level of contamination with POPs was low and similar to the levels in agricultural soils from neighbouring countries, except for benzo[a]pyrene and DDT. There was no evidence that flooding affected the levels of POPs in the studied soils. The patterns observed for PAHs and PCBs indicate that atmospheric deposition is the most important long-term source of these contaminants. DDTs were the dominant organochlorine pesticides (up to 99%), and the contribution of the parent pp' isomer was up to 50 % of the ?DDT, which indicates the advantage of aged contamination. A high pp'DDE/pp'DDD ratio suggests the prevalence of aerobic transformations of parent DDT. Dominance of the ? isomer in the HCHs implies historical use of lindane in the area. The effect of soil properties on the POP concentrations was rather weak, although statistically significant links with the content of the <0.02-mm fraction, Ctotal or Ntotal were observed for some individual compounds in the PCB group. PMID:23877573

  2. Paleomagnetism and rock magnetism of Quaternary volcanic rocks and late Paleozoic strata. VC1 core hole, Valles caldera, New Mexico, with emphasis on remagnetization of late paleozoic strata

    Microsoft Academic Search

    John W. Geissman

    1988-01-01

    Paleomagnetic and rock magnetic data obtained from azimuthally unoriented core samples, collected at approximately 1- to 3-m intervals, of Continental Scientific Drilling Program core hole VC-1 have prompted reinterpretations of the Quaternary volcanic stratigraphy intersected by the bore and have aided in evaluating the thermal regime within late Paleozoic strata attending fluid circulation and mineral deposition during and after development

  3. Wrench tectonics control on Neogene-Quaternary sedimentation along the Mid-Hungarian Mobile Belt

    NASA Astrophysics Data System (ADS)

    Pogacsas, Gyorgy; Juhász, Györgyi; Mádl-Sz?nyi, Judit; Simon, Szilvia; Lukács, Szilveszter; Csizmeg, János

    2010-05-01

    The Neogene Pannonian basin is underlain by a large orogenic collage which is built up by several tectonostratigraphic terrains. The basement of the Pannonian Basin became imbricate nappes during the Cretaceous Alpine collision. Nappes of Late Cretaceous in age have been proven below the Great Hungarian Plain (Grow et al 1994). The boundary of the two main terrains, the northwestern ALCAPA (Alpine-Carpathian-Pannonian) and the southeastern TISZA, is the Mid-Hungarian Mobile Belt. It is the most significant neotectonic zone of the Pannonian Basin. The structural analysis of the middle section of the Mid-Hungarian Mobile Belt was carried out on a 120km x 50km area, between the Danube and the Tisza river, on the basis of interpretation of seismic data. The structural analysis of the Neogene-Quaternary sediments was supported by sequence stratigraphic interpretation of seismic, well log and core-sample data. Regional seismic profiles were both oriented in the dip direction, which highlights sediment supply routes into the basin, and strike-oriented. The studied segment of the Mid-Hungarian Mobile Belt consists of several long (some ten kilometres long) strike slip fault zones. The offset lengths of the individual strike slipe faults varies between a few and a dozens of kilometres. Activity along the Mid-Hungarian Mobile Belt can be characterised by four periods, the size and shape of facies zones of each development period were controlled by tectonics: 1. During the early Miocene, the ALPACA moved eastward, bounded by sinistral strike-slipe system along its northern side and dextral strike-slipe fault system along its contact with the Southern Alps and the TISZA terrain. The largest movement took part during the Ottnangian-Karpatian (19-16.5 Ma). The TISZA unit moved northeastward over the remnant Carpathian Flysch Basin (Nemcok et al 2006). These terrains movements resulted in right lateral, convergent wide wrench along the Mid-Hungarian Mobile Belt. The ALPACA terrain, lying originally between the Central Alpine and Southern Alpine units, reached its recent position by some hundred kilometers strike slip movement, resulting in shifting of depocenters from the SW toward NE. The TISZA unit was characterised by clockwise motion, while counterclockwise rotation of the ALPACA is inferred in Late Oligocene-Miocene. Lower Miocene layers were deposited in depocenters whose subsidence was initiated by escape tectonics, NE-ward displacement of the ALCAPA terrane, and uplifting of the NW-SE oriented Neo-Vardar zone. The Neo-Vardar zone was represented by wide area of continental and alluvial depositional systems. 2. During the middle-late Badenian (15.5-13.6Ma), the ALCAPA collided with the European platform, and the eastward movement of the Tisza-Dacia became pronounced. Because of that the former right lateral motion along the Mid-Hungarian Mobile Belt ceased and a long period of left lateral strike slipe began. Earlier development of pull-apart basins, related to the extensive strike-slip faulting inside the ALCAPA, changed to the graben opening driven by the westward subduction and the eastward motion of the Tisza-Dacia. The middle-late Badenian period was characterised by sediments deposited in listric fault bounded half grabens, in crestal collapse grabens related to (flat-ramp) listric faults, in wide and/or narrow rift systems. Migration of volcanic activity and facies belts took place during relatively short period of times. Large displacements along listric faults have resulted in tilting of originally horizontal strata, and the formation of a regional unconformity between the middle Miocene and the upper Miocene sediments. Wrench fault related pull apart basins were filled by terrestrial to marine sediments. 3. During the Sarmatian-Pannonian (13.6-6.2 Ma), while the eastward motion of the ALPACA was strictly restricted, the Tisza-Dacia unit was able still to move eastward until the last parts of the remnant Carpathian Flysch Basin were overridden by the Carpathian orogen. An estimation of 8-10 km magnitude of Late Miocene

  4. Characterization of debris avalanche deposits in Japan

    NASA Astrophysics Data System (ADS)

    Ui, Tadahide; Yamamoto, Hiroshi; Suzuki-Kamata, Keiko

    1986-09-01

    Seventy-one debris avalanche deposits are identified from 52 Japanese Quaternary volcanoes. The structures of these volcanoes are mostly stratovolcanoes and lava domes. No avalanche deposit is found in calderas, pyroclastic cones or maar volcanoes. Debris avalanche deposits are found in 18% of all Quaternary volcanoes or 25% of Quaternary stratovolcanoes and lava domes. The ratio rises to 49% when considering only active stratovolcanoes and lava domes. At least five debris avalanche deposits have formed since 9th century. The maximum height difference of sliding ( H) for each debris avalanche ranges from 200 to 2400 meters and the maximum runout distance of sliding ( L) ranges from 1.6 to 32 km. The ratio H/ L ranges from 0.2 to 0.06, and becomes smaller in larger debris avalanches. They are more mobile than landslides in non-volcanic areas. Volume is within a range of 0.03 and 9 km 3. There is no relation between the direction of sliding and the regional horizontal compressional stress axis at the site of a volcano. Two-dimensional computer simulations of avalanches using a simplified physical model are made. The maximum velocity is mainly controlled by the length of steep slope.

  5. Waste rice for waterfowl in the Mississippi Alluvial Valley

    USGS Publications Warehouse

    Stafford, J.D.; Kaminski, R.M.; Reinecke, K.J.; Manley, S.W.

    2006-01-01

    Flooded rice fields are important foraging habitats for waterfowl in the lower Mississippi Alluvial Valley (MAV). Waste rice previously was abundant in late autumn (140?492 kg/ha), but early planting and harvest dates in recent years may have increased losses of waste rice during autumn before waterfowl arrive. Research in Mississippi rice fields revealed waste-rice abundance decreased 79?99% during autumns 1995?1996. To determine if this trend existed throughout the MAV, we used multistage sampling (MSS) to estimate waste-rice abundance during September?December 2000?2002. Averaged over years, mean abundance of waste rice decreased 71% between harvest ((x) over bar = 271.0 kg/ha, CV = 13% n = 3 years) and late autumn ( (x) over bar = 78.4 kg/ha, CV = 15% n = 3). Among 15 models formulated to explain variation in rice abundance among fields and across years, the best model indicated abundance of waste rice in late autumn differed between harvester types (i.e., conventional > stripper header) and was positively related to initial waste-rice abundance after harvest. Because abundance of waste rice in late autumn was less than previous estimates in all 3 years, we concluded that waterfowl conservationists have overestimated carrying capacity of rice fields for wintering waterfowl by 52?83% and recommend 325 duck-use days/ha (DUDs) as a revised estimate. We suggest monitoring advances in rice harvest dates to determine when new surveys are warranted and recommend increased management of moist-soil wetlands to compensate for decreased rice abundance.

  6. Evaluation of reforestation in the Lower Mississippi River Alluvial Valley

    USGS Publications Warehouse

    King, S.L.; Keeland, B.D.

    1999-01-01

    Only about 2.8 million ha of an estimated original 10 million ha of bottomland hardwood forests still exist in the Lower Mississippi River Alluvial Valley (LMAV) of the United States. The U.S. Fish and Wildlife Service, the U.S. Forest Service, and state agencies initiated reforestation efforts in the late 1980s to improve wildlife habitat. We surveyed restorationists responsible for reforestation in the LMAV to determine the magnitude of past and future efforts and to identify major limiting factors. Over the past 10 years, 77,698 ha have been reforested by the agencies represented in our survey and an additional 89,009 ha are targeted in the next 5 years. Oaks are the most commonly planted species and bare-root seedlings are the most commonly used planting stock. Problems with seedling availability may increase the diversity of plantings in the future. Reforestation in the LMAV is based upon principles of landscape ecology; however, local problems such as herbivory, drought, and flooding often limit success. Broad-scale hydrologic restoration is needed to fully restore the structural and functional attributes of these systems, but because of drastic and widespread hydrologic alterations and socioeconomic constraints, this goal is generally not realistic. Local hydrologic restoration and creation of specific habitat features needed by some wildlife and fish species warrant attention. More extensive analyses of plantings are needed to evaluate functional success. The Wetland Reserve Program is a positive development, but policies that provide additional financial incentives to landowners for reforestation efforts should be seriously considered.

  7. Progressively cooler, drier interglacials in southern Russia through the Quaternary: Evidence from the Sea of Azov region

    Microsoft Academic Search

    A. A. Velichko; N. R. Catto; M. Yu Kononov; T. D. Morozova; E. Yu Novenko; P. G. Panin; G. Ya Ryskov; V. V. Semenov; S. N. Timireva; V. V. Titov; A. S. Tesakov

    2009-01-01

    Loess-palaeosol exposures along Taganrog Bay, Sea of Azov, in southern Russia, reveal a complex succession of Quaternary palaeoenvironments over the past 0.7 million years. The deposits overlie marine sediments of Tiraspolian (Cromerian) age. At the key section of Semibalki-1, four palaeosol complexes are identified within the series. The earliest palaeosol complex in the Semibalki-1 section is correlated with the late

  8. Alternative chronologies for Late Quaternary (Last Interglacial–Holocene) deep sea sediments via optical dating of silt-sized quartz

    Microsoft Academic Search

    S. Stokes; S. Ingram; M. J. Aitken; F. Sirocko; R. Anderson; D. Leuschner

    2003-01-01

    We summarize the results of a test on the potential of optical dating for the age assessment of Late Quaternary deep-sea sediments. Our approach combines a single aliquot regeneration (SAR) protocol for equivalent dose (De) estimation on fine silt-sized quartz with a time-dependent evaluation of supported and unsupported long-lived radioisotopes within the deposited sediment matrix. For this purpose nine samples

  9. Exceptionally well preserved late Quaternary plant and vertebrate fossils from a blue hole on Abaco, The Bahamas

    Microsoft Academic Search

    D. W. Steadman; Richard Franz; G. S. Morgan; N. A. Albury; Brian Kakuk; Kenneth Broad; S. E. Franz; Keith Tinker; M. P. Pateman; T. A. Lott; D. M. Jarzen; D. L. Dilcher

    2007-01-01

    We report Quaternary vertebrate and plant fossils from Sawmill Sink, a ''blue hole'' (a water-filled sinkhole) on Great Abaco Island, The Bahamas. The fossils are well preserved because of deposition in anoxic salt water. Vertebrate fossils from peat on the talus cone are radiocarbon-dated from 4,200 to 1,000 cal BP (Late Holocene). The peat produced skeletons of two extinct species

  10. Liquefaction probability curves for surficial geologic deposits

    USGS Publications Warehouse

    Holzer, Thomas L.; Noce, Thomas E.; Bennett, Michael J.

    2011-01-01

    Liquefaction probability curves that predict the probability of surface manifestations of earthquake-induced liquefaction are developed for 14 different types of surficial geologic units. The units consist of alluvial fan, beach ridge, river delta topset and foreset beds, eolian dune, point bar, flood basin, natural river and alluvial fan levees, abandoned river channel, deep-water lake, lagoonal, sandy artificial fill, and valley train deposits. Probability is conditioned on earthquake magnitude and peak ground acceleration. Curves are developed for water table depths of 1.5 and 5.0 m. Probabilities are derived from complementary cumulative frequency distributions of the liquefaction potential index (LPI) that were computed from 927 cone penetration tests. For natural deposits with a water table at 1.5 m and subjected to a M7.5 earthquake with peak ground acceleration (PGA) ?=? 0.25g, probabilities range from 0.5 for beach ridge, point bar, and deltaic deposits. The curves also were used to assign ranges of liquefaction probabilities to the susceptibility categories proposed previously for different geologic deposits. For the earthquake described here, probabilities for susceptibility categories have ranges of 0–0.08 for low, 0.09–0.30 for moderate, 0.31–0.62 for high, and 0.63–1.00 for very high. Retrospective predictions of liquefaction during historical earthquakes based on the curves compare favorably to observations.

