Sample records for miocene hawthorn group

  1. Hawthorn

    MedlinePLUS

    ... Hawthorn is a spiny, flowering shrub or small tree of the rose family. The species of hawthorn discussed here are native to northern European regions and grow throughout the world. Historically, hawthorn fruit has been used for heart ...

  2. Hawthorne in Salem

    NSDL National Science Digital Library

    During his days as a clerk for the federal government in Salem, Massachusetts, Nathaniel Hawthorne began crafting some of his most notable works. The Hawthorne in Salem site celebrates his life and times in this very unique place. Created by the North Shore Community College in nearby Danvers, the site offers up an interactive timeline of dates from Hawthorne's life. Visitors can browse through six sections, including Life & Times, Literature, and Buildings and Houses. The Maps area is a delight, offering maps of Salem Village, Salem in Hawthorneâ??s time, as well as Salem today. Accompanying articles also provide riveting insight into Salem around the time of Hawthorneâ??s birth in 1804. The siteâ??s introductory video is also worth a look.

  3. 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.

  4. Funalichnus bhubani isp. nov. from Bhuban Formation, Surma Group (Lower -Middle Miocene) of Aizawl, Mizoram, India

    PubMed Central

    Tiwari, Raghavendra Prasad; Rajkonwar, Chinmoy; Patel, Satish Jaychandbhai

    2013-01-01

    A new ichnospecies of the ichnogenus Funalichnus Pokorný is described from the Middle Bhuban Unit, Bhuban Formation, Surma Group (Lower - Middle Miocene) of Aizawl, Mizoram, India. Funalichnus bhubani isp. Nov. Is a large burrow displaying cylindrical segments that are oriented nearly perpendicular to the bedding plane. The new ichnospecies can be identified on the basis of general form, size, unlined passive filling and twisted rod-like structure. The association of Funalichnus bhubani isp. Nov. With Arenicolites, Diplocraterion, Ophiomorpha Psilonichnus Skolithos and Thalassinoides points to its bathymetric restriction. The deep extension of the burrow in clastic sediments provides a favourable condition for preservation in the shoreface environment and occurrence in fine- to medium-grained clastic sediments may be a preservational preference. PMID:24204992

  5. A dolomitized diatomite in an Oligocene–Miocene deep-sea fan succession, Gonfolite Lombarda Group, Northern Italy

    Microsoft Academic Search

    D. Bernoulli; B Gunzenhauser

    2001-01-01

    An unique, 5–10cm thick layer of a dolomitized diatomite, which contains traces of volcanic material, occurs intercalated between terrigenous mudstones, thin-bedded turbidites and pebbly mudstones of the Montana Member (Burdigalian) of the Oligocene–Miocene Gonfolite Lombarda Group (“South-Alpine Molasse”). Dolomite formation took place during early diagenesis under conditions of sulfate reduction as suggested by the strongly negative ?13C values (??13‰ PDB).

  6. 12. Photocopy of photograph (original located in Photograph's Office, Hawthorne ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. Photocopy of photograph (original located in Photograph's Office, Hawthorne Army Ammunition Plant, Hawthorne, Nevada). View of swimming pool, photograph no. 20107-27. - Hawthorne Naval Ammunition Depot, Gymnasium, North Main Avenue, Industrial Area, Hawthorne Army Ammunition Plant, Hawthorne, Mineral County, NV

  7. 11. Photocopy of photograph (original located in Photograph's Office, Hawthorne ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. Photocopy of photograph (original located in Photograph's Office, Hawthorne Army Ammunition Plant, Hawthorne, Nevada). View of gymnasium, photograph no. 20107-28. - Hawthorne Naval Ammunition Depot, Gymnasium, North Main Avenue, Industrial Area, Hawthorne Army Ammunition Plant, Hawthorne, Mineral County, NV

  8. 76 FR 67103 - Proposed Revision of Class D and Class E Airspace; Hawthorne, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-31

    ...Class D and Class E Airspace; Hawthorne, CA AGENCY: Federal Aviation Administration...Hawthorne Municipal Airport, Hawthorne, CA. Additional controlled airspace is needed...Hawthorne Municipal Airport, Hawthorne, CA, creating additional airspace...

  9. The Hawthorne Effect: A Fresh Examination.

    ERIC Educational Resources Information Center

    Diaper, Gordon

    1990-01-01

    Reexamines definitions of and explanations for the Hawthorne Effect in research subjects. Notes that the Hawthorne Effect was tested in a study of the effectiveness of paired classroom reading among students. Challenges the notion that subject's behavior is modified by participation in research. Reviews various research studies that question the…

  10. 77 FR 7525 - Revision of Class D and Class E Airspace; Hawthorne, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-13

    ...Class D and Class E Airspace; Hawthorne, CA AGENCY: Federal Aviation Administration...Hawthorne Municipal Airport, Hawthorne, CA. Additional controlled airspace is needed...amend controlled airspace at Hawthorne, CA (76 FR 67103). Interested parties...

  11. 77 FR 64889 - Amendment of Class D and Class E Airspace; Hawthorne, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-24

    ...Class D and Class E Airspace; Hawthorne, CA AGENCY: Federal Aviation Administration...Hawthorne Municipal Airport, Hawthorne, CA. The FAA is taking this action in response...aircraft operations for the Hawthorne, CA, area. DATES: Effective date, 0901...

  12. Entomosporium Leafspot of Photinia and Indian Hawthorn 

    E-print Network

    Ong, Kevin

    2003-03-12

    This leaflet describes the fungus Entomosporium, which attacks photinia and Indian hawthorn plants. The publication describes the disease cycle and recommends cultural practices to control and treat the disease....

  13. Hypotensive effects of hawthorn for patients with diabetes taking prescription drugs: a randomised controlled trial

    PubMed Central

    Walker, Ann F; Marakis, Georgios; Simpson, Eleanor; Hope, Jessica L; Robinson, Paul A; Hassanein, Mohamed; Simpson, Hugh CR

    2006-01-01

    Background Hawthorn (Crataegus laevigata) leaves, flowers and berries are used by herbal practitioners in the UK to treat hypertension in conjunction with prescribed drugs. Small-scale human studies support this approach. Aim To investigate the effects of hawthorn for hypertension in patients with type 2 diabetes taking prescribed drugs. Design of study Randomised controlled trial. Setting General practices in Reading, UK. Method Patients with type 2 diabetes (n = 79) were randomised to daily 1200 mg hawthorn extract (n = 39) or placebo (n = 40) for 16 weeks. At baseline and outcome a wellbeing questionnaire was completed and blood pressure and fasting blood samples taken. A food frequency questionnaire estimated nutrient intake. Results Hypotensive drugs were used by 71% of the study population with a mean intake of 4.4 hypoglycaemic and/or hypotensive drugs. Fat intake was lower and sugar intake higher than recommendations, and low micronutrient intake was prevalent. There was a significant group difference in mean diastolic blood pressure reductions (P = 0.035): the hawthorn group showed greater reductions (baseline: 85.6 mmHg, 95% confidence interval [CI] = 83.3 to 87.8; outcome: 83.0 mmHg, 95% CI = 80.5 to 85.7) than the placebo group (baseline: 84.5 mmHg, 95% CI = 82 to 87; outcome: 85.0 mmHg, 95% CI = 82.2 to 87.8). There was no group difference in systolic blood pressure reduction from baseline (3.6 and 0.8 mmHg for hawthorn and placebo groups, respectively; P = 0.329). Although mean fat intake met current recommendations, mean sugar intake was higher and there were indications of potential multiple micronutrient deficiencies. No herb–drug interaction was found and minor health complaints were reduced from baseline in both groups. Conclusions This is the first randomised controlled trial to demonstrate a hypotensive effect of hawthorn in patients with diabetes taking medication. PMID:16762125

  14. A "H--ll-Fired Story": Hawthorne's Rhetoric of Rumor.

    ERIC Educational Resources Information Center

    Harshbarger, Scott

    1994-01-01

    Considers Nathaniel Hawthorne's literary technique of providing various, often conflicting, accounts of a narrative scene or event. Analyzes Hawthorne's rhetoric of rumor as featured in "The Scarlet Letter." Shows how Hawthorne tried to translate the dynamics of interpersonal communication into print in this novel. (HB)

  15. Isotopic constraints on the genesis and age of autochthonous glaucony in the Oligo-Miocene Torquay Group, south-eastern Australia

    Microsoft Academic Search

    JONATHAN C. K ELLY; JOHN A. W EBB; R OLAND M AAS

    2001-01-01

    The Oligo-Miocene Torquay Group at Bird Rock in south-eastern Australia comprises a sequence of fine-grained skeletal carbonates and argillaceous and glauconitic sandstones, deposited in a cool-water, mid-shelf environment. The Bird Rock glaucony is autochthonous and consists predominantly of randomly interstratified glauconitic smectite, which constitutes bioclast infills and faecal pellet replacements. The results of Rb-Sr and oxygen isotopic analysis of samples

  16. The Hawthorne effect and energy awareness.

    PubMed

    Schwartz, Daniel; Fischhoff, Baruch; Krishnamurti, Tamar; Sowell, Fallaw

    2013-09-17

    The feeling of being observed or merely participating in an experiment can affect individuals' behavior. Referred to as the Hawthorne effect, this inconsistently observed phenomenon can both provide insight into individuals' behavior and confound the interpretation of experimental manipulations. Here, we pursue both topics in examining how the Hawthorne effect emerges in a large field experiment focused on residential consumers' electricity use. These consumers received five postcards notifying, and then reminding, them of their participation in a study of household electricity use. We found evidence for a Hawthorne (study participation) effect, seen in a reduction of their electricity use--even though they received no information, instruction, or incentives to change. Responses to a follow-up survey suggested that the effect reflected heightened awareness of energy consumption. Consistent with that interpretation, the treatment effect vanished when the intervention ended. PMID:24003110

  17. Capillary electrophoretic analysis of flavonoids in single-styled hawthorn ( Crataegus monogyna Jacq.) ethanolic extracts

    Microsoft Academic Search

    A. Urbonavi?i?t?; V. Jakštas; O. Kornyšova; V. Janulis; A. Maruška

    2006-01-01

    Flavonoids are an important group of natural compounds, which can prevent coronary heart disease and have antioxidant properties. Hawthorn is a well known and widely used medicinal plant due to its cardiotonic activity. Previous studies refer mostly to the HPLC analysis of the flavonoids: vitexin, quercetin, hyperoside, oligomeric procyanidins, which appear to be primarily responsible for the cardiac action of

  18. Black-fruited hawthorns of western North America one or more agamic complexes?

    Microsoft Academic Search

    Timothy A. Dickinson; Eugenia Y. Y. Lo; Nadia Talent; Rhoda M. Love

    2008-01-01

    Black-fruited hawthorns in North America comprise two taxonomic groups within the genus Crataegus, section Brevispinae and section Douglasianae. The first of these has recently been shown to be monospecific, consisting of the blue- berry haw, Crataegus brachyacantha Sarg. & Engelm., of Louisiana and Texas. Crataegus section Douglasianae, however, comprises several taxa in a single clade that is not closely related

  19. Incremental Compositional Zoning in the Widespread Phonolitic Ayagaures Ignimbrite in Miocene Fataga Group on Gran Canaria (Canary Islands)

    NASA Astrophysics Data System (ADS)

    Jutzeler, M.; Schmincke, H.; Sumita, M.

    2006-12-01

    The widespread phonolitic Ayagaures Ignimbrite (AI) (11.8 Ma) is a moderately to highly welded cooling unit of the Miocene Fataga Group (ca 13.3 - ca 9 Ma) on Gran Canaria (GC) (Canary Islands). Most of the up to 20 flow units have been mapped throughout the exposed area of at least 250km2. AI (average thickness 20- 25 m) dips regularly 4-5° in southern to southwestern GC and has reached the sea at many places. Its mapped volume is approximately 4.5 km3. This plus tentatively correlated ODP syn-ignimbrite deposits (Sumita and Schmincke, 1998 and unpubl.) and its probable former widespread distribution over at least western GC suggest a total erupted magma volume of >50km3. Phonolitic AI contains up to 20 vol % of dominantly anorthoclase-sanidine and minor (<1 vol %) biotite, Fe- augite, titanite, haüyne and apatite. The cooling unit is compositionally zoned becoming more mafic upwards. Trace elements and REE show significant magma reservoir zoning in both bulk rock and phenocryst composition, while major elements change little. All phenocryst species were unzoned and their composition within each flow unit extremely homogeneous. The shallow level magma reservoir is interpreted to have been compositionally zoned but thermodynamically equilibrated. Strong mixing preceded the separation of the magma chamber into several small convective layers in which one single growth event of alkali feldspar and biotite occurred. The presence of large haüyne and titanite crystals within the topmost layers of the reservoir (basal flow unit) and a locally preserved highly evolved fallout tephra document a highly fractionated volatile-rich but small-volume cupola. AI represents the most evolved part of a larger partially evacuated magma reservoir. Progressive downward tapping of the reservoir was controlled by incremental caldera collapse. Unzoned phenocrysts, incremental CU zoning and evacuation reversals show that mixing did not occur after separation into layers.

  20. Hawthorn ( Crataegus spp.) fruit: some physical and chemical properties

    Microsoft Academic Search

    Musa Özcan; Haydar Hac?sefero?ullar?; Tamer Marako?lu; Derya Arslan

    2005-01-01

    The hawthorn (Crataegus spp.) fruits were analysed for some physical (dimensions, geometric mean diameter, sphericity, bulk density, fruit density, volume, terminal velocity, hardness and porosity) and chemical (moisture, crude protein, crude oil, crude energy, crude fiber, ash, pH, acidity, water- and alcohol soluble extract) properties. Mineral content of wild hawthorn growing in Turkey were determined by Inductively Coupled Plasma Atomic

  1. Tissue distribution comparison between healthy and fatty liver rats after oral administration of hawthorn leaf extract.

    PubMed

    Yin, Jingjing; Qu, Jianguo; Zhang, Wenjie; Lu, Dongrui; Gao, Yucong; Ying, Xixiang; Kang, Tingguo

    2014-05-01

    Hawthorn leaves, a well-known traditional Chinese medicine, have been widely used for treating cardiovascular and fatty liver diseases. The present study aimed to investigate the therapeutic basis treating fatty liver disease by comparing the tissue distribution of six compounds of hawthorn leaf extract (HLE) in fatty liver rats and healthy rats after oral administration at first day, half month and one month, separately. Therefore, a sensitive and specific HPLC method with internal standard was developed and validated to determine chlorogenic acid, vitexin-4''-O-glucoside, vitexin-2''-O-rhamnoside, vitexin, rutin and hyperoside in the tissues including heart, liver, spleen, kidney, stomach and intestine. The results indicated that the six compounds in HLE presented some bioactivity in treating rat fatty liver as the concentrations of the six compounds varied significantly in inter- and intragroup comparisons (healthy and/or fatty liver group). PMID:24254959

  2. Sedimentology of the Whiteclay Gravel Beds (Ogallala Group) in northwestern Nebraska, USA: Structurally controlled drainage promoted by Early Miocene uplift of the Black Hills Dome

    NASA Astrophysics Data System (ADS)

    Fielding, Christopher R.; LaGarry, Hannan E.; LaGarry, Leigh Anne; Bailey, Bruce E.; Swinehart, James B.

    2007-11-01

    The newly recognized Whiteclay Gravel Beds (WGB) of the Miocene Ogallala Group crop out as a narrow, discontinuous ribbon of sands and gravels in Dawes and Sheridan Counties, northwestern Nebraska, USA. The WGB are exposed in a series of municipal gravel quarries and natural exposures that define a linear trench in underlying strata at least 20 m deep and up to 300 m wide, with short, southeast-trending reaches separating generally longer east-trending sections. This gravel-filled trench can be recognized from the Nebraska-South Dakota border near Whiteclay, Nebraska southeastward to east of Gordon, Nebraska, a distance of ˜ 30 km. The outcrop belt of the WGB is coincident in location and trend with the Whiteclay Fault Zone. Where exposed in quarries, the walls of the trench are steep-sided, vertical, or locally overhanging. Polished surfaces, slickensides, and parallel joint sets are common in the walls of the trench near Whiteclay, but uncommon in those to the east. The narrow belt defined by this trench is filled by stratified gravel (< 2.0 m, typically < 0.3 m) of sedimentary lithologies derived from various Cenozoic units (but principally Anderson Ranch Formation), and sand. Relatively small amounts of unrounded granitic, volcanic, and quartz gravel are preserved in places. Cross-bedding and clast imbrication indicate palaeoflow towards the east. The WGB are interpreted to have formed in response to tectonic upheaval associated with uplift of the Black Hills of South Dakota in Early Miocene times. Fault rupture topography facilitated formation of a steep-sided canyon, or valley, up to 20 m deep, being virtually straight with sharp bends at intervals of several km. An alluvial channel belt developed in the floor of the valley, filling the available accommodation space with coarse sand and gravel via aggradational stacking of the deposits of successive channels and channel belts. Channel belts were probably braided, with individual channels up to 4 m deep and a few tens of metres wide. The multi-storey character of the deposit indicates multiple episodes of cutting and filling. The coarse grain-size of the fill suggests energetic discharge with frequent bankfull flows, even though the system had a relatively low gradient (0.004). An abundance of reworked fossil debris is derived from several stratigraphic units, clasts of which have been identified in the fill. The presence of a contemporary merychippine horse and a primitive species of the oreodont Brachycrus constrain formation of the WGB to a short interval within the Early Miocene (c. 17.5 Ma). The mammal fauna suggests that this stream was a valuable source of water, while fragments of aquatic organisms such as turtles and fish indicate perennial discharge. The WGB provides a crucial window into a pluvial period in the Miocene that is largely unpreserved elsewhere in the basin, facilitated in part by fault rupture topography.

  3. Interview with Geoffrey Hawthorn on Malthus and population

    E-print Network

    Hawthorn, Geoffrey

    2009-06-30

    An interview with the sociologist Geoffrey Hawthorn in relation to Malthus and population, made in 1985 as part of the materials for the film 'The Mountebank Parson' made by Sofka Zinovieff, Rachel Riley and John Bell in that year...

  4. Interview with Geoffrey Hawthorn on Malthus and population

    E-print Network

    Hawthorn, Geoffrey

    1985-01-01

    An interview with Geoffrey Hawthorn in relation to Malthus and population, made in 1985 as part of the materials for the film 'The Mountebank Parson' by Sofka Zinovieff, Rachel Riley and John Bell in that year...

  5. Effect of storage temperature on phenolics stability in hawthorn ( Crataegus pinnatifida var. major) fruits and a hawthorn drink

    Microsoft Academic Search

    Qi Chang; Zhong Zuo; Moses S. S. Chow; Walter K. K. Ho

    2006-01-01

    The stability of five major phenolics, namely (?)-epicatechin (EC), procyanidin B2 (PC-B2), chlorogenic acid (ChA), hyperoside (HP) and isoquercitrin (IQ), in hawthorn fruits and a canned hawthorn drink were evaluated during 6 months of storage in the dark at three different temperatures (4, 23 and 40°C). HPLC with a diode-array detector was used to determine the contents of the individual

  6. The Effectiveness of Crataegus orientalis M Bieber. (Hawthorn) Extract Administration in Preventing Alveolar Bone Loss in Rats with Experimental Periodontitis.

    PubMed

    Hatipo?lu, Mükerrem; Sa?lam, Mehmet; Köseo?lu, Serhat; Köksal, Ekrem; Kele?, Ali; Esen, Hac? Hasan

    2015-01-01

    The purpose of this animal study was to evaluate the effects of hawthorn (Crataeus orientalis M Bieber.) extract on serum oxidative status and alveolar bone loss in experimental periodontitis. Twenty-seven Wistar rats were assigned to one of the following groups: non- ligated+placebo (saline) (NL, n = 9), ligature only+placebo (saline) (LO, n = 9), and ligature and treated with hawthorn extract in saline (H, n = 9) (100 mg/kg orogastrically, once a day for 11 days). Periodontitis was induced by submerging a 4/0 silk ligature in the sulcus of the mandibular right first molars of rats, and the animals were sacrificed after 11 days. Micro-CT examinations were performed for linear and volumetric parameter assessment of alveolar bone. Periodontal tissues were histopathologically examined to assess the differences among the study groups. Levels of serum total antioxidant status (TAS)/total oxidant status (TOS), and oxidative stress index (OSI) were also analyzed. Alveolar bone loss was significantly reduced by hawthorn administration compared to LO group (p<0.05). The number of inflammatory cells and osteoclasts in the LO group was significantly higher than that of the NL and H groups (p< 0.05). The number of osteoblasts in the LO and H groups was significantly higher than that of the NL group (p<0.05). TOS and OSI levels were significantly reduced in H group compared to LO group (P <0.05) and TAS levels were similar in H and NL group (p< 0.05). Hawthorn extract showed inhibitory effect on periodontal inflammation and alveolar bone loss by regulating TAS, TOS and OSI levels in periodontal disease in rats when administered systemically. PMID:26030160

  7. The Effectiveness of Crataegus orientalis M Bieber. (Hawthorn) Extract Administration in Preventing Alveolar Bone Loss in Rats with Experimental Periodontitis

    PubMed Central

    Hatipo?lu, Mükerrem; Sa?lam, Mehmet; Köseo?lu, Serhat; Köksal, Ekrem; Kele?, Ali; Esen, Hac? Hasan

    2015-01-01

    The purpose of this animal study was to evaluate the effects of hawthorn (Crataeus orientalis M Bieber.) extract on serum oxidative status and alveolar bone loss in experimental periodontitis. Twenty-seven Wistar rats were assigned to one of the following groups: non- ligated+placebo (saline) (NL, n = 9), ligature only+placebo (saline) (LO, n = 9), and ligature and treated with hawthorn extract in saline (H, n = 9) (100 mg/kg orogastrically, once a day for 11 days). Periodontitis was induced by submerging a 4/0 silk ligature in the sulcus of the mandibular right first molars of rats, and the animals were sacrificed after 11 days. Micro-CT examinations were performed for linear and volumetric parameter assessment of alveolar bone. Periodontal tissues were histopathologically examined to assess the differences among the study groups. Levels of serum total antioxidant status (TAS)/total oxidant status (TOS), and oxidative stress index (OSI) were also analyzed. Alveolar bone loss was significantly reduced by hawthorn administration compared to LO group (p<0.05). The number of inflammatory cells and osteoclasts in the LO group was significantly higher than that of the NL and H groups (p< 0.05). The number of osteoblasts in the LO and H groups was significantly higher than that of the NL group (p<0.05). TOS and OSI levels were significantly reduced in H group compared to LO group (P <0.05) and TAS levels were similar in H and NL group (p< 0.05). Hawthorn extract showed inhibitory effect on periodontal inflammation and alveolar bone loss by regulating TAS, TOS and OSI levels in periodontal disease in rats when administered systemically. PMID:26030160

  8. American Studies in Review: The Recuperative Trend in Hawthorne Studies: New or Improved?

    Microsoft Academic Search

    Luke Bresky

    2011-01-01

    : This essay reviews two collections of essays (Hawthorne and the Real: Bicentennial Essays, edited by Millicent Bell, and The Cambridge Companion to Nathaniel Hawthorne, edited by Richard Millington) and Brenda Wineapple’s Hawthorne: A Life. These books raise questions about the currency of late-twentieth-century reassessments of Hawthorne’s significance: is “our” Hawthorne still to be read as an anxious conservative, tainted

  9. American Studies in Review: The Recuperative Trend in Hawthorne Studies: New or Improved?

    Microsoft Academic Search

    Luke Bresky

    2011-01-01

    This essay reviews two collections of essays (Hawthorne and the Real: Bicentennial Essays, edited by Millicent Bell, and The Cambridge Companion to Nathaniel Hawthorne, edited by Richard Millington) and Brenda Wineapple’s Hawthorne: A Life. These books raise questions about the currency of late-twentieth-century reassessments of Hawthorne’s significance: is “our” Hawthorne still to be read as an anxious conservative, tainted by

  10. First middle Miocene sivaladapid primate from Thailand.

    PubMed

    Chaimanee, Yaowalak; Yamee, Chotima; Tian, Pannipa; Chavasseau, Olivier; Jaeger, Jean-Jacques

    2008-03-01

    Sivaladapids are a group of Asian adapiform primates that were previously documented from deposits dating to the middle Eocene through the late Miocene in Pakistan, India, Myanmar, Thailand, and China. The group is notable for the persistence of three genera, Sivaladapis, Indraloris and Sinoadapis, into the late Miocene. In Thailand, sivaladapids were previously documented only from late Eocene deposits of the Krabi mine. Here, we describe the first Southeast Asian Miocene sivaladapid, Siamoadapis maemohensis gen. et sp. nov. from a 13.3 to 13.1 Ma lignite layer from the Mae Moh coal mine, Thailand. It differs from other Miocene sivaladapids by its distinctly smaller size and in features of the dentition. This discovery enhances the paleoecological diversity of the middle Miocene primate fauna of Thailand, which now includes sivaladapids, a loris, tarsiids, and hominoids. In this respect, the fossil primate community from the middle Miocene of Thailand is similar in its composition to roughly contemporaneous assemblages from southern China, India, and Pakistan. However, the Thai fossils represent a distinct genus, suggesting a different biogeographic province with distinctive paleoenvironments. PMID:18022213

  11. Interaction Study between Digoxin and a Preparation of Hawthorn [Crataegus oxyacantha

    Microsoft Academic Search

    Roberta Tankanow; Helen R. Tamer; Daniel S. Streetman; Scott G. Smith; Janice L. Welton; Thomas Annesley; Keith D. Aaronson; Barry E. Bleske

    2003-01-01

    Hawthorn, an herbal supplement, is currently being evaluated for the treatment of heart failure. The flavonoid components of hawthorn may be responsible for hawthorn's beneficial effects in the treatment of heart failure. However, these components may also affect P-glycoprotein function and cause interactions with drugs that are P-glycoprotein substrates, such as digoxin, which is also used to treat heart failure.

  12. Some Fruit Traits of Hawthorn (Crataegus spp.) Genetic Resources from Malatya, Turkey

    Microsoft Academic Search

    M. Fikret Balta; F. Çelik; N. Turkoglu; K. Ozrenk; F. Ozgokçe

    Hawthorns (Crataegus spp.) are native to Turkey. It is possible to see wild hawthorn bushes or trees in every regions of Turkey. This study deals with evaluating fruit characteristics of 42 genotypes belonging to five different hawthorn species collected from Malatya (eastern Turkey). The mean values of fruit height, fruit diameter, fruit weight, seed height and seed diameter differed statistically

  13. Identification of Host Fruit Volatiles from Hawthorn ( Crataegus spp.) Attractive to Hawthorn-Origin Rhagoletis pomonella Flies

    Microsoft Academic Search

    Satoshi Nojima; Bruce Morris; Aijun Zhang; Wendell Roelofs

    2003-01-01

    Solid-phase microextraction (SPME) and gas chromatography coupled with electroantennographic detection (GC-EAD) were used to identify volatile compounds from hawthorn fruit (Crataegus spp.) acting as behavioral attractants for hawthorn-infesting Rhagoletis pomonella flies. Consistent EAD activity was obtained for six chemicals: ethyl acetate (94.3%), 3-methylbutan- 1-ol (4.0%), isoamyl acetate (1.5%), 4,8-dimethyl-1,3(E),7-nonatriene (0.07%), butyl hexanoate (0.01%), and dihydro-ß-ionone (0.10%). In a flight-tunnel bioassay,

  14. Yields of hawthorn Crataegus monogyna berries under different hedgerow management

    Microsoft Academic Search

    T. H Sparks; T Martin

    1999-01-01

    Yields of hawthorn berries under different hedgerow management treatments were examined in experimental hedgerows at Monks Wood, Cambridgeshire, UK. Statistically significant differences existed between the management treatments with yields per unit area of hedgerows unmanaged for more than a decade out-yielding managed hedgerows by an order of magnitude. These differences were further inflated if yields were considered per unit length

  15. Mozart, Hawthorne, and Mario Savio: Aesthetic Power and Political Complicity.

    ERIC Educational Resources Information Center

    Herbert, T. Walter

    1995-01-01

    Discusses the false dichotomy pitting aesthetic power against political complicity in literary criticism. Considers the sexual politics of the household of Nathaniel Hawthorne in light of this opposition. Suggests how literary works keep warring voices and inner conflicts alive and at odds. (HB)

  16. Nathaniel Hawthorne and Herman Melville: A Research Guide.

    ERIC Educational Resources Information Center

    Van Noate, Judith, Comp.

    This handout is a guide to library resources in the J. Murrey Atkins Library at the University of North Carolina-Charlotte for the study of the 19th-century American authors Nathaniel Hawthorne and Herman Melville. The guide details resources in Atkins library for biographical and critical material on the two authors. The guide is in four…

  17. Nathaniel Hawthorne's Garden of Eden Story: "Rappaccini's Daughter."

    ERIC Educational Resources Information Center

    Meixner, Linda L.

    1990-01-01

    Presents a four-day lesson plan for secondary U.S. literature or Bible-and-literature classes, using the Garden of Eden story and Nathaniel Hawthorne's "Rappaccini's Daughter." Identifies objectives, materials, procedure, and evaluation measures. Develops students' ability to discover analogies and irony in literary texts. Lists teacher resources,…

  18. UBC Museum of Anthropology Audrey & Harry Hawthorn Library & Archives

    E-print Network

    Strynadka, Natalie

    UBC Museum of Anthropology Audrey & Harry Hawthorn Library & Archives Application Form for Use of Archival Materials Please direct all requests for reproduction and use of archival materials to Krisztina, please specify MOA Archive number(s) and fonds/collection or give detailed description: 2. Provide

  19. Is the Hawthorne Effect in Educational Experiments a Chimera?

    ERIC Educational Resources Information Center

    Bauernfeind, Robert H.; Olson, Carl J.

    1973-01-01

    Reports on an experimental study designed to investigate the relationship between two factors commonly regarded as components of the Hawthorne Effect on pupil performance and on intellectual task. These factors are (1) direct cue, or awareness of experimentation, as represented by an announcement that pupils were the subjects of an experiment; and…

  20. Parasitism of the apple maggot, Rhagoletis pomonella , infesting hawthorns in Washington

    Microsoft Academic Search

    L. J. Gut; J. F. Brunner

    1994-01-01

    Five species of larval parasitoids were reared fromRhagoletis pomonella (Walsh) infested fruit of hawthorn,Crataegus, collected from several locations in southwest Washington over a four year period. A braconid,Biosteres melleus (Gahan), parasitized larvae infesting fruits of a native hawthorn species,Crataegus douglasii Lindl. Another braconid,Opius downesi Gahan, emerged exclusively fromR. pomonella pupae reared from fruits of an introduced species of hawthorn,Crataegus monogyna

  1. Metal characterization of white hawthorn organs and infusions.

    PubMed

    Juranovi? Cindri?, Iva; Zeiner, Michaela; Konanov, Darija Mihajlov; Stingeder, Gerhard

    2015-02-18

    Hawthorn is one of the most commonly used European and North American phytopharmaceuticals. Because there is no information on metals in seeds, and only rare data for leaves and flowers, the aim of the present study was elemental analysis of the white hawthorn (Crataegus monogyna) by inductively coupled plasma emission spectrometry (ICP-AES) or inductively coupled plasma mass spectrometry (ICP-MS) after digestion in a microwave-assisted system. The limits of detection are below 2 ?g/g for ICP-AES and 0.5 ?g/g for ICP-MS. Hawthorn leaves and flowers contain essential elements at concentrations (mean values, RSD 2-8%) in mg/g of Ca, 1-4; K, 4-5; Mg, 1-2; and Na, <0.2); and at ?g/g levels of Ba, 1-10; Co, <0.16; Cr, <1.4; Cu, 0.6-7; Fe, 1-37; Li, <0.5; Mn, 1-13; Mo, <0.17; Ni, <0.6; Sr, 0.2-2; and Zn, 1-31. Toxic elements were found in low quantities: As (<0.04), Cd (0.04-0.1), and Pb (0.1-2). Up to 10% of the metals is extracted into the infusions. The analyzed plant parts and infusions contain essential elements justifying its use as a medicinal plant, whereas the low quantities of harmful elements will not pose any risk to humans when consumed. PMID:25630398

  2. Metsulfuron spray drift reduces fruit yield of hawthorn ( Crataegus monogyna L.)

    Microsoft Academic Search

    Christian Kjær; Morten Strandberg; Mogens Erlandsen

    2006-01-01

    This study was carried out to investigate whether spray drift of metsulfuron has a potential to negatively affect hawthorn (Crataegus monogyna) hedgerows near agricultural fields. For this purpose four doses of metsulfuron ranging from 5% to 40% of the field dose (4 g metsulfuron per hectare) were sprayed on trees in seven different hawthorn hedgerows. The actual deposition on the

  3. Hawthorn Fruit Is Hypolipidemic in Rabbits Fed a High Cholesterol Diet1

    Microsoft Academic Search

    Zesheng Zhang; Walter K. K. Ho; Yu Huang; Anthony E. James; Lik Wang Lam; Zhen-Yu Chen

    The present study examined the hypolipidemic activity of hawthorn fruit. New Zealand white rabbits were fed one of three diets, a reference diet with no cholesterol added (NC), a high cholesterol diet (1 g\\/100 g, HC) and a HC diet supplemented with 2 g\\/100 g hawthorn fruit powder (HC-H). After 12 wk, serum total cholesterol (TC) and triacylglycerols (TG) were

  4. THE HAWTHORNE EXPERIMENTS AND THE INTRODUCTION OF JEAN PIAGET IN AMERICAN INDUSTRIAL PSYCHOLOGY, 1929–1932

    Microsoft Academic Search

    Yeh Hsueh

    2002-01-01

    The Hawthorne interview program between 1929 and 1932 was one of the most significant industrial studies in the United States. The Hawthorne researchers applied Jean Piaget’s clinical method in their extensive interviews with tens of thousands of workers. Chiefly responsible for the program’s methodology was Elton Mayo, an Australian who saw interviewing as a means to promote social cooperation. Previous

  5. The "Hawthorne effect" is a myth, but what keeps the story going?

    PubMed

    Kompier, Michiel A J

    2006-10-01

    The Hawthorne studies became famous because of the discovery of the "Hawthorne effect": "a marked increase in production related only to special social position and social treatment". They mark the beginning of the Human Relations School. This article demonstrates that the Hawthorne research does not pass a methodological quality test. Even if methodological shortcomings were waived, there is no proof of a Hawthorne effect in the original data. The following five myths are debunked: (i) scientific worth, (ii) continuous improvement, (iii) social factors prevailing over physical factors and pay, (iv) wholehearted cooperation, and (v) the neurotic worker. The following five factors are held responsible for the creation and survival of the Hawthorne myth: (i) a story too good to be untrue, (ii) bias and selective accounts by original researchers and "laziness" among later scientists, (iii) social factors do matter, and (iv) a story that fits the cognitive world and interests of psychologists, and (v) management. PMID:17091208

  6. Miocene Coralline algae

    SciTech Connect

    Bosence, D.W.J.

    1988-01-01

    The coralline algae (Order Corallinales) were sedimentologically and ecologically important during the Miocene, a period when they were particularly abundant. The many poorly described and illustrated species and the lack of quantitative data in coralline thalli make specific determinations particularly difficult, but some species are well known and widespread in the Tethyan area. The sedimentologic importance of the Miocene coralline algae is reflected in the abundance of in-situ coralline buildups, rhodoliths, and coralline debris facies at Malta and Spain; similar sequences are known throughout the Tethyan Miocene. In-situ buildups vary from leafy crustose biostromes to walled reefs with dense coralline crusts and branches. Growth forms are apparently related to hydraulic energy. Rhodoliths vary from leafy, crustose, and open-branched forms in muddy sediments to dense, crustose, and radial-branching forms in coarse grainstones. Rhodolith form and internal structure correlate closely with hydraulic energy. Coralline genera are conservative and, as such, are useful in paleoenvironmental analysis. Of particular interest are the restricted depth ranges of recent coralline genera. More research is needed on the sedimentology, paleoecology, and systematics of the Cenozoic corallines, as they have particular value in paleoenvironmental analysis.

  7. Review of Miocene larger foraminifera

    SciTech Connect

    Glenn, E.C.

    1988-01-01

    Miocene larger foraminifera were generally restricted to shallow (<100m), warm, clear, normal marine environments and were primarily dependent on brief drifting of juveniles and rafting on vegetation for dispersal. These factors are reflected in both regional and local occurrences. Regional occurrences of Miocene larger foraminifera vary with bio-province and time. Three main foraminiferal provinces (Central American, Mediterranean, and Indo-West Pacific) developed through a combination of tectonics, eustasy, climate, and faunal evolution and migration. Important effects of Miocene tectonics included widening of the Atlantic, early Miocene occlusion of the western neo-Tethys, and northern movement of the Australian plate into the tropics. Changes in climate primarily expanded or constricted latitudinal provincial boundaries. Eustatic sea level variations caused by the destruction of the late Miocene Mediterranean fauna. Globally, Miocene faunas underwent a progressive loss of taxa. This is particularly noticeable in post-early Miocene faunas of the Mediterranean and Central American provinces. Although post-early Miocene taxa evolved in all three areas, faunal migration was prevented by environmental barriers. For a given time and province, the occurrence of larger foraminifera in well-preserved Miocene reef facies is related to paleoenvironmental factors of water depth, turbidity, water energy, and substrate and to post-mortem processes of transport and selective test destruction. Environmentally related changes in test morphology, together with the relative abundances of planktonic species and small benthic taxa, allow an estimation of the magnitude of the various environmental factors, even without detailed foraminiferal taxonomy.

  8. Antarctic Miocene Climate

    NASA Astrophysics Data System (ADS)

    Ashworth, A. C.; Lewis, A. R.

    2013-12-01

    Fossils from Antarctic Miocene terrestrial deposits, coupled with stratigraphic, geochemical and paleontological data from marine boreholes, provide new insights into the climatic history of the continent. During the Miocene, ice caps coalesced to form ice sheets and vegetated surfaces gave way to barren expanses. The cryospheric changes especially have global climatic implications. The fossil data consists of diatoms, pollen and spores, and macroscopic remains of plants, ostracods, insects, molluscs and a fish. Plant fossils include wood and leaves of Nothofagus (southern beech), seeds of several vascular plants, including Ranunculus (buttercup), Hippuris (mare's-tail) and Myriophyllum (watermilfoil), megaspores of Isoetes (quillwort), and moss species. The insect chitin consists of larval head capsules of Chironomidae (midges) and exoskeletal parts of Coleoptera (beetles). The molluscs include freshwater gastropods and bivalves. The majority of these taxa are likely descendants of taxa that had survived on the continent from the Paleogene or earlier. Even though early Miocene glaciations may have been large, the climate was never cold enough to cause the extinction of the biota, which probably survived in coastal refugia. Early Miocene (c. 20 Ma) macrofossils from the McMurdo Dry Valleys (77°S) support palynological interpretations from the Cape Roberts and ANDRILL marine records that the upland vegetation was a shrub tundra. Mean summer temperature (MST) in the uplands was c. 6°C and possibly higher at the coast. The climate was wet, supporting mires and lakes. By the mid-Miocene, even though the climate continued to be wet. MST was c. 4°C which was too cold to support Nothofagus and most vascular plant species. Stratigraphic evidence indicates that the time between the Early and Mid-Miocene was a time of repeated ice advances and retreats of small glaciers originating from ice caps. At c. 14 Ma there appears to have been a modal shift in climate to significantly colder and drier conditions that resulted in the extinction of the upland biota and a shift in glacial regimes from wet to cold-based. Paleontological and geochemical evidence from the deep marine record supports a major climatic event at this time. Based on pollen from the SHALDRIL cores a tundra biota survived until c. 12.8 Ma on the islands of the Antarctic Peninsula (65°S). Recently, sparse angiosperm pollen of chenopods or similar taxa, has been reported from deposits in the Prince Charles mountains (70°S) with a biostratigraphic age of Mid- to Late Miocene (12-9 Ma) making it possible that remnants of a tundra vegetation continued to exist on the edges of the continent after it had become extinct on the islands of the Antarctic Peninsula. Evidence for Pliocene warmth in the Ross Sea from thick diatomite sequence in ANDRILL cores is so far unsupported by terrestrial paleontological evidence. Pliocene wood-like structures reported from a DVDP core are interpreted as the remains of in situ shrubs but the evidence is unconvincing. Pliocene warmth in the Ross sea region, unaccompanied by an unambiguous terrestrial response can be explained in one of two ways: 1. Pliocene MSTs remained below the 3-4°C threshold needed to support shrub or herb tundra, or 2. Pliocene MSTs were warm enough but terrestrial taxa were unavailable because of extinction. Research supported by NSF 0739693,0947821.

  9. [Study on self-microemulsifying membrane controlled-release drop pill of hawthorn leaves flavonoids].

    PubMed

    Wang, Jin-Xuan; Huang, Hong-Zhang; Li, Ning; Gao, Chong-Kai

    2014-03-01

    To prepare the hawthorn leaves flavonoids self-microemulsifying membrane controlled-release coated drop pill, and to study its release rate in vitro and pharmacokinetics study in vivo. In order to improve the dissolution of hawthorn leaves flavonoids, self-microemulsifying technology was used to prepare the hawthorn leaves flavonoids self-microemulsion. Hawthorn leaves flavonoids self-microemulsifying drop pill was prepared with the PEG 6000. Studies were made on the in vitro release of flavonoids from hawthorn leaves self-micro-emulsifying membrane-moderated coated drop pills and the in vivo pharmacokinetic in rats. The prescription of flavonoids from hawthorn leaves self-micro-emulsifying drop pills was 0.25 g of flavonoids from hawthorn leaves, 0.25 g of iodophenyl maleimide, 0.375 g of polyethylene glycol 400, 0.375 g of cremophor RH 40 and 2 g of polyethylene glycol 6000. The optimized prescription was 4 g of ethyl cellulose 20, 0.64 g of polyethylene glycol 400, 1.8 g of diethyl phthalate, and the weight of coating materials increased by 3.5%. Flavonoids from hawthorn leaves self-micro-emulsifying membrane-moderated coated drop pills complied with the design of sustained-release in 12 h in terms of in vitro release and in vivo pharmacokinetic parameters in rats, and its bioavailability was 2.47 times of quick-release drop pills. Slightly soluble flavonoids from hawthorn leaves could be made into sustained-release preparations by the self-micro-emulsifying and coating technology. PMID:25204172

  10. The Hawthorne experiments and the introduction of Jean Piaget in American industrial psychology, 1929-1932.

    PubMed

    Hsueh, Yeh

    2002-05-01

    The Hawthorne interview program between 1929 and 1932 was one of the most significant industrial studies in the United States. The Hawthorne researchers applied Jean Piaget's clinical method in their extensive interviews with tens of thousands of workers. Chiefly responsible for the program's methodology was Elton Mayo, an Australian who saw interviewing as a means to promote social cooperation. Previous discussions of the Hawthorne experiments have ignored the influence of Piaget in the social sciences. This article provides an account of Mayo's and the Hawthorne researchers' efforts to fuse Piaget's innovation with burgeoning American industrial psychology. The endeavor was not an isolated event but rather drew on the theories and practice of Janet-Piaget psychology, on the support of the Laura Spelman Rockefeller Memorial Foundation, and on the discourse among social scientists about Piaget's work. PMID:12096759

  11. Miocene Antarctic Terrestrial Realm

    NASA Astrophysics Data System (ADS)

    Ashworth, A. C.; Lewis, A.; Marchant, D. R.

    2009-12-01

    The discovery of several locations in the Transantarctic Mountains that contain macrofossils and pollen is transforming our understanding of late Cenozoic Antarctica. The most southerly location is on the Beardmore Glacier (85.1°S) about 500 km from the South Pole. The environment was an active glacial margin in which plants, insects and freshwater mollusks inhabited the sand and gravel bars and small lakes on an outwash plain. In addition to leaves and wood of dwarf Nothofagus (Southern Beech) shrubs, achenes of Ranunculus (Buttercup), in situ cushion growth forms of mosses and a vascular plant, the assemblages contains various exoskeletal parts of carabid and curculionid beetles and a cyclorrhaphan fly, the shells of freshwater bivalve and gastropod species and a fish tooth. Initially the deposits were assigned a Pliocene age (3.5 Ma) but a mid- to early Miocene age is more probable (c. 14 - 25 Ma) based on correlation of fossil pollen from the deposits with 39Ar/40Ar dated pollen assemblages from the McMurdo Dry Valleys locations. The oldest location within the Dry Valleys also involved an active ice margin but was part of a valley system that was completely deglaciated for intervals long enough for thick paleosols to develop. The Friis Hills fossil deposits of the Taylor Valley region (77.8°S) are at least 19.76 Ma based on the 39Ar/40Ar age of a volcanic ash bed. The valley floor during the non-glacial phases had poorly-drained soils and the extensive development of mossy mires. Wood and leaves of Nothofagus are abundant in lacustrine deposits. The silts of shallow fluvial channels contain abundant megaspores and spiky leaves of the aquatic lycopod Isoetes (Quillwort). Fossils of beetles are also present in these deposits. During the glacial phases, proglacial lakes were surrounded by dwarfed, deciduous Nothofagus shrubs. The youngest fossils recovered from the Dry Valleys are from the Olympus Range (77.5°S) with an age of 14.07 Ma. The environment was an alpine lake that formed behind a recessional moraine. The fossils are mostly those of freshwater organisms including numerous species of diatoms and an ostracod species in which the soft anatomy is preserved. The base of the lake is marked by a moss bed with exceptionally well-preserved stems and leaves of the extant species Drepanocladus longifolius. Pollen evidence from the Cape Roberts borehole in the Ross Sea basin suggests that tundra existed from the Oligocene to the Early Miocene. Fossil evidence from the Dry Valleys locations indicates that organisms that could not inhabit Antarctica today persisted until c. 14 Ma. At 14 Ma there was a shift in glacial regimes from wet- to cold-based, marking a profound and abrupt climatic shift. We hypothesize that this climate change from warmer and wetter to colder and drier conditions caused the extinction of the tundra biota. It seems probable that at least some of the mid-Miocene fossils are of organisms whose descendants evolved in Antarctica during the Paleogene or earlier. An important consequence of this hypothesis is that the Cenozoic climate of Antarctica was warm enough until the mid-Miocene to support vascular plants and insects. This research was funded by NSF OPP 0739693.

  12. Late Miocene Recent exhumation of the central Himalaya and recycling in the foreland basin assessed by apatite fission-track thermochronology of

    E-print Network

    Boyer, Edmond

    Late Miocene ­ Recent exhumation of the central Himalaya and recycling in the foreland basin Miocene to Pliocene stratigraphic sections of the Siwalik Group in western and central Nepal, as well), others have suggested that fluxes have been decreasing since reaching a peak in middle-late Miocene times

  13. Miocene-Oligocene sequence stratigraphy of the Malay Basin

    SciTech Connect

    Lovell, R.; Elias, M.R. (Esso Production Malaysia Inc., Kuala Lumpur (Malaysia)); Hill, R.E.; Feeley, M.H. (Exxon Production Research Co., Houston, TX (United States))

    1994-07-01

    The Malay Basin has experienced extension of the Eocene ( ) through Oligocene, sag in the early Miocene, and compression in the middle Miocene through Pliocene-Pleistocene. The interaction of structurally induced and glacial-eustatic accommodation changes has resulted in complex, interrelated play elements, including multiple reservoirs, diverse nonmarine sources, discontinuous migration pathways, and thin seals. Extensional subbasins were filled with braided streams, associated coastal plain, lacustrine deltas, and thick lake shales (groups M-K). This initial rift fill comprises an overall second order progradational cycle punctuated by 3rd-order cycles. These 3rd-order cycles are capped by thick, source-rich, lacustrine shale packages. The lower Miocene section (groups I and J) consists of progradational to aggradational fluvial to tidally-dominated estuarine sands. Hydrocarbons are generated from interbedded coals and other coal-related lithologies.

  14. Population genetic structure of diploid sexual and polyploid apomictic hawthorns (Crataegus; Rosaceae) in the Pacific Northwest.

    PubMed

    Lo, Eugenia Y Y; Stefanovi?, Sasa; Dickinson, Timothy A

    2009-03-01

    Polyploidy and gametophytic apomixis are two important and associated processes in plants. Many hawthorn species are polyploids and can reproduce both sexually and apomictically. However, the population genetic structure of these species is poorly understood. Crataegus douglasii is represented exclusively by self-compatible tetraploid pseudogamous apomicts across North America, whereas Crataegus suksdorfii found in the Pacific Northwest is known to include self-incompatible diploid sexuals as well as polyploid apomicts. We compare population structure and genetic variability in these two closely related taxa using microsatellite and chloroplast sequence markers. Using 13 microsatellite loci located on four linkage groups, 251 alleles were detected in 239 individuals sampled from 15 localities. Within-population multilocus genotypic variation and molecular diversity are greatest in diploid sexuals and lowest in triploid apomicts. Apart from the isolation of eastern North American populations of C. douglasii, there is little evidence of isolation by distance in this taxon. Genetic diversity in western populations of C. douglasii suggests that gene flow is frequent, and that colonization and establishment are often successful. In contrast, local populations of C. suksdorfii are more markedly differentiated. Gene flow appears to be limited primarily by distance in diploids and by apomixis and self-compatibility in polyploids. We infer that apomixis and reproductive barriers between cytotypes are factors that reduce the frequency of gene flow among populations, and may ultimately lead to allopatric speciation in C. suksdorfii. Our findings shed light on evolution in woody plants that show heterogeneous ploidy levels and reproductive systems. PMID:19243504

  15. Identification of host fruit volatiles from domestic apple (Malus domestica), native black hawthorn (Crataegus douglasii) and introduced ornamental hawthorn (C. monogyna) attractive to R. pomonella flies from the western U.S.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The apple maggot fly, Rhagoletis pomonella, infests apple (Malus domestica) and hawthorn species (most notably the downy hawthorn, Crataegus mollis) in the eastern USA. Evidence suggests that the fly was introduced into the western USA sometime in the last 60 years. In addition to apple, R. pomonel...

  16. 1, 167188, 2006 Late Miocene River

    E-print Network

    Boyer, Edmond

    eED 1, 167­188, 2006 Late Miocene River Euphrates T. Demir et al. Title Page Abstract Introduction is the access reviewed discussion forum of eEarth Location of the River Euphrates in the Late Miocene; dating Miocene River Euphrates T. Demir et al. Title Page Abstract Introduction Conclusions References Tables

  17. Effect of hawthorn ( Crataegus oxycantha) crude extract and chromatographic fractions on multiple activities in a cultured cardiomyocyte assay

    Microsoft Academic Search

    S. R. Long; R. A. Carey; K. M. Crofoot; P. J. Proteau; T. M. Filtz

    2006-01-01

    Extracts of hawthorn (Crataegus oxycantha) have become popular herbal supplements for their well-recognized cardiotonic effects. Many commercial preparations have been used successfully in the treatment of congestive heart failure, although the active principles within these extracts have yet to be conclusively identified. Several hawthorn preparations were studied and found to have negative chronotropic effects in a cultured neonatal murine cardiomyocyte

  18. A Revised Interpretation of 3D Seismic Data, Hawthorne Army Depot, Nevada: FaultedBasin Reflections or Sill Intrusions?

    E-print Network

    (Blackwell et al., 1999). Surface evidence in Hawthorne indicates Reno Salt Lake City Hawthorne Las Vegas observations of domed overburden as well as crosscut stratigraphy. Models show that as intrusion proceeds, the magma pools to form the flat inner section and pushes up the overburden, forming a dome above the sill

  19. Abundances of apple maggot, Rhagoletis pomonella, across different areas in central Washington, with special reference to black-fruited hawthorns

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The apple maggot fly, Rhagoletis pomonella (Walsh), has infested native black-fruited hawthorn (mostly Crataegus douglasii Lindl.) in central Washington since at least 2003, but little is known about the fly’s ecology in hawthorns there. The main objective here was to determine adult and larval abu...

  20. Comparative protective effect of hawthorn berry hydroalcoholic extract, atorvastatin, and mesalamine on experimentally induced colitis in rats.

    PubMed

    Malekinejad, Hassan; Shafie-Irannejad, Vahid; Hobbenaghi, Rahim; Tabatabaie, Seyed Hamed; Moshtaghion, Seyed-Mehdi

    2013-07-01

    The protective effect of hydroalcoholic extract of hawthorn berries (HBE) on acetic acid (AA)-induced colitis in rats was investigated. Forty-two Wistar rats were divided into seven groups, including control and test groups (n=6). The control animals received saline, and the test animals were treated with saline (sham group), mesalamine (50 mg/kg; M group), atorvastatin (20 mg/kg; A group), HBE (100 mg/kg; H group), mesalamine and HBE (HM group), or atorvastatin plus HBE (HA group), 3 days before and a week after colitis induction. Colitis was induced by administration of 1 mL AA (4%) via a polyethylene catheter intrarectally. High-performance liquid chromatography analyses showed that HBE contained 0.13% and 0.5% oleanolic acid and ursolic acid, respectively. Elevated myeloperoxidase activity and lipid peroxidation were attenuated in the HA group. The H and HM groups showed marked reductions in colitis-induced decreases in total thiol molecules and body weight. The histopathological studies revealed that HBE decreased colitis-induced edema and infiltration of neutrophils. Our data suggest the anti-inflammatory and antioxidant effects of HBE and atorvastatin protect against AA-induced colitis. The anti-inflammatory effect of HBE may be attributable to its ability to decrease myeloperoxidase activity as a biomarker of neutrophil infiltration. PMID:23875899

  1. Identification of host fruit volatiles from domestic apple (Malus domestica), native black hawthorn (Crataegus douglasii) and introduced ornamental hawthorn (C. monogyna) attractive to Rhagoletis pomonella flies from the western United States.

    PubMed

    Cha, Dong H; Yee, Wee L; Goughnour, Robert B; Sim, Sheina B; Powell, Thomas H Q; Feder, Jeffrey L; Linn, Charles E

    2012-03-01

    The apple maggot fly, Rhagoletis pomonella, infests apple (Malus domestica) and hawthorn species (most notably the downy hawthorn, Crataegus mollis) in the eastern USA. Evidence suggests that the fly was introduced into the western USA sometime in the last 60 years. In addition to apple, R. pomonella also infests two species of hawthorns in the western USA as major hosts: the native black hawthorn (C. douglasii) and the introduced ornamental English hawthorn, C. monogyna. Apple and downy hawthorn-origin flies in the eastern USA use volatile blends emitted from the surface of their respective ripening fruit to find and discriminate among host trees. To test whether the same is true for western flies, we used coupled gas chromatography and electroantennographic detection (GC-EAD) and developed a 7-component apple fruit blend for western apple-origin flies, an 8-component black hawthorn fruit blend for flies infesting C. douglasii, and a 9-component ornamental hawthorn blend for flies from C. monogyna. Crataegus douglasii and C. monogyna-origin flies showed similar levels of upwind directed flight to their respective natal synthetic fruit blends in flight tunnel assays compared to whole fruit adsorbent extracts, indicating that the blends contain all the behaviorally relevant fruit volatiles to induce maximal response levels. The black and ornamental hawthorn blends shared four compounds in common including 3-methylbutan-1-ol, which appears to be a key volatile for R. pomonella populations in the eastern, southern, and western USA that show a preference for fruit from different Crataegus species. However, the blends also differed from one another and from domesticated apple in several respects that make it possible that western R. pomonella flies behaviorally discriminate among fruit volatiles and form ecologically differentiated host races, as is the case for eastern apple and hawthorn flies. PMID:22399441

  2. Fruit fate, frugivory, and fruit characteristics: a study of the hawthorn, Crataegus monogyna (Rosaceae)

    Microsoft Academic Search

    Rex Sallabanks

    1992-01-01

    The fate of fruits from a population of European hawthorn (Crataegus monogyna) in western Oregon, USA, was examined over a two-year period. Only one frugivore, the American robin (Turdus migratorius) foraged on the C. monogyna fruits, making this an unusually straightforward fruit-frugivore system. Dispersal efficiency was low, with an average 21% of seeds being dispersed (carried away from parent plants)

  3. The Repressive Nature of the Past: Hawthorne's "House of the Seven Gables."

    ERIC Educational Resources Information Center

    Loges, Max L.

    "The House of the Seven Gables" describes the problems that emerge when a family allows itself to become so locked into the traditions and sins of the past that each new generation becomes a slightly degenerated facsimile of the previous generation. Nathaniel Hawthorne manages this task by comparing Clifford, a descendent of a long line of…

  4. Population genetic structure of diploid sexual and polyploid apomictic hawthorns ( Crataegus ; Rosaceae) in the Pacific Northwest

    Microsoft Academic Search

    EUGENIA Y. Y. LO; SAŠA STEFANOVI?; TIMOTHY A. DICKINSON

    2009-01-01

    Polyploidy and gametophytic apomixis are two important and associated processes in plants. Many hawthorn species are polyploids and can reproduce both sexually and apomictically. However, the population genetic structure of these species is poorly understood. Crataegus douglasii is represented exclusively by self-compatible tetraploid pseudogamous apomicts across North America, whereas Crataegus suksdorfii found in the Pacific Northwest is known to include

  5. Curtobacterium flaccumfaciens Septic Arthritis following Puncture with a Coxspur Hawthorn Thorn ?

    PubMed Central

    Francis, Michelle J.; Doherty, Richard R.; Patel, Minoo; Hamblin, John F.; Ojaimi, Samar; Korman, Tony M.

    2011-01-01

    Curtobacterium species are recognized plant pathogens. We report the first well-documented case of Curtobacterium human infection, a child with septic arthritis following puncture with a Coxspur Hawthorn plant thorn. The organism isolated from synovial tissue and the plant thorn was identified as Curtobacterium flaccumfaciens by 16S rRNA gene sequence analysis. PMID:21562106

  6. Curtobacterium flaccumfaciens septic arthritis following puncture with a Coxspur Hawthorn thorn.

    PubMed

    Francis, Michelle J; Doherty, Richard R; Patel, Minoo; Hamblin, John F; Ojaimi, Samar; Korman, Tony M

    2011-07-01

    Curtobacterium species are recognized plant pathogens. We report the first well-documented case of Curtobacterium human infection, a child with septic arthritis following puncture with a Coxspur Hawthorn plant thorn. The organism isolated from synovial tissue and the plant thorn was identified as Curtobacterium flaccumfaciens by 16S rRNA gene sequence analysis. PMID:21562106

  7. Gall production on hawthorns caused by Gymnosporangium spp.in Hatay province, Turkey

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three hawthorn and related rust diseases caused by Gymnosporangium confusum on Crataegus monogyna, G. clavariiforme on C. orientalis, and G. sabinae on Pyrus communis were detected in Hatay province, Turkey. Gymnosporangium confusum was also found causing telial galls on Juniperus communis. Gymnospo...

  8. Mediterranean Miocene carbonates: facies models and diagenesis

    SciTech Connect

    Esteban, M.E.

    1987-11-01

    Miocene carbonates can bridge the gap between Holocene and older carbonate sequences, thus enhancing understanding of depositional and diagenetic patterns. Miocene carbonates can bridge this gap because of their similarity to Holocene counterparts and the ease of using these carbonates to reconstruct tectonic, paleogeographic, and paleoclimatic settings. In the Mediterranean, the Miocene provides a superb set of exposures and a wide variety of facies models in different geologic settings.

  9. 4, 535584, 2008 Early Miocene Asian

    E-print Network

    Paris-Sud XI, Université de

    CPD 4, 535­584, 2008 Early Miocene Asian monsoon Z. T. Guo et al. Title Page Abstract Introduction reorganization of Asian climate regime by the early Miocene Z. T. Guo 1 , B. Sun 1,2 , Z. S. Zhang 1,3 , S. Z Geosciences Union. 535 #12;CPD 4, 535­584, 2008 Early Miocene Asian monsoon Z. T. Guo et al. Title Page

  10. Lower Miocene sediments of central and western Ciscaucasia

    Microsoft Academic Search

    A. S. Stolyarov; E. I. Ivleva

    2006-01-01

    The composition, structure, and geochemical properties of the thickest, relatively deep-water Lower Miocene sediments developed\\u000a in western Ciscaucasia are considered. Of particular interest are materials from the Kuban superdeep borehole SG-12000 that\\u000a recovered the uppermost layers of the Maikop Group at 3148–3961 m in the central Indol-Kuban Trough west of Krasnodar. However,\\u000a the borehole did not penetrate the whole Lower

  11. Ammonium carbonate is more attractive than apple and hawthorn fruit volatile lures to Rhagoletis pomonella (Diptera: Tephritidae) in Washington State.

    PubMed

    Yee, Wee L; Nash, Meralee J; Goughnour, Robert B; Cha, Dong H; Linn, Charles E; Feder, Jeffrey L

    2014-08-01

    The apple maggot fly, Rhagoletis pomonella (Walsh), is an introduced, quarantine pest of apple (Malus domestica Borkhausen) in the Pacific Northwest of the United States. In the eastern United States where the fly is native, fruit volatiles have been reported to be more attractive than ammonia compounds to R. pomonella. However, the opposite may be true in the western United States. Here, we determined whether newly identified western apple and western hawthorn fruit volatiles are more attractive than ammonium carbonate (AC) to R. pomonella in apple, black hawthorn, and ornamental hawthorn trees in western Washington State. In all three host trees, sticky red sphere or yellow panel traps baited with AC generally caught more flies than traps baited with lures containing the four newly developed fruit blends (modified eastern apple, western apple, western ornamental hawthorn, and western black hawthorn) or two older blends (eastern apple and eastern downy hawthorn). Fruit volatiles also displayed more variation among trapping studies conducted at different sites, in different host trees, and across years than AC. The results imply that traps baited with AC represent the best approach to monitoring R. pomonella in Washington State. PMID:24915519

  12. Miocene benthic foraminiferal isotope records: A synthesis

    USGS Publications Warehouse

    Savin, S.M.; Douglas, R.G.; Keller, G.; Killingley, J.S.; Shaughnessy, L.; Sommer, M.A.; Vincent, E.; Woodruff, F.

    1981-01-01

    18O 16O and 13C 12C ratios of Miocene benthic foraminifera from a number of Atlantic, Pacific and Indian Ocean DSDP sites (71, 77B, 206, 208, 238, 279, 289, 296, 329, 357 and 366A) have been compiled. These provide a rather detailed history of Miocene deep water especially in the Pacific Ocean. Bottom-water temperatures rose during the early Miocene and then declined rapidly during the middle Miocene. This decline was accompanied by an increase in Antarctic glaciation. Late Miocene bottom temperatures and Antarctic ice volumes are inferred to be similar to today's, but exhibited some fluctuation. The early Miocene ocean was less thermally stratified at intermediate and abyssal depths while the late Miocene deep ocean had a thermal structure generally similar to the modern ocean. Foraminiferal carbon isotope ratios at most of the sites varied quasi-sympathetically throughout the Miocene. These variations must reflect comparable variations in the mean 13C 12C of marine HCO3-. However, the causes of such variations are not yet clear. ?? 1981.

  13. B. F. Skinner and T. N. Whitehead: A Brief Encounter, Research Similarities, Hawthorne Revisited, What Next?

    PubMed Central

    Claus, Calvin K

    2007-01-01

    B. F. Skinner and T. N. Whitehead recalled a personal interaction in 1934, with differing memories of the event. No evidence of other subsequent interactions or mutual citations has been found. Although they went their separate ways, three similarities in their research strategies have been found and are discussed. Elements of Whitehead's Hawthorne study and Skinner's concurrent, parallel work reveal that they both (a) introduced the cumulative curve to report data, (b) used a small number of subjects studied over time, and (c) used highly accurate recording devices. A few “afterwords” are offered on their lives and writings, and again, on the Hawthorne effect. A suggestion is made that a Skinner–Whitehead research approach might be useful in studying gambling behavior. PMID:22478490

  14. New primate genus from the Miocene of Argentina

    PubMed Central

    Tejedor, Marcelo F.; Tauber, Adán A.; Rosenberger, Alfred L.; Swisher, Carl C.; Palacios, María E.

    2006-01-01

    Killikaike blakei is a new genus and species of anthropoid from the late Early Miocene of southeastern Argentina based on the most pristine fossil platyrrhine skull and dentition known so far. It is part of the New World platyrrhine clade (Family Cebidae; Subfamily Cebinae) including modern squirrel (Saimiri) and capuchin monkeys (Cebus) and their fossil relatives known from Early to Middle Miocene and subrecent periods. Living cebines are relatively large-brained, adroit predatory foragers and live within complex social groups, and wild capuchins exhibit a wide range of behaviors associated with enhanced intelligence. We show that K. blakei lacks diagnostic derived characteristics of the lower face and premolar dentition that are shared by modern cebines, but its strongly vaulted frontal bone and capacious anterior cranial fossa indicate the early evolution of an enlarged forebrain. PMID:16567649

  15. First diatomyid rodent from the Early Miocene of Arabia

    NASA Astrophysics Data System (ADS)

    López-Antoñanzas, Raquel

    2011-02-01

    The Asian family Diatomyidae is known from the Early Oligocene to the present. Among living rodents, this group comprises only the recently discovered Laonastes aenigmamus from Laos. Fossil diatomyids are known from only a few sites, in which they are often rare. The discovery of Pierremus explorator gen. nov. sp. nov. in the Lower Miocene of As-Sarrar (Saudi Arabia) raises to ten the number of extinct diatomyid species recognized. Pierremus explorator is the first record of a diatomyid from the Afro-Arabian plate. This discovery provides evidence that, together with other rodents (ctenodactylids, zapodids…), the diatomyids took advantage of the corridor that was established between Afro-Arabia and Eurasia in Early Miocene times.

  16. Activity of hawthorn leaf and bark extracts in relation to biological membrane.

    PubMed

    W?och, Aleksandra; Kapusta, Ireneusz; Bielecki, Krzysztof; Oszmia?ski, Jan; Kleszczy?ska, Halina

    2013-07-01

    The aim of the study was to identify and determine the percent content of polyphenols in extracts from leaves and hawthorn bark, to examine the effect of the extracts on the properties of the biological membrane as well as to determine their antioxidant activity toward membrane lipids. In particular, a biophysical investigation was conducted on the effect of hawthorn extracts on the osmotic resistance and morphology of erythrocyte cells and on the packing of the heads of membrane lipids. Analysis of the polyphenol content of extracts used the HPLC method. Analysis of the polyphenol composition has shown a dominant share of procyanidins and epicatechin in both extracts. The research showed that the polyphenolic compounds contained in hawthorn extracts are incorporated mainly into the hydrophilic part of the erythrocyte membrane, inducing echinocyte shapes. They also diminish the packing order of the lipid polar heads of the membrane, as evidenced by the lowered generalized polarization values of Laurdan. The substances used induced increased osmotic pressure of erythrocytes, making them less sensitive to changes in osmotic pressure. The presence of the extract compounds in the outer hydrophilic part of the erythrocyte membrane, evidenced by examination of the shapes and packing in the hydrophilic part of membrane, indicates that the substances constitute a kind of barrier that protects the erythrocyte membrane against free radicals, while the membrane-bound extracts do not disturb the membrane structure and, thus, do not cause any side effects. PMID:23774969

  17. Allopolyploidy, diversification, and the Miocene grassland expansion

    PubMed Central

    Estep, Matt C.; McKain, Michael R.; Vela Diaz, Dilys; Zhong, Jinshun; Hodge, John G.; Hodkinson, Trevor R.; Layton, Daniel J.; Malcomber, Simon T.; Pasquet, Rémy; Kellogg, Elizabeth A.

    2014-01-01

    The role of polyploidy, particularly allopolyploidy, in plant diversification is a subject of debate. Whole-genome duplications precede the origins of many major clades (e.g., angiosperms, Brassicaceae, Poaceae), suggesting that polyploidy drives diversification. However, theoretical arguments and empirical studies suggest that polyploid lineages may actually have lower speciation rates and higher extinction rates than diploid lineages. We focus here on the grass tribe Andropogoneae, an economically and ecologically important group of C4 species with a high frequency of polyploids. A phylogeny was constructed for ca. 10% of the species of the clade, based on sequences of four concatenated low-copy nuclear loci. Genetic allopolyploidy was documented using the characteristic pattern of double-labeled gene trees. At least 32% of the species sampled are the result of genetic allopolyploidy and result from 28 distinct tetraploidy events plus an additional six hexaploidy events. This number is a minimum, and the actual frequency could be considerably higher. The parental genomes of most Andropogoneae polyploids diverged in the Late Miocene coincident with the expansion of the major C4 grasslands that dominate the earth today. The well-documented whole-genome duplication in Zea mays ssp. mays occurred after the divergence of Zea and Sorghum. We find no evidence that polyploidization is followed by an increase in net diversification rate; nonetheless, allopolyploidy itself is a major mode of speciation. PMID:25288748

  18. Allopolyploidy, diversification, and the Miocene grassland expansion.

    PubMed

    Estep, Matt C; McKain, Michael R; Vela Diaz, Dilys; Zhong, Jinshun; Hodge, John G; Hodkinson, Trevor R; Layton, Daniel J; Malcomber, Simon T; Pasquet, Rémy; Kellogg, Elizabeth A

    2014-10-21

    The role of polyploidy, particularly allopolyploidy, in plant diversification is a subject of debate. Whole-genome duplications precede the origins of many major clades (e.g., angiosperms, Brassicaceae, Poaceae), suggesting that polyploidy drives diversification. However, theoretical arguments and empirical studies suggest that polyploid lineages may actually have lower speciation rates and higher extinction rates than diploid lineages. We focus here on the grass tribe Andropogoneae, an economically and ecologically important group of C4 species with a high frequency of polyploids. A phylogeny was constructed for ca. 10% of the species of the clade, based on sequences of four concatenated low-copy nuclear loci. Genetic allopolyploidy was documented using the characteristic pattern of double-labeled gene trees. At least 32% of the species sampled are the result of genetic allopolyploidy and result from 28 distinct tetraploidy events plus an additional six hexaploidy events. This number is a minimum, and the actual frequency could be considerably higher. The parental genomes of most Andropogoneae polyploids diverged in the Late Miocene coincident with the expansion of the major C4 grasslands that dominate the earth today. The well-documented whole-genome duplication in Zea mays ssp. mays occurred after the divergence of Zea and Sorghum. We find no evidence that polyploidization is followed by an increase in net diversification rate; nonetheless, allopolyploidy itself is a major mode of speciation. PMID:25288748

  19. Influence of extraction technique on the anti-oxidative potential of hawthorn (Crataegus monogyna) extracts in bovine muscle homogenates.

