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1

Natural Arsenic in the Miocene Hawthorn Group, Florida: Wide Ranging Implications for ASR, Phosphate Mining, Private Well  

NASA Astrophysics Data System (ADS)

In order to understand the mineralogical association and distribution of arsenic (As) in the Hawthorn Group we examined in detail the chemical and mineralogical composition of 370 samples that were collected from 16 cores in central Florida. In our study area the Hawthorn group consists primarily of a basal carbonate unit (the Arcadia Formation) and an upper siliciclastic unit (The Peace River Formation). The Peace River Formation contains appreciable amounts of phosphate and is currently being exploited for phosphate ore. Samples were taken for each Formation at intervals of 25ft. In addition to the interval samples we also took samples that contained visible pyrite crystals, iron oxides, green clays, phosphatic and organic material. These additional samples were collected because of their potential of high As concentrations. Arsenic concentrations were determined by hydride generation - atomic fluorescence spectrometry (HG-AFS) after digestion with aqua regia (3:1 HCl and HNO3). The elements Fe, Na, Al, Si, Mg, Ca, S, P, and K were measured on the same solutions by inductively coupled plasma optical emission spectrometry (ICP-OES). The identification of discrete minerals was aided by scanning electron microscopy (SEM) and chemical compositions were obtained by electron-probe microanalyses (EMPA). Our study indicates that the average As concentrations significantly change from 9.0 ppm in the Peace River Formation to 3.0 ppm in the Tampa Member of the Arcadia Formation. As concentrations for all Hawthorn samples vary from 0.07 to 68.98 ppm ( ? = 5.6, ? = 7.1). Our detailed mineralogical and geochemical study demonstrates that: (1) The As in the Hawthorn group varies from the formation to formation and is mostly concentrated in trace minerals, such as pyrite; (2) Concentrations of the As in pyrite crystals can vary drastically from a minimum of 0 ppm to a maximum of 8260 ppm; (3) Pyrite is an unevenly distributed throughout the Hawthorn Group; (4) Phosphate and organic material, clays, and iron oxides contain lower As concentrations contrasted to pyrite; (5) Pyrite occurs in framboidal and euhedral forms. Because phosphorous, arsenic and sulfur are chemically closely related, they often occur together in nature, thus posing a potential problem for the phosphate industry. There have been several occurrences of swine fatalities due to arsenic poisoning as a result of phosphate feed supplements. Information about the concentration, distribution and mineralogical association of naturally occurring As is important, because this is a first step to forecast its behavior during anthropogenic induced physico-chemical changes in the aquifer. Recently, aquifer storage and recovery (ASR) facilities in central Florida reported As concentrations in excess of 100 ? g/L in recovered water. The ASR storage zone is the Suwannee Limestone, which directly underlies the Hawthorn sediments. It is crucial to the future of ASR in this area to understand the source and distribution of arsenic in the overlying Hawthorn Group and the cycling of arsenic in the Florida platform.

Lazareva, O. V.; Pichler, T.

2004-12-01

2

Hawthorn  

MedlinePLUS

... and kidney problems. More recently, hawthorn leaf and flower have been used as folk or traditional remedies ... disease (such as angina). The hawthorn leaf and flower are used to make liquid extracts, usually with ...

3

Hawthorn.  

PubMed

Crataegus monogyna Jacq (Lindm), C. laevigata (Poir) DC, or related Crataegus species, collectively known as hawthorn, have been used in the treatment of cardiovascular diseases. Clinical studies have found that standardized extracts show promise as adjunctive agents for the treatment of left ventricular dysfunction. Other trials consistently demonstrate its ability to improve exercise tolerance and symptoms of mild to moderate heart failure. Preliminary evidence indicates that it improves left ventricular performance, as measured by ejection fraction. In order to properly use hawthorn in the treatment of heart failure, a large, controlled, multicenter trial in which mortality serves as the primary endpoint is needed. PMID:12597258

Fong, Harry H S; Bauman, Jerry L

2002-07-01

4

Origin of dolomite in the phosphatic Hawthorne Group of Florida  

SciTech Connect

In addition to large amounts of phosphorite, the Miocene Hawthorn Group of Florida contains abundant dolomite. Dolomite is present as disseminated silt-size rhombs, as friable dolosilt beds, and as pore-filling cement in dolostone beds and clasts. The dolomite formed during early burial diagenesis both in the sulfate-reduction zone, overlapping and extending below sediment depths of phosphorite formation, and in adjacent, nonphosphatic, shallow-water lagoonal environments. Much of the dolomite is closely associated with the fibrous, Mg-rich clay minerals palygorskite and sepiolite. The percent carbonate in the Hawthorn Group increases from north to south; the dominant carbonate mineral in north Florida is dolomite, whereas dolomite and calcite are both abundant in south Florida. The [delta][sup 13]C values of the dolomite, from +1.82 to [minus]6.21[per thousand] PDB, suggest that metastable biogenic carbonate (aragonite and high-Mg calcite) and seawater were the predominant sources of carbonate. However, negative [delta][sup 13]C values of dolomite from northeast Florida suggest that as much as 30--40% of the carbonate was derived from degradation of organic matter. Degradation of organic matter enhanced dolomitization by removing sulfate ion and increasing the carbonate alkalinity of the pore waters. The oxygen and strontium isotopic values along with moderate Na contents indicate a marine origin. Evaporation of seawater or mixing of seawater and meteoric water were apparently not major factors in dolomite formation. The presence of dolomite, along with phosphorite, in reworked sequences can indicate deposition of organic-rich sediments from which most of the organic matter has since been removed.

Compton, J.S.; Hall, D.L.; Mallinson, D.J. (Univ. of South Florida, St. Petersburg, FL (United States). Dept. of Marine Science); Hodell, D.A. (Univ. of Florida, Gainesville, FL (United States). Dept. of Geology)

1994-07-01

5

Work Groups: From the Hawthorne Studies to Work Teams of the 1990s and Beyond  

Microsoft Academic Search

This article summarizes the Hawthorne studies related to work groups and their legacy and traces applications of work groups and related empirical research through the 1990s. A selective review of empirical studies of work group effectiveness conducted in work settings and published in the last 20 years addresses 4 questions: (a) What identifying features have field researchers used in operationally

Eric Sundstrom; Michael McIntyre; Terry Halfhill; Heather Richards

2000-01-01

6

The Phyllomedusa perinesos group (Anura: Hylidae) is derived from a Miocene Amazonian Lineage.  

PubMed

The Phyllomedusa perinesos group is composed of four species that inhabit cloud forests in the eastern Andean slopes. We estimated the phylogenetic relationships among them and their closest relatives using mitochondrial DNA sequences. Our results confirm the monophyly of the group and a close relationship with the Amazonian species Phyllomedusa atelopoides and Phyllomedusa tomopterna. A chronogram indicates that the group originated during the Miocene and the contemporary species diverged from their closest relatives during the Miocene and early Pliocene. The timing of the group's origin suggests that its evolution was linked to the rise of the eastern Andes. Based on the phylogeny we expand the species content of the group to include P. atelopoides and P. tomopterna. PMID:25112990

Ron, Santiago R; Almendariz, Ana; Cannatella, David C

2013-01-01

7

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.

8

Nathaniel Hawthorne Bicentennial Exhibition  

NSDL National Science Digital Library

Rightly regarded as one of the great figures of American letters, Nathaniel Hawthorne is best known for such works as The House of the Seven Gables, and of course one of America's oft-cited morality tales, The Scarlet Letter. He was part of a wide circle of other notable figures in 19th-century American literature that included Henry David Thoreau, Herman Melville, and Henry Wadsworth Longfellow. Given his strong connection with New England and his birth in Salem, Massachusetts, it is not surprising that the acclaimed Peabody Museum in that same town has mounted a significant exhibit to commemorate the bicentennial of Hawthorne's birth in 1804. For those who cannot make it to Salem in the coming months, this online exhibit is a true delight. The site includes the complete digitized images of "The Spectator", which was a hand-copied newspaper produced by Hawthorne when he was 16. Clearly, those with a penchant for learning about the life of Hawthorne will want to make several trips to this site.

9

Diagenetic history of the Surma Group sandstones (Miocene) in the Surma Basin, Bangladesh  

NASA Astrophysics Data System (ADS)

This study examines the various diagenetic controls of the Miocene Surma Group sandstones encountered in petroleum exploration wells from the Surma Basin, which is situated in the northeastern part of the Bengal Basin, Bangladesh. The principal diagenetic minerals/cements in the Surma Group sandstones are Fe-carbonates (with Fe-calcite dominating), quartz overgrowths and authigenic clays (predominantly chlorite, illite-smectite and minor kaolin). The isotopic composition of the carbonate cement revealed a narrow range of ? 18O values (-10.3‰ to -12.4‰) and a wide range of ? 13C value (+1.4‰ to -23.1‰). The ? 13C VPDB and ? 18O VPDB values of the carbonate cements reveal that carbon was most likely derived from the thermal maturation of organic matter during burial, as well as from the dissolution of isolated carbonate clasts and precipitated from mixed marine-meteoric pore waters. The relationship between the intergranular volume (IGV) versus cement volume indicates that compaction played a more significant role than cementation in destroying the primary porosity. However, cementation also played a major role in drastically reducing porosity and permeability in sandstones with poikilotopic, pore-filling blocky cements formed in early to intermediate and deep burial areas. In addition to Fe-carbonate cements, various clay minerals including illite-smectite and chlorite occur as pore-filling and pore-lining authigenic phases. Significant secondary porosity has been generated at depths from 2500 m to 4728 m. The best reservoir rocks found at depths of 2500-3300 m are well sorted, relatively coarse grained; more loosely packed and better rounded sandstones having good porosities (20-30%) and high permeabilities (12-6000 mD). These good quality reservoir rocks are, however, not uniformly distributed and can be considered to be compartmentalized as a result of interbedding with sandstone layers of low to moderate porosities, low permeabilities owing to poor sorting and extensive compaction and cementation.