  11. Perchlorate removal by quaternary amine modified reed

    Microsoft Academic Search

    Salem Baidas; Baoyu Gao; Xiaoguang Meng

    2011-01-01

    We report a kinetic and equilibrium study of perchlorate adsorption onto giant reed modified by quaternary amine (QA) functional groups in batch reactors. The effect of pH, contact time, and initial perchlorate concentration on removal was investigated. The adsorption capacity for perchlorate was 169mg\\/g on the modified reed (MR) particles ranging in size from 100 to 250?m. The isotherm results

  12. Hydration effects in quaternary amine extraction systems

    Microsoft Academic Search

    J. D. Miller; M. C. Fuerstenau

    1970-01-01

    The extraction of Al+++, Cd++, Co++, Cu+, Cu++, Fe++, Fe+++, In+++, Ni++, and Zn++ with quaternary amine was studied using chloride and sulfate as ligands. On the basis of loading experiments and slope analyses,\\u000a the species extracted were: CdCl4=, CoCl4=, CuCl2?, CuCl4=, FeCl4?, and ZnCl4=. Water content of the organic phase was analyzed as a function of loading by Karl

  13. Palladium-catalyzed asymmetric quaternary stereocenter formation.

    PubMed

    Gottumukkala, Aditya L; Matcha, Kiran; Lutz, Martin; de Vries, Johannes G; Minnaard, Adriaan J

    2012-05-29

    An efficient palladium catalyst is presented for the formation of benzylic quaternary stereocenters by conjugate addition of arylboronic acids to a variety of ?,?-disubstituted carbocyclic, heterocyclic, and acyclic enones. The catalyst is readily prepared from PdCl(2), PhBOX, and AgSbF(6), and provides products in up to 99% enantiomeric excess, with good yields. Based on this strategy, (-)-?-cuparenone has been prepared in only two steps. PMID:22532469

  14. 40 CFR 721.9075 - Quaternary ammonium salt of fluorinated alkylaryl amide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false Quaternary ammonium salt of fluorinated alkylaryl amide. 721...Substances § 721.9075 Quaternary ammonium salt of fluorinated alkylaryl amide. ...identified generically as quaternary ammonium salt of fluorinated alkylaryl amide...

  15. 40 CFR 721.9075 - Quaternary ammonium salt of fluorinated alkylaryl amide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false Quaternary ammonium salt of fluorinated alkylaryl amide. 721...Substances § 721.9075 Quaternary ammonium salt of fluorinated alkylaryl amide. ...identified generically as quaternary ammonium salt of fluorinated alkylaryl amide...

  16. Quaternary Geologic Map of the Des Moines 4 Degrees x 6 Degrees Quadrangle, United States

    USGS Publications Warehouse

    Hallberg, George R., (compiler); Lineback, Jerry A.; Mickelson, David M.; Knox, James C.; Goebel, Joseph E.; Hobbs, Howard C.; Whitfield, John W.; Ward, Ronald A.; Boellstorff, John D.; Swinehart, James B.; Dreeszen, Vincent H.; edited and integrated by Richmond, Gerald Martin; Fullerton, David S.; Christiansen, Ann Coe

    1994-01-01

    The Quaternary Geologic Map of the Des Moines 4 degree x 6 degree Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale. This map is part of the Quaternary Geologic Atlas of the United States (I-1420). It was first published as a printed edition in 1994. The geologic data have now been captured digitally and are presented here along with images of the printed map sheet and component parts as PDF files.

  17. Quaternary Geologic Map of the Platte River 4 Degrees x 6 Degrees Quadrangle, United States

    USGS Publications Warehouse

    Swinehart, James B., (compiler); Dreeszen, Vincent H.; Richmond, Gerald Martin; Tipton, Merlin J.; Bretz, Richard F.; Steece, Fred V.; Hallberg, George R.; Goebel, Joseph E.; edited and integrated by Richmond, Gerald Martin

    1994-01-01

    The Quaternary Geologic Map of the Platte River 4 degree x 6 degree Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale. This map is part of the Quaternary Geologic Atlas of the United States (I-1420). It was first published as a printed edition in 1994. The geologic data have now been captured digitally and are presented here along with images of the printed map sheet and component parts as PDF files.

  18. Foraminiferal biostratigraphy of the shelf edge: a key to late Quaternary paleoenvironments

    USGS Publications Warehouse

    Poag, C. Wylie; Sidner, B.R.

    1976-01-01

    Foraminiferal assemblages in eight piston cores from West Flower Garden Bank at the edge of the Texas continental shelf contain a nearly complete record of late Quaternary paleoclimatic and geologic events. The faunas are divisible into three distinct successive biofacies on the basis of both planktonic and benthic foraminifers: the basal Inflata Facies accumulated in cool shallow waters during late Pleistocene glaciation; the middle Crassaformis Facies represents a deepening sea that had warming surface waters; the upper Cultrata Facies is characteristic of the Holocene outer-shelf environment. Sea level was at -73 m and -53 m at the end of deposition of the Inflata and Crassaformis Facies, respectively. The biostratigraphic events at West Flower Garden Bank can be accurately correlated with those recorded in the middle and inner shelf and in deep-sea cores. The sequence of late Quaternary sea level and paleotemperature changes in the northern Gulf of Mexico can thereby be reconstructed. Eventually, this knowledge can be integrated with similar data from the shelf edge in other parts of the world to help bridge the gap between the known Quaternary record of the deep sea and that of the continents. ?? 1976.

  19. Quaternary geologic map of the Blue Ridge 4 degrees x 6 degrees quadrangle, United States

    USGS Publications Warehouse

    State compilations by Howard, Alan D.; Behling, Robert E.; Wheeler, Walter H.; Daniels, Raymond B.; Swadley, W.C.; Richmond, Gerald M.; Goldthwait, Richard P.; Sevon, William D.; Miller, Robert A.; Edited and integrated by Richmond, Gerald M.; Fullerton, David S.; Christiansen, Ann Coe; Digital edition by Bush, Charles A.

    1991-01-01

    This map is part of the Quaternary Geologic Atlas of the United States (I-1420). It was first published as a printed edition in 1986. The geologic data have now been captured digitally and are presented here along with images of the printed map sheet and component parts as PDF files. The Quaternary Geologic Map of the Blue Ridge 4° x 6° Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the "ground" on which we walk, the "dirt" in which we dig foundations, and the "soil" in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

  20. Significance of paleosols in alluvial architecture: Example from Upper Jurassic Morrison Formation, Colorado Plateau

    SciTech Connect

    Mantzios, C. (Univ. of Nebraska, Lincoln (USA))

    1989-09-01

    Paleosols are rapidly becoming an important and essential aspect of alluvial architecture. Their diversity can be used extensively in detailing important subenvironments of major alluvial systems. The Upper Jurassic Morrison Formation in the Colorado Plateau exhibits some of the best examples of alluvial paleosols yet known. Three-dimensional exposures are used to illustrate the relationships between the various alluvial subenvironments. Paleosols are better developed on meandering-channel systems where the overbank areas are much broader compared to braided-channel systems where paleosol profiles are thin and less well developed. A great variation also exists between paleosols which were developed on different subenvironments. This variability ranges from degree of development (maturity) of the soil profile to the presence or absence of certain pedogenic features. Three processes are responsible for the development of the soil profiles: sedimentation, pedogenesis, and diagenesis. All three processes must be differentiated and considered separately. Sedimentation rates the paleosols to the channels, distinguishes soil profiles, and helps explain compound pedogenesis. Diagenesis reflects mineralogical alterations which may be related to climatic conditions, soil horizon coloration which does not necessarily reflect horizon boundaries, and processes such as silicification, calcification, and concretion development. Pedogenesis acts in various degrees reflecting climate, topography, vegetation, parent material, and time. All these aspects of paleosols can be used effectively to reconstruct ancient alluvial architecture. The Morrison Formation is a prime example because of its great regional extent and excellent outcrops.

  1. Reconnaissance study of late quaternary faulting along cerro GoDen fault zone, western Puerto Rico

    USGS Publications Warehouse

    Mann, P.; Prentice, C.S.; Hippolyte, J.-C.; Grindlay, N.R.; Abrams, L.J.; Lao-Davila, D.

    2005-01-01

    The Cerro GoDen fault zone is associated with a curvilinear, continuous, and prominent topographic lineament in western Puerto Rico. The fault varies in strike from northwest to west. In its westernmost section, the fault is ???500 m south of an abrupt, curvilinear mountain front separating the 270- to 361-m-high La CaDena De San Francisco range from the Rio A??asco alluvial valley. The Quaternary fault of the A??asco Valley is in alignment with the bedrock fault mapped by D. McIntyre (1971) in the Central La Plata quadrangle sheet east of A??asco Valley. Previous workers have postulated that the Cerro GoDen fault zone continues southeast from the A??asco Valley and merges with the Great Southern Puerto Rico fault zone of south-central Puerto Rico. West of the A??asco Valley, the fault continues offshore into the Mona Passage (Caribbean Sea) where it is characterized by offsets of seafloor sediments estimated to be of late Quaternary age. Using both 1:18,500 scale air photographs taken in 1936 and 1:40,000 scale photographs taken by the U.S. Department of Agriculture in 1986, we iDentified geomorphic features suggestive of Quaternary fault movement in the A??asco Valley, including aligned and Deflected drainages, apparently offset terrace risers, and mountain-facing scarps. Many of these features suggest right-lateral displacement. Mapping of Paleogene bedrock units in the uplifted La CaDena range adjacent to the Cerro GoDen fault zone reveals the main tectonic events that have culminated in late Quaternary normal-oblique displacement across the Cerro GoDen fault. Cretaceous to Eocene rocks of the La CaDena range exhibit large folds with wavelengths of several kms. The orientation of folds and analysis of fault striations within the folds indicate that the folds formed by northeast-southwest shorTening in present-day geographic coordinates. The age of Deformation is well constrained as late Eocene-early Oligocene by an angular unconformity separating folDed, Deep-marine middle Eocene rocks from transgressive, shallow-marine rocks of middle-upper Oligocene age. Rocks of middle Oligocene-early Pliocene age above unconformity are gently folDed about the roughly east-west-trending Puerto Rico-Virgin Islands arch, which is well expressed in the geomorphology of western Puerto Rico. Arching appears ongoing because onshore and offshore late Quaternary oblique-slip faults closely parallel the complexly Deformed crest of the arch and appear to be related to exTensional strains focused in the crest of the arch. We estimate ???4 km of vertical throw on the Cerro GoDen fault based on the position of the carbonate cap north of the fault in the La CaDena De San Francisco and its position south of the fault inferred from seismic reflection data in Mayaguez Bay. Based on these observations, our interpretation of the kinematics and history of the Cerro GoDen fault zone incluDes two major phases of motion: (1) Eocene northeast-southwest shorTening possibly accompanied by left-lateral shearing as Determined by previous workers on the Great Southern Puerto Rico fault zone; and (2) post-early Pliocene regional arching of Puerto Rico accompanied by normal offset and right-lateral shear along faults flanking the crest of the arch. The second phase of Deformation accompanied east-west opening of the Mona rift and is inferred to continue to the present day. ?? 2005 Geological Society of America.

  2. Palaeohydrological and palaeoecological studies on South Cameroonian alluvial sedimentary basins - New evidence on the palaeoenvironmental evolution of western Central Africa since the Late Pleistocene

    NASA Astrophysics Data System (ADS)

    Sangen, M.