    PubMed

    Shortle, E; O'Grady, M N; Gilroy, D; Furey, A; Quinn, N; Kerry, J P

    2014-12-01

    Six extracts were prepared from hawthorn (Crataegus monogyna) leaves and flowers (HLF) and berries (HB) using solid-liquid [traditional (T) (HLFT, HBT), sonicated (S) (HLFS, HBS)] and supercritical fluid (C) extraction (HLFC, HBC) techniques. The antioxidant activities of HLF and HB extracts were characterised using in vitro antioxidant assays (TPC, DPPH, FRAP) and in 25% bovine muscle (longissimus lumborum) homogenates (lipid oxidation (TBARS), oxymyoglobin (% of total myoglobin)) after 24h storage at 4°C. Hawthorn extracts exhibited varying degrees of antioxidant potency. In vitro and muscle homogenate (TBARS) antioxidant activity followed the order: HLFS>HLFT and HBT>HBS. In supercritical fluid extracts, HLFC>HBC (in vitro antioxidant activity) and HLFC?HBC (TBARS). All extracts (except HBS) reduced oxymyoglobin oxidation. The HLFS extract had the highest antioxidant activity in all test systems. Supercritical fluid extraction (SFE) exhibited potential as a technique for the manufacture of functional ingredients (antioxidants) from hawthorn for use in muscle foods. PMID:25170819

  20. Outcasts of the universe: a study of the scientists in Hawthorne's short stories. 

    E-print Network

    Decker, Joseph Patrick

    1963-01-01

    of the scholars mez. tioned in this para- graph are listed in the bi'oliography. kind of isolation is thei- punishment. Further, these scholars do not point out the cornectior betveer the Virtuoso of "P. Virtuoso's CoLlection" and Hawt'horne's other "empirics..." (II, 548), Other exhibits, by th . i very p essence, con- firm the guest's feelings about his host. . &hen tne Virtuoso points out tne iron z sk, in which ne takes prid. e, the guest grows sick at heart because this relic "had, shut out a human...

  1. Constitutive and herbivore?induced volatiles in pear, alder and hawthorn trees

    Microsoft Academic Search

    Petru Scutareanu; Jan Bruin; Maarten A. Posthumus; Bas Drukker

    2003-01-01

    Summary.   Qualitative and quantitative differences among pear cultivars were found\\u000a in constitutive and Cacopsylla-induced volatiles, depending on\\u000a experimental treatment of the trees (i.e., uninfested and partly or\\u000a completely infested by psyllids). Blend differences were also found\\u000a between pear cultivars and wild-type pear, alder and hawthorn–the\\u000a latter trees are frequently present in pear orchard\\u000a hedgerows. ¶Interesting differences were found in the

  2. The late early Miocene Sabine River

    SciTech Connect

    Manning, E. (Louisiana State Univ., Baton Rouge (USA))

    1990-09-01

    Work on a new late early Miocene vertebrate fossil site, in a paleochannel deposit of the upper Carnahan Bayou Member of the lower Fleming Formation, has revealed unexpected data on the course and nature of the Sabine River of that time. Screen washing for smaller vertebrate remains at the site, just west of the Sabine River in Newton County, central eastern Texas, has resulted in the recovery of early Permian, Early Cretaceous, Late Cretaceous (Maestrichtian), Paleocene/Eocene, late Eocene, and Oligocene/Miocene fossils, in addition to the main early Miocene fauna. The reworked fossils, as well as distinctive mineral grains, show that the late early Miocene Sabine River was connected to the Texas/Oklahoma/Arkansas boundary section of the Red River, as well as to rivers draining the southern Ouachita Mountains. These rivers must have joined the Texas/Louisiana boundary section of the Sabine River somewhere in northwest Louisiana at that time. This suggests that the Louisiana section of the present Red River pirated the Texas/Oklahoma/Arkansas boundary section of the river some time after the early Miocene. The preservation of recognizable fossils transported hundreds of miles in a large river itself requires explanation. It is speculated here that the late early Miocene Sabine River incorporated a large amount of the then recently deposited volcanic ash from the Trans-Pecos Volcanic Field. Montmorillonite clay from the altered volcanic ash would have made the river very turbid, which could have allowed coarse sand-sized particles to be carried in the suspended load of the river, rather than in its bed load (where they would have been destroyed by the rolling chert gravel). Additional evidence for such long-distance fossil transport in the late early Miocene rivers of the western Gulf Coastal Plain comes from the abundant Cretaceous fossils of the upper Oakville Formation of southeast Texas and the Siphonina davisi zone of the southeast Texas subsurface.

  3. A sphenodontine (Rhynchocephalia) from the Miocene of New Zealand and palaeobiogeography of the tuatara (Sphenodon)

    PubMed Central

    Jones, Marc E.H.; Tennyson, Alan J.D.; Worthy, Jennifer P.; Evans, Susan E.; Worthy, Trevor H.

    2009-01-01

    Jaws and dentition closely resembling those of the extant tuatara (Sphenodon) are described from the Manuherikia Group (Early Miocene; 19–16 million years ago, Mya) of Central Otago, New Zealand. This material is significant in bridging a gap of nearly 70 million years in the rhynchocephalian fossil record between the Late Pleistocene of New Zealand and the Late Cretaceous of Argentina. It provides the first pre-Pleistocene record of Rhynchocephalia in New Zealand, a finding consistent with the view that the ancestors of Sphenodon have been on the landmass since it separated from the rest of Gondwana 82–60?Mya. However, if New Zealand was completely submerged near the Oligo-Miocene boundary (25–22?Mya), as recently suggested, an ancestral sphenodontine would need to have colonized the re-emergent landmass via ocean rafting from a currently unrecorded and now extinct Miocene population. Although an Early Miocene record does not preclude that possibility, it substantially reduces the temporal window of opportunity. Irrespective of pre-Miocene biogeographic history, this material also provides the first direct evidence that the ancestors of the tuatara, an animal often perceived as unsophisticated, survived in New Zealand despite substantial local climatic and environmental changes. PMID:19203920

  4. Aquifer characteristics and water quality of Miocene–Pleistocene sediments, Kuwait

    Microsoft Academic Search

    F. M. Al-Ruwaih; H. A. Qabazard

    2005-01-01

    Al-Atraf is one of the water well fields of Kuwait supplying Kuwait City with the brackish groundwater obtained from the Kuwait Group aquifer of Miocene–Pleistocene age. The study determined the hydrogeological and hydrochemical characteristics of the groundwater in order to identify the major chemical processes that influence the groundwater quality of the study area. The results of the aquifer test

  5. Cementation in Oligo-Miocene non-tropical shelf limestones, Otway Basin, Australia

    Microsoft Academic Search

    Stelios Nicolaides

    1995-01-01

    The Oligocene to Miocene Heytesbury Group of the Otway Basin, southeastern Australia, is a non-tropical carbonate shelf succession. This subsurface stratigraphic succession consists of bioclastic grainstones to mudstones containing bryozoa, benthonic and planktonic foraminifera, echinoderms, brachiopods, and molluscs. The basal bryozoa-dominated Clifton Formation was deposited in relatively shallow waters. The overlying Gellibrand Marl, rich in planktonic foraminifera and bryozoa, formed

  6. Norcholestane in Miocene Onnagawa siliceous sediments, Japan

    SciTech Connect

    Suzuki, Noriyuki; Sampei, Yoshikazu; Koga, Osamu (Shimane Univ. (Japan))

    1993-09-01

    A significant amount of 24-norcholestane with 20R, 5[alpha](H), 14[alpha](H), 17[alpha](H) stereochemistry is often found in marine siliceous sediments of the Middle Miocene Onnagawa Formation, Japan. Some Onnagawa siliceous sediments are abnormally abundant in 24-norcholestane. The primary production in the northeastern Japan Sea during the Middle Miocene was markedly increased due to the invasion of nutrient-rich cold seawater from the north accompanied by the tectonic opening of the Japan Sea. 24-norcholestane in high relative abundance is derived mainly from the marine diatoms which were enhanced during this event. The drastic ecological change caused by rapid tectonic opening of the Japan Sea and global climatic deterioration during Middle Miocene time is suggested to be influential in the formation of 24-norcholestane-rich Onnagawa siliceous sediments.

  7. Miocene precursors to Great Barrier Reef

    SciTech Connect

    Davies, P.J.; Symonds, P.A.; Feary, D.A.; Pigram, C.

    1988-01-01

    Huge reefs of Miocene age are present in the Gulf of Papua north of the present-day Great Barrier Reef and to the east on the Marion and Queensland Plateaus. In the Gulf of Papua, Miocene barrier reefs formed the northern forerunner of the Great Barrier Reef, extending for many hundreds of kilometers along the eastern and northern margin of the Australian craton within a developing foreland basin. Barrier reefs, slope pinnacle reefs, and platform reefs are seen in seismic sections and drill holes. Leeside talus deposits testify to the high energy impinging on the eastern margin of these Miocene reefs. The Queensland Plateau is a marginal plateau east of the central Great Barrier Reef and separated from it by a rift trough. Miocene reefs occupied an area of about 50,000 km/sup 2/ and grew on salt-controlled highs on the western margin of the plateau and on a regional basement high extending from the platform interior to its southern margin. Reef growth has continued to the present day, although two major contractions in the area covered by reefs occurred during the Miocene. The Marion Plateau is present directly east of the Great Barrier Reef and during the Micoene formed a 30,000-km/sup 2/ platform with barrier reefs along its northern margin and huge platform reefs and laggons on the platform interior. These reefs grew on a flat peneplained surface, the whole area forming a large shallow epicontinental sea. In all three areas, the middle Miocene formed the acme of reef expansion in the region.

  8. Transcript Assembly and Quantification by RNA-Seq Reveals Differentially Expressed Genes between Soft-Endocarp and Hard-Endocarp Hawthorns

    PubMed Central

    Zhang, Feng; Liu, Zhongchi; Li, Xiaoming; Li, Wenran; Ma, Yue; Li, He; Liu, Yuexue; Zhang, Zhihong

    2013-01-01

    Hawthorn (Crataegus spp.) is an important pome with a long history as a fruit, an ornamental, and a source of medicine. Fruits of hawthorn are marked by hard stony endocarps, but a hawthorn germplasm with soft and thin endocarp was found in Liaoning province of China. To elucidate the molecular mechanism underlying the soft endocarp of hawthorn, we conducted a de novo assembly of the fruit transcriptome of Crataegus pinnatifida and compared gene expression profiles between the soft-endocarp and the hard-endocarp hawthorn varieties. De novo assembly yielded 52,673 putative unigenes, 20.4% of which are longer than 1,000 bp. Among the high-quality unique sequences, 35,979 (68.3%) had at least one significant match to an existing gene model. A total of 1,218 genes, represented 2.31% total putative unigenes, were differentially expressed between the soft-endocarp hawthorn and the hard-endocarp hawthorn. Among these differentially expressed genes, a number of lignin biosynthetic pathway genes were down-regulated while almost all the flavonoid biosynthetic pathway genes were strongly up-regulated, concomitant with the formation of soft endocarp. In addition, we have identified some MYB and NAC transcription factors that could potentially control lignin and flavonoid biosynthesis. The altered expression levels of the genes encoding lignin biosynthetic enzymes, MYB and NAC transcription factors were confirmed by quantitative RT-PCR. This is the first transcriptome analysis of Crataegus genus. The high quality ESTs generated in this study will aid future gene cloning from hawthorn. Our study provides important insights into the molecular mechanisms underlying soft endocarp formation in hawthorn. PMID:24039819

  9. RESEARCH PAPER A Middle Miocene endemic freshwater mollusc assemblage

    E-print Network

    Zuschin, Martin

    RESEARCH PAPER A Middle Miocene endemic freshwater mollusc assemblage from an intramontane Alpine online: 1 September 2011 Ó Springer-Verlag 2011 Abstract The mollusc fauna of the early Middle Miocene settings. Among the gastropods, only Theodoxus crenulatus (Klein, 1853) is known from other Miocene

  10. Middle Miocene tectonic boundary conditions for use in climate models

    E-print Network

    Müller, Dietmar

    Middle Miocene tectonic boundary conditions for use in climate models N. Herold, M. Seton, and R. D model boundary conditions. We present a middle Miocene paleotopographic and paleobathymetric is reconstructed through application of an age-depth relationship to a middle Miocene global digital isochron map

  11. Modeling the Miocene climatic optimum: Ocean circulation N. Herold,1

    E-print Network

    Müller, Dietmar

    Modeling the Miocene climatic optimum: Ocean circulation N. Herold,1 M. Huber,2 R. D. Müller,1) forced with early to middle Miocene ($20­14 Ma) topography, bathymetry, vegetation and modern CO2 is weaker in the Miocene due to weaker midlatitude westerlies in the southern hemisphere, caused by lowering

  12. Preserved lignin structures in Miocene-aged lignite lithotypes, Bulgaria

    E-print Network

    Paris-Sud XI, Université de

    Preserved lignin structures in Miocene-aged lignite lithotypes, Bulgaria M. Stefanova, O. Maman, B, Orleans Cedex 2, France Abstract Contents of preserved lignin structures in Miocene-aged lignite research is devoted to Miocene-aged lignite lithotypes. The contents of lignin- derived phenols in products

  13. Published online 7 October 2004 Multiple Miocene Melastomataceae dispersal

    E-print Network

    Renner, Susanne

    Published online 7 October 2004 Multiple Miocene Melastomataceae dispersal between Madagascar from Africa during the Miocene. Medinilla, with some 70 species in Madagascar and two in Africa, too, arrived during the Miocene, but from Asia. Gravesia, with 100 species in Madagascar and four in east

  14. Climate model sensitivity to changes in Miocene paleotopography

    E-print Network

    Müller, Dietmar

    Climate model sensitivity to changes in Miocene paleotopography N. HEROLD1 , Y. YOU1,2 *, R. D. MU, NSW 2006, Australia. The Middle Miocene Climatic Optimum (MMCO), which occurred between 17 and 15 Ma Land Model (CLM) to changes in Middle Miocene paleotopography using prescribed sea-surface temperatures

  15. A farm-scale evaluation of the influence of hedgerow cutting frequency on hawthorn ( Crataegus monogyna) berry yields

    Microsoft Academic Search

    P. J Croxton; T. H Sparks

    2002-01-01

    Hawthorn Crataegus monogyna is the dominant hedgerow species in the UK and has the potential to produce an abundance of berries (haws). These berries provide an important food resource for many animals through the winter. Experimental studies have shown a strong influence of hedgerow management on berry production and this study examines whether that influence extends to farm-scale hedgerow management.

  16. A comparison of the composition of epicuticular wax from red raspberry ( Rubus idaeus L.) and hawthorn ( Crataegus monogyna Jacq.) flowers

    Microsoft Academic Search

    D. Wynne Griffiths; Graeme W Robertson; Tom Shepherd; A. Nicholas E Birch; Stuart C Gordon; J. A. Trefor Woodford

    2000-01-01

    Epicuticular waxes have been characterised from the flowers of raspberry and hawthorn, on both of which adult raspberry beetles (Byturus tomentosus) can feed. The flower wax from both species had similar alkane profiles and also contained long-chain alcohols, aldehydes and fatty acids. The range of the carbon numbers detected for these classes of compounds was broadly similar in both but

  17. The Solar Activity in the Miocene Period In this Subthesis we study the solar activity in the Miocene (or Triassic)

    E-print Network

    The Solar Activity in the Miocene Period In this Subthesis we study the solar activity in the Miocene (or Triassic) period. Measurements of the thickness of the annual tree­rings of petrified trees in pre­historic times. Study of annual tree­ rings of 12 different petrified trees from the Miocene (or

  18. Murky details of the Miocene Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Herold, N. K.; Huber, M.; Shevenell, A.; Müller, D.

    2013-12-01

    We examine Atlantic Ocean circulation during the Miocene based on published modelling and data. It has long been recognised that the Atlantic Ocean played a key role in climate changes throughout the Quaternary and determining whether this was the case earlier in the Cenozoic may be important for understanding the details of Miocene climate evolution. Current geochemical, sedimentological and micropaleontologic evidence allows for multiple interpretations of deep water activity, which is further hampered by a lack of precise dating of ocean gateway closures. Previous ocean modelling studies have shown strong increases in deep water formation due to closure of the Panama gateway but have disagreed on the oceanographic importance of the Tethys gateway and bathymetry of the far North Atlantic. This combination of ambiguous data and conflicting modelling results leaves the current state of knowledge of the Miocene ocean lacking. We propose several avenues of research to improve our knowledge of the Miocene Atlantic Ocean, which will ultimately improve our understanding of its response to climate change and vice versa.

  19. Isolation and quantification of oligomeric and polymeric procyanidins in leaves and flowers of Hawthorn (Crataegus spp.).

    PubMed

    Hellenbrand, N; Sendker, J; Lechtenberg, M; Petereit, F; Hensel, A

    2015-07-01

    Proanthocyanidins (PAs) constitute a class of polyphenols with flavan-3-ols as monomeric building blocks. These polyphenols are mostly quantified by colorimetric methods or by chromatographic determination of monomeric flavan-3-ols or low molecular oligomers as lead compounds. No reliable analytical methods are available for unambiguous identification of the homologues series of oligo- and polymeric PAs. For Hawthorn leaf and flower (Crataegi folium cum flore) from Crataegus spp. (Rosaceae) a protocol for preparative isolation of oligomeric and polymeric PAs from an acetone-water extract was developed, yielding procyanidin reference clusters with defined degree of polymerization (DP) from 2 to 10 besides a procyanidin-polymer. Identity and purity of these clusters were proven by HPLC, MS and in part NMR studies. For identification and quantification from Hawthorn an ICH-Q2 validated UHPLC method with fluorimetric detection and less than 10min runtime was developed. The method enabled quantification of procyanidin clusters with DP from 2 to 10 besides the polymer fraction. Batch analysis revealed procyanidin contents of about 20 to 45mg/g from a homologues series of oligomeric PAs and about 50% of polymer fraction. Monitoring of procyanidin distribution during seasonal growth of fresh plants of Crataegus monogyna showed more or less constant contents between 20 and 55mg/g dry weight of oligomeric procyanidins during the growing season in the different plant organs with strong accumulation in the flowers and fruits (55mg/g dry weight). From these data it can be speculated that procyanidins serve as part of the plants defense system in the reproductive organs of the plant. PMID:25917901

  20. Paleomagnetism of Miocenic Rocks Around Chalcatzingo, Morelos, Mexico: A Revaluation

    NASA Astrophysics Data System (ADS)

    Vazquez-Duarte, A.; Bohnel, H.; Yutsis, V.

    2009-05-01

    The Chalcatzingo domes southeast of Mexico City have been recently 40Ar/39Ar dated to be around 20.7 Ma old. These rocks and the surrounding Tepexco Volcanic Group are defined in a previous study as showing strongly discordant paleomagnetic directions, about 50 west from the expected Miocene geomagnetic field direction; which prompted the hypothesis of a counter clockwise crustal block rotation, related to a regional left lateral fault system along the Transmexican Volcanic Belt. This rotation is the largest proposed so far for central Mexico, and it is in contrast to data from the nearby Basin of Mexico, which are concordant with the expected field directions. In view of the limited previous sampling and relatively complex remanence record, we have re-sampled the Chalcatzingo and Tepexco rocks to verify the validity of the proposed block rotation. For that purpose samples were collected from 26 sites. Reflected light and scanning electron microscopy were used to determine composition and texture of magnetic minerals, and IRM acquisition and thermomagnetic experiments to determine the rock magnetic properties. Detailed demagnetization was carried out using mainly the AF method to determine the characteristic remanence directions, to calculate site mean directions and VGPs. These are compared to the Miocene reference direction and pole for stable North America, and interpreted in terms of potential tectonic movements of the study area.

  1. Postharvest stability of antioxidant compounds in hawthorn and cornelian cherries at room and refrigerator temperatures—Comparison with blackberries, white and red grapes

    Microsoft Academic Search

    Dunja Šamec; Jasenka Piljac-Žegarac

    2011-01-01

    Antioxidant capacity (DPPH, ABTS and FRAP assays), as well as total phenol (TP), total flavonoid (TF) and total anthocyanin (TA) contents of hawthorn (Crataegus monogyna L.), cornelian cherries (Cornus mas), blackberries (Rubus fruticosus) and white and red grapes (Vitis vinifera L.) were monitored during postharvest storage at room and refrigerator temperatures. Hawthorn exhibited the highest initial TP (891.15±10.83mg GAE\\/100g FW)

  2. Structural analysis of proanthocyanidins isolated from fruit stone of Chinese hawthorn with potent antityrosinase and antioxidant activity.

    PubMed

    Chai, Wei-Ming; Chen, Chih-Min; Gao, Yu-Sen; Feng, Hui-Ling; Ding, Yu-Mei; Shi, Yan; Zhou, Han-Tao; Chen, Qing-Xi

    2014-01-01

    Proanthocyanidins were isolated from fruit stone of Chinese hawthorn (Crataegus pinnatifida Bge. var. major N.E.Br.). Their structures were analyzed and elucidated by methods of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and high performance liquid chromatography electrospray ionization mass spectrometry (HPLC-ESI-MS). The results demonstrated that these compounds are complicated mixtures of homo- and heteropolymers consisting of procyanidin/procyanidin gallate and prodelphinidin. They possessed structural heterogeneity in monomer units, polymer length, and interflavan linkage (A-type and B-type). Their antityrosinase and antioxidant activity were then investigated. The results revealed that they can inhibit tyrosinase activities, including the monophenolase activity and the diphenolase activity. In addition, proanthocyanidins possessed potent antioxidant activity. Our studies revealed that proanthocyanidins isolated from fruit stone of Chinese hawthorn may be applied in food, agriculture, pharmaceutical, and cosmetic industries. PMID:24313351

  3. Diagenesis of Miocene sandstones, South Louisiana

    E-print Network

    Smith, Richard Lee

    1983-01-01

    Many of these traps may be diagenetically controlled since diagenesis alters the composition and texture of sandstones. The Miocene section of South Louisiana is one of the most pro- lific hydrocarbon producing trends in the Gul Coast province. Various... deposited in coastal and shallow marine environments, mostly in deltaic depo- centers. Interpretation of the depositional environment of the sand- stones examined in this study is a primary ob]ective since diagenesis may be controlled by the environment...

  4. Abundance of apple maggot, Rhagoletis pomonella, across different areas in central Washington, with special reference to black-fruited hawthorns.

    PubMed

    Yee, Wee L; Klaus, Michael W; Cha, Dong H; Linn, Charles E; Goughnour, Robert B; Feder, Jeffrey L

    2012-01-01

    The apple maggot fly, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), infests non-commercial apple (Malus domestica (Borkh.) Borkh.) and native black-fruited hawthorns (mostly Crataegus douglasii Lindl.) in central Washington, but little has been published on the abundance of the fly in this region. In this paper, the abundance of R. pomonella across different sites near apple-growing areas in central Washington is documented in order to assess the threat of the fly to commercial apple orchards. The fly was first detected on traps in Klickitat, Yakima, and Kittitas Counties in 1981, 1995, and 1997, respectively. From 1981-2010 in Kittitas and Yakima Counties, only 0 to 4.7% of traps on apple, crabapple, and hawthorn trees were positive for flies, whereas in Klickitat County, located farther from commercial apple orchards, 0 to 41.9% of traps were positive. In 2008, in Yakima County and Goldendale in Klickitat County, 7.8% of black-fruited hawthorn trees were infested, with 0 to 0.00054 larvae per fruit. In 2010, in Kittitas and Yakima Counties and Goldendale in Klickitat County, 25.0% of C. douglasii trees were infested, with 0.00042 to 0.00248 larvae per fruit. In 2010, in a remote forested area of Klickitat County far from commercial apple orchards, 94.7% of C. douglasii trees were infested, with 0.20813 larvae per fruit. Overall results suggest R. pomonella is unlikely to develop high populations rapidly near major commercial apple-growing areas in central Washington, including in black-fruited hawthorns, increasing chances it can be kept out of commercial orchards. PMID:23451979

  5. Abundance of Apple Maggot, Rhagoletis pomonella, Across Different Areas in Central Washington, with Special Reference to Black-Fruited Hawthorns

    PubMed Central

    Yee, Wee L.; Klaus, Michael W.; Cha, Dong H.; Linn, Charles E.; Goughnour, Robert B.

    2012-01-01

    The apple maggot fly, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), infests non-commercial apple (Malus domestica (Borkh.) Borkh.) and native black-fruited hawthorns (mostly Crataegus douglasii Lindl.) in central Washington, but little has been published on the abundance of the fly in this region. In this paper, the abundance of R. pomonella across different sites near apple-growing areas in central Washington is documented in order to assess the threat of the fly to commercial apple orchards. The fly was first detected on traps in Klickitat, Yakima, and Kittitas Counties in 1981, 1995, and 1997, respectively. From 1981–2010 in Kittitas and Yakima Counties, only 0 to 4.7% of traps on apple, crabapple, and hawthorn trees were positive for flies, whereas in Klickitat County, located farther from commercial apple orchards, 0 to 41.9% of traps were positive. In 2008, in Yakima County and Goldendale in Klickitat County, 7.8% of black-fruited hawthorn trees were infested, with 0 to 0.00054 larvae per fruit. In 2010, in Kittitas and Yakima Counties and Goldendale in Klickitat County, 25.0% of C. douglasii trees were infested, with 0.00042 to 0.00248 larvae per fruit. In 2010, in a remote forested area of Klickitat County far from commercial apple orchards, 94.7% of C. douglasii trees were infested, with 0.20813 larvae per fruit. Overall results suggest R. pomonella is unlikely to develop high populations rapidly near major commercial apple-growing areas in central Washington, including in black-fruited hawthorns, increasing chances it can be kept out of commercial orchards. PMID:23451979

  6. The pharmacokinetics of C-glycosyl flavones of Hawthorn leaf flavonoids in rat after single dose oral administration

    Microsoft Academic Search

    L. Y. Ma; R. H. Liu; X. D. Xu; M. Q. Yu; Q. Zhang; H. L. Liu

    2010-01-01

    Hawthorn leaf flavonoids (HLF) are used in the treatment of cardiovascular diseases. Various potential pharmacodynamic effects have been observed for vitexin-4?-O-glucoside (VOG) and vitexin-2?-O-rhamnoside (VOR) which are the main constituents of HLF. The aim of this study was to investigate the pharmacokinetics of VOG and VOR when a single dose of HLF was administrated orally. The levels of VOG and

  7. New hominoid skull material from the Miocene of Pakistan

    Microsoft Academic Search

    David Pilbeam

    1982-01-01

    Neogene hominoid cranial material is regrettably scarce, especially from the middle and late Miocene. Between the 18-Myr-old virtually complete early Miocene Proconsul africanus skull from Rusinga1 and the 3-4-Myr-old Hadar hominoid cranial material2, the only significant large (non-hylobatid) hominoid facial or cranial specimens are those from the late Miocene Salonika in Greece3, Yassiören in Turkey4, Lufeng in China5, the possibly

  8. Miocene to Pliocene vegetation reconstruction and climate estimates in the Iberian Peninsula from pollen data

    E-print Network

    Jiménez-Moreno, Gonzalo

    Miocene to Pliocene vegetation reconstruction and climate estimates in the Iberian Peninsula from online 15 August 2009 Keywords: Miocene Pliocene Iberian Peninsula pollen vegetation climate change Pollen analysis of Miocene and Pliocene sediments from the Iberian Peninsula shows a progressive

  9. ANCYLOTHERIUM PENTELICUM (PERISSODACTYLA, MAMMALIA) FROM THE UPPER MIOCENE OF CENTRAL AND WESTERN

    E-print Network

    Paris-Sud XI, Université de

    ANCYLOTHERIUM PENTELICUM (PERISSODACTYLA, MAMMALIA) FROM THE UPPER MIOCENE OF CENTRAL AND WESTERN (Perissodactyla, Mammalia) from the Upper Miocene of central and western Turkey. Ancylotherium pentelicum, before its extinction. KEYWORDS: CHALICOTHERIIDAE, ANCYLOTHERIUM, LATE MIOCENE, PALEOENVIRONMENT, TURKEY

  10. The Late Miocene paleogeography of the Amazon Basin and the evolution of the Amazon River system

    E-print Network

    Bermingham, Eldredge

    The Late Miocene paleogeography of the Amazon Basin and the evolution of the Amazon River system Keywords: Amazon basin Amazon River Late Miocene Paleogeography Paleoecology fossil vertebrates palinology

  11. Distributional patterns of decapod crustaceans in the circum-Mediterranean area during the Oligo-Miocene

    NASA Astrophysics Data System (ADS)

    Hyžný, Matúš

    2015-04-01

    During the Oligocene and Miocene, the circum-Mediterranean area was a complex network of (mostly) shallow marine basins. Significant biogeographic differentiation of this area has been documented (Harzhauser et al. 2007), mainly during the Miocene, when connections between Proto-Mediterranean, Paratethys and Proto-Indo-West Pacific were intermittently opening and closing. These seaways allowed migration of marine faunas. Distributional patterns has so far been discussed for several different animal groups, especially for molluscs (e.g. Studencka et al. 1998; Harzhauser et al. 2002, 2003, 2007). To test these patterns with decapod crustaceans, a database has been compiled including all previously published Oligocene and Miocene decapod occurrences and newly gathered data from examined material deposited in the institutional collections. Decapod associations have been significant components of marine habitats since the Mesozoic times with ever-increasing importance throughout the Cenozoic. Müller (1979) argued that brachyuran decapods are among the best zoogeographical indicators. Although decapods were used as such indicators before (e.g. Schweitzer 2001; Feldmann & Schweitzer 2006), no detailed analysis of the circum-Mediterranean taxa has been conducted so far. Based on proposed anti-estuarine circulation pattern, decapods originated in the Proto-Mediterranean, and migrated both into the North Sea and the Paratethys. Moreover, during the Early Miocene the Rhine Graben served as a connection between the North Sea and the Paratethys which enabled faunal exchange. The Middle Miocene Proto-Mediterranean and Paratethys decapod assemblages as taken together were relatively homogeneous, although distinct due to increasing rate of endemites in the Paratethys during the Miocene. The research has been supported by FWF: Lise Meitner Program M 1544-B25. References Feldmann R.M. & Schweitzer C.E. 2006: Paleobiogeography of Southern Hemisphere decapod Crustacea. J. Paleontol. 80, 83-103. Harzhauser M., Kroh A., Mandic O., Piller W.E., Göhlich U., Reuter M. & Berning B. 2007: Biogeographic responses to geodynamics: a key study all around the Oligo-Miocene Tethyan Seaway. Zool. Anz. 246, 241-256. Harzhauser M., Mandic O. & Zuschin M. 2003: Changes in Paratethyan marine molluscs at the Early/Middle Miocene transition: diversity, palaeogeography and palaeoclimate. Acta Geol. Pol. 53, 323-339. Harzhauser M., Piller W.E. & Steininger F.F. 2002: Circum-Mediterranean Oligo/Miocene Biogeographic Evolution - the Gastropods' Point of View. Palaeogeogr., Palaeoclimatol., Palaeoecol. 183, 103-133. Müller P. 1979: The Indo-West-Pacific character of the Badenian decapod crustaceans of the Paratethys. In: VII International Congress on Mediterranean Neogene. Athens, September 27-October 2. Ann. Géol. Pays Hellén., Tome hors série 2, 865-869. Schweitzer C.E. 2001: Paleobiogeography of Cretaceous and Tertiary decapod crustaceans of the North Pacific Ocean. J. Paleontol. 75, 808-826. Studencka B., Gontsharova I.A. & Popov S.V. 1998: The bivalve faunas as a basis for reconstruction of the Middle Miocene history of the Paratethys. Acta Geol. Pol. 48, 285-342.

  12. New Miocene scarabeid and hymenopterous nests and early miocene (santacrucian) paleoenvironments, patagonian Argentina

    Microsoft Academic Search

    Jorge F. Genise; Thomas M. Bown

    1994-01-01

    Three new trace fossils are described from Miocene paleosols of southern Argentina. Celliforma pinturensis, n. ichnosp. and Celliforma rosellii, n. ichnosp. are interpreted as cells of digging bees, possibly Anthophoridae, and Coprinisphaerafrenguellii, n. ichnosp. are brood balls of dung?beetles. Both burrowing bees and dung?beetles are common nesters in relatively open areas, confirming previous reconstructions of the paleoenvironment of the Pinturas

  13. Paleomagnetic evidence for the Miocene counter-clockwise rotation of Northeast Japan-rifting process of the Japan arc

    Microsoft Academic Search

    Yo-Ichiro Otofuji; Takaaki Matsuda; Susumu Nohda

    1985-01-01

    Paleomagnetic results have been obtained from more than 700 oriented samples in igneous rocks of Cretaceous to Miocene age from Northeast Japan. The remanent magnetizations of welded tuffs with age between 32 Ma and 21 Ma old from 17 widely distributed sampling sites in Northeast Japan are fairly well grouped with a mean of D = -41.2°, I = 56.5°,

  14. Late Miocene magnetostratigraphy, biostratigraphy and cyclostratigraphy in the Mediterranean

    Microsoft Academic Search

    W. Krijgsman; F. J. Hilgen; C. G. Langereis; A. Santarelli; W. J. Zachariasse

    1995-01-01

    A new chronology for the late Miocene of the Mediterranean is presented by combining magnetostratigraphic, biostratigraphic (planktonic foraminifera and dinoflagellates) and cyclo-stratigraphic data. Long and continuous upper Miocene sections on Gavdos (Metochia section) and Sicily (Gibliscemi section) display cyclic alternations of homogeneous marls and sapropels and can be correlated on the basis of their distinct cyclic patterns. The Metochia section

  15. Ventilation of the Miocene Arctic Ocean: An idealized model study

    Microsoft Academic Search

    Bijoy Thompson; Johan Nilsson; Jonas Nycander; Martin Jakobsson; Kristofer Döös

    2010-01-01

    A model study of an idealized early Miocene Arctic Ocean has been undertaken. The work is motivated by the first drill core retrieved from the Lomonosov Ridge in the central Arctic Ocean, which suggests a transition from anoxic to oxic condition during the early Miocene, a feature presumably related to the opening of the Fram Strait. Here, the ventilation in

  16. Miocene Shark and Batoid Fauna from Nosy Makamby (Mahajanga Basin, Northwestern Madagascar)

    PubMed Central

    Andrianavalona, Tsiory H.; Ramihangihajason, Tolotra N.; Rasoamiaramanana, Armand; Ward, David J.; Ali, Jason R.; Samonds, Karen E.

    2015-01-01

    Madagascar is well known for producing exceptional fossils. However, the record for selachians remains relatively poorly known. Paleontological reconnaissance on the island of Nosy Makamby, off northwest Madagascar, has produced a previously undescribed assemblage of Miocene fossils. Based on isolated teeth, ten taxonomic groups are identified: Otodus, Carcharhinus, Galeocerdo, Rhizoprionodon, Sphyrna, Hemipristis, Squatina, Rostroraja, Himantura and Myliobatidae. Six are newly described from Madagascar for the Cenozoic (Galeocerdo, Rhizoprionodon, Sphyrna, Squatina, Rostroraja and Himantura). In association with these specimens, remains of both invertebrates (e.g., corals, gastropods, bivalves) and vertebrates (e.g., bony fish, turtles, crocodylians, and sirenian mammals) were also recovered. The sedimentary facies are highly suggestive of a near-shore/coastal plain depositional environment. This faunal association shares similarities to contemporaneous sites reported from North America and Europe and gives a glimpse into the paleoenvironment of Madagascar’s Miocene, suggesting that this region was warm, tropical shallow-water marine. PMID:26075723

  17. Quantifying the Hawthorne Effect in Hand Hygiene Compliance Through Comparing Direct Observation With Automated Hand Hygiene Monitoring.

    PubMed

    Hagel, Stefan; Reischke, Jana; Kesselmeier, Miriam; Winning, Johannes; Gastmeier, Petra; Brunkhorst, Frank M; Scherag, André; Pletz, Mathias W

    2015-08-01

    OBJECTIVE To quantify the Hawthorne effect of hand hygiene performance among healthcare workers using direct observation. DESIGN Prospective observational study. SETTING Intensive care unit, university hospital. METHODS Direct observation of hand hygiene compliance over 48 audits of 2 hours each. Simultaneously, hand hygiene events (HHEs) were recorded using electronic alcohol-based handrub dispensers. Directly observed and electronically recorded HHEs during the 2 hours of direct observation were compared using Spearman correlations and Bland-Altman plots. To quantify the Hawthorne effect, we compared the number of electronically recorded HHEs during the direct observation periods with the re-scaled electronically recorded HHEs in the 6 remaining hours of the 8-hour working shift. RESULTS A total of 3,978 opportunities for hand hygiene were observed during the 96 hours of direct observation. Hand hygiene compliance was 51% (95% CI, 49%-53%). There was a strong positive correlation between directly observed compliance and electronically recorded HHEs (?=0.68 [95% CI, 0.49-0.81], P<.0001). In the 384 hours under surveillance, 4,180 HHEs were recorded by the electronic dispensers. Of those, 2,029 HHEs were recorded during the 96 hours in which direct observation was also performed, and 2,151 HHEs were performed in the remaining 288 hours of the same working shift that were not under direct observation. Healthcare workers performed 8 HHEs per hour when not under observation compared with 21 HHEs per hour during observation. CONCLUSIONS Directly and electronically observed HHEs were in agreement. We observed a marked influence of the Hawthorne effect on hand hygiene performance. Infect Control Hosp Epidemiol 2015;36(8):957-962. PMID:25903555

  18. Changes in Paratethyan marine molluscs at the Early/Middle Miocene transition: diversity, palaeo-

    E-print Network

    Zuschin, Martin

    Changes in Paratethyan marine molluscs at the Early/Middle Miocene transition: diversity, palaeo/Middle Miocene transition: diversity, palaeogeography and palaeoclimate. Acta Geologica Polonica, 53 (4), 323-339. Warszawa. The transition from the Early Miocene to the Middle Miocene is a crucial point

  19. Testing Miocene Remagnetization of Bey Dalari: Timing and Amount of Neogene Rotations in SW Turkey

    E-print Network

    Utrecht, Universiteit

    Testing Miocene Remagnetization of Bey Dalari: Timing and Amount of Neogene Rotations in SW Turkey carbonates and lower Miocene flysch deposits. In this model the rotation has to postdate a Miocene of the Aegean orocline. To test this model a detailed palaeomagnetic study was conducted on lower Miocene strata

  20. Marine mammals from the Miocene of Panama Mark D. Uhen a,*, Anthony G. Coates b

    E-print Network

    Bermingham, Eldredge

    Marine mammals from the Miocene of Panama Mark D. Uhen a,*, Anthony G. Coates b , Carlos A Neogene Miocene Pliocene Cetacea Sirenia a b s t r a c t Panama has produced an abundance of Neogene vertebra from the late Miocene Tobabe Formation, a partial cetacean rib from the late Miocene Gatun

  1. FORAMINIFERA USED IN THE CONSTRUCTION OF MIOCENE POLYCHAETE WORM TUBES, MONTEREY FORMATION, CALIFORNIA, USA

    E-print Network

    Finger, Kenneth L.

    FORAMINIFERA USED IN THE CONSTRUCTION OF MIOCENE POLYCHAETE WORM TUBES, MONTEREY FORMATION concentrations of foraminiferal tests interpreted to be the remnants of worm tubes occur in the Miocene Monterey firmly establish their ages as late middle Miocene near Carmel and early late Miocene at Mission Viejo

  2. An Early Miocene anthropoid skull from the Chilean Andes.

    PubMed

    Flynn, J J; Wyss, A R; Charrier, R; Swisher, C C

    1995-02-16

    Partly because of their poor fossil record, the relationships of neotropical platyrrhine monkeys to other groups of primates and to each other remain perhaps the most poorly known for any major primate clade. Here we report the discovery of a complete platyrrhine skull from the Andes of central Chile, by far the best preserved Tertiary primate cranium from South America. This find, coupled with recent phylogenetic analyses of higher groups of anthropoid primates, has the potential to revise substantially our understanding of platyrrhine interrelationships, indicating, among other points, significant modification to reconstruction of the ancestral platyrrhine morphotype and a likely African origin for New World monkeys. A 40Ar/39Ar radioisotopic date directly associated with the skull indicates an Early Miocene age, marking the first report of South American mammals of this age from outside Argentine Patagonia. Finally, this discovery demonstrates the enormous potential of vastly distributed, but virtually untapped, Andean volcaniclastic deposits to yield further insights into the origin and diversification of South American primates. PMID:7854415

  3. Miocene vertebrates and North Florida shorelines

    USGS Publications Warehouse

    Olsen, S.J.

    1968-01-01

    Vertebrate fossils from ten localities, spread across northern Florida, give evidence of shorelines and deltas that have previously been established on geologic evidence or invertebrates alone. Terrestrial mammal remains, in association with shallow-water forms, indicate a deltaic assemblage and in several instances specific animals suggest restricted water depths at the time of sediment deposition. Fortunately diagnostic fragments of Miocene horses, Merychippus and Parahippus, are present in these beds, allowing for a rather close age evaluation of these sediments. Adequate fossil material has been collected from these localities to suggest the past environment and ecological conditions for the forms represented. By utilizing a suggested course of experiments with stream table apparatus it is possible to use the orientation of the fossil vertebrate remains as aids in determining past conditions of sediment accumulation. ?? 1968.

  4. Miocene dextral shearing between Himalaya and Tibet

    NASA Astrophysics Data System (ADS)

    Pécher, Arnaud; Bouchez, Jean-Luc; Le Fort, Patrick

    1991-07-01

    The Main Central thrust zone is the major structural feature of the Himalayas. It was active during Miocene time and accommodated at least 100 km, and possibly as much as 300 km, of convergence between India and Tibet. We present evidence that late in the tectonic history, another large shear zone, located north of the High Himalayas (the North Himalayan shear zone), underwent a phase of dextral strike-slip motion. The most plausible explanation for this phase of motion is that it reflects the onset of extension in Tibet. It is usually thought that extension began about 2.5 Ma. The phase of dextral shear we report occurred between 25 and 15 Ma. If our explanation for this movement is correct, it places the onset of extension at least 12 m.y. earlier than previously thought.

  5. Early Miocene hippopotamids (Cetartiodactyla) constrain the phylogenetic and spatiotemporal settings of hippopotamid origin

    PubMed Central

    Orliac, Maeva; Boisserie, Jean-Renaud; MacLatchy, Laura; Lihoreau, Fabrice

    2010-01-01

    The affinities of the Hippopotamidae are at the core of the phylogeny of Cetartiodactyla (even-toed mammals: cetaceans, ruminants, camels, suoids, and hippos). Molecular phylogenies support Cetacea as sister group of the Hippopotamidae, implying a long ghost lineage between the earliest cetaceans (?53 Ma) and the earliest hippopotamids (?16 Ma). Morphological studies have proposed two different sister taxa for hippopotamids: suoids (notably palaeochoerids) or anthracotheriids. Evaluating these phylogenetic hypotheses requires substantiating the poorly known early history of the Hippopotamidae. Here, we undertake an original morphological phylogenetic analysis including several “suiform” families and previously unexamined early Miocene taxa to test previous conflicting hypotheses. According to our results, Morotochoerus ugandensis and Kulutherium rusingensis, until now regarded as the sole African palaeochoerid and the sole African bunodont anthracotheriid, respectively, are unambiguously included within the Hippopotamidae. They are the earliest known hippopotamids and set the family fossil record back to the early Miocene (?21 Ma). The analysis reveals that hippopotamids displayed an unsuspected taxonomic and body size diversity and remained restricted to Africa during most of their history, until the latest Miocene. Our results also confirm the deep nesting of Hippopotamidae within the paraphyletic Anthracotheriidae; this finding allows us to reconstruct the sequence of dental innovations that links advanced selenodont anthracotheriids to hippopotamids, previously a source of major disagreements on hippopotamid origins. The analysis demonstrates a close relationship between Eocene choeropotamids and anthracotheriids, a relationship that potentially fills the evolutionary gap between earliest hippopotamids and cetaceans implied by molecular analyses. PMID:20547829

  6. Chaungtha, a new Middle Miocene mammal locality from the Irrawaddy Formation, Myanmar

    NASA Astrophysics Data System (ADS)

    Chavasseau, Olivier; Chaimanee, Yaowalak; Tun, Soe Thura; Soe, Aung Naing; Barry, John C.; Marandat, Bernard; Sudre, Jean; Marivaux, Laurent; Ducrocq, Stéphane; Jaeger, Jean-Jacques

    2006-12-01

    We describe here a mammalian assemblage originating from the locality of Chaungtha (Irrawaddy Formation, Myanmar). It represents one of the rare descriptions of a precisely located, in space, vertical section and time, fossil mammal fauna from the Irrawaddy Formation. Classically the fossil record of Irrawaddy Formation is essentially known from isolated fossils of imprecise or unknown provenance, especially concerning the stratigraphic position of the fossils along several hundred meter thick sections. The Chaungtha faunal association consists of the rhino Brachypotherium fatehjangense, the pig Conohyus thailandicus, the ruminants cf. Siamotragulus sanyathanai, cf. Siamotragulus sp. and a gomphotheriid proboscidean. This assemblage indicates that the locality is Miocene in age, and not Late Eocene as previously claimed, and roughly contemporaneous with the Chinji Formation of India-Pakistan (ca. 14-11 Ma) and with the Mae Moh Group of northern Thailand. The Chaungtha fauna, even if it displays regional characteristics, shows a strong resemblance to those of the Middle Miocene of India-Pakistan and of Thailand and reinforces the idea that South-East Asia and Pakistan were part of the same biogeographical province during the Middle Miocene.

  7. Fossil Woodwardia virginica Foliage From the Middle Miocene Yakima Canyon

    NSDL National Science Digital Library

    Kathleen B. Pigg (Arizona State University; Department of Plant Biology ADR; POSTAL)

    2004-03-09

    Fossil Woodwardia virginica foliage from the middle Miocene Yakima Canyon flora of central Washington State, USA. Vegetative and fertile features of this fossil are remarkably similar to those of the modern ""Virginia chain fern"" of the Atlantic coastal region, USA.

  8. Geomagnetic Reversals and Crustal Spreading Rates During the Miocene

    Microsoft Academic Search

    Richard J. Blakely

    1974-01-01

    Statistical analysis of the geomagnetic time scale suggests that the rate of reversals was anomalously low during the Miocene. To determine whether undetected reversals actually occurred in the Miocene, 14 magnetic profiles from a survey of the northeast Pacific by NOAA are analyzed by signal-averaging techniques. The data suggest that during the time period 7.3 to 22.7 m.y., eight short-wavelength

  9. Orbitally paced climate change across the middle Miocene climate transition

    Microsoft Academic Search

    A. E. Shevenell; J. P. Kennett

    2004-01-01

    Spectral analyses of an orbitally-tuned 3-my-long geochemical record of Miocene (16.5-13.5 Ma) climate and carbon cycling from the South Tasman Rise, Southern Ocean (paleolatitude: ˜55° S) provide insight into the processes and feedbacks involved in the middle Miocene climate transition (MMCT; 14.2-13.8 Ma), one of the three major steps in Earth's Cenozoic climate evolution. Spectral power in benthic foraminifer (Cibicidoides

  10. Tropical sea surface temperature variability near the Oligocene - Miocene boundary

    Microsoft Academic Search

    Y. Zhang; M. Pagani

    2010-01-01

    The Oligocene\\/Miocene (O-M) boundary is characterized by a period of rapid and intense glaciation labeled Mi-1 at ~ 23.1 Ma. An abrupt 1.50\\/00 increase in the benthic foraminifera oxygen isotope composition that characterizes Mi-1 may indicate a (1) significant deep-water temperature decrease; (2) major ice-sheet expansion, or the combination of both. Current coarse Mg\\/Ca-based temperature estimations for the early Miocene

  11. Diagenesis in upper Miocene sandstones, Louisiana Gulf Coast

    Microsoft Academic Search

    Gold

    1985-01-01

    Study of diagenesis in upper Miocene sandstones of coastal Louisiana documents depth-related cementation and geochemical changes of primary detrital mineralogy. Samples were collected from depths of 8000-20,000 ft (2600-6500 m) in an area roughly corresponding to the upper Miocene depocenter in the Terrebonne trough of southeast Louisiana. Sandstones are primarily subarkoses and sublitharenites with minor amounts of feldspathic litharenites and

  12. Vegetation and climate dynamics during the early Middle Miocene from Lake Sinj (Dinaride Lake System, SE Croatia)

    E-print Network

    Jiménez-Moreno, Gonzalo

    Vegetation and climate dynamics during the early Middle Miocene from Lake Sinj (Dinaride Lake 2008 Keywords: pollen vegetation climate change Miocene Croatia Pollen data from sediments from in vegetation during the early Middle Miocene. Good correspondence between the palaeo

  13. Late Miocene paleoenvironmental changes in North Africa and the Mediterranean recorded by geochemical proxies (Monte Gibliscemi section, Sicily)

    E-print Network

    Utrecht, Universiteit

    Late Miocene paleoenvironmental changes in North Africa and the Mediterranean recorded: Geochemical proxy parameters Palaeoclimate Eastern Mediterranean Late Miocene Biosiliceous production Miocene palaeoenvironmental conditions (~9.7­7.0 Ma) in North Africa. Here we have utilised carbonate

  14. Influence of early Miocene tectonism on Miocene deposystems, Tejon area, Kern County, California

    SciTech Connect

    Hirst, B.M.

    1986-04-01

    The Tejor area, located in the southeastern end of the San Joaquin Valley of California, provides an excellent opportunity to study earliest Miocene tectonics and their subsequent control on Miocene deposystems in the east slope setting. Abundant outcrop and subsurface control, correlative time markers (including volcanic units and micropaleontologic reports), and a relatively mild overprinting by recent structuring facilitated this 3-year study. Late Zemorrian through early Saucesian (22 Ma) volcanic flows and eruptives covered the area while coincident tensional faulting caused the Zemorrian-age Vedder shelf-slope system to collapse. A horst-and-graben basin system resulted, with a narrow serrated shelf along the eastern margin. Onset of Saucesian deposition was dominated by conglomeratic turbidites spilling into silled basin depocenters. The clastic load included typical Sierran-derived material and volcanic detritus from the prior flows. Rugged sea floor relief controlled channel courses and sediment thickness. Turbidite deposition continued through the earliest Mohnian. The early Saucesian sea flow topography exerted progressively less effect on channel courses, while influence from previous channel buildups increased. Clastic sorting improved with time as the shelf matured and the slope gradient decreased, and clean reservoir channel sands were deposited in meanderlike patterns. This sequence of events is critical to working the structural and stratigraphic hydrocarbon potential of the Tejon area. Zemorrian Vedder and Eocene-age production is associated with paleohorst blocks (e.g., Tejon North oil field and Tunis Creek pool of the Tejon Hills oil field).

  15. Criteria for successful exploration for Miocene reef production in the Philippines

    SciTech Connect

    Downey, M.W. (Roxanna Oil Co., Katy, TX (USA))

    1990-06-01

    An abundance of modern geologic, geophysical, and geochemical data has been provided to interested members of the petroleum industry by the Philippine government, in cooperation with the World Bank. These data have been analyzed to assess whether more, and larger, Miocene reef fields should be expected in the Philippines. In the past decade, exploration by Cities Service (OXY), Amoco, Alcorn, and others has resulted in the discovery of several small Miocene reef and Miocene sandstone oil fields in offshore Palawan. Phillips/Shell also made a significant gas discovery of about 750 bcf in a Palawan Miocene reef that is currently uneconomic to develop given the water depth (1,090 ft) and distance from users. Miocene reefs are commonly buried within Miocene clastics, and, where these impinging clastics are porous, they allow pathways for hydrocarbons to leak from the Miocene reefs. Drape closure is an important positive factor in assessing seal risk for Philippine Miocene reefs. Source rocks to charge middle and upper Miocene reefs are typically restricted to lower Miocene horizons. Geothermal gradients are modest in much of the Philippine offshore, and only select areas provide sufficient burial to mature and expel significant hydrocarbons. It is predicted by the author that additional, larger, and highly profitable Miocene reef fields will be found by future explorers in areas where Miocene reefs have drape closure top seals and are adjacent to deeply buried Miocene source rocks.

  16. Isolation and identification of flavonoids, including flavone rotamers, from the herbal drug 'Crataegi folium cum flore' (hawthorn).

    PubMed

    Rayyan, S; Fossen, T; Solheim Nateland, H; Andersen, O M

    2005-01-01

    Twelve flavonoids, including seven flavones, four flavonols and one flavanone, were isolated from methanolic extract of the herbal drug 'Crataegi folium cum flore' (hawthorn leaves and flowers) by a combination of CC (over Amberlite XAD-7 and Sephadex LH-20) and preparative HPLC. Their structures, including that of the novel flavonol 8-methoxykaempferol 3-O-(6"-malonyl-beta-glucopyranoside), were elucidated by homo- and heteronuclear NMR and electrospray/MS. The 1H- and 13C-NMR of all compounds, including rotameric pairs of five flavone C-glycosides, were assigned. The presence and relative proportion of each rotamer was shown by various NMR experiments, including two-dimensional nuclear Overhauser and exchange spectroscopy, to depend on solvent, linkage position and structure of the C-glycosyl substituent. PMID:16223090

  17. Quantification of the Hawthorne effect in hand hygiene compliance monitoring using an electronic monitoring system: a retrospective cohort study

    PubMed Central

    Srigley, Jocelyn A; Furness, Colin D; Baker, G Ross; Gardam, Michael

    2014-01-01

    Background The Hawthorne effect, or behaviour change due to awareness of being observed, is assumed to inflate hand hygiene compliance rates as measured by direct observation but there are limited data to support this. Objective To determine whether the presence of hand hygiene auditors was associated with an increase in hand hygiene events as measured by a real-time location system (RTLS). Methods The RTLS recorded all uses of alcohol-based hand rub and soap for 8?months in two units in an academic acute care hospital. The RTLS also tracked the movement of hospital hand hygiene auditors. Rates of hand hygiene events per dispenser per hour as measured by the RTLS were compared for dispensers within sight of auditors and those not exposed to auditors. Results The hand hygiene event rate in dispensers visible to auditors (3.75/dispenser/h) was significantly higher than in dispensers not visible to the auditors at the same time (1.48; p=0.001) and in the same dispensers during the week prior (1.07; p<0.001). The rate increased significantly when auditors were present compared with 1–5?min prior to the auditors’ arrival (1.50; p=0.009). There were no significant changes inside patient rooms. Conclusions Hand hygiene event rates were approximately threefold higher in hallways within eyesight of an auditor compared with when no auditor was visible and the increase occurred after the auditors’ arrival. This is consistent with the existence of a Hawthorne effect localised to areas where the auditor is visible and calls into question the accuracy of publicly reported hospital hand hygiene compliance rates. PMID:25002555

  18. Miocene sequence biostratigraphy of the northern Gulf of Mexico

    SciTech Connect

    Jiang, M.M. (ARCO Oil and Gas Company, Houston, TX (United States))

    1993-09-01

    The Miocene floral pulse model of Jiang and Watkins is revised. The new revision suggests that the Gulf of Mexico Miocene floral pulses, corresponding to the traditional foraminiferal tops, are transgression surfaces of the fourth-order sequences. These pulses show diverse magnitudes and when they are plotted on a depth (or time) tract, their relative magnitudes show an orderly wavy pattern comparable to the Haq et al.'s third-order cycles in the Miocene. After iterative comparison, the condensed intervals of these Miocene third-order sequences have been determined as, in descending order, Cyclammina 3, the second Cibicides carstensi, the second Textularia W, Cristellaria I, Robulus 43, Discorbis B, the third Marginulina A, and Textularia panamensis (= fauna unit II). The least prominent pulses suggesting the third-order cycle highstands (or shelf-margin wedges) are suggested as, in descending order, Textularia X, Bolivina thalmanni, Globorotalia fohsi robusta, Bigenerina humblei, Cibicides opima, Saracenaria schencki, Marginulina A (= second Robulus chambersi), and Siphonina davisi. Redeposited Cretaceous nanno species are an important component in the Gulf of Mexico middle and lower Miocene. Significant concentrations of these species are found primarily in the third-order cycle highstands, one exception being the Marginulina A third-order cycle highstand that in the High Island and West Cameron areas contained only rare redeposited Cretaceous nannos.

  19. A molecular organic carbon isotope record of miocene climate changes

    SciTech Connect

    Schoell, M. (Chevron Petroleum Technology Co., La Habra, CA (United States)); Schouten, S.; Sinninghe Damste', J.S.; Leeuw, J.W. de (Netherlands Institute of Sea Research, Texel (Netherlands)); Summons, R.E. (Australian Geological Survey Organization, Canberra (Australia))

    1994-02-25

    The difference in carbon-13 ([sup 13]C) contents of hopane and sterane biomarkers in the Monterey formation (Naples Beach, California) parallels the Miocene inorganic record of the change in [sup 18]O ([delta][sup 18]O), reflecting the Miocene evolution from a well-mixed to a highly stratified photic zone (upper 100 meters) in the Pacific. Steranes ([delta][sup 13]C = 25.4 [+-] 0.7 per mil versus the Pee Dee belemnite standard) from shallow photic-zone organisms do not change isotopically throughout the Miocene. In contrast, sulfur-bound C[sub 35] hopanes (likely derived from bacterial plankton living at the base of the photic zone) have systematically decreasing [sup 13]C concentrations in Middle and Late Miocene samples ([delta][sup 13]C = 29.5 to [minus]31.5 per mil), consistent with the Middle Miocene formation of a carbon dioxide-rich cold water mass at the base of the photic zone.

  20. First record of Mylagaulid rodents (Rodentia, Mammalia) from the Miocene of Eastern Siberia (Olkhon Island, Baikal Lake, Irkutsk Region, Russia).

    PubMed

    Tesakov, A S; Lopatin, A V

    2015-01-01

    A new genus and species of rodent, Lamugaulus olkhonensis, belonging to the subfamily Promylagaulinae of the family Mylagaulidae, is described on the basis of isolated teeth from the Khalagay Formation of the Lower Miocene Tagay locality (Olkhon island, Lake Baikal, Irkutsk Region). This is the first record of mylagaulids in Eastern Siberia, significantly expanding the data on the distribution of this mainly North American group of rodents in Asia and showing its presence outside the Central Asian arid zone. PMID:25773245

  1. Miocene shallow-water carbonates on the Eratosthenes Seamount, easternmost Mediterranean Sea 

    E-print Network

    Robertson, Alastair H F

    1998-01-01

    Miocene shallow-water limestones of the Eratosthenes Seamount add considerably to the picture of widespread and heterogeneous Mediterranean Miocene reef development. Shallow-water limestones were cored at two sites on the ...

  2. Middle Miocene closure of the Central American Seaway

    NASA Astrophysics Data System (ADS)

    Montes, C.; Cardona, A.; Jaramillo, C.; Pardo, A.; Silva, J. C.; Valencia, V.; Ayala, C.; Pérez-Angel, L. C.; Rodriguez-Parra, L. A.; Ramirez, V.; Niño, H.

    2015-04-01

    Uranium-lead geochronology in detrital zircons and provenance analyses in eight boreholes and two surface stratigraphic sections in the northern Andes provide insight into the time of closure of the Central American Seaway. The timing of this closure has been correlated with Plio-Pleistocene global oceanographic, atmospheric, and biotic events. We found that a uniquely Panamanian Eocene detrital zircon fingerprint is pronounced in middle Miocene fluvial and shallow marine strata cropping out in the northern Andes but is absent in underlying lower Miocene and Oligocene strata. We contend that this fingerprint demonstrates a fluvial connection, and therefore the absence of an intervening seaway, between the Panama arc and South America in middle Miocene times; the Central American Seaway had vanished by that time.

  3. Miocene isotope chronostratigraphy: North-central Gulf of Mexico

    SciTech Connect

    Trainor, D.M.; Williams, D.F. (Univ. of South Carolina, Columbia (United States))

    1991-03-01

    Isotope chronostratigraphy has proven extremely useful in providing high resolution stratigraphic correlations and detailed information relating to the complex nature of sediment accumulation rates in Plio-Pleistocene exploration wells of the north-central Gulf of Mexico (GOM). Current research on the isotopic composition of foraminifera recovered from Miocene age sediments in the north-central GOM indicate that the glacio-eustatic cycles documented in the Plio-Pleistocene are found to continue into the late Miocene. During the middle Miocene ample isotopic signals (3 per mil) exist to provide a high resolution stratigraphy. {delta}{sup 18}O data from the planktonic foraminifera Orbulina universa from Eureka core 66-73 in the Desoto Canyon form a relatively complete record from approximately 8.5-16 Ma. The record displays a greater than 3 per mil range in {delta}{sup 18}O values through the middle Miocene. This Miocene {delta}{sup 18}O record from E66-73 is compared to exploration wells from the following areas: Mississippi Canyon, central GOM, East Breaks, South Galveston, and the Green Canyon. In the downdip, deeper water sections, the primary water column signal appears to be well preserved through the middle Miocene. When working updip in shallower water depths, there appears to be some diagenetic zones displaying extremely negative {delta}{sup 18}O values ({gt}-6 per mil) that could be related to fluid migration events or possibly related to sand occurrence. Also found in these updip wells is a zone of consistent diagenetic overprint in the lower section of the well. In this interval, the base line for the {delta}{sup 18}O values is shifted by as much as 3-4 per mil in the negative direction.

  4. Early, middle, and late Miocene basin development, California

    SciTech Connect

    Bachman, S.B.

    1988-03-01

    Contrary to earlier models of progressive basin development related to northward migration of the Mendocino triple junction, it can now be documented that the major basins of coastal California developed at about the same time in the late Oligocene to early Miocene. This basin development is marked by rapid deepening of basin floors, subsequent changes in depositional facies from nonmarine and shallow marine to deep marine, and widespread volcanism dated at 23-20 Ma. The coastal basins likely formed by rifting and subsidence linked to the proximity of the Farallon-pacific spreading ridge and the subduction of hot young oceanic crust, but cannot be correlated to any existing models of triple junction migration. Indeed, strike-slip restored positions of the coastal basins at their inception indicate that the basins were spread out over about 800 km of the southern coast of California. The Miocene basins were likely larger than the present coastal basins, although their configurations are obscured by late Neogene faulting and erosion. It is likely, however, that paleohighs separated at least some of the margin into proximal and distal basins. With local exceptions, structuring in the Miocene basins was primarily extensional, with widespread strike-slip and thrust tectonics restricted mainly to latest Miocene and younger events. Plate reconstructions suggest several hundred kilometers of transform motion occurred along the California margin during the Miocene, but there is only limited evidence of this movement in the known history of either the basins or the major faults of California. Sedimentation during the Miocene was controlled by both oceanic conditions (biogenic component) and the relative abundance of clastic input. The clastic input was controlled by a combination of proximal vs distal basinal positions, eustatic sea level changes, and local tectonics.

  5. Miocene connectivity between the Central and Eastern Paratethys: Constraints from the western Dacian Basin

    E-print Network

    Utrecht, Universiteit

    Miocene connectivity between the Central and Eastern Paratethys: Constraints from the western and lakes. This study presents constraints on Miocene sea and lake level fluctuations in the Dacian Basin fluctuations in the western part of the Dacian Basin during the Middle Miocene were primarily driven

  6. Miocene deep-water agglutinated foraminifera from ODP Hole 909c: Implications for the paleoceanography

    E-print Network

    Kaminski, Michael A.

    Miocene deep-water agglutinated foraminifera from ODP Hole 909c: Implications.kender@ucl.ac.uk ABSTRACT: Deep-water agglutinated Foraminifera (DWAF) are investigated from Miocene sediments recovered far into the Miocene at this local- ity, confirming the hypothesis that the Arctic and northern

  7. Understanding the Middle Miocene Climatic Optimum: Evaluation of Deuterium Values (D) Related to

    E-print Network

    Blais, Brian

    Understanding the Middle Miocene Climatic Optimum: Evaluation of DeuteriumEicance · The Middle Miocene ClimaFc OpFmum · A geologic Fme period, 15-17 million years ago;#12;SigniEicance · The Middle Miocene ClimaFc OpFmum · A geologic Fme period, 15

  8. Middle Miocene extension in the Gulf Extensional Province, Baja California: Evidence from the southern Sierra Juarez

    E-print Network

    Lee, Jeff

    Middle Miocene extension in the Gulf Extensional Province, Baja California: Evidence from, structural stud- ies, and geochronology of Miocene volcanic and sedimentary rocks in the southern Si- erra­middle Miocene rocks including fluvial strata, in- termediate composition volcanic deposits, basalt lava flows

  9. High-resolution palynological analysis in late earlymiddle Miocene core from the Pannonian Basin, Hungary

    E-print Network

    Jiménez-Moreno, Gonzalo

    High-resolution palynological analysis in late early­middle Miocene core from the Pannonian Basin-resolution palynological analysis in the Karpatian­Sarmatian (late early­middle Miocene) interval of the borehole Tengelic in a subtropical­warm temperate humid climate, reflecting the so-called Miocene climatic optimum. Pollen changes

  10. RONGEURS DU MIOCENE SUPERIEUR DE CHORORA, ETHIOPIE: MURINAE, DENDROMURINAE ET CONCLUSIONS

    E-print Network

    Paris-Sud XI, Université de

    RONGEURS DU MIOCENE SUPERIEUR DE CHORORA, ETHIOPIE: MURINAE, DENDROMURINAE ET CONCLUSIONS par Denis, Muridae Key-words: Late Miocene, Ethiopia, Rodentia, Muridae UPR 2147 CNRS - 44 rue de l'Amiral Mouchez of the Late Miocene. INTRODUCTION Le site de Chorora, dans la localité-type de la formation du même nom, a d

  11. An astronomical polarity timescale for the late middle Miocene based on cyclic continental sequences

    E-print Network

    Utrecht, Universiteit

    An astronomical polarity timescale for the late middle Miocene based on cyclic continental an astronomically tuned polarity timescale for the late middle Miocene based on a cyclic shallow lacustrine, cyclostratigraphy, astronomical timescale, orbital forcing, Miocene Citation: Abdul Aziz, H., W. Krijgsman, F. J

  12. Mitochondrial relationships and divergence dates of the African colobines: evidence of Miocene origins

    E-print Network

    Oregon, University of

    Mitochondrial relationships and divergence dates of the African colobines: evidence of Miocene another by the end of the Miocene, and that by the Plio-Pleistocene many of the species lineages were is found in deposits dating to the late Miocene (9e8.5 Ma; Kingston et al., 2002). Colobines

  13. Rhinocerotidae from the Middle Miocene Hominoid Locality of andir (Turkey). 1 figure, 2 plates

    E-print Network

    Boyer, Edmond

    1 Rhinocerotidae from the Middle Miocene Hominoid Locality of Çandir (Turkey). 1 figure, 2 plates Miocene localities. More specimens of the 3 species identified by HEISSIG (1976), Beliajevina grimmi. Key-words: Middle Miocene, Turkey, Mammalia, Perissodactyla, Rhinocerotidae Introduction In 1976, K

  14. New specimens of Propotamochoerus (Suidae, Mammalia) from the late Miocene of the Balkans

    E-print Network

    Boyer, Edmond

    New specimens of Propotamochoerus (Suidae, Mammalia) from the late Miocene of the Balkans Denis;Abstract: We describe new remains of the small Suidae Propotamochoerus from the late Miocene of Macedonia, probably distinct from the P. palaeochoerus - P. provincialis lineage. Key words: late Miocene, Turolian

  15. Astronomic calibration of the late Oligocene through early Miocene geomagnetic polarity time scale

    E-print Network

    Zachos, James

    Astronomic calibration of the late Oligocene through early Miocene geomagnetic polarity time scale) span the late Oligocene through early Miocene ( f24­16 Ma) at a temporal resolution of f5 ky. Over. In an initial age model, we use the newly derived age of the Oligocene/Miocene (O/M) boundary of 23.0 Ma

  16. The Purisima Formation is an important upper Miocene and Pliocene stratigraphic unit in central California, cropping

    E-print Network

    Laughlin, Robert B.

    Abstract The Purisima Formation is an important upper Miocene and Pliocene stratigraphic unit- sima Formation record a latest Miocene transgressive event, whereas the middle and upper parts that the Purisima Formation ranges in age from the latest Miocene (about 7 Ma) to the late Pliocene (about 2.6 Ma

  17. Ruminants, other than Giraffidae from the middle Miocene hominoid locality of andir 9 figures, 3 plates

    E-print Network

    Paris-Sud XI, Université de

    1 Ruminants, other than Giraffidae from the middle Miocene hominoid locality of Çandir (Turkey). 9 especially open. Key-words.- Middle Miocene, Turkey, Mammalia, Artiodactyla, Ruminantia Introduction The middle Miocene site of Çandir, 60 km N-E of Ankara, has long been known for having yielded the hominoid

  18. NEW CHALICOTHERIIDAE (PERISSODACTYLA, MAMMALIA) FROM THE LATE MIOCENE OF DENIS GERAADS

    E-print Network

    Paris-Sud XI, Université de

    1 NEW CHALICOTHERIIDAE (PERISSODACTYLA, MAMMALIA) FROM THE LATE MIOCENE OF BULGARIA DENIS GERAADS 1 Miocene of Europe, increasing the diversity of the family, and providing the first definite evidence, to revive Anisodon Lartet for middle Miocene forms, and to suggest the extension of Kalimantsia

  19. American Journal of Botany 84(8): 981991. 1997. FOSSIL MUSHROOMS FROM MIOCENE AND CRETACEOUS

    E-print Network

    Hibbett, David S.