Rahman, M. Julleh Jalalur; McCann, Tom

2012-02-01

10

Sedimentology of the Navosa Group (Miocene-Pliocene), SW Viti Levu, Fiji (South Pacific)  

SciTech Connect

The Navosa Group consists of the Vunamaoli Conglomerate, newly defined Sovi Sandstone, and Tamanua Formation. The first two units are lateral-facies equivalents in a coarse-grained, volcaniclastic, slope apron-submarine fan depositional system. These marine rocks are restricted to a narrow, linear fault-bounded basin in southwest Viti Levu that opened and then deformed in an episode of late Miocene transform tectonics. The marine rocks are unconformably( ) overlain by the nonmarine, early Pliocene Tamanua Formation. Slope-apron deposits in the Vunamaoli Conglomerate consist of thick, laterally discontinuous, massive boulder diamictites, basement blocks, and slumps along the southern margin of the basin. The diamictites are interpreted as high-density gravelly mass-flow deposits resulting from basin-margin faulting. Along the basin edge these are interspersed with proximal submarine fan deposits. Inner fan regions contain prograding, lenticular, conglomeratic fan lobs composed of cobble-boulder diamictite, normal to inversely graded pebble-cobble conglomerate, pebbly mudstone, and coherent slump blocks with adjacent levee deposit and interdistributary channel thin-bedded turbidites. Mid-fan regions are composed of sheet-like to broadly lenticular high- and low-density sandy turbidites. Outer fan regions consist of poorly exposed, sheet-like, low-density sandy turbidites, and pelagic deposits. The Tamanua Formation represents deposits from north-flowing, gravel-bed load streams and colluvium. Recognizable features include channels, cutbanks, scours, cluster bed forms, cross-bedded gravels, intraclasts, overbank deposits, and paleosols. Paleocurrent and provenance data from the Tamanua Formation suggest there was little topographic relief across the faults that influenced earlier marine deposition.

Evans, J.E. (Bowling Green State Univ., OH (USA))

1990-05-01

11

Lower miocene larger foraminifera and petroleum potential of the Tai Formation, Mergui Group, Andaman Sea  

NASA Astrophysics Data System (ADS)

Tertiary larger foraminifera are recorded for the first time from Thailand. The fauna studied is restricted mainly to the reefal carbonate of the Tai Formation, which rests unconformably on the pre-Late Eocene quartz-chlorite schist basement in the Central High region of the Mergui Basin. The formation is broadly correlatable with the Peutu Formation of the North Sumatra Basin. The Tai Formation can be divided into three units at the type locality; a basal unit of interbedded anhydrite, dolomite, shale and sandstone; a middle unit of coral/algal reefal limestones, and an upper unit of calcarenites interbedded with silty shales and sandstones. The middle and upper units have yielded a fauna comprising; Lepidocyclina (Nephrolepidina) japonica, Spiroclypeus yabeii, Cycloclypeus eidae, Cycloclypeus sp. A, Heterostegina sp. A, Lepidocyclina (N) sp. A, Miogypsina sp. A, and Miogypsinoides sp. L. (N) japonica and Miogypsinoides sp. can range up into the Middle Miocene (Lower Tf) whilst C. eidae can range down into the Upper Oligocene (Lower Te). The fauna is typical of the Indo-West Pacific Miocene faunal province of Adams (1970) and shows closer affinities to the faunas of Indonesia than those of India-Pakistan.

Polachan, Songpope; Racey, Andrew

12

Hawthorne's Dating Problem in The Scarlet Letter  

Microsoft Academic Search

This article explores the dating problem in Nathaniel Hawthorne's novel, The Scarlet Letter. In The Custom House, Hawthorne relates how he discovers several foolscap sheets written by a predecessor, Mr. Surveyor Pue, about Hester Prynne. These six sheets supposedly offer two types of accounts about Hester: aged persons, alive in the time of Pue and from whose oral testimony he

Hal Blythe; Charlie Sweet

2003-01-01

13

Genetic relationships among some hawthorn (Crataegus spp.) species and genotypes.  

PubMed

The genus Crataegus is well distributed in Turkey as a wild plant, with numerous, inherently variable species and genotypes. RAPD markers were used to study 17 hawthorn genotypes belonging to Crataegus monogyna ssp. monogyna Jacq (2 genotypes), C. monogyna ssp. azarella Jacq (1), Crataegus pontica K.Koch (3), Crataegus orientalis var. orientalis Pallas Ex Bieb (3), Crataegus pseudoheterophylla Pojark (1), Crataegus aronia var. dentata Browicz (1), C. aronia var. aronia Browicz (4), and Crateagus x bornmuelleri Zabel (2). The 10 RAPD primers produced 72 polymorphic bands (88% polymorphism). A dendrogram based on Jaccard's index included four major groups and one outgroup according to taxa. The lowest genetic variability was observed within C. aronia var. aronia genotypes. The study demonstrated that RAPD analysis is efficient for genotyping wild-grown hawthorns. PMID:20640884

Yilmaz, Kadir Ugurtan; Yanar, Makbule; Ercisli, Sezai; Sahiner, Hatice; Taskin, Tuncer; Zengin, Yasar

2010-10-01

14

Pomological Characteristics of Hawthorns Species Found in Van Region  

Microsoft Academic Search

Hawthorns have not gained adequate importance in both Turkey and the World yet. This study aimed to determine the hawthorn species of the region of Van in Turkey to analyze fruit characteristics. Ninety eight hawthorn genotypes were determined by pre- selection in Geva? and Edremit towns of Van. However, fruit samples were only 31 types from Geva? and 18 types

Ahmet KAZANKAYA

15

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

ERIC Educational Resources Information Center

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)

Harshbarger, Scott

1994-01-01

16

Correlation and analysis of Miocene paleochannels in the central Sierra Nevada, California, as displayed by the Stanislaus Group  

NASA Astrophysics Data System (ADS)

The proposed Neogene uplift of the Sierra Nevada has been debated for several decades. Although multiple lines of evidence indicate substantial uplift of the Sierran crest over the last ten million years, recent isotopic and paleobotanical methods have called the validity of these calculations into question. Our study focuses on the discontinuous units of the Miocene Stanislaus Group: Table Mountain Formation lavas, Dardenelles Formation lavas, and Eureka Valley Tuff (EVT) lava and tuffs. These units are significant because they have been used as a tilt indicator to calculate the uplift of the Sierra Nevada crest since their emplacement, 9.0-10.2 million years ago. Our research increased the quantity of primary data, which will be used to develop and verify a digitally-derived model of the paleodrainage systems of the ancient Sierra Nevada. The localities, Dorrington, Pikes Peak, Rancheria Mountain, Three Chimneys, and Sonora Pass are significant because they may represent the few remaining Table Mountain Formation (trachyandesite) outcrops of previously unmapped paleodrainage channels. To test this hypothesis, geochemical and paleomagnetic data were used to correlate the localities and thereby reconstruct the paleochannels. Outcrops near Dorrington, California contain biotite, display eutaxitic textures and are characterized by a reverse polarity indistinguishable from the Tollhouse Flat Member of the EVT. Previously mapped as Table Mountain Latite, we reclassify these units as Tollhouse Flat Member and eliminate the hypothesis that the units were once part of a potentially lava-back-flooded tributary of the paleo-Stanislaus River. The high potassium, columnar jointed lava at Pikes Peak, exhibits normal polarity; it is plausibly part of the Stanislaus Group and may be correlated to flows along the main 'cataract channel' of the Stanislaus Group. Results from Rancheria Mountain verify the presence of Stanislaus Group lavas and the EVT, previously mapped by Huber et al. (1989). The normal polarity trachyandesite lavas, which have a limited distribution, may be locally sourced; the reversed polarity lavas correlate to outcrops near the Stanislaus Group source area at Little Walker Caldera. Mapping near Three Chimneys confirms the presence of the EVT and a capping trachyandesite lava previously mapped by Huber (1983). We show that the capping lava is younger than the EVT and thus cannot be Table Mountain Formation, as attributed by Huber (1983). This high potassium normal-polarity lava could be part of the Lava Flow Member of the EVT or the Dardanelles Formation. Lastly, Ar/Ar geochronology on the reversed polarity lava of the 'Table Mountain Event' geomagnetic excursion within the Table Mountain Formation suggests that the dated lava erupted during the subchron C5n.2n-1, the first known direct dating of volcanic rocks of this subchron.

Jones, S.; Pluhar, C. J.; Farner, M. J.; Deino, A. L.

2013-12-01

17

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

Microsoft Academic Search

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

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

2006-01-01

18

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

Microsoft Academic Search

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

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

2008-01-01

19

HAWTHORNE, THE HIPPIE, AND THE SQUARE  

Microsoft Academic Search

Thought and feeling associated with the hippies is not new. Our hippies are heirs to a tradition entering America with the Pilgrims and Puritans, present since in varying combinations and emphases, and reflected continuously in our literature. Hawthorne particularly shared hippie aversions and aspirations. All his work, but especially The House of the Seven Gables and \\

EARL HILTON

1970-01-01

20

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

PubMed

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 the relative amounts of each differed between species. Raspberry flower wax also contained fatty acid methyl esters, a group of compounds that has rarely been detected in plant epicuticular waxes, however, these were not observed in hawthorn flower wax. Long-chain alcohol-fatty acid esters with carbon numbers ranging from C36 to C48 were also detected in both plant species. However, an examination of their constituent acids indicated that in hawthorn the esters based on the C16 fatty acid predominated, whilst in raspberry flower wax, esters based on the C20 fatty acid were most abundant. Both species also contained pentacyclic triterpenoids, which accounted for, on average, over 16 and 48% of the total wax extracted from raspberry and hawthorn flowers respectively. In the former, ursolic and oleanolic acids accounted for over 90% of the pentacyclic triterpenes, whilst hawthorn flower wax, in addition to containing these acids, also contained high relative concentrations of both free and esterified alpha- and beta-amyrins. PMID:11065285

Griffiths, D W; Robertson, G W; Shepherd, T; Birch, A N; Gordon, S C; Woodford, J A

2000-09-01

21

The Miocene rodents of Serbia  

Microsoft Academic Search

During the Miocene period a group of shallow lakes was created in depressions at the territory of present-day Serbia. This caused the present wide distribution of lacustrine sediments, which occasionally alternate with the alluvial and marsh sediments. The remains of large mammals are relatively common, while the remains of small mammals used to be known only from two localities -

Z. Markovic

2009-01-01

22

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)

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.