    2009-04-01

    A new valuable and innovative contribution will be presented to ascertain the timing and extension of climatic and ecological changes in western equatorial Africa. Main focus is laid on the dynamics of climate, fluvial systems and the high sensitive tropical ecosystems (dense evergreen and semi-deciduous rain forest and savanna-rain forest margin) since the Late Pleistocene (~50 kyrs. BP). For this purpose extended fieldworks were carried out in South Cameroon (2004-2008) by the ReSaKo-Project (sub-project of DFG-Project 510) with abundant investigations on alluvial sedimentary basins of equatorial tropical fluvial systems. Suitable alluvial sediment-archives for palaeoenvironmental research were uncovered along selected braiding, meandering and anabranching/anastomosing reaches of major southwestern, into the Gulf of Guinea (Ntem, Nyong and Sanaga) and southeastern, into the Congo basin (Boumba, Dja and Ngoko) draining rivers (RUNGE et al. 2006, SANGEN 2008). Among geomorphological investigations and cross section discussions, 150 corings (Edelman, 20 cm layers) reaching maximum depths of 550 cm were carried out on river benches, levees, cut-off and periodical branches, islands and terraces as well as in seasonal inundated floodplains and backswamps. Corresponding sedimentary profiles and catenae recovered multilayered, sandy to clayey alluvia containing sedimentary form-units and palaeosurfaces which contribute to the reconstruction of palaeoenvironmental conditions in western equatorial Africa. Several (59) radiocarbon (AMS) dated samples (Erlangen and Lecce) from fossil organic layers and macro-rests embedded in these units yielded Late Pleistocene to recent ages (14C-ages around 48 to 0.2 kyrs. BP), spanning also the Last Glacial Maximum (LGM) and Holocene record. Abrupt grain-size modifications and alternating form-units (sandy and clayey layers, palaeosurfaces) in the stratigraphic records display fluctuations in the fluvial-morphological response of the fluvial systems to climatic variability and other extrinsic and intrinsic impacts. Although the sedimentary record varies among the studied river reaches, fossil organic sediment layers (palaeosurfaces) containing valuable proxy data were found in almost all alluvia basins of examined southern Cameroonian rivers. Around 56 ^13C-values corresponding to the dated samples (-31.4 to -18.0 ) evidence that despite major disturbances of the African rain forest over geological times (MALEY 2001) mainly rain forest ecosystems have prevailed during the corresponding time periods, presumably as gallery forests, which were able to persist in this fluvial habitat ("fluvial refuge"), even during arid periods (e.g. LGM). The results are consistent with earlier findings from lacustrine (SERVANT & SERVANT-VILDARY 2000), marine (WELDEAB et al. 2007) and additional sediment archives (GASSE et al. 2008) and will add additional insights and information to the unravelling of the complex respond of the African monsoon, the Central African ecosystems and fluvial systems to Late Quaternary climatic and environmental fluctuations within a globally teleconnected system. References: GASSE, F., CHALIé, F., VINCENS, A., WILLIAMS, M.A.J. & WILLIAMSON, D. (2008): Climatic patterns in equatorial and southern Africa from 30,000 to 10,000 years ago reconstructed from terrestrial and near-shore proxy data. Quaternary Science Reviews, 27 (25-26), 2316-2340. MALEY, J. (2001): The impact of arid phases on the African rain forest through geological history. In: WEBER, W., WHITE, L., VEDDER, A., NAUGHTON-TREVES, L. (Eds.): African rain forest ecology and conservation - An interdisciplinary perspective. Yale University Press, New Haven, 68-87. RUNGE, J., EISENBERG, J., SANGEN, M. (2006): Geomorphic evolution of the Ntem alluvial basin and physiogeographic evidence for Holocene environmental changes in the rain forest of SW Cameroon (Central Africa) - preliminary results. Z. Geomorph. N.F., Suppl. Bd. 145, 63-79. SERVANT, M. & SERVANT-VILDARY, S. (2000): Dynamique à long terme des

  3. New insights into the earliest Quaternary environments in the Central North Sea from 3D seismic

    NASA Astrophysics Data System (ADS)

    Lamb, Rachel; Huuse, Mads; Stewart, Margaret; Brocklehurst, Simon H.

    2014-05-01

    In the past the transition between an unconformable surface in the south to a conformable horizon towards the north has made identification and mapping the base-Quaternary in the central North Sea difficult (Sejrup et al 1991; Gatliff et al 1994). However recent integration of biostratigraphy, pollen analysis, paleomagnetism and amino acid analysis in the Dutch and Danish sectors (Rasmussen et al 2005; Kuhlmann et al 2006) has allowed greater confidence in the correlation to the region 3D seismic datasets and thus has allowed the base-Quaternary to be mapped across the entire basin. The base-Quaternary has been mapped using the PGS MegaSurvey dataset from wells in the Danish Sector along the initially unconformable horizon and down the delta front into the more conformable basin giving a high degree of confidence in the horizon pick. The revised base-Quaternary surface reaches a depth of 1248 ms TWT with an elongate basin shape which is significantly deeper than the traditionally mapped surface. Using RMS amplitudes and other seismic attributes the revised base-Quaternary has been investigated along the horizon and in time slice to interpret the environments of the earliest Quaternary prior to the onset of glaciation. Combined with analysis of aligned elongate furrows over 10 km long, 100 m wide and 100 m deep suggest a deep marine environment in an almost enclosed basin with persistent strong NW-SE bottom currents in the deepest parts. Pockmarks were formed by the escape of shallow gas on the sides of a small delta in the eastern part of the basin. The progradation of large deltas from both the north and south into the basin make up the majority of the deposition of sediment into the basin. Key Words: base-Quaternary; seismic interpretation; paleoenvironments References: Gatliff, R.W, Richards, P.C, Smith, K, Graham, C.C, McCormac, M, Smith, N.J.P, Long, D, Cameron, T.D.J, Evans, D, Stevenson, A.G, Bulat, J, Ritchie, J.D, (1994) 'United Kingdom offshore regional report: the geology of the central North Sea.' London: HMSO for the British Geological Survey Kuhlmann, G., Langereis C.G., Munsterman, D., van Leeuwen, R.-J., Verreussel, R., Meulenkamp, J.E., Wong, Th.E., 2006 'Intergrated chronostratigraphy of the Pliocene-Pliestocene interval and its relation to the regional stratigraphical stages in the Southern North Sea region' Netherlands Journal of Geosciences 85(1), 29-45 Rasmussen, E.A., Vejb?k O.V., Bidstrup, T., Piasecki, S., Dybkj?r, K., 2005 'Late Cenozoic depositional history of the Danish North Sea Basin: implications for the petroleum systems in the Kraka, Halfdan, Siri and Nini fields', Petroleum Geology Conference series 6, 1347-1358 Sejrup, H.P., Aareseth, I., Haflidason, H., 1991 'The Quaternary succession in the northern North Sea' Marine Geology 101 103-111

  4. Occurrence and downslope mobilization of quaternary herbicide residues in vineyard-devoted soils.

    PubMed

    Pateiro-Moure, Mirian; Arias-Estévez, Manuel; López-Periago, Eugenio; Martínez-Carballo, Elena; Simal-Gándara, Jesús

    2008-05-01

    The aim of this study was to examine the fate of quaternary herbicides in soil deposits derived from erosion of vineyard-devoted soils. Herbicide occurrence in the crop soils was due to the farmer application inputs. Special attention should be paid to the presence of paraquat (PQ) in the studied vineyard-devoted soils. The major factor governing the sorption of PQ was the solid state organic fraction with the clay mineral content also making a significant contribution. The mobilization and transport of quats-enriched soil particles may generate downslope and downstream environmental problems that mainly affect detritivore ecology. PMID:18389162

  5. Stratigraphy of Aeolis Dorsa, Mars: Stratigraphic context of the great river deposits

    NASA Astrophysics Data System (ADS)

    Kite, Edwin S.; Howard, Alan D.; Lucas, Antoine S.; Armstrong, John C.; Aharonson, Oded; Lamb, Michael P.

    2015-06-01

    Unraveling the stratigraphic record is the key to understanding ancient climate and past climate changes on Mars (Grotzinger, J. et al. [2011]. Astrobiology 11, 77-87). Stratigraphic records of river deposits hold particular promise because rain or snowmelt must exceed infiltration plus evaporation to allow sediment transport by rivers. Therefore, river deposits when placed in stratigraphic order could constrain the number, magnitudes, and durations of the wettest (and presumably most habitable) climates in Mars history. We use crosscutting relationships to establish the stratigraphic context of river and alluvial-fan deposits in the Aeolis Dorsa sedimentary basin, 10°E of Gale crater. At Aeolis Dorsa, wind erosion has exhumed a stratigraphic section of sedimentary rocks consisting of at least four unconformity-bounded rock packages, recording three or more distinct episodes of surface runoff. Early deposits (>700 m thick) are embayed by river deposits (>400 m thick), which are in turn unconformably draped by fan-shaped deposits (<100 m thick) which we interpret as alluvial fans. Yardang-forming layered deposits (>900 m thick) unconformably drape all previous deposits. River deposits embay a dissected landscape formed of sedimentary rock. The river deposits are eroding out of at least two distinguishable units. There is evidence for pulses of erosion during the interval of river deposition. The total interval spanned by river deposits is >(1 × 106-2 × 107) yr, and this is extended if we include alluvial-fan deposits. Alluvial-fan deposits unconformably postdate thrust faults which crosscut the river deposits. This relationship suggests a relatively dry interval of >4 × 107 yr after the river deposits formed and before the fan-shaped deposits formed, based on probability arguments. Yardang-forming layered deposits unconformably postdate all of the earlier deposits. They contain rhythmite and their induration suggests a damp or wet (near-) surface environment. The time gap between the end of river deposition and the onset of yardang-forming layered deposits is constrained to >1 × 108 yr by the high density of impact craters embedded at the unconformity. The time gap between the end of alluvial-fan deposition and the onset of yardang-forming layered deposits was at least long enough for wind-induced saltation abrasion to erode 20-30 m into the alluvial-fan deposits. We correlate the yardang-forming layered deposits to the upper layers of Gale crater's mound (Mt. Sharp/Aeolis Mons), and the fan-shaped deposits to Peace Vallis fan in Gale crater. Alternations between periods of low mean obliquity and periods of high mean obliquity may have modulated erosion-deposition cycling in Aeolis. This is consistent with the results from an ensemble of simulations of Solar System orbital evolution and the resulting history of the obliquity of Mars. 57 of our 61 simulations produce one or more intervals of continuously low mean Mars obliquity that are long enough to match our Aeolis Dorsa unconformity data.

  6. Event scale variability of mixed alluvial-bedrock channel dynamics

    NASA Astrophysics Data System (ADS)

    Cook, Kristen; Turowski, Jens; Hovius, Niels

    2015-04-01

    The relationship between flood events and fluvial behavior is critical for understanding how rivers may respond to the changing hydrologic forcing that may accompany climate change. In mixed bedrock-alluvial rivers, the response of the system to a flood event can be affected by a large number of factors, including coarse sediment availability in the channel, sediment supply from the hillslopes, bedrock-controlled changes in channel width and planform, and the shape of the hydrograph. We use the Daan River Gorge in western Taiwan as a case study to directly observe the effect of individual flood events on channel evolution. The 1200 m long and up to 20 m deep bedrock gorge formed in response to uplift of the riverbed during the 1999 Chi-Chi earthquake. The extremely rapid pace of change ensures that flood events have measurable and often dramatic effects on the channel. Taiwan is subject to both summer typhoons and a spring monsoon, resulting in numerous channel-altering floods with a range of magnitudes. Discharge is therefore highly variable, ranging from 5 to over 2000 m3/s, and changes in the channel are almost entirely driven by discrete flood events. Since early 2009 we have monitored changes in the gorge with repeated RTK GPS surveys, laser rangefinder measurements, and terrestrial LIDAR surveys. Six rainfall stations and five water level gauges provide hydrological data for the basin. We find a distinct relationship between flood magnitude and the magnitude of geomorphic change; however, we do not find a clear relationship between flood characteristics and the direction of change - whether the channel experienced aggradation or erosion in a particular flood. Upstream coarse sediment supply and the influence of abrupt changes in channel width on bedload flux through the gorge appear to have important influences on the channel response. The better understand these controls, we use the model sedFlow (Heimann et al., 2014) to explore the effects of interactions between sediment supply, channel width, and flood characteristics on aggradation and erosion of the channel bed. Heimann, F. U. M., Rickenmann, D., Turowski, J. M., and Kirchner, J. W.: sedFlow - an efficient tool for simulating bedload transport, bed roughness, and longitudinal profile evolution in mountain streams, Earth Surf. Dynam. Discuss., 2, 733-772, doi:10.5194/esurfd-2-733-2014, 2014.

  7. Valley-fill alluviation during the Little Ice Age (ca. A.D. 1400-1880), Paria River basin and southern Colorado Plateau, United States

    USGS Publications Warehouse

    Hereford, R.

    2002-01-01

    Valley-fill alluvium deposited from ca. A.D. 1400 to 1880 is widespread in tributaries of the Paria River and is largely coincident with the Little Ice Age epoch of global climate variability. Previous work showed that alluvium of this age is a mappable stratigraphic unit in many of the larger alluvial valleys of the southern Colorado Plateau. The alluvium is bounded by two disconformities resulting from prehistoric and historic arroyo cutting at ca. A.D. 1200-1400 and 1860-1910, respectively. The fill forms a terrace in the axial valleys of major through-flowing streams. This terrace and underlying deposits are continuous and interfinger with sediment in numerous small tributary valleys that head at the base of hillslopes of sparsely vegetated, weakly consolidated bedrock, suggesting that eroded bedrock was an important source of alluvium along with in-channel and other sources. Paleoclimatic and high-resolution paleoflood studies indicate that valley-fill alluviation occured during a long-term decrease in the frequency of large, destructive floods. Aggradation of the valleys ended about A.D. 1880, if not two decades earlier, with the beginning of historic arroyo cutting. This shift from deposition to valley entrenchment near the close of the Little Ice Age generally coincided with the beginning of an episode of the largest floods in the preceding 400-500 yr, which was probably caused by an increased recurrence and intensity of flood-producing El Nin??o events beginning at ca. A.D. 1870.

  8. Tectonically induced climate and its control on the distribution of depositional systems in a continental foreland basin, Cloverly and Lakota Formations (Lower Cretaceous) of Wyoming, U.S.A.

    NASA Astrophysics Data System (ADS)

    Elliott, William S.; Suttner, Lee J.; Pratt, Lisa M.