    981 American Journal of Botany 84(8): 981­991. 1997. FOSSIL MUSHROOMS FROM MIOCENE AND CRETACEOUS Cretaceous and Miocene ambers. Archaeomarasmius leggetti gen. et sp. nov., from mid-Cretaceous amber of New is represented by a single complete fruiting body from Miocene amber of the Dominican Republic, is similar

  20. Discordant paleomagnetic direction in Miocene rocks from the central Tarim Basin: evidence for local deformation and

    E-print Network

    Utrecht, Universiteit

    Discordant paleomagnetic direction in Miocene rocks from the central Tarim Basin: evidence paleomagnetic sites were collected from red mudstones and sandstones of the Miocene Wuqia Formation. Thermal: inclination (I) = 29.4; declination (D) = 24.7; K95 = 6.2. When compared to the Miocene expected direction (at

  1. C4 expansion in the central Inner Mongolia during the latest Miocene and early Pliocene

    E-print Network

    Wang, Yang

    C4 expansion in the central Inner Mongolia during the latest Miocene and early Pliocene Chunfu Miocene The emergence of C4 photosynthesis in plants as a significant component of terrestrial ecosystems grasses in the latest Miocene and Pliocene has been widely documented around the world, the spatial

  2. Miocene-Pliocene bathyal benthicforaminifera and the uplift ofBuff Bay, Jamaica

    E-print Network

    Miocene-Pliocene bathyal benthicforaminifera and the uplift ofBuff Bay, Jamaica Miriam E. Katz Miocene to Pliocene sections exposed in readouts east of Buff Bay, Jamaica, for quantitative benthicMember of the Montpelier Formation and the Buff Bay Formation (middle to upper Miocene) were depositeda

  3. Anchitherium from the middle Miocene hominoid locality of andir (Turkey). Erksin GLE * & Denis GERAADS **

    E-print Network

    Paris-Sud XI, Université de

    1 Anchitherium from the middle Miocene hominoid locality of Çandir (Turkey). 1 plate Erksin GÜLEÇ is lacking at Çandir. Thus, although the few morphological differences with other Turkish Middle Miocene populations are of unknown polarity, this suggests that Çandir is earlier than the late Middle Miocene. Key

  4. Effects of Oligo-Miocene global climate changes on mammalian species richness in the northwestern

    E-print Network

    California at Berkeley, University of

    Effects of Oligo-Miocene global climate changes on mammalian species richness in the northwestern million years old (late Oligocene through late Miocene) for three geographic regions in the USA between all three biogeographic provinces. This peak coincides with the Mid-Miocene Climatic Optimum

  5. Chalicotheriidae from the middle Miocene hominoid locality of andir (Turkey). Denis GERAADS * & Gerek SARA **

    E-print Network

    Boyer, Edmond

    1 Chalicotheriidae from the middle Miocene hominoid locality of Çandir (Turkey). Denis GERAADS significance of the differences. Key-words.- Middle Miocene, Turkey, Mammalia, Perissodactyla, Chalicotheriidae hoofs, are represented in the Middle Miocene of Europe and Asia by their two subfamilies

  6. Journal of Geodynamics Offshore Oligo-Miocene volcanic fields within the Corsica-Liguria Basin

    E-print Network

    Paris-Sud XI, Université de

    1 Journal of Geodynamics Offshore Oligo-Miocene volcanic fields within the Corsica-Liguria Basin-rich calc-alkaline. Miocene volcanic activity was important in Sardinia, where andesites and ignimbrites to our initial project. Key-Words: Mediterranean, Ligurian margins and Basin, Offshore Corsica, Miocene

  7. Modelling the Miocene climatic optimum, Part 1: land and atmosphere1 Herold, N.1*

    E-print Network

    Müller, Dietmar

    1 Modelling the Miocene climatic optimum, Part 1: land and atmosphere1 Herold, N.1* , Huber, M.2 to middle Miocene (~20 ­ 14 Ma) vegetation, topography, bathymetry and modern13 CO2. A decrease and topography were responsible for Miocene warmth in the high latitude northern20 hemisphere while a combination

  8. Proboscidea from the middle Miocene hominoid site of andir (Turkey) 1 figure, 1 plate

    E-print Network

    Paris-Sud XI, Université de

    1 Proboscidea from the middle Miocene hominoid site of Çandir (Turkey) 1 figure, 1 plate Denis to the Amebelodont Protanancus. Key-words.- middle Miocene, Turkey, Mammals, Proboscidea Introduction Proboscideans of Choerolophodon, especially those from the upper Miocene, which may be almost as broad as long (figure 1

  9. Vegetation and climate in the latest Oligoceneearliest Miocene in Jylland, Denmark Linda M. Larsson a,

    E-print Network

    Vajda, Vivi

    Vegetation and climate in the latest Oligocene­earliest Miocene in Jylland, Denmark Linda M December 2009 Keywords: palaeobotany palynoflora climate change Oligocene Miocene pollen miospores Denmark Two exposures in Jylland, Denmark, encompassing beds of latest Oligocene to earliest Miocene age

  10. Rhinocerotidae (Mammalia) from the Late Miocene of Bulgaria DENIS GERAADS, Paris, and NIKOLA SPASSOV, Sofia

    E-print Network

    Paris-Sud XI, Université de

    Rhinocerotidae (Mammalia) from the Late Miocene of Bulgaria DENIS GERAADS, Paris, and NIKOLAÏ Europa. Abstract We describe the remains of Rhinocerotidae from about 10 Late Miocene localities e y - w o r d s : Rhinocerotidae, Mammalia, Late Miocene, Bulgaria, Balkans S c h l ü s s e l w ö r

  11. NEW HIPPOTRAGINI (BOVIDAE, MAMMALIA) FROM THE LATE MIOCENE OF TOROS-MENALLA (CHAD)

    E-print Network

    Boyer, Edmond

    1 NEW HIPPOTRAGINI (BOVIDAE, MAMMALIA) FROM THE LATE MIOCENE OF TOROS-MENALLA (CHAD) DENIS GERAADS.--HIPPOTRAGINI FROM THE LATE MIOCENE OF CHAD hal-00265413,version1-20Nov2009 Author manuscript, published in "Journal of the bovid tribe Hippotragini was rather poor. We describe here two new taxa from the late Miocene of Toros

  12. Sinotragus (Bovidae, Mammalia) from Turkey, and the Late Miocene Middle Asiatic Province Denis Geraads -Paris

    E-print Network

    Paris-Sud XI, Université de

    Sinotragus (Bovidae, Mammalia) from Turkey, and the Late Miocene Middle Asiatic Province Denis Geraads - Paris Erksin Güleç - Ankara and Tanju Kaya - Izmir Abstract: The Late Miocene Yataan Formation in Late Miocene times. The discovery of Sinotragus in Turkey thus confirms an idea already put forward 50

  13. Long-period orbital control on middle Miocene global cooling: Integrated stratigraphy and astronomical tuning

    E-print Network

    Utrecht, Universiteit

    Long-period orbital control on middle Miocene global cooling: Integrated stratigraphy in the middle Miocene global cooling (13.82 Ma ± 0.03) coincides with minimum eccentricity values associated Paleogene and Neogene. The stepwise character of the middle Miocene cooling event appears to be controlled

  14. Molar crown formation in the Late Miocene Asian hominoids, Sivapithecus parvada and Sivapithecus indicus

    E-print Network

    Smith, Tanya M.

    Molar crown formation in the Late Miocene Asian hominoids, Sivapithecus parvada and Sivapithecus and geographic perspective on evolutionary devel- opmental biology in Miocene hominoids. Here we report some for the protocone of S. indicus lie within the range of first molar (M1) formation times for the majority of Miocene

  15. Syn-tectonic sedimentary evolution of the Miocene atallar Basin, southwestern Turkey

    E-print Network

    Boyer, Edmond

    Syn-tectonic sedimentary evolution of the Miocene Çatallar Basin, southwestern Turkey Erdal Kosun Orléans cedex 2 France Abstract The Çatallar Basin is one of the Miocene basins located in the southern: Sedimentology; Biostratigraphy; Source of detritals; Miocene; Basin analyses; Lycian Nappes 1. Introduction

  16. Biostromal Coral Facies -A Miocene Example from the Leitha Limestone (Austria) and its

    E-print Network

    399 Biostromal Coral Facies -A Miocene Example from the Leitha Limestone (Austria) and itsLeitha Limestoneof Badenian age (Middle Miocene)at the type-localityin Grosshoeflein(Bur- genland province and taxonomic difficulties in the com- parison of badly preserved Miocene corals with Recent counterparts

  17. Giraffidae from the middle Miocene hominoid locality of andir (Turkey). 1 figure, 2 plates

    E-print Network

    Paris-Sud XI, Université de

    1 Giraffidae from the middle Miocene hominoid locality of Çandir (Turkey). 1 figure, 2 plates Denis yielded one of the best collections of Giraffidae from the Middle Miocene of the Eastern Mediterranean this area and the Siwaliks raises some interesting phylogenetic problems. Key-words.- Middle Miocene, Turkey

  18. Correlating Miocene sequences in onshore New Jersey boreholes (ODP Leg 150X) with global 18

    E-print Network

    Correlating Miocene sequences in onshore New Jersey boreholes (ODP Leg 150X) with global 18 O Miocene sequences that we dated with Sr isotopic stratigraphy. Sequence boundaries correlate with deep-level change. Maryland Miocene outcrops appear to correlate with New Jersey sequences and the 18 O record

  19. The middle Miocene hominoid site of andir, Turkey: general paleoecological conclusions from the mammalian fauna.

    E-print Network

    Paris-Sud XI, Université de

    1 The middle Miocene hominoid site of Çandir, Turkey: general paleoecological conclusions from of the paleoenvironment at the middle Miocene Çandir. The predominance of grazing large Mammals in the Griphopithecus-250" #12;2 Key-words: middle Miocene, Turkey, paleoecology, mammals Introduction The site of Çandir has

  20. RESEARCH ARTICLE Open Access Early Miocene origin and cryptic diversification of

    E-print Network

    Wake, David B.

    RESEARCH ARTICLE Open Access Early Miocene origin and cryptic diversification of South American Central America by at least the Early Miocene, ca. 23.6 MYA (95% HPD 15.9-30.3 MYA), and subsequently salamanders likely arrived at least by the Early Miocene, well before the completion of the Late Pliocene

  1. Systematic Entomology (2012), 37, 784792 Geometric morphometric analysis of a new Miocene

    E-print Network

    Rasmont, Pierre

    2012-01-01

    Systematic Entomology (2012), 37, 784­792 Geometric morphometric analysis of a new Miocene bumble: Bombini) from the Miocene Randeck Maar of southwestern Germany is described and illustrated. The specimen/middle Miocene. The Randeck Maar fossil is formally described as Bombus (Bombus) randeckensis Wappler & Engel sp

  2. Middlelate Miocene benthic foraminifera in a western equatorial Indian Ocean depth transect: Paleoceanographic implications

    E-print Network

    Royer, Dana

    Middle­late Miocene benthic foraminifera in a western equatorial Indian Ocean depth transect Miocene (17­5 Ma) benthic foraminiferal faunas (N63 m) from a depth transect in the western equatorial reserved. Keywords: Miocene; Benthic foraminifera; Indian Ocean; Paleoceanography; Monsoon; ODP 1

  3. Miocene sedimentation in the Sigsbee Abyssal Plain, Gulf of Mexico

    E-print Network

    Kuzela, Robert Christian

    1971-01-01

    ~ 10 , :0. , 3 70 3 3i c Jl 3 75 3 2 71 v. " O~ 4 5 C7 r+ 2 2-7 9 '12 ~ 4 2( 7 ? 11 12-1 7 14-3 3 51 4-ray sample 4. ) An interpretation of this depositional environment and the changes that occurred in the basin from Miocene... MIOCENE SEDIMENTATION IN THE SIGSBEE ABYSSAL PLAIN, GULF OF MEXICO A Thesis by ROBERT CHRISTIAN XUZELA Submitted to the Graduate College of Texas A&M University in pa, rtia. l ulfillment of the r quirement for the degree of MASTER...

  4. Chemical evolution of Miocene wood: Example from the Belchatow brown coal deposit, central Poland

    USGS Publications Warehouse

    Drobniak, A.; Mastalerz, Maria

    2006-01-01

    Miocene conifer wood samples from the Belchatow brown coal deposit in Poland were studied in order to discuss a range of chemical variations that occur as a result of biochemical coalification. Petrographic analysis, ultimate analysis, electron microprobe technique, and FTIR spectroscopy were used in this study. Our data show several progressive trends in functional groups distribution that take place during the wood transformation from group 1 to group 4, such as an overall increase in aromaticity, an increase in lignin/cellulose ratio, and an increase in oxygen functionalities. Other observations include an increase in aliphatic stretching and bending functionalities from groups 1 to 3; followed by a decrease in the wood of group 4; appearance of aliphatic out-of-plane bands in group 3 and increase in group 4; an increase in CH2/CH3 in group 4 compared to the other groups; and decrease in O-H groups in group 4 compared to other groups. These observations, together with other chemical and petrological observations, indicate that the progressive elimination of cellulose and modification of lignin are dominant processes of the wood transformation. ?? 2005 Elsevier B.V. All rights reserved.

  5. North American black-fruited hawthorns. I. Variation in floral construction, breeding system correlates, and their possible evolutionary significance in Crataegus sect. Douglasii London

    Microsoft Academic Search

    Timothy A. Dickinson; Svenja Belaoussoff; Rhoda M. Love; M. Muniyamma

    1996-01-01

    Differences in the numbers of stamens and styles per flower are conspicuous features of variation in North American hawthorns\\u000a (Crataegus L.). Variation in stamen number between individuals is discontinuous, with modes of approximately 20 and 10 (or fewer). In\\u000a North American black-fruited sectionDouglasii\\u000a Loudon the 10-stamen morphotype is exclusively polyploid, whereas the 20-stamen morphotype comprises both diploids and polyploids.\\u000a Polyploidy

  6. The lithostratigraphy of Miocene series from Tunisia, revisited

    NASA Astrophysics Data System (ADS)

    Mannaï-Tayech, Beya

    2009-06-01

    In the Mediterranean region, the Miocene is a rather particular tectonic, eustatic and climatic epoch. In Tunisia, the complex distribution of the sedimentary sequences has been controlled by the interaction of these factors. These sequences are composed mostly of silici-clastic packages filling usually rim-syncline, graben and half-graben basins. In the absence of a solid biostratigraphic framework, the dating and correlation of certain formations are not yet clearly perceived. In spite of the availability of some elements of dating (planktonic foraminifera, vertebrates), the solution remains as a whole unclear. The question thus remains as to the significance of the frequency and occurrence of discontinuities, and consequently of those hiatuses between Miocene Formations. Thus, in the light of the recent palynologic, sedimentological and vertebrate biostratigraphical data, a new reading of the paleogeography and paleoenvironment of the Miocene from Tunisia is essential. In this work, the results of multi-field studies supported by the compilation of the literature, enable sensible discussion of the proposed ages, analyze the depositional environments, and concomitantly support correlations between the Miocene Formations recognized to the South-East of the Eastern Dorsale of Tunisia. It is demonstrated that the Beglia and Saouaf Formations are partially equivalent rather than being superposed, as it has been previously surmised. A new, marine formation, the "Kef Ettir Formation", is also proposed.

  7. Lower Miocene sequence stratigraphy of Taishi Basin, offshore Western Taiwan

    SciTech Connect

    Ting, J.S. (Chinese Petroleum Corp., Taipei (Taiwan, Province of China)); Lee, T.Y. (National Taiwan Normal Univ., Taipei (Taiwan, Province of China))

    1994-07-01

    By applying sequence stratigraphic concepts to the lower Miocene sedimentary sections in Taishi Basin, offshore western Taiwan, it is possible to identify four third-order sequences from subsurface information. The overall depositional environment of these sequences is in a deltaic setting. Following the early Aquitanian flood (24.8 Ma), the basin experienced a long period of sea level highstand, which generated more than 400 m of highstand prograding units. In late Aquitanian time, a thick retrogradational package ([approximately]250 m) was developed in response to rising sea level. Sandy units are now the dominant sediment type in the Taishi Basin. Until the early middle Miocene (15-16 Ma), the basin was flooded and deposited with thick marine shale. This analysis shows that the lower Miocene sedimentary sequences in the Taishi Basin have a good correlation with the Haq et al. (1987) chart, which would imply a passive margin setting for the Taishi Basin in the early Miocene. The predictive nature of the sequence stratigraphic technique can help in redefining the hydrocarbon play concepts in this area.

  8. Early Miocene Carbonate Dissolution in the Eastern Equatorial Pacific 

    E-print Network

    Wilson, Julia Keegan

    2014-11-19

    , XRF records are used here to define an early Miocene low CaCO3 event in the equatorial Pacific that corresponds to the seismic horizon termed “Lavender”. The low CaCO3 interval is correlated at submeter scale in 4 drill sites from IODP Expedition 320...

  9. Lateritic bauxite in central Germany and implications for Miocene palaeoclimate

    Microsoft Academic Search

    Torsten Schwarz

    1997-01-01

    Intense chemical weathering during middle Miocene times led to the formation of deep ferralitic weathering profiles on the Vogelsberg basaltic massif. Saprolite more than 50 m thick, was formed and, in its higher parts, bauxite concretions developed by absolute accumulation of aluminium. The tops of the profiles consist mostly of allochthonous, lateritic bauxite which has been mined intensively in the

  10. Middle and upper Miocene natural gas sands in onshore and offshore Alabama

    SciTech Connect

    Mink, R.M.; Mancini, E.A.; Bearden, B.L.; Smith, C.C.

    1988-09-01

    Thirty Miocene natural gas fields have been established in onshore and offshore Alabama since the discovery of Miocene gas in this area in 1979. These fields have produced over 16 bcf of natural gas from the middle Miocene Amos sand (24 fields) and upper Miocene Luce (3 fields), Escambia (1 field), and Meyer (3 fields) sands. Production from the Amos transgressive sands represents over 92% of the cumulative shallow Miocene natural gas produced in onshore and offshore Alabama. In addition, over 127 bcf of natural gas has been produced from upper Miocene sands in the Chandeleur area. The productive Miocene section in onshore and coastal Alabama is interpreted to present transgressive marine shelf and regressive shoreface sands. The middle Miocene Amos sand bars are the most productive reservoirs of natural gas in onshore and coastal Alabama, principally due to the porous and permeable nature of these transgressive sands and their stratigraphic relationship to the underlying basinal clays in this area. In offshore Alabama the upper Miocene sands become thicker and are generally more porous and permeable than their onshore equivalents. Because of their deeper burial depth in offshore Alabama, these upper Miocene sands are associated with marine clays that are thermally more mature. The combination of reservoir grade lithologies associated with moderately mature petroleum source rocks enhances the natural gas potential of the upper Miocene sands in offshore Alabama.

  11. Coarse-grained deltaic sedimentation in the Miocene Cuyama strike-slip basin, California Coast Ranges

    USGS Publications Warehouse

    Alan, Bartow J.

    1990-01-01

    The Cuyama basin, located in the southern Coast Ranges of California southwest of the San Andreas fault, developed early in the history of the San Andreas transform system. The Miocene marine basin formed in a transtensional setting along a dextral strike-slip fault of the transform system following Oligocene non-marine basin formation in an extensional setting. The lower and middle Miocene Vaqueros Formation in the northwestern part of the basin, which represents the first of two transgressive-regressive cycles, is described here in terms of nine facies in two broad facies groups. The 400-m-thick Soda Lake Shale Member (of the Vaqueros) comprises deep-basin and starved-basin facies. A thin transgressive facies occurs locally at the base of the formation. The overlying Painted Rock Sandstone Member (of the Vaqueros), which is more than 2200 m thick and consists mostly of coarse-grained sandstone and pebbly sandstone, constitutes a delta complex of prodelta, slope channel, delta front, tide-influenced distributary channel, interdistributary bay, and fluvial channel facies. The basinal depositional system consisted of turbidite mud and sand, and hemipelagic and pelagic sediments of the basinal facies deposited in a rapidly subsiding basin. The delta depositional system consisted of the delta complex facies that prograded into the deep basin and had a steep prodelta slope that extended to bathyal depths. The delta is inferred to be a mixed fluvial-wave-dominated fan delta, analogous in its delta-front morphology and processes to a fjord delta, in which coarse sediment delivered to the delta front by braided streams was transported down the prodelta slope into deep water by sediment gravity flows. Transgression and rapid deepening of the basin in the early Miocene coincided with rapid tectonic subsidence. Deepening culminated with deposition of a starved-basin facies or condensed section at the time of maximum transgression, which was followed by the beginning of a regression and basin shallowing. The overall basin history and geometry of the northwestern Cuyama basin are typical of strike-slip basins. The initial rapid subsidence to bathyal depths at rates of more than 500 m/m.y. in the early Miocene is interpreted to be a result of extension at the releasing bend of a dextral strike-slip fault. ?? 1990.

  12. Provenance study conflict Miocene eolian deposit in central China

    NASA Astrophysics Data System (ADS)

    Liu, S.; Stockli, D. F.; Li, J.; Song, C.

    2013-12-01

    The dispute of fine-grained Miocene sediments from Tianshui Basin, northeastern Tibetan Plateau as eolian loess-paleosol or neptunian mudflat/distal fan is an unresolved hot topic in Cenozoic palaeoclimatology , impacting further research of Asian monsoon and the mechanism of its variations. Tratigraphic correlation and constraining the sedimentary age with paleomagnetic method show that hundreds miles of foreland basin stratums occurred in north of West Qinling mountain belt in Miocene. The tratums are about 2000 m thick in the south foredeep range, thinning to less than 300 m thick in the north backbulge range. Similar heavy minerals composition and detrital ziron U/Pb ages distribution also show that the materials in the basin were from the same denuded regions. Such evidences conform that the Miocene sedimentary sections identified as loess in Tianshui basin could be distal fan and flood plain in the united foreland basin system. Comprehensive provenance techniques of heavy minerals and detrital zircon U/Pb ages show differences between Miocene Tianshui sediments and Pliocene- Quaternary loess- red clay from Chinese loess Plateau. Specifically, samples from Tianshui basin have more than 20% of Magnetite and 30% of Epidote, but Amphibole is lacking. Loess-red clay samples consist of 21% Amphibole on average. Classifying degree of correction of Amphibole proves that weathering erosion is not the reason for this dissimilarity. More Amphibole rich iginous rocks or matemorphoic rocks could exist widely in loess's source region. Most zircon U/Pb ages in this study fall into similar ranges, especially from 200Ma to 500Ma. There is a significant age peak from 200Ma to 250Ma in Tianshui sediments and modern river sands originating from West Qinling mountain belt, which is rare in loess-red clay samples. A part of zircons from loess and red clay contain very low U and Th elements, implying some of Mafic or intermediate rocks in eolian source area. Both Mafic and intermediate rocks can be found in north of Tibetan Plateau, the recommended initial source area of Quaternary loess. West Qinling mountain belt is composed mainly of Mesozoic sedimentary rocks and granite, which can only provide materials absent of amphiboles and some local peaks of zircon U/Pb ages. They have been confirmed in Tianshui Miocene samples. We propose that the materials from recommended source areas of Pliocene- Quaternary loess-red clay did not join in the Tianshui basin in Miocene. This conclusion may also challenge previous viewpoints that Asian monsoon can be dated back to early Miocene.

  13. Miocene terrestrial climate of southern New Zealand from floral proxies

    NASA Astrophysics Data System (ADS)

    Reichgelt, T.; Kennedy, E.; Conran, J. G.; Lee, D.

    2013-12-01

    Southern New Zealand is situated in the mid-latitude south-west Pacific near the convergence zone of the Sub-Antarctic Front and the Subtropical Front. Climate records from this region are therefore of considerable importance for the understanding of the development of the Antarctic Ice Sheet and the consequences of the possible future retreat of the West Antarctic Ice Sheet. Well-preserved, diverse floral assemblages from several Miocene lake deposits have been discovered in southern New Zealand: they include one from the Aquitanian (23 Ma), two from the Burdigalian (16-18 Ma) and two from the Serravallian-Early Tortonian (10-12 Ma). Climatic proxies such as Climate Leaf Analysis Multivariate Program (CLAMP) and Bioclimatic Analysis provide a robust framework with which to reconstruct the terrestrial climate of southern New Zealand through the Miocene. CLAMP employs a set of physiognomic characteristics of fossil leaves and correlates these with a large physiognomic dataset of modern floral collections and associated climate variables. Bioclimatic Analysis is a mutual climate range method using the climatic envelopes of the nearest living relatives of a fossil flora to determine the climatic range in which the flora could co-occur. It employs a comprehensive dataset of modern living taxa of the major floral components from Australia, New Zealand and New Caledonia. New Zealand was a low-lying landmass throughout the Miocene, most likely of a comparable size to modern day New Zealand. Most floral assemblages were deposited close to sea-level and climate would have been regulated by the surrounding ocean. Subtropical climatic conditions prevailed throughout the Early and Middle Miocene with mean annual temperatures (MAT) around 18-20°C and precipitation rates at around 1500-2000 mm-yr. By comparison modern day coastal southern New Zealand has a MAT of between 8-10°C and annual precipitation ranges from 600-900 mm-yr on the east coast, to well over 4000 mm-yr on the southwest coast. The temperature difference between summer and winter in the Early to Middle Miocene was less than 10°C. Towards the Late Miocene, the MAT dropped to around 15°C and the temperature during the cold season was significantly cooler, with a cold month mean of ~13-14°C in the Early and Middle Miocene and ~6°C in the Late Miocene; close to modern day New Zealand winter temperatures. Precipitation rates remained the same at around 1500-2000mm-yr. The development of the West Antarctic Ice Sheet in the Miocene was the main driver that pushed the Sub-Antarctic Front northward, while southern New Zealand's latitudinal position remained stable at close to 45°S. Antarctic southerlies would not have played a role in New Zealand's climatic system during the Early and Middle Miocene, when the average temperature of the coldest months very rarely dropped below 10°C. By the Tortonian, Antarctic southerlies would have played a significant role in cooling southern New Zealand during winter.

  14. The early to mid-Miocene environment of Antarctica

    NASA Astrophysics Data System (ADS)

    Ashworth, A. C.; Lewis, A.

    2012-12-01

    Paleoecological studies in the Transantarctic Mountains of the McMurdo region provide evidence that the climate was both warmer and wetter in the early to mid-Miocene than it was during the late Miocene. The climate change was accompanied by a shift from wet- to cold-based glaciation in the TAM and the probable growth of the polar ice sheet. Terrestrial and freshwater aquatic fossil assemblages from the Friis Hills (77°S) and the Olympus Range (77°S), with endpoint 40Ar/39Ar ages on tephras of 19.76 Ma and 14.07 Ma, respectively, indicate climatic cooling during the interval. At c.14 Ma, the temperature dropped below the threshold required to support the plants and insects of a tundra biome, and they became extinct. This interpretation is supported by pollen studies from Ross Sea cores. The extinction of the tundra biota on the continent appears to have been time-transgressive, occurring at 12.8 Ma on the Antarctic Peninsula. Evidence of climatic cooling from early to mid-Miocene is based on a decrease in biodiversity. During interglacial phases of the early Miocene, the poorly drained valley of the Friis Hills supported a sexually-reproducing moss community dominated by Campylium cf. polygamum, which today grows on the margins of lakes and in soil between boulders. Wood and leaves of Nothofagus (Southern Beech), and the seeds of at least five other angiosperm species are preserved as fossils. In addition, there are abundant megaspores and spiny, curved leaves of the aquatic lycopod Isoetes (Quillwort), as well as chitinous remains of curculionid beetles and Chironomidae (midges). During glacial phases, the only fossils found are Nothofagus leaves of a species which appears to be different than that associated with the interglacial phases. Pollen supports the interpretation that there was more than one species of Nothofagus in the vegetation. The types and numbers of species indicate that the vegetation was a shrub tundra. The closest modern analog for the fossil assemblage is at treeline and higher on Isla Navarino (55°S) at the southern tip of South America. By mid-Miocene, the upland tundra biota was less diverse, most notably in the number of angiosperm taxa. Based on the autecology and geographic distributions of the descendants of the fossil biota which survive in the subantarctic islands, South America and Tasmania, there was a decline of mean summer temperatures from c. 6°C to c. 4°C from the early to the mid-Miocene. During the early Miocene, the MST of the TAM was c.19°C warmer than today. A paleotemperature estimate based on leaf waxes from a Ross Sea core is for a MST 11°C warmer than today which seems low considering it is based on a near sea-level vegetation. A recent paper utilizing a salt-hydration process to provide adequate moisture to support a Miocene tundra biota is based on erroneous data. The Miocene climate was wet with an annual precipitation of at least 3000 mm. A recent report of the possible survival of vegetation in the Taylor Valley until the Pliocene, based on the discovery of 5 Ma wood-like forms in a DVDP core, is improbable. Even if wood can be definitively identified from the Pliocene deposits it is likely to be reworked Miocene wood from uplands in the TAM (e.g. Friis Hills). Research supported by NSF OPP 0739693.

  15. Preliminary assessment of injection, storage, and recovery of freshwater in the lower Hawthorn aquifer, Cape Coral, Florida

    USGS Publications Warehouse

    Quinones-Aponte, Vicente; Wexler, Eliezer J.

    1995-01-01

    A preliminary assessment of subsurface injection, storage and recovery of fresh canal water was made in the naturally brackish lower Hawthorn aquifer in Cape Coral, southwestern Florida. A digital modeling approach was used for this preliminary assessment, incorporating available data on hydrologic conditions, aquifer properties, and water quality to simulate density-dependent ground-water flow and advective-dispersive transport of a conservative ground-water solute (chloride ion). A baseline simulation was used as reference to compare the effects of changing various operational factors on the recovery efficiency. A recovery efficiency of 64 percent was estimated for the baseline simulation. Based on the model, the recovery efficiency increases if the injection rate and recovery rates are increased and if the ratio of recovery rate to injection rate is increased. Recovery efficiency decreases if the amount of water injected is increased; slightly decreases if the storage time is increased; is not changed significantly if the water is injected to a specific flow zone; increases with successive cycles of injection, storage, and recovery; and decreases if the chloride concentrations in either the injection water or native aquifer water are increased. In everal hypothetical tests, the recovery efficiency fluctuated between 22 and about 100 percent. Two successive cycles could bring the recovery efficiency from 60 to about 80 percent. Interlayer solute mass movement across the upper and lower boundaries seems to be the most important factor affecting the recovery efficiency. A sensitivity analysis was performed applying a technique in which the change in the various factors and the corresponding model responses are normalized so that meaningful comparisons among the responses could be made. The general results from the sensitivity analysis indicated that the permeabilities of the upper and lower flow zones were the most important factors that produced the greatest changes in the relative sensitivity of the recovery efficiency. Almost equally significant changes occurred in the relative sensitivity of the recovery efficiency when all porosity values of the upper and lower flow zones and the leaky confining units and the vertical anisotropy ratio were changed. The advective factors are the most important in the Cape Coral area according to the sensitivity analysis. However, the dispersivity values used in the model were extrapolated from studies conducted at the nearby Lee County Water Treatment Plant, and these values might not be representative of the actual dispersive characteristics of the lower Hawthorn aquifer in the Cape Coral area.

  16. A new pitheciin primate from the middle Miocene of Argentina.

    PubMed

    Kay, R F; Johnson, D; Meldrum, D J

    1998-01-01

    We report here a new fossil primate from the middle Miocene of Argentina. The material consists of isolated teeth, mandibular fragments, and a talus. The fossils were collected in the Collón Cura formation at Cañadón del Tordillo in Neuquén Province. An age of 15.71 +/- 0.07 Ma has been reported for the Pilcaniyeu Ignimbrite, which lies just below the paleosols in which the fossils were found. This material is thus the youngest occurrence of fossil primates in Argentina (hitherto documented in the Santacrucian and older land mammal ages) but still is older than the middle Miocene platyrrhine primates from La Venta, Colombia, in particular the pitheciins Nuciruptor and Cebupithecia. The material is recognized as a new genus and species of Pitheciinae, Propithecia neuquenensis. The mesiodistally compressed, high-crowned incisors are specialized and similar to species in the tribe Pithecini and to the nonpitheciin Soriacebus (early Miocene, Patagonia). We rule out a phylogenetic relationship to the latter because of differences in molar morphology. Propithecia does, however, fit well into the pattern of pitheciin evolution, being more derived than the middle Miocene pitheciin Nuciruptor but not as much as another middle Miocene taxon, Cebupithecia. As such, this makes Propithecia the oldest taxon that can be confidently placed within this modern New World monkey subfamily. By analogy with the molar structures and diets of extant platyrrhines, Propithecia has a molar structure consistent with a variety of low-fiber diets ranging from fruit and gum to seeds. Its incisors suggest seed-eating in much the same way as extant pitheciins, like Pithecia. The talus resembles that of Callicebus, suggesting arboreal quadrupedal locomotion. PMID:9702279

  17. Depositional styles from Miocene through Pleistocene in the North Central Gulf of Mexico: An historical reconstruction

    SciTech Connect

    Hunt, J.L. Jr.; Burgess, G. [Dept. of the Interior, New Orleans, LA (United States)

    1995-10-01

    During the past two years, Minerals Management Service, U.S. Department of the Interior, has classified the reservoir sands from the approximately 1,100 fields across the entire Northern Gulf of Mexico into groups of genetically related plays defined by production, chronostratigraphy, lithostratigraphy, and structure. This study was undertaken in part for the 1995 National Gas and Oil Assessment. Each field was assigned a structural code, and each producible sand was classified by depositional environment. Correlation of the composite type logs with biostratigraphic and seismic data established twelve chronozones from lower Miocene to upper Pleistocene. Sands within each chronozone were classified as transgressive, aggradational, progradational, or deep-sea fan facies. Proved reserves plays, hydrocarbon extents, as well as facies sand limits were mapped for each chronozone. Dramatic changes in depositional styles from the Miocene through the Pliocene are observed in the north-central Gulf of Mexico as the ancestral Mississippi River delta moved both basinward and eastward across offshore Louisiana. The depocenter moved back to the west and significantly basinward during the Pleistocene. Depositional patterns were strongly influenced by localized salt structure and major growth faulting. Salt ridges on the paleo-slope had a damming effect on deposition. When the ridges were breached, the focused sediment supply created areas of slope fan deposits. The results of this study are useful hydrocarbon exploration and development tools.

  18. Simultaneous Determination of Seven Components from Hawthorn Leaves Flavonoids in Rat Plasma by LC-MS/MS.

    PubMed

    Zhu, Shourong; Yan, Huiyu; Niu, Kai; Zhang, Sixi

    2015-07-01

    In this study, a simple, sensitive, and throughout liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous determination of seven flavonoid compounds, namely, rutin, vitexin-4?-O-glucoside, vitexin-2?-O-rhamnoside, hyperoside, vitexin, shanyenoside A and quercetin in rat plasma after intravenous administration of hawthorn leaves flavonoids (HLF) using lysionotin as an internal standard (IS). The target compounds were extracted using protein precipitation by methanol. The detection was achieved by LC-MS/MS in multiple reaction monitoring mode. The optimal mass transition ion pairs (m/z) for quantitation were 609.3/300.1 for rutin, 593.1/413.2 for vitexin-4?-O-glucoside, 577.3/413.2 for vitexin-2?-O-rhamnoside, 463.2/300.1 for hyperoside, 431.2/311.2 for vitexin, 407.2/245.1 for shanyenoside A, 301.1/151.1 for quercetin and 343.2/313.1 for the IS, respectively. The method was fully validated with respect to specificity, sensitivity, linearity, precision, accuracy, recovery and stability experiments. A sufficiently sensitive and selective LC-MS/MS method was first developed in this study to simultaneously evaluate the pharmacokinetics of seven flavonoids in rat plasma following intravenous administration of HLF. PMID:25368407

  19. Mid Miocene Terrestrial Ecosystems: Information from Mammalian Herbivore Communities.

    NASA Astrophysics Data System (ADS)

    Janis, C. M.; Damuth, J.; Theodor, J. M.

    2001-05-01

    In present day ecosystems the numbers and proportions of different kinds of ecologically distinct ungulates (hoofed mammals) provide an indicator of the nature of the vegetation in the habitat. Different vegetation types (such as forest, savanna, or grassland) are characteristically associated with different arrays of ungulates, with species exhibiting differences in diet, body size, and type of digestive fermentation system. These biological attributes can also be inferred for fossil ungulate species, the first two from quantitative assessment of skull and dental anatomy, and the last from phylogenetic affinity. Thus fossil ungulate communities may be used as indicators of the vegetation types of the habitats in which they lived. Vegetation types, in turn, are determined largely by a number of physical environmental factors. Typical ungulate communities of the late early to early middle Miocene (17 - 15 Ma) from the Great Plains of North America contained a diversity of browsing (leaf-eating) and grazing (grass-eating) species, with proportions of dietary types and a diversity of body sizes indicative of a woodland savanna habitat. Paleobotanical evidence also indicates a woodland savanna type of vegetation. However, these communities included a much larger number of ungulate species than can be found in any present-day community. The "excess" ungulate species were primarily browsers. Throughout the rest of the middle Miocene both species numbers and the proportion of browsers in ungulate communities appear to have declined steadily. During this decline in browser species the numbers of grazer species remained relatively constant. Within-community species numbers comparable to the present day were attained by the late Miocene. We suggest that the early Miocene browser-rich communities, and their subsequent decline, carry an important paleoenvironmental signal. In particular, communities "over rich" in browsers may reflect higher levels of primary productivity in mid Miocene vegetation types in comparison with corresponding, structurally equivalent present-day vegetation types. The observed decline in species numbers may represent a gradual decline in terrestrial primary productivity, which would be consistent with one current hypothesis of a mid-Miocene decrease in atmospheric carbon dioxide concentrations from higher mid-Cenozoic values.

  20. Late Miocene biogeography and paleoclimatology of the central North Atlantic

    USGS Publications Warehouse

    Poore, R.Z.

    1981-01-01

    Quantitative analyses of planktonic foraminiferal assemblages from Deep Sea Drilling Project (DSDP) Holes 334 and 410 demonstrate that subpolar and subtropical faunal provinces existed in the North Atlantic during the late Miocene. Climatic oscillations are clearly recorded in Hole 410 by variations in abundance of the Neogloboquadrina subpolar assemblage. These climatic oscillations have a period of about 1 m.y. Higher frequency oscillations with a periodicity of one to several hundred thousand years are evident from about 6.5 to 7.5 m.y. and are probably present throughout the entire late Miocene. A revised age of 7.0 m.y. is proposed for the first occurrence of the calcareous nannofossil Amaurolithus primus (the Amaurolithus datum). ?? 1981.

  1. The lithostratigraphy of Miocene series from Tunisia, revisited

    Microsoft Academic Search

    Beya Mannaï-Tayech

    2009-01-01

    In the Mediterranean region, the Miocene is a rather particular tectonic, eustatic and climatic epoch. In Tunisia, the complex distribution of the sedimentary sequences has been controlled by the interaction of these factors. These sequences are composed mostly of silici-clastic packages filling usually rim-syncline, graben and half-graben basins. In the absence of a solid biostratigraphic framework, the dating and correlation

  2. Extending the astronomical (polarity) time scale into the Miocene

    Microsoft Academic Search

    F. J. Hilgen; W. Krijgsman; C. G. Langereis; L. J. Lourens; A. Santarelli; W. J. Zachariasse

    1995-01-01

    An astronomical time scale is presented for the late Miocene based on the correlation of characteristic sedimentary cycle patterns in marine sections in the Mediterranean to the 65°N summer insolation curve of La90[1,2] with present-day values for the dynamical ellipticity of the Earth and tidal dissipation by the moon. This correlation yields ages for all sedimentary cycles and hence also

  3. The Proboscidea (Mammalia) from the Miocene of Sandelzhausen (southern Germany)

    Microsoft Academic Search

    Ursula B. Göhlich

    2010-01-01

    Presented here is the complete proboscidean assemblage from the vertebrate locality of Sandelzhausen (southern Germany), dated\\u000a to the Early\\/Middle Miocene boundary, early middle MN5. The material is preserved as mostly isolated and disarticulated remains\\u000a and is composed of about 200 dental remains (cheek teeth and tusks), cranial fragments, and postcrania. The main part of this\\u000a assemblage is identified as belonging

  4. Pre-transform early Miocene extension in western California

    SciTech Connect

    Tennyson, M.E. (Geological Survey, Denver, CO (USA))

    1989-09-01

    Earliest Miocene (20-24 Ma) faulting and volcanism were widespread in western California, including the San Joaquin-La Honda basin, Coast Ranges, and Transverse Ranges. Evidence for strike slip on faults of this age is lacing. Their arrangement on a pre-San Andreas restoration suggest continuity with early Miocene extended terranes in eastern California and southwestern Arizona. Deformation was probably not an effect of transform or triple-junction-migration tectonics, because it was synchronous over 300 km of latitude and there is no direct evidence for a transform boundary until late in early Miocene time. Magnetic anomalies in the eastern Pacific permit an interpretation that a spreading ridge supplied a still-active subduction zone with young oceanic crust until sometime after 20 Ma. If so, extension evidently took place in an arc-related setting. A transform regime probably formed about 18 Ma, when most basins underwent episodes of deepening or uplift, strike-slip faults became active, and rotation of the western Transverse Ranges block began.

  5. Miocene Oaks from Eastern Zhejiang, China and their Paleoenvironmental Significance

    NASA Astrophysics Data System (ADS)

    Jia, Hui; Ferguson, David

    2015-04-01

    The intertrappean fluvial-lacustrine beds belonging to the Upper Miocene Shengxian Formation in eastern China contain many exquisitely preserved plant fossils, e.g., leaves, fruits and seeds as well as plentiful pollen. The Fagaceae is the dominant taxon represented by 5 genera and 15 species, four of which belong to Quercus subgenus Cyclobalanopsis. Quercus species (oaks) are highly sensitive to environmental changes. The correlation between climate and trichome base density of Quercus glauca and Quercus delavayi of subg. Cyclobalanopsis, which are the NLRs of two fossil species, Quercus paraglauca and Quercus aff. delavayi, indicates that the trichome base density of Quercus glauca is comprehensively affected by various climate factors, but most influenced by solar radiation and latitude. The trichome base parametrics of Quercus paraglauca and the comparison of epidermal cell characteristics between Quercus paraglauca and Quercus aff. delavayi and their NLR species of subg. Cyclobalanopsis, show that the climate was warmer and more humid in the late Miocene than that of today in eastern Zhejiang, China. A study of the stomatal index of Quercus glauca and Quercus delavayi, collected in different years, demonstrates that they are very sensitive to the variation of atmospheric CO2 concentration. By comparing the stomatal ratio between the two fossil species and their NLRs, the paleoatmospheric CO2 concentration in the late Miocene is reconstructed as ca. 400 ppmv, i.e. higher than the present natural CO2 concentration eliminating the industrial influence.

  6. Diagenesis in upper Miocene sandstones, Louisiana Gulf Coast

    SciTech Connect

    Gold, P.B.

    1985-02-01

    Study of diagenesis in upper Miocene sandstones of coastal Louisiana documents depth-related cementation and geochemical changes of primary detrital mineralogy. Samples were collected from depths of 8000-20,000 ft (2600-6500 m) in an area roughly corresponding to the upper Miocene depocenter in the Terrebonne trough of southeast Louisiana. Sandstones are primarily subarkoses and sublitharenites with minor amounts of feldspathic litharenites and lithic arkoses. Plagioclase feldspar (oligoclase/andesine composition) composes approximately 60% of the detrital feldspar. Dominant rock fragments are siltstone or mudstone, silicified volcanic rock, and chert. Authigenic minerals and cements occur in the following order: dolomite, chlorite grain coats, albite overgrowths on plagioclase and K-feldspar, quartz, calcite, kaolinite, and ankerite. Calcite composition remains nearly constant with depth, but ankerite composition differs both with depth and within individual samples. In general, the mineralogy and order of cements resemble that of the lower Tertiary sandstones of the Texas Gulf Coast; however, in the upper Miocene, the volume of each cement is much less and the depth of first occurrence is greater. Feldspars have reacted substantially with pore fluids. With increasing depth, feldspar becomes more sodic because of albitization and dissolution of calcic plagioclase. At approximately 20,000 ft, 75% of the plagioclase is nearly pure albite. Alteration of K-feldspar is not common above 17,000 ft; below 17,000 ft occurrences are rare because of dissolution.

  7. Early Miocene elevation in northern Tibet estimated by palaeobotanical evidence.

    PubMed

    Sun, Bin; Wang, Yu-Fei; Li, Cheng-Sen; Yang, Jian; Li, Jin-Feng; Li, Ye-Liang; Deng, Tao; Wang, Shi-Qi; Zhao, Min; Spicer, Robert A; Ferguson, David K; Mehrotra, Rakesh C

    2015-01-01

    The area and elevation of the Tibetan Plateau over time has directly affected Asia's topography, the characteristics of the Asian monsoon, and modified global climate, but in ways that are poorly understood. Charting the uplift history is crucial for understanding the mechanisms that link elevation and climate irrespective of time and place. While some palaeoelevation data are available for southern and central Tibet, clues to the uplift history of northern Tibet remain sparse and largely circumstantial. Leaf fossils are extremely rare in Tibet but here we report a newly discovered early Miocene barberry (Berberis) from Wudaoliang in the Hoh-Xil Basin in northern Tibet, at a present altitude of 4611?±?9?m. Considering the fossil and its nearest living species probably occupied a similar or identical environmental niche, the palaeoelevation of the fossil locality, corrected for Miocene global temperature difference, is estimated to have been between 1395 and 2931?m, which means this basin has been uplifted ~2-3?km in the last 17 million years. Our findings contradict hypotheses that suggest northern Tibet had reached or exceeded its present elevation prior to the Miocene. PMID:25976244

  8. Regional geological framework and petroleum geology of Miocene sandstones in coastal and offshore Alabama

    SciTech Connect

    Mancini, E.A.; Bearden, B.L.; Mink, R.M.

    1987-05-01

    The Miocene natural gas trend of coastal and offshore Alabama is part of the regional Miocene oil and gas trend of the Gulf coastal area that extends from Texas into Alabama. The major Miocene productive area in Alabama is in southern Baldwin County and Mobile Bay. Since the discovery of Miocene gas in 1979, 28 natural gas fields have been established in coastal and offshore Alabama. The Miocene sandstones range in thickness from 10 to 200 ft, are very fine to coarse grained, are quartz rich, and have subangular to rounded and moderately to well-sorted quartz grains. The productive Miocene interval overlies upper Oligocene marine shelf deposits (Chickasawhay Limestone) and is overlain by Miocene fluvial clastics. The Miocene sandstones, which include the Amos, Escambia, Luce, and Meyer, are interpreted to represent a marine shelf-deltaic complex. A Miocene delta system prograded from the west in the area of offshore Louisiana-Mississippi into coastal and offshore Alabama. Reservoirs and potential reservoirs include highly constructive and highly destructive deltaic and marine shelf sandstones. Porosity in these sandstones is primary intergranular and generally ranges from 27 to 35%. Permeabilities may exceed 2000 md. Basinal Miocene marine clays and Oligocene marls are the probable petroleum source rocks. Petroleum traps are principally stratigraphic, typically involving lateral sandstone pinch-outs against regional dip. Seismic reflection is an excellent exploration tool for identifying potential Miocene fields. Miocene gas sands are best delineated with relative-amplitude seismic reflection data on which gas-charged sands are apparent as bright spots.

  9. Astronomical tuning of the La Vedova High Cliff section (Ancona, Italy)--Implications of the Middle Miocene Climate Transition for Mediterranean sapropel formation

    E-print Network

    Utrecht, Universiteit

    Miocene Climate Transition for Mediterranean sapropel formation A.A. Mourik a, , J.F. Bijkerk a , A: Middle Miocene Mediterranean astronomical tuning paleomagnetism biostratigraphy environmental changes orbital forcing sapropels Continuous marine successions covering the Middle Miocene Climate Transition

  10. Simultaneous determination and pharmacokinetic comparisons of multi-ingredients after oral administration of radix salviae miltiorrhizae extract, hawthorn extract, and a combination of both extracts to rats.

    PubMed

    Liu, Yu-Qiang; Cai, Qian; Liu, Chang; Bao, Feng-Wei; Zhang, Zhen-Qiu

    2014-01-01

    A simple and sensitive HPLC method was developed for simultaneous determination of danshensu (DSS), rosmarinic acid (RA), lithospermic acid (LA), salvianolic acid B (SAB), and hyperoside (HP) in rat plasma. This method validated was successfully applied to the pharmacokinetic study of the main active ingredients after oral administration of Radix Salviae Miltiorrhizae extract (SME), hawthorn extract (HTE), and a combination of both extracts (2.5?:?1) to rats. The results indicated that there have been great differences in pharmacokinetics between a single extract and a combination of both extracts. A combination of both extracts can enhance their bioavailabilities and delay the elimination of SAB and DSS in rats. PMID:24660090

  11. Simultaneous Determination and Pharmacokinetic Comparisons of Multi-Ingredients after Oral Administration of Radix Salviae Miltiorrhizae Extract, Hawthorn Extract, and a Combination of Both Extracts to Rats

    PubMed Central

    Liu, Yu-Qiang; Cai, Qian; Liu, Chang; Bao, Feng-Wei; Zhang, Zhen-Qiu

    2014-01-01

    A simple and sensitive HPLC method was developed for simultaneous determination of danshensu (DSS), rosmarinic acid (RA), lithospermic acid (LA), salvianolic acid B (SAB), and hyperoside (HP) in rat plasma. This method validated was successfully applied to the pharmacokinetic study of the main active ingredients after oral administration of Radix Salviae Miltiorrhizae extract (SME), hawthorn extract (HTE), and a combination of both extracts (2.5?:?1) to rats. The results indicated that there have been great differences in pharmacokinetics between a single extract and a combination of both extracts. A combination of both extracts can enhance their bioavailabilities and delay the elimination of SAB and DSS in rats. PMID:24660090

  12. Screening and structural characterization of ? -glucosidase inhibitors from hawthorn leaf flavonoids extract by ultrafiltration LC-DAD-MS n and SORI-CID FTICR MS

    Microsoft Academic Search

    Huilin Li; Fengrui Song; Junpeng Xing; Rong Tsao; Zhiqiang Liu; Shuying Liu

    2009-01-01

    In vitro ?-glucosidase inhibition assays and ultrafiltration liquid chromatography with photodiode array detection coupled to electrospray\\u000a ionization tandem mass spectrometry (ultrafiltration LC-DAD-ESI-MS\\u000a n\\u000a ) were combined to screen ?-glucosidase inhibitors from hawthorn leaf flavonoids extract (HLFE). As a result, four compounds\\u000a were identified as ?-glucosidase inhibitors in the HLFE, and their structures were confirmed to be quercetin-3-O-rha- (1-4)-glc-rha\\u000a and C-glycosylflavones

  13. Long-period eccentricity control on sedimentary sequences in the continental Madrid Basin (middle Miocene, Spain)

    E-print Network

    Utrecht, Universiteit

    forcing continental paleoenvironments cyclostratigraphy eccentricity middle Miocene Madrid Basin. Introduction Orbital forcing of paleoenvironments is increasingly documented in well-dated, continental

  14. Biofacies zonation of middle Miocene benthic foraminifera, southeastern San Joaquin basin, California

    SciTech Connect

    Olson, H.C.

    1987-05-01

    The quantitative distribution of benthic foraminifera across the middle Miocene margin of the southeastern San Joaquin basin constitutes a useful tool in applying benthic biofacies zonation to the interpretation of marine paleoenvironments. A middle Miocene transect (near the Luisian/Relizian boundary) was completed across the margin of the southeastern San Joaquin basin near Bakersfild, California. Surface and subsurface fauna encompass strandline through bathyal environments. Quantitative analyses of these fauna result in a useful biofacies zonation for the middle Miocene which can be applied to the interpretation of middle Miocene paleobathymetric and paleogeographic reconstructions, basin analysis, and subsidence histories of the San Joaquin basin. In addition, these data suggest that vertical faunal migration of continental slope fauna has occurred between the middle Miocene and Recent. During the early and middle Miocene, marine temperatures were warmer than today and lower latitudinal gradients prevailed. Stepwise climatic cooling since the middle Miocene has been accompanied by the latitudinal adjustment of surface isotherms, strengthening of the permanent thermocline, and the associated migration of temperature-sensitive planktonic and benthic biofacies. Sedimentologic and seismic evidence in the southeastern San Joaquin basin suggests that present-day lower bathyal biofacies may have been at shallower depths during the middle Miocene. Such migrations would have a significant impact on paleoenvironmental interpretations. Middle Miocene faunal transects from the southeastern San Joaquin basin are compared with equivalent Holocene transects from the eastern Pacific, and differences are discussed in light of this proposal.

  15. Petrology of Early Miocene volcanic rocks from Okushiri Island, Japan: geochemical characteristics of lithospheric mantle beneath the back-arc side of the NE Japan arc.

    NASA Astrophysics Data System (ADS)

    Sato, M.; Shuto, K.; Ishimoto, H.; Yagi, M.; Takazawa, E.

    2004-12-01

    The Sr and Nd isotopic studies on Tertiary to Quaternary basaltic rocks of the NE Japan arc have shown that isotopic characteristics of basaltic rocks found on the back-arc side of the NE Japan arc changed drastically from an undepleted isotopic signature (initial 87Sr/86Sr (SrI)=0.7040-0.7060 and initial 143Nd/144Nd (NdI)=0.51260-0.51284) to a depleted isotopic signature (SrI=0.7030-0.7040 and NdI=0.70284-0.51308) at around 15 Ma (Shuto et., 2004). This feature may have resulted from changes around 15 Ma in the isotopic compositions of the magma source beneath the back-arc side in the NE Japan arc due to the thinning of the undepleted subcontinental lithospheric mantle by upwelling of depleted asthenospheric mantle material during the opening of Japan Sea. Based on major and trace element data as well as SrI and NdI values for Early Miocene basaltic rocks from the back-arc side of the NE Japan arc, we examined geochemical characterization of the magma source (lithospheric mantle) for these basaltic rocks. Early Miocene (23-18 Ma) basalts and associated more felsic volcanic rocks form seven volcanic fields (Okushiri Is., Matsumae Pen., Fukaura, Oga Pen., Honjo, Atsumi and Sado Is.) delineating a 500 km-long array in the back-arc side of the NE Japan arc. In terms of major, trace element and Nd isotopic compositions, two groups of Early Miocene basalts can be distinguished. Group 1 is composed of tholeiitic basalts and alkali basalts, and is characterized by high TiO2 contents (1.5-2.5 %) and high (La/Yb)n ratios (>5.5), and high Zr/Y ratios (>6). These samples show the chondrite-normalized LREE-enriched patterns and have NdI values ranging from 0.51259 to 0.51282. Group 2 is composed of tholeiitic basalts, and is different from Group 1 by lower TiO2 contents (<1.5 %), lower (La/Yb)n ratios (<5) and lower Zr/Y ratios (<5.5). These samples show modelately LREE-enriched patterns and have NdI values ranging from 0.51250 to 0.51278. In contrast, Middle Miocene (after 15 Ma) basaltic rocks from the Niigata and Honjo areas in the back-arc side of the NE Japan arc have NdI values of 0.51286 to 0.51310, which are higher than those of Early Miocene basalts. These Middle Miocene samples are lower in TiO2 contents and (La/Yb)n and Zr/Y ratios than Early Miocene Group 1 samples, but partly overlap with Early Miocene Group 2 samples. The geochemical differences between Group 1 and 2 basalt magmas possibly originated from subcontinental lithospheric mantle may be due to differences in degrees of partial melting or heterogeneity of the mantle.

  16. Palaeoenvironmental shifts drove the adaptive radiation of a noctuid stemborer tribe (Lepidoptera, Noctuidae, Apameini) in the miocene.

    PubMed

    Toussaint, Emmanuel F A; Condamine, Fabien L; Kergoat, Gael J; Capdevielle-Dulac, Claire; Barbut, Jérôme; Silvain, Jean-François; Le Ru, Bruno P

    2012-01-01

    Between the late Oligocene and the early Miocene, climatic changes have shattered the faunal and floral communities and drove the apparition of new ecological niches. Grassland biomes began to supplant forestlands, thus favouring a large-scale ecosystem turnover. The independent adaptive radiations of several mammal lineages through the evolution of key innovations are classic examples of these changes. However, little is known concerning the evolutionary history of other herbivorous groups in relation with this modified environment. It is especially the case in phytophagous insect communities, which have been rarely studied in this context despite their ecological importance. Here, we investigate the phylogenetic and evolutionary patterns of grass-specialist moths from the species-rich tribe Apameini (Lepidoptera, Noctuidae). The molecular dating analyses carried out over the corresponding phylogenetic framework reveal an origin around 29 million years ago for the Apameini. Ancestral state reconstructions indicate (i) a potential Palaearctic origin of the tribe Apameini associated with a major dispersal event in Afrotropics for the subtribe Sesamiina; (ii) a recent colonization from Palaearctic of the New World and Oriental regions by several independent lineages; and (iii) an ancestral association of the tribe Apameini over grasses (Poaceae). Diversification analyses indicate that diversification rates have not remained constant during the evolution of the group, as underlined by a significant shift in diversification rates during the early Miocene. Interestingly, this age estimate is congruent with the development of grasslands at this time. Rather than clade ages, variations in diversification rates among genera better explain the current differences in species diversity. Our results underpin a potential adaptive radiation of these phytophagous moths with the family Poaceae in relation with the major environmental shifts that have occurred in the Miocene. PMID:22859979

  17. Hawthorn (Crataegus oxyacantha L.) bark extract regulates antioxidant response element (ARE)-mediated enzyme expression via Nrf2 pathway activation in normal hepatocyte cell line.

    PubMed

    Krajka-Ku?niak, Violetta; Paluszczak, Jaros?aw; Oszmia?ski, Jan; Baer-Dubowska, Wanda

    2014-04-01

    Hawthorn (Crataegus oxyacantha L.), a plant used in traditional medicine, is a rich source of procyanidins which have been reported to exhibit antioxidant and anti-carcinogenic activity. In this study, we assessed the effect of hawthorn bark extract (HBE) on Nrf2 pathway activation in THLE-2 and HepG2 cells. Treatment with 1.1 µg/mL, 5.5 µg/mL and 11 µg/mL of HBE resulted in the translocation of Nrf2 from the cytosol to the nucleus in both cell lines; however, the accumulation of phosphorylated Nrf2 was observed only in THLE-2. Accordingly, treatment of cells with HBE was associated with an increase in the mRNA and protein level of such Nrf2-dependent genes as glutathione S-transferases (GSTA, GSTP, GSTM, GSTT), NAD(P)H:quinone oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1) (0.2-1.1-fold change, p?

  18. Differential effects of polyphenols-enriched extracts from hawthorn fruit peels and fleshes on cell cycle and apoptosis in human MCF-7 breast carcinoma cells.

    PubMed

    Li, Ting; Zhu, Jiao; Guo, Ling; Shi, Xiaolong; Liu, Yafei; Yang, Xingbin

    2013-11-15

    This study was to investigate the anticancer effects of the peel polyphenolic extract (HPP) and flesh polyphenolic extract (HFP) from hawthorn fruit in human MCF-7 breast cancer cells. It was found that the polyphenol and flavonoid contents of HPP were significant higher than that of HFP. Both HPP and HFP inhibited cell growth in a dose-dependent manner with the IC50 of 88.6?g/mL and 175.5?g/mL, respectively, suggesting that HPP was more effective against MCF-7 cells than HFP. Flow cytometric analysis revealed that both HPP and HFP mediated the cell-cycle arrest at the S-phase, and also dose-dependently led to apoptosis of MCF-7 cells via the mitochondrial pathway, as evidenced by the activation of caspase-3 and caspase-9 and the elevation of intracellular ROS production. All these findings indicate that hawthorn fruit, especially its peel, is an excellent source of natural chemopreventive agents in the treatment of breast cancer. PMID:23790880

  19. Sedimentary fabric analyses of two Miocene coals from NW Taiwan

    SciTech Connect

    Tsai, L.L. [National Central Univ., Chungli (Taiwan, Province of China). Inst. of Applied Geology

    1994-12-31

    Coal is very sensitive to the environmental temperature and pressure changes during coalification. Reflectance indicatrix of vitrinite had been proved to be able to indicate those environmental conditions. In addition, characteristics of maceral types such as their composition and arrangements can further provide some insight about the stratigraphic sequence, tectonic stress, metamorphic maturity, and burial history of their sedimentary environment. Two of the major Miocene coal-bearing formations in Taiwan, i.e., the Nanchuang and the Shihti Formations, are well-developed and outcrop in the northwestern part of Taiwan. They had been subjected to several periods of orogenic disturbances so that the geologic structures are complicated with the occurrence of large scale faults and intensive folds. Igneous activities are expected to further increase the rank of coal and resulting the rearrangements the aromatic micelles in coal. Coal and coal-bearing sedimentary rock samples, mostly from Miocene Nanchuang and Shihti Formations,were collected between Taipei and Miaoli, on the northwestern part of the Western Foothill Belt of Taiwan. Sedimentary fabric analyses were then performed by using a Galai Scan-array 2 image analyzing software equipped with a CCD camera, a TV monitor, a 486 PC and a reflecto-refractive polarized microscope. The particle size (maximum feret diameter), aspect ratio (or sphericity), shape factor (or roundness) and special linear orientation of sporinites were studied. Statistically significant results were analyzed and compared among different sampling sites and stratigraphic formations. A synthetic conclusion concerning the burial history during and after Miocene were thus derived.

  20. Middle Miocene closure of the Central American Seaway

    NASA Astrophysics Data System (ADS)

    Montes, C.; Cardona, A.

    2014-12-01

    The final closure of the Panama Isthmus and permanent separation of Caribbean and Pacific waters is thought to have modified their salinity, faunistic assemblages, and ultimately, ocean circulation patterns and global climate. The Great American Biotic Interchange (GABI) is thought to have been the result of Plio-Pleistocene closure of the Isthmus that allowed land animals to massively cross the Isthmus. Similarly, the separation of Caribbean and Pacific waters by a rising Isthmus is thougth to be a prime example of vicariance. The role of Isthmus closure on global changes, however, remains controversial due in part to the difficulty of establishing a precise chronology of seaway closure. While timing of glaciation is well established, new data on the chronology of Isthmus emergence suggests that the process of closure is more complex, long, and old than previously thought. We sampled fluvial and shallow marine strata in northwesternmost South America to recover zircon grains for provenance analyses in the immediate vicinity of the docking site. Because the ages of magmatic provinces in northwestern South America and the Panama Isthmus are mutually exclusive, detrital zircon analyses provides a tool to evaluate land connections. We found that an uniquely Panamanian, 40-45 Ma (early Lutetian) detrital zircon fingerprint is abundant in middle Miocene strata, but absent in underlying lower Miocene and Oligocene strata of the northern Andes. This fingerprint represents the beginning of fluvial detrital exchange between the Panama arc and South America, and therefore marks the time of docking and the end of deep-water, and probably shallow-water connections by middle Miocene times.

  1. Composition and provenance of the Puente Formation (Miocene), Los Angeles Basin

    SciTech Connect

    Critelli, S. (Instituto de Rierca per la Protezione Idrogeologica Nell'Italia Meridionale ed Insulare, Roges de Rende (Italy)); Rumelhart, P.E.; Ingersoll, R.V. (Univ. of California, Los Angeles, CA (United States))

    1994-04-01

    The Puente Formation (PFm) is a middle to upper Miocene clastic unit lying unconformably on the middle to lower Miocene El Modeno Volcanics and Topanga Group, within the Los Angeles basin (LAB). The PFm, about 3900m thick, is composed of sandstone, conglomerate, and mudrock deposited on a submarine fan at bathyal depths. Several intrabasinal discordances suggest active tectonics during deposition. The succession consists of two main upward thickening and coarsening megacycles reflecting submarine fan progradation. The PFm is characterized up-section by: (1) thin-bedded fine sandstone and shale (La Vida M.) grading to thick-bedded coarse sandstone an conglomerate (soquel M.); (2) thin-bedded siltstone, mudrock and sandstone (Yorba M.) grading to thick- to very thick-bedded coarse-grained sandstone and conglomerate (Sycamore Canyon M.). Sandstones of the PFm are quartzofeldspathic and suggest a probable local provenance from the plutonic, volcanic, and metamorphic rocks of the San Gabriel Mountains. Petrological parameters, however, suggest variable contribution of these source rock units through time. Coarse-grained plutonic rock fragments are abundant for the entire succession and consist of plagioclase-rich plutonic rocks perhaps sourced from the Lowe granodiorite. Microlitic, lathwork to felsitic volcanic lithic grains are also present in the lower and middle part. In the Yorba M. there is a local increase of volcanic detritus (Lv/L - 0.80), represented by larger volcanic lithics and abundant volcaniclastic matrix. Metamorphic detritus is not very abundant; it is concentrated in the La Vida M. the PFm represents sedimentation during tectonically active time in the evolution of southern California.

  2. 27. MIOCENE BENTHIC FORAMINIFER OXYGEN AND CARBON ISOTOPES, SITE 709, INDIAN OCEAN1

    Microsoft Academic Search

    Fay Woodruff; Samuel M. Savin; Linda Abel

    The benthic isotopic record of Miocene Cibicidoides from Site 709 provides a record of conditions in the Indian Ocean at a depth of about 3200 mbsf. As expected, the record qualitatively resembles those of other Deep Sea Drilling Project and Ocean Drilling Program sites. The data are consistent with the scenario for the evolution of thermohaline circulation in the Miocene

  3. Dietary resource partitioning in ruminant communities of Miocene wetland and karst palaeoenvironments in Southern Germany

    Microsoft Academic Search

    Thomas M. Kaiser; Gertrud E. Rössner

    2007-01-01

    Ruminants made up a major component in Early and Middle Miocene European land mammal faunas. Hypotheses are tested which concern the diversity of feeding niches in Miocene ruminants and their resource partitioning. Because teeth are the basis of taxonomic work in the biota investigated here, the tooth-based mesowear method of dietary evaluation is applied. Dental wear equilibria as evaluated using

  4. A Miocene tectonic inversion in the Ionian Sea (central Mediterranean): Evidence from

    E-print Network

    Brest, Université de

    A Miocene tectonic inversion in the Ionian Sea (central Mediterranean): Evidence from multichannel (2011), A Miocene tectonic inversion in the Ionian Sea (central Mediterranean): Evidence from [Serpelloni et al., 2007; D'Agostino et al., 2008, 2011]. [3] Within the Ionian Sea, the Mediterranean Ridge

  5. The Late Miocene paleoenvironment of Afghanistan as inferred from dental microwear in artiodactyls

    Microsoft Academic Search

    Gildas Merceron; Cécile Blondel; Michel Brunet; Sevket Sen; Nikos Solounias; Laurent Viriot; Emile Heintz

    2004-01-01

    Dental microwear of Late Miocene artiodactyls from Afghanistan can yield information on paleodiet and thus inferences can be drawn about their paleoenvironment. The “Molayan” locality lies at the border between the Greek–Iranian and Siwalik bioprovinces. Knowledge of the paleoenvironment will further our understanding of the faunal exchanges between these two provinces during the Late Miocene. Ninety-nine specimens of seven bovid

  6. Carbon dioxide and polar cooling in the Miocene - The Monterey hypothesis

    Microsoft Academic Search

    E. Vincent; W. H. Berger

    1985-01-01

    An evaluation is made of the viability of the Monterey hypothesis, according to which the early Miocene carbon isotope shift is related to the onset of upwelling and to climatic developments. The present endorsement of the hypothesis has its basis in the correlation of the early to mid-Miocene carbon isotope excursion with the facies development in the Monterey Formation, as

  7. Tectono-sedimentary characteristics of Late Miocene-Quaternary extensional basins of the Northern Apennines, Italy

    Microsoft Academic Search

    I. P. Martini; M. Sagri

    1993-01-01

    Extensional and compressional regimes exist at the same time in adjacent parts of the Northern Apennines (Italy), and the former regime succeeded the latter at the same place as the thrust mountain front moved eastward since Miocene times. Numerous extensional basins have developed west of the present mountain divide. The westernmost ones formed over attenuated continental crust since Late Miocene

  8. Palaeogeographical implications of the Miocene Quendeque Formation (Bolivia) and tidally-influenced strata in southwestern Amazonia

    Microsoft Academic Search

    Jussi Hovikoski; Matti Räsänen; Murray Gingras; Shirley Lopéz; Lidia Romero; Alceu Ranzi; Janira Melo

    2007-01-01

    The Miocene palaeogeography of the western Amazonian Foreland Basin (Venezuela, Colombia, Ecuador, Peru and western Brazil) and the Paraná Basin (mainly Argentina) are contentious. Several studies have hypothesized for and against a possible connection of these epicontinental depositional systems during Miocene. However, the lack of well defined palaeoenvironmental data, especially from the Bolivian lowlands, has hindered the delineation of the

  9. Miocene reef facies of pelagian block, central Mediterranean

    SciTech Connect

    Pedley, H.M.

    1988-02-01

    Miocene reefs outcrop in the Maltese Islands, southeastern Sicily, and the pelagian island of Lampedusa. Several rapid eustatic sea level fluctuations affected these late Tortonian-early Messinian build-ups; normal salinities appear to have been maintained during these events. In addition to sea floor topography, reef development appears to have been controlled by turbulence. Encruster-dominated patch reefs are typical of platform and shallow ramp situations where turbulence is high. Branching and massive coral assemblages are typical of fore-reef curtains and steep slope substrates.

  10. TECTONICS,VOL. 6, NO. 6, PAGES707-725, DECEMBER1987 MODELS OF POST-MIOCENE DEFORMATION OF

    E-print Network

    Ze'ev, Reches

    TECTONICS,VOL. 6, NO. 6, PAGES707-725, DECEMBER1987 MODELS OF POST-MIOCENE DEFORMATION to the Zagros in the northeast. The post-Miocene tectonic pattern of this region includes contin- uing uplift of the lithosphere. The models indicate that the post-Miocene deformation occurs by the combined effects of lateral

  11. High-resolution ice-volume estimates for the early Miocene: Evidence for a dynamic ice sheet in Antarctica

    E-print Network

    Massachusetts at Amherst, University of

    High-resolution ice-volume estimates for the early Miocene: Evidence for a dynamic ice sheet; accepted 8 July 2005 Abstract Ice-volume estimates for the early Miocene (23­16 Ma ATS) were determined Sheet (EAIS) during most of the early Miocene (23­17 Ma). Maximum ice- volume occurred at each

  12. ELSEVIER Marine Micropaleontology 27 (1996) 253-27 1 Miocene and Pliocene paleoclimate of the Dry Valleys region,

    E-print Network

    Marchant, David R.