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

2007-11-01

23

Geographical parthenogenesis in Pacific Northwest hawthorns (Crataegus; Rosaceae)  

E-print Network

lato and the morphologically distinct Crataegus suksdorfii complex that comprises diploidsARTICLE Geographical parthenogenesis in Pacific Northwest hawthorns (Crataegus; Rosaceae) E.Y.Y. Lo in Crataegus series Douglasianae, an agamic complex comprising exclusively tetraploid Crataegus douglasii sensu

24

Secular variation of the middle and late Miocene geomagnetic field recorded by the Columbia River Basalt Group in Oregon, Idaho and Washington, USA  

NASA Astrophysics Data System (ADS)

This study of 118 discrete volcanic flows from the Columbia River Basalt Group is aimed to determine their distribution of geomagnetic field directions and virtual geomagnetic poles (VGPs) and to compare the inherent secular variation parameters with those from other studies. The magnetic signature of these rocks is uniformly carried by primary titanomagnetite, indicating that magnetic changes are due to variations in the magnetic field. Although most flows are flat lying, those that are tilted pass the Tauxe and Watson tilt test. Sequential flows with statistically similar site means were grouped, and directions that were considered outliers were evaluated and removed using the Vandamme cut-off method. Three normal-polarity (N-polarity) and three reversed-polarity (R-polarity) intervals are revealed by the stratigraphically ordered flows and have mean directions of N polarity (dec/inc = 6.6°/+61.2°, k = 29.3, ?95 = 4.2°), and R polarity (dec/inc = 178.2°/-59.2°, k = 16, ?95 = 5.5°). Regression analysis indicates that the secular variation analysis has not been affected by regional rotation, and that apparent polar wander is negligible. The VGP distribution is almost perfectly circular and supports the preference of VGP positions for the dispersion analysis. Dispersion parameters with corrections for within-site scatter (Sb) show a range of 14.3°-25.5°, including error limits, and were consistently higher for R-polarity results than for those of N polarity. Published dispersion parameters for extrusives <5 Ma show Sb values slightly lower than ours, yielding values of 16°-19°, although the difference is not statistically significant. In contrast, published dispersion parameters from high quality data from the Cretaceous Normal Superchron are lower than those for the Neogene, which suggests that the noisiness of the magnetic field correlates with the frequency of reversals. Our new results allow us to extend the Plio-Pleistocene palaeosecular variation database to the bottom of the middle Miocene. Many Miocene formations on a variety of continents are suitable targets for future analysis. Furthermore, the significant difference between the reversed and N-polarity dispersion parameters is intriguing and needs substantiation.

Dominguez, Ada R.; Van der Voo, Rob

2014-06-01

25

Hawthorn (Crataegus spp.) in the treatment of cardiovascular disease  

PubMed Central

The medicinal properties of hawthorn (Crataegus spp., a genus comprising approximately 300 species) have been utilized by many cultures for a variety of therapeutic purposes for many centuries. In the Western world cardiovascular disease (CVD) has become one of the single most significant causes of premature death. Echoing this situation, more recent research into the therapeutic benefits of hawthorn preparations has focused primarily upon its cardiovascular effects. This review covers research into the various mechanisms of action proposed for Crataegus preparations, clinical trials involving Crataegus preparations, and the herb's safety profile. Clinical trials reviewed have been inconsistent in terms of criteria used (sample size, preparation, dosage, etc) but have been largely consistent with regard to positive outcomes. An investigation into data available to date regarding hawthorn preparations and herb/drug interactions reveals that theoretical adverse interactions have not been experienced in practice. Further, adverse reactions relating to the use of hawthorn preparations are infrequent and mild, even at higher dosage ranges. A recent retrospective study by Zick et al. has suggested a negative outcome for the long-term use of hawthorn in the prognosis of heart failure. These findings are examined in this paper. Although further research is needed in certain areas, current research to date suggests that hawthorn may potentially represent a safe, effective, nontoxic agent in the treatment of CVD and ischemic heart disease (IHD). PMID:22228939

Tassell, Mary C.; Kingston, Rosari; Gilroy, Deirdre; Lehane, Mary; Furey, Ambrose

2010-01-01

26

Hawthorn (Crataegus monogyna Jacq.) extract exhibits atropine-sensitive activity in a cultured cardiomyocyte assay.  

PubMed

Hawthorn (Crataegus spp.) plant extract is used as a herbal alternative medicine for the prevention and treatment of various cardiovascular diseases. Recently, it was shown that hawthorn extract preparations caused negative chronotropic effects in a cultured neonatal murine cardiomyocyte assay, independent of beta-adrenergic receptor blockade. The aim of this study was to further characterize the effect of hawthorn extract to decrease the contraction rate of cultured cardiomyocytes. To test the hypothesis that hawthorn is acting via muscarinic receptors, the effect of hawthorn extract on atrial versus ventricular cardiomyocytes in culture was evaluated. As would be expected for activation of muscarinic receptors, hawthorn extract had a greater effect in atrial cells. Atrial and/or ventricular cardiomyocytes were then treated with hawthorn extract in the presence of atropine or himbacine. Changes in the contraction rate of cultured cardiomyocytes revealed that both muscarinic antagonists significantly attenuated the negative chronotropic activity of hawthorn extract. Using quinuclidinyl benzilate, L-[benzylic-4,4'-(3)H] ([(3)H]-QNB) as a radioligand antagonist, the effect of a partially purified hawthorn extract fraction to inhibit muscarinic receptor binding was quantified. Hawthorn extract fraction 3 dose-dependently inhibited [(3)H]-QNB binding to mouse heart membranes. Taken together, these findings suggest that decreased contraction frequency by hawthorn extracts in neonatal murine cardiomyocytes may be mediated via muscarinic receptor activation. PMID:18696181

Salehi, Satin; Long, Shannon R; Proteau, Philip J; Filtz, Theresa M

2009-01-01

27

Yields of hawthorn Crataegus monogyna berries under different hedgerow management  

Microsoft Academic Search

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

T. H Sparks; T Martin

1999-01-01

28

Nathaniel Hawthorne and Herman Melville: A Research Guide.  

ERIC Educational Resources Information Center

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…

Van Noate, Judith, Comp.

29

Is the Hawthorne Effect in Educational Experiments a Chimera?  

ERIC Educational Resources Information Center

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…

Bauernfeind, Robert H.; Olson, Carl J.

1973-01-01

30

UBC Museum of Anthropology Audrey & Harry Hawthorn Library & Archives  

E-print Network

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

Strynadka, Natalie

31

Fourth Period Discovers Hester as Mother: Hawthorne's Mother?  

ERIC Educational Resources Information Center

A teacher discusses how she used criticism of "The Scarlet Letter," when studying the book, in her honors class. The students were also intrigued by the biographical information they learned about Hawthorne, and eager to use it in interpreting his novel. (SRT)

Heginbotham, Eleanor

1986-01-01

32

The Persistence of Theocracy: Hawthorne's The Scarlet Letter  

Microsoft Academic Search

This article argues that Nathaniel Hawthorne's The Scarlet Letter can provide insight into the persistent appeal of the moral and political certitudes that theocracy offers and that can serve as a corrective to liberal secularism's often myopic tendency to downplay the continuing moral and political appeal of religious belief and authority. Focusing on three puzzles raised in the structure and

Constance C. T. Hunt

2009-01-01

33

Community Recreation Center greenhouse solar collector, Hawthorne, Nevada. Final report  

SciTech Connect

A solar collector greenhouse and a trombe wall are proposed for the south wall of the Community Recreation Center, Hawthorne, Nevada. The project was integrated with retrofit of an old gymnasium that is still in progress. Thermometers are being used to monitor temperatures inside the greenhouse, inside the gymnasium, and in the outdoors. (BCS)

Not Available

1981-04-01

34

Immunomodulatory effect of Hawthorn extract in an experimental stroke model  

PubMed Central

Background Recently, we reported a neuroprotective effect for Hawthorn (Crataegus oxyacantha) ethanolic extract in middle cerebral artery occlusion-(MCAO) induced stroke in rats. The present study sheds more light on the extract's mechanism of neuroprotection, especially its immunomodulatory effect. Methods After 15 days of treatment with Hawthorn extract [100 mg/kg, pretreatment (oral)], male Sprague Dawley rats underwent transient MCAO for 75 mins followed by reperfusion (either 3 or 24 hrs). We measured pro-inflammatory cytokines (IL-1?, TNF-?, IL-6), ICAM-1, IL-10 and pSTAT-3 expression in the brain by appropriate methods. We also looked at the cytotoxic T cell sub-population among leukocytes (FACS) and inflammatory cell activation and recruitment in brain (using a myeloperoxidase activity assay) after ischemia and reperfusion (I/R). Apoptosis (TUNEL), and Bcl-xL- and Foxp3- (Treg marker) positive cells in the ipsilateral hemisphere of the brain were analyzed separately using immunofluorescence. Results Our results indicate that occlusion followed by 3 hrs of reperfusion increased pro-inflammatory cytokine and ICAM-1 gene expressions in the ipsilateral hemisphere, and that Hawthorn pre-treatment significantly (p ? 0.01) lowered these levels. Furthermore, such pre-treatment was able to increase IL-10 levels and Foxp3-positive cells in brain after 24 hrs of reperfusion. The increase in cytotoxic T cell population in vehicle rats after 24 hrs of reperfusion was decreased by at least 40% with Hawthorn pretreatment. In addition, there was a decrease in inflammatory cell activation and infiltration in pretreated brain. Hawthorn pretreatment elevated pSTAT-3 levels in brain after I/R. We also observed an increase in Bcl-xL-positive cells, which in turn may have influenced the reduction in TUNEL-positive cells compared to vehicle-treated brain. Conclusions In summary, Hawthorn extract helped alleviate pro-inflammatory immune responses associated with I/R-induced injury, boosted IL-10 levels, and increased Foxp3-positive Tregs in the brain, which may have aided in suppression of activated inflammatory cells. Such treatment also minimizes apoptotic cell death by influencing STAT-3 phosphorylation and Bcl-xL expression in the brain. Taken together, the immunomodulatory effect of Hawthorn extract may play a critical role in the neuroprotection observed in this MCAO-induced stroke model. PMID:21192826