    2007-12-01

    Continental sediments of the Cloverly and Lakota Formations (Lower Cretaceous) in Wyoming are subdivided into three depositional systems: perennial to intermittent alluvial, intermittent to ephemeral alluvial, and playa. Chert-bearing sandstones, conglomerates, carbonaceous mudrocks, blocky mudrocks, and skeletal limestones were deposited by perennial to intermittent alluvial systems. Carbonaceous mudrocks contain abundant wood fragments, cuticle and cortical debris, and other vascular plant remains representing deposition in oxbow lakes, abandoned channels, and on floodplains under humid to seasonal conditions. Intraformational conglomerates, sandstones, bioturbated and blocky mudrocks with caliche nodules, and bioturbated limestones characterize deposition in intermittent to ephemeral alluvial systems. Bioturbated limestones are encased in bioturbated mudrocks with abundant pseudo-slickensides. The presence of caliche nodules in some of the blocky to bioturbated mudrocks is consistent with supersaturation and precipitation of calcium carbonate from groundwater under semi-arid conditions. Caliche nodules, pseudo-slickensides, and carbonate-rich floodplain sediments are interpreted to have been deposited by intermittent to ephemeral alluvial systems under seasonal to semi-arid climatic conditions. Laminated mudrocks, siltstones, vuggy carbonates, bedded to nodular evaporites, pebbly mudrocks, and diamictites were deposited in evaporative alkaline lakes or playas. Pebbly mudrocks and diamictites are interpreted to represent deposition from channelized and unchannelized hyperconcentrated flows on a playa, resulting from intense rain events within the basin. The areal abundance and distribution of these depositional systems change systematically across the overfilled portion of the Early Cretaceous Cordilleran foreland basin in Wyoming. The lower part (A-interval) of the Cloverly and Lakota Formations is characterized by deposits of perennial to intermittent rivers that existed 300 to 1000 km east of the Sevier fold-and-thrust belt. Proximal to the Sevier fold-and-thrust belt, the A-interval of the Cloverly Formation and upper Ephraim Formation of the Gannett Group are typified by deposits of intermittent to ephemeral rivers and their associated floodplains. In the middle part (B-interval) of the Cloverly Formation, intermittent to ephemeral alluvial systems expand to 600 km into the basin. The upper part (C-interval) of the Cloverly Formation is characterized by playa deposits in the Bighorn and Wind River Basins and intermittent to ephemeral alluvial deposits along the front of the ancestral Sevier Mountains. Deposits of perennial to intermittent alluvial systems in the C-interval of the Cloverly and Lakota Formations are restricted to the Black Hills region, almost 900 km to the east of the Sevier Mountains. The change in the areal distribution of depositional systems through time within this continental foreland basin may be attributed to the development of a rain shadow associated with the uplift of the Sevier Mountains in the Early Cretaceous.

  9. Dynamics of Groundwater Flow at an Alluvial Fan\\/Playa Margin Interface Based on Inorganic and Isotope Hydrochemistry

    Microsoft Academic Search

    L. M. Vargas; B. J. Hibbs

    2009-01-01

    Mojave Chub (MC) Spring is located at an alluvial fan\\/playa margin interface between Soda Lake and the Soda Mountains, Mojave Desert. Identifying the source flows at MC Spring provides an opportunity to help managers protect the spring and the Mojave tui chub, a listed endangered species that survives in MC Spring. An alluvial fan formed on the flanks of the

  10. Seismic mapping of alluvial fans and sub-fan bedrock in Big Bend National Park, Texas 

    E-print Network

    Monti, Joseph

    1984-01-01

    SEISMIC MAPPING OF ALLUVIAL FANS AND SUB-FAN BEDROCK IN BIG BEND NATIONAL PARK, TEXAS A Thesis JOSEPH MONTI Submitted to the Graduate College of Texas A@M University in partial fulfillment of the requirement of the degree of MASTER OF SCIENCE... May, 1984 Major Subject: Geology SEISMIC MAPPING OF ALLUVIAL FANS AND SUB-FAN BEDROCK IN BIG BEND NATIONAL PARK, TEXAS A Thesis by JOSEPH MONTI Approved as to style and content by: M. C. Schroeder (Chairman of committee) icky M. P. Wilson...

  11. Red Fork sandstone of Oklahoma: depositional history and reservoir distribution

    SciTech Connect

    Shelton, J.W.; Fritz, R.D.; Johnson, C.

    1989-03-01

    The Middle Pennsylvanian Red Fork sandstone formed as a result of progradation across eastern Kansas and most of Oklahoma. The Red Fork is one of several transgressive-regressive sequences (cyclothems) developed within the Desmoinesian Cherokee Group. Sea level changes, together with varying subsidence, were dominant factors controlling the general stratigraphic (correlative) characteristics of the Red Fork interval. Progradation was episodic, with sand deposition in the more active part of the basin during lower sea level stands and valley-fill deposition in the more stable areas during sea level rises. A map of Red Fork sand trends reveals an alluvial-deltaic complex covering most of Oklahoma. The Red Fork consists primarily of alluvial-valley and plain (fluvial) bodies in the northernmost part of northeastern Oklahoma, alluvial-deltaic bodies in most of the remaining parts of the shelf area, and off-shelf submarine-fan and slope basinal-floor complexes within the deeper part of the Anadarko basin. Determination of reservoir trend and genesis requires integration of rock and log data. Logs need to be calibrated to cores in order to estimate depositional environments accurately and to make a reasonable assessment of diagenetic overprints. Much of the oil and gas has been trapped in stratigraphic traps, and a significant amount of oil is in channel sandstones with trends at high angles to the structural grain. In some areas, secondary clay, in particular chloritic clay, has resulted in microporosity, high water saturation, and correspondingly low resistivities in oil reserves.

  12. Late Quaternary environments and biogeography in the Great Basin

    NASA Astrophysics Data System (ADS)

    Thompson, R. S.; Mead, J. I.

    1982-01-01

    Plant and animal remains found in packrat ( Neotoma spp.) middens and cave fill from the eastern and southern Great Basin region reveal the presence of subalpine conifers and boreal mammals at relatively low elevations during the Late Wisconsin. Limber pine ( Pinus flexilis) and bristlecone pine ( P. longaeva) were important in the late Pleistocene plant communities throughout this region. Spruce ( Picea cf. engelmannii) and common juniper ( Juniperus communis) were present in some of the more northerly localities, and Douglas fir ( Pseudotsuga menziesii) and white fir ( Abies concolor) were present in southern and eastern localities. Single needle pinyon pine ( Pinus monophylla), common across this region today, was apparently not present north of the Sheep Range of southern Nevada during the Late Wisconsin. Pikas ( Ochotona cf. princeps), small boreal mammals present in only a few Great Basin mountain ranges today, were common throughout the region. Heather voles ( Phenacomys cf. intermedius) have been found in two cave fill deposits in Nevada, though they are unknown in the Great Basin today. Limber and bristlecone pines are generally restricted to rocky substrates in modern subalpine habitats in the Great Basin, and this may also have been the case when these plants grew at lower elevations during the Late Wisconsin. Subalpine conifers were present on the rock outcrops sampled by the packrat middens, but shrub communities, perhaps dominated by sagebrush ( Artemisia spp.), may have been present on alluvial valley-bottom substrates. Forested habitats would thus have been isolated habitat islands, as they are today. Boreal small mammals, including pikas and heather voles, were able to colonize the Great Basin mountain ranges during the late Pleistocene. We suggest that these mammals were able to survive in the intervening valley-bottoms under a cool-summer climatic regime, and that continuous forest or woodland corridors were not necessary for migration.

  13. Late Quaternary environments, vegetation and agriculture in northern New Zealand

    NASA Astrophysics Data System (ADS)

    Horrocks, M.; Nichol, S. L.; Augustinus, P. C.; Barber, I. G.

    2007-03-01

    A sedimentological and plant microfossil history of the Late Quaternary is preserved in two sediment cores from early Polynesian ditch systems on southern Aupouri Peninsula. The study places human activities into a geomorphological and ecological context and allows comparison of natural and anthropogenic effects on two different geological settings: a floodplain and a relatively closed peat swamp. The data fill part of the current gap in the environmental record from northern New Zealand, namely MIS 3 (57k-26k yr BP). There is evidence for an increase in fire frequency in the region after 40k 14C yr BP, suggesting a shift to drier (and cooler) conditions. Pollen records show that conifer-hardwood forest dominated by podocarps (especially Dacrydium) prevailed prior to Polynesian arrival and deforestation within the last millennium, with Fuscopsora insignificant throughout. Both cores show sections with gaps in deposition or preservation, possible flood-stripping of peat during the pre-Holocene and mechanical disturbance by early Polynesians. The identification of prehistoric starch grains and other microremains of introduced Colocasia esculenta (taro) in both cores supports indirect evidence that the ditch systems of far northern New Zealand were used for the extensive cultivation of this crop. Copyright

  14. Surface Micellization Patterns of Quaternary Ammonium Surfactants on Mica

    E-print Network

    Aksay, Ilhan A.

    Surface Micellization Patterns of Quaternary Ammonium Surfactants on Mica Heather N. Patrick equilibrium structures of adsorbed films of quaternary ammonium surfactants on mica have been investigated never been reported on graphite. Mica is a model hydrophilic surface and has been previously used

  15. Late Quaternary history of Washington Land, North Greenland OLE BENNIKE

    E-print Network

    Ingólfsson, Ólafur

    Late Quaternary history of Washington Land, North Greenland OLE BENNIKE Bennike, O. 2002 (September): Late Quaternary history of Washington Land, North Greenland. Boreas, Vol. 31, 260­272. Oslo. ISSN 0300-9483. During the last glacial stage, Washington Land in western North Greenland was probably completely inun

  16. Quaternary seismo-tectonic activity of the Polochic Fault, Guatemala

    E-print Network

    Paris-Sud XI, Université de

    Quaternary seismo-tectonic activity of the Polochic Fault, Guatemala Christine Authemayou,1 transform boundary between the North American and Caribbean plates in Guatemala and the associated seismic), Quaternary seismo-tectonic activity of the Polochic Fault, Guatemala, J. Geophys. Res., 117, B07403, doi:10

  17. Sorption and desorption of quaternary amine cations on clays

    Microsoft Academic Search

    Z. Zhong Zhang; Donald L. Sparks; Noel C. Scrivner

    1993-01-01

    The authors have studied the sorption and desorption of three quaternary amines, namely, nonyltrimethylammonium, dodecyltrimethylammonium, and hexadecyltrimethylammonium, on homoionic Na- and K-montmorillonite using a titration procedure. More than 99% of all three of the quaternary amine cations studied were sorbed on the montmorillonite when the added amines were less than 70% of the cation-exchange capacity of the montmorillonite. Sorption of

  18. New mechanism of the formation of the uranium-titanium association in ores of paleovalley deposits

    Microsoft Academic Search

    S. F. Vinokurov; M. V. Nesterova

    2010-01-01

    Uranium-titanium association in ores of paleoval? ley deposits demonstrates space and genetic control of uranium mineralization by clastogene iron-titanium oxides (typically modified ilmenites); this link is more preferable than that to carbonaceous matter and iron sulfides. Orebearing uranium-titanium association is most widely abundant in paleovalley deposits of North America (sandstone type) located in alluvial sandstone enriched in iron-titanium oxides with

  19. Late Quaternary Surface Rupture Along the Seattle Fault Zone Near Bellevue, Washington

    NASA Astrophysics Data System (ADS)

    Sherrod, B. L.

    2002-12-01

    Fault strands in the eastern part of the Seattle fault zone (SFZ) ruptured the ground surface at least two times in late Quaternary time. Previous paleoseismic evidence for late Holocene surface faulting along the SFZ focused on north-dipping thrust faults between Seattle and Bremerton. In contrast, several exposures along the SFZ east of Seattle show surface rupture on south-dipping thrust faults. At Factoria, about 12 km east of Seattle, a ravine crossing the fault zone exposes proglacial lake sediments thrust over younger outwash to the north. Locally, this fault may account for a south side up topographic scarp. At Vasa Park on the west shore of Lake Sammamish about 16 km east of Seattle, recent excavations at two sites (RipRap and Blackberry) exposed a W to NNW-striking fault zone. At the RipRap site, NNW-striking subvertical dip-slip faults form a contact between glacial till and Miocene bedrock, and appear to accommodate bedding-plane slip in the steeply dipping till. The vertical faults merge upward with or are truncated by SW-dipping thrust faults in the overlying bedrock. A radiocarbon age on charcoal immediately overlying bedrock-derived colluvium suggests that the last event occurred between ~16,000 and ~4500 years BP. At the Blackberry trench about 200 m east of the RipRap site, Miocene volcanic mudstone and Quaternary glacial deposits are thrust northward over late Quaternary glacial deposits and a Holocene forest soil. Stratigraphic relationships suggest at least 3 m of horizontal motion and 2m of vertical motion during the last earthquake. A radiocarbon age on charcoal at the top of the buried soil indicates that the last event postdates 11550+/-40 years BP. Pending radiocarbon analyses will help refine the age of the last event. Thrusts cut by a Pleistocene (?) stream channel eroded into the hanging wall suggest at least one earlier episode of faulting.