    1996-01-01

    ELSEVIER Marine Micropaleontology 27 (1996) 253-27 1 Miocene and Pliocene paleoclimate of the Dry. Instead, Zone 3 shows Miocene- and Pliocene-age sand wedges, avalanche cones, and desert pavements. The mid-Miocene landsurface of Zone 3 is preserved to a remarkable degree. The antiquity and longevity

  13. Bayesian Parameter Estimation in a 1D Model of Precipitation and Evaporation: Comparison of Middle Miocene and Modern

    E-print Network

    Blais, Brian

    Miocene and Modern Climates Using Plant Lipid Deuterium ( ) Measurements Brian Blais1,2, Colin Gannon1 that have been observed over the past hundred years. The Middle Miocene Climate Optimum, approximately 15. These values are obtained from n-alkanes extracted both from well-preserved Middle Miocene plant fossils

  14. Sedimentation/preservation of the Miocene Atacama Gravels in the Pedernales-Chaaral Area, Northern Chile: Climatic or Tectonic

    E-print Network

    Paris-Sud XI, Université de

    Sedimentation/preservation of the Miocene Atacama Gravels in the Pedernales-Chañaral Area, Northern blanket of Miocene continental deposits filling a Neogene paleo-valley system along the southern Atacama ignimbrites date the beginning of the Atacama Gravels sedimentation at around the Oligocene- Miocene boundary

  15. Palaeoreas lindermayeri (Wagner, 1848) (Mammalia, Bovidae) from the upper Miocene of Bulgaria, and a revision of the species

    E-print Network

    Paris-Sud XI, Université de

    Palaeoreas lindermayeri (Wagner, 1848) (Mammalia, Bovidae) from the upper Miocene of Bulgaria in the upper Miocene of Hadjidimovo-1 by what may be the largest known sample of a fossil Bovid species from saurait être rattaché à une tribu moderne. KEY-WORDS : Late Miocene, Bulgaria, Mammalia, Bovidae

  16. TIMING OF CHANGES IN SEA-LEVEL AND CURRENTS ALONG MIOCENE PLATFORMS ON THE MARION PLATEAU, AUSTRALIA

    E-print Network

    Wehrli, Bernhard

    TIMING OF CHANGES IN SEA-LEVEL AND CURRENTS ALONG MIOCENE PLATFORMS ON THE MARION PLATEAU-to-slope transects of the Miocene carbonate platforms on the Marion Plateau, situated just seaward from the Great-D) are subdivided into 14 unconformity-bounded sequences. The early to middle Miocene sequences are prograding

  17. Integrated stratigraphy of the Early Miocene lacustrine deposits of Pag Island (SW Croatia): Palaeovegetation and environmental changes in the

    E-print Network

    Utrecht, Universiteit

    Integrated stratigraphy of the Early Miocene lacustrine deposits of Pag Island (SW Croatia Orbital forcing Long-lived lakes Dinaride Lake System Early Miocene Croatia An integrated stratigraphic and that it corresponds to the Burdigalian Stage of the Early Miocene, and the regional Karpatian Stage of the Central

  18. ON SOME SPIRAL-HORNED ANTELOPES (MAMMALIA : ARTIODACTYLA : BOVIDAE) FROM THE LATE MIOCENE OF TURKEY, WITH REMARKS ON THEIR DISTRIBUTION

    E-print Network

    Paris-Sud XI, Université de

    ON SOME SPIRAL-HORNED ANTELOPES (MAMMALIA : ARTIODACTYLA : BOVIDAE) FROM THE LATE MIOCENE OF TURKEY-409" #12;ABSTRACT Examination of some collections from several late Miocene Turkish localities allows us. During the first part of the late Miocene, several endemic species are restricted to central Anatolia

  19. Age at first molar emergence in early Miocene Afropithecus turkanensis and life-history evolution in the Hominoidea

    E-print Network

    Smith, Tanya M.

    Age at first molar emergence in early Miocene Afropithecus turkanensis and life-history evolution by Sivapithecus parvada (Function, Phylogeny, and Fossils: Miocene Hominoid Evolution and Adaptations, 1997, 173. 2003 Elsevier Science Ltd. All rights reserved. Keywords: Miocene hominoid; dentition; dental eruption

  20. Timing and magnitude of Miocene eustasy derived from the mixed siliciclastic-carbonate stratigraphic record of the northeastern Australian margin

    E-print Network

    Leckie, Mark

    Timing and magnitude of Miocene eustasy derived from the mixed siliciclastic amplitude of sea-level change ice volume sequence stratigraphy Heterozoan carbonates Miocene ODP Leg 194 controversial, especially for the Miocene Epoch. We analyzed sediment cores recovered from the Marion Plateau

  1. Early Miocene sequence development across the New Jersey margin

    USGS Publications Warehouse

    Monteverde, D.H.; Mountain, Gregory S.; Miller, K.G.

    2008-01-01

    Sequence stratigraphy provides an understanding of the interplay between eustasy, sediment supply and accommodation in the sedimentary construction of passive margins. We used this approach to follow the early to middle Miocene growth of the New Jersey margin and analyse the connection between relative changes of sea level and variable sediment supply. Eleven candidate sequence boundaries were traced in high-resolution multi-channel seismic profiles across the inner margin and matched to geophysical log signatures and lithologic changes in ODP Leg 150X onshore coreholes. Chronologies at these drill sites were then used to assign ages to the intervening seismic sequences. We conclude that the regional and global correlation of early Miocene sequences suggests a dominant role of global sea-level change but margin progradation was controlled by localized sediment contribution and that local conditions played a large role in sequence formation and preservation. Lowstand deposits were regionally restricted and their locations point to both single and multiple sediment sources. The distribution of highstand deposits, by contrast, documents redistribution by along shelf currents. We find no evidence that sea level fell below the elevation of the clinoform rollover, and the existence of extensive lowstand deposits seaward of this inflection point indicates efficient cross-shelf sediment transport mechanisms despite the apparent lack of well-developed fluvial drainage. ?? 2008 The Authors. Journal compilation ?? 2008 Blackwell Publishing.

  2. Miocene to Pliocene osmium isotopic records of Mediterranean sediments

    NASA Astrophysics Data System (ADS)

    Kuroda, Junichiro; Jiménez-Espejo, Francisco J.; Nozaki, Tatsuo; Gennari, Rocco; Lugli, Stefano; Manzi, Vinicio; Roveri, Marco; Flecker, Rachel; Suzuki, Katsuhiko; Yoshimura, Toshihiro; Sierro, Francisco; Ohkouchi, Naohiko

    2015-04-01

    In the late Miocene the Mediterranean Sea experienced a salinity crisis and thick sequences of evaporites precipitated across the basin. In this study we report Os isotopic records from drilled cores in the Mediterranean; the Balearic Sea, the Tyrrhenian Sea, the Ionian Basin and the Florence Rise. Pliocene sediments at all sites show 187Os/188Os values close to that of the coeval ocean water, indicating that the Mediterranean was connected to the North Atlantic. Evaporitic sediments deposited during the late Miocene however, have 187Os/188Os values lower than coeval ocean water values and samples from the eastern Mediterranean and Ionian basins are particularly low. Os isotopic ratios of the pre-evaporite sediments in the western Mediterranean are almost identical to that of the coeval ocean water. In contrast, equivalent sediments from the Florence Rise have significantly lower 187Os/188Os values. The offset of Mediterranean evaporite 187Os/188Os is attributed to limited exchange with the North Atlantic during the Messinian Salinity Crisis (MSC). The source of unradiogenic Os is likely to be weathering of ultramafic rocks (ophiolites) cropping out in the Mediterranean's drainage basins. The offset in the Os ratio on the Florence Rise is attributed either to limited water exchange between eastern and western Mediterranean, or to local effects associated with exhumation of ophiolites around the eastern Mediterranean Sea.

  3. Plate-induced Miocene extension in southern California

    SciTech Connect

    Stuart, W.D. (Geological Survey, Pasadena, CA (United States) Univ. of California, Santa Barbara, CA (United States))

    1992-01-01

    Miocene crustal extension in southern California can be explained by the interaction of tectonic plates in relative motion. The Pacific, Juan de Fuca, and Farallon (Guadalupe) plates are represented by flat elastic plates surrounded by an infinite elastic plate, the eastern part of which represents the North America plate. Forcing is by assigned subduction pull, and tractions at all plate boundaries satisfy a viscous constitutive law. Plate bottoms are stress-free. In the first part of the solution plate velocities and boundary tractions are found from static equilibrium. Then principal horizontal stresses and strains in plate interiors caused by tractions and subduction pull are found by a boundary element procedure. Using plate boundary geometry from Stock and Hodges for early- and mid-Miocene times, it is found that the portion of the North America plate margin between the Mendocino and Rivera triple junctions has maximum extensional strain directed westward. This result is generally consistent with directions associated with metamorphic core complex formation in southern California. The model is also consistent with extensional strain and rotation sense of crustal blocks in the vicinity of Los Angeles, as inferred by Luyendyk and others from paleomagnetic data. In the model the greatest extensional strain of the North America plate occurs near the Pacific-North America transform, in the area above the absent Farallon slab. Extension direction varies from northwest to southwest according to plate geometry, subduction pull (Juan de Fuca and Guadalupe), and plate boundary tractions.

  4. Scope and construction of a gas and oil atlas series of the Gulf of Mexico: Examples from Texas offshore lower Miocene plays

    SciTech Connect

    Seni, S.J.; Desselle, B.A.; Standen, A. [Univ. of Texas, Austin, TX (United States)

    1994-12-31

    An atlas series about the offshore northern Gulf of Mexico will group gas and oil reservoirs into subregional plays and will display reservoir data on a computerized geographical information system. The atlas series will provide critically compiled reservoir engineering data to help the private sector explore and develop hydrocarbons and to help the public sector analyze the hydrocarbon endowment in this basin. In this report, we cover aspects of the play-analysis procedure and provide specific examples of lower Miocene plays from the upper Texas coast and Federal Outer Continental Shelf (OCS). Play analysis emphasizes using broad classes of structural style, depositional style and environments, and defining attributes to group reservoirs into plays. To date, we have identified 4 Oligocene and 25 Miocene plays in Texas State offshore waters and 115 plays in the Federal OCS. Texas State offshore plays are gas prone (cumulative production 3.7 TcF) and are preferentially trapped in rollover anticlines. Miocene plays include submarine-fan Lenticulina sandstones; progradational Dicorbis b., Siphonina d., Marginulina a., and Lenticulina sandstones; transgressive sandstones associated with a barrier-bar system in the Matagorda Area; and transgressive Amphistegina B sandstones. Particularly productive gas-prone plays are progradational Sihonina d. deltas in the High Island Area and progradational Marginulia a. shelf and deltaic sandstones in the Matagorda Island and Brazos Areas.

  5. Millennial scale climatic responses through a Late Miocene precession cycle

    NASA Astrophysics Data System (ADS)

    Marzocchi, Alice; Lunt, Dan; Flecker, Rachel; Bradshaw, Catherine

    2014-05-01

    Late Miocene (11.61-5.33 Ma) climate is thought to have been warmer and wetter than the present, with nearly ice-free conditions over the Northern Hemisphere, and significant differences in vegetation distribution. There still is considerable uncertainty in the reconstructed CO2 levels for this time period, fostered by the temporally and spatially biased distribution of the available proxy record. Previous model-data comparison studies (i.e. Bradshaw et al., 2012; Pound et al., 2011) highlighted the mismatch between model results and proxy data for this time period. Here, we investigate how taking into account the variability due to changes in orbital forcing can account for some of these differences. We also explore the orbital control on the monsoonal systems at millennial scale resolution, as well as the impact of background CO2 on orbital sensitivity. Long-term changes in seasonal and latitudinal solar insolation are generated by periodic oscillations in the Earth's orbit and tilt relative to the Sun. These cycles have a modulating effect on climate and ocean circulation patterns. A record of this signal can be found in a number of terrestrial and marine sedimentary sequences. A series of 22 fully coupled atmosphere-ocean-vegetation simulations has been run through an entire precession cycle during the Late Miocene (~6.5 Ma). These experiments were performed using HadCM3L (Hadley Centre Coupled Model, Version 3 - Low resolution ocean) with TRIFFID (Top-down Representation of Interactive Foliage and Flora Including Dynamics) to test the climatic response to changes in orbital forcing. The Mediterranean Sea provides a remarkable geological record for this time slice. Several sequences around the basin margins have been astronomically tuned so that high resolution geological data can be directly compared with our model results. However, this is not the case for the rest of the world, where the distribution of climate proxy data for the Late Miocene is sparse, patchy and is typically constrained by a low-resolution age model. Model results show the effect of different orbital configurations on the North African summer monsoon, with highly intensified precipitation patterns over these regions at times of minimum precession (maximum insolation), triggering significant changes in vegetation belts. Our simulations are compared quantitatively with the palaeorecord and show that orbital forcing could explain some, but not all, of the published model-data mismatch. Bradshaw, C. D., Lunt, D. J., Flecker, R., Salzmann, U., Pound, M. J., Haywood, A. M., and Eronen, J. T.: The relative roles of CO2 and palaeogeography in determining late Miocene climate: results from a terrestrial model-data comparison, Clim. Past, 8, 1257-1285, 2012. Pound, M. J., Haywood, A. M., Salzmann, U., Riding, J. B., Lunt, D. J., and Hunter, S. J.: A Tortonian (late Miocene, 11.61-7.25 Ma) global vegetation reconstruction, Palaeogeogr. Palaeocl., 300, 29-45, 2011.

  6. Tropical sea surface temperature variability near the Oligocene - Miocene boundary

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Pagani, M.

    2010-12-01

    The Oligocene/Miocene (O-M) boundary is characterized by a period of rapid and intense glaciation labeled Mi-1 at ~ 23.1 Ma. An abrupt 1.5‰ increase in the benthic foraminifera oxygen isotope composition that characterizes Mi-1 may indicate a (1) significant deep-water temperature decrease; (2) major ice-sheet expansion, or the combination of both. Current coarse Mg/Ca-based temperature estimations for the early Miocene suggests that deep-ocean temperatures were ~2°C warmer than Today [1, 2]. However, Mg/Ca based temperatures can also be influenced by changes in the carbonate ion concentration, vital effects, and diagenesis. In particular, recent evidence from mid-ocean ridge flank carbonate veins shows dramatic seawater Mg/Ca ratio changes during the Neogene (Mg/Ca from ~2.2 to 5.3, [3]), which further challenges the application of Mg/Ca thermometry. Owing to poor temperature constraints, current ice volume estimations for the late Oligocene/early Miocene range from 125% of the present-day East Antarctic Ice Sheet (EAIS) to a nearly complete collapse of the Antarctic glaciers [4]. Here we present tropical sea surface temperatures (SSTs) records based on TEX86 and alkenone UK37 near the O-M boundary. Sediment samples from Ocean Drilling Program (ODP) Site 926 in the Ceara Rise (tropical Atlantic) and Site 1148 in the South China Sea (tropical Pacific) were subject to lipid extraction, separation, gas chromatography, and liquid chromatography-mass spectrometry analysis. TEX86-based SST indicates that the tropics were ~3-4°C warmer than today and relatively stable during Mi-1. This suggests that ice-sheet dynamics, rather than temperature, might be responsible for the observed oxygen isotope changes during the O-M boundary. Further, O-M boundary averaged temperatures recorded at site 926 is ~ 0.5°C higher relative to the late Eocene from site 925 (a nearby site [5]). Given late Oligocene benthic ?18O that suggests at least 1‰ enrichment relative to the late Eocene (e.g. ODP 1218 [2]), our records suggest major Antarctic ice build-up in the Oligocene. Additional work across high-latitude sites is necessary to evaluate how the extratropics responded to climate change during Mi-1, as well as modeling efforts to quantitatively resolve ice volume from temperature. [1] K. Billups, D.P. Schrag, Paleotemperatures and ice volume of the past 27 Myr revisited with paired Mg/Ca and 18O/16O measurements on bethic foraminifera, Paleoceanography 17(2002). [2] C.H. Lear, Y. Rosenthal, H.K. Coxall, P.A. Wilson, Late Eocene to early Miocene ice sheet dynamics and the global carbon cycle, Paleoceanography 19(2004). [3] R.M. Coggon, D.A.H. Teagle, C.E. Smith-Duque, J.C. Alt, M.J. Copper, Reconstructing past seawater Mg/Ca and Sr/Ca from Mid-Ocean Ridge flank calcium carbonate veins, Science 327(2010) 1141-1147. [4] S.F. Pekar, R.M. DeConto, High-resolution ice-volume estimates for the early Miocene: Evidence for a dynamic ice sheet in Antarctica, Palaeogeogr. Palaeoclimatol. Palaeoecol. 231(2006) 101-109. [5] Z. Liu, M. Pagani, D. Zinniker, R. DeConto, M. Huber, H. Brinkhuis, S.R. Shah, R.M. Leckie, A. Pearson, Global Cooling During the Eocene-Oligocene Climate Transition, Science 323(2009) 1187-1190.

  7. Biostratigraphic sequence analysis of two Lower Miocene to Pliocene sections, Eastern Falcon, Northwestern Venezuela

    SciTech Connect

    Diaz De Gamero, M.L. (Universidad Central de Venezuela, Caracus (Venezuela)); Giffuni, G.; Castro Mora, M. (Lagoven S.A., Caracus (Venezuela))

    1993-02-01

    The eastern region of the Falcon Basin in northwestern Venezuela comprises a thick sedimentary sequence deposited from a deep marine bathyal to neritic environment, ranging in age from the Middle Eocene to the Pliocene. A detailed biostratigraphic study (foraminifera and calcareous nannoplankton) was carried out in two sedimentary sequences outcropping in Cumarebo and Piritu, adjacent areas of eastern Falcon, representing: platform, slope and basinal settings. The Cumarebo section is continuous in the studied interval, from the Middle Miocene to the Pliocene. The Piritu section is continuous from the Lower to the lower Upper Miocene, terminating unconformably beneath a thin interval of middle Pliocene platform sediments, indicating tectonism during the latest Miocene. The sequence stratigraphical interpretation was based on the biostratigraphic analysis of the benthic and planktonic fossils, facies distribution and sedimentological data. Systems tracts, sequence boundaries and maximum flooding surfaces from cycles TB2.4 to TB3.5 of the cycle chart were identified. In the Cumarebo section, the upper Middle and Upper Miocene is mostly composed of shales, with some turbiditic sands belonging to a LSW system tract. The upper most Miocene contains a thick carbonate buildup (HST), and it is overlain by a Pliocene section that shallows upward from upper slope to outer shelf depositional environments. In the basinal (Piritu) section, most of the sediments are deep-water shales belonging to a LSW system tract, with some turbiditic sands in the upper Lower Miocene. TST and HST sediments, with scattered carbonate buildups in the upper Middle Miocene were also identified.

  8. Paleosols and paleoenvironments of the middle Miocene, Maboko Formation, Kenya.

    PubMed

    Retallack, Gregory J; Wynn, Jonathan G; Benefit, Brenda R; Mccrossin, Monte L

    2002-06-01

    The middle Miocene (15 Ma) Maboko Formation of Maboko Island and Majiwa Bluffs, southwestern Kenya, has yielded abundant fossils of the earliest known cercopithecoid monkey (Victoriapithecus macinnesi), and of a kenyapithecine hominoid (Kenyapithecus africanus), as well as rare proconsuline (Simiolus leakeyorum, cf. Limnopithecus evansi) and oreopithecine apes (Mabokopithecus clarki, M. pickfordi), and galagids (Komba winamensis). Specific habitat preferences can be interpreted from large collections of primate fossils in different kinds of paleosols (pedotypes). Fossiliferous drab-colored paleosols with iron-manganese nodules (Yom pedotype) are like modern soils of seasonally waterlogged depressions (dambo). Their crumb structure and abundant fine root-traces, as well as scattered large calcareous rhizoconcretions indicate former vegetation of seasonally wet, wooded grassland. Other fossiliferous paleosols are evidence of nyika bushland (Ratong), and early-successional riparian woodland (Dhero). No fossils were found in Mogo paleosols interpreted as saline scrub soils. Very shallow calcic horizons (in Yom, Ratong, and Mogo paleosols) and Na-montmorillonite (in Mogo) are evidence of dry paleoclimate (300-500 mm MAP=mean annual precipitation). This is the driest paleoclimate and most open vegetation yet inferred as a habitat for any Kenyan Miocene apes or monkeys. Victoriapithecus was abundant in dambo wooded grassland (Yom) and riparian woodland (Dhero), a distribution like that of modern vervet monkeys. Kenyapithecus ranged through all these paleosols, but was the most common primate in nyika bushland paleosols (Ratong), comparable to baboons and macaques today. Mabokopithecus was virtually restricted to riparian woodland paleosols (Dhero), and Simiolus had a similar, but marginally wider, distribution. Habitat preferences of Mabokopithecus and Simiolus were like those of modern colobus monkeys and mangabeys. A single specimen of Komba was found in dambo wooded grassland paleosol (Yom), a habitat more like that of the living Senegal bushbaby than of rainforest galagids. A shift to non-forest habitats may explain the terrestrial adaptations of Victoriapithecus, basal to the cercopithecid radiation, and of Kenyapithecus, basal to the hominoid radiation. Both taxa are distinct from earlier Miocene arboreal proconsulines, oreopithecines and galagids. PMID:12069506

  9. Extent of underthrusting of the Indian plate beneath Tibet controlled the distribution of Miocene porphyry Cu-Mo ± Au deposits

    NASA Astrophysics Data System (ADS)

    Wang, Rui; Richards, Jeremy P.; Hou, Zengqian; Yang, Zhiming

    2014-02-01

    Miocene igneous rocks in the 1,600 km-long E-W Gangdese belt of southern Tibet form two groups separated at longitude ˜89° E. The eastern group is characterized by mainly intermediate-felsic calc-alkaline plutons with relatively high Sr/Y ratios (23 to 342), low (87Sr/86Sr)i ratios (0.705 to 0.708), and high ?Ndi values (+5.5 to -6.1). In contrast, the western group is characterized by mainly potassic to ultrapotassic volcanic rocks with relatively high Th and K2O contents, low Sr/Y ratios (11 to 163), high (87Sr/86Sr)i ratios (0.707 to 0.740), and low ?Ndi values (-4.1 to -17.5). The eastern plutonic group is associated with several large porphyry Cu-Mo ± Au deposits, whereas the western group is largely barren. We propose that the sharp longitudinal distinction between magmatism and metallogenic potential in the Miocene Gangdese belt reflects the breakoff of the Greater India slab and the extent of underthrusting by the Indian continental lithosphere at that time. Magmas to the east of ˜89° E were derived by partial melting of subduction-modified Tibetan lithosphere (mostly lower crust) triggered by heating of hot asthenospheric melt following slab breakoff. These magmas remobilized metals and volatile residual in the crustal roots from prior arc magmatism and generated porphyry Cu-Mo ± Au deposits upon emplacement in the upper crust. In contrast, magmas to the west of ˜89° E were formed by smaller volume partial melting of Tibetan lithospheric mantle metasomatized by fluids and melts released from the underthrust Indian plate. They are less hydrous and oxidized and did not have the capacity to transport significant amounts of metals into the upper crust.

  10. A near-infrared reflectance spectroscopy method for direct analysis of several chemical components and properties of fruit, for example, Chinese hawthorn.

    PubMed

    Dong, Wenjiang; Ni, Yongnian; Kokot, Serge

    2013-01-23

    Near-infrared spectroscopy (NIRS) calibrations were developed for the discrimination of Chinese hawthorn (Crataegus pinnatifida Bge. var. major) fruit from three geographical regions as well as for the estimation of the total sugar, total acid, total phenolic content, and total antioxidant activity. Principal component analysis (PCA) was used for the discrimination of the fruit on the basis of their geographical origin. Three pattern recognition methods, linear discriminant analysis, partial least-squares-discriminant analysis, and back-propagation artificial neural networks, were applied to classify and compare these samples. Furthermore, three multivariate calibration models based on the first derivative NIR spectroscopy, partial least-squares regression, back-propagation artificial neural networks, and least-squares-support vector machines, were constructed for quantitative analysis of the four analytes, total sugar, total acid, total phenolic content, and total antioxidant activity, and validated by prediction data sets. PMID:23265446

  11. A partial hominoid innominate from the Miocene of Pakistan: description and preliminary analyses.

    PubMed

    Morgan, Michèle E; Lewton, Kristi L; Kelley, Jay; Otárola-Castillo, Erik; Barry, John C; Flynn, Lawrence J; Pilbeam, David

    2015-01-01

    We describe a partial innominate, YGSP 41216, from a 12.3 Ma locality in the Siwalik Group of the Potwar Plateau in Pakistan, assigned to the Middle Miocene ape species Sivapithecus indicus. We investigate the implications of its morphology for reconstructing positional behavior of this ape. Postcranial anatomy of extant catarrhines falls into two distinct groups, particularly for torso shape. To an extent this reflects different although variable and overlapping positional repertoires: pronograde quadrupedalism for cercopithecoids and orthogrady for hominoids. The YGSP innominate (hipbone) is from a primate with a narrow torso, resembling most extant monkeys and differing from the broader torsos of extant apes. Other postcranial material of S. indicus and its younger and similar congener Sivapithecus sivalensis also supports reconstruction of a hominoid with a positional repertoire more similar to the pronograde quadrupedal patterns of most monkeys than to the orthograde patterns of apes. However, Sivapithecus postcranial morphology differs in many details from any extant species. We reconstruct a slow-moving, deliberate, arboreal animal, primarily traveling above supports but also frequently engaging in antipronograde behaviors. There are no obvious synapomorphic postcranial features shared exclusively with any extant crown hominid, including Pongo. PMID:25489095

  12. Herds Overhead: Nimbadon lavarackorum (Diprotodontidae), Heavyweight Marsupial Herbivores in the Miocene Forests of Australia

    PubMed Central

    Black, Karen H.; Camens, Aaron B.; Archer, Michael; Hand, Suzanne J.

    2012-01-01

    The marsupial family Diprotodontidae (Diprotodontia, Vombatiformes) is a group of extinct large-bodied (60–2500 kg) wombat-like herbivores that were common and geographically widespread in Cenozoic fossil deposits of Australia and New Guinea. Typically they are regarded to be gregarious, terrestrial quadrupeds and have been likened in body form among placental groups to sheep, rhinoceros and hippopotami. Arguably, one of the best represented species is the zygomaturine diprotodontid Nimbadon lavarackorum which is known from exceptionally well-preserved cranial and postcranial material from the middle Miocene cave deposit AL90, in the Riversleigh World Heritage Area, northwestern Queensland. Here we describe and functionally analyse the appendicular skeleton of Nimbadon lavarackorum and reveal a far more unique lifestyle for this plesiomorphic and smallest of diprotodontids. Striking similarities are evident between the skeleton of Nimbadon and that of the extant arboreal koala Phascolarctos cinereus, including the powerfully built forelimbs, highly mobile shoulder and elbow joints, proportionately large manus and pes (both with a semi-opposable digit I) and exceedingly large, recurved and laterally compressed claws. Combined with the unique (among australidelphians) proportionately shortened hindlimbs of Nimbadon, these features suggest adept climbing ability, probable suspensory behaviour, and an arboreal lifestyle. At approximately 70 kg, Nimbadon is the largest herbivorous mammal to have occupied the forest canopies of Australia - an ecological niche that is no longer occupied in any Australian ecosystem and one that further expands the already significant niche diversity displayed by marsupials during the Cenozoic. PMID:23185250

  13. A new genus of the family Jaculinidae (Cheilostomata, Bryozoa) from the Miocene of the tropical western Atlantic.

    PubMed

    Zágoršek, Kamil; Ramalho, Laís V; Berning, Björn; De Araújo Távora, Vladimir

    2014-01-01

    Pirabasoporella gen. nov. is introduced for three new bryozoan species from the Early Miocene of the tropical western Atlantic. The genus is placed in the family Jaculinidae Zabala, a peculiar group of cheilostome bryozoans characterised by reticulate colonies formed by uni- or biserial branches that are connected by kenozooidal struts. This colonial morphology superficially resembles colonies of the Paleozoic order Fenestrata (Stenolaemata) and some Recent Cyclostomata. As jaculinid colonies are anchored to soft sediments via rhizoids, however, they differ in life habit from Paleozoic and modern fenestrate colonies, which are firmly attached to stable substrata by an encrusting base.        The three new species are Pirabasoporella atalaiaensis n. sp. from the Brazilian Pirabas Formation, Pirabasoporella baitoae n. sp. from the Baitoa Formation (Dominican Republic), and Pirabasoporella chipolae n. sp. from the Floridan Chipola Formation. Their presence in the Early Miocene western Atlantic represents the earliest record of Jaculinidae, and suggests that the origin of the family, the only living species of which are known from the eastern Atlantic and Mediterranean Sea, extends well into the Paleogene.        The Jaculinidae is here transferred from the lepraliomorph superfamily Schizoporelloidea Jullien to the umbonulomorph Lepralielloidea Vigneaux owing to the partly umbonuloid frontal shield and non-schizoporelloid ovicell. PMID:25081761

  14. A new Middle Miocene tarsier from Thailand and the reconstruction of its orbital morphology using a geometric–morphometric method

    PubMed Central

    Chaimanee, Yaowalak; Lebrun, Renaud; Yamee, Chotima; Jaeger, Jean-Jacques

    2011-01-01

    Tarsius is an extant genus of primates endemic to the islands of Southeast Asia that is characterized by enormously enlarged orbits reflecting its nocturnal activity pattern. Tarsiers play a pivotal role in reconstructing primate phylogeny, because they appear to comprise, along with Anthropoidea, one of only two extant haplorhine clades. Their fossils are extremely rare. Here, we describe a new species of Tarsius from the Middle Miocene of Thailand. We reconstructed aspects of its orbital morphology using a geometric–morphometric method. The result shows that the new species of Tarsius had a very large orbit (falling within the range of variation of modern Tarsius) with a high degree of frontation and a low degree of convergence. Its relatively divergent lower premolar roots suggest a longer mesial tooth row and therefore a longer muzzle than in extant species. The new species documents a previous unknown Miocene group of Tarsius, indicating greater taxonomic diversity and morphological complexity during tarsier evolution. The current restriction of tarsiers to offshore islands in Southeast Asia appears to be a relatively recent phenomenon. PMID:21123264

  15. Late Miocene lineage divergence and ecological differentiation of rare endemic Juniperus blancoi: clues for the diversification of North American conifers.

    PubMed

    Moreno-Letelier, Alejandra; Mastretta-Yanes, Alicia; Barraclough, Timothy G

    2014-07-01

    Western North America and Mexico contain a large number of conifer species. This diversity could be the product of orographic and climate changes of the late Tertiary and Quaternary. In this study, we focus on the evolutionary history of Juniperus blancoi, in order to determine the impact of climate change and environmental heterogeneity on population differentiation. We estimated the population structure, phylogenetic relationships and historical demography of J. blancoi populations using nuclear genes. We correlated genetic structure with ecological differentiation, divergence times and changes in population size. Populations of J. blancoi are differentiated into three lineages that correspond to low-, mid- and high-altitude populations. The three groups diversified in the late Miocene, early Pliocene, with only a few events of gene flow since then. Two lineages in the north exhibited a pattern of population growth during the Pleistocene that could be linked to climate changes. Populations of J. blancoi experienced significant ecological differentiation and early divergence events, which correspond to periods of global cooling and mountain uplift during the Miocene. This suggests that mountain ranges in tropical and subtropical latitudes play an important role in the speciation and persistence of conifer taxa in diversity hotspots, by providing diverse environmental conditions. PMID:24611638

  16. Ruminant diets and the Miocene extinction of European great apes

    PubMed Central

    Merceron, Gildas; Kaiser, Thomas M.; Kostopoulos, Dimitris S.; Schulz, Ellen

    2010-01-01

    The successful evolutionary radiations of European hominoids and pliopithecoids came to an end during the Late Miocene. Using ruminant diets as environmental proxies, it becomes possible to detect variations in vegetation over time with the potential to explain fluctuations in primate diversity along a NW–SE European transect. Analysis shows that ruminants had diverse diets when primate diversity reached its peak, with more grazers in eastern Europe and more browsers farther west. After the drop in primate diversity, grazers accounted for a greater part of western and central European communities. Eastwards, the converse trend was evident with more browsing ruminants. These opposite trends indicate habitat loss and an increase in environmental uniformity that may have severely favoured the decline of primate diversity. PMID:20519220

  17. Gulf of Mexico Miocene CO? Site Characterization Mega Transect

    SciTech Connect

    Meckel, Timothy; Trevino, Ramon

    2014-09-30

    This project characterized the Miocene-age sub-seafloor stratigraphy in the near-offshore portion of the Gulf of Mexico adjacent to the Texas coast. The large number of industrial sources of carbon dioxide (CO2) in coastal counties and the high density of onshore urbanization and environmentally sensitive areas make this offshore region extremely attractive for long-term storage of carbon dioxide emissions from industrial sources (CCS). The study leverages dense existing geologic data from decades of hydrocarbon exploration in and around the study area to characterize the regional geology for suitability and storage capacity. Primary products of the study include: regional static storage capacity estimates, sequestration “leads” and prospects with associated dynamic capacity estimates, experimental studies of CO2-brine-rock interaction, best practices for site characterization, a large-format ‘Atlas’ of sequestration for the study area, and characterization of potential fluid migration pathways for reducing storage risks utilizing novel high-resolution 3D (HR3D) seismic surveys. In addition, three subcontracted studies address source-to-sink matching optimization, offshore well bore management and environmental aspects. The various geologic data and interpretations are integrated and summarized in a series of cross-sections and maps, which represent a primary resource for any near-term commercial deployment of CCS in the area. The regional study characterized and mapped important geologic features (e.g., Clemente-Tomas fault zone, the regionally extensive Marginulina A and Amphistegina B confining systems, etc.) that provided an important context for regional static capacity estimates and specific sequestration prospects of the study. A static capacity estimate of the majority of the Study area (14,467 mi2) was estimated at 86 metric Gigatonnes. While local capacity estimates are likely to be lower due to reservoir-scale characteristics, the offshore Miocene interval is a storage resource of National interest for providing CO2 storage as an atmospheric emissions abatement strategy. The natural petroleum system was used as an analog to infer seal quality and predict possible migration pathways of fluids in an engineered system of anthropogenic CO2 injection and storage. The regional structural features (e.g., Clemente-Tomas fault zone) that exert primary control on the trapping and distribution of Miocene hydrocarbons are expected to perform similarly for CCS. Industrial?scale CCS will require storage capacity utilizing well?documented Miocene hydrocarbon (dominantly depleted gas) fields and their larger structural closures, as well as barren (unproductive, brine?filled) closures. No assessment was made of potential for CO2 utilization for enhanced oil and gas recovery. The use of 3D numerical fluid flow simulations have been used in the study to greatly assist in characterizing the potential storage capacity of a specific reservoir. Due to the complexity of geologic systems (stratigraphic heterogeneity) and inherent limitations on producing a 3D geologic model, these simulations are typically simplified scenarios that explore the influence of model property variability (sensitivity study). A specific site offshore San Luis Pass (southern Galveston Island) was undertaken successfully, indicating stacked storage potential. Downscaling regional capacity estimates to the local scale (and the inverse) has proven challenging, and remains an outstanding gap in capacity assessments. In order to characterize regional seal performance and identify potential brine and CO2 leakage pathways, results from three high-resolution 3D (HR3D) seismic datasets acquired by the study using novel HR3D (P-Cable) acquisition system showed steady and significant improvements in data quality because of improved acquisition and processing technique. Finely detailed faults and stratigraphy in the shallowest 1000 milliseconds (~800 m) of data allowed for the identification and mapping of unconformable surfaces including what is probably

  18. A Miocene submarine volcano at Low Layton, Jamaica

    NASA Technical Reports Server (NTRS)

    Wadge, G.

    1982-01-01

    A submarine fissure eruption of Upper Miocene age produced a modest volume of alkaline basalt at Low Layton, on the north coast of Jamaica. The eruption occurred in no more than a few hundred meters of water and produced a series of hyaloclastites, pillow breccias and pillow lavas, massive lavas, and dikes with an ENE en echelon structure. The volcano lies on the trend of one of the island's major E-W strike-slip fault zones; the Dunavale Fault Zone. The K-Ar age of the eruption of 9.5 plus or minus 0.5 Ma. B.P. corresponds to an extension of the Mid-Cayman Rise spreading center inferred from magnetic anomalies and bathymetry of the Cayman Trough to the north and west of Jamaica. The Low Layton eruption was part of the response of the strike-slip fault systems adjacent to this spreading center during this brief episode of tectonic readjustment.

  19. Changing seasonality patterns in Central Europe from Miocene Climate Optimum to Miocene Climate Transition deduced from the Crassostrea isotope archive

    NASA Astrophysics Data System (ADS)

    Harzhauser, Mathias; Piller, Werner E.; Müllegger, Stefan; Grunert, Patrick; Micheels, Arne

    2011-03-01

    The Western Tethyan estuarine oyster Crassostrea gryphoides is an excellent climate archive due to its large size and rapid growth. It is geologically long lived and allows a stable isotope-based insight into climatic trends during the Miocene. Herein we utilised the climate archive of 5 oyster shells from the Miocene Climate Optimum (MCO) and the subsequent Miocene Climate Transition (MCT) to evaluate changes of seasonality patterns. MCO shells exhibit highly regular seasonal rhythms of warm-wet and dry-cool seasons. Optimal conditions resulted in extraordinary growth rates of the oysters. ? 13C profiles are in phase with ? 18O although phytoplankton blooms may cause a slight offset. Estuarine waters during the MCO in Central Europe display a seasonal temperature range of c. 9-10 °C. Absolute water temperatures have ranged from 17 to 19 °C during cool seasons and up to 28 °C in warm seasons. Already during the early phase of the MCO, the growth rates are distinctly declining, although gigantic and extremely old shells have been formed at that time. Still, a very regular and well expressed seasonality is dominating the isotope profiles, but episodically occurring extreme climate events influence the environments. The seasonal temperature range is still c. 9 °C but the cool season temperature seems to be slightly lower (16 °C) and the warm season water temperature does not exceed c. 25 °C. In the later MCT at c. 12.5-12.0 Ma the seasonality pattern is breaking down and is replaced by successions of dry years with irregular precipitation events. No correlation between ? 18O and ? 13C is documented maybe due to a suboptimal nutrition level which would explain the low growth rates and small sizes. The amplitude of seasonal temperature range is decreasing to 5-8 °C. No clear cooling trend can be postulated for that time as the winter season water temperatures range from 15 to 20 °C. This may point to unstable precipitation rhythms on a multi-annual to decadal scale as main difference between MCO and MCT climates in Central Europe instead of a simple temperature decline scenario.

  20. Oligo-Miocene foraminiferal record (Miogypsinidae, Lepidocyclinidae and Nummulitidae) from the Western Taurides (SW Turkey): Biometry and implications for the regional geology

    NASA Astrophysics Data System (ADS)

    Özcan, Ercan; Less, György; Báldi-Beke, Mária; Kollányi, Katalin; Acar, Ferhat

    2009-05-01

    The marine Oligo-Miocene units of western Taurides, deposited under different tectonic regimes (in Bey Da?lar? platform in foreland and coeval sequences in hinterland), were studied to establish a high-resolution biostratigraphic framework. Biometric study of the full spectrum of larger foraminifera in a regional scale allowed us correlating them with the shallow benthic zonation (SBZ) system introduced by [Cahuzac, B., Poignant, A., 1997. Essai de biozonation de l'Oligo-Miocène dans les bassins européens à l'aide des grands foraminifères néritiques. Bulletin de la Société géologique de France 168, 155-169], and to determine the ages of these sites on zonal precision for the first time. In correlating these assemblages to standard shallow benthic zones, planktonic data were also used whenever possible. Taxa, classified under the genera Nummulites, Miogypsina, Miolepidocyclina, Nephrolepidina, Eulepidina, Heterostegina, Operculina and Cycloclypeus (?) and their assemblages, closely resemble to the fauna described from European basins. These groups characterize the SBZ 22B to 25 zones referring to a time interval from early Chattian to Burdigalian. However, a main gap in late Chattian (SBZ 23) and in early part of the Aquitanian (SBZ 24) is also recorded in the platform succession. In the meantime, rare Eulepidina in the Burdigalian levels suggest a clear Indo-Pacific influence. Based on the discovery of early Chattian (SBZ 22B) deposits (previously mapped under Eocene/Miocene units), the Oligo-Miocene stratigraphy of the Bey Da?lar? platform is also revised. A more precise chronology for regional Miocene transgression is presented based on the miogypsinid evolutionary scale.

  1. Miocene honey bees from the Randeck Maar of southwestern Germany (Hymenoptera, Apidae)

    E-print Network

    Ulrich, Kotthoff; Wappler, Torsten; Engel, Michael S.

    2011-03-10

    The Miocene Randeck Maar (southwestern Germany) is one of the only sites with abundant material of fossil honey bees. The fauna has been the focus of much scrutiny by early authors who recognized multiple species or subspecies within the fauna...

  2. A new termite bug in Miocene amber from the Dominican Republic (Hemiptera, Termitaphididae)

    E-print Network

    Engel, Michael S.

    2009-10-23

    A new species of the termite bug genus Termitaradus Myers (Aradoidea: Termitaphididae) is described and figured based on a single female preserved in Early Miocene (Burdigalian) amber from the Dominican Republic. Termitaradus mitnicki sp. n. differs...

  3. Waning Miocene subduction and arc volcanism in Baja California: the San Luis Gonzaga volcanic field

    NASA Astrophysics Data System (ADS)

    Martín, Arturo; Fletcher, John M.; López-Martínez, Margarita; Mendoza-Borunda, Ramón

    2000-03-01

    Subduction of the Guadalupe-Magdalena microplate beneath Baja California ended in the middle Miocene, and the last volcanic events in the frontal arc extinguished along the present-day eastern margin of the Baja California peninsula. The San Luis Gonzaga area in the north-central Gulf coast contains one of the younger arc-related volcanic centers in northern Baja California. The volcanic succession contains three sequences. The basal sequence (Group 1) is composed of stratified pyroclastic deposits, up to 500 m thick, and subordinate lava flows. The near-vent facies crop out in tilted fault blocks along the present shoreline, whereas the distal facies are exposed across ˜12 km toward the west and includes epiclastic deposits and at least three ash flow tuffs. This sequence is internally concordant and overlies smooth paleosurface developed on granitic basement, and pinches out across the Gulf escarpment. The Potrero Andesite (Group 2) is a series of dacite to basaltic-andesite lava flows from a shield volcano located ˜15 km west of today's coastline; similar source vents also occurs further south of the San Luis Gonzaga area. A sequence of dacite domes (Group 3) intrudes the near-vent facies of Group 1 and contains subordinate volcanic breccia and minor lava flows that overlie Group 1 sequence. Cross-cutting relationships and the abundance of volcanic breccia associated with the domes suggest that these domes were emplaced as semi-rigid intrusions (spines) with low explosive activity. The San Luis Gonzaga volcanic suite ranges in composition from basaltic andesite to dacite with predominant plagioclase and pyroxene and variable amounts of hornblende. Trace-element patterns indicate calc-alkaline to mildly alkaline magmas with high Ba and low Nb contents. Incompatible-element ratios and mineralogical characteristics suggest different magma batches and/or different amount of crustal assimilation for the three sequences that produced contrasting eruptive styles. A pink dacitic tuff that lies in the upper portion of Group 1 yielded an 40Ar/ 39Ar age of 17.2±0.3 Ma. The most precise of three ages from the andesitic sheet flows of Group 2 is 15.4±0.5 Ma. The dacite domes of Group 3 represent the end of Miocene arc activity, but they are strongly altered and no reliable ages were obtained. These data fall within the range of isotopic ages reported for arc lavas (21 to 16 Ma) from the discontinuous series of isolated volcanic fields in northern Baja California. This contrasts with the continuous and more voluminous arc-volcanism in southern Baja California that started earlier (25 Ma) and ended later (11 Ma). These space-time patterns of arc volcanism reflect the geometry of the subducted Farallon slab and the history of its breakup as the Rivera triple junction migrated to the south.

  4. Widespread Miocene deep-sea hiatuses: coincidence with periods of global cooling.

    USGS Publications Warehouse

    Barron, J.A.; Keller, G.

    1982-01-01

    High-resolution biostratigraphic analyses of Miocene deep-sea cores reveal eight intervals of widespread hiatuses in the world ocean. In complete sections these hiatuses correspond to intervals of cool faunal and floral assemblages, rapid enrichment of delta 18O, and sea-level regressions. These factors suggest that Miocene deep-sea hiatuses result from an increased intensity of circulation and corrosiveness of bottom currents during periods of increased polar refrigeration.-Authors

  5. Deformation of the late Miocene to Pliocene Inyo Surface, eastern Sierra region, California

    USGS Publications Warehouse

    Jayko, A.S.

    2009-01-01

    A middle and late Miocene erosion surface, the Inyo Surface, underlies late Miocene mafic flows in the White Mountains and late Miocene and (or) early Pliocene flows elsewhere in the eastern Sierra region. The Inyo Surface is correlated with an erosion surface that underlies late Miocene mafic flows in the central and northern Sierra Nevada. The mafic flows had outpourings similar to flood basalts, although of smaller volume, providing paleohorizontal and paleolowland indicators. The flows filed and locally topped the existing landscape forming broad plateau-like flats. Topographic relief in the region was characterized by weathered and rounded slopesp rior to late Miocene mafic magmatism. Relicts of the older landscape lie adjacent to late Miocene and early Pliocene basalt-covered lowlands that now occur within the crests of ranges that have 2500-3000 m relief and dramatically steep escarpments. Late Miocene mafic flows that lie on the crest of the Sierra Nevada adjacent to the White Mountains predate significant activity on the Sierra Nevada frontal fault zone. These deposits and accompanying erosion surfaces provide excellent strain markers for reconstructing part of the Walker Lane north of the Garlock fault and west of the Amargosa drainage, here referred to as the eastern Sierra region. The Inyo Surface is a compound erosional surface that records at least four major erosion events during the Cenozoic. These four surfaces were first recognized on the Kern Plateau and named from oldest to youngest, the Summit Upland, the Subsummit Plateau, the Chagoopa Plateau, and the Canyon. The three older surfaces have also been subsequently modifi ed by Pleistocene glaciation. The compound erosion surface, which is locally overlain by late Miocene mafic flows in the northern and central Sierra Nevada, is here referred to as the Lindgren Surface. Correlatives in the eastern Sierra region are found in the White Mountains, Inyo Mountains, Darwin Plateau, Coso Range, and nearby ranges. Copyright ?? 2009 The Geological Society of America.

  6. Variations in the strontium isotopic ratio of seawater during the Miocene: Stratigraphic and geochemical implications

    Microsoft Academic Search

    David A. Hodell; Fay Woodruff

    1994-01-01

    A composite strontium isotopic seawater curve was constructed for the Miocene between 24 and 6 Ma by combining 87Sr\\/86Sr measurements of planktonic foraminifera from Deep Sea Drilling Project sites 289 and 588. Site 289, with its virtually continuous sedimentary record and high sedimentation rates (26 m\\/m.y.), was used for constructing the Oligocene to mid-Miocene part of the record, which included

  7. Depositional and structural evolution of the Middle Miocene depositional episode, east-central Gulf of Mexico

    Microsoft Academic Search

    Ricardo Ignacio Combellas Bigott

    2003-01-01

    Two widespread, transgressive deposits associated with the faunal top Amphistegina B (15.5 Ma) and Textularia W (12.1 Ma) define the Middle Miocene depositional episode. An extensive stratigraphic correlation framework established in this study allowed tracing of the middle Miocene sediment dispersal system from the shelf through the slope to the basin floor in the complex paleogeography of the east-central Gulf

  8. A possible cause of the Miocene uplift and volcanism in the central Anatolian plateau

    Microsoft Academic Search

    J. Bartol; R. M. Govers; M. J. Wortel

    2010-01-01

    During the middle and late Miocene (13-5Ma) several seemingly unrelated events occurred in central Anatolia, Turkey; (1) a new epoch of widespread volcanic activity with a mantle signature, (2) sudden uplift and disruption of a Oligocene-lower Miocene palaeo drainage system in the Western Taurus (southwest Turkey) and (3) a regional regression across southern Turkey (Antalya, Adana, Mut) coeval with volcanic

  9. 3D Paleotopographic and Paleobathymetric Reconstructions for the Early and Late Miocene

    NASA Astrophysics Data System (ADS)

    Scotese, C. R.

    2001-05-01

    During the Early Miocene, relatively warm Atlantic bottom water temperatures suggest that Antarctica was not yet covered by an extensive, permanent ice cap and that there was only seasonal ice cover in the northern hemisphere. By the middle late Miocene, however, global temperatures cooled dramatically as the Earth entered its current Ice House phase. A large circum-Antarctic ice sheet covered the south polar regions, and permanent ice began to accumulate in the northern hemisphere. Global cooling during the Miocene was caused, in part, by plate tectonic, paleogeographic and paleoceanographic events. During the Miocene, uplift of the Himalayas was accelerated, the circum-Antarctic current was strengthened, equatorial ocean currents were disrupted by the emerging Panama land-bridge and the collision of New Guinea with Southeast Asia. It was also during the Miocene that the Atlantic Ocean, Mediterranean Sea, and Indian Ocean became isolated as a result of the collision of Arabia with Iran and Turkey, and constriction across the Straits of Gibraltar. In order to better understand the plate tectonic, paleogeographic and paleoceanographic conditions that may have contributed to this time of global cooling, two, 3D paleogeographic models were built that illustrate the paleotopography of the continents and the paleobathymetry of the ocean basins during the early Miocene (Burdigalian, 20 Ma) and Late Miocene (Tortonian, 10 Ma). These 3D models were created by reconstructing present-day topography and bathymetry and removing features that were younger than Miocene in age. These 3D, digital paleogeographic models have a vertical resolution of 40 meters, and geographic resolution of approximately 10 km.

  10. Miocene basalts in northwestern Taiwan: Evidence for EM-type mantle sources in the continental lithosphere

    Microsoft Academic Search

    Sun-Lin Chung; Bor-Ming Jahn; Shu-Jen Chen; Typhoon Lee; Cheng-Hong Chen

    1995-01-01

    Cenozoic extension around the Taiwan Strait resulted in intraplate basalt volcanism in the Fujian-Taiwan region of the southeastern China continental margin. In northwestern Taiwan, the basalt volcanism took place in two distinct periods: the early Miocene (23–20 Ma), with the eruption of alkali basalt only, and the late Miocene (13–9 Ma), marked by the emplacement of various basalt types. The

  11. The Miocene Petroleum System of the Northern Apennines in the Central Po Plain (Italy)

    Microsoft Academic Search

    Vincenzo Picotti; Rossella Capozzi; Giuseppe Bertozzi; Fausto Mosca; Andrea Sitta; Maria Tornaghi

    We describe the Miocene petroleum system in the context of the geology of the Northern Apennines as a system fed by multiple\\u000a sources including some potential for deep oil accumulation. The presence of sources deeper than the Miocene reservoir is required\\u000a by the high thermal maturity of the oils, the thermogenic nature of methane and the high ion content, in

  12. Andean tectonics as a cause for changing drainage patterns in Miocene northern South America

    NASA Astrophysics Data System (ADS)

    Hoorn, Carina; Guerrero, Javier; Sarmiento, Gustavo A.; Lorente, Maria A.

    1995-03-01

    New data from Neogene strata in northern South America suggest that Miocene tectonism in the northeastern Andes was responsible for the genesis of the Amazon River and changes in the drainage patterns of other major rivers such as the Magdalena and the Orinoco. Here we present a new model for the paleogeographic evolution of northern South America during the Miocene. In the early Miocene, a large part of the drainage of northwest Amazonia was directed northward along the paleo Orinoco river system to a delta in Lake Maracaibo. Uplift of the Eastern Cordillera in the late middle Miocene caused the first development of the Amazon River; however, no connection with the Atlantic was established, and the Amazon fed the paleo Orinoco river system, which drained toward the Caribbean. Substantial Andean uplift in the late Miocene resulted in major changes in paleogeography: the Orinoco changed its course, the Amazon established a connection to the Atlantic, causing the drowning of carbonate platforms, and the Amazon Caribbean connection was closed. Thus the drainage and paleogeography of northern South America in the Miocene were strongly controlled by tectonic movements in the northeastern Andes.

  13. Paleoecology of middle and late Miocene Monterey Formation, Upper Newport Bay, Newport Beach, California

    SciTech Connect

    Carlos, A.P.; Douglas, R.G.

    1986-07-01

    The Miocene Monterey Formation exposed along the cliffs of Upper Newport Bay represents a lower calcareous facies dominated by foraminifera and coccoliths, indicating warm climate and low nutrient waters, and a siliceous facies consisting of diatomaceous rocks, which records high productivity as a result of climatic deterioration and intensified upwelling. Using the distribution and preservation of foraminifera in the California continental borderland basins as a modern analog, they interpret the effect of changing environmental (climatic and oceanographic) conditions during the middle and late Miocene on the distribution and preservation of foraminifera, calcareous nannofossils, radiolarians, diatoms, and sediments. Two stratigraphic sections were sampled: (1) middle Miocene (Luisian) section 1, and (2) late Miocene (upper Mohnian) section 2. Section 1 best correlates with the middle Miocene Sphenolithus heteromorphus nannofossil zone. Benthic foraminifera indicate deposition in upper bathyal to upper middle bathyal depths. Poor preservation of calcareous tests is generally associated with homogeneous sediments, whereas better preservation is correlated with indistinctly laminated rocks. Stratigraphic section 2, which accumulated in upper bathyal depths, covers parts of the early late Miocene (upper Mohnian) Denticulopsis hustedtii-D. lauta and D. hustedtii diatom zones. Foraminifera and nannofossils are generally more abundant and better preserved in well laminated sediments than in sediments with homogeneous to indistinct laminations. Benthic foraminifera favoring low oxygen conditions have low diversities in rocks with poorly preserved laminations, but have higher densities in well laminated intervals.

  14. Miocene karst drainage system: seismic stratigraphy of the continental shelf west of Florida

    SciTech Connect

    Herbert, J.A.

    1985-01-01

    High-resolution geophysical data recorded on the continental shelf west of Tampa Bay, Florida show three stratigraphic units: Holocene, Plio-Pleistocene, and Miocene. Within the Miocene unit is an expansive drainage system extending about 80 kilometers offshore. In most areas, a system such as this would typically be characterized as a paleo-fluvial system. Although this drainage system probably initiated fluvially, geophysical data showing much evidence of karstification suggest that this system probably formed on the inner shelf as a result of large scale dissolution and collapse of Miocene limestones during lowered sea-level. The overlying Plio-Pleistocene unit infills the Miocene drainage system, while exiguously covering Miocene rocks in areas where the system is absent. Deposition of this unit probably took place during high-stands of sea-level, followed by erosion and transport of sediment farther offshore, exposing Miocene rocks. The Holocene unit sporadically covers underlying units throughout the study area. Sediments making up this unit have been reworked into several bedform types probably resulting from various boundary layer flow events such as hurricanes, storms, currents and tides. This scenario is probably not unique to the continental shelf west of Tampa Bay, Florida, but may also characterize other karstic shelves where paleo-fluvial processes were previously thought to be the dominant mechanism forming paleo-coastal drainage systems.

  15. Simultaneous determination of vitexin-4?- O-glucoside and vitexin-2?- O-rhamnoside from hawthorn leaves flavonoids in rat plasma by HPLC method and its application to pharmacokinetic studies

    Microsoft Academic Search

    Guo Ma; Xue-Hua Jiang; Zhuo Chen; Jing Ren; Chen-Rui Li; Tai-Ming Liu

    2007-01-01

    The present study was to investigate the pharmacokinetics of the two similar flavonoid glycosides, vitexin-4?-O-glucoside (VGL) and vitexin-2?-O-rhamnoside (VRH) in rats after intravenous administration of hawthorn leaves flavonoids (HLF). Blood samples were collected via tail vein at time intervals after drug administration and the plasma concentrations of the studied ingredients were analyzed by HPLC after the plasma protein was precipitated

  16. Simultaneous determination of vitexin-4?-O-glucoside, vitexin-2?-O-rhamnoside, rutin and vitexin from hawthorn leaves flavonoids in rat plasma by UPLC–ESI-MS\\/MS

    Microsoft Academic Search

    Wenjun Zhang; Ming Xu; Chaoqun Yu; Guofeng Zhang; Xing Tang

    2010-01-01

    A sensitive and accurate ultra-performance liquid chromatography electrospray ionization tandem mass spectrometry (UPLC–ESI-MS\\/MS) method was developed and validated for the simultaneous determination of vitexin-4?-O-glucoside (VGL), vitexin-2?-O-rhamnoside (VRH), rutin (RUT) and vitexin (VIT) in rat plasma after intravenous administration of hawthorn leaves flavonoids (HLF). Following protein precipitation by methanol, the analytes were separated on an ACQUITY UPLC BEH C18 column packed

  17. Studies in Neotropical paleobotany. XIII. An Oligo-Miocene palynoflora from Simojovel (Chiapas, Mexico).

    PubMed

    Graham, A

    1999-01-01

    A plant microfossil assemblage of 24 identified and five unknown pollen and spore types is reported from the early Miocene La Quinta Formation near Simojovel, Chiapas, Mexico. The taxa group into seven paleocommunities representing versions of the modern mangroves (Pelliciera, Rhizophora), swamp and lowland riparian forest (Ceratopteris, Crudia, Pachira), tropical rain forest (Selaginella, cf. Antrophyum, Pteris, Sphaeropteris/Trichipteris, cf. Aguiaria, Crudia, Guarea, Pachira), lower montane rain forest (Alfaroa/Oreomunnea, possibly Eugenia), evergreen cloud forest [Picea, Pinus, Podocarpus, Ericaceae (possibly Cavendishia/Vaccinium)], evergreen seasonal forest (Hymenaea, Ilex, possibly Eugenia), and tropical deciduous forest (Cedrela). Elements of arid and high-elevation habitats were absent or few, and northern temperate elements (Picea, Pinus?) were few or rare. Paleoelevations are estimated at 1000-1200 m (present average 2000 m, maximum 3004 m), MAT (mean annual temperature) at least as warm as the present 24°C, and annual rainfall near the present ?2500 mm but more evenly distributed. The La Quinta (Simojovel) and other Tertiary floras from the region reflect a trend toward higher altitudes, more seasonal rainfall, cooling tempertures, increased introduction of cool-temperate elements from the north after ?15 Ma (million years), and increased introduction of tropical elements from the south after completion of the isthmian land bridge ?3.5 Ma ago. PMID:21680342

  18. Astrochronology of the Mediterranean Early and Middle Miocene

    NASA Astrophysics Data System (ADS)

    Hüsing, Silja Katherine; Hilgen, Frederik; Krijgsman, Wout; Turco, Elena

    2013-04-01

    An accurate high-resolution astronomical time scale is of crucial importance in Earth Sciences. It allows not only to reconstruct astronomical climate forcing but also to precisely date geological events, to determine rates of changes, and to discriminate between cause and effect related to fundamental processes controlling Earth's history. The accuracy, precision and resolution of the geological time scale for the Neogene have improved considerably over the last decades, thanks to the combination of an integrated stratigraphic approach and astronomical tuning, which resulted in the "Astronomically Tuned Neogene Time Scale" (ATNTS2004, ATNTS2012). The most recent ATNTS2012 (Gradstein et al. 2012) includes direct astronomical ages for chron boundaries back to ~15 Ma based on the tuning of marine successions from the Mediterranean. Reversal ages for the interval between 15 and 23 Ma were calculated from a seafloor-spreading-rate history model in combination with limited astronomical control. Completing the Neogene time scale should be exclusively based on deep marine sections. The most suitable section in the Mediterranean is the Monte dei Corvi-La Vedova-Spiaggia della Scalaccia composite section near Ancona in Italy as an integrated stratigraphy and astronomical tuning has been established for the Late to Middle Miocene interval (Hüsing et al. 2007, 2009, 2010, Mourik et al. 2010, Turco et al. 2011). The resultant astronomically tuned reversal ages have already been incorporated into the GTS (Gradstein et al. 2012). The section has now been further extended into the Early Miocene along the cliffs near Ancona (Spiaggia della Scalaccia composite section). We will present our high-resolution integrated stratigraphy including cyclostratigraphy, biostratigraphy, magnetostratigraphy, colour and elemental proxy records. The sedimentary cycle pattern is very complex in this interval, and we thus use the detailed colour and elemental proxy records to achieve a match with an astronomical target curve, which is different to the nominal astronomical solution. The astronomical tuning in turn provides accurate numerical ages for reversal boundaries, which, we suggest, should replace the existing ages in the ATNTS2012.

  19. Miocene squat lobsters (Decapoda, Anomura, Galatheoidea) of the Central Paratethys – a review, with description of a new species of Munidopsis

    PubMed Central

    Hyžný, M.; Gašpari?, R.; Robins, C.M.; Schlögl, J.

    2015-01-01

    All squat lobsters of the families Galatheidae, Munididae and Munidopsidae from the Miocene of the Central Paratethys are reviewed taxonomically. Based on additional observations emended diagnoses are provided for Agononida cerovensis and Galathea weinfurteri, from the Lower and Middle Miocene, respectively. Munidopsis is represented by two species in the study area; additional data for M. lieskovensis from the Lower Miocene of Slovakia are presented and a new species, M. palmuelleri, from the Middle Miocene of Slovenia is erected. Implications for palaeoenvironmental reconstructions are briefly discussed for each taxon. PMID:26005283

  20. Foraminiferal biostratigraphy and paleoenvironments of Eastover Formation (late Miocene), Virginia

    SciTech Connect

    Goshorn, J.H.

    1984-04-01

    Foraminifera from 50 samples taken from the Eastover Formation (Miocene) in Virginia are used in a study of biostratigraphy and paleoecology. The Eastover Formation contains two members: the lower Claremont Manor Member, a clayey, silty, poorly sorted, fine-grained sand which contains abundant foraminifera; and the upper Cobham Bay Member, a well-sorted, shelly, fine-grained sand that contains less abundant foraminifera. Planktonic species are used to establish a biochronology of the Eastover, while benthic species are used to interpret paleoecology, using the distribution of modern foraminifera as a basis. Evidence of changes in environments through time and varying sea margins is searched for by examination of samples taken from vertical sections and samples taken from different geographic locations within the study area. Additional evidence of paleoenvironments is gained by a grain size analysis of sediments from the formation. Synthesis of this information allows for reconstruction of the geologic history of the Eastover Formation in terms of environments changing through time and space. Cluster analysis and canonical variate analysis are used to clarify differences in foraminiferal content between and within the two members and to identify the taxa which cause such differences. Analysis of this type is helpful in revealing and foraminiferal assemblage zones present as well as quantifying data derived from the study.

  1. Late Miocene calcareous nannofossil genus Catinaster: taxonomy, evolution and magnetobiochronology

    USGS Publications Warehouse

    Peleo-Alampay, A.; Bukry, D.; Liu, L.; Young, J.R.

    1998-01-01

    A systematic study on the evolution and stratigraphic distribution of the species of Catinaster from several DSDP/ODP sites with magnetostratigraphic records is presented. The evolution of Catinaster from Discoaster is established by documentation of a transitional nannofossil species, Dicoaster transitus. Two new subspecies, Catinaster coalitus extensus and Catinaster calyculus rectus are defined which appear to be intermediates in the evolution of Catinaster coalitus coalitus to Catinaster calyculus calyculus. The first occurrence of C. coalitus is shown to be in the lower part of C5n.2n at 10.7-10.9 Ma in the low to mid-latitude Atlantic and Pacific oceans. The last occurrence of C. coalitus coalitus varies from the upper part of C5n.2n to the lower portion of C4A. Magnetobiostratigraphic evidence suggests that the FO of C. calyculus rectus is diachronous. Catinaster mexicanus occurs in the late Miocene and has been found only in the eastern equatorial Pacific, the Indian Ocean and the Gulf of Mexico.

  2. Late Oligocene-early Miocene birth of the Taklimakan Desert.

    PubMed

    Zheng, Hongbo; Wei, Xiaochun; Tada, Ryuji; Clift, Peter D; Wang, Bin; Jourdan, Fred; Wang, Ping; He, Mengying

    2015-06-23

    As the world's second largest sand sea and one of the most important dust sources to the global aerosol system, the formation of the Taklimakan Desert marks a major environmental event in central Asia during the Cenozoic. Determining when and how the desert formed holds the key to better understanding the tectonic-climatic linkage in this critical region. However, the age of the Taklimakan remains controversial, with the dominant view being from ?3.4 Ma to ?7 Ma based on magnetostratigraphy of sedimentary sequences within and along the margins of the desert. In this study, we applied radioisotopic methods to precisely date a volcanic tuff preserved in the stratigraphy. We constrained the initial desertification to be late Oligocene to early Miocene, between ?26.7 Ma and 22.6 Ma. We suggest that the Taklimakan Desert was formed as a response to a combination of widespread regional aridification and increased erosion in the surrounding mountain fronts, both of which are closely linked to the tectonic uplift of the Tibetan-Pamir Plateau and Tian Shan, which had reached a climatically sensitive threshold at this time. PMID:26056281

  3. Miocene fluvial-tidal sedimentation in a residual forearc basin of the Northeastern Pacific Rim: Cook Inlet, Alaska case study

    SciTech Connect

    Stricker, G.D.; Flores, R.M. [Geological Survey, Denver, CO (United States)

    1996-12-31

    Cook Inlet in southern Alaska represents a Cenozoic residual forearc basin in a convergent continental margin, where the Pacific Plate is being subducted beneath the North American Plate. This basin accumulated the >6,700-m-thick, mainly nonmarine, Eocene-Pliocene Kenai Group. These rocks contain biogenic coal-bed methane estimated to be as high as 245 TCF. Lignites to subbituminous coals with subsurface R{sub o} ranging from 0.38 to 0.73 percent and the stage of clay-mineral diagenesis and expandibility indicate a thermally {open_quotes}cool{close_quotes} basin. Miocene Tyonek and Beluga Formations compose 65 percent (>4,300 m thick) of the Kenai Group. The Tyonek includes conglomeratic sandstones, siltstones, mudstones, coals, and carbonaceous shales, interpreted as braided- stream deposits. These fluvial deposits are interbecided with burrowed, lenticular, and flaser-bedded sandstones, siltstones, and mudstones, interpreted as tidal deposits. Tyonek framework conglomerates formed in wet alluvial fans incised on paleovalleys of the Chugach terrane. Coal-forming mires are well developed on abandoned braided-stream deposits. Tyonek drainages formed in high-gradient alluvial plains inundated by tides similar to environments in the modern upper Cook Inlet. The upper Miocene Beluga consists of sandstones, siltstones, mudstones, carbonaceous shales, and coals deposited in meandering (low sinuosity) and anastomosed fluvial systems. These fluvial deposits alternated vertically with deposits of coal-forming mires. The Beluga drainages formed in low-gradient alluvial plains. The high-gradient Tyonek alluvial plain was probably controlled by provenance uplift and eustatic change, whereas the low-gradient Beluga alluvial plain was influenced by subdued provenance uplift and rapid basin subsidence. Rapid sedimentation on both these low- and high-gradient alluvial plains, which kept up with subsidence, produced a thermally {open_quotes}cool{close_quotes} basin.

  4. Regional biostratigraphy and paleoenvironmental history of Miocene of onshore and offshore Alabama

    SciTech Connect

    Smith, C.C. (Geological Survey of Alabama, Tuscaloosa (USA))

    1989-09-01

    Subsurface Miocene sediments of coastal Alabama and the adjoining state and federal waters consist of a clastic wedge varying in thickness from less than 1,000 ft in southern Alabama to a maximum of about 6,000 ft in the northeastern portion of the Main Pass area. Relatively deep-water and open-marine transgressive basal Miocene clays and shales unconformably overlie a gently southwestward-dipping late Oligocene-earliest Miocene carbonate platform. Middle and late Miocene sediments consist of a regressive offlapping sequence of sand and shale deposited in varying neritic paleoenvironments. Analysis of planktonic and benthonic foraminifera has resulted in a refined biostratigraphic zonation of these sediments, permitting the recognition of several regional time-equivalent datum levels, or biohorizons. These biohorizons are shown on a series of subsurface cross sections that show the dramatic southwestward thickening of middle and late Miocene sediments as well as illustrate the relationships of the producing intervals within the Cibicides carstensi and Discorbis 12 interval zones. The paleoenvironmental history of the Miocene has been reconstructed on a series of paleobathymetric maps drawn for selected regional biohorizons. Among other features, these maps have proven the existence and outlined the margins of previously unrecognized shallow-meritic deltaic sediments in southeastern Mobile County and in the Chandeleur and Viosca Knoll (north) areas. Analysis of sedimentation rates, which range from less than 25 to 1,370 ft/m.y., further aids in understanding the coastal shelf, deltaic, and open-marine depositional history of the Miocene of Alabama and the adjoining state and federal waters.

  5. Miocene ungulates and terrestrial primary productivity: Where have all the browsers gone?

    PubMed Central

    Janis, Christine M.; Damuth, John; Theodor, Jessica M.