2010-01-01

35

Triterpenic Acids Present in Hawthorn Lower Plasma Cholesterol by Inhibiting Intestinal ACAT Activity in Hamsters  

PubMed Central

Hawthorn (Crataegus pinnatifida) is an edible fruit used in traditional Chinese medicine to lower plasma lipids. This study explored lipid-lowering compounds and underlying mechanisms of action of hawthorn. Hawthorn powder extracts inhibited acylCoA:cholesterol acyltransferase (ACAT) activity in Caco-2 cells. The inhibitory activity was positively associated with triterpenic acid (i.e., oleanolic acid (OA) and ursolic acid (UA)) contents in the extracts. Cholesterol lowering effects of hawthorn and its potential additive effect in combination with plant sterol esters (PSE) were further studied in hamsters. Animals were fed a semi-synthetic diet containing 0.08% (w/w) cholesterol (control) or the same diet supplemented with (i) 0.37% hawthorn dichloromethane extract, (ii) 0.24% PSE, (iii) hawthorn dichloromethane extract (0.37%) plus PSE (0.24%) or (iv) OA/UA mixture (0.01%) for 4 weeks. Compared to the control diet, hawthorn, PSE, hawthorn plus PSE and OA/UA significantly lowered plasma non-HDL (VLDL + LDL) cholesterol concentrations by 8%, 9%, 21% and 6% and decreased hepatic cholesterol ester content by 9%, 23%, 46% and 22%, respectively. The cholesterol lowering effects of these ingredients were conversely associated with their capacities in increasing fecal neutral sterol excretion. In conclusion, OA and UA are responsible for the cholesterol lowering effect of hawthorn by inhibiting intestinal ACAT activity. In addition, hawthorn and particularly its bioactive compounds (OA and UA) enhanced the cholesterol lowering effect of plant sterols. PMID:19228775

Lin, Yuguang; Vermeer, Mario A.; Trautwein, Elke A.

2011-01-01

36

Screening low fire blight susceptible Crataegus species for host suitability to hawthorn leaf-curling aphids (Dysaphis spp.).  

PubMed

The group of hawthorn leaf-curling aphids (Dysaphis spp.) hosted by the common hawthorn Crataegus monogyna Jacq. may play an important role in the biological control of the rosy apple aphid, Dysaphis plantaginea (Passerini), by increasing reproduction opportunities for the indigenous hymenopteran parasitoid Ephedrus persicae Froggatt. Unfortunately, most fruitgrowers hesitate to introduce the common hawthorn in their orchards because they fear fire blight infections which may be transmitted by this highly susceptible hawthron species. This potential hazard led us to investigate the suitability to leaf-curling aphids of alternative Crataegus species. As representative for these closely-related aphids, the species Dysaphis apiifolia petroselini (Börner) was used in the trials. Ten Crataegus species characterized by their very low susceptibility to fire blight were examined from two angles. Firstly, aphid sexuals were introduced in autumn onto the different species to verify whether egg laying could take place. Secondly, the development of fundatrices and gall formation were followed the next spring. Although eggs and mature fundatrices could be obtained on almost all species, no fundatrice-hosting galls were recorded in spring. The possible causes of these negative results with respect to the geographical origin of the particular Crataegus species involved in this work are discussed. PMID:12696414

Bribosia, E; Bylemans, D; Van Impe, G; Migon, M

2002-01-01

37

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

PubMed

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 the plant. Aqueous ethanolic extracts of single-styled hawthorn (Crataegus monogyna Jacq., f.: Rosaceae Juss.) leaves and sprouts were analyzed by means of capillary zone electrophoresis (CZE). Influence of vegetation period on the extract qualitative composition and flavonoids quantities was evaluated. Sample preparation by extraction using different concentration of aqueous ethanol (40-96%, v/v) and the influence of extractant composition on the recovery of flavonoids are discussed in detail. The results obtained using CZE are compared to the results of spectrophotometric and HPLC analysis of the extracts. The effect of storage conditions of extracts (solar irradiation, temperature and duration) on degradation of flavonoids was investigated. PMID:16443232

Urbonavici?te, A; Jakstas, V; Kornysova, O; Janulis, V; Maruska, A

2006-04-21

38

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

Microsoft Academic Search

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

L. J. Gut; J. F. Brunner

1994-01-01

39

Hawthorn ( Crataegus monogyna Jacq.) extract exhibits atropine-sensitive activity in a cultured cardiomyocyte assay  

Microsoft Academic Search

Hawthorn (Crataegus spp.) plant extract is used as a herbal alternative medicine for the prevention and treatment of various cardiovascular diseases.\\u000a Recently, it was shown that hawthorn extract preparations caused negative chronotropic effects in a cultured neonatal murine\\u000a cardiomyocyte assay, independent of beta-adrenergic receptor blockade. The aim of this study was to further characterize the\\u000a effect of hawthorn extract to

Satin Salehi; Shannon R. Long; Philip J. Proteau; Theresa M. Filtz

2009-01-01

40

Genetic Relationships Among Some Hawthorn ( Crataegus spp.) Species and Genotypes  

Microsoft Academic Search

The genus Crataegus is well distributed in Turkey as a wild plant, with numerous, inherently variable species and genotypes. RAPD markers were\\u000a used to study 17 hawthorn genotypes belonging to Crataegus monogyna ssp. monogyna Jacq (2 genotypes), C. monogyna ssp. azarella Jacq (1), Crataegus pontica K.Koch (3), Crataegus orientalis var. orientalis Pallas Ex Bieb (3), Crataegus pseudoheterophylla Pojark (1), Crataegus

Kadir Ugurtan Yilmaz; Makbule Yanar; Sezai Ercisli; Hatice Sahiner; Tuncer Taskin; Yasar Zengin

2010-01-01

41

The Miocene Atlantic Ocean  

NASA Astrophysics Data System (ADS)

We model paleoclimate and ocean circulation during the Miocene climatic optimum (~17 ¬ 14.5 Ma) using the Community Climate System Model 3 (CCSM3), focussing particularly on the effect of Miocene model boundary conditions including reconstructed topography, bathymetry, and vegetation. The modelled Miocene climate exhibits broad increases in mean annual precipitation over central and northern Africa, northern Eurasia, northern North America and Greenland compared to the present. In northern Africa, summer precipitation is significantly higher in the Miocene due to the replacement of desert with broadleaf vegetation, consistent with previously published sensitivity studies. Our results qualitatively support interpretations of carbon and neodymium isotope records indicating NCW formation in the North Atlantic as well as a dominant bottom water source in the Southern Ocean. Major tectonic changes in our Miocene Atlantic bathymetry compared to the present day are the severe constriction of the Fram Strait, closure of the Panama Strait and the less elevated Greenland-Scotland Ridge. We find that the structure of ocean circulation in the Miocene Atlantic is somewhat opposite to the present day, with the primary region of Miocene bottom water formation in the Weddell Sea. The strength of Weddell Sea bottom water and North Component Water (NCW) formation are moderated by atmospheric CO2 levels, which suggests that very weak NCW formation could have existed under significantly higher concentrations than the present-day CO2 concentration used in our model. Such a state would be consistent with the hypothesis of negligible NCW formation in the early Miocene, suggested previously. In our model, the NCW is relatively warm and saline compared to modern North Atlantic Deep Water (NADW). This is likely a robust result, caused by a northward deflection of North Atlantic subtropical water below the mixed-layer, a weakening of the subpolar gyre and weaker convection, as opposed to warm Tethys outflow. An interesting model result concerns the importance of the geometry of reconstructed gateways. Regarding the Panama gateway we find only a small eastward throughflow, in contrast in contrast with other published estimates. The difference appears to be related to the exact orientation of the reconstructed gateway. A gateway oriented in a zonal direction results in a natural extension of the equatorial countercurrent, whereas a more meridionally oriented gateway, as in our reconstruction, largely prohibits such a current, emphasizing the effect of subtle model boundary conditions. A decreased northern hemisphere ocean heat transport in the Miocene compared to the present is a result of a significant weakening of North Atlantic Deep Water formation. Modelled flow into the Arctic Ocean is consistent with the idea of an enclosed estuarine sea. Coupled with a relatively deeper Greenland-Scotland Ridge it permits substantial Miocene ocean warming. Determining how this warming varied under changes in modelled bathymetry may elucidate ways in which near ice-free Arctic conditions were sustainable.

Müller, R. D.; Herold, N.; Huber, M.

2012-04-01

42

Metal characterization of white hawthorn organs and infusions.  

PubMed

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

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

2015-02-18

43

Development of an economic model to assess the cost-effectiveness of hawthorn extract as an adjunct treatment for heart failure in Australia  

PubMed Central

Objective An economic model was developed to evaluate the cost-effectiveness of hawthorn extract as an adjunctive treatment for heart failure in Australia. Methods A Markov model of chronic heart failure was developed to compare the costs and outcomes of standard treatment and standard treatment with hawthorn extract. Health states were defined by the New York Heart Association (NYHA) classification system and death. For any given cycle, patients could remain in the same NYHA class, experience an improvement or deterioration in NYHA class, be hospitalised or die. Model inputs were derived from the published medical literature, and the output was quality-adjusted life years (QALYs). Probabilistic sensitivity analysis was conducted. The expected value of perfect information (EVPI) and the expected value of partial perfect information (EVPPI) were conducted to establish the value of further research and the ideal target for such research. Results Hawthorn extract increased costs by $1866.78 and resulted in a gain of 0.02 QALYs. The incremental cost-effectiveness ratio was $85?160.33 per QALY. The cost-effectiveness acceptability curve indicated that at a threshold of $40?000 the new treatment had a 0.29 probability of being cost-effective. The average incremental net monetary benefit (NMB) was ?$1791.64, the average NMB for the standard treatment was $92?067.49, and for hawthorn extract $90?275.84. Additional research is potentially cost-effective if research is not proposed to cost more than $325 million. Utilities form the most important target parameter group for further research. Conclusions Hawthorn extract is not currently considered to be cost-effective in as an adjunctive treatment for heart failure in Australia. Further research in the area of utilities is warranted. PMID:22942231

Ford, Emily; Adams, Jon; Graves, Nicholas

2012-01-01

44

Miocene Coralline algae  

SciTech Connect

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.