  20. Soil-landscape development and late Quaternary environmental change in coastal Estremadura, Portugal

    NASA Astrophysics Data System (ADS)

    Daniels, Michael; Haws, Jonathan; Benedetti, Michael; Bicho, Nuno

    2015-04-01

    This poster integrates soil-landscape analysis with archaeological survey and paleoenvironmental reconstruction. Soils in surface and buried contexts in Estremadura, Portugal, provide evidence of landscape stability and instability, relative age relationships between landforms, and general paleoenvironmental conditions during the late Quaternary. These factors provide insight into the distribution and condition of Paleolithic archaeological sites and help understand the record of human settlement in the region. Late Pleistocene and Holocene dunes extend inland approximately 10 km from coastal source regions. Surface soils in Holocene dunes under maritime pine (Pinus pinaster) forest exhibit A, E, C/Bh and A, C horizon sequences and classify as Quartzipsamments. Surface soils in late Pleistocene dunes exhibit A, E, Bh, Bhs, Bs horizon sequences and classify as Haplorthods. Both Pleistocene and Holocene dunes commonly bury a heavily weathered soil formed in calcareous sandstone. The boundary between underlying buried soils and overlying surface soils is characterized by a lag deposit of medium to coarse, moderately-rounded gravels, underlain immediately by subsurface Bt and Bss horizons. The lag deposit and absence of buried A horizons both indicate intense and/or prolonged surface erosion prior to burial by late Quaternary dunes. Soil-geomorphic relationships therefore suggest at least two distinct episodes of dune emplacement and subsequent landscape stability following an extensive episode late Pleistocene landscape instability and soil erosion. A conceptual model of soil-landscape evolution through the late Quaternary and Holocene results from the integration of soil profile data, proxy paleoenvironmental data, and the partial record of human settled as revealed in the archaeological record.

  1. Quaternary geologic map of the Lookout Mountain 4° x 6° quadrangle, United States

    USGS Publications Warehouse

    State compilations by Miller, Robert A.; Maher, Stuart W.; Copeland, Charles W., Jr.; Rheams, Katherine F.; Neathery, Thorton L.; Gilliland, William A.; Friddell, Michael S.; Van Nostrand, Arnie K.; Wheeler, Walter H.; Holbrook, Drew F.; Bush, William V.; Edited and integrated by Richmond, Gerald M.; Fullerton, David S.; Digital edition by Bush, Charles A.

    1988-01-01

    This map is part of the Quaternary Geologic Atlas of the United States (I–1420). It was first published as a printed edition in 1988. The geologic data have now been captured digitally and are presented here along with images of the printed map sheet and component parts as PDF files. The Quaternary Geologic Map of the Lookout Mountain 4° x 6° Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the Earth. They make up the "ground" on which we walk, the "dirt" in which we dig foundations, and the "soil" in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale. In recent years, surficial deposits and materials have become the focus of much interest by scientists, environmentalists, governmental agencies, and the general public. They are the foundations of ecosystems, the materials that support plant growth and animal habitat, and the materials through which travels much of the water required for our agriculture, our industry, and our general well being. They also are materials that easily can become contaminated by pesticides, fertilizers, and toxic wastes. In this context, the value of the surficial geologic map is evident.

  2. Quaternary geologic map of the Mobile 4 degrees x 6 degrees quadrangle, United States

    USGS Publications Warehouse

    State compilations by Copeland, Charles W., Jr.; Rheams, K.F.; Neathery, T.L.; Gilliland, W.A.; Schmidt, Walter; Clark, W.C., Jr.; Pope, D.E.; edited and integrated by Richmond, Gerald Martin; Fullerton, David S.; Weide, David L.; Digital database by Bush, Charles A.

    1988-01-01

    This map is part of the Quaternary Geologic Atlas of the United States (I-1420). It was first published as a printed edition in 1988. The geologic data have now been captured digitally and are presented here along with images of the printed map sheet and component parts as PDF files. The Quaternary Geologic Map of the Mobile 4 degrees x 6 degrees Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the Earth. They make up the ground on which we walk, the dirt in which we dig foundations, and the soil in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale. In recent years, surficial deposits and materials have become the focus of much interest by scientists, environmentalists, governmental agencies, and the general public. They are the foundations of ecosystems, the materials that support plant growth and animal habitat, and the materials through which travels much of the water required for our agriculture, our industry, and our general well being. They also are materials that easily can become contaminated by pesticides, fertilizers, and toxic wastes. In this context, the value of the surficial geologic map

  3. Towards a quaternary time scale*1

    NASA Astrophysics Data System (ADS)

    Berggren, W. A.; Burckle, L. H.; Cita, M. B.; Cooke, H. B. S.; Funnell, B. M.; Gartner, S.; Hays, J. D.; Kennett, J. P.; Opdyke, N. D.; Pastouret, L.; Shackleton, N. J.; Takayanagi, Y.

    1980-05-01

    Nine first-appearance datums (FADs), twenty-three last-appearance datums (LADs), and three other micropaleontological datums are related to the magnetic-reversal, oxygen-isotope, and calcite-dissolution/coarse-fraction time scales to provide a preliminary basis for subdivision of the Quaternary in deep-sea sediments. The magnetic-reversal, oxygen-isotope, and calcite-dissolution/coarse-fraction scales have been correlated by determination on the same core materials, and absolute dates applied by {40K}/{40Ar} or 14C dating of materials in known positions on one or another of these scales. FADS and LADs have been determined in cores for which either a magnetic-reversal, oxygen-isotope, or calcite-dissolution/coarse-fraction scale has also been available. Altogether 3 FADs and 5 LADs based on diatoms, 4 FADs and 5 LADs based on calcareous nannoplankton, 1 FAD and 8 LADs based on radiolarians, 1 FAD and 5 LADs based on planktonic foraminifers, 2 acme datums, and 1 ratio reversal datum have been determined, and absolute dates inferred by interpolation from known dates on the reference time scales. Some of the FADs and LADs apply or are synchronous only over limited areas of the oceans; others appear to be synchronous throughout the oceans. The base of the Quaternary is set at the top of the Olduvai event at 1.7 my. Four FADs, twelve LADs, two acme datums, and one ratio reversal datum occur above the base of the Quaternary at an average rate of about 1 per 100,000 yr. Five FADs and twelve LADs are recognized in the 0.8-my interval between the top of the Olduvai event and the Gauss/Matuyama Boundary at 2.5 my at an average incidence of about 1 per 50,000 yr.

  4. New ternary and quaternary group IV tellurides

    SciTech Connect

    Keane, P.M.

    1992-01-01

    As a continuation of the interest in ternary transition-metal chalcogenides, the exploration of the ternary and quaternary Group IV tellurides, a class of compound largely unexplored, has been undertaken. For this particular system, the reactive flux method proves to be an invaluable crystallization and synthetic technique. These reactions have yielded several new phases, the majority of which represent unprecedented structure types. The compounds K[sub 4]M[sub 3]Te[sub 17] (M = Zr, Hf) contain one-dimensional [sup 1][sub [infinity

  5. Antibacterial activity of gemini quaternary ammonium salts.

    PubMed

    Ob??k, Ewa; Piecuch, Agata; Guz-Regner, Katarzyna; Dworniczek, Ewa

    2014-01-01

    A series of gemini quaternary ammonium salts (chlorides and bromides), with various hydrocarbon chain and spacer lengths, were tested. These compounds exhibited antibacterial activity against both Gram-positive and Gram-negative bacteria and were not mutagenic. The strongest antibacterial effect was observed for TMPG-10 Cl (against Pseudomonas aeruginosa ATCC 27853) and TMPG-12 Br (against Staphylococcus aureus ATCC 6538 and Escherichia coli ATCC 11229 and clinical ESBL(+) isolate 434) surfactants. These compounds inhibited the adhesion of Staphylococcus epidermidis ATCC 35984 to a polystyrene surface and eradicated biofilm formed by P. aeruginosa PAO1. The activity of studied compounds was dependent on hydrocarbon chain length. PMID:24236547

  6. Late-quaternary shift of fagus distribution

    Microsoft Academic Search

    Matsuo Tsukada

    1982-01-01

    Based on six resolved maps of its pollen frequency (dating 13,000, 10,000, 8,000, 6,000, 3,000 and 500 yr B.P.) at 33 sites\\u000a scattered almost throughout the Japanese Archipelago,Fagus shows principally a, unidirectional late-Quaternary shift in distribution from the southwest to the northeast. The maximum\\u000a areal coverage was from 10,000 to 7,000 years ago, although northeastern populations were not fully developed

  7. Fault-Bounded Late Neogene Sedimentary Deposits in the Santa Rosa Mountains, Southern CA: Constraints on the Evolution of the San Jacinto Fault

    NASA Astrophysics Data System (ADS)

    Matti, J. C.; Morton, D. M.; Cox, B. F.; Landis, G. P.; Langenheim, V. E.; Premo, W. R.; Kistler, R.; Budahn, J. R.

    2006-12-01

    In the Santa Rosa Mountains (SRM) on the W side of the Salton Trough, a late Neogene sedimentary sequence (Zosel sequence, ZS) in the hanging wall of the E-dipping Zosel normal fault (ZFHW) has implications for the geologic history of the southern San Andreas Fault (SAF) system. The upper conglomeratic part of the ZS records the culmination of slip on the ZF, which preceded strike-slip faulting on the right-lateral San Jacinto Fault (SJF) a few km to the W. The conglomerate is an alluvial-fan complex of fluvial, debris-flow, and rock-avalanche deposits that prograded NE over underlying paralic and marine deposits. Clasts are ?10m, and fluvial imbrications indicate mean streamflow trending ~N30E; paleocurrent indicators and clast compositions suggest sediment was derived mainly from granitoid terrains SW of the SRM. Deposition appears to have ceased by early Quaternary time: cosmogenic analysis of boulders from the eroded upper surface of the ZS indicates min and max exposure ages of 500Ka and 1.3Ma (Ne in qtz), 514Ka to 1.17Ma (Ne in hbl), and 647Ka to 1.158Ma (He). Granitoid clasts include distinctive texturally massive hbl- bio tonalite unlike any basement rock exposed in the SRM or in other footwall crystalline terranes directly to the W. The tonalite clasts are similar to bedrock in the White Wash (WW) area 24 km to the NW on the W side of the Clark strand of the SJF (SJFC). Initial Sr ratios for WW samples range from 0.70622 to 0.70631; ZS clasts range from 0.70615 to 0.70638. One sample from ZS and WW have identical light REE patterns that appear to be unique in the Peninsular Ranges batholith. U/Pb zircon ages for WW samples range from 96.6 to 98.2Ma while ZS clasts range from 95.8 to 98.7Ma. Based on these data, tonalite clasts in the ZS match tonalite now exposed in the WW area. We propose the following reconstruction: (1) From 6Ma to 1.2Ma, Zosel sediment is deposited near sea level as an alluvial-fan and fan-delta complex interfingering NE-ward with paralic and marine sediment. Deposition occurs on the ZFHW as it drops relative to footwall rocks, including the WW tonalite terrane. (2) ZS deposition ceases by1.2Ma, as right slip on SJFC succeeds detachment-style normal slip on the ZF. (3) Subsequently, complex en-echelon fault relations within the evolving SJF zone produce large vertical and horizontal displacements in the SRM region. Extensional collapse of the WW terrane and neighboring areas occurs between the right-stepping Coyote Creek strand and SJFC, while contraction across a regional left step between the San Andreas and San Jacinto faults simultaneously uplifts the main body of the SRM, including marine ZS now situated 600m above sea level. This implies that the ZF hanging wall rose more than 600m relative to sea level, apparently buoyed up together with underlying footwall crystalline rocks. (4) Relative vertical displacement between the SRM core and its downdropped W flanks was accommodated by down-to-the-SW slip on the Santa Rosa Fault and associated listric mega-landslide blocks N and NW of Clark Lake Valley (CLV). These events downdropped CLV and produced the high-relief W face of the SRM. (5) The unique WW tonalite terrane is displaced dextrally ~24km, leaving behind a cross-fault counterpart presumably concealed deep beneath NW CLV. This apparently represents total displacement on all strands of the SJF zone since ~1.2Ma, implying a minimum slip rate of about 20mm/yr.

  8. An investigation of flows and losses within the alluvial sands of ephemeral rivers in Zimbabwe

    NASA Astrophysics Data System (ADS)

    Mansell, M. G.; Hussey, S. W.

    2005-11-01

    Ephemeral rivers are common hydrological features in Southern Africa where periods of up to 9 months occur with no significant rainfall. In many cases, they have well-defined channels in-filled with alluvial sands in which significant quantities of water flow, even when the surface flow has ceased. This water resource is commonly exploited either by shallow pits dug in the sand or by well-points, infiltration galleries or collector wells in the river bank and provides a valuable, readily available supply for local people [Hussey, S.W., 1997. Small-scale sand abstraction systems, 23rd WEDC Conference Water and Sanitation for All, Durban, WEDC]. The processes involved in the flow in these so-called 'sand rivers' present interesting hydrological and hydraulic questions. From a hydrological perspective, it could be argued that the flow in the alluvium is an extension of the surface flow and could be estimated by extrapolating the surface flow recession curve. Hydraulically, the flow can be visualised as a closed conduit, which has a slope to its base approximating to the sand surface but more irregular. Although the flow may follow the well-known Darcy formula, the conventional methods of analysis of groundwater systems may not apply as they normally assume horizontally bedded deposits of infinite lateral extent. This paper presents the results of a study of four sites in the Matabeleland Province of Zimbabwe over a period of about 3 years. At each site, water level readings were recorded from a number of piezometers in the alluvium together with an estimation of the bedrock profile. The velocity of flow was estimated from the slope of the phreatic surface as well as from salt dilution experiments. A simple model has been developed based on a 'closed conduit' concept, which estimates the recession of the water levels and flow rates in the alluvium, including the effects of evaporation from the sand surface as well as recharge by intermittent rainfall during the dry season. This model has been calibrated and validated against the field observations from the four sites.