    2000-01-01

    Progressive changes are observed in both the composition of mammal faunas and vegetation during the Miocene epoch [24–5 mega-annum (Ma)]. These changes are usually interpreted as a response to climatic changes. In the traditional view, forests or woodlands gradually gave way to more open habitats, with grazing (grass-eating) ungulate (hoofed) mammal species replacing the browsing (leafy-vegetation-eating) species as grasslands expanded. However, data from fossil assemblages in the Great Plains region of North America show that this faunal change was not a one-for-one replacement of browsers by grazers, as usually thought. Typical late early Miocene (17 Ma) fossil communities included extraordinarily high numbers of browsing ungulate species, comprising a fauna that cannot be directly analogized with any present-day community. Both maximum species richness of all ungulates and the proportion of browsers declined steadily in ungulate communities through the middle Miocene, to levels comparable to those of the present by the late Miocene. The resulting dramatic, cumulative loss of browsing species constitutes one of the strongest faunal signals of the late Tertiary (but was not a single “event”). We suggest that the early Miocene browser-rich communities may reflect higher levels of primary productivity in Miocene vegetation, compared with equivalent present-day vegetation types. The observed decline in species richness may represent a gradual decline in primary productivity, which would be consistent with one current hypothesis of a mid-Miocene decrease in atmospheric CO2 concentrations from higher mid-Cenozoic values. PMID:10884422

  6. Post-Miocene extension in Central Anatolia; It's linkage to Aegean extension

    NASA Astrophysics Data System (ADS)

    Rojay, Bora; Özsay?n, Erman

    2013-04-01

    Post-Miocene extension in Central Anatolia; It's linkage to Aegean extension Anatolian Plate, -where Central Anatolia situated on-, escapes westward onto African plate along Eastern Mediterranean-Cyprus subduction zone, sliding by North and East Anatolian faults. Central Anatolia is bounded by dextral North Anatolian Fault from north, Taurides from south and it is fragmented by strike slip faults evolving under N-S compression in east and by Aegean horst and grabens evolving under N-S extension in west. To be able to delineate and understand the deformational order in Central Anatolia and its linkage to Aegean region, various sectors with the Anatolia are chosen, namely, Ankara region (Beypazar? to Kazan Miocene basins), Eski?ehir region (Mihall?ç?k to ?nönü Miocene basins) in Central Anatolia, Gediz-Ala?ehir Graben and Efes areas in Western Anatolia are selected. To sum up, in a wide region from Central Anatolia to Western Anatolia, i. Unconformities btw uppermost Late Miocene and Plio-Quaternary, and btw Plio-Quaternary and Quaternary are clearly identified in both regions, ii) ENE-WSW to N-S compression (intense post-Late Miocene - pre-Pliocene folding) with almost E-W extension operates during post-Miocene (during Pliocene) is followed by a short lived strike slip deformation during Early Pliocene, and finally by NW-SE to WNW-ESE oriented multi directional extension during post-Plio-Quaternary. And in Gediz-Ala?ehir Graben and Efes (western Anatolia); a continuous NNE-SSW to NE-SW multi directed extension since post-Late Miocene following almost N-S compression (post-Early Miocene) operated. Dextral strike slip faulting with normal components and normal faulting with right lateral strike slip components are recorded on same fault planes, iii) Quaternary normal faulting post dates folding, reverse and strike slip faulting in both regions. However, right lateral strike slip faulting is recorded to the NW tip of the normal faults like Efes, Manisa and Eski?ehir faults, iv) under the new kinematic findings, the boundary conditions of neotectonic domains should have to be redefined in Anatolian plate, and v) during the escape of Anatolian plate towards east-southeast, based on the shift of principal stress directions counterclockwise block rotations can be operated along the "microplates" where northern blocks of the "microplates" are downthrown. Key words: normal faulting, extension, neotectonic domains, post-Miocene, central Anatolia.

  7. Early Miocene Antarctic glacial history: new insights from heavy mineral analysis from ANDRILL AND-2A drill core sediments

    NASA Astrophysics Data System (ADS)

    Iacoviello, Francesco; Giorgetti, Giovanna; Turbanti Memmi, Isabella; Passchier, Sandra

    2015-04-01

    The present study deals with heavy mineral analysis of late Early Miocene marine sediments recovered in the McMurdo Sound region (Ross Sea, Antarctica) during the ANDRILL—SMS Project in 2007. The main objective is to investigate how heavy mineral assemblages reflect different source rocks and hence different provenance areas. These data contribute to a better understanding of East Antarctica ice dynamics in the Ross Sea sector during the Early Miocene (17.6-20.2 Ma), a time of long-term global warming and sea level rise. The AND-2A drill core recovered several stratigraphic intervals that span from Early Miocene to Pleistocene and it collected a variety of terrigenous lithologies. The heavy mineral assemblages of the lower 650-m-thick sedimentary succession were analyzed through SEM observations and SEM-EDS microanalyses on heavy mineral grains. The heavy mineral analysis shows that the sediments are a mix of detritus dominated by McMurdo Volcanic Group sources most likely located in the present-day Mount Morning area (Proto-Mount Morning) with minor contribution from Transantarctic Mountains source rocks located west of the drill site. The heavy mineral assemblages in Interval 1 indicate that between 20.2 and 20.1 Ma, the grounding line of the ice sheet advanced to a position near the present-day Mount Morning volcanic center. During deposition of Interval 2 (20.1-19.3 Ma), the ice sheet most likely experienced a dynamic behavior with interval of ice advance alternating with periods of ice retreat, while Interval 3 (19.3-18.7 Ma) records further retreat to open water conditions. A dynamic behavior is noted in Interval 4 (18.7-17.6 Ma) with a decreasing contribution of materials derived from the basalts of the Mount Morning volcanic center located to the south of the drill site and a consequent increasing contribution of materials derived from the Transantarctic Mountains to the west of the drill site.

  8. Sequence stratigraphy, basin dynamics, and petroleum geology of the Miocene from eastern Tunisia

    SciTech Connect

    Bedir, M. [Campus Universitaire, Tunis (Tunisia)]|[Unite des Ressources Naturelles et Environnement, Hammam-Lif (Tunisia); Tlig, S. [Campus Universitaire, Tunis (Tunisia); Bobier, C. [Universite Bordeaux, Talence (France)] [and others

    1996-01-01

    On the eastern margin of Tunisia, Miocene limestones, marl, and siliciclastic deposits crop out poorly and are lacking in age-diagnostic faunal content. The biostratigraphic and lithostratigraphic subdivisions of these series are not clearly defined. A regional study of subsurface sequences of this margin (Cap Bon, Gulf of Hammamet, and Sahel) by means of sequence stratigraphy and subsurface structural analyses permits the identification of seven third-order sedimentary sequences of inferred Langhian to Messinian age, the boundaries of which are characterized by downlap and onlap/toplap relationships. These sequences include turbidites, sands, and sandstones deposited in connection with eustatic sea level changes and tectonic movements of east-west and south-north deep-seated faults due to the Alpine and Atlassic paroxysm. Stratal sequences are organized around Miocene syndepositional grabens, half-grabens, platforms, and folds occurring inside and outside of regional tectonic corridors. The geodynamic evolution of Miocene basins has led to the deposition of turbiditic black argillaceous source rocks, and sandstone and carbonate reservoirs that present new Miocene petroleum targets. The basin subsidence in response to the Alpine/Atlassic orogeny has permitted the maturation of Miocene source rocks, oil generation, and the formation of oil traps, stratigraphic pinch-outs, and structural enclosures on the flanks of folds and on the borders of grabens.

  9. Oligocene-Miocene Sr-isotope stratigraphy: Examples from eastern North America

    SciTech Connect

    Sugarman, P.J. (New Jersey Geological Survey, Trenton, NJ (United States)); Owens, J.P.; Gibson, T.G.; McCartan, L. (Geological Survey, Reston, VA (United States)); Feigenson, M.D. (Rutgers Univ., New Brunswick, NJ (United States))

    1994-03-01

    Sr-isotopic age estimates from the coastal plain in New Jersey, Maryland Virginia, and Florida have allowed correlation of upper Oligocene-Miocene stratigraphic sequences with an accuracy of [+-] 0.5--2.0 m.y. The upper Oligocene sequence mapped in New Jersey has an age range of 28.7--24.2 Ma, and is tentatively correlated with the Old Church Formation in Virginia. Sr-isotope age estimates of 28.6--25.3 in the lower part of the Arcadia Formation in Florida provide a chronostratigraphic correlation with the upper Oligocene, N.J. sequence. Miocene Sr-isotopic correlations are better constrained by improved age resolution of [+-]1 m.y. and less in the Miocene. The uppermost lower Miocene sequence in N.J. with Sr-isotopic age estimates of 17.4--15.5 Ma, can be correlated with the Calvert Formation in Maryland and the upper part of the Arcadia Formation in Florida based on Sr-isotopic correlations. The uppermost calcareous marine sequence in New Jersey is lower middle Miocene, with a Sr-isotopic age range of 13.6--12.2 Ma. This sequence is correlative with the Choptank Formation in Maryland. The St. Mary's Formation in Maryland has a Sr-isotopic age range of 10--9.6 Ma, and may be equivalent to the Cohansey Formation in New Jersey.

  10. Miocene-Pliocene transition in the southern Cyprus basins: The sedimentary expression of regional tectonic events

    SciTech Connect

    Orzag-Sperber, F.; Rouchy, J.M. (Universite Paris XI, Orsay (France))

    1988-08-01

    In the southern part of Cyprus, a Maastrichtian-Pleistocene sedimentary area fringes Troodos Mountain, a fragment of an ancient crust. During the Neogene, three basins formed in this area: Polemi, Pissouri, and Psematismenos. A deep marine condition has prevailed since the Maastrichtian. During the Paleocene and early Miocene, the sea gradually become shallower until the Messinian, where the most spectacular sedimentary event concerns the deposition of evaporites contemporaneous with other Mediterranean evaporites. Some sedimentary phenomena express the tectonic instability during the upper Miocene. A well-known tectonic event affecting the east Mediterranean region generally referred to as the Miocene-Pliocene phase occurs at the Miocene-Pliocene limit. Recent sedimentological studies indicate this event is in fact complex. The Tortonian-lower Pliocene period is marked by a constraint involving an N20 distension in the Polemi and Pissouri basins and an N100 distension in the Psematismenos basin. Sedimentologic studies have demonstrated three tectonic pulsations during the Messinian prior to the Pliocene transgression. These are expressed by two episodes of seismic brecciation and a paleoemersion indicated by paleosols and detrital discharges. These phenomena suggest brief tectonic instability during the Messinian. Microtectonic studies reveal that the main change in tectonic constraint does not coincide with the Miocene-Pliocene contact but occurs at the top of the lower Pliocene.

  11. Organic geochemical evaluations of bituminous rock and coals in Miocene Himmetoglu basin (Bolu, Turkey)

    SciTech Connect

    Sari, A.; Geze, Y. [Ankara University, Ankara (Turkey). Faculty of Engineering

    2008-07-01

    The studied area is a lake basin located in Bolu basin in Turkey. In the basin, from Upper Cretaceous to Upper Miocene 3,000-m thickness sediments were deposited. Upper Miocene Himmetoglu formation consisted of sandstone, claystone, and marl. To the middle level of the formation are located coal, bituminous limestone, and bituminous shales. In the basin, there are two coal beds whose thicknesses range from 1 to 13 m. The coals are easily breakable and black in color. In the coal beds exists some bituminous limestone and bituminous shales, and their thicknesses are between 5 and 45 cm. The amount of organic matter of the bituminous rocks from the Upper Miocene Himmetoglu formation are between 6.83 and 56.34 wt%, and the amount of organic matter of the bituminous limestone from the formation are between 13.58 and 57.16 wt%. These values indicate that these rocks have very good source potential. According to hydrogen index (HI), S2/S3, HI-T{sub max}, and HI-OI (oxygen index) parameters, kerogen types of the bituminous rocks and coals belonging to Upper Miocene Himmetoglu formation are Type I, Type II, and Type III. In accordance with HI, S2/S3, HI-T{sub max}, and HI-OI parameters, the bituminous rocks and coals from the Upper Miocene Himmetoglu formation are mostly immature.

  12. Mineralogy and diagenesis of miocene and pleistocene sediments, Northeastern Gulf of Mexico

    SciTech Connect

    Conner, S.P.; Denham, M.E.; Tieh, T.T.

    1988-01-01

    Cored Miocene and Pleistocene sediments from the northeastern Gulf of Mexico (ranging in depth from 1,400 to 2,000 m) consist of interbedded sands, silts, and muds with varying degrees of consolidation. Samples selected from these sediments were studied for their mineralogy and diagenesis. The Miocene sediments represent various subenvironments of the ancestral Mississippi River delta complex; Pleistocene sediments are marine shelf deposits. Sands from both Miocene and Pleistocene cores are fine to very fine-grained feldspathic litharenites with abundant (approx. = 25%) matrix fines and minor (<7%) carbonate clasts and shell fragments. Carbonate diagenesis is a continuing process in these sediments. Clayey sands contain disseminated siderite crystallites formed during organic matter fermentation. In clean sands, scattered thin (<15 cm) bands of poikilotopic carbonate-cemented sand are present in the middle of thicker unconsolidated intervals. Cemented bands are thicker in the Miocene section, having grown during burial through dissolution of shell fragments and reprecipitation at the margin of cemented zones. Diagenetic events evident in the Miocene core illustrate processes that could occur in the Pleistocene sediments with continued burial. These are: (1) dolomitization of some calcite cements, (2) precipitation of Fe-carbonate as crystallites, rims on dolomite cements, and overgrowths on siderite crystallites, and (3) zeolite formation on amorphous silica substrates. Amorphous silica is associated with limited dissolution of feldspars or lithic fragments.

  13. Miocene structure of Mustang Island, Mustang Island East Addition and part of Matagorda Island, Outer Continental Shelf areas, Gulf of Mexico

    E-print Network

    Kasande, Robert

    1995-01-01

    of about 1465 miles of multifold, migrated seismic reflection data, integrated with 35 well log data, served to detail the Miocene structure and its evolution. Early Miocene sedimentation resulted in differential loading of mobile substrates of shale...

  14. Computer modeling a Miocene carbonate platform, Mallorca, Spain

    SciTech Connect

    Bosence, D.W.J.; Waltham, D.A.; Lankester, T.H.G. (Royal Holloway Univ., London (United Kingdom)); Pomar, L. (Universitat de les Illes Balears (Spain))

    1994-02-01

    This paper describes a computer model based on algorithms that simulate processes of carbonate sediment production, deposition, erosion and redeposition, and sequence stratigraphy of carbonate platforms. We use the well-exposed cliff sections through the reef-rimmed Miocene carbonate platform of Mallorca, Spain, to test the ability of our program to simulate an outcropping stratigraphy. When an outcrop-derived sea level curve and the average Holocene rates of production and erosion are used in our model, we can precisely match the natural and the synthetic stratigraphies. In addition, we can reconstruct the nonoutcropping parts of the platform. This modeling indicates the ability of our program to simulate the sequence stratigraphy, stratal geometries, and facies of a real carbonate platform. This model also strongly suggests that the processes for which we have no field evidence and that we are not modeling, i.e., compaction, differential subsidence, and three-dimensional sedimentary processes, are unimportant factors in the development of the Llucmajor Platform of Mallorca. Modeling has contributed to three advances in carbonate platform analysis. First, this method is probably the best way to study the many effects that the different controlling parameters have on platform evolution. Secondly, if some parameters can be quantified from field analysis, then the other parameters can be bracketed from modeling. Thirdly, this method strongly suggests that the parameters we are not modeling have no important control on platform evolution. Accurate forward modeling of carbonate stratigraphies allows petroleum geologists to independently test sequence stratigraphic interpretations, reconstruct partially exposed or imaged carbonate stratigraphies, locate and quantify the cross sections of likely reservoir facies, illustrate the development and possible interconnections of reservoir facies, and predict stratigraphies around the basin rim. 41 refs., 9 figs., 1 tab.

  15. Emplacement of the Cabezo María lamproite volcano (Miocene, SE Spain)

    NASA Astrophysics Data System (ADS)

    Gernon, Thomas M.; Spence, Samuel; Trueman, Clive N.; Taylor, Rex N.; Rohling, Eelco; J. Hatter, Stuart; Harding, Ian C.

    2015-06-01

    Lamproite volcanoes are uncommon in the geological record but are exceptionally well preserved in the Betic Cordilleras of SE Spain, where they erupted during the Late Miocene (Tortonian to Messinian stages). The parent melts are thought to have been channelled through major lithospheric faults to erupt at or near the faulted margins of Neogene sedimentary basins. Lamproite magmas are thought to be relatively CO2-poor (<1 wt %) and are typically characterised by an effusive eruption style and the development of lava lakes and scoria cones. Cabezo María is a relatively small (˜550 m diameter) lamproite volcano that was emplaced within the shallow-water marine-influenced Vera Basin. The lamproites are compositionally similar to those of the Roman Province and generally less potassic (K2O<5 wt%) than other (ultra-) potassic rocks in SE Spain (e.g. Cancarix, Fortuna). The initial eruption stages were dominated by explosive magma-water interactions and the formation of peperites. These are characterised by angular fragments of glassy lamproite lavas (and isolated lobes) incorporated in sediments, locally showing the effects of thermal metamorphism. Further, elutriation pipes and `jigsaw-fit' textures are observed in the peperites. The lavas and peperites are overlain by outward-dipping well-stratified scoria deposits defining part of a cinder cone, which is inferred to have emerged above sea level. Steep internal contacts with inward-dipping, structureless breccias likely represent the inner wall deposits of a central conduit. The deposits are cross-cut by late-stage dykes, which supplied fissure eruptions of geochemically similar lavas capping the scoria cone. The transition from explosive to effusive behaviour may reflect the decreased availability of water, possibly due to downward migration of the feeder conduit below the level of water-saturated sediments.

  16. From transpression to transtension: Oligocene-Miocene structural evolution of the Vienna basin and the East Alpine-Western Carpathian junction

    Microsoft Academic Search

    L. Fodor

    1995-01-01

    Palaeostress analysis in the easternmost Alps and westernmost Carpathians revealed the existence of four different stress fields during Oligocene-Miocene times. The generalized Oligocene-late Middle Miocene maximal horizontal stress axis changes gradually from WNW-ESE to ENE-WSW and the Late Miocene axis trends to NNE-SSW. Except for the late Middle Miocene (late Sarmatian, 11 Ma) weak, transient stress field, the others reflect

  17. Characterizing the dispersal and distribution shapes of the geomagnetic field directions of the Late Miocene Columbia River Basalts

    NASA Astrophysics Data System (ADS)

    Dominguez, A. R.; Van Der Voo, R.

    2011-12-01

    This study comprises 118 discrete volcanic flows from the Late Miocene in the eastern Columbia River Basalt (CRB) Group with the aim of testing the distributions of the geomagnetic field directions, as predicted by various geomagnetic models. This is important because little is known empirically about the behavior of the geomagnetic field before the last 5 million years. The results of this study will allow us not only to extend the temporal coverage of geomagnetic field models, but also allow for potential improvements in these models. The rock magnetic analysis of the samples for this collection shows that the primary magnetic directions are uniformly carried by titanomagnetite throughout all the sites; some minor amounts of hematite are present, most likely formed during weathering. Thus, the magnetic behavior of the samples is caused by changes in the magnetic field and not due to changes in magnetic mineralogy. The paleomagnetic directions of the flows show southerly and up (N: 45, Dec: 180.1, Inc: -64.5, k: 25.7, alpha-95: 4.3) and northerly and down site means (N: 57, Dec: 6.3, Inc: 62, k: 29, alpha-95: 3.6). For reference, the local inclination of the geocentric co-axial dipole field is about 64 degrees. Furthermore, deviating directions are also present, possibly due to excursions as part of secular variation, or as intermediate transitions between reversed and normal polarity intervals. No new rock ages were necessary for this study since the CRB has undergone extensive geochronological study with high-quality, reproducible results. Additionally, integrating the ages of the flows and their corresponding paleomagnetic directions will allow us to observe the evolution of the paleosecular variation (PSV) for the Late Miocene, which can be compared with the published characteristics of the geomagnetic field in the last 5 million years.

  18. Partial record of a Miocene geomagnetic field excursion: Paleomagnetic data from the Paiute Ridge volcanic center, southern Nevada

    SciTech Connect

    Ratcliff, C.D.; Geissman, J.W.; Perry, F.V. (Univ. of New Mexico, Albuquerque, NM (United States)); Crowe, B.M. (Los Alamos National Lab., Las Vegas, NV (United States))

    1993-04-01

    In the Palute Ridge area, northern Halfpint Range, a complex system of late Miocene (about 8.5 Ma) intrusive and extrusive alkaline mafic rocks crops out over an area of about 25km[sup 2]. Post-magmatic faulting and erosion have resulted in excellent exposure of this sub-volcanic center, allowing for a detailed study of mechanisms and timing of magma emplacement. Paleomagnetic data have been obtained from over 50 sites in mafic rocks, and host ash-flow tuffs and carbonate strata, to better understand the duration of magmatic activity. Magnetizations, isolated in progressive alternating field and thermal demagnetization, for most of the sites at Palute Ridge deviate significantly from expected directions for a time-averaged late Miocene field. Demagnetization data show that there are two types of sample behavior. First, samples with close to expected reverse polarity directions (e.g., the chilled margin of a sill, D=209.2, l=[minus]36.4, [alpha]95=13.2, N=5, k=34.8). Second, and far more common, are samples giving magnetizations of southwest to northwest declination, with both shallow to moderate positive and negative inclination. Within this second grouping are several sites, including syenite pods which differentiated in situ from a large lopolith, having mean declinations that are due west and of shallow inclination. Contact tests performed at several sites are positive and show a clear correlation between sample position and isolated remanence direction. The authors preferred interpretation of the anomalously directed magnetization is that these rocks acquired a TRM during either a high amplitude excursion, or the transitional portion of a field reversal. Thermal models based on larger intrusions [+-] 10m thick at Paiute Ridge indicate that the magmas could cool through estimated magnetization blocking temperatures within weeks or months of emplacement.

  19. Miocene to recent ice elevation variations from the interior of the West Antarctic Ice sheet: Constraints from geologic observations, cosmogenic

    E-print Network

    Mukhopadhyay, Sujoy

    1 Miocene to recent ice elevation variations from the interior of the West Antarctic Ice sheet-term (Miocene-Holocene) WAIS elevation from the interior of the ice sheet near the WAIS divide. We use geologic observations and measurements of cosmogenic 21 Ne and 10 Be in bedrock surfaces to constrain WAIS elevation

  20. Four new species of benthonic foraminifera from the Miocene of Trinidad, West Indies, and their palaeobiogeographic importance

    Microsoft Academic Search

    Brent WILSON

    Four new species of benthonic foraminifera (Textularia carrbrowni, T. framptoni, T. sawhi and Bolivina jiattongi) are described from the middle and upper Miocene of Trinidad, West Indies. Textularia carrbrowni n. sp. has previously been illustrated from the Miocene of Puerto Rico as T. articulata D?ORBIGNY, in turn originally described from the Vienna Basin, Austria. The recognition of T. carrbrowni as

  1. OligoceneMiocene basin evolution in SE Anatolia, Turkey: constraints on the closure of the eastern Tethys gateway

    E-print Network

    Utrecht, Universiteit

    Oligocene­Miocene basin evolution in SE Anatolia, Turkey: constraints on the closure of the eastern, The Netherlands 3 Department of Geology, Firat University, Elazig, Turkey 4 Natural History Museum Vienna, Austria, we focus on the evolution of Oligocene and Miocene foreland basins in the southernmost part of Turkey

  2. A SKULL OF ANCYLOTHERIUM (CHALICOTHERIIDAE, MAMMALIA) FROM THE LATE MIOCENE OF THERMOPIGI (SERRES, N.GREECE), AND THE RELATIONSHIPS

    E-print Network

    Paris-Sud XI, Université de

    1 A SKULL OF ANCYLOTHERIUM (CHALICOTHERIIDAE, MAMMALIA) FROM THE LATE MIOCENE OF THERMOPIGI (SERRES has yielded a well- preserved skull of Ancylotherium pentelicum, among a rich collection of late Miocene mammals. It is the most complete Ancylotherium skull ever reported, and lack of crushing makes

  3. Ramu basin, Papua New Guinea: A record of late Miocene terrane collision

    SciTech Connect

    Cullen, A.B. [Univ. of Oklahoma, Norman, OK (United States)

    1996-05-01

    The Ramu basin lies along a plate boundary where the Finisterre terrane is colliding with the Indo-Australian plate. Estimates for the age of initial collision range from early Miocene to middle Pliocene. Two unsuccessful wells (Keram 1 and Tsumba 1) drilled to basement and two-dimensional seismic data show that folded and faulted early to middle Miocene carbonates and clastics (the Wogamush sequence) are overlain by relatively undeformed Pliocene marine clastics (the Wewak sequence) along a regional unconformity. The pre-Pliocene section, which is at the crux of resolving the age of initial collision, has been correlated previously to the Finisterre terrane. Clastics within that section, derived from older terranes south of the basin, imply an early Miocene age for collision. I propose that Miocene sedimentary and volcanic rocks in the two wells are correlative with the Wogamush beds of the Maramuni arc. The Ramu basin can then be viewed as having a two-stage evolution. During the Miocene, the basin was part of the Maramuni arc, the polarity of which is unresolved. A collisional successor basin developed in the late Miocene as the Finisterre terrane (Adelbert block) collided with the arc. Thrust faults on the northeastern side of the basin, truncated by a regional unconformity, are interpreted to mark the suture of the Adelbert block. A northern earliest Pliocene sediment source for the basal Wewak sequence was probably the Finisterre terrane, but multiple source areas are inferred for the rest of that sequence. Middle Pliocene inversion of the basin`s northeastern flank, characterized by reverse faulting and forced folding, is attributed to plate boundary reorganization caused by rifting in the Bismarck Sea. The Ramu basin has numerous untested structures related to both collision and basin inversion. Gas-prone source rocks are present, but are largely immature. Reservoir and charge considerations place the Ramu basin in the very high risk sector for exploration.

  4. Unusual Braarudosphaera bigelowii and Micrantholithus vesper enrichment in the Early Miocene sediments from the Slovenian Corridor, a seaway linking the Central

    E-print Network

    Gilli, Adrian

    Unusual Braarudosphaera bigelowii and Micrantholithus vesper enrichment in the Early Miocene During a stratigraphic survey of an Early Miocene sedimentary sequence outcropping in SE Slovenia in the lower Early Miocene, corresponding to the Egerian stage of the Central Paratethys and the Aquitanian

  5. Constraints on Miocene oceanography and climate in the Western and Central Paratethys: O-, Sr-, and Nd-isotope compositions of marine fish and

    E-print Network

    Schöne, Bernd R.

    Constraints on Miocene oceanography and climate in the Western and Central Paratethys: O-, Sr Accepted 8 October 2008 Keywords: Oxygen Strontium Neodymium Isotopes Shark teeth Mammal remains Miocene­Himalayan orogeny in the Oligo-Miocene. Sediments from the northern Alpine Molasse Basin, the Vienna

  6. Use of 3-Dimensional Dynamic Modeling of CO2 Injection for Comparison to Regional Static Capacity Assessments of Miocene Sandstone Reservoirs in the

    E-print Network

    Texas at Austin, University of

    Capacity Assessments of Miocene Sandstone Reservoirs in the Texas State Waters, Gulf of Mexico Wallace, K.1, Bureau of Economic Geology, Austin, TX A 14,467 sq. mi area of the coastal and offshore Texas Miocene. Capacity was calculated for the entire Miocene interval above overpressure and below non-supercritical CO2

  7. Giant taro and its relatives: A phylogeny of the large genus Alocasia (Araceae) sheds light on Miocene floristic exchange in the Malesian region

    E-print Network

    Renner, Susanne

    on Miocene floristic exchange in the Malesian region Lars Nauheimer a, , Peter C. Boyce b , Susanne S. Renner 2011 Available online 22 December 2011 Keywords: Ancestral area reconstruction Colocasia Miocene reached from Borneo 4­5 times in the Late Miocene and Early Pliocene, and the Asian mainland 6­7 times

  8. BIOSTRATIGRAPHY AND MAGNETOSTRATIGRAPHY OF THE MID-MIOCENE RAILROAD CANYON SEQUENCE, MONTANA AND IDAHO, AND AGE OF THE MID-TERTIARY

    E-print Network

    California at Berkeley, University of

    ARTICLE BIOSTRATIGRAPHY AND MAGNETOSTRATIGRAPHY OF THE MID-MIOCENE RAILROAD CANYON SEQUENCE regional uplift between ca. 16.8 and 17.5 Ma. INTRODUCTION Chronologic control on middle Miocene mammal et al., 2004); and (4) a clear understanding of Miocene geological history in the region. The primary

  9. Carnets de Gologie / Notebooks on Geology -Memoir 2005/01 (CG2005_M01) Discoaster zonation of the Miocene of the Kutei Basin, East Kalimantan,

    E-print Network

    Boyer, Edmond

    of the Miocene of the Kutei Basin, East Kalimantan, Indonesia (Mahakam Delta Offshore). Bernard LAMBERT 1 Cécile defined and used in the Miocene Kutei Basin of eastern Borneo to establish a regional stratigraphic; delta; Discoaster; Kutei; Mahakam; Miocene; nannoflora; nannofossil; Neogene; stratigraphy; zonation

  10. First joint record of Mesopithecus and cf. Macaca in the Miocene David M. Alba a,b,*, Eric Delson c,d

    E-print Network

    Delson, Eric

    First joint record of Mesopithecus and cf. Macaca in the Miocene of Europe David M. Alba a Available online 15 December 2013 Keywords: Colobinae Cercopithecinae Fossil monkeys Miocene Moncucco-evaporitic Messinian (5.40e5.33 Ma, MN13, latest Turolian, latest Miocene) locality of Moncucco Torinese (Tertiary

  11. Scripta Fac. Sci. Nat. Univ. Masaryk. Brun., Volume 36, Geology. Brno, 2007. 57 The Early Miocene micromammalian assemblage from Mokr 1/2001 Turtle

    E-print Network

    Horacek, Ivan

    Scripta Fac. Sci. Nat. Univ. Masaryk. Brun., Volume 36, Geology. Brno, 2007. 57 The Early Miocene-mail: horacek@natur.cuni.cz Key words: Lagomorphs, Rodents, Insectivores, Bats, Early Miocene (MN 4), Mokrá ­ 1/2001 Turtle Joint, Moravia Abstract The age of micromammalian assemblage from new Early Miocene site of Mokrá

  12. Red Sea oil shows attract attention to Miocene salt, post-salt sequence

    SciTech Connect

    Nagati, M. (International Petroleum Corp. (United States))

    1992-12-07

    This paper reports that for several decades oil companies have failed to mimic the traditional play concept of the Gulf of Suez by targeting potential oil reservoirs below the Upper/Middle Miocene salt in the Red Sea. The absence of a Pre-Miocene sequence in the majority of outcrops on both sides of the rift and its assumed absence in the subsurface, together with the perception of the Red Sea being geothermally hot and only gas-prone, have led to an exploration lull in this 280,000 sq mile intracratonic rift basin.

  13. Eocene and miocene rocks off the northeastern coast of the United States

    USGS Publications Warehouse

    Gibson, T.G.

    1965-01-01

    A grab sample from a depth of 1675 m at a point south of Cape Cod contains early Eocene planktonic Foraminifera and is correlated with the Globorotalia rex zone of Trinidad. The assemblage indicates a depth comparable to that existing today. Regional relations suggest that the Cretaceous and Eocene deposits deepen to the west toward New Jersey. Two mollusk-bearing blocks dredged from the northern side of Georges Bank are correlative with the Miocene Yorktown Formation. Rocks from two other stations are probably Miocene. Benthonic Foraminifera in one sample indicate deposition in cool temperate waters of less than 60 m depth. ?? 1965.

  14. Amber from western Amazonia reveals Neotropical diversity during the middle Miocene

    PubMed Central

    Antoine, Pierre-Olivier; De Franceschi, Dario; Flynn, John J.; Nel, André; Baby, Patrice; Benammi, Mouloud; Calderón, Ysabel; Espurt, Nicolas; Goswami, Anjali; Salas-Gismondi, Rodolfo

    2006-01-01

    Tertiary insects and arachnids have been virtually unknown from the vast western Amazonian basin. We report here the discovery of amber from this region containing a diverse fossil arthropod fauna (13 hexapod families and 3 arachnid species) and abundant microfossil inclusions (pollen, spores, algae, and cyanophyceae). This unique fossil assemblage, recovered from middle Miocene deposits of northeastern Peru, greatly increases the known diversity of Cenozoic tropical–equatorial arthropods and microorganisms and provides insights into the biogeography and evolutionary history of modern Neotropical biota. It also strengthens evidence for the presence of more modern, high-diversity tropical rainforest ecosystems during the middle Miocene in western Amazonia. PMID:16950875

  15. Provenance Analysis of Lower Miocene Sediments in the Lower Austrian Molasse Basin

    NASA Astrophysics Data System (ADS)

    Knierzinger, Wolfgang; Palzer, Markus; Wagreich, Michael

    2015-04-01

    In the Early Miocene (Late Ottnangian) a global drop of the sea level and the continuous rise of the Alps caused a regression of the Paratethys. During this time interval the Traisen Formation (formerly Oncophora beds) was deposited in the Lower Austrian Molasse Basin. These yellowish-brownish to greyish mica-rich and carbonate-free sands and silts with clayish interlayers were originally named after a brackish water bivalve ("Oncophora"- now Rzehakia). The southeastern part of the TF partly interfingers with finer sands of the Dietersdorf Formation (DF). The Pixendorf Group combines the TF and the DF [coarse sands, conglomerates, blocks] of the Upper Ottnangian lithostratigraphic units in Lower Austria. West to the Waschberg Zone a deeper-water environment (so called Oncophora beds in former literature, herein [informally] renamed to Wildendürnbach Member) with sediment gravity flows (turbidites, muddy/sandy slumps) is inferred from OMV well data. Examinations of these fine sandstones, silts and laminated pelites have been carried out on the basis of the Wildendürnbach-4 OMV drilling core. Analyses of the TF revealed rather homogenous heavy mineral assemblages, dominated by high amounts of garnet (~65%) and relatively high amounts of epidote/zoisite (~10%) and amphiboles (~10%). Conducted surveys point towards a primary influence of metamorphic (metapelitic) source rocks of Austroalpine Crystalline Complexes of the rising Eastern Alps. Heavy mineral analysis of the WDK-4 drilling core showed even higher amounts of garnet (~80%) combined with minor amounts of rutile, staurolite, apatite, epidote/zoisite, tourmalines, zircon and amphiboles. Consistent heavy mineral assemblages and chemical data (EMPA) suggest a stratigraphical correlation with the K?epice Formation and the Ždánice-Hustope?e Formation in the Czech Republic and sedimentary influence from the Western Carpathian Flysch Belt.

  16. The Miocene Sommières basin, SE France: Bioclastic carbonates in a tide-dominated depositional system

    NASA Astrophysics Data System (ADS)

    Reynaud, Jean-Yves; James, Noël P.

    2012-12-01

    The Miocene Sommières Basin in SE France is a semi-enclosed depression that was connected to the Mediterranean Sea by a flooded paleo-incised valley and then filled by a suite of sediments comprising carbonate grains coming from temperate factories that were largely deposited in tidal-dominated paleoenvironments. The strata are partitioned into two sequences that reflect repeated flooding of the incised valley system, one of several similar situations in this region of France. The carbonate grains are mostly bioclasts, namely from barnacles, bryozoans, coralline algae (encrusting, branching, and rhodoliths), echinoids, and benthic foraminifers (large and small) with ostracods, sponge spicules and planktic foraminifers prominent in muddy facies. Particles were produced by shallow water carbonate factories on hard substrates (valley walls in particular), associated with subaqueous dunes, and in deeper water basinal settings. Each depositional sequence is underlain by an eroded and bored hard surface that is progressively overlain by TST subaqueous tidal dunes or storm deposits that grade up, in one case, into HST marls (the HST of the upper sequence has been removed by erosion). The lower sequence is ebb tide dominated whereas the upper sequence is flood tide dominated. The succession is interpreted to represent a TST whose tidal currents were focused by the narrow valley and a HST that reflected flooding of the overbanks. This stratigraphic and depositional motif is comparable to that in other spatially separated Neogene paleovalleys that are filled with tide-dominated clastic carbonates in the region. Together with other recently documented similar systems, these limestones constitute an important new group of carbonate sand bodies in the carbonate depositional realm.

  17. Carbonate platform growth and demise offshore Central Vietnam: Effects of Early Miocene transgression and subsequent onshore uplift

    NASA Astrophysics Data System (ADS)

    Fyhn, Michael B. W.; Boldreel, Lars O.; Nielsen, Lars H.; Giang, Tran C.; Nga, Le H.; Hong, Nguyen T. M.; Nguyen, Nguyen D.; Abatzis, Ioannis

    2013-10-01

    Miocene carbonate platforms cover a large part of the Central Vietnamese South China Sea margin. Early carbonate deposition took place on two regional platforms separated by a narrow depression developed along the trace of the East Vietnam Boundary Fault Zone. West of the East Vietnam Boundary Fault Zone, the Tuy Hoa Carbonate Platform fringes the continental margin between Da Nang and Nha Trang. Here, platform growth initiated during the Early Miocene and continued until Middle Miocene time when regional uplift led to subaerial exposure, termination of platform growth and karstification. East of the fault zone, the Triton Carbonate Platform was also initiated during the Early Miocene. Carbonate growth thrived during Early and part of Middle Miocene time and a thick, clean Lower and Middle Miocene carbonate succession cover the Triton Horst and the Qui Nhon Ridge. During the Middle Miocene, partial drowning resulted in the split-up of the Triton Carbonate Platform. Repeated partial drowning events throughout the Middle and Late Miocene resulted in westwards retreat of platform growth and eventual platform drowning and termination of carbonate deposition. Modern carbonate growth continues on isolated platforms hosting the Paracel Islands farther seawards. The onset of widespread carbonate deposition largely reflects the Early Miocene transgression of the area linked with early post-rift subsidence and the opening of the South China Sea. The mid-Neogene shift in carbonate deposition is interpreted as a consequence of regional uplift and denudation of central and south Indochina starting during Middle Miocene time when the Tuy Hoa Carbonate Platform became subaerially exposed. Stressed carbonate growth conditions on the Triton Carbonate Platform probably resulted from increased inorganic nutrient input derived from the uplifted mainland, possibly enhanced by deteriorated climatic conditions and rapid sea-level fluctuations promoting platform drowning.

  18. Spirochete and protist symbionts of a termite (Mastotermes electrodominicus) in Miocene amber

    Microsoft Academic Search

    Andrew Wier; Michael Dolan; David Grimaldi; Ricardo Guerrero; Jorge Wagensberg; Lynn Margulis

    2002-01-01

    Extraordinary preservation in amber of the Miocene termite Mastotermes electrodominicus has led to the discovery of fossil symbiotic microbes. Spirochete bacteria and wood-digesting protists were identified in the intestinal tissue of the insect. Fossil wood (xylem: developing vessel-element cells, fibers, pit connections), protists (most likely xylophagic amitochondriates), an endospore (probably of the filamentous intestinal bacterium Arthromitus = Bacillus), and large

  19. Geochemical constraints on the Palaeocene^ Miocene evolution of eastern Azerbaijan, with

    E-print Network

    Johnson, Cari

    Geochemical constraints on the Palaeocene^ Miocene evolution of eastern AzerbaijanEarth and Environmental Sciences, University of Texas at Arlington, Arlington,TX, USA zAzerbaijan NationalAcademy of Sciences Geology Institute ^ 29 A. H. Javid Pr., Baku, Azerbaijan ABSTRACT Fine-grained Palaeogene

  20. Sequence stratigraphy, basin dynamics, and petroleum geology of the Miocene from eastern Tunisia

    Microsoft Academic Search

    M. Bedir; S. Tlig; C. Bobier

    1996-01-01

    On the eastern margin of Tunisia, Miocene limestones, marl, and siliciclastic deposits crop out poorly and are lacking in age-diagnostic faunal content. The biostratigraphic and lithostratigraphic subdivisions of these series are not clearly defined. A regional study of subsurface sequences of this margin (Cap Bon, Gulf of Hammamet, and Sahel) by means of sequence stratigraphy and subsurface structural analyses permits

  1. Lithofacies, diagenetic spectra and sedimentary cycles of messinian (Late Miocene) evaporites in SE Spain

    Microsoft Academic Search

    Dieter Michalzik

    1996-01-01

    Messinian evaporites have been deposited within a number of connected basins that formed the so-called ‘Betic Strait’ in SE Spain during the Late Miocene. Pre-, syn- and postevaporitic sedimentary successions may well be compared with other strata of the same age surrounding the Mediterranean Sea. There is no evidence for a cataract-like connection of these basins with a strong unidirectional

  2. The coast redwoods ( Sequoia, Taxodiaceae) from the Eocene of Heilongjiang and the Miocene of Yunnan, China

    Microsoft Academic Search

    Qing-Wen Ma; Feng-Lan Li; Cheng-Sen Li

    2005-01-01

    Foliated shoots of Sequoia are reported from the Eocene of Yilan, Heilongjiang Province, NE China and from the Miocene of Lühe, Yunnan Province, South China. The leaves from both Yilan and Lühe are linear in shape, coriaceous in texture and the leaf base is decurrent and attached obliquely to the axis of shoots. The walls of the epidermal cells are

  3. Plant macrofossils from the Foulden Hills Diatomite (Miocene), Central Otago, New Zealand

    Microsoft Academic Search

    Mike Pole

    1996-01-01

    Twenty eight taxa of angiosperm fossils are described from the Early Miocene (c. 20 Ma) Foulden Hills Diatomite, not far from Dunedin, New Zealand. Some leaves include cuticle, and this has sometimes facilitated identification. Families confidently identified include Euphorbiaceae, Lauraceae, Myrsinaceae, Myrtaceae, Sapindaceae, and Smilacaceae, and, less confidently, Cunoniaceae and\\/or Elaeocarpaceae, Hernandiaceae, Leguminosae, Meliaceae or Rutaceae, Sterculiaceae, Tiliaceae, and Winteraceae.

  4. A remarkable new pygmy grasshopper (Orthoptera, Tetrigidae) in Miocene amber from the Dominican Republic

    PubMed Central

    Heads, Sam W.; Thomas, M. Jared; Wang, Yinan

    2014-01-01

    Abstract A new genus and species of pygmy grasshopper (Orthoptera: Tetrigidae) is described from Early Miocene (Burdigalian) Dominican amber. Electrotettix attenboroughi Heads & Thomas, gen. et sp. n. is assigned to the subfamily Cladonotinae based on the deeply forked frontal costa, but is remarkable for the presence of tegmina and hind wings, hitherto unknown in this subfamily. PMID:25147472

  5. Pliocene and latest Miocene anisotropy of magnetic susceptibility (AMS) from the Wilkes Land margin (Invited)

    NASA Astrophysics Data System (ADS)

    Sugisaki, S.; Tauxe, L.; Iwai, M.; van de Flierdt, T.; Cook, C.; Jimenez, F. J.; Khim, B.; Patterson, M. 0; Mckay, R. M.; Passchier, S.; Roehl, U.; González, J. J.; Escutia, C.

    2013-12-01

    During IODP Expedition 318, Sites U1359 and U1361 were drilled on the continental rise offshore the Wilkes Subglacial Basin to reconstruct the stability of the East Antarctic Ice Sheet (EAIS) during Neogene warm periods, such as the late Miocene and the early Pliocene. As the drilled core contains a complex history of compaction, erosion (thus hiatuses), and likely artificial disturbances, identifying these is important for reconstructing paleoenvironments. Anisotropy of magnetic susceptibility (AMS) is sensitive to lithological changes and differential compaction. At both sites, highly anisotropic layers correspond with turbidite units, lithologic boundaries and hiatuses. In places, it appears that low anisotropy is controlled by the bioturbated units and high productivity layers. Here we present a detailed study of the relationships between sediment compaction, based on AMS fabric variations in sedimentary records, and magnetic mineralogy. A clear correlation can be found between the degree of anisotropy and moisture content and diatom abundance during the Pliocene, but this pattern breaks down in the late Miocene. There are also strong rock magnetic indications for changes in the sources of the magnetic minerals throughout the Miocene to Pliocene. Furthermore, a significant difference exists between magnetic minerals at Sites U1359 and U1361. We will use our AMS and rock magnetic study to 1) characterize sediment compaction with biological productivity, and 2) detect the source of magnetic mineralogy throughout the late Miocene to Pliocene at both sites.

  6. Late Miocene paleoenvironments and tectonic setting of the southern margin of Cyprus and the Eratosthenes Seamount 

    E-print Network

    Robertson, Alastair H F

    1998-01-01

    During drilling of Leg 160 in the Eastern Mediterranean (April-May, 1995), Messinian (i.e., uppermost Miocene) facies were identified at a site at the base of the Cyprus slope (Site 968) and at two sites on the Eratosthenes ...

  7. A Late Miocene-Pliocene origin for the Central Himalayan inverted metamorphism

    Microsoft Academic Search

    T. Mark Harrison; F. J. Ryerson; P. Le Fort; An Yin; Oscar M. Lovera; E. J. Catlos

    1997-01-01

    Perhaps the best known occurrence of an inverted metamorphic sequence is that found immediately beneath the Himalayan Main Central Thrust (MCT), generally thought to have been active during the Early Miocene. However, in situ 208Pb\\/232Th dating of monazite inclusions in garnet indicates that peak metamorphic recrystallization of the MCT footwall occurred in this portion of the central Himalaya at only

  8. Upper Miocene to Recent Magnetic Stratigraphy in Deep-Sea Sediments

    Microsoft Academic Search

    John H. Foster; Neil D. Opdyke

    1970-01-01

    Two of the longest piston cores of deep-sea sediment ever recovered were taken in the equatorial Pacific on the twelfth cruise of the research vessel Robert D. Conrad. The two cores, 26 and 28 meters in length, penetrate calcareous and siliceous ooze to sediments of Miocene age. Paleomagnetic measurements were made on samples partially demagnetized in a 60-Hz alternating field

  9. Carbonate depositional environments and reservoir properties of the Miocene rocks, east Gulf of Suez, Egypt

    SciTech Connect

    Bakarat, M.A.K.; Kholief, M.M.

    1988-08-01

    Miocene carbonate rocks in six surface sections on the eastern side of the Gulf of Suez were carefully studied in the field, petrographically examined, and mineralogically analyzed using SEM and x-ray microanalysis for all elements. In general, reservoir quality of the Miocene carbonates was poor because of original composition and texture. Three different types of porosity were distinguished in the studied Miocene carbonates: primary (intergranular and moldic), secondary (leached), and fracture. Much of the porosity in the Miocene reservoirs is secondary; however, sometimes this secondary porosity may be reduced by compaction and/or precipitation of evaporites in fractures and pores. The authors conclude that the primary porosity of the carbonate rocks in the reef complex was eliminated by lithification and cementation; only secondary porosity remained. This secondary porosity developed in all environments (supratidal, intertidal, and subtidal), but the best porosity developed in the subtidal facies. This high porosity occurs because the dolomites in the subtidal facies are coarser and free from anhydrite cement, whereas in supratidal and intertidal facies the dolomites are finer and their porosity is plugged by secondary anhydrite cement.

  10. Paleogeographic evolution of the Late Miocene Lake Pannon in Central Europe

    Microsoft Academic Search

    Imre Magyar; Dana H Geary; Pál Müller

    1999-01-01

    The paleogeographic evolution of Lake Pannon within the Pannonian basin is reconstructed with eight maps, ranging from the Middle Miocene to the Early Pliocene. The maps are based on the distribution of selected biozones and specific fossils, and on complementary sedimentological and seismic information. Our reconstruction shows that the history of Lake Pannon can be divided into three distinct intervals:

  11. Circum-Mediterranean Oligo–Miocene biogeographic evolution – the gastropods’ point of view

    Microsoft Academic Search

    Mathias Harzhauser; Werner E. Piller; Fritz F. Steininger

    2002-01-01

    Based on studies in Iran (Qom Basin, Esfahan–Sirjan Basin, Zagros Mountains), in Turkey (Mut and Sivas basins), in the Mesohellenic Basin, and in northeastern Egypt, a new palaeobiogeographic concept for the Oligocene and Miocene in the circum-Mediterranean area with special emphasis on the distribution patterns of gastropod faunas is presented. A very strict biogeographic terminology is proposed to avoid the

  12. Miocene stable isotope record: a detailed deep Pacific Ocean study and its paleoclimatic implications

    Microsoft Academic Search

    F. Woodruff; S. M. Savin; R. G. Douglas

    1981-01-01

    Deep Sea Drilling Project site 289 in the western equatorial Pacific has yielded an extremely detailed record of the carbon and oxygen isotopic changes in the Miocene deep ocean. The isotopic record reflects major changes in paleoclimate and paleoceanography, probably dominated by a major phase of Antarctic ice-cap growth.

  13. Mid-Miocene cooling and the extinction of tundra in continental Antarctica

    E-print Network

    Marchant, David R.

    Mid-Miocene cooling and the extinction of tundra in continental Antarctica Adam R. Lewisa of a tundra community that inhabited the mountains before stepped cooling that first brought a full polar of this global climate transition. climate change tundra biota Dry Valleys diatoms ostracods The Earth's climate

  14. EXTINCT PECCARY ``CYNORCA'' OCCIDENTALE (TAYASSUIDAE, TAYASSUINAE) FROM THE MIOCENE OF PANAMA AND

    E-print Network

    Bermingham, Eldredge

    EXTINCT PECCARY ``CYNORCA'' OCCIDENTALE (TAYASSUIDAE, TAYASSUINAE) FROM THE MIOCENE OF PANAMA and Archaeology, Smithsonian Tropical Research Institute, Balboa, Anco´n, Panama´, Republic of Panama´ ABSTRACT tayassuid) are described from new excavations along the southern reaches of the Panama Canal. Fossil

  15. NEW TURTLES (CHELONIA) FROM THE LATE EOCENE THROUGH LATE MIOCENE OF THE PANAMA CANAL BASIN

    E-print Network

    Bermingham, Eldredge

    NEW TURTLES (CHELONIA) FROM THE LATE EOCENE THROUGH LATE MIOCENE OF THE PANAMA CANAL BASIN EDWIN@ncsu.edu.; ,jbourque@flmnh.ufl.edu.; ,jbloch@flmnh.ufl.edu.; and 2 Smithsonian Tropical Research Institute, Panama, AA 34002- 0948, Panama, ,jaramilloc@si.edu. ABSTRACT--Four distinct fossil turtle assemblages (Chelonia

  16. Carbonate-evaporite cycles in the Miocene to Holocene of Abu Dhabi, United Arab Emirates

    Microsoft Academic Search

    G. L. Whittle; A. S. Alsharhan; H. Takezaki

    1995-01-01

    The coastal sabkhas of the United Arab Emirates provide a Holocene analog for the study of evaporite formation. Carbonate-evaporite sequences are common throughout geologic history and, in the Arabian Gulf region in particular, create the reservoir-seal relationship of some of the most prolific hydrocarbon reservoirs in the world. Detailed core description, thin section study and geochemical analysis of Miocene to

  17. Rapid late Miocene rise of the Bolivian Altiplano: Evidence for removal of mantle lithosphere

    Microsoft Academic Search

    Carmala N. Garzione; Peter Molnar; Julie C. Libarkin; Bruce J. MacFadden

    2006-01-01

    The oxygen isotopic compositions of carbonates deposited in the northern Altiplano demonstrate a rapid change in late Miocene time, which we attribute to an increase in elevation. Rainfall samples over an elevation transect adjacent to the Altiplano of northern Bolivia display a systematic decrease in mean annual ?18O values and define a local ?18O vs. altitude gradient [R. Gonfiantini, M.-A.

  18. Ocean Circulation and Gateway Closures During the Late Miocene (~13-5 Ma)

    Microsoft Academic Search

    S. A. Nathan; R. M. Leckie

    2004-01-01

    Long-term climate change is driven by tectonic influences, including changes in ocean circulation that are the result of ocean gateway closure. During the middle to late Miocene (~13-5 Ma), both tropical ocean circulation and deep water production were reorganized due to the increasing constriction of the Indonesian and Central American seaways. For example, the waters of the modern Pacific equatorial

  19. Late MiocenePliocene eclogite facies metamorphism, D'Entrecasteaux Islands, SE Papua New Guinea

    E-print Network

    Late Miocene­Pliocene eclogite facies metamorphism, D'Entrecasteaux Islands, SE Papua New Guinea B rapid, post 4 Myr exhumation and cooling of amphibolite and greenschist facies rocks that constitute and Goodenough Islands of the D'Entrecasteaux chain, the timing of eclogite facies metamorphism in rocks

  20. Late Miocene-Pliocene eclogite-facies metamorphism, D'Entrecasteaux Islands, SE Papua New Guinea

    E-print Network

    1 Late Miocene-Pliocene eclogite-facies metamorphism, D'Entrecasteaux Islands, SE Papua New Guinea of eclogite-facies metamorphism in rocks of the footwall had been unknown. Recent work revealed that at least interpretation that these U-Pb ages constrain zircon crystallization under eclogite-facies conditions within all

  1. Late Eocene to early Miocene ice sheet dynamics and the global carbon cycle

    Microsoft Academic Search

    C. H. Lear; Y. Rosenthal; H. K. Coxall; P. A. Wilson

    2004-01-01

    Paired benthic foraminiferal trace metal and stable isotope records have been constructed from equatorial Pacific Ocean Drilling Program Site 1218. The records include the two largest abrupt (<1 Myr) increases in the Cenozoic benthic oxygen isotope record: Oi-1 in the earliest Oligocene (?34 Ma) and Mi-1 in the earliest Miocene (?23 Ma). The paired Mg\\/Ca and oxygen isotope records are

  2. Enamel hypoplasia in Miocene rhinoceroses (Teleoceras) from Nebraska: evidence of severe physiological stress

    Microsoft Academic Search

    Alfred J. Mead

    1999-01-01

    Quarry samples of lower cheek teeth of the Miocene rhinoceros Teleoceras are analyzed for the presence of enamel hypoplasia using macroscopic, thin-section, and scanning electron microscopic techniques. The presence of enamel pits, furrows, and grooves is noted predominantly on, but not limited to, the buccal side of dp4s. The enamel defect is not as common on permanent teeth, but does

  3. Detrital geochronology and geochemistry of CretaceousEarly Miocene strata of Nepal: implications for timing and

    E-print Network

    Najman, Yani

    Detrital geochronology and geochemistry of Cretaceous­Early Miocene strata of Nepal: implications of the southern Lesser Himalayan zone of central Nepal. The Cretaceous­ Paleocene(?) Amile Formation is dominated documented by the U­Pb zircon ages. The fact that middle Eocene strata in Nepal were derived from

  4. Miocene faulting at plate tectonic velocity in the Himalaya of central Nepal

    E-print Network

    Miocene faulting at plate tectonic velocity in the Himalaya of central Nepal Matthew J. Kohna, Tri-Chandra Campus, Ghantaghar, Kathmandu, Nepal, United States Received 7 April 2004; received (MCT) and affiliated faults in central Nepal. Inferred rates were 1.5F0.9 cm/yr (Langtang Thrust, ~19

  5. A re-examination of Palaeostruthus hatcheri (Shufeldt), a late Miocene sparrow from kansas

    Microsoft Academic Search

    David W. Steadman

    1981-01-01

    Palaeostruthus hatcheri (Shufeldt), from the late Miocene (late Clarendonian-early Hemphillian) Long Island local fauna, Kansas, is the oldest recorded species of Emberizidae. The holotype and only specimen of P. hatcheri is a complete rostrum which, upon re-examination, is seen to be extremely similar to that of Ammodramus savannarum, the living grasshopper sparrow. Therefore, the genus Palaeostruthus Wetmore is synonymized with

  6. A new species of hippopotamus Hexaprotodon lothagamensis (Mammalia: Hippopotamidae) from the late Miocene of Kenya

    Microsoft Academic Search

    E. M. Weston

    2000-01-01

    A new small to medium-sized hippopotamus, Hexaprotodon lothagamensis is described from the late Miocene of northern Kenya. The material was recovered from Lothagam, a site southwest of Lake Turkana. This narrow-muzzled hippopotamus differs from other Hexaprotodon species in terms of its small size and shallow symphysis. The six incisors are arranged in a straight line across the front of the

  7. Petrologic study of a Miocene gabbro emplaced during initial rifting in the Red Sea 

    E-print Network

    Johnston, Beatrice Bryant

    1978-01-01

    supporting the pre- sence of the Afar plume. As crustal thinning and uplift continued into Miocene time from this "hot spot", alkaline flood basalts were erupted in Ethiopia, in the Afar depression, and on the As Sirat plateau. In this same time period...

  8. Early to Middle Miocene vegetation and climate of Wilkes Land, Antarctica (IODP 318)

    NASA Astrophysics Data System (ADS)

    Salzmann, U.; Sangiorgi, F.; Bijl, P. K.; Pross, J.; Schouten, S.; Tauxe, L.; Bendle, J.; Brinkhuis, H.; Escutia, C.; IODP Expedition 318 Science Party

    2012-04-01

    The question of whether continental Antarctic climate was warm enough to support a substantial vegetation cover during the Neogene is of great significance to the ongoing controversial debate on the behaviour of Antarctic land ice during the Miocene-Pliocene transition from dynamic to persistent ice sheets. Here we present palynological results from a Miocene sediment record provided by the Integrated Ocean Drilling Program (IODP) Expedition 318 to the Wilkes Land margin (East Antarctica). The reconstructed vegetation changes are compared with climate estimates derived from dinoflagellate cysts and MBT/CBT organic palaeotemperature proxies. Analyses of pollen and spores indicate a low-diverse vegetation dominated by Podocarpus- and Nothofagus- trees and shrubs. Particular high Podocarpus percentages occur during the Middle Miocene Climatic Optimum (MMCO). For this time period MBT/CBT suggests a cool temperate climate with increased mean air temperatures (MAT). Dinoflagellate cyst assemblages, dominated by autotrophic species, are indicative of ice-free surface waters. After MMCO a subsequent decline in MAT is indicated by MBT and dinoflagellate cyst assemblages, though pollen percentages (e.g. Podocarpus/Nothofagus ratio) remain relatively stable. However, very high Nothofagus and low Podocarpus pollen percentages may suggest lower temperatures towards the end of the middle Miocene.

  9. SHARKS AND RAYS (CHONDRICHTHYES, ELASMOBRANCHII) FROM THE LATE MIOCENE GATUN FORMATION OF PANAMA

    E-print Network

    Bermingham, Eldredge

    . MACFADDEN,1 AND CARLOS JARAMILLO2 1 Florida Museum of Natural History, University of Florida, Gainesville California Sur, AP 23080, Mexico, ,gerardo@uabcs.mx.; and 5 Alabama Museum of Natural History, University of Alabama, Tuscaloosa, Alabama, 35487, USA, ,djehret@ua.edu. ABSTRACT--The late Miocene Gatun Formation

  10. Calculations of sulfate diffusivity for lithofacies of the Miocene Monterey Formation

    Microsoft Academic Search

    D. A. Zaback; L. M. Pratt

    1991-01-01

    Integration of stable sulfur isotopic data, total sulfur content, uncompacted porosity, and estimated sediment density of the Miocene Monterey Formation have been used to calculate the extent of sulfate diffusion in the upper tens of centimeters of sediment during early diagenesis. Extent of sulfate diffusion, expressed as the number of pore volumes of water filtered through a volume of sediment,

  11. The Miocene avifauna of the Li Mae Long locality, Thailand: systematics and paleoecology

    NASA Astrophysics Data System (ADS)

    Cheneval, Jacques; Ginsburg, Léonard; Mourer-Chauvire, Cécile; Ratanasthien, Benjavun

    The Miocene avifauna from Li Mae Long includes an anhinga, a heron, a new species of lesser flamingo, Phoeniconaias siamensis n. sp., two Anatidae, a Phasianidae, three Rallidae, and a Strigidae. The landscape indicated by the mammalian and avian faunas corresponds to a large swampy depression, with probably saline or alkaline waters, surrounded by humid forests, under a warm climate.

  12. Antarctic environmental variability since the late Miocene: ODP Site 745, the East Kerguelen sediment drift

    E-print Network

    the middle of the Pliocene warm epoch (4.8^3.2 Ma). The deep flow forming the Kerguelen drift was stronger in revised form 1 April 2002; accepted 10 April 2002 Abstract Characterization of sediment from Ocean surrounding the timing of Miocene to present East Antarctic ice sheet stability and oceanic environmental

  13. Evidence for sediment fan deposition on outer Texas shelf during Miocene eustatic sea level highstands

    SciTech Connect

    Riese, W.C.; Olsen, R.S.; Rosen, R.N.

    1988-02-01

    Four types of data were reviewed in an attempt to clearly define the environments of deposition for reservoir sands in the Matagorda 668 field: well log curve shapes, seismic amplitude responses, micropaleontology, and thin section sedimentary petrology. All four lines of evidence support the interpretation that these lower Miocene sands were deposited as fan complexes.

  14. Style and age of late Oligocene-early Miocene deformation in the southern Stillwater Range, west central Nevada: Paleomagnetism, geochronology, and field relations

    USGS Publications Warehouse

    Hudson, Mark R.; John, David A.; Conrad, James E.; McKee, Edwin H.

    2000-01-01

    Paleomagnetic and geochronologic data combined with geologic mapping tightly restrict the timing and character of a late Oligocene to early Miocene episode of large magnitude extension in the southern Stillwater Range and adjacent regions of west central Nevada. The southern Stillwater Range was the site of an Oligocene to early Miocene volcanic center comprising (1) 28.3 to 24.3 Ma intracaldera ash flow tuffs, lava flows, and subjacent plutons associated with three calderas, (2) 24.8 to 20.7 Ma postcaldera silicic dikes and domes, and (3) unconformably overlying 15.3 to 13.0 Ma dacite to basalt lava flows, plugs, and dikes. The caldera-related tuffs, lava flows, and plutons were tilted 60°-70° either west or east during the initial period of Cenozoic deformation that accommodated over 100% extension. Directions of remanent magnetization obtained from these extrusive and intrusive, caldera-related rocks are strongly deflected from an expected Miocene direction in senses appropriate for their tilt. A mean direction for these rocks after tilt correction, however, suggests that they were also affected by a moderate (33.4° ± 11.8°) component of counterclockwise vertical axis rotation. Paleomagnetic data indicate that the episode of large tilting occurred during emplacement of 24.8 to 20.7 Ma postcaldera dikes and domes. In detail, an apparent decrease in rotation with decreasing age of individual, isotopically dated bodies of the postcaldera group indicates that most tilting occurred between 24.4 and 24.2 Ma. The onset of tilting immediately following after the final caldera eruptions suggests that the magmatism and deformation were linked. Deformation was not driven by magma buoyancy, however, because tilting equally affected the caldera systems of different ages, including their plutonic roots. It is more likely that regional extension was focused in the southern Stillwater Range due to magmatic warming and reduction of tensile strength of the brittle crust. Faults that accommodated deformation in the southern Stillwater Range initially dipped steeply and cut deeply to expose more than 9 km of crustal section. The exposed crustal sections are probably rotated blocks above an unexposed basal detachment that lay near the early Miocene brittle-ductile transition.

  15. Stratigraphy and geochronology of the Comondú Group near Loreto, Baja California sur, Mexico

    Microsoft Academic Search

    Paul J Umhoefer; Rebecca J Dorsey; Shawn Willsey; Larry Mayer; Paul Renne

    2001-01-01

    Upper Oligocene to Middle Miocene volcanic and sedimentary rocks in the Loreto region, Baja California Sur, are widely exposed and make up the Comondú Group as redefined here following McFall. The Comondú Group is part of a volcanic arc and forearc basin that formed along the northwestern margin of Mexico. Regional to detailed scale mapping, stratigraphic analysis, and geochronology in

  16. Plate tectonic model for the oligo-miocene evolution of the western Mediterranean

    NASA Astrophysics Data System (ADS)

    Cohen, Curtis R.

    1980-10-01

    This paper outlines a plate tectonic model for the Oligo-Miocene evolution of the western Mediterranean which incorporates recent data from several tectonic domains (Corsica, Sardinia, the Kabylies, Balearic promontory, Iberia, Algero-Provençal Basin and Tunisian Atlas). Following late Mesozoic anticlockwise rotation of the Iberian peninsula (including the Balearic promontory and Sardinia), late Eocene collision occurred between the Kabylies and Balearic promontory forming a NE-trending suture with NW-tectonic polarity. As a result of continued convergence between the African and European plates, a polarity flip occurred and a southward-facing trench formed south of the Kabylie—Balearic promontory suture. During late Oligocene time an E-W-trending arc and marginal basin developed behind the southward-facing trench in the area of the present-day Gulf of Lion. Opening of this basin moved the Corsica—Sardinia—Calabria—Petit Kabylie—Menorca plate southward, relative to the African plate. Early Miocene back-arc spreading in the area between the Balearic promontory and Grand Kabylie emplaced the latter in northern Algeria and formed the South Balearic Basin. Coeval with early Miocene back-arc basin development, the N-S-extension in the Gulf of Lion marginal basin changed to a more NW-SE direction causing short-lived extension in the area of the present-day Valencia trough and a 30° anticlockwise rotation of the Corsica-Sardinia-Calabria—Petit Kabylie plate away from the European plate. Early—middle Miocene deformation along the western Italian and northeastern African continental margins resulted from this rotation. During the early late Miocene (Tortonian), spreading within a sphenochasm to the southwest of Sardinia resulted in the emplacement of Petit Kabylie in northeastern Algeria.

  17. Seismic-stratigraphic analysis of Miocene system, offshore Texas - models and implications

    SciTech Connect

    Riese, W.C.; Hill, W.A.; Rosen, R.N.

    1989-03-01

    The application of traditional seismic-stratigraphic models to the Miocene System offshore Texas was tested and found to be inadequate for the description of this section. Although the basic principles inherent to the application of seismic stratigraphy are useful, there are significant deviations from the model geometries of system tracts in the Miocene System. The most significant of these discrepancies is the apparent absence of lowstand wedges and shelf-margin wedges. Problems with applying the traditional seismic stratigraphic models and geometries to the interpretation of this section have been recognized by others, and alternative ramp and growth-fault models have been suggested. These, too, appear to be inadequately for interpretation of this section: the ramp model fails to account adequately for outer neritic bathymetries in apparent outer-shelf settings during lowstands; the growth-fault model fails to adequately explain downthrown expansion of predominantly shale intervals. The alternatives proposed postulate a fundamental difference in global, or at least basinal, water budgets for Miocene time relative to the Pleistocene or Holocene: eustatic levels in the Gulf of Mexico during the Miocene were apparently several hundred feet higher than during the Pleistocene and therefore erosion of the shelf during lowstands was minimal. The authors may also infer that surface gradients on the Texas shelf were steep during the Miocene and there was no pronounced continental shelf-slope break. Without such a break there is no steep surface against which to onlap the updip reaches of shelf-margin wedges or lowstand wedges, thus accounting for the absence of these geometries in their seismic data. this accounts for the presence of depositional fans in outer neritic, apparently shelfal settings during lowstands.

  18. Paleogeographic and structural setting of Miocene strata in central western Nevada

    SciTech Connect

    Stewart, J.H. (Geological Survey, Menlo Park, CA (United States))

    1993-04-01

    Late Cenozoic sedimentary rocks as old as 19 Ma are widely distributed in central western Nevada. They are greatly more abundant than older Cenozoic strata and are commonly interpreted to have formed in fault-bounded basins that mark the onset of widespread extension in the Basin and Range Province. Miocene strata are largely coeval with a magmatic arc that extended south southeast near the boundary of the Basin and Range and Sierra Nevada Provinces. This arc produced voluminous andesitic flows and lahars that locally interfinger with the Miocene strata. Miocene depositional basins apparently varied greatly in size. The largest that can be defined clearly is the Esmeralda Basin that was at least 65 km long and 45 km wide. Other basins may have been larger but are difficult to reconstruct; still other basins may be small and isolated, particularly within the magmatic arc. Lacustrine deposits and minor interfingering deltaic and distal fluvial units predominate; near-source, coarse alluvial-fan and megabreccia landslide deposits are locally conspicuous. coarse near-source deposits, particularly landslide deposits, are interpreted to be adjacent to basin-bounding normal faults. The Esmeralda, Coal Valley, and Gabbs Valley-Stewart Valley-Tonopah Basins are interpreted to be related to large-scale Miocene extension. Other basins may be (1) pull-apart structures related to strike-slip faults, (2) downdropped blocks in areas of cross-cutting normal and/or strike-slip faults related to changes in the extension direction or (3) grabens or half-grabens related to uniform extension. Younger Cenozoic basins, including present-day basins, overprint and cut across the Miocene basins.

  19. Contrasting accommodation zones linking Miocene-Pliocene basins in the Big Bend (West Texas)

    SciTech Connect

    Dickerson, P.W. (Univ. of Texas, Austin, TX (United States). Dept. of Geological Sciences)

    1992-01-01

    N-NW-trending Miocene-Pliocene basins of the Big Bend (West Texas) are linked or segmented by westerly to west-northwesterly accommodation zones of varying antiquity, relief and displacement. They are boundaries between basins of similar age but differing dimensions and geometries. All demonstrably predate Miocene-Pliocene extensional/transtensional deformation and foundering of the basins. Shafter zone, the northernmost, segments Presidio graben into a 20-km-wide north-trending subbasin and a 30-km-wide northwest-trending one to the south. Hot springs mark border fault-accommodation zone intersections. Vertical displacement there is 5 m. From 50 to 90 km still farther east Shafter zone defines the northern margins of two basins, northern Tornillo and Black Gap, which flank the Santiago range. Presidio zone intervenes between the 30-km-wide southern Presidio graben and the 10-km-wide Redford graben on the south. Early Miocene pre- and synmagmatic faulting occurred along Tascotal Mesa fault, the principal structure of the zone. Post-Early Miocene displacement has been dominantly vertical (as much as 100 m), accompanied by ca. 1 km of right slip. The west-northwesterly Colorado Canyon/Terlingua zone links Redford graben with Castolon graben and its southeastward continuation into Mexico. Fault displacement in this accommodation zone, as in the other two, is primarily vertical with evidence for more significant right slip. Small Miocene mafic bodies intrude the zone; some bear lower crustal or mantle xenoliths, attesting that the zone is a deeply rooted crustal flaw.