Bosence, D.W.J.

1988-01-01

45

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

Microsoft Academic Search

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

Christian Kjær; Morten Strandberg; Mogens Erlandsen

2006-01-01

46

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

Microsoft Academic Search

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

Yeh Hsueh

2002-01-01

47

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

Federal Register 2010, 2011, 2012, 2013, 2014

...11-AWP-10] Proposed Revision of Class D and Class E Airspace; Hawthorne, CA AGENCY...SUMMARY: This action proposes to revise Class D and E airspace at Jack Northrop Field/Hawthorne...Regulations (14 CFR) Part 71 by revising Class D airspace and Class E airspace...

2011-10-31

48

Antarctic Miocene Climate  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

49

The 2011 Hawthorne, Nevada, Earthquake Sequence; Shallow Normal Faulting  

NASA Astrophysics Data System (ADS)

An energetic sequence of shallow earthquakes that began in early March 2011 in western Nevada, near the community of Hawthorne, has slowly decreased in intensity through mid-2011. To date about 1300 reviewed earthquake locations have been compiled; we have computed moment tensors for the larger earthquakes and have developed a set of high-precision locations for all reviewed events. The sequence to date has included over 50 earthquakes ML 3 and larger with the largest at Mw 4.6. Three 6-channel portable stations configured with broadband sensors and accelerometers were installed by April 20. Data from the portable instruments is telemetered through NSL's microwave backbone to Reno where it is integrated with regional network data for real-time notifications, ShakeMaps, and routine event analysis. The data is provided in real-time to NEIC, CISN and the IRIS DMC. The sequence is located in a remote area about 15-20 km southwest of Hawthorne in the footwall block of the Wassuk Range fault system. An initial concern was that the sequence might be associated with volcanic processes due to the proximity of late Quaternary volcanic flows; there have been no volcanic signatures observed in near source seismograms. An additional concern, as the sequence has proceeded, was a clear progression eastward toward the Wassuk Range front fault. The east dipping range bounding fault is capable of M 7+ events, and poses a significant hazard to the community of Hawthorne and local military facilities. The Hawthorne Army Depot is an ordinance storage facility and the nation's storage site for surplus mercury. The sequence is within what has been termed the 'Mina Deflection' of the Central Walker Lane Belt. Faulting along the Whiskey Flat section of the Wassuk front fault would be primarily down-to-the-east, with an E-W extension direction; moment tensors for the 2011 earthquake show a range of extension directions from E-W to NW-SE, suggesting a possible dextral component to the Wassuk Range front fault at this latitude. At least two faults have been imaged within the sequence; these structures are at shallow depth (3-6 km), strike NE, and dip ~NW. Prior to temporary station installation event depths were poorly constrained, with the nearest network station 25 km from the source area. Early sequence moment tensor solutions show depths are on the order of 2-6 km and locations using the near source stations also confirm the shallow depths of the Hawthorne sequence. S-P times of 0.5 sec and less have been observed on a near-source station, illustrating extremely shallow source depths for some events. Along with the 2011 Hawthorne activity, very shallow depths in Nevada have been observed from near source stations in the 2008 west Reno earthquake sequence (primarily strike-slip faulting; main shock Mw 5.0) and the 1993 Rock Valley sequence in southern NNSS (strike-slip faulting; main shock Mw 4.0). These shallow sequences tend to include high rates of low magnitude earthquakes continuing over several months duration.

Smith, K. D.; Johnson, C.; Davies, J. A.; Agbaje, T.; Knezevic Antonijevic, S.; Kent, G.

2011-12-01

50

Review of Miocene larger foraminifera  

SciTech Connect

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.

Glenn, E.C.

1988-01-01

51

Longitudinal Variation in Terrestrial Oxygen Isotope Records of Modern Water and Mid-Miocene Authigenic Minerals: No Mid-Miocene Climatic Optimum in the Inland Pacific Northwest?  

Microsoft Academic Search

The stable isotopic compositions of benthic foraminifera quantitatively indicate that the middle Miocene climatic optimum was a period of global greenhouse conditions within the generally cooling and drying climatic trend in the past 65 million years. There are numerous red-colored weathering sequences preserved in intervolcanic paleosurfaces of the middle Miocene Columbia River Basalt Group. Even though most of the reddened

A. Takeuchi; P. B. Larson; K. Suzuki; A. J. Goodwin

2005-01-01

52

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

PubMed

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

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

2014-03-01

53

Miocene Antarctic Terrestrial Realm  

NASA Astrophysics Data System (ADS)

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.

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

2009-12-01

54

Calcareous Nannofossil Evolution Vs. Climatic Evolution In The Miocene  

NASA Astrophysics Data System (ADS)

Miocene times were characterized by major changes in ocean circulation and global climate that were driven by a complex set of factors operating on tectonic, orbital and suborbital timescales (Zachos et al., 2001). This time dependent development of Miocene paleo-environmental conditions is reflected in the distribution and evolutionary patterns, often expressed in terms of biostratigraphic resolution, among the dominant sediment-forming oceanic plankton groups (Kennett & Srinivasan, 1983; Baldauf & Barron, 1990; Perch-Nielsen, 1985) including calcareous nannofossils. In the Miocene through Pleistocene interval, calcareous nannofossil evolutionary appearances or extinctions provide eight biostratigraphically useful biohorizons between 23 Ma and 14 Ma, giving an average rate of 1.5 biohorizon per million years. In the next following eight million years (14-5 Ma), the number of biohorizons are 29 (3.6 biohorizons/million years), representing well over a doubling of the rate of taxonomic evolution among open ocean calcareous nannofossils compared with that of the early half of the Miocene. This observation demonstrates that a distinct evolutionary response to climatic evolution throughout the Miocene, specifically to changing conditions in the photic zone of the middle and late Miocene oceans. This assumption is supported by the behavior of some nannofossil groups, in particular by the representatives of the genus Discoaster, a key group that gives nearly half (14 of 29) of biohorizons in the younger half of the Miocene. The Discoaster's environmental distribution and abundance may provide some information about the complex interaction between climatic evolution and biotic evolution in the plankton realm.

Raffi, I.; Backman, J.; Ciummelli, M.

2013-12-01

55

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

PubMed

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

Hsueh, Yeh

2002-05-01

56

Miocene reef corals: A review  

SciTech Connect

Tectonic blockage in the Middle East of westward-flowing Tethys surface circulation during the latest Oligocene led to creation in the earliest Miocene of endemic Mediterranean, Western Atlantic-Caribbean, and Indo-Pacific realms. A great reduction in reef coral diversity from 60-80 Oligocene species to 25-35 early Miocene species occurred in the Western Atlantic-Caribbean and Mediterranean areas accompanied by a decrease in reef growth. A slower and less drastic change apparently occurred in the Indo-Pacific area. Early Miocene reef corals of the Western Atlantic-Caribbean comprise a transition between the cosmopolitan Oligocene fauna and its endemic mid-Miocene to modern counterpart. Although early Miocene reefs were dominated by a Porites-Montastrea assemblage, eastward flow of Pacific circulation brought with it ''exotic'' corals such as Coscinaraea and Pseudocolumnastrea. Also, many cosmopolitan genera persisted from the Oligocene. During the middle to late Miocene, most of the species still living on Holocene reefs evolved. As the Mediterranean basin became more restricted, there was a slow decline in reef corals from 20 - 25 species in the Aquitainian to less than five species in the Messinian. Eustatic lowstand led to the extinction of reef-building corals in the late Messinian. In the Indo-Pacific, Neogene evolution of reef corals was conservative. Excluding the Acroporidae and Seriatoporidae, most Holocene framework species had evolved by the middle Miocene. Interplay between regional tectonics and eustatic sea level changes led to extensive development of middle to late Miocene pinnacle reefs over the southwestern Pacific.

Frost, S.H.

1988-01-01

57

A macroecological glance at the structure of late Miocene rodent assemblages from Southwest Europe  

PubMed Central

Deep-time perspectives in macroecology are essential with regard to understanding the impact of climate forcing on faunal communities. Using late Miocene rodent faunas (12 to 5?Ma) from two different biogeographical provinces from southwestern Europe, we asked whether the waxing and waning of faunas with dissimilar ecological affinities tracked climate in different ways. The latest middle Miocene featured a fauna dominated by dormice with forest and mixed-habitat affinities. This group declined towards the Upper Miocene. Rodent taxa with the highest values of richness at the beginning of the Upper Miocene are generalists in the southern province and specialists of forested habitats in the northern province. Finally, we identified a third, increasingly significant group of rodents linked to open landscapes towards the end of the Miocene. These three broad ecological groups showed differential responses to a complex set of interconnected circumstances, including the biogeographic structure of the study area and climatic changes throughout time. PMID:25297009

Cano, Ana Rosa Gómez; Cantalapiedra, Juan L.; Álvarez-Sierra, M. Ángeles; Fernández, Manuel Hernández

2014-01-01

58

A macroecological glance at the structure of late Miocene rodent assemblages from Southwest Europe  

NASA Astrophysics Data System (ADS)

Deep-time perspectives in macroecology are essential with regard to understanding the impact of climate forcing on faunal communities. Using late Miocene rodent faunas (12 to 5 Ma) from two different biogeographical provinces from southwestern Europe, we asked whether the waxing and waning of faunas with dissimilar ecological affinities tracked climate in different ways. The latest middle Miocene featured a fauna dominated by dormice with forest and mixed-habitat affinities. This group declined towards the Upper Miocene. Rodent taxa with the highest values of richness at the beginning of the Upper Miocene are generalists in the southern province and specialists of forested habitats in the northern province. Finally, we identified a third, increasingly significant group of rodents linked to open landscapes towards the end of the Miocene. These three broad ecological groups showed differential responses to a complex set of interconnected circumstances, including the biogeographic structure of the study area and climatic changes throughout time.