  9. Deducing Weathering Processes Using Silicon Isotopes in the Ganges Alluvial Plain, India

    NASA Astrophysics Data System (ADS)

    Frings, P.; De La Rocha, C. L.; Fontorbe, G.; Chakrapani, G.; Clymans, W.; Conley, D. J.

    2014-12-01

    The Ganges Alluvial Plain ('GAP') is the sedimentary infill of the foreland basin created during Himalayan orogeny. Freshly eroded material from the Himalaya and southern cratonic tributaries is deposited into a system with long water-sediment interaction times, creating potential for further generation of river weathering fluxes. To quantify weathering processes in the GAP, 51 sites including all major tributaries were sampled in a September 2013 campaign and analysed for major and minor ions, Ge/Si ratios and ?30Si, ?13C and ?18O. Net dissolved Si (DSi) and major cation yields are 2 to 5 times lower in the GAP than the Himalaya, and at a whole basin scale approximate the global average, indicating that the plain apparently moderates the efficiency of Himalayan weathering rates. Mainstem ?30Si spans 0.81 to 1.93‰ (see figure) and gives the impression of a system buffered to moderate DSi and ?30Si. Ge/Si ratios (µmol/mol) are higher than expected in the Himalaya (>3), reflecting input of Ge-enriched water from hot springs, and decline to ~1.4 in the GAP. For the Himalayan sourced rivers, ?30Si increases with distance from the Himalayan front, and can not be explained entirely by conservative mixing with higher ?30Si peninsular and GAP streams. To a first degree, the ?30Si data suggest incorporation of Si into secondary minerals as the key fractionating process, and that this occurs both in situ during initial weathering and progressively in the GAP. Partitioning of solutes between sources is complicated in the GAP. Consistent with previous work, carbonate weathering dominates the ion fluxes, but with substantial contributions from saline/alkaline soil salts, the chlorination of wastewater and highly variable rainfall chemistry. Due to these contributions, precisely inferring the input from silicate weathering is difficult. We introduce a novel method to infer silicate-weathering rates that exploits the fractionation of Si during clay formation to account for the loss of DSi from solution.

  10. Nest survival of forest birds in the Mississippi Alluvial Valley

    USGS Publications Warehouse

    Twedt, D.J.; Wilson, R.R.; Henne-Kerr, J.L.; Hamilton, R.B.

    2001-01-01

    In the Mississippi Alluvial Valley, flood control has led to a drastic reduction in the area of forest habitat and altered the patchwork of forest cover types. Silvicultural management of the remaining fragmented forests has changed to reflect the altered hydrology of the forests, current economic conditions of the area, and demand for forest products. Because forest type and silvicultural management impact forest birds, differences in avian productivity within these forests directly impact bird conservation. To assist in conservation planning, we evaluated daily nest survival, nest predation rates, and brood parasitism rates of forest birds in relation to different forest cover types and silvicultural management strategies within this floodplain. Within bottomland hardwood forests, nest success of blue-gray gnatcatcher (Polioptila caerulea, 13%), eastern towhee (Pipilo erythrophthalmus, 28%), indigo bunting (Passerina cyanea, 18%), northern cardinal (Cardinalis cardinalis, 22%), and yellow-billed cuckoo (Coccyzus americanus, 18%) did not differ from that within intensively managed cottonwood plantations. However, average daily survival of 542 open-cup nests of 19 bird species in bottomland hardwoods (0.9516 + 0.0028, -27% nest success) was greater than that of 543 nests of 18 species in cotlonwood plantations (0.9298 + 0.0035, -15% nest success). Differences in daily nest survival rates likely resulted from a combination of differences in the predator community--particularly fire ants (Solenopsis invicta)--and a marked difference in species composition of birds breeding within these 2 forest types. At least 39% of nests in bottomland hardwood forests and 65% of nests in cottonwood plantations were depredated. Rates of parasitism by brown-headed cowbirds (Molothrus ater) were greater in managed cottonwoods (24%) than in bottomland hardwoods (9%). Nest success in planted cottonwood plantations for 18 species combined (-14%), and for yellow-breasted chat (Icteria vimns, 7%), eastern towhee (14%), indigo bunting (14%), and northern cardinal (17%) did not differ from nest success in cottonwood plantations that were coppiced from root sprouts following pulpwood harvest. Within bottomland hardwood forests, uneven-aged group-selection timber harvest reduced the combined daily nest survival of all species from 0.958 to 0.938, which reduced nest success by about 14%. Specifically, timber harvest reduced nest success of species that nest in the forest midstory and canopy, such as Acadian flycatcher (Empidonax virescens)--from 32% before harvest to 14% after harvest. Conversely, those species that nest primarily in the shrubby understory--such as northern cardinal--were not affected by timber harvest and maintained an overall nest success of about 33%. Thus, birds nesting in the understory of bottomland hardwood forests are not adversely impacted by selective timber harvest, but there is a short-term reduction in nest success for birds that nest in the canopy and midstory.

  11. Geologically based model of heterogeneous hydraulic conductivity in an alluvial setting

    NASA Astrophysics Data System (ADS)

    Fogg, Graham E.; Noyes, Charles D.; Carle, Steven F.

    Information on sediment texture and spatial continuity are inherent to sedimentary depositional facies descriptions, which are therefore potentially good predictors of spatially varying hydraulic conductivity (K). Analysis of complex alluvial heterogeneity in Livermore Valley, California, USA, using relatively abundant core descriptions and field pumping-test data, demonstrates a depositional-facies approach to characterization of subsurface heterogeneity. Conventional textural classifications of the core show a poor correlation with K; however, further refinement of the textural classifications into channel, levee, debris-flow, and flood-plain depositional facies reveals a systematic framework for spatial modeling of K. This geologic framework shows that most of the system is composed of very low-K flood-plain materials, and that the K measurements predominantly represent the other, higher-K facies. Joint interpretation of both the K and geologic data shows that spatial distribution of K in this system could not be adequately modeled without geologic data and analysis. Furthermore, it appears that K should not be assumed to be log-normally distributed, except perhaps within each facies. Markov chain modeling of transition probability, representing spatial correlation within and among the facies, captures the relevant geologic features while highlighting a new approach for statistical characterization of hydrofacies spatial variability. The presence of fining-upward facies sequences, cross correlation between facies, as well as other geologic attributes captured by the Markov chains provoke questions about the suitability of conventional geostatistical approaches based on variograms or covariances for modeling geologic heterogeneity. Résumé Les informations sur la texture des sédiments et leur continuité spatiale font partie des descriptions de faciès sédimentaires de dépôt. Par conséquent, ces descriptions sont d'excellents prédicteurs potentiels des variations spatiales de la conductivité hydraulique (K). L'analyse de l'hétérogénéité des alluvions complexes de la vallée de Livermore (Californie, États-Unis), sur la base de descriptions de carottes relativement nombreuses et de données d'essais de pompage, montre que l'hétérogénéité souterraine peut être caractérisée par une approche des faciès de dépôt. Des classifications conventionnelles de la texture de la carotte montrent une corrélation médiocre avec K; toutefois, une amélioration ultérieure des classifications de texture en faciès de dépôt de chenal, de levée d'inondation, de coulée boueuse et de plaine d'inondation a fourni un cadre systématique pour une modélisation spatiale de K. Ce cadre géologique montre que le système est composé pour l'essentiel par des matériaux d'inondation à très faible perméabilité ceci laisse envisager qu'on ne peut pas supposer que K suit une distribution log-normal, sauf peut-être à l'intérieur de chaque faciès. Une modélisation par chaîne de Markov de la probabilité de passage, représentant la corrélation spatiale dans les faciès et entre eux, prend en compte les faits géologiques intéressants tout en fournissant une approche nouvelle pour une caractérisation statistique de la variabilité spatiale des faciès. La présence de séquences à faciès tronqués vers le haut, d'une corrélation croisée entre faciès, ainsi que d'autres caractères géologiques pris en compte par les chaînes de Markov conduisent à se poser des questions sur l'adéquation des approches géostatistiques conventionnelles utilisant les variogrammes ou les covariances pour modéliser l'hétérogénéité géologique. Resumen La información respecto a la textura de los sedimentos y la continuidad espacial es inherente a las descripciones de las facies deposicionales sedimentarias. De este modo, estas descripciones se convierten en excelentes predictores potenciales de las variaciones espaciales de la conductividad hidráulica (K). El análisis de la heterogeneidad en un aluvial en el Valle de L

  12. Late Quaternary mass-wasting records in the actively uplifting Pa-chang catchment, southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Hsieh, Meng-Long; Ching, Kuo-En; Chyi, Shyh-Jeng; Kang, Su-Chen; Chou, Chun-Yen

    2014-07-01

    Although dominated by erosion over long term, the tectonically active mountains of Taiwan commonly contain thick landslide and debris-flow gravels capping hillslopes or forming alluvial terraces. These deposits and their associated landforms serve to study ancient mass-wasting histories and their controls on fluvial processes. This study focuses on the Pa-chang River draining the < 2000 m high Ali-shan area in southwestern Taiwan (current tectonic uplift: 5-8 mm yr- 1). Although small (catchment area: 83 km2), the Pa-chang exhibits one of the largest alluvial terraces in Taiwan, which stretches from the outlet of the catchment for 9 km along the river and comprises fluvial and debris-flow gravels up to 150 m thick. Totally 55 radiocarbon dates have been obtained, tracing the mass-wasting records back to 14.8 ka. The largest events, which created the studied major terraces, occurred in 10.0-11.3 and 8.7-9.4 ka. These events are synchronous with the formation of some regionally largest alluvial terraces in Taiwan, and may have been triggered by the frequent heavy rains associated with the early Holocene East Asian summer-monsoon maximum. More mass-wasting events have been dated at ~ 5.4, ~ 1.9, 1.2-1.7, 0.7-0.9, ~ 0.6, and < 0.3 ka. The vast supply of sediment from the recorded mass-wasting events not only caused river aggradation but also regulated the subsequent incision by forming boulder armors. As a result, the bedrock incision in the upper part of the catchment has been negligible since the early Holocene debris-flow deposition. The incision rates increase to the downstream direction as the size and concentration of boulders reduce. Still, the 14.8 ka-averaged bedrock incision rate (< 4.5 mm yr- 1) at the catchment outlet is lower than the current uplift rate (6 mm yr- 1). At the same site, however, the bedrock incision rate is 23 mm yr- 1 averaged over the past 0.6 ka. Even higher rates of incision (> 50 mm yr- 1) are detected further downstream after the recent gravel mining. The fact that the obtained bedrock incision rates and patterns are decoupled with the tectonic uplift advises caution in using short-term erosion data to interpret the tectonics of the Taiwan's mountains.

  13. Application of time-domain electromagnetic method in mapping saltwater intrusion of a coastal alluvial aquifer, North Oman

    NASA Astrophysics Data System (ADS)

    El-Kaliouby, Hesham; Abdalla, Osman

    2015-04-01

    One-third of the population of Oman depends on the groundwater extracted from the alluvium deposits located along the coast of the Gulf of Oman. However, groundwater depletion and seawater intrusion constitute major challenges along the coastal water accumulations in Oman. The objective of this study is to locate the extent of seawater intrusion and to map the shallow alluvial aquifer in the region, where water accumulates from the rain or the flooding at AlKhod dam. In order to assess the effect of groundwater infiltration, which recharges the aquifer and fights the seawater invasion, a quantitative approach for the groundwater quality and distribution is required to provide reasonable knowledge on the spatial distribution of the aquifers, their thickness and the type of sediments. When groundwater wells and their subsurface geologic and electrical logs are not available or not deep enough, surface geophysical surveys can be considered due to their low cost and short acquisition time. The application of time-domain electromagnetic (TDEM) method in Al-Khod area, Oman has proven to be a successful tool in mapping the fresh/saline water interface and for locating the depth of fresh water aquifer. The depths and inland extents of the saline zone were mapped along three N-S TDEM profiles. The depths to the freshwater table and saline interface calculated from TDEM closely match the available well data.

  14. An evaluation strategy for conservation goals of the Mississippi Alluvial Valley

    USGS Publications Warehouse

    Twedt, D.J.; Hamel, P.B.; Cooper, R.J.; Woodrey, M.S.

    2000-01-01

    The population goals and habitat objectives established by the Mississippi Alluvial Valley Migratory Bird Initiative are based on several unverified assumptions. We have developed an evaluation strategy that identifies research needed to verify these assumptions. We also have outlined a monitoring strategy designed to track progress toward achieving habitat objectives and population goals.

  15. Reference Conditions for Old-Growth Redwood Restoration on Alluvial Flats

    E-print Network

    Standiford, Richard B.

    -growth coast redwood stands. Tree size parameters and occurrences of distinctive features (e.g., burls, goose251 Reference Conditions for Old-Growth Redwood Restoration on Alluvial Flats Christa M. Dagley1 sizes was similar between study sites. Redwood density ranged from 118 to 148 trees ha-1 and upper

  16. Natural arsenic contamination of Holocene alluvial aquifers by linked tectonic, weathering, and microbial processes

    Microsoft Academic Search

    J. A. Saunders; M.-K. Lee; A. Uddin; S. Mohammad; Richard T. Wilkin; Mostafa Fayek; Nic E. Korte

    2005-01-01

    Linked tectonic, geochemical, and biologic processes lead to natural arsenic contamination of groundwater in Holocene alluvial aquifers, which are the main threat to human health around the world. These groundwaters are commonly found a long distance from their ultimate source of arsenic, where chemical weathering of As-bearing minerals occurs. We propose a “GBH-As” model that ties together all of the

  17. HYDRAULIC ANALYSIS OF BASE-FLOW AND BANK STORAGE IN ALLUVIAL STREAMS

    EPA Science Inventory

    This paper presents analytical solutions, which describe the effect of time-variable net recharge (net accretion to water table) and bank storage in alluvial aquifers on the sustenance of stream flows during storm and inter-storm events. The solutions relate the stream discharge,...