  20. Rifting, rotation, detachment faulting, and sedimentation: Miocene evolution of the southern California margin

    SciTech Connect

    Bachman, S.B.; Crouch, J.K. (Crouch, Bachman, and Associates, Inc., Santa Barbara, CA (USA))

    1990-05-01

    The evolution of the Los Angeles and adjacent offshore Santa Monica and San Pedro basins of southern California began during the earliest Miocene. The basins formed as the result of rifting and subsequent large scale rotation of segments within a preexisting Mesozoic-Paleogene forearc basin. Clockwise rotation (less than 90{degree}) of the outer two-thirds of this fore-arc basin during the early and middle Miocene moved these once north-trending forearc strata into an east-west trend (the modern Transverse Ranges). The eastern margin of the initial rift remains in its original location and is best documented from outcrop and subsurface data in the San Joaquin Hills. What was once the western margin of the rift has been rotated to a position north of the rift, along the southern Santa Monica Mountains. The early Miocene Vaqueros sandstones. which that are entirely shallow-marine and thousands of feet thick provide evidence for initial subsidence of the rift. Widening of the rift and separation of the Santa Monica Mountains and the San Joaquin Hills in the early and middle Miocene was accompanied by detachment faulting and volcanism along the rift margins. These detachment faults can be documented in the subsurface of the San Joaquin Hills and in outcrop in the Santa Monica Mountains. A unique aspect of this inner borderland rift is the rapid uplift, exposure, erosion, and then subsidence of high pressure/temperature metamorphic basement blocks (Catalina schist) within the rift itself. These basement rocks were buried 20 to 30 km beneath the ancestral fore arc prior to rifting. They were uplifted, perhaps due to thermal effects, during pervasive early and middle Miocene volcanism within the rift. Evidence of these dramatic events is provided by the distinctive San Onofre breccia deposit exposed along the margins of the rift.

  1. Depositional history of Oligocene-Miocene carbonate rocks of northeastern Puerto Rico

    SciTech Connect

    Scharlach, R. (Univ. of New Orleans, LA (USA))

    1990-05-01

    The apparent tectonic stability of the northern Puerto Rico platform during the late Oligocene and early Miocene allows for the depositional history of subsurface carbonate rocks of northeastern Puerto Rico to be related to major changes in eustatic sea level. During a late Oligocene north to south transgression of sea level, fluvial/deltaic to shallow marine terrigenous sediments (San Sebastian Formation) and, subsequently, open-ramp carbonates (Lares Limestone) accumulated in the central basin. Following a minor regression (third-order cycle ), a more extensive early Miocene( ) transgression resulted in deposition of deeper ramp carbonate mudstone and marl (Mudstone unit) in an apparent trough in the central basin, and open-ramp reefal carbonate (upper Lares) was deposited over a wider area of the basin. The San Sebastian Formation/Lares Limestone/Mudstone Unit sequence was most likely deposited during the second-order supercycle, TB{sub 1}. An early Miocene relative fall in sea level resulted in deposition of interfingering inner-ramp limestone and terrigenous sediments (Cibao Formation) and the development of subaerial costs, especially in the upper part of the unit. During a sea level rise, terrigenous deposition decreased and gave way to inner- and middle-ramp carbonate sediments (Los Puertos Limestone). A middle Miocene highstand in sea level brought basin-wide deposition of open-ramp carbonate sediments (Aymamon Ls). The Cibao Formation/Los Puertos Limestone/Aymamon. Limestone sequence may correspond to the second-order supercycle, TB{sub 2}. During the late middle Miocene( ), the carbonate platform was exposed and extensively karsted, possibly in an event related to the sea level drop at the end of TB{sub 2}.

  2. The giant bite of a new raptorial sperm whale from the Miocene epoch of Peru.

    PubMed

    Lambert, Olivier; Bianucci, Giovanni; Post, Klaas; de Muizon, Christian; Salas-Gismondi, Rodolfo; Urbina, Mario; Reumer, Jelle

    2010-07-01

    The modern giant sperm whale Physeter macrocephalus, one of the largest known predators, preys upon cephalopods at great depths. Lacking a functional upper dentition, it relies on suction for catching its prey; in contrast, several smaller Miocene sperm whales (Physeteroidea) have been interpreted as raptorial (versus suction) feeders, analogous to the modern killer whale Orcinus orca. Whereas very large physeteroid teeth have been discovered in various Miocene localities, associated diagnostic cranial remains have not been found so far. Here we report the discovery of a new giant sperm whale from the Middle Miocene of Peru (approximately 12-13 million years ago), Leviathan melvillei, described on the basis of a skull with teeth and mandible. With a 3-m-long head, very large upper and lower teeth (maximum diameter and length of 12 cm and greater than 36 cm, respectively), robust jaws and a temporal fossa considerably larger than in Physeter, this stem physeteroid represents one of the largest raptorial predators and, to our knowledge, the biggest tetrapod bite ever found. The appearance of gigantic raptorial sperm whales in the fossil record coincides with a phase of diversification and size-range increase of the baleen-bearing mysticetes in the Miocene. We propose that Leviathan fed mostly on high-energy content medium-size baleen whales. As a top predator, together with the contemporaneous giant shark Carcharocles megalodon, it probably had a profound impact on the structuring of Miocene marine communities. The development of a vast supracranial basin in Leviathan, extending on the rostrum as in Physeter, might indicate the presence of an enlarged spermaceti organ in the former that is not associated with deep diving or obligatory suction feeding. PMID:20596020

  3. The Oligocene-Miocene transition at the East Antarctic Wilkes Land margin: IODP Site 1356

    NASA Astrophysics Data System (ADS)

    Salabarnada, Ariadna; Escutia, Carlota; Nelson, Hans; Damuth, John E.; Jimenez-Espejo, Francisco

    2015-04-01

    IODP drilling in the flank of a levee deposit at continental rise Site U1356 recovered a thick section of Oligocene to upper Miocene sediments indicative of relatively deep water, sea ice -- influenced setting. Three main lithological units characterize the sediment record: 1) hemipelagic and bottom current deposition dominated during the late early to late Oligocene; 2) debris flows with interbedded turbidite deposits characterize sedimentation during late Oligocene to early Miocene; and 3) turbidite and hemipelagic sedimentation dominated during the early Miocene. The regional grid of multichannel seismic lines, provide a regional depositional context for the three units. Early to late Oligocene deposits record abyssal plain sedimentation under the influence of bottom currents. The sharp transition from abyssal plain facies to distal debris flows during the late Oligocene coincides with the deposition of large mass transport deposits at the base of the continental slope and erosion of large channels on the continental rise. The distal end of these mass transport deposits is recovered in our cores interbedded with levee turbidites from the nearby channel. The Oligocene to Miocene transition marks the disappearance of debris flows in our cores and the start of turbidite and hemipelagic deposition that characterizes levee sedimentation of the early Miocene environment. The studied section records one of the major climate transitions in the history of Earth's climate and ice sheet evolution during leading to the Mi-1 event. We argue that mass transport processes resulted from East Antarctic Ice Sheet expansion during the climate cooling leading to the Mi-1 glaciation. Following the Mi-1 event, sedimentation is characterized by hemipelagic, turbidity-, and bottom-current deposition. In addition, we present elemental and clay mineralogy data that provide insights into terrigenous fluxes, productivity, and the transition from a poorly oxygenated low-silica system to a ventilated silica-enriched system that is more similar to the modern Southern Ocean.

  4. Seawater osmium isotope evidence for a middle Miocene flood basalt event in ferromanganese crust records

    USGS Publications Warehouse

    Klemm, V.; Frank, M.; Levasseur, S.; Halliday, A.N.; Hein, J.R.

    2008-01-01

    Three ferromanganese crusts from the northeast, northwest and central Atlantic were re-dated using osmium (Os) isotope stratigraphy and yield ages from middle Miocene to the present. The three Os isotope records do not show evidence for growth hiatuses. The reconstructed Os isotope-based growth rates for the sections older than 10??Ma are higher than those determined previously by the combined beryllium isotope (10Be/9Be) and cobalt (Co) constant-flux methods, which results in a decrease in the maximum age of each crust. This re-dating does not lead to significant changes to the interpretation of previously determined radiogenic isotope neodymium, lead (Nd, Pb) time series because the variability of these isotopes was very small in the records of the three crusts prior to 10??Ma. The Os isotope record of the central Atlantic crust shows a pronounced minimum during the middle Miocene between 15 and 12??Ma, similar to a minimum previously observed in two ferromanganese crusts from the central Pacific. For the other two Atlantic crusts, the Os isotope records and their calibration to the global seawater curve for the middle Miocene are either more uncertain or too short and thus do not allow for a reliable identification of an isotopic minimum. Similar to pronounced minima reported previously for the Cretaceous/Tertiary and Eocene/Oligocene boundaries, possible interpretations for the newly identified middle Miocene Os isotope minimum include changes in weathering intensity and/or a meteorite impact coinciding with the formation of the No??rdlinger Ries Crater. It is suggested that the eruption and weathering of the Columbia River flood basalts provided a significant amount of the unradiogenic Os required to produce the middle Miocene minimum. ?? 2008 Elsevier B.V.

  5. Interim report on the ground-water resources of Manatee County, Florida

    USGS Publications Warehouse

    Peek, Harry M.; Anders, Robert B.

    1955-01-01

    Manatee County comprises an area of about 800 square miles adjacent to the Gulf of Mexico in the southwestern part of the Florida peninsula. The county is underlain at depths ranging from about 200 to 350 feet by a series of limestone formations of Tertiary age having a total thickness of several thousand feet. The upper part of the limestone section consists of the Ocala group of Eocene age, the Suwannee limestone of Oligocene age, and the Tampa formation of early Miocene age. These limestone formations are overlain by the Hawthorn formation of middle Miocene age which consists of interbedded clay, limestone, and sand. The Hawthorn is overlain by undifferentiated deposits of sand, limestone, and shell of Pliocene(?) and Pleistocene age that range in thickness from a few feet to about 75 feet.

  6. Absolute magnitude of the second-order middle to late Miocene sea-level fall, Marion Plateau, northeast Australia

    SciTech Connect

    Pigram, C.J.; Davies, P.J.; Feary, D.A.; Symonds, P.A. (Bureau of Mineral Resources, Canberra (Australia))

    1992-09-01

    The Miocene carbonate platform of the Marion Plateau in northeast Australia preserves an excellent record of sea-level fluctuations. The warm-water platform consists of an early to middle Miocene second-order highstand complex, whereas the late Miocene platform is a second-order lowstand complex. Analysis of the sea-level fall that led to this relation shows that the amplitude of this event was at least 180 m. Furthermore, the authors suggest a methodology for determining the amplitude of sea-level fluctuations based on measurement of sea-level falls in structurally simple parts of passive margins or in distal parts of foreland basins.

  7. Cementation in Oligo-Miocene non-tropical shelf limestones, Otway Basin, Australia

    NASA Astrophysics Data System (ADS)

    Nicolaides, Stelios

    1995-02-01

    The Oligocene to Miocene Heytesbury Group of the Otway Basin, southeastern Australia, is a non-tropical carbonate shelf succession. This subsurface stratigraphic succession consists of bioclastic grainstones to mudstones containing bryozoa, benthonic and planktonic foraminifera, echinoderms, brachiopods, and molluscs. The basal bryozoa-dominated Clifton Formation was deposited in relatively shallow waters. The overlying Gellibrand Marl, rich in planktonic foraminifera and bryozoa, formed under deep waters. The uppermost unit, benthonic foraminifera-dominated Port Campbell Limestone, was deposited in a moderately deep, middle shelf environment. Cementation is limited and includes: (1) scalenohedral calcite (non-luminescent to bright, Mn- and Fe-poor, in inter- and intraparticle porosity); (2) blocky equant calcite (dull, Mn- and Fe-rich, in interparticle porosity); (3) syntaxial calcite overgrowths on echinoderm particles (non/bright/dull-zoned); (4) euhedral dolomite (in the interparticle pore space of the Port Campbell Limestone); (5) bladed-prismatic calcite (ferroan, in planktonic foraminifera); (6) fibrous calcite (non-luminescent, in intraparticle porosity); and (7) glauconite and iron-oxides (only in intraparticle porosity). All CaCO 3 cements are low-Mg calcites (< 4 mol% MgCO 3). The cements observed in the Heytesbury Group appear to have formed in three successive diagenetic environments: (1) early shallow burial (early Fe- and Mn-poor, non-luminescent syntaxial overgrowths and non-luminescent scalenohedral calcite, under oxidising conditions); (2) late shallow burial (bright, more Mn-rich syntaxial overgrowth zone, i.e., more than the initial non-luminescent one, and bright scalenohedral calcite, under moderately reducing pore water conditions); and (3) moderate burial (ferroan, dull blocky calcite and dull syntaxial overgrowth zone, under reducing conditions). Pressure solution was the main cement-producing mechanism, although seawater and aragonite dissolution could account for the precipitation of the early non-luminescent cements. Scarcity of early interparticle cements may have been caused by the calcite-rich character of the original sediments. The ferroan dully luminescent blocky equant calcite and syntaxial overgrowths, typically interpreted to represent products of deep burial in ancient carbonate successions, are observed in the shallow-buried Port Campbell Limestone.

  8. Petrofacies and provenance of the Puente Formation (middle to upper Miocene), Los Angeles basin, southern California: Implications for rapid uplift and accumulation rates

    SciTech Connect

    Critelli, S. [Consiglio Nazionale delle Ricerche, Roges di Rende (Italy). Istituto di Ricerca per la Protezione Idrogeologica nell`Italia Meridionale ed Insulare; Rumelhart, P.E.; Ingersoll, R.V. [Univ. of California, Los Angeles, CA (United States). Dept. of Earth and Space Sciences

    1995-10-02

    The Peunte Formation is a Middle-Upper Miocene clastic unit lying unconformably on the Lower-Middle Miocene El Modeno Volcanics and Topanga Group, in the Los Angeles basin. The Puente Formation, about 3900 m thick, is composed of conglomerate, sandstone, and mudrock deposit;ed as a submarine fan at bathyal depths. Several intrabasinal discordances suggest tectonic activity during deposition. The succession consists of two main upward-thickening and -coarsening megacycles, reflecting submarine-fan progradation. The Puente Formation is characterized up-section by: (1) thin-bedded sandstone and shale (La Vida member) grading to thick-bedded sandstone and conglomerate (Soquel Member); and (2) thin-bedded mudrock and sandstone (Yorba Member) grading to thick- to very thick-bedded sandstone and conglomerate (Sycamore Canyon Member). There is consistent provenance signal in spite of complex transportation tectonics, responsible for opening of the Los Angeles Basin, and later transpressional processes, which are still active. Detailed provenance study of the Puente Formation and related units provides important constraints on paleogeographic and paleotectonic reconstructions of southern California basins and uplifts.

  9. An early Miocene age for a high-temperature event in gneisses from Zabargad Island (Red Sea, Egypt): mantle diapirism?

    E-print Network

    Demouchy, Sylvie

    An early Miocene age for a high-temperature event in gneisses from Zabargad Island (Red Sea, Egypt outcropping on Zabargad Island (Red Sea, Egypt). This island, though of limited size (& 4 km2 ), has an almost

  10. Processes of Late Cretaceous to Late Miocene episodic thrust-sheet translation in the Lycian Taurides, SW Turkey 

    E-print Network

    Collins, Allan S; Robertson, Alastair H F

    1998-01-01

    The Lycian Taurides of SW Turkey consist of an allochthonous Mesozoic passive margin succession that was episodically detached from its autochthon and translated southeastwards between latest Cretaceous to Late Miocene times. A combination...

  11. Post-Miocene Tectonics from Black Sea to Mediterrenean Sea along Central Anatolian Plateau

    NASA Astrophysics Data System (ADS)

    Rojay, B.; Özsay?n, E.; Çiner, A.

    2012-04-01

    The existences of the gross structures are crucial elements in the understanding of the Neogene evolution of the Anatolia. The structures, from north to south, are fairly documented extensional Black Sea coast structures, "N vergent tectonics" in Black Sea region, the cross cutting scar/shear zone -North Anatolian Fault- , S verging tectonics in central Anatolian overthrust belt (Cretaceous ophiolitic mélange belt), extensional Tuzgölü basin, basins like Cilicia, Mut situated to the back of the Cyprian arc and Cyprus locked subduction and accretionary tectonics (locked by approaching and colliding of the Eratosthenes and Hecatacus "seamount" obstacles). The closure of the northern Neotethys during post-Late Eocene- pre-Miocene end with the collision of the squeezed "Anatolian Block" from south with the Eurasian Continent. Consequently the linkage of the central Anatolian basins is lost with the Seas (Paratethys) in north by the evolution of Black Sea Mountains. However, the subduction in southern Neotethys continued with a complex array due to oblique subduction between "Anatolian Block" and downgoing African-Arabian plates. The growth of the accretionary wedge along southeast Anatolia resulted in retreat of the Miocene Seas towards Basra Bay (Iraq) and collision of the southeast Anatolian belt operated to the end of late Miocene where the marine realm in eastern Mediterrenean Sea continues. The rifting - sea-floor spreading in Red Sea, propagating of Dead Sea Transform to the north and oblique subduction in southern Tethys Ocean during different times in Miocene-Pliocene manifested a various different tectonic mechanism stories in the evolution of the Neogene basin in Anatolia. Consequently progressive closure of the Tethys Oceans resulted in the development Central Anatolian and Eastern Anatolian Plateaus. The growth of the Plateaus, in other words, the progressive shortening from north to south during Late Miocene, ended with the escape of the Anatolian Block to the west during Pliocene as a result of the initiation of the North and East Anatolian Faults. The escape can be caused by the retreat of downgoing slab or enlargement of downgoing slab window or solely initiation of the North and East Anatolian faults as single shears or all. The escape was resulted in the NW-SE to NE-SW multi oriented extension in central Anatolian Plateau (from Ankara to Tuzgölü lake to Mut region) between North Anatolian in north and Cyprus in south. To sum up, the regions between the seismogenic North Anatolian Fault in north and Kirenia of northern Cyprus in south experience an extension since Pliocene. Key words: uplift, plateau evolution, locked subduction, Miocene, Anatolia.

  12. Orbitally paced phosphogenesis in Mediterranean shallow marine carbonates during the middle Miocene Monterey event

    NASA Astrophysics Data System (ADS)

    Auer, Gerald; Hauzenberger, Christoph A.; Reuter, Markus; Piller, Werner E.

    2015-04-01

    During the Oligo-Miocene major phases of phosphogenesis occurred in the Earth's oceans. Particularly in the Mediterranean region phosphate-rich sediments are well-known during this time. However, most phosphate-rich beds represent condensed or allochthonous hemipelagic deposits, formed by a complex interplay of physical and chemical enrichment processes. These underlying processes limit the application of these records for the study of a possible Milankovitch-scale climate control on Miocene phosphogenesis. In this regard the middle Miocene "Monterey event" is of particular interest, as it represents a documented phase of phosphogenesis coupled with a prominent carbon isotope excursion containing nine orbitally paced carbon isotope maxima (CM-events). The Oligo-Miocene shallow marine Decontra section located on the Maiella Platform (central Apennines, Italy), is a widely continuous carbonate succession in a mostly outer to middle neritic setting. Of particular interest are the well-winnowed grain- to packstones of the Middle Miocene Bryozoan Limestone, were occurrences of authigenic phosphate grains coincide with the Monterey event. The depositional setting of the Bryozoan Limestone allows to resolve the influence of orbital forcing on phosphogenesis, within a bio-, chemo- and cyclostratigraphically constrained stratigraphic model. LA-ICP-MS analyses revealed a significant enrichment of Uranium in the studied authigenic phosphate grains compared to the surrounding carbonate sediment. Notably, the Uranium enrichment allowed the use of natural gamma radiation (GR) as a proxy for the qualitative estimation of autochthonous phosphate content within the section, based on the absence of any other major gamma ray sources within the sediment. Time series analyses of high-resolution GR data indicate a strong influence of the 405kyr long-eccentricity cycle on natural gamma radiation in the Bryozoan Limestone. Our results link maxima in the GR record and thus phosphate content to orbitally paced increases in the burial of organic carbon, particularly during the CM-events of the "Monterey event". Thus, phosphogenesis during the middle Miocene in the Mediterranean was consequently controlled by the 405-kyr-eccentricity and its influence on large-scale paleoproductivity patterns in the Mediterranean.

  13. The role of CO2 in modulating Miocene climate and ice volume (Invited)

    NASA Astrophysics Data System (ADS)

    Greenop, R.; Sosdian, S. M.; Lear, C. H.; Foster, G. L.; Wilson, P.

    2013-12-01

    The Neogene period is characterised by long term cooling interrupted by a number of prominent warming events, for example the Middle Miocene climate optimum (MCO), an interval of global warmth, that was followed by the Mid-Miocene climate transition (MMCT), a step cooling superimposed on the long-term climate trend. Several Antarctic climate records suggest that the East Antarctic ice sheet was dynamic during the early Miocene (Lewis et al., 2006, Passchier et al., 2011). However, the output from ice sheet modeling experiments suggest that once large ice sheets have grown on East Antarctica they are inherently stable and consequently relatively high levels of CO2 are needed in order to initiate a deglaciation (~1000 ppm; Pollard and DeConto 2005). Over the past 5 years or so an increasing number of studies have illustrated that atmospheric CO2 was much more variable during the Miocene than previously thought, although the magnitude of CO2 change remains much smaller than anticipated by the ice sheet models (Foster et al., 2012, Kurshner et al., 2008, Zhang et al., 2013). Here we will draw together ?11B-pCO2 records, both new published, to evaluate the role of CO2 in modulating Miocene climate. Calculated ?11B-CO2 spanning 5-23 Ma from ODP Sites 926 and 872 are in broad agreement with the other recently published alkenone CO2 records despite the limitations of ?11B based CO2 reconstruction over these long timescales (e.g. variable ?11B of seawater) (Sosdian et al. 2013). We will also present high-temporal resolution boron isotope records from ODP Site 761 across the MCO and ODP Site 926 across the Oligocene-Miocene boundary. We examine the role of CO2 in controlling the stability of the East Antarctic ice sheet during these short time intervals thought to be characterised by substantial retreat of the AIS (Feakins et al. 2012, Passchier et al. 2011, Warny et al. 2009). References: Feakins et al. (2012) Nat. Geoscience 5(8) 557-560, Foster et al., (2012) ESPL 341 243-254, Lewis et al., (2006) Geology 34(7) 513-516, Kurshner et al., (2008) PNAS 105(2) 449-453, Passchier et al., (2011) Geol Soc Am Bull, 123(11-12), 2352-2365, Pollard & DeConto (2005) Global and Planetary Change 45(1-3) 9-21, Sosdian et al. (2013) ICP11 abstract no. 161, Warny et al. (2009) Geology 37(10) 955-958, Zhang et al., (2013) in press, Phil. Trans. R. Soc. A

  14. Miocene sand distribution of the South Marsh Island and the Vermillion area, offshore Louisiana, Gulf of Mexico 

    E-print Network

    Kim, Jingoo

    1997-01-01

    MIOCENE SAND DISTRIBUTION OF THE SOUTH MARSH ISLAND AND THE VERMILION AREA, OFFSHORE LOUISIANA, GULF OF MEXICO A Thesis by JINGOO KIM Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment... 1997 Major Subject: Oceanography ABSTRACT Miocene Sand Distribution of the South Marsh Island and the Vermilion Area, Offshore Louisiana, Gulf of Mexico. (August 1997) Jingoo Kim, B. S. , Yonsei University Chair of Advisory Committee: Dr. Joel S...

  15. The first fossil leptofoenine wasp (Hymenoptera, Pteromalidae): A new species of Leptofoenus in Miocene amber from the Dominican Republic

    E-print Network

    Engel, Michael S.

    2009-06-30

    Th e fi rst fossil leptofoenine wasp (Hymenoptera, Pteromalidae): A new species of Leptofoenus 57 The first fossil leptofoenine wasp (Hymenoptera, Pteromalidae): A new species of Leptofoenus in Miocene amber from the Dominican Republic Michael S... fossil leptofoenine wasp (Hymenoptera, Pteromalidae): A new species of Leptofoenus in Miocene amber from the Dominican Republic. ZooKeys 13: 57-66. doi: 10.3897/zookeys.13.159 Abstract Th e fi rst fossil of the pteromalid subfamily Leptofoeninae...

  16. Seismic facies and growth history of Miocene carbonate platforms, Wonocolo Formation, North Madura area, East Java Basin, Indonesia 

    E-print Network

    Adhyaksawan, Rahadian

    2002-01-01

    SEISMIC FACIES AND GROWTH HISTORY OF MIOCENE CARBONATE PLATFORMS, WONOCOLO FORMATION, NORTH MADURA AREA, EAST JAVA BASIN, INDONESIA A Thesis by RAHADIAN ADHYAKSAWAN Submitted to the Office of Graduate Studies of Texas A&M University... in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE December 2002 Major Subject: Geophysics SEISMIC FACIES AND GROWTH HISTORY OF MIOCENE CARBONATE PLATFORMS, WONOCOLO FORMATION, NORTH MADURA AREA, EAST JAVA BASIN, INDONESIA...

  17. Miocene–Pleistocene tectono-sedimentary evolution of Bah??a Concepción region, Baja California Sur (México)

    Microsoft Academic Search

    J. Ledesma-Vázquez; Markes E Johnson

    2001-01-01

    Bah??a Concepción is one of the largest fault-bound bays in the Gulf of California. It is one of the area's best examples of an extensional basin, and an accommodation zone related to the Late Miocene extension in the Gulf of California region.Extensional tectonics in the Gulf region initiated from middle to early Late Miocene, in a simple east–west manner. The

  18. Lower Miocene (Upper Ottnangian) sands in the Lower Austrian Molasse Basin

    NASA Astrophysics Data System (ADS)

    Palzer, Markus; Knierzinger, Wolfgang; Wagreich, Michael; Gier, Susanne; Meszar, Maria Elisabeth; Soliman, Ali

    2015-04-01

    In the Early Miocene (late Ottnangian), a global sea level drop and the continuous rise of the Alps lead to the regression of the Parathethys sea, and to the sedimentation of the Upper Freshwater Molasse. In the Lower Austrian Molasse Basin, this event is represented by yellowish-brownish to greyish white mica-rich and carbonate-free sands and silts with clayish interlayers, formerly called Oncophora Beds (OB), which crop out between St. Pölten and Tulln. A new lithostratigraphy combines these sediments, now called Traisen-Formation (TF) together with the Dietersdorf Formation within the Pixendorf Group. Drill cores from OMV-wells predominantly from the NE show hundreds of meters thick sequences of pelites with intersections of sands interpreted as representing the OB. Contrary to the mainly brackish TF, a turbiditic marine deeper-water environment is inferred. An OMV-funded project investigates the relationship between these sediments, their stratigraphical and chronological range, provenance, facies and internal stratigraphy. First results from outcrops and several wells in the NE confirm large differences in grain size, structures and carbonate content. XRD-results indicate quartz, feldspar, muscovite, chlorite, calcite and dolomite as the main minerals within the sands and pelites. Pyrite is frequent. Halite and kaolinite occur. Whole rock chemistry, carbonate content measurements and biostratigraphic investigations of samples from the Wildendürnbach K4 well indicate, that these turbiditic OB can be divided into two sections: A lower fossil-free, carbonate poor and probably brackish (indicated by B/Al* and TOC/S) section with only few turbiditic very fine sands, and an upper microfossil bearing, marine section with carbonate contents up to 30% and more and coarser turbiditic sands. Therefore we use the working terms Lower and Upper Wildendürnbach Member (LWM, UWM). The lower part is enriched in (redox sensitive) heavy minerals such as Ce, Co, Cr, Cu, Gd, Ni, Pb, Sc, Zn and REE. It shows much lower constant Sr (about 140 ppm) values and B/Al* ratios (about 80) than the upper part (150 - 250 ppm; >120). The TOC/S ratio is much higher (17-23) in the LWM than in the UWM (>5). These two members can be correlated quite well by SP-logs over several wells. Therefore it can be concluded, that the lower part represents a period of salinity and carbonate crisis which may correspond to an (more or less) isolated deep basin probably poor in oxygen. At the beginning of the upper interval, a connection with the open sea was reestablished.

  19. Absolute Paleointensity Study of Miocene Tiva Canyon Tuff, Yucca Mountain, Nevada

    NASA Astrophysics Data System (ADS)

    Patiman, A.; Bowles, J.

    2014-12-01

    Unoriented samples from the ~12.7 Ma Tiva Canyon (TC) tuff from Yucca Mountain, Nevada are studied in terms of magnetic properties and geomagnetic paleointensity. The magnetic mineralogy and magnetic properties of the TC tuff have previously been well documented, and the remanence-carrier in ~15-m thick zones at the top and bottom of the unit is dominantly is single domain (SD) to superparamagnetic (SP) magnetite, which may be considered ideal for absolute paleointensity studies. Among one of the several episodic volcanic eruptions of the Southwestern Nevada Volcanic Field (SWNVF), the welded TC tuff belongs to the Paintbrush Group. Here we present magnetic properties from two previously unreported sections of the TC tuff, as well as Thellier-type absolute paleointensity estimates. Samples were collected from the lower ~7 m at the base of the flow. Magnetic properties studied include hysteresis, bulk magnetic susceptibility, frequency-dependent susceptibility, and anhysteretic remanent magnetization acquisition. Magnetic property results are consistent with earlier work, showing that the main magnetic mineral is magnetite. SP samples are dominant from the lower ~1 m to ~3.6 m basal unit while the middle unit of ~3.7 m to 7.0 m mainly consists of SD samples. The paleointensity results are closely tied to the stratigraphic height and magnetic properties linked to domain state. The SD samples have consistent absolute paleointensity values 32.40±0.22 uT, VADM 5.74*1022 A.m2 and behaved ideally during paleointensity experiments. The SP samples have consistently higher paleointensity and less ideal behavior, but would likely pass many traditional quality-control tests. Since the magnetite has been interpreted to form by precipitation out of the glass post-emplacement, but at temperatures higher than the Curie temperature, we tentatively interpret the SD remanence to be a primary thermal remanent magnetization and the paleointensity result to be a valid estimate of geomagnetic paleointensity for the Miocene. Post-emplacement vapor-phase alteration might be expected to alter magnetic mineralogy and magnetization, and has been reported in the upper portions of the TC tuff, but not in the lower sections discussed here.

  20. Middle-Miocene counterclockwise rotation of rocks from west-central Nevada; implications for Basin and Range extension

    SciTech Connect

    Hudson, M.R.; Geissman, J.W.

    1985-01-01

    Drilling and geophysical data from Dixie Valley and Fallon Basin of west-central Nevada have shown that dip-slip normal faults accommodated post-Miocene Basin and Range extension in this area, but the presence of an earlier, less-understood phase of Basin and Range deformation is suggested in the adjacent West Humboldt, Stillwater, and Clan Alpine Ranges where the late-Miocene basalts lie in angular unconformity on Oligocene to early-Miocene ash-flow tuffs. Paleomagnetic components obtained from the tuffs and underlying gabbroic and basaltic rocks of the Jurassic Humboldt Lopolith have declinations that are statistically different and counterclockwise from the expected Oligo-Miocene and Jurassic directions for the area. Paleomagnetic components from the late-Miocene basalts statistically overlap their expected direction. These data imply that the rocks were rotated counterclockwise during middle-Miocene. The common association of such rotations with strike-slip faulting suggests that this earlier phase of Basin and Range extension was largely a strike-slip faulting deformation. If so, the total amount of extension in the area may be significantly larger than estimates based solely on the moderate tilts (<30/sup 0/) of the ranges.

  1. A simple petrogenetic model for the formation of Miocene Low-?18O rhyolites of the Yellowstone Hotspot track, USA

    NASA Astrophysics Data System (ADS)

    Boroughs, S.; Wolff, J. A.; Starkel, W. A.

    2012-12-01

    The inland northwest of the United States contains a large intraplate igneous province that was initiated at ~16.6 Ma and is still active at the present. Its products include the Miocene Columbia River Basalt Group (CRBG), Miocene to Quaternary basalts and rhyolites of the High Lava Plains and the Snake River Plain, and the Quaternary Yellowstone volcanic plateau. The total volume of magma produced is uncertain, but approximately 2.5 x 105 km3 of basalts were erupted during the first million years of activity; applying magma supply rates calculated for the Snake River Plain, the total volume of mantle-derived basalt represented by the entire province may be twice that figure. Snake River Plain rhyolites are notable for the abundance of 18O-depleted units (<6‰) compared to most volcanic rocks on Earth. Low-?18O rhyolitic magma requires a source component that has exchanged oxygen at high temperatures with surface derived meteoric fluids; the degree of 18O-depletion seen in Snake River Plain rhyolites therefore requires a dominant proportion of meteoric-hydrothermally altered shallow crust among their source materials. No previous modeling has attempted to simultaneously satisfy constraints from O, Nd, Pb, and Sr isotopes for both rhyolites and basalts of the Snake River Plain using unmodified end member compositions from real surface samples. Any model for low ?18O Snake River Plain rhyolites must first account for O isotopes, because oxygen is ~50% of any silicate rock. We avoid the assumption that the geochemical character of the Snake River Plain basalts is wholly inherited from the mantle. Instead, we choose crustal materials that are abundantly exposed in proximity to the province (i.e. Idaho Batholith granitoids) and basalts that are generally accepted as primitive mantle-derived compositions (i.e. Steens basalts). The influence of continental crust on the chemistry of hotspot eruptives has been well documented. We assume this as a starting point, and construct mass balance models in order to find the simplest possible explanation for the observed features of the Snake River Plain rhyolites. We show that, when the Yellowstone hotspot track including the Columbia River and Steens basalts is treated as a single province derived ultimately from a common mantle source, the isotope geochemistry of these lavas and tuffs can be explained to a first order by simple mixing of asthenosphere-derived basalt (10%-40%) and granitic crust of the Idaho batholith (60%-90%). This model is consistent with, but does not require, a stationary mantle plume as the origin of the province.

  2. Salt-dome-related diagenesis of Miocene sediment, Black Bayou field, Cameron Parish, Louisiana

    SciTech Connect

    Leger, W.R.

    1988-09-01

    The Black Bayou field is associated with a salt dome that pierces Miocene sediment and rises to within 900 ft (275 m) of the surface. The Louisiana Gulf Coast regional geothermal gradient is locally affected by the salt dome. The gradient increases to values greater than the regional gradient, 1.26/degrees/F/100 ft (23/degrees/C/km), near the dome. Local effects of the salt dome on clastic diagenesis have been determined by studying sandstone samples adjacent to and away from the salt dome within Miocene sediment. Sample depths range from 4155 to 6145 ft (1266 to 1873 m). Distances of samples from the edge of the dome range from 82 to 820 ft (25 to 250 m).

  3. Depositional and structural evolution of the Middle Miocene depositional episode, east-central Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Combellas Bigott, Ricardo Ignacio

    Two widespread, transgressive deposits associated with the faunal top Amphistegina B (15.5 Ma) and Textularia W (12.1 Ma) define the Middle Miocene depositional episode. An extensive stratigraphic correlation framework established in this study allowed tracing of the middle Miocene sediment dispersal system from the shelf through the slope to the basin floor in the complex paleogeography of the east-central Gulf of Mexico. The Middle Miocene depositional episode is recorded in four genetic cycles (˜1 to 2 Ma), bounded by regional maximum flooding surfaces in the shelf and shelf margin setting, and three equivalent seismic sequences punctuated by condensed sections in the slope and basin floor. Two principal, long-lived extrabasinal fluvial/delta axes, the ancestral Mississippi and the Tennessee systems, provided the bulk of sediments that infilled the middle Miocene depocenters. Salt-related structural provinces controlled the configuration of the depocenters. Structural linked systems, dominated by gravity spreading, and a minibasin province, driven by differential subsidence, were established during the Middle Miocene depositional episode. Sediment supply coupled with wave energy flux, high-frequency sea-level changes, and salt tectonism determined the time and space distribution of progradation, aggradation, and retrogradation of system tracts. Middle Miocene shelf margins have prograded 20 to 40 miles from the relict lower Miocene shelf margin. Two depositional systems tracts characterize the constructional shelf margin: (1) a mixed-load fluvial-dominated platform delta/shelf-margin delta/delta-fed apron systems tract; and (2) a strandplain/shelf/muddy slope systems tract. However, the constructional, offlapping shelf margin systems were locally punctuated by a large-scale phase of retreat and erosion, named the Harang collapse system, in which a large volume of sediments bypassed the shelf margin to be deposited on the slope and basin floor. The Harang collapse system is a type of large-scale slope failure produced by massive salt-withdrawal, retreat of major delta systems, and high-frequency sea-level fluctuations. A large volume of sediment bypassed the confined minibasin province and the unconfined Florida slope at the flank of active deltaic depocenters, forming the long-lived MCAVLU submarine fan system (named for its location beneath the Mississippi Canyon, Atwater Valley, and Lund continental shelf (OCS areas) in the linked, primary minibasin corridor of the lower slope and basin floor. The MCAVLU submarine fan system evolved from a structurally-controlled, elongate sand-rich to mixed sand/mud fan to a large radial, mixed sand/mud fan. Significant untapped middle Miocene hydrocarbon resources remain in the confined channel fills and lobes of the Harang collapse system and sand-rich ponded facies assemblages of the MCAVLU submarine fan system.

  4. REE geochemistry of late Miocene lavas from Pioneertown, Fry Mountain and Ruby Mountain, California

    SciTech Connect

    Mehegan, J.M.; Thorpe, R. (California State Univ., San Bernardino, CA (United States))

    1993-04-01

    A series of flows, dikes and cinder cones of alkaline and subalkaline basalts erupted in late Miocene time along the northeastern flank of the San Bernardino Mountains and in contiguous parts of the Mojave Desert. Previous studies of lavas from the region yielded K-Ar ages of 6 to 9 Ma, and reported that lavas from the Ruby Mountain locality often contain ultramafic inclusions of probable mantle origin. This study (1) characterizes the rare earth element (REE; light = LREE; heavy = HREE) and trace element compositions of the young lavas from this region, (2) discusses the relationship of the Pioneertown lavas with the hot-spring ( ) deposits stratigraphically beneath the lava flows, (3) speculates on the possible volcanic conduit for the Pioneertown lavas, and (4) discusses the petrogenesis of these late Miocene lavas.

  5. Palynology of the Heath Formation (Miocene) from the Progreso Basin, Peru

    SciTech Connect

    Engelhardt, D.W. (Univ. of South Carolina, Columbia (United States)); Wood, G.D. (Amoco Production Co., Houston, TX (United States))

    1993-02-01

    A diverse and well preserved assemblage of pollen, spores, dinoflagellates, and acritarchs were recovered from outcrop samples of the Heath Formation, exposed along Bocapan Creek near Tumbes, Peru. The pollen and spores include representatives of Arecipites, Bombacacidites, Caryapollenites, Cicatricosisporites, Couperipollis, Cyathidites, Diporisporites, Distaverrusporites, Dyadosporites, Echiperiporites, Faramea, Foveodiporites, Foveotriletes, Fusiformisporites, Gothanipollis, Granitricolpites, Hymenophyllum, Hexpollenties, Involutisporites, Laevigatosporites, Lygodiumsporites, Magniperiporites, Malvacearumpollis, Monocolpopollenites, Perissyncolporites, Peritheciumites, Phragmothyrites, Polyadadporites, Polypodiaceisporites, Polypodiisporites, Retibrevitricolpites, Striadisporites, Tetracolporites, Tricolporopollenties, and Verrucosisporites. Plankton are assignable to Lejeunecysta, Operculodinium, Pterospermella, Selenopemphix, Spiniferites, Sumatradinium, Tythodiscus, and Tuberculodinium. The palynomorph assemblage can be placed in the Early Miocene based on the co-occurrence of Cicatricosisporites dorogensis, Couperipollis rarispinosus, Echiperiporites estelae, Magniperiporites echinatus, Perisyncolporites porkornii, Polypodiaceoisporites minor, P. potoniei, Reticolporites guianesnsis, R. irregularis, Scabriporites asymetricus, Selenopemphix nephroides and Tuberculodinium vancampoae. This is an agreement with foraminiferal evidence which positions the Heath Formation in the Early Miocene Catapsydrax dissimilis, Catapsydrax stainforthi and oldest portion of the Globigerinatella insueta zones.

  6. Sensitivity of climate and Atlantic overturning circulation to uncertain ocean gateway configurations for the late Miocene

    NASA Astrophysics Data System (ADS)

    Bradshaw, C.; Lunt, D. J.; Flecker, R.; Martinez-Mendez, G.

    2013-12-01

    The palaeorecord documents late Miocene (11.6-5.3 Ma) climate to be much warmer and wetter than today yet CO2 reconstructions are similar to modern levels. Given the apparent decoupling between CO2 and warmth for this period we investigate here the role of the oceans. The late Miocene experienced significant tectonic change including the restriction of some of the last ocean gateways to close (Panama Gateway and Indonesian Seaway) and open (Bering Strait and Barents/Kara Sea). However, the timing and configuration of these tectonic changes is uncertain. The final closure of the Panama Gateway is dated to the Pliocene, but continental mammal exchange suggests the existence of a Central American archipelago from the mid-late Miocene. The Bering Strait is typically assumed to have opened at the very end of the late Miocene/early Pliocene based on diatom exchange, but other marine and terrestrial evidence points to a much earlier, perhaps intermittent, opening. The timing of the restriction of the Indonesian Seaway is very poorly constrained at middle Miocene to Pliocene. The Barents Sea and Kara Sea shelves are documented as having being subject to extensive glacial erosion and post-glacial uplift since the Pliocene and throughout the Quaternary but records of uplift and erosion during the earlier Cenozoic are limited. However, the presence of significant preglacial sediments suggests that this region underwent tectonic uplift, volcanism and subsequent erosion during the Eocene-Miocene period although the age assignment of the data remains controversial. The Panama Gateway has been suggested to influence North Atlantic Deep Water (NADW) production through numerous modelling studies, the Bering Strait has been suggested to greatly impact NADW during the Quaternary, and the strength of Indonesian Throughflow is hypothesised to influence Agulhas Leakage, which, in turn, has been speculated to influence Atlantic meridional overturning and thus NADW production. Here, we investigate how the opening and closing of these gateways might influence ocean circulation, and hence climate, with late Miocene boundary conditions using the fully coupled atmosphere-ocean-vegetation GCM HadCM3L with TRIFFID. We show how the model suggests these gateways in different configurations might influence NADW production, with results from all possible combinations of these three gateways presented and compared to the available proxy data. The climatic implications of the presence of the Barents Shelf and Kara Shelf land masses prior to their final erosion has not been the subject of much research, either through modelling or data interpretation, and indeed many model simulations for the Miocene do not include these shelves as land masses at all. Here we also test our hypothesis that these land masses also impact NADW production through the restriction of the exchange of water between the Arctic Ocean and the Greenland-Iceland-Norwegian Sea. We hypothesize that their presence as land masses results in a saltier North Atlantic than occurs after their erosion; without the land masses there, the North Atlantic would experience more influence from the East Greenland Current (colder/fresher) and less influence of the Irminger Current (warmer/saltier).

  7. Faunal change in the Turkana Basin during the late Oligocene and Miocene.

    PubMed

    Leakey, Meave; Grossman, Ari; Gutiérrez, Mercedes; Fleagle, John G

    2011-01-01

    Faunal evolution over the last 65 million years of earth's history was dominated by mammalian radiations, but much of this era is poorly represented in Africa. Mammals first appeared early in the Mesozoic, living alongside dinosaurs for millions of years, but it was not until the extinction of dinosaurs 65 myr ago that the first major explosion of mammalian taxa took place. The Cenozoic (65 Ma to Recent) witnessed repeated and dynamic events involving the radiation, evolution, and extinction of mammalian faunas. Two of these events, each marking the extinction of one diverse fauna and subsequent establishment of another equally diverse fauna, both involving advanced catarrhine primates, are recorded in sites in the Turkana Basin, despite the poorly represented record of Cenozoic faunas elsewhere in sub-Saharan Africa. The first of these events occurred at the Oligocene-Miocene transition and the other at the Miocene-Pliocene transition. PMID:22170693

  8. Late Miocene continental sedimentation in southwestern Amazonia and its regional significance: Biotic and geological evidence

    NASA Astrophysics Data System (ADS)

    Latrubesse, Edgardo M.; da Silva, Silane A. F.; Cozzuol, Mario; Absy, Maria Lúcia

    2007-01-01

    Fossil content (vertebrate paleofauna and palynology) indicates that the sediments of the Solimões Formation in Acre (SW Brazilian Amazonia) are continental, having been deposited by avulsive fluvial belts in a floodbasin-floodplain environment. The main source area was the Andes chain. Widespread lacustrine swampy deposits, stacked channel deposits, and paleosoils are typical elements that characterize the Solimões Formation sediments that outcrop in southwestern Brazilian Amazonia. New data on fossil vertebrate assemblages and palynology corroborate the Late Miocene age suggested previously and assign the fossils to the Huayquerian mammalian biozone, spanning 9-6.5 Ma. These geological and paleontological data show that the existence of an intracontinental seaway through SW Amazonia during the Late Miocene (11-10 Ma), connecting the Caribbean Sea with the Parana Basin as previously proposed is unsustainable, because the sediments used by previous authors to propose the seaway were deposited in a continental environment and are younger than 11-10 Ma.

  9. Basal Adare volcanics, Robertson Bay, North Victoria Land, Antarctica: Late Miocene intraplate basalts of subaqueous origin

    USGS Publications Warehouse

    Mortimer, N.; Dunlap, W.J.; Isaac, M.J.; Sutherland, R.P.; Faure, K.

    2007-01-01

    Late Cenozoic lavas and associated hyaloclastite breccias of the Adare volcanics (Hallett volcanic province) in Robertson Bay, North Victoria Land rest unconformably on Paleozoic greywackes. Abundant hyaloclastite breccias are confined to a paleovalley; their primary geological features, and the stable isotope ratios of secondary minerals, are consistent with eruption in a subaqueous environment with calcite formation probably involving seawater. In contrast, the lavas which stratigraphically overlie the hyaloclastites on Mayr Spur probably were erupted subaerially. K-Ar dating of eight samples from this basal sequence confirms the known older age limit (Late Miocene) of the Hallett volcanic province. Geochemical data reveal an ocean island basalt-like affinity, similar to other Cenozoic igneous rocks of the Hallett volcanic province. If a submarine eruptive paleoenvironment is accepted then there has been net tectonic or isostatic post-Late Miocene uplift of a few hundred metres in the Robertson Bay-Adare Peninsula area

  10. On the Possibility of Testing Miocene Clay from Cracow Area using Weight Sounding Test (WST)

    NASA Astrophysics Data System (ADS)

    Olesiak, Sebastian

    2014-03-01

    Polish standards concerning field investigation with the use of a Weight Sounding Test (WST) probe give interpretation of results for non-cohesive soils only. The lack of such interpretation for cohesive soils excludes this testing equipment from use. This paper presents the results of geotechnical site investigation and laboratory tests performed for Miocene clays in Carpathian Foredeep in the Cracow area. Based on the analysis of the results a correlation was determined between the characteristic values for the WST probe (number of half-turns NWST) and the selected properties of Miocene clays. The article is an attempt to create a complete interpretation of test results obtained for cohesive soil with WST equipment.

  11. Salt-dome-related diagenesis of Miocene sediment, Black Bayou field, Cameron Parish, Louisiana

    Microsoft Academic Search

    William R. Leger

    1988-01-01

    The Black Bayou field is associated with a salt dome that pierces Miocene sediment and rises to within 900 ft (275 m) of the surface. The Louisiana Gulf Coast regional geothermal gradient is locally affected by the salt dome. The gradient increases to values greater than the regional gradient, 1.26\\/degrees\\/F\\/100 ft (23\\/degrees\\/C\\/km), near the dome. Local effects of the salt

  12. Coeval formation of cataclasite and pseudotachylyte in a Miocene forearc granodiorite, southern Kyushu, Japan

    Microsoft Academic Search

    Olivier Fabbri; Aiming Lin; Hirotaka Tokushige

    2000-01-01

    Cataclastic rocks and pseudotachylytes are exposed along the Uchinoura shear zone, a normal fault zone cutting the middle Miocene (14 Ma) Osumi granodiorite in southern Kyushu, Japan. Cataclastic rocks include non-foliated clast-supported to matrix-supported cataclasite and foliated clast-supported cataclastic granodiorite. In these rocks, fracturing and comminution played a major role, but dissolution and recrystallization of quartz, and plastic deformation of

  13. A new Late Miocene hominoid from Kenya: Samburupithecus kiptalami gen. et sp. nov.

    NASA Astrophysics Data System (ADS)

    Ishida, Hidemi; Pickford, Martin

    1997-11-01

    A new genus and species of hominoid, Samburupithecus kiptalami, is erected on the basis of a maxillary specimen with complete post canine dentition. Its age is established as upper Miocene (9.5 Ma) on the basis of radioisotopic dating and associated mammalian fauna. The new genus is more closely related to the African ape —human clade (AAH) than is any other known extinct hominoid and it may well be on the line leading to hominids.

  14. A Miocene Forest Assemblage in the Columbia River Basalts of Washington State, USA

    NSDL National Science Digital Library

    This report describes a fossil locality in Washington State in which fossil trees are preserved standing upright in a Miocene basalt flow. Topics include the Columbia River Flood Basalts (one of which inundated the trees), a description of the fossil site, the ages of the basalt and the underlying clay, analyses of the fossil wood to determine tree species, and a discussion of the depositional environment in which the trees are preserved.

  15. An oreopithecid proximal humerus from the middle miocene of Maboko Island, Kenya

    Microsoft Academic Search

    Monte L. McCrossin

    1992-01-01

    A proximal humerus, recently recovered from the middle Miocene of Maboko Island, Kenya, provides the earliest evidence of\\u000a postcranial structure and adaptation of Oreopithecidae. Provisionally attributed toNyanzapithecus pickfordi (Harrison, 1986), the specimen manifests a globose head, subequally large tuberosities, and a board, shallow bicipital groove.\\u000a Although readily distinguished from the fundamentally cercopithecoid proximal humeral morphology ofVictoriapithecus (Senut, 1986), the Maboko

  16. Isotope analyses of molecular and total organic carbon from miocene sediments

    Microsoft Academic Search

    Mark Pagani; KATHERINE H. FREEMAN; MICHAEL A. ARTHUR

    2000-01-01

    Carbon-isotope compositions of n-alkanes, pristane and phytane, and total organic carbon were measured and compared against isotopic trends of coeval alkadienones from Miocene sediments containing very low organic-carbon contents. Compound-specific isotope analysis of n-alkanes and isoprenoid lipids, in conjunction with abundance distributions of n-alkanes reveal the influence of terrestrially derived organic carbon at all sites analyzed. In general, n-alkanes are

  17. Etisus evamuellerae, a new xanthid crab (Decapoda, Brachyura) from the Middle Miocene of Austria and Hungary

    PubMed Central

    Hyžný, M.; van Bakel, B.W.M.; Guinot, D.

    2015-01-01

    On the basis of several carapaces, a new species of xanthid crab, Etisus evamuellerae, is described from the Middle Miocene of the Vienna (Austria) and Great Hungarian basins. It differs from the coeval xanthids, Xantho moldavicus and Pilodius vulgaris, in having a distinctly protruding front and comparatively longer carapace. Contrary to those two species, the new one makes up for just a small percentage in the decapod crustacean assemblages studied. PMID:25983383

  18. Paleomagnetic evidence for Late Miocene counterclockwise rotation of north coast carbonate sequence, Puerto Rico

    SciTech Connect

    Reid, J.A.; Plumley, P.W. (Syracuse Univ., NY (United States)); Schellekens, J.H. (Univ. of Puerto Rico, Mayaguez (Puerto Rico))

    1991-03-01

    A paleomagnetic study of the essentially undeformed middle Tertiary carbonate sequence along the north coast of Puerto Rico reveals statistically significant pre-Pliocene discordance of characteristic component directions against those expected from cratonic North America for much of the section. Despite generally weak to moderately weak magnetic intensities, confirmation of the magnetization as primary in origin comes from the presence of two distinct components of magnetization, intrasite bipolarity, and/or the reproducibility of measurements. The mean geographic direction for the upper Oligocene to middle Miocene strata is 335.2{degree}/32.9{degree} and the corrected mean paleomagnetic pole is 207.6{degree}/66.5{degree}, (N = 3, {alpha}95 = 4.3{degree}). This suggests a counter-clockwise (CCW) block rotation of Puerto Rico and its microplate of 24.5{degrees} ({plus minus} 5.8{degrees}) during the late Miocene. Using a width of 250 km for the Northern Caribbean Plate Boundary Zone (NCPBZ) between the North American Plate and Caribbean Plate, the mean left lateral displacement implied is 1.8 to 2.4 cm/yr, which agrees fairly well with published relative motion rates for the two plates. Average rotation rate for 50 Ma to 20 Ma was 0.7{degree}/my but perhaps as great as 4{degree}/my in the Miocene. Resolution of mean paleolatitude indicates northward motion of a degree or less during the period of rotation. Causes of this short-lived rotation may include (1) tectonic escape from the inhibiting presence of the Bahama Banks and Beata Ridge during eastward motion of Puerto Rico along the sinistral transpressive Puerto Rico Trench and Muertos Trough fault systems or (2) changes in relative plate motions of the Caribbean and North American Plate during the late Miocene.

  19. Oligo-Miocene rift of Sardinia and the early history of the Western Mediterranean Basin

    Microsoft Academic Search

    A. Cherchi; L. Montadert

    1982-01-01

    The geodynamic evolution of the Western Mediterranean Basin, in spite of many studies, is still uncertain. There is some consensus for interpreting this basin as a kind of small oceanic marginal basin. Its opening has generally been related to a subduction process which was active during the Oligocene-Miocene somewhere east of Sardinia-Corsica1-7. As the margins of the basin are deeply

  20. A new chronology for the middle to late Miocene continental record in Spain

    Microsoft Academic Search

    W. Krijgsman; M. Garcés; C. G. Langereis; R. Daams; J. van Dam; A. J. van der Meulen; J. Agustí; L. Cabrera

    1996-01-01

    The first detailed chronology for the middle to late Miocene continental record in Spain is presented, based on high-resolution magnetostratigraphic data of mammal-bearing sections which were studied in several basins (Calatayud-Daroca, Teruel, Vallès-Penedès, Duero and Júcar-Cabriel). Our results indicate that these sections compose an almost complete magnetostratigraphic succession from the lower Aragonian (MN4) to the middle Turolian (MN12). Seven successive

  1. Confirmation of a late Oligocene-early Miocene age of the Deseadan Salla Beds of Bolivia.

    USGS Publications Warehouse

    Naeser, C.W.; McKee, E.H.; Johnson, N.M.; Macfadden, B.J.

    1987-01-01

    Three new fission-track (zircon) and four new K-Ar (biotite) dates corroborate a late Oligocene-early Miocene age (22-28 Ma) for the Salla Beds of Bolivia. These ages contrast markedly with the previously accepted age of about 35 Ma for these strata and their contained faunas, and recasts of order and chronology of interchange between New World and Old World mammals. -Authors

  2. A molecular stable carbon isotope study of organic matter in immature Miocene Monterey sediments, Pismo basin

    SciTech Connect

    Schouten, S.; Rijpstra, I.C.; De Leeuw, J.W. [Netherlands Institute for Sea Research, Texel (Netherlands)] [and others] [Netherlands Institute for Sea Research, Texel (Netherlands); and others

    1997-05-01

    The 300 m section of the Miocene Monterey Formation outcropping at Shell Beach is composed of calcareous phosphatic (15.1 -14.5 Ma) and siliceous facies (14.5-11.0 Ma). An objective of this paper is to document lateral paleoenvironmental changes in the Miocene Monterey Formation by comparing the Shell Beach (SB) profile with the Naples Beach (NB) section in the Santa Barbara-Ventura basin. Eight samples (one sample representing, on average, a time period of ca. 2000 y) from this section were analyzed for variations of extractable biomarkers and their carbon isotopic signatures as indicators for paleoenvironmental change during the Miocene. Saturated hydrocarbons present include 28,30-dinorhopane, phytane, n-alkanes (C{sub 17}-C{sub 31}), lycopane, and 17{beta}, 21{beta}(H)-homohopane. The biomarkers released after desulfurization of the polar fractions predominantly consist of phytane, 2,6.10,14-tetramethyl-7-(3-methylpentyl)pentadecane, C{sub 17}-C{sub 31} n-alkanes. regular 5{alpha}- and 5{beta}-steranes, dinosteranes, and (22R)-17{beta},21{beta}(H)-pentakishomohopane. Steranes have similar carbon isotopic compositions (-25 to -27{per_thousand}) throughout the section and are isotopically similar at both sites, indicating laterally similar and vertically stable environmental conditions for algae living in the upper part of the photic zone. Free and S-bound n-alkanes at SB mainly originate from marine organisms and not from terrestrial sources as in the NB section. S-bound pentakishomohopane is ca. 1-49{per_thousand} depleted compared to the steranes and is thought to be derived from the deeper water dwelling cyanobacteria. These findings are consistent with stable carbon isotopic data obtained for these compounds from Middle Miocene Monterey sediments at Naples Beach and indicates similar environmental conditions in the depositional environments of the Santa Barbara-Ventura and the Pismo basin. 64 refs., 14 figs., 6 tabs.

  3. Miocene to recent eolian dust record from the Southwest Pacific Ocean at 40° S latitude

    Microsoft Academic Search

    Andrea M. Stancin; James D. Gleason; Steven A. Hovan; David K. Rea; Robert M. Owen; Theodore C. Moore Jr.; Chris M. Hall; Joel D. Blum

    2008-01-01

    A 14-meter long pelagic clay core recovered at Marlin Rise (40°00.531?S, 154°2.601?W; 4775 m water depth) in the Southwest Pacific Basin contains a record of eolian dust deposited since the early Miocene. Downcore analysis of detrital minerals reveals a dominantly eolian signature with relatively constant proportions of quartz, feldspar and illite and trace amounts of chlorite, kaolinite and smectite, consistent with

  4. Post-depositional alteration of titanomagnetite in a Miocene sandstone, south Texas (U.S.A.)

    Microsoft Academic Search

    Richard L. Reynolds

    1982-01-01

    Petrographic and geochemical studies have yielded information on the time-space relationships of the post-depositional alteration of detrital titanomagnetite (Ti-mt) in fine- to medium-grained sandstone from unoriented core samples (taken below the water table at depths of 30-45 m) of the Miocene Catahoula Sandstone, south Texas. Aqueous sulfide introduced from sour gas reservoirs along a growth fault into part of the

  5. Paleoenvironmental conditions in the Spanish Miocene-Pliocene boundary: isotopic analyses of Hipparion dental enamel.

    PubMed

    Domingo, Laura; Grimes, Stephen T; Domingo, M Soledad; Alberdi, M Teresa

    2009-04-01

    Expansion of C(4) grasses during Late Miocene and Early Pliocene constitutes one of the most remarkable biotic events of the Cenozoic era. The Teruel-Alfambra region (northeastern Spain) contains one of the most complete Miocene-Pliocene sequences of mammalian fossil sites in the world. In this study, stable isotope (delta (13)C and delta (18)O) analyses have been performed on the tooth enamel from the equid Hipparion from 19 localities spanning a time interval from approximately 10.9 to 2.7 Ma. This time range starts with the first appearance of this genus in Spain and ends at its extinction. An increase in delta (13)C at about 4.2 Ma has been observed, indicative of a shift toward a more open habitat. This shift may be related to a large scale vegetation change which occurred across the Miocene-Pliocene boundary when C(4) grasses expanded. This expansion might in turn be linked to global tectonic events such as the uplift of the Himalaya and/or the closure of the Panama Isthmus. However, other more regional factors may have ultimately enhanced the trend toward more open habitats in the Western Mediterranean Basin. The Messinian Salinity Crisis was a major environmental event that may have been responsible for the isotopic changes seen in the equid Hipparion from the Iberian Peninsula along with an increase in the aridity detected approximately 4.6 Ma ago in the Sahara. Even though the exact factor triggering the isotopic change observed in the Hipparion enamel remains mostly unknown, this study demonstrates that the global environmental changes detected across the Miocene-Pliocene boundary are also recorded in the realm of the Iberian Peninsula. PMID:19190888

  6. Diagenetic controls on porosity and permeability in Miocene carbonates, La Molata, Spain

    E-print Network

    Li, Zhaoqi

    2012-05-31

    -mesohaline mixing dolomitization………………………………………………………………….29 CHAPTER 3 Fig. 3-1. Location and general geological maps of Cabo de Gata………………...……..50 Fig. 3-2. Composite stratigraphy of Miocene carbonates of La Molata….…….....……..51 Fig. 3-3. Topographic...………….……..……..……..……..……..……..………..…...……..95 CHAPTER 4 Fig. 4-1. Location and generalized geological maps of Cabo de Gata…………..……..126 Fig. 4-2. Generalized stratigraphy of the La Molata study area…….……..……….…..127 Fig. 4-3. 2D cross section of La Molata…………..……..……..………………...……..128...

  7. Eustatic implications of late Miocene depositional sequences in the Melilla Basin, northeastern Morocco

    Microsoft Academic Search

    Kevin J. Cunningham; Richard H. Benson; Kruna Rakic-El Bied; Larry W. McKenna

    1997-01-01

    The age (?5.78 Ma or lower chron C3r) of the major drawdown of the Paleo-Mediterranean Sea during the Messinian Salinity Crisis has been established by combining results from stratigraphy, paleontology, magnetostratigraphy, and argon dating for a late Miocene sedimentary succession in the Melilla Basin, NE Morocco. This event is inferred from a marine-to-continental series of carbonate and siliciclastic rocks that

  8. Episodic early Miocene anatexis in the Ama Drime Massif, southern Tibet

    Microsoft Academic Search

    J. Yu; L. Zeng; J. Liu; L. Gao; K. Xie

    2010-01-01

    Cenozoic India-Asia collision resulted in profound crustal shortening and thickening that produced the Himalaya and Tibetan Plateau. However, extensional tectonics, represented by the E-W trending south Tibetan detachment system (STDS) and N-S trending normal faults, has been a salient feature of Himalayan geology since the Miocene. To the north of the Ama Drime Massif, the STDS is crosscut by N-S

  9. Middle Miocene ice sheet dynamics, deep-sea temperatures, and carbon cycling: A Southern Ocean perspective

    Microsoft Academic Search

    Amelia E. Shevenell; James P. Kennett; David W. Lea

    2008-01-01

    Relative contributions of ice volume and temperature change to the global ?1‰ ?18O increase at ?14 Ma are required for understanding feedbacks involved in this major Cenozoic climate transition. A 3-ma benthic foraminifer Mg\\/Ca record of Southern Ocean temperatures across the middle Miocene climate transition reveals ?2 ± 2°C cooling (14.2–13.8 Ma), indicating that ?70% of the increase relates to

  10. Functional anatomy of the limbs of erethizontidae (Rodentia, Caviomorpha): Indicators of locomotor behavior in Miocene porcupines.

    PubMed

    Candela, Adriana M; Picasso, Mariana B J

    2008-05-01

    Functional analysis of the limb bones of the erethizontid Steiromys duplicatus, one of the most abundant Miocene porcupines from Patagonia, provides evidence to infer their locomotor behavior. Remains of the giant Neosteiromys pattoni (Late Miocene of Northeast Argentina) are also analyzed. Osteological and myological features of extant porcupines were evaluated and used as a model to interpret the functional significance of Miocene species' limbs. Several features in erethizontids are compatible with the ability to climb: the low humeral tuberosities indicate a mobile gleno-humeral joint; the prominent and distally extended deltopectoral crest indicates a powerful pectoral muscle, which is particularly active when climbing; the humero-ulnar and humero-radial joints are indicative of pronation-supination movements; the well-developed lateral epicondylar ridge and the medially protruding entepicondyle are in agreement with an important development of the brachioradialis, supinator, flexor digitorum profundus, and pronator teres muscles, acting in climbing and grasping functions; the mechanical advantage of the biceps brachii would be emphasized because of its distal attachment on the bicipital tuberosity. As with extant porcupines, in Miocene species, the large femoral head would have permitted a broad range of abduction of the femur, and the medially protruding lesser trochanter would have emphasized the abduction and outward rotation of the femur by the action of the ilio-psoas complex. In S. duplicatus, the shape of the hip, knee, and cruro-astragalar, calcaneo-astragalar, and astragalo-navicular joints would have allowed lateral and rotational movements, although probably to a lesser degree than in extant porcupines. Foot features of S. duplicatus (e.g., great medial sesamoid bone, medial astragalar head, complete hallux) indicate that this species would have had grasping ability, but would not have achieved the high degree of specialization of Coendou. Steiromys duplicatus would have been a semiarboreal dweller, resembling Erethizon dorsatum. PMID:18157864

  11. Geometric and sedimentologic characteristic of Mid-Miocene lowstand reservoir sandstones, offshore northwest Java, Indonesia

    Microsoft Academic Search

    P. Lowry; Y. Kusumanegara; S. Warman

    1996-01-01

    Numerous reservoirs in the Upper Cibulakan Formation (Mid-Miocene) of the Offshore Northwest Java shelf occur in sharp-based sandbodies that range from less than 1 m up to 10 m in thickness. Well-log derived net-sand isopach and seismic amplitude maps of these sandbodies depict elongate features, that are 1-2 km wide and 5-8 km long. The orientation of the longest axis

  12. The demise of the Oligo-Miocene fluvial system of the Levant and its geodynamic significance

    NASA Astrophysics Data System (ADS)

    Vachtman, Dina; Mart, Yossi

    2015-04-01

    The Levant rift system is a linear assemblage of axial rifts and their mountainous flanks that comprises two structurally distinct sections. The southern segment is built of series of secondary axial grabens, which trend northwards and are separated from each other by poorly rifted threshold zones, which is the northern extension of the Red Sea continental break-up. The northern section comprises the SW-trending Karasu - Hatay rifts, from which the Ghab graben branches southwards, which is tectonically attributed to the westward migration of Anatolia. A system of large rivers transected the southern section of the Levant from central Arabia in the east to the Mediterranean Sea in the west during the Oligo-Miocene, leaving behind 5 km thick series of clastic deposits at sea, and sandstones and conglomerates of variable thickness on land. The demise of that fluvial system was gradual, stretching from the late Miocene to the early Pleistocene, where coastal rivers were truncated from their sources due to the growth of segmented rift. The geodynamic process that constrains the development of the rifts of the southern Levant and their elevated flanks is oblique rifting, where several small rifts start the evolution along a weakness zone concurrently, separated by wide and inactive threshold zones. Gradually the rifts grow along their long axes to interconnect, shrinking the threshold zone to their disappearence. Such geodynamic history best accounts for the observations of relicts of late Miocene fluvial deposits on mountaintops, large river beds dated to the late Miocene-early Pliocene, and large marine fan deposits of early Pliocene age, where rivers continued to flow in the threshold zones, but truncated by the emerging rifts.

  13. Antarctic ice-sheet response to atmospheric CO2 and insolation in the Middle Miocene

    Microsoft Academic Search

    P. M. Langebroek; A. Paul; M. Schulz

    2009-01-01

    Foraminiferal oxygen isotopes from deep-sea sediment cores suggest that a rapid expansion of the Antarctic ice sheet took place in the Middle Miocene around 13.9 million years ago. The origin for this transition is still not understood satisfactorily. One possible cause is a drop in the partial pressure of atmospheric carbon dioxide (pCO2) in combination with orbital forcing. A complication

  14. The Miocene Cyprideis species flock (Ostracoda; Crustacea) of western Amazonia (Solimões Formation)

    NASA Astrophysics Data System (ADS)

    Gross, Martin; Ramos, Maria Ines F.; Piller, Werner E.

    2015-04-01

    The Miocene mega-wetland of western Amazonia holds a diverse, largely endemic aquatic invertebrate fauna (e.g., molluscs, ostracods). Among ostracods, the genus Cyprideis experienced a remarkable radiation. Micropalaeontologic investigations of a 400-m-long sediment core (~62 km SW Benjamin Constant, Amazonia, Brazil) permitted a taxonomic revision of about two-thirds of hitherto described Cyprideis species. Ostracod index species enabled a biostratigraphic allocation of the well succession to the Cyprideis minipunctata to Cyprideis cyrtoma biozones (late middle to early late Miocene age). The current study underlines once more Cyprideis' remarkable capability to produce species flocks and western Amazonian Cyprideis comply with the criteria of a species flock: i) endemicity: up to now not a single species is recorded in adjacent areas; ii) monophyly: although hardly verifiable to date and probably Amazonian Cyprideis is not monophyletic s.str., several closely related, quite rapidly evolving species are proved; iii) speciosity: due to the present study, 30 formally described species exist; several further species, left in open nomenclature, are recorded in the literature, which strongly hints to a much higher, still unrecorded species richness; iv) ecological diversity: based on rare sedimentologic cross-references, ecological diversity within a highly structured wetland is possible; the current results demonstrate the sympatric occurrence of up to 12 Cyprideis species, which may indicate adaptations to different microhabitats; v) habitat dominance: regularly Cyprideis holds more than >90 % in western Amazonian ostracod assemblages during the early and middle Miocene. Explanations for this extreme habitat monopolisation are still arguable and touch the highly disputed question about the nature of western Amazonia's environments during the Miocene. It seems, however, evident that a strictly actualistic approach to endemic Neogene Amazonian biota is highly problematic. This study was funded by Austrian Science Fund (FWF project P21748-N21).

  15. Origin and structure of the fossil resin from an Indonesian Miocene coal

    Microsoft Academic Search

    W. Brackman; K. Spaargaren; J. P. C. M. van Dongen; P. A. Couperus; F. Bakker

    1984-01-01

    The structure of a fossil resin from Miocene coal outcrops of the Bukit Asam region (Sumatra) has been studied. The fossil material has been formed from sesqui- and tri-terpenes from trees of the Dipterocarp family. The original terpenes have lost virtually all oxygen-containing functions and the resulting mono- and di-olefins have polymerized to a mainly non-crosslinked resin whose components have

  16. Soft-sediment deformation structures in seismically affected deep-sea Miocene turbidites (Cilento Basin, southern Italy)

    NASA Astrophysics Data System (ADS)

    Valente, Alessio; ?l?czka, Andrzej; Cavuoto, Giuseppe

    2014-07-01

    Soft-sediment deformation structures (SSDS) are widespread in the upper part of the S. Mauro Formation (Cilento Group, Middle-Late Miocene). The succession is represented mainly by thick and very thick, massive, coarse-grained sandstones, deposited by rapid sedimentation of high-density turbidity currents. The most common SSDS are short pillars, dishes, sedimentary sills and convolutions. They occur mostly in the upper parts of sandstone beds. Vertical tubes of 4-5 cm in diameter and up to 50 cm long constitute the most striking structures. They begin in the middle part of sandstone beds, which are basically massive or contain faint dish structures. These tubes can bifurcate upwards and/ or pass into bedding-parallel veins or dikes. The vertical tubes sometimes form sand volcanoes on the then sedimentary surface. The SSDS are interpreted as the result of earthquake-triggered liquefaction and/or fluidisation of the turbidites that were affected by the seismic shocks. This implies that the deformed layers should be considered as seismites.