Cano, Ana Rosa Gómez; Cantalapiedra, Juan L.; Álvarez-Sierra, M. Ángeles; Fernández, Manuel Hernández

2014-10-01

59

Miocene reefs of Dominican Republic  

SciTech Connect

The reefs are overlain by conglomeratic strata. The stratigraphic setting of these reefs suggests that they have developed along the stalled portions of rapidly prograding fan deltas. Thickets and layers of coral debris are found seaward and stratigraphically above the well-developed reef. The matrix sediments are exclusively fine-grained sand to mud, and the fauna are suggestive of more open shelf conditions. In thickets, branched (porites spp., Pocillopora spp.), small massive (Montastrea spp., Siderastrea spp.), and foliose or plate like (Agaricia spp.) corals are found upright in the muddy sediment. Similarities in coral species and areal proximity suggest that thickets are the source of most layers of coralline debris. The association of coral debris with graded bedding and cross-bedding suggests that coral debris has been reworked by storms. The growth of corals and development of coral reefs in the Miocene-Pliocene Yaque Group is limited only by opportunities created by the slowing of siliciclastic sedimentation. Soft, muddy, terrigenous substrates and a continuing supply of terrigenous mud exert only a limited, indirect effect on reef growth.

Evans, C.C.

1988-01-01

60

An overview of Miocene reefs  

SciTech Connect

Miocene reefs lived approximately within the latitudes of 27{degree}S to 48{degree}N compared with 25{degree}S and 32{degree}N for Holocene reefs. This expansion of reef-growing environments was the result of warm Miocene climates, aided by a eustatic sea level rise and tectonic styles that provided numerous foundations for reef development. The majority of Miocene reefs are found in three main areas: (1) Southeast Asia and the western Pacific, (2) the Mediterranean-Middle East, and (3) Middle America and the Caribbean. These regions, with their distinctive suites of coral and foramineral species, formed three biological provinces; respectively, they are the Indo-Pacific, Tethyan, and Western Atlantic provinces. Miocene reefs in Southeast Asia occur in several foreland basins as patch reef complexes on paleohighs and as barrier reefs in back-arc basins. Those reefs in the Mediterranean occur as fringing reefs, middle-shelf patch reefs, or as barrier reefs on the edges of tectonic blocks associated with Alpine thrust belts. Most reefs in the Caribbean grew on isolated open-ocean highs of volcanic origin. Miocene reefs display a diversity of framework types: (1) coral-encrusting, red algal boundstones with diverse coral faunas, (2) branching coral-encrusting, red algal boundstones with a limited Poritid fauna, (3) encrusting red algal boundstones. Barrier reef systems are especially rich in encrusting red algae and robust corals; grainstones are common as interbedded sediment. Patch reef complexes, however, display muddy carbonate textures, may have less diverse coral faunas, and commonly have larger foraminifera. The global distribution of Miocene reefs is important because (1) it provides insight into a paleoclimatic view of the earth during a major greenhouse stage and (2) Miocene buildups, such as the Arun (EUR of 14 tcf) and Bima fields (EUR of about 100 MMBO), are exploration targets.

Jordan, C.F. Jr. (Mobil Research and Development Corp., Dallas, TX (USA)); Colgan, M.W. (College of Charleston, SC (USA)); Frost, S.H. (Unocal, Los Angeles, CA (USA)); Glenn, E.C. (Phillips Petroleum, Bartlesville, OK (USA)); Bosence, D. (Royal Holloway and Bedford New College, Egham (England)); Esteban, M. (ERICO Petroleum Information Ltd., London (England))

1990-05-01

61

Apatite (U-Th)/He Thermochronometry as an innovative Geothermal Exploration Tool - A case study from the Wassuk Range, Hawthorne, Nevada  

NASA Astrophysics Data System (ADS)

A utility-grade geothermal system requires increased, near-surface temperatures (>120°C), water to transfer heat, and structural or sedimentological fluid conduits. In extensional tectonic settings, geothermal anomalies often occur in areas with recent, high strain accumulation and complex faulting (i.e., cross-faults, accommodation zones) where exhumation and uplift of footwall rocks transfer heat, via advection, to the near-surface which is further carried by water through structural fluid conduits. Apatite helium (AHe) thermochronometric footwall age mapping can be used in conjunction with these genetic occurrence models to further focus regional-scale geothermal exploration efforts to areas of probabilistic increased fracture permeability and most recent, rapid footwall exhumation. Furthermore, partially reset apatites resulting from interaction with hydrothermal fluids (>40°C) will show which areas have been hottest most recently. This case study in the Wassuk Range, Hawthrone, NV confirms the utility of AHe thermochronometry as a geothermal exploration tool. A dense grid of footwall samples were collected adjacent to the Hawthorne geothermal anomaly (>85°C BHT) located in the hanging wall of the Wassuk Range block. Our data show that the location of the present-day geothermal anomaly correlates with the location of 1) the most recent episode of rapid footwall exhumation at 3.5-4 Ma, 2) km scale accommodation zones between differentially tilted Wassuk Range blocks, and 3) an elevated Miocene geothermal gradient. Furthermore, anomalously young AHe ages (<3.5 Ma) mimic the lateral extent of the Hawthorne geothermal anomaly and likely resulted from interaction with a deep-seated geothermal cell or hot hydrothermal fluids.

Gorynski, K. E.; Stockli, D. F.; Walker, J. D.

2010-12-01

62

The Burden of Secret Sin: Nathaniel Hawthorne's Fiction The fiction of Nathaniel Hawthorne has frequently been defined in musical terms on account of  

E-print Network

what happens with The Scarlet Letter which ceased to be a stigma which attracted the world's scorn of openly and except the frequent allusions to adulteration, the text of The Scarlet Letter is more be found throughout Hawthorne's writings, in his earliest as well as in his latest. It is The Scarlet

Paris-Sud XI, Université de

63

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

PubMed

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

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

2009-03-01

64

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...

65

1, 167188, 2006 Late Miocene River  

E-print Network

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

Boyer, Edmond

66

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...

67

Comparative Protective Effect of Hawthorn Berry Hydroalcoholic Extract, Atorvastatin, and Mesalamine on Experimentally Induced Colitis in Rats  

PubMed Central

Abstract 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

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

2013-01-01

68

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

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

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

69

Changes in physicochemical characteristics and free amino acids of hawthorn (Crataegus pinnatifida) fruits during maturation.  

PubMed

In this study, changes in physicochemical characteristics associated with fruit quality and free amino acids were investigated during maturation of hawthorn fruits. Significant differences in these parameters were found during maturation. The color turned progressively from mature green to semi-red, to reach bright red; the shape changed gradually from oval to round or approached round; the size, weight, and edible part (flesh/core ratio) of hawthorns increased while the density of intact fruits did not change. The content of moisture, total soluble sugars, soluble pectin, reduced ascorbic acid, total ascorbic acid, fructose, and sucrose increased while crude protein content decreased significantly. The levels of starch, sucrose, titratable acidity, protopectin, pectin, total free amino acids, and total essential amino acids initially increased and then decreased gradually during maturation. The outcomes of this study provide additional and useful information for fresh consumption and processing as well as utilization of dropped unripe hawthorn fruits. PMID:25577050

Li, Wei-Qin; Hu, Qing-Ping; Xu, Jian-Guo

2015-05-15

70

Applied environmental stresses to enhance the levels of polyphenolics in leaves of hawthorn plants.  

PubMed

In this investigation, two species of Crataegus (hawthorn) were chosen because their polyphenolic constituents have recently received greater attention for the treatment of patients with severe heart disease. One-year-old plants of hawthorn (Crataegus laevigata and C. monogyna) were subjected to water-deficit (continuous water deprivation), cold (4 degrees C), flooding (immersion of roots of plants in water) or herbivory (leaf removal) stress treatments (each of 10 days duration) in order to assess their effects on levels of polyphenolics, namely (-)-epicatechin, catechin, chlorogenic acid, vitexin, vitexin-2"-O-rhamnoside, acetylvitexin-2"-O-rhamnoside, hyperoside, quercetin, and rutin in the leaves. The working hypothesis followed is that one or more of these stress treatment will elicit increases in the levels of these polyphenolics. Cold stress causes increases in levels of vitexin-2"-O-rhamnoside, acetylvitexin-2"-O-rhamnoside, hyperoside, and quercetin in both Crataegus species. Water-deficit stress increased the productivity of chlorogenic acid, catechin, and (-)-epicatechin in both hawthorn species. Flooding and herbivory caused no net increases, and in some cases, decreases in levels of polyphenolics. These studies indicate that either water-deficit stress or cold stress treatments, or a combination of the two, can be used to enhance the levels of desired polyphenolics in the leaves of these two hawthorn species in a photobioreactor system. These results may have significance for hawthorn in adapting to water-deficit or cold stress and are important considerations for the use of hawthorn in the treatment of heart disease in humans. PMID:15153184

Kirakosyan, Ara; Kaufman, Peter; Warber, Sara; Zick, Suzanna; Aaronson, Keith; Bolling, Steven; Chul Chang, Soo

2004-06-01

71

Diagenesis of the Oligocene-Miocene rocks of the Upper Floridan and Intermediate aquifer systems by meteoric and mixing-zone waters in southwest Florida  

SciTech Connect

Optical and SEM of samples from 6 cores of Oligocene and Miocene rocks that compose portions of the Florida and Intermediate aquifers and the intervening semiconfining unit documents meteoric and mixing-zone (seawater and fresh carbonate ground water) diagenesis inferred to have occurred over several cycles of sea level change. Dolomite, limestone, sandstone, and claystone of the Suwannee Formation and the Arcadia Formation (Hawthorn Group) were examined. Core samples from time-equivalent strata in two E--W transects in Manatee, Hardee, Highlands, Sarasota, and DeSoto Counties are estimated to be 16--33 Ma on the basis of [sup 87]Sr/[sup 86]Sr ratios from unaltered mollusk shells and by molluscan biostratigraphy. Lithostratigraphic correlations are based on examination of 19 cores, 62 thin sections, 60 geophysical logs, and mineralogy determined by X-ray diffraction. Diagenetic indicators that the authors tracked petrographically include shell micritization, shell dissolution, equant and (or) fibrous CaCO[sub 3] cement, neomorphism, dolomite, etched phosphate grains, echinoderm fragment syntaxial overgrowths, and amorphous silica pore lining. Infiltration of meteoric water caused dissolution of carbonate minerals, especially aragonite, and precipitation of equant calcite crystals in voids of dissolved fossils and in pore spaces between grains. The silica was precipitated as pore linings in zones having soil textures. Observed replacement of calcite by limpid dolomite is consistent with modeling predictions of mixing-zone diagenesis. Etched crystals of limpid dolomite may indicate freshwater dissolution of a mixing-zone precipitate. Mapping of regional unconformities revealed pronounced thickening and thinning of some units. Evidence of meteoric water diagenesis is observed in the upper 600 ft of the transects examined. Evidence of mixing-zone diagenesis is observed at varying depths, but appears to increase in abundance and thickness toward the west.