  18. Occurrence of Arsenic in Ground Water in the Choushui River Alluvial Fan, Taiwan

    Microsoft Academic Search

    Chen-Wuing Liu; Sheng-Wei Wang; Cheng-Shin Jang; Kao-Hong Lin

    2006-01-01

    An investigation of shallow ground water quality revealed that high arsenic (As) concentrations were found in both aquifers and aquitards in the southern Choushui River alluvial fan of Taiwan. A total of 655 geological core samples from 13 drilling wells were col- lected and analyzed. High As contents were found primarily in aqui- tards, to a maximum of 590 mg\\/kg.

  19. Mobility of lead, zinc and cadmium in alluvial soils heavily polluted by smelting industry

    Microsoft Academic Search

    A. Van?k; L. Bor?vka; O. Drábek; M. Mihaljevi?; M. Komárek

    In order to determine the mobility of Pb, Zn and Cd in soils from the P?íbram region (Czech Republic) heavily conta- minated by metallurgy, two profiles of alluvial soils were closely studied. Total contents of heavy metals were deter - mined aer digestion with a mixture of HF and HClO 4 . Heavy metal mobility was assessed using the mobility

  20. INFLUENCE OF SEDIMENT SUPPLY, LITHOLOGY, AND WOOD DEBRIS ON THE DISTRIBUTION OF BEDROCK AND ALLUVIAL CHANNELS

    EPA Science Inventory

    Field surveys in the Willapa River basin, Washington State, indicate that the drainage area?channel slope threshold describing the distribution of bedrock and alluvial channels is influenced by the underlying lithology and that local variations in sediment supply can overwhelm ba...

  1. Modeling of Reactive Transport of Nitrate in a Heterogeneous Alluvial Fan Aquifer, San Joaquin Valley, California

    Microsoft Academic Search

    C. T. Green; S. P. Phillips

    2005-01-01

    Fate of nitrate in an alluvial fan aquifer in the San Joaquin Valley, California, was investigated with combined laboratory analyses, field measurements, geostatistics, and flow and reactive transport modeling. In the summer of 2003, groundwater wells and lysimeters were installed along a 1-km transect extending upgradient from the Merced River through an unfarmed riparian zone, a corn field, and an

  2. Arsenic enrichment in groundwater of the alluvial aquifers in Bangladesh: an overview

    Microsoft Academic Search

    K. Matin Ahmed; Prosun Bhattacharya; M. Aziz Hasan; S. Humayun Akhter; S. M. Mahbub Alam; M. A. Hossain Bhuyian; M. Badrul Imam; Aftab A Khan; Ondra Sracek

    2004-01-01

    Arsenic in the groundwater of Bangladesh is a serious natural calamity and a public health hazard. Most groundwater from the shallow alluvial aquifers (<150 m), particularly in the Holocene plain lands, are vulnerable to As-enrichment. Delta plains and flood plains of the Ganges–Brahmaputra river system are moderately to severely enriched and more than 60% of the tube wells are affected.

  3. Implementation of Drainage Water Management in Open Ditch Drainage Systems of the Mississippi Alluvial Valley

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increased riverine nutrients linked to agricultural activities in the Mississippi River Basin have contributed to degraded surface waters within the basin as well as to the hypoxic zone along the Louisiana Gulf coast. In the Mississippi Alluvial Valley (MAV), these nutrients are transported from agr...

  4. Response of active tectonics on the alluvial Baghmati River, Himalayan foreland basin, eastern India

    Microsoft Academic Search

    Vikrant Jain; R. Sinha

    2005-01-01

    Active tectonics in a basin plays an important role in controlling a fluvial system through the change in channel slope. The Baghmati, an anabranching, foothills-fed river system, draining the plains of north Bihar in eastern India has responded to ongoing tectonic deformation in the basin. The relatively flat alluvial plains are traversed by several active subsurface faults, which divide the

  5. Isotopic evidence for climatic influence on alluvial-fan development in Death Valley, California

    Microsoft Academic Search

    Ronald I. Dorn; M. J. DeNiro; H. O. Ajie

    1987-01-01

    At least three semiarid to arid cycles are recorded by ..delta..¹³C values of organic matter in layers of rock varnishes on surfaces of Hanaupah Canyon and Johnson Canyon alluvial fans, Death Valley, California. These isotopic paleoenvironmental signals are interpreted as indicating major periods of fan aggradation during relatively more humid periods and fan entrenchment during subsequent lengthy arid periods.

  6. Environmental impacts on the hydrology of ephemeral streams and alluvial aquifers

    Microsoft Academic Search

    C. Kuells; V. Marx; A. Bittner; R. Ellmies; M. Seely

    2009-01-01

    In arid and semi-arid regions alluvial groundwater resources of ephemeral streams are highly important for water supplies and ecosystems. Recent projects have studied processes of indirect recharge in situ and in detail (Dahan et al., 2008; Klaus et al., 2008). Still, little is known about the vulnerability of these aquifers to environmental impacts like surface dam constructions, land-use changes and

  7. Hydrologic interactions of stream channels with their alluvial system in northeastern Wyoming

    Microsoft Academic Search

    V. R. Hasfurther; R. C. Miller; L. B. Wesche

    1980-01-01

    Perennial and ephemeral stream channels were investigated among three study sites in northeastern Wyoming to determine the interaction of the stream with the alluvial system and its surroundings. Hydrographs of the surface stream and ground water wells in the valley fill material (alluvium) are correlated with the geology, water quality and vegetation. A water budget analysis and soil moisture measurements

  8. Comparison of subsurface and surface runoff phosphorus transport rates in alluvial floodplains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phosphorus (P) loading to streams can occur by both surface runoff and subsurface transport. Although surface runoff is often considered the dominant pathway, groundwater P concentrations in alluvial aquifers can be significant, especially in preferential flow paths (PFPs). The objectives of this re...

  9. Determinism in Fish Assemblages of Floodplain Lakes of the Vastly Disturbed Mississippi Alluvial Valley

    Microsoft Academic Search

    L. E. Miranda; G. M. Lucas

    2004-01-01

    The Mississippi Alluvial Valley between southern Illinois and southern Louisiana contains hundreds of floodplain lakes, most of which have been adversely affected by landscape modifications used to control flooding and support agriculture. We examined fish assemblages in lakes of this region to determine whether deterministic patterns developed in relation to prominent abiotic lake characteristics and to explore whether relevant abiotic

  10. The role of Quaternary environmental change in plant macroevolution: the exception or the rule?

    Microsoft Academic Search

    Katherine J. Willis; Karl J. Niklas

    2004-01-01

    The Quaternary has been described as an important time for genetic diversification and speciation. This is based on the premise that Quaternary climatic conditions fostered the isolation of populations and, in some instances, allopatric speciation. However, the 'Quaternary Ice-Age speciation model' rests on two key assumptions: (i) that biotic responses to climate change during the Quaternary were significantly different from

  11. Detection and Mapping of Sedimentary Features on Alluvial Fans Using High-Resolution Overhead Thermal Imaging

    NASA Astrophysics Data System (ADS)

    Hardgrove, C. J.; Moersch, J. E.; Whisner, S.

    2008-12-01

    In this study we evaluate the utility of thermal imagery for revealing geomorphic features and evidence of sedimentary processes on the surfaces of alluvial fans. Prior studies of alluvial fans have made extensive use of visible imagery and traditional field-based mapping techniques to identify surface geomorphic features and sedimentary processes. Here we present a comparison of features mapped using thermal images acquired from the ground, a light aircraft (altitude ~5000 ft, resolution ~2 m/pixel) and ASTER satellite imagery (resolution 90 m/pixel), to a preexisting ground-based map of features on an example alluvial fan in Owens Valley, California. Thermal images from a light aircraft were acquired at several times of day to determine how the surface temperatures of the alluvial fan rise and fall throughout a diurnal cycle. We have also acquired thermal images of the same fan from the ground at 5 minute intervals over the course of a full diurnal cycle. ASTER thermal data also covers the Owens Valley, and was used to determine if this technique can be used from orbit at significantly lower resolution (90 m/pixel). In an arid climate with low vegetation cover, the temperature of a surface at any given time of day is a complex function of many parameters, including slope, azimuth, composition, degree of induration, and grain size. By analyzing the temperatures on the surface of an alluvial fan with comparable slopes, azimuth, and composition, we make estimates of the relative particle size or degree of induration. We utilize the fact that several sedimentary processes acting on the surface of alluvial fans sort particles by size. For example, both debris flow and channelized flow processes can form linear features of large and small clasts. Therefore, thermal imagery could be expected to reveal evidence of these processes at the surfaces of alluvial fans in the form of spatial patterns of surface thermal properties. Process-related sedimentary features, such as clast-rich and clast-poor debris flows, debris-flow levees, and the change in particle size at the toe of the fan are all clearly revealed in the aerial thermal images of the Dolomite Fan in Owens Valley, California. The locations of these features in the thermal imagery match the locations of the features as mapped using traditional ground-based field sedimentology techniques by Blair and McPherson (1998). All debris flows that are exposed at the fan surface are evident in the aerial thermal imagery, including those that have been heavily weathered and are difficult to observe in visible aerial or orbital imagery. ASTER satellite thermal image data does not show the same sedimentary features as our aerial thermal images, presumably due to the significantly poorer spatial resolution of the satellite data. Our aerial thermal imagery suggests that higher resolution satellite data from a future satellite experiment could be used to detect sedimentary processes on alluvial fans anywhere on Earth. High resolution thermal imagery from above can be used to provide preliminary reconnaissance of an alluvial fan, suggest what processes have most recently acted on the surface of the fan, and to prioritize sites for detailed study on the ground. Future work will expand our database of alluvial fans and the list of process-related surface features that can be identified with thermal imagery.

  12. Quaternary glaciation of tibet: The geological evidence

    NASA Astrophysics Data System (ADS)

    Derbyshire, Edward; Shi Yafeng; Li Jijun; Zheng Benxing; Li Shijie; Wang Jingtai

    The question of the number and extent of Pleistocene glaciations on the Qinghai-Xizang (Tibet) Plateau remains contentious. There has been considerable research activity in Tibet by Chinese scientists since the late 1950s and their principal findings, including data on glacial and periglacial geomorphology, sedimentology, tectonics, stratigraphy and lake history, have been used to reconstruct ice margins and palaeosnowlines. Three, and in places, four distinct glaciations have been recognised, the most extensive occurring in the later Middle Pleistocene. Valley and piedmont glacial systems, with some mountain ice caps and a small ice sheet on the upper reaches of the Huang He, have been recognised but there is no evidence of a single Tibetan ice sheet. As the Plateau and the Himalaya-Karakoram underwent accelerating uplift through the Quaternary, there occurred progressive desiccation in the interior as the influx of Indian Ocean moisture was constrained. Equilibrium line elevations in the last glacial maximum were 4000 m in the south, east and northeast Plateau margins, rising to 5500 m in the northwest interior. The heat island provided by the Plateau, the progressive reduction in precipitation most marked during the glacials, and the strong southeast to northwest precipitation gradients, produced a glacier distribution pattern dominated by the trans-Tibetan mountain ranges. Tectonics and periglacial (including aeolian) processes have played an equal role with glaciation in generating the Plateau's Quaternary sedimentary succession.

  13. Factors controlling Pliocene-Quaternary sedimentation on the Gulf of Cadiz Continental Slope, Spain

    SciTech Connect

    Baraza, J.; Maldonado, A. (Ciencia del Mar, Barcelona (Spain)); Nelson, C.H. (Geological Survey, Menlo Park, CA (USA))

    1990-05-01

    The Pliocene-Quaternary sedimentation on the Gulf of Cadiz continental slope records an interaction between the tectonics responsible for a complex bathymetry, and the Mediterranean outflow undercurrent developed after the opening of the Gibraltar Strait at the end of the Miocene. During periods of low sea level, sedimentation was controlled mainly by changes in the sediment supply from the various rivers that feed the area. During high sea level, periods like the present, deposition is controlled mainly by the Mediterranean undercurrent. The Mediterranean undercurrent flows out from the Strait of Gibraltar toward the northwest and impinges on the Cadiz continental slope at 300- to 500-m depths. Flows are fastest near the Strait of Gibraltar (as much as 200 m/sec) and slow to 10-20 m/sec westward Portugal. The gradual decrease in undercurrent speed from the Strait of Gibraltar to the center of the Gulf of Cadiz results in a westward change from erosional to depositional characteristics on the upper continental slope. Erosion in the southeastern part of the Gulf is characterized by exposed bed rock on the sea floor and by erosional truncation of reflectors on sea-floor slopes. In contrast, several prograding shelf-break types and slope configurations occur in the west, showing the influence of tectonic subsidence, diapir uplift and sediment supply on the Pliocene-Quaternary sedimentation. At middle slope depths, high-energy depositional features, such as cut-and-fill structures, are observed in seismic profiles. Energy decreasing bed-form fields, from east to west, are shown in profiles and sonographic of the most sufficial units on the deep platforms. In addition, sediment drift bodies deposit against basement diapiric ridges near the canyon-ridge central area.