  17. Multivariate statistical analyses of palynodebris from the Middle Miocene of the Niger Delta and their environmental significance

    SciTech Connect

    Oboh, F.E. (Univ. of Missouri, Rolla (United States))

    1992-12-01

    Fourteen types of palynodebris have been identified in Middle Miocene reservoir sediments from the Niger Delta. They include palynomorphs, cuticle, parenchyma, resins, black debris, woody fragments and degraded components. The palynodebris types were interpreted by Principal Components Analysis and Average Linkage Cluster Analysis. Four assemblages of samples emerged and they have been grouped into two palynofacies associations, A/C and B/D, because of their correlation with mudstone and muddy heterolithic lithofacies and sandstone lithofacies, respectively. The significant palynodebris components are black debris, parenchyma, resins and amorphous organic matter. The size, shape and texture of all the components were integrated with sedimentological features, palynomorph and foraminiferal assemblages to recognize seven, possibly eight, deltaic sub-environments of deposition in the reservoir. Mudstones and muddy heteroliths from low energy depositional environments are characterized by small-sized, lath-shaped woody debris, and high concentration of buoyant components such as palynomorphs, cuticles and degraded bundles. The sandstones contain larger and more equidimensional woody fragments. These sediments are also richer in black debris which are believed to be a function of exposure to oxidizing conditions for a longer period of time. Parenchyma and resins, though rare, are characteristic of distributary channel-fill sandstones. 59 refs., 7 figs., 3 tabs.

  18. Middle Miocene environmental and climatic evolution at the Wilkes Land margin, East Antarctica

    NASA Astrophysics Data System (ADS)

    Sangiorgi, F.; Passchier, S.; Salzmann, U.; Schouten, S.; Pross, J.; Bijl, P.; Tauxe, L.; Bendle, J. A.; Escutia, C.; Brinkhuis, H.

    2012-12-01

    Integrated Ocean Drilling Program (IODP) Expedition 318 successfully drilled a Middle Miocene (~ 17 - 12.5 Ma) record from the Wilkes Land Margin at Site U1356A (63°18.6138'S, 135°59.9376'E), located at the transition between the continental rise and the abyssal plain at 4003 mbsl. We present a multiproxy palynological (dinoflagellate cyst, pollen and spores), sedimentological and organic geochemical (TEX86, MBT/CBT) study, which unravels the environmental and climate variability across the Miocene Climatic Optimum (MCO, ~17-15 Ma) and the Mid Miocene Climate Transition (MMCT). Several independent lines of evidence indeed suggest a relatively warm climate during the MCO. Dinocyst and pollen assemblage diversity at the MCO is unprecedented for a Neogene Antarctic record and indicates a temperate, sea ice-free marine environment, with woody sub-antarctic vegetation with elements of forest/shrub tundra and peat lands along the coast. These results are further confirmed by relatively warm TEX86-derived Sea Surface Temperatures and mild MBT-derived continental temperatures, and by the absence of glacially derived deposits and very few ice-rafted clasts. A generally colder but highly dynamic environment is suggested for the interval 15-12.5 Ma.

  19. Equatorial Precession Drove Mid-Latitude Changes in ENSO-Scale Variation in the Earliest Miocene

    NASA Astrophysics Data System (ADS)

    Fox, B.; D'Andrea, W. J.; Lee, D. E.; Wilson, G. S.

    2014-12-01

    Foulden Maar is an annually laminated lacustrine diatomite deposit from the South Island of New Zealand. The deposit was laid down over ~100 kyr of the latest Oligocene and earliest Miocene, during the peak and deglaciation phase of the Mi-1 Antarctic glaciation event. At this time, New Zealand was located at approximately the same latitude as today (~45°S). Evidence from organic geochemical proxies (?D, ?13C) and physical properties (density, colour) indicates the presence of an 11-kyr cycle at the site. Although it is known that 11-kyr insolation (half-precession) cycles occur between the Tropics, this cycle is rarely seen in sedimentary archives deposited outside the immediate vicinity of the Equator. Records from Foulden Maar correlate well with the amplitude and phase of the modelled equatorial half-precession cycle for the earliest Miocene. High-resolution (50 µm) colour intensity measurements and lamina thickness measurements both indicate the presence of significant ENSO-like (2-8 year) variation in the Foulden Maar sediments. Early results from targeted lamina thickness measurements suggest that ENSO-band variation is modulated by the 11-kyr cycle, with power in the ENSO band increasing during periods of increased insolation at the Equator. This implies that equatorial half-precession had a significant effect on ENSO-like variation in the early Miocene, and that this effect was felt as far afield as the mid-latitudes of the Southern Hemisphere.

  20. Fossil wood from the Miocene and Oligocene epoch: chemistry and morphology.

    PubMed

    Bardet, Michel; Pournou, Anastasia

    2015-01-01

    Fossil wood is the naturally preserved remain of the secondary xylem of plants that lived before the Holocene epoch. Typically, fossil wood is preserved as coalified or petrified and rarely as mummified tissue. The process of fossilization is very complex and it is still unknown why in the same fossil record, wood can be found in different fossilisation forms. In 2007, a fossil forest was found in the Bükkábrány open-pit coal mine in Hungary. The non-petrified forest is estimated to be 7 million years old (Miocene epoch) and its trees were found standing in an upright position. This fossil assemblage is exceptionally rare because wood has been preserved as soft waterlogged tissue. This study aimed to investigate this remarkable way of fossil wood preservation, by examining its chemistry with (13)C CPMAS NMR and its morphology with light and electron microscopy. For comparison reasons, a petrified wood trunk from the Oligocene epoch (30 Myr) found in 2001 at Porrentruy region in Switzerland and two fresh wood samples of the modern equivalents of the Miocene sample were also examined. The results obtained showed that the outstanding preservation state of the Miocene fossil is not owed to petrification or coalification. Mummification is a potential mechanism that could explain Bükkábrány trunks' condition, however this fossilisation process is not well studied and therefore this hypothesis needs to be further investigated. PMID:25294390

  1. Dental microwear profilometry of African non-cercopithecoid catarrhines of the Early Miocene.

    PubMed

    Shearer, Brian M; Ungar, Peter S; McNulty, Kieran P; Harcourt-Smith, William E H; Dunsworth, Holly M; Teaford, Mark F

    2015-01-01

    The Early Miocene of Kenya has yielded the remains of many important stem catarrhine species that provide a glimpse of the East African primate radiation at a time of major faunal turnover. These taxa have been subject to innumerable studies, yet there is still no consensus on their dietary niches. Here we report results of an analysis of dental microwear textures of non-cercopithecoid catarrhines from the Early Miocene of Kenya. Scanning confocal profilometry of all available molar specimens with undamaged occlusal surfaces revealed 82 individuals with unobscured antemortem microwear, representing Dendropithecus, Micropithecus, Limnopithecus, Proconsul, and Rangwapithecus. Scale-sensitive fractal analysis was used to generate microwear texture attributes for each individual, and the fossil taxa were compared with each other using conservative non-parametric statistical tests. This study revealed no discernible variation in microwear texture among the fossil taxa, which is consistent with results from a previous feature-based microwear study using smaller samples. Our results suggest that, despite their morphological differences, these taxa likely often consumed foods with similar abrasive and fracture properties. However, statistical analyses of microwear texture data indicate differences between the Miocene fossil sample and several extant anthropoid primate genera. This suggests that the African non-cercopithecoid catarrhines included in our study, despite variations in tooth form, had generalist diets that were not yet specialized to the degree of many modern taxa. PMID:25282274

  2. Miocene structural features of north and south Padre Island and OCS areas, offshore south Texas

    SciTech Connect

    Al-Ghamdi, A.M.; Watkins, J.S. (Texas A M Univ., College Station, TX (United States))

    1996-01-01

    Integration of 2-D seismic reflection data, paleontological reports, velocity analysis, and well logs has provided a new structural model for North and South Padre Island OCS areas. The Clemente-Tomas fault system (Late Oligocene-Early Miocene) is located above overpressured shale ridges. Sediment loading initiated the faulting over the compacted shale. The Corsair fault system (Early-Middle Miocene) is located seaward of Clemente-Tomas and was formed due to a huge sediment influx that forced the salt to withdraw basinward. The Wanda fault system formed during the Late Miocene because of the further salt withdrawal. Study area is dominated by shale ridges and the salt are only formed beneath the present shelf edge as salt diapirs. Overpressured shale was mapped throughout the study area. Well logs show overpressured shale between 8,800 to 12,000 feet. Berg and Avery suggested that growth faults can seal the faults sheared zones which may cause a structural hydrocarbon trap. We examined most of the responses of the dip logs in the study area and we found that the seal general trend is the drag (non seal) type.

  3. Miocene structural features of north and south Padre Island and OCS areas, offshore south Texas

    SciTech Connect

    Al-Ghamdi, A.M.; Watkins, J.S. [Texas A& M Univ., College Station, TX (United States)

    1996-12-31

    Integration of 2-D seismic reflection data, paleontological reports, velocity analysis, and well logs has provided a new structural model for North and South Padre Island OCS areas. The Clemente-Tomas fault system (Late Oligocene-Early Miocene) is located above overpressured shale ridges. Sediment loading initiated the faulting over the compacted shale. The Corsair fault system (Early-Middle Miocene) is located seaward of Clemente-Tomas and was formed due to a huge sediment influx that forced the salt to withdraw basinward. The Wanda fault system formed during the Late Miocene because of the further salt withdrawal. Study area is dominated by shale ridges and the salt are only formed beneath the present shelf edge as salt diapirs. Overpressured shale was mapped throughout the study area. Well logs show overpressured shale between 8,800 to 12,000 feet. Berg and Avery suggested that growth faults can seal the faults sheared zones which may cause a structural hydrocarbon trap. We examined most of the responses of the dip logs in the study area and we found that the seal general trend is the drag (non seal) type.

  4. Upper Miocene Stevens sands in the Maricopa depocenter southern San Joaquin Valley, California

    SciTech Connect

    Quinn, M.J. (Chevron USA, Inc., Houston, TX (United States))

    1991-02-01

    During the late Miocene, the Maricopa depocenter was a northwest-southeast-trending trough located in the southeastern corner of the San Joaquin Valley. Uplifting granitic source terranes in the Salinian block to the southwest, the Sierra Nevada to the northeast, and the Tehachapi Mountains to the southeast shed coarse-grained quartz-rich sands into the subsiding basin in the form of deep marine turbidites. These upper Miocene turbidites are collectively referred to as the Stevens sands. Based upon studies from several oil fields within the depocenter, a generalized model has been developed for the ramp, channel, and fan deposits seen within the Stevens system. This model, and the field studies are used to examine the size, morphology, sand distribution patterns, and seismic response of these sand-rich turbidite deposits. Within the Stevens system, the majority of the hydrocarbons are found within the middle to outer parts of the turbidites fans, with post depositional compaction, uplift, and folding providing three primary types of trapping mechanism: closure due to shale compaction over sand thicks, emplacement of sands across an anticlinal axis, and updip porosity pinch-outs. Finally, the chronostratigraphy of the basin developed from the field studies is used to examine upper Miocene strike-slip movement along the San Andreas fault, uplift of the Sierra Nevada, strike-slip and normal movement along the White Wolf fault, and how these various tectonic events relate to the Stevens deposition.

  5. Terpenoid Compositions and Botanical Origins of Late Cretaceous and Miocene Amber from China

    PubMed Central

    Shi, Gongle; Dutta, Suryendu; Paul, Swagata; Wang, Bo; Jacques, Frédéric M. B.

    2014-01-01

    The terpenoid compositions of the Late Cretaceous Xixia amber from Central China and the middle Miocene Zhangpu amber from Southeast China were analyzed by gas chromatography-mass spectrometry (GC-MS) to elucidate their botanical origins. The Xixia amber is characterized by sesquiterpenoids, abietane and phyllocladane type diterpenoids, but lacks phenolic abietanes and labdane derivatives. The molecular compositions indicate that the Xixia amber is most likely contributed by the conifer family Araucariaceae, which is today distributed primarily in the Southern Hemisphere, but widely occurred in the Northern Hemisphere during the Mesozoic according to paleobotanical evidence. The middle Miocene Zhangpu amber is characterized by amyrin and amyrone-based triterpenoids and cadalene-based sesquiterpenoids. It is considered derived from the tropical angiosperm family Dipterocarpaceae based on these compounds and the co-occurring fossil winged fruits of the family in Zhangpu. This provides new evidence for the occurrence of a dipterocarp forest in the middle Miocene of Southeast China. It is the first detailed biomarker study for amber from East Asia. PMID:25354364

  6. Juvenile hominoid cranium from the late Miocene of southern China and hominoid diversity in Asia

    PubMed Central

    Kelley, Jay; Gao, Feng

    2012-01-01

    The fossil ape Lufengpithecus is known from a number of late Miocene sites in Yunnan Province in southern China. Along with other fossil apes from South and Southeast Asia, it is widely considered to be a relative of the extant orangutan, Pongo pygmaeus. It is best represented at the type site of Shihuiba (Lufeng) by several partial to nearly complete but badly crushed adult crania. There is, however, an additional, minimally distorted cranium of a young juvenile from a nearly contemporaneous site in the Yuanmou Basin, which affords the opportunity to better assess the relationships between Lufengpithecus and Pongo. Comparison with similarly aged juvenile skulls of extant great apes reveals no features suggesting clear affinities to orangutans, and instead reveals a morphological pattern largely consistent with a stem member of the hominid (great ape and human) clade. The existence at this time of other hominids in South Asia (Sivapithecus) and Southeast Asia (Khoratpithecus) with clear craniofacial affinities to Pongo suggests both more diversity among Asian Late Miocene apes and more complex patterns of dispersal than previously supposed. Major differences in the associated mammal faunas from the southern China sites and those from South and Southeast Asia are consistent with these findings and suggest more than one dispersal route of apes into East Asia earlier in the Miocene. PMID:22511723

  7. Late Miocene remagnetization within the internal sector of the Northern Apennines, Italy

    USGS Publications Warehouse

    Aiello, I.W.; Hagstrum, J.T.; Principi, G.

    2004-01-01

    Paleomagnetic and geologic evidence indicates that Upper Jurassic radiolarian cherts of both the Tuscan Cherts Formation (continental margin, Tuscan Units) and the Monte Alpe Cherts Formation (oceanic crust, Ligurian Units) were remagnetized during Miocene orogenesis of the Northern Apennines of Italy. Characteristic overprint magnetizations with reversed polarities have been found over a large area within the internal sector of the Northern Apennines, including eastern Liguria, Elba Island and the Thyrrenian margin, and west of the Middle Tuscan Ridge. The reversed-polarity overprint (average direction: D=177??, I=-52??, ??95=15??) was most likely acquired during Late Miocene uplift and denudation of the orogenic chain, and thermochemical remagnetization was a probable consequence of increased circulation of orogenic fluids. Similarly, mostly reversed-polarity directions of magnetization have been found by other workers in overlying post-orogenic Messinian sediments (D=177??, I=-57??, ??95=3??), which show little counterclockwise (CCW) vertical-axis rotation with respect to stable Europe (-8??5??). The Monte Alpe Cherts sampled at sites in the external sector of the Northern Apennines, close to major tectonic features, have normal- polarity overprint directions with in situ W-SW declinations. Since the overlying post-orogenic Messinian sediments have not been substantially rotated about vertical axes, the evidence points to an earlier,pre-Late Miocene remagnetization in the external parts of the orogenic chain. ?? 2004 Elsevier B.V. All rights reserved.

  8. Middle Miocene environmental and climatic evolution at the Wilkes Land margin, East Antarctica

    NASA Astrophysics Data System (ADS)

    Sangiorgi, Francesca; Bijl, Peter; Passchier, Sandra; Salzmann, Ulrich; Schouten, Stefan; Pross, Jörg; Escutia, Carlota; Brinkhuis, Henk

    2015-04-01

    Integrated Ocean Drilling Program (IODP) Expedition 318 successfully drilled a Middle Miocene (~ 17 - 12.5 Ma) record from the Wilkes Land Margin at Site U1356A (63°18.6138'S, 135°59.9376'E), located at the transition between the continental rise and the abyssal plain at 4003 mbsl. We present a multiproxy palynological (dinoflagellate cyst, pollen and spores), sedimentological and organic geochemical (TEX86, MBT/CBT) study, which unravels the environmental and climate variability across the Miocene Climatic Optimum (MCO, ~17-15 Ma) and the Mid Miocene Climate Transition (MMCT). Several independent lines of evidence suggest a relatively warm climate during the MCO. Dinocyst and pollen assemblage diversity at the MCO is unprecedented for a Neogene Antarctic record and indicates a temperate, sea ice-free marine environment, with woody sub-antarctic vegetation with elements of forest/shrub tundra and peat lands along the coast. These results are further confirmed by relatively warm TEX86-derived Sea Surface Temperatures and mild MBT-derived continental temperatures, and by the absence of glacially derived deposits and very few ice-rafted clasts. A generally colder but highly dynamic environment is suggested for the interval 15-12.5 Ma.

  9. Seastacks buried beneath newly reported Lower Miocene sandstone, northern Santa Barbara County, California

    SciTech Connect

    Fritsche, A.E.; Hanna, F.M.

    1985-04-01

    Three large, isolated exposures of a light-gray, coarse-grained, thick-bedded sandstone unit occur in the northern San Rafael Mountains of Santa Barbara County, California. These rocks are moderately fossiliferous and contain Vertipecten bowersi, Amussiopecten vanvlecki, Aequipecten andersoni, Otrea howelli, shark teeth, whale bones, and regular echinoid spines. The fossils indicate that the sandstone unit, although previously reported as upper(.) Miocene, correlates best with the lower Miocene Vaqueros Formation. This unit was deposited in angular unconformity on a Cretaceous, greenish-gray turbidite sequence of interbedded sandstone and shale, and onlaps the unconformity erosion surface from west to east, the unit being thicker in the west and older at its base. The underlying Cretaceous sandstone beds are well indurated, and during the eastward transgression of the early Miocene sea, they resisted wave erosion and stood as seastacks offshore of the advancing coastline, thus creating a very irregular topographic surface upon which the Vaqueros Formation was deposited. Some seastacks were as much as 4 m tall, as indicated by inliers of Cretaceous rock surrounded by 4-m thick sections of the Vaqueros Formation.

  10. Re-organization of Pacific intermediate and deep water circulation during middle Miocene stepwise onset of

    NASA Astrophysics Data System (ADS)

    Holbourn, A.; Kuhnt, W.; Regenberg, M.; Haley, B.; Frank, M.; Mix, A.; Andersen, N.

    2008-12-01

    We use benthic and planktonic foraminiferal ?13C and ?18O, planktonic Mg/Ca together with Nd isotopes and deep-water ventilation proxies (benthic foraminiferal accumulation rates, proportion of coarse fraction and XRF Fe) in ODP cores from the NW and SE Pacific to track circulation changes across the Pacific and to elucidate the role of the tropics during middle Miocene global climate change (16.5-12.5 Ma). Our high resolution (3-4 kyr) planktonic ?18O record from South China Sea Site 1146 exhibits high amplitude variability with significant power in the obliquity and precessional bands, suggesting that a monsoonal regime was established in SE Asia by the middle Miocene. Following episodes of ice expansion at 14.6, 14.2 and 13.9 Ma, planktonic ?18O values strikingly decreased and SST estimates increased, suggesting intensification of summer monsoon coupled with northwards shifts of the ITCZ (close to present day position). Nd isotopes and ventilation proxies in SE Pacific Sites 1236 and 1237 also reveal that Antarctic glaciation events were associated with deepening of the Calcite Compensation Depth and major re- organization of intermediate and deep water circulation in the Pacific. Thus, our results indicate a tight coupling of tropical and southern hemisphere climate as well as heightened sensitivity to obliquity and precessional forcing during the stepwise onset of icehouse conditions in the middle Miocene.

  11. Terpenoid compositions and botanical origins of Late Cretaceous and Miocene amber from China.

    PubMed

    Shi, Gongle; Dutta, Suryendu; Paul, Swagata; Wang, Bo; Jacques, Frédéric M B

    2014-01-01

    The terpenoid compositions of the Late Cretaceous Xixia amber from Central China and the middle Miocene Zhangpu amber from Southeast China were analyzed by gas chromatography-mass spectrometry (GC-MS) to elucidate their botanical origins. The Xixia amber is characterized by sesquiterpenoids, abietane and phyllocladane type diterpenoids, but lacks phenolic abietanes and labdane derivatives. The molecular compositions indicate that the Xixia amber is most likely contributed by the conifer family Araucariaceae, which is today distributed primarily in the Southern Hemisphere, but widely occurred in the Northern Hemisphere during the Mesozoic according to paleobotanical evidence. The middle Miocene Zhangpu amber is characterized by amyrin and amyrone-based triterpenoids and cadalene-based sesquiterpenoids. It is considered derived from the tropical angiosperm family Dipterocarpaceae based on these compounds and the co-occurring fossil winged fruits of the family in Zhangpu. This provides new evidence for the occurrence of a dipterocarp forest in the middle Miocene of Southeast China. It is the first detailed biomarker study for amber from East Asia. PMID:25354364

  12. First Occurrence of Platycladus from the Upper Miocene of Southwest China and Its Phytogeographic Implications

    PubMed Central

    Li, Qi-Jia; Zhao, Zhen-Rui; Sun, Bai-Nian

    2014-01-01

    Platycladus Spach is native to Central China, but its natural occurrences are very difficult to establish. According to molecular phylogenetic data, this genus might have originated since the Oligocene, but no fossil record has been reported. Here, we describe eight foliage branches from the upper Miocene in western Yunnan, Southwest China as a new species, P. yunnanensis sp. nov., which is characterized by foliage branches spread in flattened sprays, and leaves decussate, imbricate, scale-like and dimorphic. The leaves are amphistomatic, and the stomata are elliptical or oblong, haplocheilic, and monocyclic type. Based on a detailed comparison with the extant genera of Cupressaceae sensu lato, our fossils are classified into the genus Platycladus. The occurrence of P. yunnanensis sp. nov. indicates that this genus had a more southernly natural distribution in the late Miocene than at present. Molecular phylogeny and fossil records support a pre-Oligocene common ancestor for the genera Platycladus, Microbiota and Calocedrus. The separation of the three taxa was most likely caused by the arid belt across Central China during the Oligocene. In addition, the cooling down of the global temperature and the strengthening of Asian monsoon since the Miocene will further promote the migration of these genera. PMID:25517767

  13. The sensitivity of ECHAM4/ML to a double CO 2 scenario for the Late Miocene and the comparison to terrestrial proxy data

    NASA Astrophysics Data System (ADS)

    Steppuhn, Anke; Micheels, Arne; Bruch, Angela A.; Uhl, Dieter; Utescher, Torsten; Mosbrugger, Volker

    2007-06-01

    For the Tortonian, Steppuhn et al. [Steppuhn, A., Micheels, A., Geiger, G., Mosbrugger, V., 2006. Reconstructing the Late Miocene climate and oceanic heat flux using the AGCM ECHAM4 coupled to a mixed-layer ocean model with adjusted flux correction. Palaeogeography, Palaeoclimatology, Palaeoecology, 238, 399-423] perform a model simulation which considers a generally lower palaeorography, a weaker ocean heat transport and an atmospheric CO 2 concentration of 353 ppm. The Tortonian simulation of Steppuhn et al. [Steppuhn, A., Micheels, A., Geiger, G., Mosbrugger, V., 2006. Reconstructing the Late Miocene climate and oceanic heat flux using the AGCM ECHAM4 coupled to a mixed-layer ocean model with adjusted flux correction. Palaeogeography, Palaeoclimatology, Palaeoecology, 238, 399-423] demonstrates some realistic trends: the high latitudes are warmer than today and the meridional temperature gradient is reduced. However, the Tortonian run also indicates some insufficiencies such as too cool mid-latitudes which can be due to an underestimated pCO 2 in the atmosphere. As a sensitivity study, we perform a further model experiment for which we additionally increase the atmospheric carbon dioxide (700 ppm). According to this CO 2 sensitivity experiment, we find a global warming and a globally more intense water cycle as compared to the previous Tortonian run. Particularly the high latitudes are warmer in the Tortonian CO 2 sensitivity run which leads to a lower amount of Arctic sea ice and a reduced equator-to-pole temperature difference. Our Tortonian CO 2 sensitivity study basically agrees with results from recent climate model experiments which consider an increase of CO 2 during the next century (e.g. [Cubasch, U., Meehl, G.A., Boer, G.J., Stouffer, R.J., Dix, M., Noda, A., Senior, C.A., Raper, S., Yap, K.S., 2001. Projections of Future Climate Change. In: Houghton, J.T., Y. Ding, D.J. Griggs, M. Noguer, P.J. van der Linden, X. Dai, K. Maskell, C.A. Johnson (eds.), Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, 525-582]) suggesting that the climatic response on a higher atmospheric CO 2 concentration is almost independent from the different settings of boundary conditions (Tortonian versus today). To validate the Tortonian model simulations, we perform a quantitative comparison with terrestrial proxy data. This comparison demonstrates that the Tortonian CO 2 sensitivity experiment tends to be more realistic than the previous Tortonian simulation by Steppuhn et al. [Steppuhn, A., Micheels, A., Geiger, G., Mosbrugger, V., 2006. Reconstructing the Late Miocene climate and oceanic heat flux using the AGCM ECHAM4 coupled to a mixed-layer ocean model with adjusted flux correction. Palaeogeography, Palaeoclimatology, Palaeoecology, 238, 399-423]. However, a high carbon dioxide concentration of 700 ppm is questionable for the Late Miocene, and it cannot explain shortcomings of our Tortonian run with 'normal' CO 2. In order to fully understand the Late Miocene climate, further model experiments should also consider the palaeovegetation.

  14. Palinspastic reconstruction of southeastern California and southwestern Arizona for the middle Miocene

    NASA Technical Reports Server (NTRS)

    Richard, Stephen M.

    1992-01-01

    A paleogeographic reconstruction of southeastern California and southwestern Arizona at 10 Ma was made based on available geologic and geophysical data. Clockwise rotation of 39 deg was reconstructed in the eastern Transverse Ranges, consistent with paleomagnetic data from late Miocene volcanic rocks, and with slip estimates for left-lateral faults within the eastern Transverse Ranges and NW-trending right lateral faults in the Mojave Desert. This domain of rotated rocks is bounded by the Pinto Mountain fault on the north. In the absence of evidence for rotation of the San Bernardino Mountains or for significant right slip faults within the San Bernardino Mountains, the model requires that the late Miocene Pinto Mountain fault become a thrust fault gaining displacement to the west. The Squaw Peak thrust system of Meisling and Weldon may be a western continuation of this fault system. The Sheep Hole fault bounds the rotating domain on the east. East of this fault an array of NW-trending right slip faults and south-trending extensional transfer zones has produced a basin and range physiography while accumulating up to 14 km of right slip. This maximum is significantly less than the 37.5 km of right slip required in this region by a recent reconstruction of the central Mojave Desert. Geologic relations along the southern boundary of the rotating domain are poorly known, but this boundary is interpreted to involve a series of curved strike slip faults and non-coaxial extension, bounded on the southeast by the Mammoth Wash and related faults in the eastern Chocolate Mountains. Available constraints on timing suggest that Quaternary movement on the Pinto Mountain and nearby faults is unrelated to the rotation of the eastern Transverse Ranges, and was preceded by a hiatus during part of Pliocene time which followed the deformation producing the rotation. The reconstructed Clemens Well fault in the Orocopia Mountains, proposed as a major early Miocene strand of the San Andreas fault, projects eastward towards Arizona, where early Miocene rocks and structures are continuous across its trace. The model predicts a 14 deg clockwise rotation and 55 km extension along the present trace of the San Andreas fault during late Miocene and early Pliocene time. Palinspastic reconstructions of the San Andreas system based on this proposed reconstruction may be significantly modified from current models.

  15. The Late Miocene paleogeography of the Amazon Basin and the evolution of the Amazon River system

    NASA Astrophysics Data System (ADS)

    Latrubesse, Edgardo M.; Cozzuol, Mario; da Silva-Caminha, Silane A. F.; Rigsby, Catherine A.; Absy, Maria Lucia; Jaramillo, Carlos

    2010-05-01

    On the basis of paleontological content (vertebrates and palynology) and facies analysis from river banks, road cuts, and three wells, we have assigned the uppermost levels of the Solimões Formation in western Amazonia, Brazil, to the Late Miocene. The vertebrate fossil record from outcropping sediments is assigned to the Huayquerian-Mesopotamian mammalian biozones, spanning 9-6.5 Ma. Additionally, we present results that demonstrate that deposits in Peruvian Amazonia attributed to Miocene tidal environments are actually fluvial sediments that have been misinterpreted (both environmentally and chronologically) by several authors. The entire Late Miocene sequence was deposited in a continental environment within a subsiding basin. The facies analysis, fossil fauna content, and palynological record indicate that the environment of deposition was dominated by avulsive rivers associated with megafan systems, and avulsive rivers in flood basins (swamps, lakes, internal deltas, and splays). Soils developed on the flatter, drier areas, which were dominated by grasslands and gallery forest in a tropical to subtropical climate. These Late Miocene sediments were deposited from westward of the Purus arch up to the border of Brazil with Peru (Divisor Ranges) and Bolivia (Pando block). Eastward of the Iquitos structural high, however, more detailed studies, including vertebrate paleontology, need to be performed to calibrate with more precision the ages of the uppermost levels of the Solimões Formation. The evolution of the basin during the late Miocene is mainly related to the tectonic behavior of the Central Andes (˜ 3°-15°S). At approximately 5 Ma, a segment of low angle of subduction was well developed in the Nazca Plate, and the deformation in the Subandean foreland produced the inland reactivation of the Divisor/Contamana Ranges and tectonic arrangements in the Eastern Andes. During the Pliocene southwestern Brazilian Amazonia ceased to be an effective sedimentary basin, and became instead an erosional area that contributed sediments to the Amazon fluvial system. At that time, the lowland fluvial systems of southwestern Amazonia (the Purus, Jurua and Javarí basins) become isolated from the Andes by the newly formed north-flowing Ucayali system and south-east flowing Madre de Dios System. It was during the early Pliocene that the Amazon fluvial system integrated regionally and acquired its present appearance, and also when it started to drain water and sediments on a large scale to the Atlantic Ocean.

  16. Palinspastic reconstruction of southeastern California and southwestern Arizona for the middle Miocene

    NASA Astrophysics Data System (ADS)

    Richard, Stephen M.

    1992-12-01

    A paleogeographic reconstruction of southeastern California and southwestern Arizona at 10 Ma was made based on available geologic and geophysical data. Clockwise rotation of 39 deg was reconstructed in the eastern Transverse Ranges, consistent with paleomagnetic data from late Miocene volcanic rocks, and with slip estimates for left-lateral faults within the eastern Transverse Ranges and NW-trending right lateral faults in the Mojave Desert. This domain of rotated rocks is bounded by the Pinto Mountain fault on the north. In the absence of evidence for rotation of the San Bernardino Mountains or for significant right slip faults within the San Bernardino Mountains, the model requires that the late Miocene Pinto Mountain fault become a thrust fault gaining displacement to the west. The Squaw Peak thrust system of Meisling and Weldon may be a western continuation of this fault system. The Sheep Hole fault bounds the rotating domain on the east. East of this fault an array of NW-trending right slip faults and south-trending extensional transfer zones has produced a basin and range physiography while accumulating up to 14 km of right slip. This maximum is significantly less than the 37.5 km of right slip required in this region by a recent reconstruction of the central Mojave Desert. Geologic relations along the southern boundary of the rotating domain are poorly known, but this boundary is interpreted to involve a series of curved strike slip faults and non-coaxial extension, bounded on the southeast by the Mammoth Wash and related faults in the eastern Chocolate Mountains. Available constraints on timing suggest that Quaternary movement on the Pinto Mountain and nearby faults is unrelated to the rotation of the eastern Transverse Ranges, and was preceded by a hiatus during part of Pliocene time which followed the deformation producing the rotation. The reconstructed Clemens Well fault in the Orocopia Mountains, proposed as a major early Miocene strand of the San Andreas fault, projects eastward towards Arizona, where early Miocene rocks and structures are continuous across its trace. The model predicts a 14 deg clockwise rotation and 55 km extension along the present trace of the San Andreas fault during late Miocene and early Pliocene time. Palinspastic reconstructions of the San Andreas system based on this proposed reconstruction may be significantly modified from current models.

  17. The strontium isotope seawater curve during the early Middle Miocene and its relation to paleoceanographic events

    SciTech Connect

    Hodell, D.A. (Univ. of Florida, Gainesville, FL (United States). Dept. of Geology); Woodruff, F. (Univ. of Southern California, Los Angeles, CA (United States). Dept. Geological Sciences)

    1992-01-01

    Breaks in slope of the strontium isotope seawater curve signal fundamental changes in either rates of continental weathering, seafloor spreading (i.e., tectonic reorganizations), or submarine dissolution of marine carbonates. The authors conducted a detailed study of the change in slope of the strontium isotopic seawater curve that occurred during the early middle Miocene in three Pacific DSDP sites (289, 574, and 588). The change in slope from the rapid rise in Sr-87/Sr-86 of the early Miocene (60 ppm/Ma) to the less rapid increase of the mid- and late Miocene (22 ppm/Ma) occurred between two periods of maximum [delta]C-13 values dated between 15.5 and 15.2 Ma. This internal was followed by relatively constant Sr-87/Sr-86 values (averaging 0.70878) between 15.2 and 14.2 Ma. Sr-87/Sr-86 ratios began to increase again after 14.2 Ma, but at a reduced rate compared to the early Miocene. The break in slope in Sr-87/Sr-86 preceded the mid-Miocene increase in [delta]O-18 that represents ice growth on Antarctica, which began at 14.9 Ma and increased rapidly after 14.2 Ma. In 2 out of 3 of the sites, the break in Sr-slope between 15.5 and 15.2 Ma is accompanied by a small, but significant, decrease in Sr-87/Sr-86 values. They speculate, that this decrease in Sr-87/Sr-86 may have been related to massive dissolution of older carbonate on the sea floor associated with NH2B (Neogene Hiatus 2 of Keller and Barron, 1983). This event may have important implications for changes in carbonate chemistry of the oceans. Numerical modeling of the strontium isotope budget will be used to test the feasibility of this mechanism and to estimate the volume and age of dissolved carbonate needed to produce the observed decrease in Sr-87/Sr-86.

  18. The Cenozoic Diversity of Agglutinated Foraminifera - Evidence for a late Oligocene to early Miocene diversification event

    NASA Astrophysics Data System (ADS)

    Kaminski, Michael; Setoyama, Eiichi; Kender, Sev; Cetean, Claudia

    2014-05-01

    The agglutinated foraminifera are among the most abundant micro-organisms in the deep marine environment and have a diversity record extending back to the late Precambrian. We present an updated diversity curve for agglutinated foraminiferal genera based on the stratigraphic ranges of all the agglutinated genera recognized as valid in the classification of Kaminski (2014). The data set for this analysis is based on the stratigraphic ranges of agglutinated genera published in Foraminiferal Genera and their Classification, which has been subsequently updated based on published studies and our new observations. The mean standing diversity of agglutinated foraminiferal genera was compiled by counting the number of boundary crossers rather than the number of genera in each stage. In this study, we report the stratigraphic and geographical occurrence of a benthic foraminiferal diversification event that has previously received little attention. In the latest Oligocene to earliest Miocene a number of trochospiral agglutinated genera with alveolar or canaliculate walls first appeared in the fossil record. Our studies of late Oligocene of the Congo fan, offshore Angola (Kender et al., 2008; Cetean and Kaminski, 2011) have revealed a diverse assemblage that includes new taxa of deep-water agglutinated foraminifera. In a biostratigraphic study of the Miocene foraminiferal assemblages Kender et al. (2008) noted steadily increasing diversity and proportions of infaunal agglutinated foraminiferal morphotypes over the lower Miocene interval. The proportion of infaunal agglutinated foraminifera assigned to the order Textularida increased dramatically in the lower mid-Miocene, suggesting expansion of the oxygen minimum zone into deeper waters. In addition to the trochospiral alveolar genera, several species of Reticulophragmium and Cyclammina display rapid diversification into numerous separate lineages that are at present not reflected in our generic diversity record owing to their poorly established taxonomy. Genera such as Alveovalvulina, Guppyella, Goesella, and Alveovalvulinella, are typical of assemblages found in subtropical oxygen minimum zones, especially in West Africa and the Caribbean. These agglutinated genera are not found in coeval assemblages from the northern high latitudes (Kaminski et al. 2005), suggesting they are restricted to the low-latitude OMZ. It is likely that the global warming of the latest Oligocene to Early Miocene contributed to intensification of dysoxic conditions in low-latitude upwelling regions, possibly from enhanced productivity and reduced deep-sea ventilation, creating an expanded niche for these organisms that flourished in low-oxygen conditions with high particulate organic matter input. We believe a more detailed phylogenetic approach to these agglutinated genera would result in the description of new genera for individual lineages and refinement of the foraminiferal diversity record.

  19. An objective statistical test for eccentricity forcing of Oligo-Miocene climate

    NASA Astrophysics Data System (ADS)

    Proistosescu, C.; Huybers, P.; Maloof, A. C.

    2008-12-01

    We seek a maximally objective test for the presence of orbital features in Oligocene and Miocene ?18O records from marine sediments. Changes in Earth's orbital eccentricity are thought to be an important control on the long term variability of climate during the Oligocene and Miocene Epochs. However, such an important control from eccentricity is surprising because eccentricity has relatively little influence on Earth's annual average insolation budget. Nevertheless, if significant eccentricity variability is present, it would provide important insight into the operation of the climate system at long timescales. Here we use previously published data, but using a chronology which is initially independent of orbital assumptions, to test for the presence of eccentricity period variability in the Oligocene/Miocene sediment records. In contrast to the sawtooth climate record of the Pleistocene, the Oligocene and Miocene climate record appears smooth and symmetric and does not reset itself every hundred thousand years. This smooth variation, as well as the time interval spanning many eccentricity periods makes Oligocene and Miocene paleorecords very suitable for evaluating the importance of eccentricity forcing. First, we construct time scales depending only upon the ages of geomagnetic reversals with intervening ages linearly interpolated with depth. Such a single age-depth relationship is, however, too uncertain to assess whether orbital features are present. Thus, we construct a second depth-derived age-model by averaging ages across multiple sediment cores which have, at least partly, independent accumulation rate histories. But ages are still too uncertain to permit unambiguous detection of orbital variability. Thus we employ limited tuning assumptions and measure the degree by orbital period variability increases using spectral power estimates. By tuning we know that we are biasing the record toward showing orbital variations, but we account for this bias in our statistical assessment of the significance of these orbital features. We use synthetic data with a priori known spectrum to model the effect our tuning algorithm has on the data, estimating how much power can be induced at eccentricity periods by tuning. In addition, we explore the implications of tuning only to obliquity or precession for the power concentrated at eccentricity periods.

  20. Palaeoecological construction from the Oligo-Miocene coal deposits of Gelibolu Peninsula, NW Turkey.

    NASA Astrophysics Data System (ADS)

    Demirta?, Ferdi; Ko?un, Erdal; Serkan Akkiraz, Mehmet; Bozcu, Mustafa; Koç, Koray

    2015-04-01

    The palynomorph composition of the Upper Oligocene and Miocene coal deposits from Gelibolu peninsula, NW Turkey, was analyzed to determine the palaeoclimate conditions. The samples were collected from two different abandoned coal mines. Also two different palynological assemblages were reported. The first one belongs to the Late Oligocene (Osmancik Formation). The other one is the Miocene (Gazhanedere Formation). The Late Oligocene palynological assemblage consist mainly of Alnus, Myricaceae, Cyrillaceae-Clethraceae, Calamus and Castanea. Riparian vegetation or wetland forest community incorporate high amounts of Alnus, and low percentages of deciduous Salix, Pterocarya and Carya. Calamus, which is a stratigraphical marker for the Late Oligocene of the Thrace Basin, was also recorded in high quantities. The content of the Miocene palynological assemblage is different from the Late Oligocene assemblage, and is mainly made up of Polypodiaceae, Poaceae, Chenopodiaceae, Myricaceae, Oleaceae, Cyrillaceae-Clethraceae and Sapotaceae. Calamus and Alnus totally disappear here. In contrast, open vegetation elements such Poaceae and Chenopodiaceae occur frequently. The palaeoclimate calculations were made by the help of coexistence approach method. The late Oligocene association contains a total of 18 taxa, 11 of which were used for calculating the coexistence intervals. The values obtained 15.6 to 21.1 ° C for annual temperature, 5.0 to 13.3 ° C for winter temperature, 24.7 to 28.1 ° C for summer temperature and, 1096 to 1355 mm annual rainfall. In the Miocene palynological assemblage 23 taxa were identified. The palaeoclimate calculation is based on the 21 taxa. Quantitative data indicate the values for the mean annual temperature 15.6-21.3 ° C, for the winter temperature 5.0 to 13.3 ° C, 24.7- 27.9 ° C for summer temperature and 823-1520 mm for the annual rainfall. The palaeoclimate was warm and contained dry seasons due to lower boundary of annual precipitation lying at 823 mm during the Miocene. This may be linked ecological dominance of open-habitat grasses such as Poaceae and Chenopodiaceae.

  1. Paleomagnetic quantification of upper-plate deformation during Miocene detachment faulting in the Mohave Mountains, Arizona

    USGS Publications Warehouse

    Pease, V.; Hillhouse, J.W.; Wells, R.E.

    2005-01-01

    Paleomagnetic data from Miocene (???20 Ma) volcanic rocks and dikes of west central Arizona reveal the tilt history of Proterozoic crystalline rocks in the hanging wall of the Chemehuevi-Whipple Mountains detachment fault. We obtained magnetization data from dikes and flows in two structural blocks encompassing Crossman Peak and Standard Wash in the Mohave Mountains. In the Crossman block the dike swarm records two components of primary magnetization: (1) CNH, a normal polarity, high-unblocking-temperature or high-coercivity component (inclination, I = 48.5??, declination, D = 6.4??), and (2) CRHm, a reversed polarity, high-temperature or high-coercivity component (I = -33.6??, D = 197.5??). Argon age spectra imply that the dikes have not been reheated above 300??C since their emplacement, and a baked-contact test suggests that the magnetization is likely to be Miocene in age. CRHm deviates from the expected direction of the Miocene axial dipole field and is best explained as a result of progressive tilting about the strike of the overlying andesite flows. These data suggest that the Crossman block was tilted 60?? to the southwest prior to intrusion of the vertical dike swarm, and the block continued to tilt during a magnetic field reversal to normal polarity (CNH). Miocene dikes in the Crossman block are roughly coplanar, so the younger dikes with normal polarity magnetization intruded along planes of weakness parallel to the earlier reversed polarity swarm. An alternative explanation involves CNH magnetization being acquired later during hydrothermal alteration associated with the final stages of dike emplacement. In the Standard Wash block, the primary component of magnetization is a dual-polarity, high-temperature or high-coercivity component (SWHl, I = 7.2??,D= 0.7??). To produce agreement between the expected Miocene magnetic direction and the SWH component requires (1) correcting for a 56?? tilt about the strike of flow bedding and (2) removing a counterclockwise vertical-axis rotation of 20??. The two rotations restore the Standard Wash dikes to vertical, make parallel the dike layering in the Crossman and Standard Wash blocks, and align the strikes of bedding in both blocks. Geologic mapping, geochemical evidence, and paleomagnetic data are consistent with the upper plate of the Mohave Mountains having tilted in response to formation of the underlying detachment fault.

  2. Palynology, paleoclimatology and correlation of middle Miocene beds from Porcupine River (locality 90-1), Alaska

    USGS Publications Warehouse

    White, J.M.; Ager, T.A.

    1994-01-01

    Beds in the Upper Ramparts Canyon of the Porcupine River, Alaska (67?? 20' N, 141?? 20' W), yielded a flora rich in pollen of hardwood genera now found in the temperate climates of North America and Asia. The beds are overlain or enclosed by two basalt flows which were dated to 15.2 ?? 0.1 Ma by the 40Ar 39Ar method, fixing the period of the greatest abundance of warm-loving genera to the early part of the middle Miocene. The assemblage is the most northern middle Miocene flora known in Alaska. Organic bed 1 underlies the basalt and is older than 15.2 Ma, but is of early to middle Miocene age. The pollen assemblage from organic bed 1 is dominated by conifer pollen from the pine and redwood-cypress-yew families with rare occurrences of temperate hardwoods. Organic bed 2 is a forest floor containing redwood trees in life position, engulfed by the lowest basalt flow. A pine log has growth rings up to 1 cm thick. Organic beds 3 and 4 comprise lacustrine sediment and peat between the two basalt flows. Their palynoflora contain conifers and hardwood genera, of which about 40% have modern temperate climatic affinities. Hickory, katsura, walnut, sweet gum, wingnut, basswood and elm pollen are consistently present, and beech and oak alone make up about 20% of the pollen assemblage. A warm high latitude climate is indicated for all of the organic beds, but organic bed 3 was deposited under a time of peak warmth. Climate data derived by comparison with modern east Asian vegetation suggest that, at the time of deposition of organic bed 3, the Mean Annual Temperature (MAT) was ca. 9??C, the Warm Month Mean Temperature (WMMT) was ??? 20??C and the Cold Month Mean Temperature (CMMT) was ca. -2??C. In contrast, the modern MAT for the region is -8.6??C, WMMT is 12.6??C and CMMT is -28??C. Organic beds 3 and 4 correlate to rocks of the middle Miocene-late Seldovian Stage of Cook Inlet and also probably correlate to, and more precisely date, the lower third of the Suntrana Formation in the Alaska Range, beds at Unalaklect, part of the upper Mackenzie Bay sequence in the Beaufort-Mackenzie basin, and the Mary Sachs gravel of Banks Island. This suggests that forests with significant percentages of temperate deciduous angiosperms existed between latitudes 60?? and 72??N during the early middle Miocene. ?? 1994.

  3. S concentrations and its speciation in Miocene basaltic magmas north and south of Gran Canaria (Canary Islands): constraints from glass inclusions in olivine and clinopyroxene

    NASA Astrophysics Data System (ADS)

    Gurenko, Andrey A.; Schmincke, Hans-Ulrich

    2000-07-01

    We report S concentrations and relative proportions of SO 42- and S 2- in OL- and CPX-hosted glass inclusions and in host glassy lapilli from Miocene basaltic hyaloclastites drilled north and south of Gran Canaria during ODP Leg 157. Compositions of glass inclusions and lapilli resemble those of subaerial Miocene shield basalts on Gran Canaria and comprise mafic to more evolved tholeiitic to alkali basalt and basanite (10.3-3.7 wt.% MgO, 44.5-56.9 wt.% SiO 2). Glass inclusions fall into three groups based on their S concentrations: a high-sulfur group (1050 to 5810 ppm S), an intermediate-sulfur group (510 to 1740 ppm S), and a low-sulfur group (<500 ppm S). The most S-rich inclusions have the highest and nearly constant proportion of sulfur dissolved as sulfate determined by electron microprobe measurements of S K? peak shift. Their average S 6+/S total value is 0.75 ± 0.09, unusually high for ocean island basalt magmas. The low-sulfur group inclusions have low S 6+/S total ratios (0.08 ± 0.05), whereas intermediate sulfur group inclusions show a wide range of S 6+/S total (0.05-0.83). Glassy lapilli and their crystal-hosted glass inclusions with S concentrations of 50 to 1140 ppm S have very similar S 6+/S total ratios of 0.36 ± 0.06 implying that sulfur degassing does not affect the proportion of SO 42- and S 2- in the magma. The oxygen fugacities estimated from S 6+/S total ratios and from Fe 3+/Fe 2+ ratios in spinel inclusions range from NNO-1.1 to NNO+1.8. The origin of S-rich magmas is unclear. We discuss (1) partial melting of a mantle source at relatively oxidized fO 2 conditions, and (2) magma contamination by seawater either directly or through magma interaction with seawater-altered Jurassic oceanic crust. The intermediate sulfur group inclusions represent undegassed or slightly degassed magmas similar to submarine OIB glasses, whereas the low-sulfur group inclusions are likely to have formed from magmas significantly degassed in near-surface reservoirs. Mixing of these degassed magmas with stored volatile-rich ones or volatile-rich magma replenishing the chamber filled by partially degassed magmas may produce hybrid melts with strongly varying S concentrations and S 6+/S total ratios.

  4. Late cenozoic evolution of Fortymile Ash: Major change in drainage pattern in the Yucca Mountain, Nevada region during late miocene volcanism

    SciTech Connect

    Lundstrom, S.C. [Geological Survey, Las Vegas, NV (United States); Warren, R.G. [Los Alamos National Lab., NM (United States)

    1994-12-31

    Analysis of sedimentary provenance and altitude distribution of volcanic strata along Fortymile Wash, the primary desert wash east of Yucca Mountain, NV, indicates a major change in surface drainage basins related to late Miocene volcanic disruption. This event resulted in the establishment of the modern Fortymile Wash basin before 3 Ma, and probably by latest Miocene time. An understanding of this event is useful for evaluation of extensive alluviation east of Yucca Mountain and its relation to paleoclimate, hydrology and tectonics. To the northeast of Yucca Mountain, Fortymile Wash provides southward surface drainage from 60% of the area of the 11 Ma Timber Mountain caldera via Fortymile Canyon, a major breach in the caldera wall. In the southeast caldera moat, the distribution of volcanic units that predate and include the 9.4 Ma Thirsty Canyon Group and the characteristics of intercalated sediments indicate a northward paleoslope and sediment transport from a major drainage divide near Dome Mountain, a shield volcano now deeply incised by Fortymile Canyon. Eruption of the Thirsty Canyon Group from the Black Mountain area, 10 km northwest of the Timber Mountain caldera, is likely to have dammed a counterclockwise drainage system of the east moat. Following drainage disruption, the east moat filled with sediment up to the level of a new southward outlet at the saddle between Dome Mountain and the onlapping rhyolite of Shoshone Mountain. An older canyon south of this saddle received the overflow from the east moat and became the throughgoing Fortymile Canyon, integrating the east moat basin with a lower base level in Jackass Flats. Well-integrated southward drainage existed by the time the trachybasalt flows of Buckboard Mesa (2.8 Ma) were emplaced, because basal elevations of these flows slope southward about 100 m above modern Fortymile Wash.

  5. Evidence for Late Oligocene-Early Miocene episode of transtension along San Andreas Fault system in central California

    SciTech Connect

    Stanley, R.G.

    1986-04-01

    The San Andreas is one of the most intensely studied fault systems in the world, but many aspects of its kinematic history remain controversial. For example, the period from the late Eocene to early Miocene is widely believed to have been a time of negligible strike-slip movement along the San Andreas fault proper, based on the rough similarity of offset of the Eocene Butano-Point of rocks Submarine Fan, the early Miocene Pinnacles-Neenach volcanic center, and an early Miocene shoreline in the northern Gabilan Range and San Emigdio Mountains. Nonetheless, evidence indicates that a late Oligocene-early Miocene episode of transtension, or strike-slip motion with a component of extension, occurred within the San Andreas fault system. The evidence includes: (1) about 22-24 Ma, widespread, synchronous volcanic activity occurred at about 12 volcanic centers along a 400-km long segment of the central California coast; (2) most of these volcanic centers are located along faults of the San Andreas system, including the San Andreas fault proper, the San Gregorio-Hosgri fault, and the Zayante-Vergeles fault, suggesting that these and other faults were active and served as conduits for magmas rising from below; (3) during the late Oligocene and early Miocene, a pull-apart basin developed adjacent to the San Andreas fault proper in the La Honda basin near Santa Cruz; and (4) during the late Oligocene and early Miocene, active faulting, rapid subsidence, and marine transgression occurred in the La Honda and other sedimentary basins in central California. The amount of right-lateral displacement along the San Andreas fault proper during this transtentional episode is unknown but was probably about 7.5-35 km, based on model studies of pull-apart basin formation. This small amount of movement is well within the range of error in published estimates of the offset of the Eocene to early Miocene geologic features noted.

  6. Fission track evidence for widespread early to Middle miocene extension in the northern Basin and Range province

    SciTech Connect

    Dumitru, T.; Miller, E.; Savage, C. (Stanford Univ., CA (United States). Geological Dept.); Gans, P. (Univ. of California, Santa Barbara, CA (United States). Geological Science Dept.); Brown, R. (La Trobe Univ., Bundoora, Victoria (Australia). Geology Dept.)

    1993-04-01

    The northern Basin and Range province has experienced multiple periods of extension but the precise timing and relative importance of the various periods is poorly known. Geologic data in many areas suggest inception of extension was closely tied with the southward sweep in earliest magmatism, which is Eocene in southern Idaho, Oligocene in east-central Nevada, and Miocene in southern Nevada. Ar/Ar ages suggest that extension continued into the Early Miocene in areas such as the Raft River, Albion, Ruby, and Snake Range metamorphic core complexes. Youthful topography and recent faulting have been taken as indicating that faulting leading to present physiography is commonly younger than [approximately]10 Ma. New apatite fission track cooling age and track length data, supplemented by other information, point to the Early to Middle Miocene as an additional time of very significant extension-induced uplift and range formation. Many ranges in a 700-km-long north-south corridor from the Utah-Nevada-Idaho border to southernmost Nevada experience extension and major exhumation in Early to Middle Miocene time. Whether extension of Early to Middle Miocene age is restricted to this corridor or is more widespread is unclear due to the paucity of similar data to the east and west. Reconnaissance apatite ages from the Toiyabe Range and environs (NV) are [approximately]15 Ma and geologic data indicate Early to Middle Miocene extension at Yerington NV (Proffet and Dillis, 1984). Thus, it appears from the available data that the Early to Middle Miocene was an important, and previously little recognized, period of major extension over broad areas of the northern Basin and Range.

  7. Miocene and Pliocene lacustrine and fluvial sequences, Upper Ramparts and Canyon village, Porcupine river, east-central Alaska

    USGS Publications Warehouse

    Fouch, T.D.; Carter, L.D.; Kunk, M.J.; Smith, C.A.S.; White, J.M.

    1994-01-01

    Cenozoic strata exposed along the Porcupine River between the Upper Ramparts and Canyon Village, Alaska, can be divided into five unconformity-bounded units (sequences) which are: lower and middle Miocene unit A, the white sandy fluvial sequence with peat beds; middle Miocene unit B, the basalt sequence-part B1 is basalt, and part B2 is organic-rich sedimentary beds; upper Miocene unit C, mudrock-dominated lake sequence; late Miocene or Pliocene to Pleistocene unit D, terrace gravels, detrital organic matter and associated sediments, and Holocene unit E, mixed sand and gravel-rich sediment and other sedimentary material including peat and eolian silt. The sequence (unit A) of lower and middle Miocene fluvial deposits formed in streams and on flood plains, just before the inception of local volanism. Fossil pollen from unit A suggests conifer-dominated regional forests and cool temperate climates. Peat beds and lake deposits from unit B contain pollen that indicates a warmer temperate climate coinciding with the middle Miocene thermal maximum. The lake deposits (unit C) downstream from the basalts accumulated in a small basin which resulted from a hydrologic system that was dammed in the late Miocene but breached soon thereafter. The lower part of the terrace gravels (unit D) expresses breaching of the dammed hydrologic system (of unit C). The Porcupine River became a major tributary of the Yukon River in late Pleistocene time when Laurentide ice blocked drainage from the Yukon interior basins causing meltwater to spill over the low divide separating it from the Porcupine River drainage initiating erosion and capture of the Yukon interior basins. ?? 1994.

  8. Depositional patterns and hydrocarbon occurrence in middle to upper Miocene strata in part of the western Niger Delta Basin, Nigeria

    NASA Astrophysics Data System (ADS)

    Agyingi, C. M.; Agagu, O. K.; Fozao, K. F.; Njoh, O. A.; Ngalla, N.

    2013-04-01

    The relation of depositional patterns to hydrocarbon occurrence in middle to upper Miocene strata of part of the western Niger Delta Basin is postulated from the study of electrical logs, radiometric logs, lithologic logs, bottom hole temperatures, intervals of hydrocarbon occurrence and paleontological data. Alternating sands and shales of the Agbada Formation were deposited in the area (up to 720 m, middle Miocene and 510 m, upper Miocene) mainly as regressive off lap sequences in a paralic environment with depo-centers located in the south of the study area. Three deltaic facies can be recognized based on the relative amounts of shale and sand including, proximal delta front facies (>70% sand), distal delta front facies (30-70% sand) and prodelta facies (<30% sand). The upper Miocene is generally sandier than the middle Miocene as a result of south-westerly progradation of delta front facies from middle to upper Miocene. Geothermal gradients in the area range from 2.5 °C/100 m to 4.4 °C/100 m. Isothermal maps show that some middle to upper Miocene shales could have undergone catagenesis to become mature source rocks. Three depositional zones (A, B, C) corresponding to dominant depositional facies i.e., proximal delta, distal delta and prodelta respectively, have been delineated from sand percentage maps. There is a progression of these zones from A through B to C in a generally south-westerly direction (the direction of delta progradation). Data for hydrocarbon intervals reveal the predominance of hydrocarbons in Zone C due to high entrapment potentials and to a lesser extent in Zone B. Zone A is barren as a result of poor entrapment potentials. The juxtaposition of distal delta front sands and prodelta mud could have initiated growth faults which constitute the major types of traps in the basin.

  9. Early to middle Miocene vegetation history of Antarctica supports eccentricity-paced warming intervals during the Antarctic icehouse phase

    NASA Astrophysics Data System (ADS)

    Griener, Kathryn W.; Warny, Sophie; Askin, Rosemary; Acton, Gary

    2015-04-01

    Recent palynological evidence from the upper section (< 664 mbsf) of the Miocene ANDRILL 2A (AND-2A) core in the Ross Sea indicated a brief warm period during the Mid Miocene Climatic Optimum (MMCO), during Antarctica's icehouse phase. The nature of other Miocene climate fluctuations in Antarctica remains poorly resolved. Here, we present new palynological data from the lower section of the AND-2A core (> 664 mbsf) that reveal additional intervals of increased palynomorph abundance and diversity during the Antarctic early to middle Miocene. This evidence is consistent with a relatively dynamic early Miocene Antarctic icehouse climate with intervals of increased temperature and moisture, prior to the MMCO. Comparison with previous AND-2A studies indicates that periods of increased palynomorph abundance in the lower stratigraphic section largely coincide with ice sheet minima, distal ice conditions, and the presence of freshwater (i.e. increased precipitation, meltwater run-off, and freshwater ponds). Decreases in plant productivity mostly coincide with increased glaciation, decreased freshwater, and ice-proximal conditions during the Antarctic Miocene. Comparing the palynological data with other AND-2A data and global climate proxies (e.g., pCO2, ?18O, relative sea level, Milankovitch cycles) helps to resolve questions regarding the driving forces behind climate and vegetation change. We found that palynomorph assemblages reflecting generally warmer conditions are largely associated with 400-kyr eccentricity maxima, while assemblages indicative of colder conditions coincide with 400-kyr eccentricity minima. These data are consistent with other findings that indicate the early to middle Miocene climate was eccentricity-paced.

  10. Eocene to Miocene Southern Ocean Circulation: Neodymium Records from Fossil Fish Teeth

    NASA Astrophysics Data System (ADS)

    Scher, H. D.; Martin, E. E.

    2003-04-01

    The Eocene to Miocene was a period of dramatic changes to ocean circulation, which have been linked to major shifts in global climate. Evolution of the Southern Ocean had a powerful influence over patterns of ocean circulation during this time. Pre-Miocene seawater Nd isotope records, proxies for water mass used to reconstruct paleocean circulation, are poorly represented in the Southern Ocean. Here we supplement the small, but growing, Nd isotope database with two long-term Nd records from fossil fish teeth in ODP sites 689 (Maud Rise, 2080 m) and 1090 (Aghulas Ridge, 3702 m), both located in the Southern Ocean. ?{Nd} values from site 689 range from -8 at 35 Ma to -9.1 at 20 Ma. The intermediate water mass at this site was at least 1 ?{Nd} lower than the deep water mass at site 1090 throughout the late Eocene to early Miocene with the exception of a brief interval at ˜26 Ma, when increasing values at site 689 overlap with decreasing values at site 1090. Site 1090 ?{Nd} values are dominated by a decreasing trend during the Oligocene when ?{Nd} values of -6.5 at 28.5 Ma decrease to -8.5 by 22 Ma. This long-term trend is punctuated by a rapid negative oscillation of 2 ?{Nd} at ˜26 Ma and a rapid positive oscillation of 1 ?{Nd} at ˜23 Ma. ?{Nd} values at site 1090 then increase by 1 ?{Nd} during the early to mid-Miocene. Together sites 689 and 1090 illustrate an ?{Nd} depth profile that becomes more radiogenic with depth, which is opposite to the present-day Atlantic, Indian, and Pacific oceans. This gradient persists through the late Eocene to Miocene except at ˜26 Ma when the difference in ?{Nd} between the two sites diminishes to .4, suggesting a water mass between -8.1 and -8.5 ?{Nd} at both sites. Tethyan waters have been characterized as having ?{Nd} in this range during the Oligocene/Miocene. A brief pulse of Warm Saline Bottom Water emanating from the Tethyan region may be responsible for rapid oscillations in Southern Ocean Nd records. The coincidence of these oscillations with the Late Oligocene Warming event (˜26 Ma) recognized in global ?18O records (including site 689) supports this interpretation. The only known potential source of radiogenic water necessary to bring ?{Nd} values at site 1090 as high as -6.5 were Pacific source waters which ranged from -6.5 to -4 in the Oligocene/Miocene. We believe that site 1090 Nd isotopes provide evidence for transport of Pacific seawater through the Drake Passage by at least 28.5 Ma. Nonradiogenic ?{Nd} values at site 689 are consistent with the presence of an intermediate to deep water mass sourced near Antarctica.

  11. Scappoose Formation, Columbia County, Oregon: new evidence of age and relation to Columbia River basalt group

    Microsoft Academic Search

    R. O. VanAtta; K. B. Kelty

    1985-01-01

    The Scappoose Formation, considered to be late Oligocene to early Miocene in age, was originally believed to be disconformably separated from both the underlying Pittsburg Bluff Formation and the overlying Yakima subgroup of the Columbia River Basalt Group. Recent mapping and petrography show that it lies disconformably on both the Keasey and Pittsburg Bluff Formations, and interfingers with the Yakima

  12. Dated molecular phylogenies indicate a Miocene origin for Arabidopsis thaliana.

    PubMed

    Beilstein, Mark A; Nagalingum, Nathalie S; Clements, Mark D; Manchester, Steven R; Mathews, Sarah

    2010-10-26

    Dated molecular phylogenies are the basis for understanding species diversity and for linking changes in rates of diversification with historical events such as restructuring in developmental pathways, genome doubling, or dispersal onto a new continent. Valid fossil calibration points are essential to the accurate estimation of divergence dates, but for many groups of flowering plants fossil evidence is unavailable or limited. Arabidopsis thaliana, the primary genetic model in plant biology and the first plant to have its entire genome sequenced, belongs to one such group, the plant family Brassicaceae. Thus, the timing of A. thaliana evolution and the history of its genome have been controversial. We bring previously overlooked fossil evidence to bear on these questions and find the split between A. thaliana and Arabidopsis lyrata occurred about 13 Mya, and that the split between Arabidopsis and the Brassica complex (broccoli, cabbage, canola) occurred about 43 Mya. These estimates, which are two- to threefold older than previous estimates, indicate that gene, genomic, and developmental evolution occurred much more slowly than previously hypothesized and that Arabidopsis evolved during a period of warming rather than of cooling. We detected a 2- to 10-fold shift in species diversification rates on the branch uniting Brassicaceae with its sister families. The timing of this shift suggests a possible impact of the Cretaceous-Paleogene mass extinction on their radiation and that Brassicales codiversified with pierid butterflies that specialize on mustard-oil-producing plants. PMID:20921408

  13. Dated molecular phylogenies indicate a Miocene origin for Arabidopsis thaliana

    PubMed Central

    Beilstein, Mark A.; Nagalingum, Nathalie S.; Clements, Mark D.; Manchester, Steven R.; Mathews, Sarah

    2010-01-01

    Dated molecular phylogenies are the basis for understanding species diversity and for linking changes in rates of diversification with historical events such as restructuring in developmental pathways, genome doubling, or dispersal onto a new continent. Valid fossil calibration points are essential to the accurate estimation of divergence dates, but for many groups of flowering plants fossil evidence is unavailable or limited. Arabidopsis thaliana, the primary genetic model in plant biology and the first plant to have its entire genome sequenced, belongs to one such group, the plant family Brassicaceae. Thus, the timing of A. thaliana evolution and the history of its genome have been controversial. We bring previously overlooked fossil evidence to bear on these questions and find the split between A. thaliana and Arabidopsis lyrata occurred about 13 Mya, and that the split between Arabidopsis and the Brassica complex (broccoli, cabbage, canola) occurred about 43 Mya. These estimates, which are two- to threefold older than previous estimates, indicate that gene, genomic, and developmental evolution occurred much more slowly than previously hypothesized and that Arabidopsis evolved during a period of warming rather than of cooling. We detected a 2- to 10-fold shift in species diversification rates on the branch uniting Brassicaceae with its sister families. The timing of this shift suggests a possible impact of the Cretaceous–Paleogene mass extinction on their radiation and that Brassicales codiversified with pierid butterflies that specialize on mustard-oil–producing plants. PMID:20921408

  14. Mitochondrial relationships and divergence dates of the African colobines: evidence of Miocene origins for the living colobus monkeys.

    PubMed

    Ting, Nelson

    2008-08-01

    The African colobines represent a neglected area of cercopithecid systematics. Resolving the phylogenetic relationships and estimating divergence dates among the living forms will provide insight into the evolution of this group and may shed light upon the evolution of other African primates as well. This is the first molecular assessment of the evolutionary relationships among the modern colobus monkeys, which are comprised of the black-and-white, olive, and red colobus groups. Over 4,000 base pairs of mitochondrial DNA were amplified and sequenced in over 40 colobus monkey individuals incorporating representatives from all commonly recognized species. Gene trees were inferred using maximum likelihood and Bayesian inference, and penalized likelihood was employed to estimate mitochondrial divergence dates among the sampled taxa. The results are congruent with some aspects of previous phylogenetic hypotheses based on morphology and vocalizations, although the relationships among several West and Central African taxa differ to some degree. The divergence date analysis suggests that the black-and-white, olive, and red colobus had diverged from one another by the end of the Miocene, and that by the Plio-Pleistocene many of the species lineages were already present. This demonstrates that the initial extant colobus monkey diversification occurred much earlier than previously thought and was likely part of the same adaptive radiation that produced the diverse colobine taxa seen in the African Plio-Pleistocene fossil record. The lack of early members from the modern lineages in fossiliferous deposits suggests that they resided in part in the forests of Central and West Africa, which also currently harbor the highest levels of colobus monkey diversity. These forests should not be ignored in models of Plio-Pleistocene human and nonhuman primate evolution. PMID:18423802

  15. A Calcium Isotope Record from the Miocene of the Kerguelen Plateau (Southern Indian Ocean) - Global or Local Signal?

    NASA Astrophysics Data System (ADS)

    Heuser, A.; Boehm, F.; Eisenhauer, A.; Dullo, W.

    2001-05-01

    The Kerguelen Plateau is a mostly drowned oceanic plateau in the Indian sector of the Southern Ocean. It formed during the late Cretaceous as a temporarily subaerial volcanic plateau. Today most of the plateau is situated south of the polar front and many parts are at water depths of less than 2000 m. Several holes drilled during ODP Legs 119, 120 and 183 offer the opportunity to study Miocene sedimentary sequences from a southern high latitude setting. The Miocene of the Kerguelen Plateau shows a pronounced facies shift from carbonate dominated sediments in the Early and Middle Miocene to opaline and volcanoclastic domination in the Pliocene and Pleistocene. The facies transition started during the Late Miocene, when around 11 Ma carbonate accumulation rates began to decline. A short period of lowered carbonate contents at about 8.5 to 9.5 Ma may be an expression of the Late Miocene "carbonate crash". During the transitional time hiatuses were widespread and there appears to exist no sedimentary record from about 4.5 to 7 Ma, when a major hiatus formed at all investigated sites. Almost pure diatom oozes were deposited at the southern sites during the latest Miocene and in the Pliocene. At the more northern sites, however, there is sufficient carbonate during this time to allow almost continuous sampling of carbonate components from Early Miocene through Pleistocene. We collected planktonic foraminifera from the most continuous record, cored at ODP Site 1138, at a resolution of about 1 Ma from Late Miocene to Pleistocene for determination of calcium and strontium isotope ratios. Our calcium isotope record correlates well with the data of De La Rocha & DePaolo (2000, Science 289, 1176-1178). Our better temporal resolution allows to date the Middle Miocene calcium isotope minimum as 15 Ma. Comparison with a benthic foraminifera oxygen isotope record from the nearby ODP site 747 (Wright & Miller 1992, Proc. ODP Sci. Res. 120, 855-866) shows a parallel rise of calcium and oxygen isotopes from the minimum at 15 Ma to a Late Miocene maximum at about 7 Ma. Comparing calcium and strontium isotope records, we find that the the minimum further correlates with the well known Middle Miocene inflection in the seawater strontium isotope curve. During the Pliocene/Pleistocene cooling no correlation between oxygen and calcium isotopes can be observed. Thus, it is not possible to explain our observations by local temperature effects. More likely, the calcium isotope record reflects global changes in the oceanic calcium reservoir through changing weathering fluxes or dissolution and deposition of calcium carbonates. If this is the case, global events like the Late Miocene "carbonate crash" or the Miocene/Pliocene lowering of the carbonate compensation depth should have left traces in the calcium isotope record as recorded in planktonic foraminifera.