Weedman, S.D. (Pennsylvania State Univ., Univ. Park, PA (United States)); McCartan, L. (Geological Survey, Reston, VA (United States))

1993-03-01

72

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

Microsoft Academic Search

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)

Rex Sallabanks

1992-01-01

73

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

Microsoft Academic Search

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

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

2009-01-01

74

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

Federal Register 2010, 2011, 2012, 2013, 2014

...Docket No. 11-AWP-10] Revision of Class D and Class E Airspace; Hawthorne, CA AGENCY...SUMMARY: This action revises Class D and Class E airspace at Jack Northrop Field...the FAA. No comments were received. Class D airspace and Class E airspace...

2012-02-13

75

The Market Place of The Scarlet Letter: Hawthorne and Hester as Artist Objects  

Microsoft Academic Search

Like many of Nathaniel Hawthorne's fictional writings, The Scarlet Letter and its introduction ?The Custom House? consider the identity of the artist within both the public world of production and the private interior of the artist's self perception. However, this most celebrated text casts the artist uniquely, doubling the artist character in a purely fictional Hester Prynne and a fictionalized

Kerry Hasler-Brooks

76

Sex, lies and needlework: review of The scarlet letter (Nathaniel Hawthorne; movie directed by Roland Joffe)  

Microsoft Academic Search

I have an image of an extraterrestrial anthropologist holding a copy of Nathaniel Hawthorne's 1850 novel in one hand and a video tape of Roland Joff's 1995 film in the other. I imagine her examining these two versions of The Scarlet Letter as the only artefacts of human culture available to her. I can hear her baffled query: 'what could

A. Sutherland-Kelly

1997-01-01

77

spe438-20 page 1 Garrison, N.J., Busby, C.J., Gans, P.B., Putirka, K., and Wagner, D.L., 2008, A mantle plume beneath California? The mid-Miocene Lovejoy flood basalt, northern  

E-print Network

, A mantle plume beneath California? The mid-Miocene Lovejoy flood basalt, northern California, in Wright, J-Miocene Lovejoy flood basalt, northern California Noah J. Garrison Cathy J. Busby Phillip B. Gans Department to the Columbia River Basalt Group. Association of the Lovejoy basalt with mid-Miocene flood basalt volcanism has

Busby, Cathy

78

Assessment of phenolic acid content and in vitro antiradical characteristics of hawthorn.  

PubMed

The infusions and extracts obtained from leaves with flowers, fruit peel, and seed from hawthorn (Crataegus monogyna Jacq., Family Rosaceae) were subjected to evaluation as potential sources of antioxidant phytochemicals on the basis of their total content of phenolics, levels of phenolic acids, and in vitro antiradical activity. Total phenolic content of extracts was determined using the modified Folin-Ciocalteau method. Antioxidant activity was determined for phenolic extracts by a method involving the use of the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). Phenolic acids containing extracts and infusions from hawthorn leaves, fruit peel, and seeds were obtained using different polarity solvents and separated by reverse-phase high-performance liquid chromatography, which enabled improved separation by the use of a C(18) column, an acidic mobile phase, and gradient elusion. The highest total phenolic content (343.54?mg of gallic acid equivalents/g) and the highest DPPH radical scavenging activity as the inhibition percentage (60.36%) were obtained in ethyl acetate extract from hawthorn leaves with flower. Also, the highest phenolic acid content was measured in the extracts of hawthorn leaves with flowers: protocathechuic (108-128?mg/100?g), p-hydroxy benzoic (141-468?mg/100?g), caffeic (137-3,580?mg/100?g), chlorogenic (925-4,637?mg/100?g), ferulic (3,363-3,462?mg/100?g), vanillic (214?mg/100?g), and syringic (126?mg/100?g) acids. The results indicate that hawthorn is a promising plant because of its high antioxidant activity. PMID:21554133

Öztürk, Nilgün; Tunçel, Muzaffer

2011-06-01

79

Mediterranean Miocene carbonates: facies models and diagenesis  

SciTech Connect

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.

Esteban, M.E.

1987-11-01

80

MIOCENE AND PLIOCENE VERTEBRATES FROM ARIZONA  

Microsoft Academic Search

We present an overview of the Miocene and Pliocene vertebrates of Arizona, spanning the time period from about 2 to 20 Ma. The best known Miocene faunas are Wellton and Anderson Mine from the late Arikareean or Hemingfordian North American land-mammal \\

GARY S. MORGAN; RICHARD S. WHITE

2005-01-01

81

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

PubMed

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

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

2014-08-01

82

Miocene reefs in western Mediterranean  

SciTech Connect

Coral reefs were particularly abundant and well developed during the late Tortonian and Messinian in southeastern Spain, the Balearic Islands, Italy, Sicily, Algeria, and Morocco. These reefs occurred just before and during the deposition of the thick Messinian evaporite units in the basinal areas and disappeared completely from Mediteranean during the early Pliocene. Most of the coral reefs are fringing terrigenous coastal fan complexes with very small lagoons and show progradation of less than 2 km. Some of the reefs occur on, or are intercalated with, Neogene volcanics or Messinian evaporites. Barrier-reef complexes are less common, have extensive lagoons behind them, and show complex progradational geometries more than 10 km wide. Excellent outcrops allow detailed reconstruction of paleogeography and sea level changes. Progradation predominated during phases of relative sea level drops and stillsands, while significant retrogradation occurred during sea level rises. The coral reef wall framework is commonly less than 20 m thick and is dominated by Porites and, locally, Tarbellastrae. Older Miocene reefs are less well developed, but show greater diversity of corals and reef organisms. Younger Miocene reef complexes occurring in open ocean settings are formed by only one branching coral genus (Porites or, locally, Tarbellastraea) with branching colonies up to 7 m high. Halimeda sands are particularly abundant in the upper reef slopes with occasional intercalations of red algae pavements that most likely coincide with episodes of terrigenous influx.

Esteban, M.

1988-01-01

83

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

PubMed Central

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

Claus, Calvin K

2007-01-01

84

New primate genus from the Miocene of Argentina.  

PubMed

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

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

2006-04-01

85

Oxygen species scavenging activity of phenolic extracts from hawthorn fresh plant organs and pharmaceutical preparations.  

PubMed

Different extracts of fresh vegetative and reproductive organs from Crataegus monogyna harvested during a whole season and from some pharmaceutical hawthorn preparations exhibit in vitro antioxidant activities using three different models of oxygen reactive species generation (superoxide anion, hydrogen peroxide and hypochlorous acid). All the tested samples show low IC50 values, the most efficient being fresh young leaves, fresh floral buds and pharmaceutical dried flowers. The activities seem to be especially bound to the total phenolic proanthocyanidin and flavonoid contents. PMID:8955870

Bahorun, T; Gressier, B; Trotin, F; Brunet, C; Dine, T; Luyckx, M; Vasseur, J; Cazin, M; Cazin, J C; Pinkas, M

1996-11-01

86

The comparison of anti-oxidative kinetics in vitro of the fluid extract from maidenhair tree, motherwort and hawthorn.  

PubMed

The aim of the study was to perform a quantitative analysis of fluid extracts of maidenhair tree (Ginkgo biloba L.), motherwort (Leonurus cardiaca L.) and hawthorn (Crataegus monogyna Jacq.), to evaluate their antioxidant activity and to compare their ability to inactivate free radicals. The antioxidant activity was measured using the DPPH*and the ABTS*+ radical scavenging reaction systems. The study showed that the manifestation of the radical scavenging capacity in the DPPH* reaction system was in the following order: the fluid extract of hawthorn (70.37 +/- 0.80%) > the fluid extract of maidenhair tree (82.63 +/- 0.23%) > the fluid extract of motherwort (84.89 +/- 0.18%), while in the ABTS*+ reaction system, the manifestation of the radical scavenging capacity was in the following order: the fluid extract of hawthorn (87.09 +/- 0.55%) > the fluid extract of motherwort (88.28 +/- 1.06%) > the fluid extract of maidenhair tree (88.39 +/- 0.72%). The results showed that in the DPPH* reaction system, fluid extract of motherwort manifested higher antioxidant activity, compared to the fluid extracts of maidenhair tree and hawthorn. By contrast, in the ABTS*+ reaction system, higher antioxidant activity was found in the fluid extract of maidenhair tree, compared to the fluid extracts of motherwort and hawthorn. This would suggest that preparations manufactured from these herbal raw materials could be used as effective preventive means and valuable additional remedies in the treatment of diseases caused by oxidative stress. PMID:19702174

Bernatoniene, Jurga; Kucinskaite, Agne; Masteikova, Ruta; Kalveniene, Zenona; Kasparaviciene, Giedre; Savickas, Arunas

2009-01-01

87

Panafrican distribution of Lower Miocene Hominoidea  

NASA Astrophysics Data System (ADS)

Palaeontological survey of the Neogene littoral deposits of the Namaqualand coastal strip, Northern Cape Province, South Africa, has resulted in the collection of the first Lower Miocene faunas from South Africa. Among the mammals from Ryskop and Hondeklip Bay is a gorilla-sized hominoid. This discovery greatly increases the geographic range of early Miocene hominoids and suggests that even at this remote epoch, the superfamily had a Panafrican distribution.