  14. Infiltration of atrazine and metabolites from a stream to an alluvial aquifer

    USGS Publications Warehouse

    Squillace, P.J.; Burkart, M.R.; Simpkins, W.W.

    1997-01-01

    The infiltration of atrazine, deethylatrazine, and deisopropylatrozine from Walnut Creek, a tributary stream, to the alluvial valley aquifer along the South Skunk River in central Iowa occurred where the stream transects the river's flood plain. A preliminary estimate indicated that the infiltration was significant and warrants further investigation. Infiltration was estimated by measuring the loss of stream discharge in Walnut Creek and the concentrations of atrazine and its metabolites deethylatrazine and deisopropylatrazine, in ground water 1 m beneath the streambed. Infiltration was estimated before application of agrichemicals to the fields during a dry period on April 7, 1994, and after application of agrichemicals during a period of small runoff on June 8, 1994. On April 7, the flux of atrazine, deethylatrazine, and deisopropylatrazine from Walnut Creek into the alluvial valley aquifer ranged from less than 10 to 60 (??g/d)/m2, whereas on June 8 an increased flux ranged from 270 to 3060 (??g/d)/m2. By way of comparison, the calculated fluxes of atrazine beneath Walnut Creek, for these two dates, were two to five orders of magnitude greater than an estimated flux of atrazine to ground water caused by leaching from a field on a per-unit-area basis. Furthermore, the unit-area flux rates of water from Walnut Creek to the alluvial valley aquifer were about three orders of magnitude greater than estimated recharge to the alluvial aquifer from precipitation. The large flux of chemicals from Walnut Creek to the alluvial valley aquifer was due in part to the conductive streambed and rather fast ground water velocities; average vertical hydraulic conductivity through the streambed was calculated as 35 and 90 m/d for the two sampling dates, and estimated ground water velocities ranged from 1 to 5 m/d.

  15. Quaternary geologic map of the Hudson River 4 degree x 6 degree quadrangle, United States and Canada

    USGS Publications Warehouse

    State and province compilations by Fullerton, David S.; Sevon, William D.; Muller, Ernest H.; Judson, Sheldon; Black, Robert F.; Wagner, Phillip W.; Hartshorn, Joseph H.; Chapman, William F.; Cowan, William D.; edited and integrated by Fullerton, David S.

    1992-01-01

    The Quaternary Geologic Map of the Hudson River 4? x 6? Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the earth. They make up the 'ground' on which we walk, the 'dirt' in which we dig foundations, and the 'soil' in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale.

  16. Palaeogene lacustrine record in Mallorca (NW Mediterranean, Spain): depositional, palaeogeographic and palaeoclimatic implications for the ancient southeastern Iberian margin

    Microsoft Academic Search

    Emilio Ramos; Llu??s Cabrera; Hans W Hagemann; Walter Pickel; Isabel Zamarreño

    2001-01-01

    Middle Bartonian (Middl1e Eocene) and Chattian (Upper Oligocene) lacustrine and alluvial-lacustrine successions exist in Mallorca (northwestern Mediterranean). They yield a significant palaeobiological record comprising fossil land plants and vertebrates and constitute the best available depositional record for a preliminary palaeogeographic and palaeoclimatic analysis of the northeastern part of the Palaeogene southern Iberian Margin (western Tethys). Both lacustrine systems developed under

  17. Preliminary study of quaternary faulting on the east side of Bare Mountain, Nye County, Nevada

    SciTech Connect

    Reheis, M.C.

    1986-12-31

    Active faults bound the east side of Bare Mountain. Geomorphic features, stratigraphy, and soil development indicate that two 3-km-long segments of the range-front fault probably last moved in Holocene or late Pleistocene time. Other segments of the fault have been quiescent since the late Pleistocene. Both late Pleistocene and Holocene deposits bury many faults east of the northern end of Bare Mountain. Two prospect pits on the range-front fault reveal evidence of recurrent late Quaternary movements. Both older and younger deposits in one pit are faulted, but fractures in the older unit do not extend up into the younger unit. Based on soil development, the older and younger fault episodes respectively are probably late Pleistocene and Holocene in age. Another pit shows carbonate-cemented fractures with slickensides in a late Pleistocene deposit, suggesting at least two late Pleistocene or Holocene fault movements. Middle to early Pleistocene and Tertiary deposits show evidence of recurrent faulting in many locations. Faults in these deposits are pervaded by secondary CaCO{sub 3} and silica that commonly exhibit slickensides.

  18. Clast-contact conglomerates in submarine canyons: possible subaqueous sieve deposits

    SciTech Connect

    Fitzgerald, M.S.

    1987-05-01

    Thick, coarse, clast-contact conglomerates in submarine canyon fill have previously been attributed to rock-fall, grain-flow, or winnowing processes. However, these processes do not adequately explain some thick conglomeratic sequences. The proposed process of subaqueous sieve deposition could account for these clast-contact conglomerates. Subaerial sieve deposition has been documented on small-scale fan models and on alluvial fans. A subaerial sieve deposit begins as a debris flow which at some point freezes up. The matrix is then lost by subsequent filtration or outflow, and the emplacement of a clast-contact gravel ensues. A subaqueous sieve deposit would be slightly modified in that the matrix would not be lost by filtration into the submarine canyon floor, but rather by outflow at the terminus of the lobe immediately after deposition, or possibly from the top and/or sides of the freezing flow mass during transport. Besides forming in submarine canyons, subaqueous sieve deposits might also occur in paralic, submarine fan channel, and base-of-the-slope settings. In substantiating the existence of subaqueous sieve deposits, the sedimentary structures and grain-size data from recent sieve deposits on alluvial fans are compared to those of ancient submarine canyon deposits. Numerous similarities are found supporting this new method of deposition. Some discrepancies are encountered, but these are expected due to modifications caused by an aqueous medium.

  19. Antimicrobial Polymeric Materials with Quaternary Ammonium and Phosphonium Salts

    PubMed Central

    Xue, Yan; Xiao, Huining; Zhang, Yi

    2015-01-01

    Polymeric materials containing quaternary ammonium and/or phosphonium salts have been extensively studied and applied to a variety of antimicrobial-relevant areas. With various architectures, polymeric quaternary ammonium/phosphonium salts were prepared using different approaches, exhibiting different antimicrobial activities and potential applications. This review focuses on the state of the art of antimicrobial polymers with quaternary ammonium/phosphonium salts. In particular, it discusses the structure and synthesis method, mechanisms of antimicrobial action, and the comparison of antimicrobial performance between these two kinds of polymers. PMID:25667977

  20. A quaternary temperament model and defense cluster preferences.

    PubMed

    Kelly, Kathryn E; Tobacyk, Jerome J

    2003-10-01

    A quaternary model of temperament constructed from orthogonal axes defined by Extraversion-Introversion and Thinking-Feeling resulted in four groups: Introverted Thinking, Introverted Feeling, Extraverted Thinking, and Extraverted Feeling. Hypothesized relationships between quaternary groups and defense cluster preferences were tested by giving 158 female college students the Myers-Briggs Type Indicator and the Defense Mechanisms Inventory. There was little support for hypothesized relationships between the quaternary model and defense preferences. The only hypothesized significant group difference showed the Extraverted Feeling group recording a greater preference for the Reversal defense cluster than the Introverted Feeling group. PMID:14650666

  1. Biocide comparison: Aldehyde versus mixture of aldehyde and quaternary amine

    SciTech Connect

    Prasad, R. [Champion Technologies, Inc., Houston, TX (United States)

    1994-12-31

    Glutaraldehyde and quaternary ammonium chloride salts are widely used biocides in oil field systems to control microbiologically influenced corrosion (MIC). These biocides and others were evaluated for their efficacy to control sessile and planktonic sulfate reducing bacteria (SRB) and aerobic bacteria. The efficacy of these biocides was then compared. In addition to laboratory evaluation, all the biocides were evaluated against SRB and acid producing bacteria in two different field waters. It was found that the blend containing aldehyde and quaternary amino was, in general, a more effective biocide than either glutaraldehyde or quaternary amine alone.

  2. Continental shelf drift deposit indicates non-steady state Antarctic bottom water production in the Holocene

    Microsoft Academic Search

    Peter T. Harris; Giuliano Brancolini; Leanne Armand; Martina Busetti; Robin J. Beaman; Giovanna Giorgetti; Massimo Presti; Fabio Trincardi

    2001-01-01

    A late Quaternary, current-lain sediment drift deposit over 30m in thickness has been discovered on the continental shelf of East Antarctica in an 850m deep glacial trough off George Vth Land. Radiocarbon dating indicates that a period of rapid deposition on the drift (averaging 290cm\\/kyr) occurred in the mid-Holocene, between about 3000 and 5000yr before present (yrbp). Slower deposition rates

  3. Quaternary coral reef refugia preserved fish diversity.

    PubMed

    Pellissier, Loïc; Leprieur, Fabien; Parravicini, Valeriano; Cowman, Peter F; Kulbicki, Michel; Litsios, Glenn; Olsen, Steffen M; Wisz, Mary S; Bellwood, David R; Mouillot, David

    2014-05-30

    The most prominent pattern in global marine biogeography is the biodiversity peak in the Indo-Australian Archipelago. Yet the processes that underpin this pattern are still actively debated. By reconstructing global marine paleoenvironments over the past 3 million years on the basis of sediment cores, we assessed the extent to which Quaternary climate fluctuations can explain global variation in current reef fish richness. Comparing global historical coral reef habitat availability with the present-day distribution of 6316 reef fish species, we find that distance from stable coral reef habitats during historical periods of habitat loss explains 62% of the variation in fish richness, outweighing present-day environmental factors. Our results highlight the importance of habitat persistence during periods of climate change for preserving marine biodiversity. PMID:24876495

  4. On Quaternary glaciations, observations and theories

    NASA Astrophysics Data System (ADS)

    Paillard, D.

    2015-07-01

    In a recent paper, Paillard (2015) presents a rapid overview of both major theoretical and empirical studies of Pleistocene glaciations. In particular, it is explained how, over the last 150 years, astronomical theories were confronted to observational constraints and why the "100-kyr problem" is still the major unsolved issue of Quaternary ice ages. This paper also discusses the main alternative theory, which involves changes in atmospheric carbon dioxide concentration. It is then argued that a synthesis of both theories would better account for empirical evidences, as well as for our current knowledge of climate physics. Indeed, if there is no doubt that ice ages are "paced" by the astronomy as evidenced in Hays et al. (1976), the cause of terminations, and therefore the dynamics of the 100-kyr cycles, appears to be closely linked to Southern Ocean climate and atmospheric pCO2.

  5. Antifungal activity of gemini quaternary ammonium salts.

    PubMed

    Ob??k, Ewa; Piecuch, Agata; Krasowska, Anna; Luczy?ski, Jacek

    2013-12-14

    A series of gemini quaternary ammonium chlorides and bromides with various alkyl chain and spacer lengths was synthesized. The most active compounds against fungi were chlorides with 10 carbon atoms within the hydrophobic chain. Among these compounds were few with no hemolytic activity at minimal inhibitory concentrations. None of the tested compounds were cytotoxic and mutagenic. Cationic gemini surfactants poorly reduced the adhesion of microorganisms to the polystyrene plate, but inhibited the filamentation of Candida albicans. One of the tested compounds eradicated C. albicans and Rodotorula mucilaginosa biofilm, what could be important in overcoming catheter-associated infections. It was also shown that gemini surfactants enhanced the sensitivity of C. albicans to azoles and polyenes, thus they might be potentially used in combined therapy against fungi. PMID:23827647

  6. Suggested terminology for Quaternary dating methods

    USGS Publications Warehouse

    Colman, Steven M.; Pierce, K.L.; Birkeland, P.W.

    1987-01-01

    Classification of Quaternary dating methods should be based on the level of quantitative information and the degree of confidence contained in the age estimates produced by the dating methods. We recommend the use of the terms numerical-age, calibrated-age, relative-age, and correlated-age to describe these levels. We also classify dating methods by type into sideral, isotopic, radiogenic, chemical and biological, geomorphic, and correlation methods. The use of "absolute" is inappropriate for most dating methods, and should be replaced by "numerical." The use of "date" should be minimized in favor of "age" or "age estimate." We recommend use of the abbreviations ka and Ma for most ages; calender dates can be used where appropriate and yr B.P. can be used for radiocarbon ages. ?? 1987.

  7. [Quaternary ammonium compounds--new occupational hazards].

    PubMed

    Lipi?ska-Ojrzanowska, Agnieszka; Walusiak-Skorupa, Jolanta

    2014-01-01

    Quaternary ammonium compounds (QACs, quats) belong to organic ionic chemical agents which display unique properties of both surfactants and disinfectants. Their wide distribution in the work environment and also in private households brings about new occupational hazards. This paper reviews reports about the health effects of QACs. QACs could play a role of sensitizers and irritants to the skin and mucous membranes. It is suspected that particular QACs can display an immunologic cross-reactivity between each other and with other chemical compounds containing ammonium ion, such as muscle relaxants widely used in anesthesia. T