  16. Petrology of the Miocene igneous rocks in the Altar region, main Cordillera of San Juan, Argentina. A geodynamic model within the context of the Andean flat-slab segment and metallogenesis

    NASA Astrophysics Data System (ADS)

    Maydagán, Laura; Franchini, Marta; Chiaradia, Massimo; Pons, Josefina; Impiccini, Agnes; Toohey, Jeff; Rey, Roger

    2011-07-01

    The Altar porphyry Cu-(Au-Mo) deposit (31° 29' S, 70° 28' W) is located in the Andean Main Cordillera of San Juan Province (Argentina), in the southern portion of the flat-slab segment (28-33°S), 25 km north of the world-class porphyry Cu-Mo deposits of Los Pelambres and El Pachón. Igneous rocks in the area have been grouped into the Early Miocene Lower Volcanic Complex -composed of intercalations of lava flows and thin volcaniclastic units that grade upwards to a thick massive tuff- and the Middle-Late Miocene Upper Subvolcanic Suite that consists of a series of porphyritic stocks and dikes and magmatic and hydrothermal breccias. The Lower Volcanic Complex represents an Early Miocene arc (20.8 Ma ± 0.3 Ma; U-Pb age) erupted over a steep subduction zone. Their magmas equilibrated with an assemblage consisting of plagioclase- and pyroxene-dominated mineral residues, and experienced fractional crystallization and crustal contamination procesess. Their radiogenic signatures are interpreted to indicate conditions of relatively thickened continental crust in Altar during the Early Miocene, compared to the south and west. The Upper Subvolcanic Suite represents the development of a Middle-Late Miocene arc (11.75 ± 0.24 Ma, 10.35 ± 0.32 Ma; U-Pb ages) emplaced over a shallow subduction zone. A magmatic gap in Altar area betwen the Lower Volcanic Complex and Upper Subvolcanic Suite correlates with documented higher rates of compression in this period, that may have favored the storage of the USS magmas in cameras within the crust. Magmas of the Upper Subvolcanic Suite require a hornblende-bearing residual mineral assemblage that is interpreted to reflect their higher water contents. The relatively uniform radiogenic isotope compositions of the Upper Subvolcanic Suite magmas suggest a homogeneously mixed crust-mantle contribution in the source region. They have similar REE signatures as other fertile intrusives of the flat-slab. The differences observed in their isotopic signatures reflect an increase in the amount of crustal components incorporated into magmas from south (El Teniente) to north (El Indio) which correlate with an increase of crustal thickness. U-Pb ages of Altar rocks confirm a temporal connection between the ridge arrival and the magmatism associated with mineralization in this zone of the flat-slab segment. We argue that since the Middle-Late Miocene, mantle and lower crust may have been hydratated by fluids from the slab and from the Juan Fernández Ridge at the latitude of Altar, which favored the generation of the Middle-Late Miocene magmas. We also suggest that at this latitude the collision ridge-trench at ˜11 Ma and the subduction of the Juan Fernández Ridge beneath Altar region at ˜11-10 Ma may have promoted changes in the tectonic stress regime, allowing the USS magmas to rise to shallower levels in the crust. This may explain the location of a cluster of contemporaneous giant porphyry Cu-Mo deposits including El Pachón-Los Pelambres, the Altar Cu (Mo-Au) deposit, and other nearby recently discovered Cu prospects such as Piuquenes, La Coipa, Rincones de Araya and Los Azules.

  17. Middle to late Miocene canyon cutting on the New Jersey continental slope: biostratigraphic and seismic stratigraphic evidence

    SciTech Connect

    Miller, K.G.; Melillo, A.J.; Mountain, G.S.; Farre, J.A.; Poag, C.W.

    1987-06-01

    The authors have identified and dated a major Miocene erosional surface (M1) on the New Jersey continental slope. This surface was penetrated at Deep Sea Drilling Project (DSDP) Site 612, which was drilled near the thalweg of a buried V-shaped canyon. Biostratigraphic data at Site 612 firmly constrain the age of strata above the buried canyon surface as Zones CN7 (N=NN9) and N16 (lowermost upper Miocene); the upper Miocene surface at Site 612 lies above lowermost Oligocene strata because of coalesced unconformities. The authors traced the M1 erosional surface to the COST B-3 well where upper middle Miocene strata underlie it. Biostratigraphic studies of other New Jersey continental slope boreholes (ASP 14, ASP 15) suggest that elsewhere the sediments immediately below the M1 surface encompass the Globorotalia fohsi robusta Zone (=Zone N12-earliest N13; middle middle Miocene). The best age estimate is that M1 was eroded between 11.5 and 10.0 Ma. This erosional event apparently correlates with a similar even on the Irish and Florida continental margins and with oxygen-isotope evidence for a glacio-eustatic lowering.

  18. Combustion Group Group members

    E-print Network

    Wang, Wei

    Combustion Group Group members: Thierry Poinsot, Emilien Courtine, Luc Vervisch, Benjamin Farcy 2014 #12;Combustion Group Combustion Physics and Modeling Pollutants, Emissions, and Soot Formation Thermoacoustics and Combustion Dynamics Research focus § Examine mechanisms responsible for flame stabilization

  19. The Superimposed Paleocene-Miocene Tectonics of the middle part of the Nallihan Wedge (NW Turkey)

    NASA Astrophysics Data System (ADS)

    ?ahin, Murat; Yaltirak, Cenk

    2015-04-01

    In the NW Turkey, the area between the suture zones of the Rhodope-Pontide Ocean and Izmir-Ankara Ocean, and North Anatolian Fault Zone (NAFZ) and Thrace-Eski?ehir Fault Zone (TEFZ) is known as the Nall?han Wedge. The shape of Nall?han Wedge is a 90 degree counter-clockwise rotated isosceles triangle. The northwestern boundary is a part of NAFZ and the southwestern boundary is a part of TEFZ. The 160 km-long eastern boundary is located at around Beypazar? and western corner is on the Bursa Plain. Nall?han is situated at the centre of this isosceles triangle. While all the thrusts and folds shrink towards to the west and show an imbricate-like structure, the characteristics of the folds turn into to the open folds. Thrusts faults are locally observed as blind and almost perpendicular thrusts at the fold limbs towards to the east. The rocks of the study area show different characteristics according to their types and basins of formation. On the other hand the structural properties of these rocks display the effects of the closure of the Intra-Pontide and Izmir-Ankara Oceans in between Paleocene and Early Oligocene. During Miocene, the thrust faults reactivated and a deformation formed the NEE-SWW left lateral strike-slip faults parallel to these thrust faults. Whereas the first events are related to the closure of the branches of Neo-Tethys, the Miocene deformation is probably based on the Miocene tectonics of the Western Anatolia by the reason of equivalent age of the TEFZ. In this framework, the deformation of the Nall?han Wedge presents significant information about the period between the evolution of Paleotectonic and Neotectonic of Turkey.

  20. Ancient Nursery Area for the Extinct Giant Shark Megalodon from the Miocene of Panama

    PubMed Central

    Pimiento, Catalina; Ehret, Dana J.; MacFadden, Bruce J.; Hubbell, Gordon

    2010-01-01

    Background As we know from modern species, nursery areas are essential shark habitats for vulnerable young. Nurseries are typically highly productive, shallow-water habitats that are characterized by the presence of juveniles and neonates. It has been suggested that in these areas, sharks can find ample food resources and protection from predators. Based on the fossil record, we know that the extinct Carcharocles megalodon was the biggest shark that ever lived. Previous proposed paleo-nursery areas for this species were based on the anecdotal presence of juvenile fossil teeth accompanied by fossil marine mammals. We now present the first definitive evidence of ancient nurseries for C. megalodon from the late Miocene of Panama, about 10 million years ago. Methodology/Principal Findings We collected and measured fossil shark teeth of C. megalodon, within the highly productive, shallow marine Gatun Formation from the Miocene of Panama. Surprisingly, and in contrast to other fossil accumulations, the majority of the teeth from Gatun are very small. Here we compare the tooth sizes from the Gatun with specimens from different, but analogous localities. In addition we calculate the total length of the individuals found in Gatun. These comparisons and estimates suggest that the small size of Gatun's C. megalodon is neither related to a small population of this species nor the tooth position within the jaw. Thus, the individuals from Gatun were mostly juveniles and neonates, with estimated body lengths between 2 and 10.5 meters. Conclusions/Significance We propose that the Miocene Gatun Formation represents the first documented paleo-nursery area for C. megalodon from the Neotropics, and one of the few recorded in the fossil record for an extinct selachian. We therefore show that sharks have used nursery areas at least for 10 millions of years as an adaptive strategy during their life histories. PMID:20479893

  1. Paleomagnetic reversals in Miocene dikes, and tectonic evolution of the Crossman block, Mohave Mountains, Arizona

    SciTech Connect

    Nielson, J.E.; Nakata, J.K. (Geological Survey, Menlo Park, CA (United States)); Pease, V.L.

    1993-04-01

    Paleomagnetic data, isotopic ages, and compositions all suggest a common, coeval magmatic source for early Miocene volcanic rocks and a large dike swarm in the Crossman block (CB), central Mohave Mountains, AZ, Colorado River extensional corridor. The CB is a coherent 12-to-15-km-thick piece of crust in the upper plate of the Whipple detachment fault, which tilted by 90 to 100 to the SW in response to movements on the fault. A swarm of early Miocene dikes dip shallowly to the NE, and account for 20% or more of CB thickness. Compositions of dikes and lavas from the CB ranged from basaltic to rhyolitic. A calk-alkaline trend is evident in spite of widespread alteration, and a few of the dikes can be traced into the flow sequence. Reliable dike ages are between 20 and 18 Ma, and those for lavas range from 21.5 to 17.9 Ma. Dikes in the CB show both normal and reversed magnetic polarities contained in high temperature and high coercivity components. Tests of stability in a baked contact supports a Miocene age for the magnetizations. This interpretation supports and adds detail to a two-stage model for tilting of the CB at 19.9[+-]0.5 Ma, based on an unconformity in the volcanic stratigraphy. An explanation for such a rapid tilting of a large crustal fragment may be that friction between lower and upper plate was lowered by a large volumes of magmas that either were generated or ponded at the level of the Whipple detachment fault, at about 20 Ma.

  2. Correlating Mediterranean shallow water deposits with global Oligocene-Miocene stratigraphy and oceanic events

    NASA Astrophysics Data System (ADS)

    Reuter, Markus; Piller, Werner E.; Brandano, Marco; Harzhauser, Mathias

    2013-12-01

    Shallow-marine sediment records have the strong potential to display sensitive environmental changes in sedimentary geometries and skeletal content. However, the time resolution of most neritic carbonate records is not high enough to be compared with climatic events as recorded in the deep-sea sediment archives. In order to resolve the paleoceanographic and paleoclimatic changes during the Oligocene-Miocene transition in the Mediterranean shallow water carbonate systems with the best possible time resolution, we re-evaluated the Decontra section on the Maiella Platform (central Apennines, Italy), which acts as a reference for the correlation of Oligocene-Miocene shallow water deposits in the Mediterranean region. The 120-m-thick late Oligocene-late Miocene carbonate succession is composed of larger foraminiferal, bryozoan and corallinacean limestones interlayered with distinct planktonic foraminiferal carbonates representing a mostly outer neritic setting. Integrated multi-proxy and facies analyses indicate that CaCO3 and total organic carbon contents as well as gamma-ray display only local to regional processes on the carbonate platform and are not suited for stratigraphic correlation on a wider scale. In contrast, new biostratigraphic data correlate the Decontra stable carbon isotope record to the global deep-sea carbon isotope record. This links relative sea level fluctuations, which are reflected by facies and magnetic susceptibility changes, to third-order eustatic cycles. The new integrated bio-, chemo-, and sequence stratigraphic framework enables a more precise timing of environmental changes within the studied time interval and identifies Decontra as an important locality for correlating not only shallow and deep water sediments of the Mediterranean region but also on a global scale.

  3. Correlating Mediterranean shallow water deposits with global Oligocene–Miocene stratigraphy and oceanic events?

    PubMed Central

    Reuter, Markus; Piller, Werner E.; Brandano, Marco; Harzhauser, Mathias

    2013-01-01

    Shallow-marine sediment records have the strong potential to display sensitive environmental changes in sedimentary geometries and skeletal content. However, the time resolution of most neritic carbonate records is not high enough to be compared with climatic events as recorded in the deep-sea sediment archives. In order to resolve the paleoceanographic and paleoclimatic changes during the Oligocene–Miocene transition in the Mediterranean shallow water carbonate systems with the best possible time resolution, we re-evaluated the Decontra section on the Maiella Platform (central Apennines, Italy), which acts as a reference for the correlation of Oligocene–Miocene shallow water deposits in the Mediterranean region. The 120-m-thick late Oligocene–late Miocene carbonate succession is composed of larger foraminiferal, bryozoan and corallinacean limestones interlayered with distinct planktonic foraminiferal carbonates representing a mostly outer neritic setting. Integrated multi-proxy and facies analyses indicate that CaCO3 and total organic carbon contents as well as gamma-ray display only local to regional processes on the carbonate platform and are not suited for stratigraphic correlation on a wider scale. In contrast, new biostratigraphic data correlate the Decontra stable carbon isotope record to the global deep-sea carbon isotope record. This links relative sea level fluctuations, which are reflected by facies and magnetic susceptibility changes, to third-order eustatic cycles. The new integrated bio-, chemo-, and sequence stratigraphic framework enables a more precise timing of environmental changes within the studied time interval and identifies Decontra as an important locality for correlating not only shallow and deep water sediments of the Mediterranean region but also on a global scale. PMID:25844021

  4. Antarctic Ice Sheet dynamics in the Ross Sea during the Early to Middle Miocene

    NASA Astrophysics Data System (ADS)

    Levy, Richard; Harwood, David; Florindo, Fabio; DeConto, Robert; Golledge, Nicholas; Hoffmann, Stefan; Kuhn, Gerhard; McKay, Robert; Naish, Timothy; Pollard, David; Sangiorgi, Francesca; von Eynatten, Hilmar

    2015-04-01

    A 1138-meter sediment core (AND-2A) recovered from the Southern McMurdo Sound sector of the Ross Sea comprises a near-continuous record of Antarctic climate and ice sheet variability through the Early to early Middle Miocene (20.2 to 14.5 million years ago), including an interval of inferred sustained global warmth known as the Miocene Climatic Optimum (MCO). The record preserves 55 sedimentary sequences that reflect cycles of glacial advance and retreat. A new analysis of proxy environmental data from the AND-2A core, and synthesis with regional geological information, show that the early to middle Miocene Antarctic climate ranged from cold polar conditions, similar to Antarctica during the Holocene, to those that characterise modern sub-polar environments. Four disconformities that punctuate the sedimentary sequence coincide with regionally mapped seismic discontinuities and reflect transient expansion of marine-based ice across the Ross Sea. The timing of these major marine-based ice sheet advances correlates with shifts in highly-resolved deep sea isotope records and major drops in eustatic sea-level indicating the global nature of these events. In contrast, three distinct intervals in the core indicate that this high latitude site was periodically influenced by an ice sheet margin that had retreated beyond the coastline. These relatively large-scale changes in climate and ice sheet extent occurred under atmospheric carbon dioxide concentrations that generally varied between 300 to 500 ppm. Therefore, our reconstructions suggest that Antarctica's climate and ice sheets were sensitive to modest changes in greenhouse gas forcing and support previous studies, which indicate that marine-based portions of the WAIS and EAIS can retreat under climatic conditions that were similar to those projected for our future under current levels of atmospheric CO2.

  5. Sedimentary facies, mineralogy, and geochemistry of the sulphate-bearing Miocene Dam Formation in Qatar

    NASA Astrophysics Data System (ADS)

    Dill, H. G.; Botz, R.; Berner, Z.; Stüben, D.; Nasir, S.; Al-Saad, H.

    2005-01-01

    The Miocene deposits of the Dam Formation were deposited in a narrow seaway stretching along the western edge of the Qatar Arch. During the initial stages of basin evolution the rising Zagros Mts. delivered debris in this fore deep basin. The paleocurrent and paleogeographic zonation are reflected by the heavy mineral assemblage, by the spatial distribution of phyllosilicates and the various types of sulphate. From NW towards the SE, the contents of smectite and palygorskite increase, whereas the illite and kaolinite contents decrease. Mega crystals of gypsum are found in the NW and massive fine-grained gypsum in the SE of the basin. During the waning stages of basin subsidence, the Arabian Shield became more and more important as a source for the Miocene sediments. In this study, the Dam Formation was subdivided into 7 members/lithofacies associations (lower, middle, upper Salwa, and Al Nakhsh Members, Abu Samrah Member). The Salwa Members at the base of the Dam Formation consists of heterolithic siliciclastic-calcareous sediments which were laid down under meso- to microtidal conditions. The Al Nakhsh Members formed under macrotidal conditions with sub- to supratidal depositional environments passing into continental ones. Celestite, gypsum, and microbial mats (stromatolites) are very widespread in these sabkha sediments. Crystals of gypsum and the thickness of stromatolites tremendously increase towards younger sediments indicating thereby a close genetic link between growth of microbial domes and gypsum precipitation. Throughout the Abu Samrah Member marine calcareous sediments were deposited in a microtidal wave-dominated environment. Dissolution of Eocene evaporites at depth governed the lithofacies differentiation in the Miocene Dam Formation.

  6. Extrusion vs. duplexing models of Himalayan mountain building 1: Discovery of the Pabbar thrust confirms duplex-dominated growth of the northwestern Indian Himalaya since Mid-Miocene

    NASA Astrophysics Data System (ADS)

    Yu, Hongjiao; Webb, A. Alexander G.; He, Dian

    2015-02-01

    Ongoing Himalayan growth is generally thought to be dominated by duplexing and/or extrusion processes. These models may be tested by reconstructing Himalayan fold-thrust belt growth since the middle Miocene. However, our knowledge of basic structural geometry remains too fragmentary to resolve the issue, even in areas with rich stratigraphic diversity such as the northwestern Indian Himalaya. In this region, a primary outstanding question involves the uncertain relationship of the Berinag thrust and the Tons thrust, structures with displacements of >80 km and >40 km, respectively. The uncertain geometry and kinematics allow for the complete range of duplexing or extrusion processes for the integrated kinematic history since the middle Miocene. To address this issue, field mapping and kinematic analysis were performed to reconstruct the deformation of the Lesser Himalayan Sequence in the northwest Indian Himalaya. Our results reveal a new discovery: a ~ 450 m thick top-to-southwest shear zone, termed the Pabbar thrust. The Pabbar thrust placed the Outer Lesser Himalayan Sequence (the Tons thrust hanging wall) directly on the Berinag Group (the Berinag thrust hanging wall). This discovery requires that the Berinag thrust and Tons thrust are, in fact, the same structure, and discrete duplexing processes dominated growth of the northwest Indian Himalaya for the past ~10-15 million years. Along-strike extension of these kinematics and corresponding geometries is consistent with the observed orogenic framework and resolves a stratigraphic continuity problem across the India-west Nepal border, where prior work suggests that structures are continuous but stratigraphy does not match.

  7. The role of gateways in the evolution of temperature and salinity of semi-enclosed basins: An oceanic box model for the Miocene Mediterranean Sea and Paratethys

    E-print Network

    Utrecht, Universiteit

    : An oceanic box model for the Miocene Mediterranean Sea and Paratethys M.P. Karami , A. de Leeuw, W. Krijgsman Paratethys Miocene Mediterranean Sea Marine gateways are important for semi-enclosed basins as they control), the Paratethys (of which at present only the Black Sea and Caspian Sea remain) and the Mediterranean Sea were

  8. Rocky Mountain Geology, v. 46, no. 1, p. 141, 16 figs., 7 tables, June 2011 1 Miocene basaltic magmatism in the Goldfield-Superstition volcanic

    E-print Network

    Liu, Paul

    Rocky Mountain Geology, v. 46, no. 1, p. 1­41, 16 figs., 7 tables, June 2011 1 Miocene basaltic Basaltic lavas form part of the Miocene (~20.5 to 18 Ma) Goldfield-Superstition silicic large igneous province in central Arizona. Most of the basalt erupted early in the development of this southern Basin

  9. Resin compounds from the seed cones of three fossil conifer species from the Miocene Clarkia flora, Emerald Creek, Idaho, USA, and from related extant species

    Microsoft Academic Search

    Angelika Otto; Bernd R. T. Simoneit; William C. Rember

    2003-01-01

    The terpenoid compositions of three conifer species from the Miocene Clarkia flora, Emerald Creek, Idaho, USA, and of related extant species were analyzed using gas chromatography-mass spectrometry. The extracts of the seed cones of Miocene Taxodium dubium, Glyptostrobus oregonensis, and Cunninghamia chaneyi (Cupressaceae s.l.) contain several sesqui- and diterpenoids which originate from the resins. Many of the terpenoids have been

  10. En echelon Miocene rifting in the southwestern United States and model for vertical-axis rotation in continental extension

    SciTech Connect

    Bartley, J.M. (Univ. of Utah, Salt Lake City (United States)); Glazner, A.F. (Univ. of North Carolina, Chapel Hill (United States))

    1991-12-01

    Two areas of intense early Miocene crustal extension in the southwestern United States, the Colorado River trough and the central Mojave Desert, are separated by a weakly deformed area in the eastern Mojave Desert. The authors propose that these areas form a left-stepping en echelon rift system linked by a ductile detachment at depth. The en echelon geometry explains the southward loss of displacement in the central Mojave Desert and northward loss of coeval displacement in the Colorado River trough, and it incorporates seismic reflection evidence that mid-crustal Tertiary extensional mylonites continue beneath the weakly deformed area. This geometry also explains clockwise paleomagnetic declination anomalies from lower Miocene rocks as recording thin-skinned, detached rotations; large-scale block rotations are not required. Obliquity of the northeast-trending crustal-extension vector to the east-west-trending early Miocene synextensional volcanic belt may have caused the en echelon pattern to develop.

  11. New constrains on the thermal history of the Miocene Jarando basin (Southern Serbia)

    NASA Astrophysics Data System (ADS)

    Andri?, Nevena; Životi?, Dragana; Fügenschuh, Bernhard; Cvetkovi?, Vladica

    2013-04-01

    The Jarando basin, located in the internal Dinarides, formed in the course of the Miocene extension affecting the whole Alpine-Carpathian-Dinaride system (Schmid et al., 2008). In the study area Miocene extension led to the formation of a core-complex in the Kopaonik area (Schefer et al., 2011) with the Jarando basin located in the hanging wall of the detachment fault. The Jarando basin is characterized by the presence of bituminous coals, whereas in the other intramontane basins in Serbia coalification did not exceed the subbituminous stage within the same stratigraphic level. Furthermore, the basin hosts boron mineralizations (borates and howlite) and a magnesite deposit, which again implies elevated temperatures. This thermal overprint is possibly due to post-magmatic activity related to the emplacement of Oligocene I-type Kopaonik and Miocene S-type Polumir granitoid (Schefer et al., 2011.). This research project is aimed at providing new information about the thermal history of the Jarando basin. Fifteen core samples from three boreholes and 10 samples from the surrounding outcrops were processed for apatite fission-track analysis. Additionally, vitrinite reflectance was measured for 11 core samples of shales from one borehole and 5 samples of coal from an underground mine. VR data of Early to Middle Miocene sediments reveal a strong post-depositional overprint. Values increase with the depth from 0.66-0.79% to 0.83-0.90%. Thus organic matter reached the bituminous stage and experienced temperatures of around 110-120?C (Barker and Pawlewicz, 1994). FT single grain ages for apatite scatter between 45 Ma to 10 Ma with a general trend towards younger ages with depth. Both, the spread in single grain ages together with the bimodal track lengths distribution clearly point to partial annealing of the detrital apatites. With the temperature given from the VR values the partial annealing points to a rather short-lived thermal event. This is assisted by thermal modelling of our fission track data indicating that maximum temperatures of <120°C around 15-12 Ma. We correlate the thermal event with the extension and core-complex formation followed by the syn-extensional intrusion of the Polumir granite. Later cooling from 10 Ma onwards is related to basin inversion and erosion.

  12. Miocene zircon crystals in dacite from Ilopango Caldera, El Salvador: Evidence for recycling of plutonic rocks

    NASA Astrophysics Data System (ADS)

    Garrison, J. M.; Korm, S.; Schmitt, A. K.; Economos, R. C.

    2011-12-01

    Ilopango Caldera is located in El Salvador and is part of the Central American Volcanic Arc (CAVA) that extends from southern Mexico to Panama. The volcanic arc is situated on crust that ranges in age from 150-28 Ma and is covered with Miocene-Recent volcanic ash and pyroclastic flow deposits. Several large eruptions are associated with Ilopango Caldera, the most recent are from the Tierra Blanca Joven (TBJ) eruption, which produced massive pyroclastic flows 1600 years BP. Older eruptions from Ilopango Caldera are referred to as the Tierra Blanca (TB) deposits, and the TB2 ignimbrite has been dated at 12,000 years. The objective of this research is to use the ages of zircon crystals from the TBJ and TB2 eruptions to establish and compare storage times for these magma reservoirs. We used a CAMECA ims 1270 at UCLA's NSF National Ion Microprobe Facility in order to obtain U-Pb and U-Th ages for individual zircon crystals from each eruption. Depth profiling and U-Pb analyses were performed on both of the zircon crystals using established analysis techniques. The data show that zircon from both eruptions have 15 Ma old cores with thin rims (few ?m) that are consistent with the young eruption ages. In both cases, however the transition from core to rim composition is abrupt and does not record continuous crystallization of the zircon crystals. We conclude that the presence of the old cores is consistent with assimilation of middle Miocene plutonic rock by juvenile magma during Quaternary activity of Ilopango Caldera. The most likely source of 15 Ma old zircon are the plutons associated with middle Miocene explosive volcanism in Central America. Ash deposits recovered from the sea floor (via ODP studies) record extensive explosive volcanism from 13-15 Ma that can be traced to ignimbrite deposits of the Chalatenango Formation in south-central Guatemala and El Salvador. We conclude that 1) the zircon crystals record only brief pre-eruptive crystallization histories for the TBJ and TB2 eruptions of Ilopango Caldera, 2) that the presence of nearly identical crystal ages in the TBJ and TB-2 rocks mean that the same plutonic source has been recycled since the early activity underneath Ilopango Caldera and 3) that the assimilant is likely the plutons related to the Miocene paleo-arc in El Salvador.

  13. Biostratigraphy and paleoenvironment of Miocene- Pliocene hemipelagic limestone: Kingshill Seaway, St. Croix, US Virgin Islands.

    USGS Publications Warehouse

    Lidz, B.H.

    1982-01-01

    The Kingshill Limestone and younger carbonate rocks constitute the central portion of St. Croix, forming the remains of an ancient seaway that was flanked by emergent highlands. The seaway has been filled with thick epipelagic sediments alternating with carbonate turbidites and ash falls and capped with shallow-water reefal and terrigenous debris. Planktonic foraminifera indicate that ages of these rocks range sequentially in a SW direction from the middle Miocene to lower Pliocene. Scanning electron micrographs illustrate 42 species and subspecies of pelagic foraminifera and 13 selected paleoenvironmentally significant aberrant forms.-from Author

  14. Aragonian stratigraphy reconsidered, and a re-evaluation of the middle Miocene mammal biochronology in Europe

    NASA Astrophysics Data System (ADS)

    Daams, R.; van der Meulen, A. J.; Alvarez Sierra, M. A.; Peláez-Campomanes, P.; Krijgsman, W.

    1999-02-01

    The recently collected fauna of Armantes 1A in Chron C5Br of the Armantes section necessitates reinterpretation of the previous bio- and magnetostratigraphical correlations between the Armantes and Vargas sections (Calatayud-Daroca Basin, Central Spain) [W. Krijgsman, M. Garcés, C.G. Langereis, R. Daams, J. van Dam, A.J. van der Meulen, J. Agust?´, L. Cabrera, A new chronology for the Middle to Late Miocene continental record in Spain, Earth Planet. Sci. Lett. 142 (1996) 367-380]. The long reversal in the Vargas section is now correlated to C5Br, instead of to C5Cr, on the basis of the biostratigraphical correlation of Armantes 1A to the faunas of Fuente Sierra 2 and 3 (in the Vargas section), which are situated in the basal part of the Middle Aragonian (MN5). This leads to the revised age of 16.0 Ma for the Early-Middle Aragonian (MN 4/5) boundary. Our age estimate of the MN5/6 boundary is maintained at ca. 13.75 Ma. The Vargas section is now considered to start in Chron C5Cn.2r and to end in C5Bn.1n. As a result of the revised correlation the duration of the time gap between the fossiliferous parts of Vargas and the younger Aragón section, previously estimated as ca. 1.5 Myr, is now reduced to less than 200,000 years. The tie points of the European mammal units (MN4-MN6) to the geomagnetic polarity time scale [F.F. Steininger, W.A. Berggren, D.V. Kent, R.L. Bernor, S. Sen, J. Agust?´, Circum-Mediterranean Neogene (Miocene and Pliocene) marine-continental chronologic correlations of European mammal units, in: R.L Bernor, V. Fahlbusch, H.-W. Mittmann (Eds.), The Evolution of Western Eurasian Neogene Mammal Faunas, Columbia Univ. Press, New York, 1996, pp. 7-46] are evaluated. Our age estimates of the MN4/5 and MN5/6 boundaries are compatible with the new magnetostratigraphic calibration of middle Miocene mammal zones in the Swiss Molasse basin [O. Kempf, T. Bolliger, D. Kälin, B. Engesser, A. Matter, New magnetostratigraphic calibration of Early to Middle Miocene mammal biozones of the North Alpine foreland basin, in: J.-P. Aguilar, S. Legendre, J. Michaux (Eds.), Actes du Congrès BiochroM '97, Mém. Trav. E.P.H.E. 21 (1997) 547-562].

  15. Miocene oceanographic changes of the western equatorial Atlantic (Ceara Rise) based on calcareous dinoflagellate cysts

    NASA Astrophysics Data System (ADS)

    Heinrich, Sonja; Zonneveld, Karin A. F.; Willems, Helmut

    2010-05-01

    The middle- and upper Miocene represent a time-interval of major changes in palaeoclimate leading to global cooling forming the precursor of the onset of Northern Hemisphere Glaciations (NHG). These climate changes are thought to be strongly controlled by oceanographic modifications although the nature of the relationship between ocean and climate change is far from clear. It has for instance been observed that in this time interval the modern deepwater circulation system; the thermohaline circulation was established. It is thought that tectonic events, such as the narrowing of the Panama gateway, played a key role in the progressing of these Miocene oceanographic changes (e.g. Duque-Caro 1990; Lear et al. 2003). However, the complex interaction between the closing of the Panama Gateway, the development of NADW, and thus the oceanographic progression towards our present day circulation is far from being fully understood. A key region to study these interactions is the Caribbean region, notably the Ceara Rise since it is an area of highest sensitivity to global deep water circulation changes. Here we intent to improve the understanding of these processes by establishing a detailed palaeoceanographic reconstruction of the western equatorial Atlantic Ocean on the basis of calcareous dinoflagellate cyst (dinocyst) associations. For this, we investigated sediment samples from ODP Site 926A by defining the calcareous dinocyst assemblage. Site 926A is located at the southwestern flank of the Ceara Rise, an area of highest sensitivity to global deep water circulation changes. At about 11 Ma, we see a distinct increase in the absolute abundances of the calcareous dinocysts suggesting enhanced productivity and better carbonate preservation that can be related to the intensification of NADW formation (Woodruff & Savin 1989). At 11.3 Ma, Leonella granifera, a species known to be strongly related to terrestrial input increases. This could be a signal for the initiation of the Amazon River as a transcontinental river (11.8 - 11.3 Ma; Figueiredo et al. 2009) in relation to Andean tectonism. References: Duque-Caro, H. (1990): Neogene stratigraphy, paleoceanography and palebiology in Northwest South America and the evolution of the Panama Seaway. Palaeogeography, Palaeoclimatology, Palaeoecology 77, 203-234. Figueiredo, J., Hoorn, C., van der Veen, P., Soares, E. (2009): Late Miocene onset of the Amazon River and the Amazon deep-sea fan: Evidence from the Foz do Amazonas Basin. Geology; v. 37, no. 7; p. 619 - 622. Lear, C.H., Rosenthal, Y., Wright, J.D. (2003): The closing of a seaway: ocean water masses and global climate change. Earth and Planetary Science Letters 210, 425-436. Woodruff, F., Savin, S.M. (1989): Miocene deepwater oceanography. Paloceanography 4, 87-140.

  16. Global climate and monsoons response to orbital forcing in the Late Miocene

    NASA Astrophysics Data System (ADS)

    Marzocchi, A.; Lunt, D. J.; Flecker, R.; Farnsworth, A.; Bradshaw, C.

    2014-12-01

    Global climate during the Late Miocene (11.61-5.33 Ma) is thought to have been generally warmer and wetter than at present day. The Northern Hemisphere was characterised by nearly ice-free conditions (with respect to the extent of the Greenland ice sheet) and some of the main marine gateways were undergoing opening or closure (e.g. Central American gateway, Bering Strait, and Indonesian Throughflow). Vegetation distribution was also generally more extensive than it is today, both at high and low latitudes. There is geological evidence of orbitally-forced cyclicity in sedimentary sections throughout the globe, especially in marginal basins such as the Mediterranean Sea. In the Late Miocene the entire North African catchment drained in the Eastern Mediterranean, constituting the main fresh water input into the basin, regulated by the North African monsoon. In addition, the Tibetan Plateau underwent substantial uplift throughout this time period, which strengthened the Asian monsoon system. The Late Miocene therefore represents an ideal scenario to investigate the impact of orbital forcing on the North African and Asian monsoon systems, the establishment of their teleconnections, and the associated vegetation changes. There still is considerable uncertainty in the reconstructed atmospheric CO2 levels for this time period, due to the patchy distribution (both spatially and temporally) of the available proxy record. Hence, we also explore the sensitivity of global climate to changing CO2 levels with different orbital configurations. We carried out a new series of 22 fully coupled atmosphere-ocean-vegetation numerical simulations, run at evenly spaced intervals (1kyr) through a full late Miocene precession cycle (~6.5 Ma), using a full-complexity general circulation model (HadCM3L). These model results show substantial changes to sea surface temperatures and regional atmospheric circulation on sub-precessional time scales. This triggers responses in the North African and Asian monsoon systems, which modify their timing, onset, intensity and seasonality. This has important consequences for vegetation distribution, with highly intensified precipitation patterns at times of minimum precession (maximum insolation) resulting in a greening of both the Sahel and Indian regions.

  17. Two flat-backed polydesmidan millipedes from the Miocene Chiapas-amber Lagerstätte, Mexico.

    PubMed

    Riquelme, Francisco; Hernández-Patricio, Miguel; Martínez-Dávalos, Arnulfo; Rodríguez-Villafuerte, Mercedes; Montejo-Cruz, Maira; Alvarado-Ortega, Jesús; Ruvalcaba-Sil, José L; Zúñiga-Mijangos, Luis

    2014-01-01

    Two species of fossil polydesmidan millipedes (Diplopoda: Polydesmida) embedded in amber are described from Miocene strata near Simojovel, in the Chiapas Highlands, Mexico. Maatidesmus paachtun gen. et sp. nov., placed into Chelodesmidae Cook, 1895, and Anbarrhacus adamantis gen. et sp. nov., assigned in the family Platyrhacidae Pocock, 1895. Morphological data from fossil specimens have been recovered using 3D X-ray micro-computed tomography and regular to infrared-reflected microscopy. Both fossil species are recognizable as new primarily but not exclusively, by collum margin modification and remarkable paranotal and metatergite dorsal sculpture. PMID:25162220

  18. Miocene marine shelf-bar and deltaic petroleum reservoirs of coastal Alabama and Mississippi/Alabama shelf

    SciTech Connect

    Mink, R.M.; Mancini, E.A.; Bearden, B.L.

    1989-03-01

    Middle and upper Miocene gas reservoirs found in coastal Alabama and the Mississippi/Alabama shelf are predominantly inner to middle neritic shelf-bar or deltaic sands. A Miocene delta system prograded from the west-northwest in offshore Louisiana-Mississippi into coastal Alabama and the Mississippi/Alabama shelf. Deltaic sedimentation primarily affected the western portion of the Mississippi/Alabama shelf, while neritic sedimentation predominated in the northeastern portion of the region in coastal Alabama. Basinal clays are prevalent in the southeastern portion of the Mississippi/Alabama shelf. The productive Miocene reservoir sands occur between depths of 1100 and 5100 ft and generally are from 10 to 200 ft thick. The quartz-rich sands range from fine to coarse grained and have subangular to rounded and moderately to well-sorted quartz grains. Reservoir porosity is primary intergranular and generally ranges from 21% to 35%, with permeabilities that may exceed 2000 md. The natural gas in these shallow reservoirs is primarily biogenic in origin. Productivity of the reservoirs is highly variable and is often characterized by high water saturation. Reservoir pressures, which generally range from 550 to 2300 psi, are also a major factor controlling productivity of these reservoirs. Middle Miocene reservoirs are most common in coastal Alabama, and upper Miocene reservoirs are most common in the Mississippi/Alabama shelf. Petroleum traps are principally sandstone porosity and permeability pinch-outs against regional dip with subtle closure and anticlinal nosing as secondary factors in many of the traps. These middle and upper Miocene gas sands are best delineated with relative amplitude seismic reflection data no which gas-charged sands are apparent as bright spots.

  19. Subtropical forest expansion in the middle Miocene Europe: pCO2, Antarctic ice volume and oceanic changes

    NASA Astrophysics Data System (ADS)

    Hamon, N.; Sepulchre, P.; Donnadieu, Y.; Ramstein, G.

    2012-04-01

    The middle Miocene is a crucial period for ape's evolution and corresponds to their appearance in Europe. The dispersion of apes was made possible by tectonic changes and the expansion of their habitat, which is tropical to subtropical forest, in Europe. The context in which the Middle Miocene Climatic Optimum occurred still lacks constraints in terms of atmospheric pCO2 and Antarctic ice sheet volume and extent. Using the coupled atmosphere - ocean GCM FOAM and the dynamic vegetation model CARAIB, we investigate the sensitivity of Miocene climate and vegetation to pCO2 levels and Antarctic ice sheet configurations. We performed sensitivity experiments to test the impact of varying pCO2 (280 ppmv, 560 ppmv and 700 ppmv) and Antarctic albedo (ice and tundra) on the European vegetation during the Middle Miocene Climatic Optimum. Our results indicate that higher than present pCO2 is necessary to simulate subtropical forest in Western and Central Europe during the middle Miocene. However, a threshold between 560 and 700 ppmv makes subtropical forest partly collapse, which is due to colder and slightly dryer conditions in Europe. This can be explained by the fact that CO2-induced warming of the high latitudes strongly reduces North Atlantic Deep Water formation, therefore reducing the heat transport in this region. Moreover, the albedo change over Antarctica, which is directly linked to the ice surface, leads to further warming in Europe, and the expansion of subtropical forest. These results suggest that a small East Antarctic Ice Sheet (25% of present-day ice volume) together with higher than present pCO2 are in better agreement with available European middle Miocene data.

  20. Cooling Mediterranean Sea surface temperatures during the Late Miocene provide a climate context for evolutionary transitions in Africa and Eurasia

    NASA Astrophysics Data System (ADS)

    Tzanova, Alexandrina; Herbert, Timothy D.; Peterson, Laura

    2015-06-01

    In the Late Miocene, grasslands proliferated, succulent plants diversified in the mid-latitudes, and the desert-like conditions appeared in the Sahara. Despite this major environmental change on land, the coeval deep-sea oxygen isotope record does not provide evidence for significant high latitude cooling or continental ice growth, making it difficult to relate widespread terrestrial environmental change to global climatic changes. A U 37 K? -derived sea surface temperature (SST) reconstruction spanning 13 to 6 Ma from uplifted hemipelagic sediments in Northern Italy provides the first continuous mid-latitude temperature record with which to compare the evolution of aridity and biotic events at similar latitudes in Northern Africa and Pakistan. Between 13 and 8.8 Ma, Mediterranean SST lay near the upper limit of the alkenone temperature proxy (?28 °C), exceeding modern SST at the site by as much as 10 °C. Throughout the record, sapropel layers correspond to local SST maxima, suggesting that Late Miocene hydrological conditions in the Mediterranean responded to insolation forcing via mechanisms similar to those documented for the Plio-Pleistocene. Mediterranean SST cooled rapidly beginning at ?8 Ma, with an episode of intense cooling to ?19 °C between 7.2 Ma and 6.6 Ma, followed by a rebound to ?25 °C preceding the Messinian Salinity Crisis at 5.9 Ma. These observations establish, for the first time, a direct relationship between increasing aridity in the Northern hemisphere mid-latitudes and significant cooling. Evidently, this cooling was not accompanied by significant growth in continental ice volume. The extreme warmth and subsequent cooling of the Mediterranean Sea are not well-represented in current Late Miocene climate models, which our results suggest underestimate regional warmth prior to the Late Miocene cooling. Evidence of secular cooling during the Late Miocene gives new support to the much-debated link between a possible decline in atmospheric CO2 levels and Late Miocene changes in vegetation on land.

  1. The incrementally zoned Miocene Ayagaures ignimbrite (Gran Canaria, Canary Islands)

    NASA Astrophysics Data System (ADS)

    Jutzeler, Martin; Schmincke, Hans-Ulrich; Sumita, Mari

    2010-09-01

    The 20-25 m thick trachyphonolitic Ayagaures ignimbrite cooling unit [(AY); 11.8 Ma] exposed over 250 km 2 (onshore volume ca. 4.5 km 3 DRE) is the uppermost and most voluminous cooling unit of the Middle Fataga Formation (MFF), part of the Fataga Group (ca. 13.3-ca. 9 Ma) on Gran Canaria (GC), Canary Islands (28°00' N, 15°35' W). Up to 19 flow units (named b-t) subdividing the AY have been identified throughout most of the area from proximally to the caldera wall to distally as far as 14 km away. Individual flow units were distinguished from each other and logged using mainly chemical criteria. Single and/or packages of flow units (A, B and C) are tentatively interpreted to correspond to compositionally distinct magma bodies erupted from the same magma reservoir. These source-controlled flow units are interpreted to reflect successive eruptive pulses during incremental subsidence of Tejeda caldera. We subdivided AY cooling unit into four welding facies. Tentative correlation with a major syn-ignimbrite turbidite drilled during ODP Leg 157 suggests a total DRE volume of > 50 km 3. The cooling unit as a whole becomes less evolved upwards as shown by major elements, trace elements and REE of bulk rock and phenocrysts. All phenocryst phases, dominantly sanidine-anorthoclase (up to 20 vol.%), with minor biotite, augite, titanite, haüyne and apatite, are unzoned and show an incremental compositional zoning in the stratigraphy. The shallow level parent magma reservoir is interpreted to have undergone strong mixing prior to starting its final compositional zoning in a thermodynamically equilibrated reservoir. Compositional zoning resulted in three main bodies. This compositional and physical layering may have been triggered by rapid growth of alkali feldspar and biotite throughout the erupted part of the magma chamber. Abundant titanite and haüyne phenocrysts in basal flow units and in a locally preserved, highly evolved fallout tephra are interpreted to reflect initial evacuation of a small volume, highly fractionated cupola. AY represents the most evolved part of a large, partially evacuated magma reservoir. Progressive downward tapping of the reservoir is interpreted to have been controlled by incremental caldera collapse. Absence of less evolved magmas suggests that the magma chamber was only partially evacuated. Incremental compositional zoning of the cooling unit, but unzoned phenocrysts and evacuation reversals show that mixing did not occur following initiation of alkali feldspar growth.

  2. Orbital forcing and climate response at the Oligocene-Miocene boundary: stable isotope records from IODP site U1334

    NASA Astrophysics Data System (ADS)

    Beddow, H.; Harrison, A.; Sluijs, A.; Wade, B.; Liebrand, D.; Lourens, L. J.

    2014-12-01

    An extreme, transient expansion of the Antarctic ice sheet at the Oligocene-Miocene boundary (the Mi-1 event) marks an important transition in Cenozoic climate. Here, we present new high-resolution benthic and planktic stable isotope records from IODP Site U1334, in the eastern equatorial Pacific Ocean. These newly generated records resolve the role of orbital forcing in late Oligocene - early Miocene climatic changes and reconstruct the evolution of surface to deep water gradients to improve our understanding of this pivotal boundary.

  3. Age and stratigraphic context of Pliopithecus and associated fauna from Miocene sedimentary strata at Damiao, Inner Mongolia, China

    NASA Astrophysics Data System (ADS)

    Kaakinen, Anu; Abdul Aziz, Hayfaa; Passey, Benjamin H.; Zhang, Zhaoqun; Liu, Liping; Salminen, Johanna; Wang, Lihua; Krijgsman, Wout; Fortelius, Mikael

    2015-03-01

    Since the discovery of mammalian fossils in Central Inner Mongolia in the beginning of the 20th century, this area has produced a rich and diverse record of Miocene faunas. Nevertheless, the stratigraphy has remained poorly constrained owing to scattered faunal horizons and lack of continuous vertical exposures. Consequently, most age estimates of these Miocene sites are based on paleontological evidence alone, with very few sites having been dated independently. Our field investigations in Damiao, in Siziwang Qi, Inner Mongolia have yielded more than 30 new fossiliferous localities from three horizons, including a pliopithecid fauna. This study presents the litho-, bio- and magnetostratigraphy of the Damiao area and provides age estimates for the three fossil-bearing horizons. The sedimentary sequence is interpreted as the remains of a fluvial system comprising channels, subaerially exposed floodplains and floodbasin environments. The two local stratigraphic sections measured and sampled for paleomagnetic analysis coincide with species-rich vertebrate fossil localities. The paleomagnetic results and faunal evidence suggest a correlation of lowermost fossil horizon (DM16) producing relatively rich small mammal assemblage to the early Miocene chron C6Ar or C6An.1r, roughly in 20-21 Ma age range. The pliopithecid locality level (DM01) represents latest middle Miocene and has an age estimate of about 12.1 Ma while the youngest localities (DM02) with cervoids and abundant and diverse small mammal fauna represents the earliest late Miocene with an age estimate of about 11.6 Ma. Our magnetostratigraphic results confirm that the Damiao strata constitute one of the best sequences in Inner Mongolia with early, middle and late Miocene mammalian faunas in stratigraphic superposition. The results also provide constraints on the paleoenvironmental evolution and bioevents of the area. The occurrence of pliopithecid primates in the middle Miocene of Inner Mongolia suggests humid habitats and challenges the scenarios suggesting arid and highly seasonal conditions for Central Asia since Early Miocene. The presence of pliopithecids may also bear witness to locally humid environments and greater habitat heterogeneity than previously known in central Inner Mongolia.

  4. Individual to community-level faunal responses to environmental change from a marine fossil record of Early Miocene global warming.

    PubMed

    Belanger, Christina L

    2012-01-01

    Modern climate change has a strong potential to shift earth systems and biological communities into novel states that have no present-day analog, leaving ecologists with no observational basis to predict the likely biotic effects. Fossil records contain long time-series of past environmental changes outside the range of modern observation, which are vital for predicting future ecological responses, and are capable of (a) providing detailed information on rates of ecological change, (b) illuminating the environmental drivers of those changes, and (c) recording the effects of environmental change on individual physiological rates. Outcrops of Early Miocene Newport Member of the Astoria Formation (Oregon) provide one such time series. This record of benthic foraminiferal and molluscan community change from continental shelf depths spans a past interval environmental change (? 20.3-16.7 mya) during which the region warmed 2.1-4.5°C, surface productivity and benthic organic carbon flux increased, and benthic oxygenation decreased, perhaps driven by intensified upwelling as on the modern Oregon coast. The Newport Member record shows that (a) ecological responses to natural environmental change can be abrupt, (b) productivity can be the primary driver of faunal change during global warming, (c) molluscs had a threshold response to productivity change while foraminifera changed gradually, and (d) changes in bivalve body size and growth rates parallel changes in taxonomic composition at the community level, indicating that, either directly or indirectly through some other biological parameter, the physiological tolerances of species do influence community change. Ecological studies in modern and fossil records that consider multiple ecological levels, environmental parameters, and taxonomic groups can provide critical information for predicting future ecological change and evaluating species vulnerability. PMID:22558424

  5. Local Group(s)

    E-print Network

    Eva K. Grebel

    2006-05-22

    The properties of the galaxies of the Local Group are reviewed, followed by a brief discussion of nearby groups. The galaxy groups in our vicinity - the M81 group, the Cen A group, and the IC 342/Maffei group - are in many respects Local Group analogs: Their luminosity functions, galaxy content, fractional galaxy type distribution, crossing times, masses, and zero-velocity surface radii are similar to those of the Local Group. Also, the nearby groups usually consist of two subgroups, some of which approach each other and may ultimately merge to form a fossil group. These poor groups contrast with the less evolved, loose and extended galaxy ``clouds'' such as the Scl group and the CVn I cloud. These are characterized by long crossing times, are dominated by gas-rich, late-type galaxies, and lack gas-deficient, low luminosity early-type dwarfs. These clouds may be groups still in formation. The local Hubble flow derived from the clouds and groups is very cold.

  6. Amazonian amphibian diversity is primarily derived from late Miocene Andean lineages.

    PubMed

    Santos, Juan C; Coloma, Luis A; Summers, Kyle; Caldwell, Janalee P; Ree, Richard; Cannatella, David C

    2009-03-10

    The Neotropics contains half of remaining rainforests and Earth's largest reservoir of amphibian biodiversity. However, determinants of Neotropical biodiversity (i.e., vicariance, dispersals, extinctions, and radiations) earlier than the Quaternary are largely unstudied. Using a novel method of ancestral area reconstruction and relaxed Bayesian clock analyses, we reconstructed the biogeography of the poison frog clade (Dendrobatidae). We rejected an Amazonian center-of-origin in favor of a complex connectivity model expanding over the Neotropics. We inferred 14 dispersals into and 18 out of Amazonia to adjacent regions; the Andes were the major source of dispersals into Amazonia. We found three episodes of lineage dispersal with two interleaved periods of vicariant events between South and Central America. During the late Miocene, Amazonian, and Central American-Chocoan lineages significantly increased their diversity compared to the Andean and Guianan-Venezuelan-Brazilian Shield counterparts. Significant percentage of dendrobatid diversity in Amazonia and Chocó resulted from repeated immigrations, with radiations at <10.0 million years ago (MYA), rather than in situ diversification. In contrast, the Andes, Venezuelan Highlands, and Guiana Shield have undergone extended in situ diversification at near constant rate since the Oligocene. The effects of Miocene paleogeographic events on Neotropical diversification dynamics provided the framework under which Quaternary patterns of endemism evolved. PMID:19278298

  7. Seal characterization for Miocene-age rocks of Texas Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Lu, J.; Meckel, T. A.; Treviño, R. H.

    2011-12-01

    The objective of the study is to characterize seal formations of Miocene age for geological storage of carbon dioxide in Gulf Coast of Mexico and to establish workflow for evaluation of sealing capacity. Two Miocene cores were studied as potential sealing units. Core samples of various lithologies, such as silty mudstone, siltstone, and fine-grained sandstones were analyzed using Mercury Intrusion Capillary Pressure (MICP), Scanning Electron Microscopy (SEM) on ion-milled samples, and high-resolution X-ray goniometry (HRXTG) analyses. The samples show varying sealing ability with capillary entry pressure ranging from 137 to 2146 psi. Sealing ability is controlled by several factors, such as grain sorting, abundance of clay and matrix, abundance of calcite cement, and clay alignment. Negative correlation between calcite abundance and porosity suggests that calcite cementation is an important porosity-reducing factor. The degree of alignment of clay fabrics shows a negative influence on porosity and permeability. SEM studies on ion-milled samples reveal that the majority of the pores are intragranular and are related to corrosion (several to hundreds of nanometers in size). Most pores are isolated within mineral grains and are not connected to an effective porosity network. The study demonstrates a series of effective methods for evaluation of sealing ability of geological formations.

  8. Long-term evolution of an Oligocene/Miocene maar lake from Otago, New Zealand

    NASA Astrophysics Data System (ADS)

    Fox, B. R. S.; Wartho, J.; Wilson, G. S.; Lee, D. E.; Nelson, F. E.; Kaulfuss, U.

    2015-01-01

    Maar is a highly resolved maar lake deposit from the South Island of New Zealand comprising laminated diatomite punctuated by numerous diatomaceous turbidites. Basaltic clasts found in debris flow deposits near the base of the cored sedimentary sequence yielded two new 40Ar/39Ar dates of 24.51 ± 0.24 and 23.38 ± 0.24 Ma (2?). The younger date agrees within error with a previously published 40Ar/39Ar date of 23.17 ± 0.19 Ma from a basaltic dyke adjacent to the maar crater. The diatomite is inferred to have been deposited over several tens of thousands of years in the latest Oligocene/earliest Miocene, and may have been coeval with the period of rapid glaciation and subsequent deglaciation of Antarctica known as the Mi-1 event. Sediment magnetic properties and SEM measurements indicate that the magnetic signal is dominated by pseudo-single domain pyrrhotite. The most likely source of detrital pyrrhotite is schist country rock fragments from the inferred tephra ring created by the phreatomagmatic eruption that formed the maar. Variations in magnetic mineral concentration indicate a decrease in erosional input throughout the depositional period, suggesting long-term (tens of thousands of years) environmental change in New Zealand in the latest Oligocene/earliest Miocene.

  9. CO2 drawdown following the middle Miocene expansion of the Antarctic Ice Sheet

    NASA Astrophysics Data System (ADS)

    Badger, Marcus P. S.; Lear, Caroline H.; Pancost, Richard D.; Foster, Gavin L.; Bailey, Trevor R.; Leng, Melanie J.; Abels, Hemmo A.

    2013-01-01

    The development of a permanent, stable ice sheet in East Antarctica happened during the middle Miocene, about 14 million years (Myr) ago. The middle Miocene therefore represents one of the distinct phases of rapid change in the transition from the "greenhouse" of the early Eocene to the "icehouse" of the present day. Carbonate carbon isotope records of the period immediately following the main stage of ice sheet development reveal a major perturbation in the carbon system, represented by the positive ?13C excursion known as carbon maximum 6 ("CM6"), which has traditionally been interpreted as reflecting increased burial of organic matter and atmospheric pCO2 drawdown. More recently, it has been suggested that the ?13C excursion records a negative feedback resulting from the reduction of silicate weathering and an increase in atmospheric pCO2. Here we present high-resolution multi-proxy (alkenone carbon and foraminiferal boron isotope) records of atmospheric carbon dioxide and sea surface temperature across CM6. Similar to previously published records spanning this interval, our records document a world of generally low (~300 ppm) atmospheric pCO2 at a time generally accepted to be much warmer than today. Crucially, they also reveal a pCO2 decrease with associated cooling, which demonstrates that the carbon burial hypothesis for CM6 is feasible and could have acted as a positive feedback on global cooling.

  10. Paleoenvironmental data as exploration tool in lower Miocene of offshore Texas

    SciTech Connect

    Carney, J.L.; Draper, L.P.; Gamber, J.H.; Geen, A.F.; Karmen, T.

    1985-02-01

    Most paleontological reports based on foraminiferal assemblages in well cuttings include an interpretation of the environment of deposition of the sediments penetrated. For an individual well, these data may be summarized as a paleoenvironmental maps and cross sections - useful tools for predicting sand distribution. These maps, used independently or in conjuction with net sand maps, can indicate the locations of ancient delta systems, hence sand sources. Paleoenvironmental cross sections graphically display transgressions and regressions. The lower Miocene sediments in the Mustang Island and Matagorda Island areas of offshore Texas were deposited in a wide range of shelf and upper slope paleoenvironments. Paleoenvironmental maps, based on about 50 wells, suggest that a number of major delta systems developed in the Mustang island and Matagorda Island areas during the early Miocene. Electric-log data show that thick pods of sand are associated with each of these ancient delta systems. Paleoenvironmental cross sections indicate that, although the section just above Siphonina davisi in southern Mustang Island is strongly regressive, the equivalent section in eastern Matagorda island is transgressive. Determination of such transgressive/regressive trends is vital to predicting the dip position of potential reservoir sands. A cross section through Matagorda block 622 illustrates that a considerable thickness of deep-water sediments can overlie an older, shallower water, sandy interval. Therefore, the penetration of a thick sequence of deep-water shales does not necessarily indicate that underlying prospective sections will not be encountered.

  11. Quality and petrographic characteristics of the lacustrine Ermenek coal (early Miocene), Turkey

    SciTech Connect

    Demirel, I.H.; Karayigit, A.I. [Hacettepe Univ., Beytepe-Ankara (Turkey). Dept. of Geological Engineering

    1999-05-01

    The early Miocene Yenimahalle Formation including alluvial-lacustrine sediments and a mineable coal steam with an average of 5 m in thickness rests unconformably upon the basement and is also unconformably overlain by marine limestones of the middle-late Miocene Mut Formation in the Ermenek coal basin. The coal basin in the present study has been subdivided into two areas, Canakci and Pamuklu-Tepebasi, which are separated by the basement and a fault, in order to determine coal properties in detail. The investigated subbituminous coals with an average of 0.40%Ro huminite reflectance often contain gastropod shells (Planorbidae) which commonly maintain the original aragonite and calcite composition. The coals have similar chemical properties and petrographic composition in the two areas, but their sulphur contents are clearly different. In the Canakci area the coals on an air-dried basis contain distinctly less total sulphur (avg. 1.3%) and organic sulphur contents (0.13--0.15%) than in the Pamuklu-Tepebasi area (avg. 4.5% and 4.25%, respectively). This difference is interpreted to be controlled by mire chemistry and sedimentation during peat formation.

  12. Paleoclimatic controls on sedimentation, diagnesis, and reservior quality: Lessons from Miocene carbonates

    SciTech Connect

    Sun, S.Q. (MASERA International, London (United Kingdom)); Esteban, M. (Moli d'en Moix, Palma de Mallorca (Spain))

    1994-04-01

    Miocene carbonates worldwide were deposited in a wide range of paleogeographic and tectonic settings and form important reservoirs in several regions. The reservoir quality of these carbonates appears to have been primarily controlled by the prevailing paleoclimate, which exerted a major control of both the depositional patterns and diagenetic pathways. Two end members are discussed here: (1) humid, oceanic tropical-subtropical settings, and (2) arid, land-locked temperate-subtropical settings. In humid, oceanic tropical-subtropical settings (e.g., Miocene of Southeast Asia), a warming trend paralleled by generally rising sea level allowed thick coral reefs and skeletal banks to develop, most of which are seismically resolvable. These carbonates typically represent several stages or cycles of development (largely third-order) separated by discontinuities in platform growth with episodic subaerial exposure. Development of economic reservoirs is mainly related to relative sea level falls and associated meteoric diagenesis. Trends and patterns of reservoir distribution can be predicted within a sequence stratigraphic framework. Basal transgressive carbonates are mostly tight because of their relatively fine-grained textures, intense compaction, and isolation from meteoric water influence. Best reservoir quality is commonly developed beneath subaerial unconformities in highstand buildups where effect of meteoric water leaching and karstification are most intense. 80 refs., 18 figs., 1 tab.

  13. Geological factors controlling gas volumes in Miocene carbonate buildups-offshore Sarawak

    SciTech Connect

    Smith, L.R. [Occidental international Exploration and Production Co., Bakersfield, CA (United States)

    1996-12-31

    Over 170 independent Miocene carbonate buildups are located within the Luconia Province of offshore Sarawak, Malaysia. They vary in size and shape from small isolated pinnacles through tabular to broad low relief platforms, distributed across nearly 10MM acres of the shallow Miocene shelf. Among the 70-odd buildups drilled to date, over half are gas-bearing. Discovered volumes exceeds 40 TCF of gas-in-place, with gas columns ranging from a few meters to greater than 500 m. Geological factors suspected of controlling the occurrence and volume of gas within each buildup include caprock, source, stratigraphic and structural variables. The source for gas is the (largely uncontrolled) Cycle I/II coastal plain sequence. In practice, only caprock and seismically-derived stratigraphic and structural factors provide sufficient geological/geophysical evidence to characterize and distinguish buildups at the prospect level. Useful caprock-related discriminators include clastictseismic facies, drape, and pore pressure - each reflecting the sealing capacity of the caprock as measured by the gas column height in the reservoir. Factors related to the gas-focusing effectiveness of bedding below the reservoir include the relief and structural configuration of the pre-carbonate section, the areal extent of the drainage area, and faulting. As prospect discriminators, these structural factors are limited by possible velocity distortions and poor seismic resolution beneath the carbonate section. Five gas accumulations discovered by Occidental since 1992 are compared to show the variety of discernible factors controlling their in-place volumes.

  14. Post-Miocene diagenetic and eustatic history of Enewetak Atoll: Model and data comparison

    SciTech Connect

    Quinn, T.M.; Matthews, R.K. (Brown Univ., Providence, RI (USA))

    1990-10-01

    The post-Miocene diagenetic and eustatic history of Enewetak Atoll was investigated using a one-dimensional forward model. Comparison of model and data suggests that the post-Miocene history of Enewetak Atoll was dominated by multiple episodes of meteoric phreatic diagenesis attendant with high-frequency (10{sup 4} to 10{sup 5} yr) fluctuations in sea level and a subsidence rate of 39.0 m/m.y. Sensitivity testing indicates that subaerial erosion results in the preservation of additional subaerial unconformities because stratigraphic shortening permits a succeeding sea-level rise to flood the exposure surface and deposit sediment, whereas without subaerial erosion this sea-level rise would be recorded as a paleophreatic lens. Model results indicate that less then 10% of lapsed time is recorded by sediment deposition during periods of high-frequency changes in sea level. Incompleteness of the stratigraphic record suggest that magnetostratigraphy may give erroneous ages for shallow-marine carbonate sequences deposited during times of high-frequency changes in sea level and frequent magnetic polarity reversals.

  15. New specimens of a fossil ostrich from the Miocene of Kenya

    NASA Astrophysics Data System (ADS)

    Leonard, Leona M.; Dyke, Gareth J.; Walker, Cyril A.

    2006-08-01

    Fossilised hind limb bones from the late Middle Miocene (approximately 14 million-year-old [MYA]) Fort Ternan, Kadianga West and Ngorora localities in Western Kenya indicate the presence of a new representative of the ostrich genus Struthio. These new fossils represent some of the oldest known records for Struthio yet described, slightly younger than Struthio coppensi, from the Lower Miocene of Namibia. Because the four sub-species of the modern-day ostrich ( Struthio camelus camelus, Struthio camelus australis, Struthio camelus massaicus, and Struthio camelus molybdophanes) inhabit the plains of Africa, and as recently as the 1940s, a fifth sub-species was also present in the Middle East and Saudi Arabia ( Struthio camelus syriacus), records of Struthio from Kenya and Namibia testify to the much wider distribution of these cursorial birds in the relatively recent past. This is further supported by the very high frequency of ostrich eggshell fragments found across Africa and Eurasia, which vastly outweighs the amount of skeletal material uncovered over the last century.

  16. Development of Miocene-Pliocene reef trend, St. Croix, U. S. Virgin Islands

    SciTech Connect

    Gill, I.; Eby, D.E.; Hubbard, D.K.; Frost, S.H.

    1988-01-01

    The Miocene-Pliocene reef trend on St. Croix, U.S. Virgin Islands, rims the present southern western coasts of the island and includes accompanying lagoonal and forereef facies. The reef trend was established on a foram-algal bank facies that represents basinal shallowing from the deep-water pelagic and hemipelagic facies of the Miocene Kingshill Limestone. Information on facies distribution and thickness is derived from rock exposures and 22 test wells drilled to a maximum depth of 91 m. The greatest thickness of the reef facies exists in a subsidiary graben on the south coast of St. Croix. The thickness of the reef section in this locality is due to preservation of the section in a downdropped block. Reef faunas include extant corals, as well as several extinct genera. Extant corals (e.g. Montastrea annularis, Diploria sp., and Porites porites) and extinct corals (e.g., Stylophora affinis, Antillea bilobata, and Thysanus sp.) are the main reef frame-builders. Coralline algea and large benthic foraminifera are significant contributors to the sediments both prior to and during scleractinian reef growth. Dolomitization and calcite cementation occur prominantly in an area corresponding to a Holocene lagoon. The spatial distribution of the dolomite suggests that the lagoon is a Tertiary feature directly related to the dolomitization process. Stable isotopic values suggest dolomitization of fluids of elevated salinity.

  17. Evidence for current-controlled sedimentation along the southern Mozambique continental margin since Early Miocene times

    NASA Astrophysics Data System (ADS)

    Preu, Benedict; Spieß, Volkhard; Schwenk, Tilmann; Schneider, Ralph

    2011-12-01

    Major plastered drift sequences were imaged using high-resolution multichannel seismics during R/V Meteor cruises M63/1 and M75/3 south of the Mozambique Channel along the continental margin of Mozambique off the Limpopo River. Detailed seismic-stratigraphic analyses enabled the reconstruction of the onset and development of the modern, discontinuous, eddy-dominated Mozambique Current. Major drift sequences can first be identified during the Early Miocene. Consistent with earlier findings, a progressive northward shift of the depocenter indicates that, on a geological timescale, a steady but variable Mozambique Current existed from this time onward. It can furthermore be shown that, during the Early/Middle Miocene, a coast-parallel current was established off the Limpopo River as part of a lee eddy system driven by the Mozambique Current. Modern sedimentation is controlled by the interplay between slope morphology and the lee eddy system, resulting in upwelling of Antarctic Intermediate Water. Drift accumulations at larger depths are related to the reworking of sediment by deep-reaching eddies that migrate southward, forming the Mozambique Current and eventually merging with the Agulhas Current.

  18. Migration of sharks into freshwater systems during the Miocene and implications for Alpine paleoelevation

    NASA Astrophysics Data System (ADS)

    Kocsis, László; Vennemann, Torsten W.; Fontignie, Denis

    2007-05-01

    Trace-element and isotopic compositions of fossilized shark teeth sampled from Miocene marine sediments of the north Alpine Molasse Basin, the Vienna Basin, and the Pannonian Basin generally show evidence of formation in a marine environment under conditions geochemically equivalent to the open ocean. In contrast, two of eight shark teeth from the Swiss Upper Marine Molasse locality of La Molière have extremely low ?18O values (10.3‰ and 11.3‰) and low 87Sr/86Sr ratios (0.707840 and 0.707812) compared to other teeth from this locality (21.1‰ 22.4‰ and 0.708421 0.708630). The rare earth element (REE) abundances and patterns from La Molière not only differ between dentine and enameloid of the same tooth, but also between different teeth, supporting variable conditions of diagenesis at this site. However, the REE patterns of enameloid from the “exotic” teeth analyzed for O and Sr isotopic compositions are similar to those of teeth that have O and Sr isotopic compositions typical of a marine setting at this site. Collectively, this suggests that the two “exotic” teeth were formed while the sharks frequented a freshwater environment with very low 18O-content and Sr isotopic composition controlled by Mesozoic calcareous rocks. This is consistent with a paleogeography of high-elevation (˜2300 m) Miocene Alps adjacent to a marginal sea.

  19. Rapid diversification of falcons (Aves: Falconidae) due to expansion of open habitats in the Late Miocene.

    PubMed

    Fuchs, Jérôme; Johnson, Jeff A; Mindell, David P

    2015-01-01

    Understanding how and why lineages diversify is central to understanding the origins of biological diversity. The avian family Falconidae (caracaras, forest-falcons, falcons) has an uneven distribution of species among multiple well-supported clades, and provides a useful system for testing hypotheses about diversification rate and correlation with environmental changes. We analyzed eight independent loci for 1-7 individuals from each of the 64 currently recognized Falconidae species, together with two fossil falconid temporal calibrations, to assess phylogeny, absolute divergence times and potential shifts in diversification rate. Our analyses supported similar diversification ages in the Early to Middle Miocene for the three traditional subfamilies, Herpetotherinae, Polyborinae and Falconinae. We estimated that divergences within the subfamily Falconinae began about 16mya and divergences within the most species-rich genus, Falco, including about 60% of all Falconidae species, began about 7.5mya. We found evidence for a significant increase in diversification rate at the basal phylogenetic node for the genus Falco, and the timing for this rate shift correlates generally with expansion of C4 grasslands beginning around the Miocene/Pliocene transition. Concomitantly, Falco lineages that are distributed primarily in grassland or savannah habitats, as opposed to woodlands, and exhibit migratory, as opposed to sedentary, behavior experienced a higher diversification rate. PMID:25256056

  20. Reorganization of Miocene deep water circulation in response to the shoaling of the Central American Seaway

    NASA Astrophysics Data System (ADS)

    Nisancioglu, Kerim H.; Raymo, Maureen E.; Stone, Peter H.

    2003-03-01

    The response of ocean circulation to the shoaling of the Central American Seaway (CAS) is investigated using the Massachusetts Institute of Technology (MIT) Ocean General Circulation Model (OGCM). In contrast to earlier model studies, it is found that significant amounts of deep water are formed in the North Atlantic prior to the closure of the CAS. However, the circulation pattern is fundamentally different from the modern ocean. In the upper layers of the CAS, there is a relatively strong geostrophic flow from the Pacific to the Atlantic, controlled by the pressure difference across the seaway. However, when the CAS is deeper than the level of North Atlantic Deep Water (NADW) outflow, a significant amount of NADW passes through the CAS to the Pacific Ocean. In the Pacific, the deep water traverses the basin from east to west in a relatively narrow zonal jet, and becomes a southward flowing western boundary current, before it joins with the Antarctic Circumpolar Current (ACC) to the south. This implies that deep sea sediment records from the Miocene Pacific Ocean could have been influenced by relatively young NADW and provides a new framework for the interpretation of geochemical tracer data. Diversification of benthic foraminifer fauna suggests that the CAS shoaled to a depth of about 1000 m toward the end of the middle Miocene. This would have prevented the passage of NADW to the Pacific and established the modern deep water circulation pattern at that time.