Senut, Brigitte; Pickford, Martin; Wessels, Dudley

1997-11-01

88

Allopolyploidy, diversification, and the Miocene grassland expansion  

PubMed Central

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

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

89

Allopolyploidy, diversification, and the Miocene grassland expansion.  

PubMed

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

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

90

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

PubMed

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

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

2014-12-01

91

Additional material of the enigmatic Early Miocene mammal Kelba and its relationship to the order Ptolemaiida  

PubMed Central

Kelba quadeemae, a fossil mammal from the Early Miocene of East Africa, was originally named on the basis of three isolated upper molars. Kelba has previously been interpreted as a creodont, a pantolestid, an insectivoran, and a hemigaline viverrid. The true affinities of this taxon have remained unclear because of the limited material and its unique morphology relative to other Miocene African mammals. New material of Kelba from several East African Miocene localities, most notably a skull from the Early Miocene locality of Songhor in Western Kenya, permits analysis of the affinities of Kelba and documents the lower dentition of this taxon. Morphological comparison of this new material clearly demonstrates that Kelba is a member of the order Ptolemaiida, a poorly understood group whose fossil record was previously restricted to the Oligocene Fayum deposits of northern Egypt. Phylogenetic analysis supports the monophyly of the Ptolemaiida, including Kelba, and recovers two monophyletic clades within the order. We provide new family names for these groups and an emended diagnosis for the order. The discovery of ptolemaiidans from the Miocene of East Africa is significant because it extends the known temporal range of the order by >10 million years and the geographic range by >3,200 km. Although the higher-level affinities of the Ptolemaiida remain obscure, their unique morphology and distribution through a larger area of Africa (and exclusively Africa) lend support to the idea that Ptolemaiida may have an ancient African origin. PMID:17372202

Cote, Susanne; Werdelin, Lars; Seiffert, Erik R.; Barry, John C.

2007-01-01

92

Preliminary plan for the development of geothermal energy in the town of Hawthorne, Nevada  

SciTech Connect

Site characteristics pertinent to the geothermal development are described, including: physiography, demography, economy, and goals and objectives of the citizens as they relate to geothermal development. The geothermal reservoir is characterized on the basis of available information. The probable drilling depth to the reservoir, anticipated water production rates, water quality, and resource temperature are indicated. Uses of the energy that seem appropriate to the situation both now and in the near future at Hawthorne are described. The essential institutional requirements for geothermal energy development are discussed, including the financial, environmental, and legal and regulatory aspects. The various steps that are necessary to accomplish the construction of the geothermal district heating system are described.

Not Available

1981-11-04

93

Anti-inflammatory, gastroprotective, free-radical-scavenging, and antimicrobial activities of hawthorn berries ethanol extract.  

PubMed

Hawthorn [Crataegus monogyna Jacq. and Crataegus oxyacantha L.; sin. Crataegus laevigata (Poiret) DC., Rosaceae] leaves, flowers, and berries are used in traditional medicine in the treatment of chronic heart failure, high blood pressure, arrhythmia, and various digestive ailments, as well as geriatric and antiarteriosclerosis remedies. According to European Pharmacopoeia 6.0, hawthorn berries consist of the dried false fruits of these two species or their mixture. The present study was carried out to test free-radical-scavenging, anti-inflammatory, gastroprotective, and antimicrobial activities of hawthorn berries ethanol extract. Phenolic compounds represented 3.54%, expressed as gallic acid equivalents. Determination of total flavonoid aglycones content yielded 0.18%. The percentage of hyperoside, as the main flavonol component, was 0.14%. With respect to procyanidins content, the obtained value was 0.44%. DPPH radical-scavenging capacity of the extract was concentration-dependent, with EC50 value of 52.04 microg/mL (calculation based on the total phenolic compounds content in the extract). Oral administration of investigated extract caused dose-dependent anti-inflammatory effect in a model of carrageenan-induced rat paw edema. The obtained anti-inflammatory effect was 20.8, 23.0, and 36.3% for the extract doses of 50, 100, and 200 mg/kg, respectively. In comparison to indomethacin, given in a dose producing 50% reduction of rat paw edema, the extract given in the highest tested dose (200 mg/kg) showed 72.4% of its activity. Gastroprotective activity of the extract was investigated using an ethanol-induced acute stress ulcer in rats with ranitidine as a reference drug. Hawthorn extract produced dose-dependent gastroprotective activity (3.8 +/- 2.1, 1.9 +/- 1.7, and 0.7 +/- 0.5 for doses of 50, 100, and 200 mg/kg, respectively), with the efficacy comparable to that of the reference drug. Antimicrobial testing of the extract revealed its moderate bactericidal activity, especially against gram-positive bacteria Micrococcus flavus, Bacillus subtilis, and Lysteria monocytogenes, with no effect on Candida albicans. All active components identified in the extract might be responsible for activities observed. PMID:18698794

Tadi?, Vanja M; Dobri?, Silva; Markovi?, Goran M; Dordevi?, Sofija M; Arsi?, Ivana A; Menkovi?, Nebojsa R; Stevi?, Tanja

2008-09-10

94

Miocene reef carbonates of Mariana Islands  

SciTech Connect

Miocene carbonates in the southern Mariana Islands are impressive for their lithologic diversity, thicknesses (over 250 m), and geographic extent (> 20% combined outcrop coverage over four major high islands: Guam, Rota, Tinian and Saipan). Sections are dominated either by lagoonal algal-foraminiferal wackestones and mudstones with locally abundant high-energy shelly-skeletal facies, or by rubbly to muddy, fore-reef-to-bank deposits of packstones and grainstones with highly diverse and variable biogenic clasts. Fresh to deeply weathered volcaniclastic material may comprise at least 80% of some high-energy fore-reef facies, whereas lagoonal and bank deposits usually contain less than 0.5% terrigenous material. Surprisingly, the Miocene in the Marianas lacks almost completely any reef-core facies. Several poorly developed coral-rich mounds on Saipan and localized laminated red algal buildups on Guam appear to constitute the extant reef-wall facies in the Miocene. The lack of buildups may be a matter of differential survival; it may result from headland erosion and benching associated with emergence of narrow reef tracts as has been postulated by others for south Guam. Alternatively, the authors are proposing that Miocene bathymetry and the volume of terrigenous influx militated against significant reef core formation. Radiometric age dating of these reef carbonates has proven unsuccessful because pervasive diagenesis has transformed the entire Miocene section into low-magnesium calcite with minor and occasional dolomite. Freshwater phreatic diagenesis accounts for the principal porosity variation and trace element distribution.

Siegrist, H.G. Jr.

1988-02-01

95

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

PubMed

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 leaves was measured by means of a tracer (glycine). Spraying was conducted both at the bud stage and at early flowering. Leaves, flowers, green berries and mature berries were harvested and the number and weight of each were measured. The spraying at the bud stage caused a highly significant reduction in number and dry weight of berries, whereas it had no effects on leaf and flower production. The berry reduction was close to 100% at actual depositions relevant for spray drift under normal conditions. Spraying at early flowering also significantly reduced berries although the effect was smaller than for the spraying at bud stage. The early flower stage spraying caused no reduction in number and size of leaves. The possible ecological consequence is that metsulfuron spray drift from agricultural fields has a potential to reduce the amount of berries available for frugivorous birds in nearby hedgerows. A potential need for regulatory measures to reduce herbicide spray drift to hedgerows situated near agricultural fields with herbicide use is also indicated. PMID:15893364

Kjaer, Christian; Strandberg, Morten; Erlandsen, Mogens

2006-03-01

96

Preliminary plan for the development of geothermal energy in the town of Hawthorne, Nevada  

SciTech Connect

The results of the analyses as well as a plan for the development of the geothermal resource are described. Site characteristics pertinent to the geothermal development are described. These characteristics include physiography, demography, economy, and goals and ojectives of the citizens as they would relate to geothermal development. The geothermal resource is described. The reservoir is characterized on the basis of available information. The probable drilling depth to the reservoir, anticipated water production rates, water quality, and resource temperatures ae indicated. Uses of the energy that seem appropriate to the situation both now and in the near future at Hawthorne are described. The amounts and types of energy currently consumed by end users are estimated. Using this data base, conceptual engineering designs and cost estimates for three alternative district heating systems are presented. In addition, the results of a life cycle cost analysis for these alternatives are discussed. The essential institutional requirements for geothermal energy development, including the financial, environmental, and legal and regulatory aspects are discussed. The various steps that are necessary to accomplish the construction of the geothermal district heating system at Hawthorne are described. A time-line chart shows the tasks, the time estimated to be required for each, and the interrelationships among the activities.

Not Available

1981-11-04

97

Systematic review of the Hawthorne effect: New concepts are needed to study research participation effects?  

PubMed Central

Objectives This study aims to (1) elucidate whether the Hawthorne effect exists, (2) explore under what conditions, and (3) estimate the size of any such effect. Study Design and Setting This systematic review summarizes and evaluates the strength of available evidence on the Hawthorne effect. An inclusive definition of any form of research artifact on behavior using this label, and without cointerventions, was adopted. Results Nineteen purposively designed studies were included, providing quantitative data on the size of the effect in eight randomized controlled trials, five quasiexperimental studies, and six observational evaluations of reporting on one's behavior by answering questions or being directly observed and being aware of being studied. Although all but one study was undertaken within health sciences, study methods, contexts, and findings were highly heterogeneous. Most studies reported some evidence of an effect, although significant biases are judged likely because of the complexity of the evaluation object. Conclusion Consequences of research participation for behaviors being investigated do exist, although little can be securely known about the conditions under which they operate, their mechanisms of effects, or their magnitudes. New concepts are needed to guide empirical studies. PMID:24275499

McCambridge, Jim; Witton, John; Elbourne, Diana R.

2014-01-01

98

Paleoecology of an early Miocene, rapidly submerging rocky shore, Motuketekete Island, Hauraki Gulf, New Zealand  

Microsoft Academic Search

More than 70 macrofossil taxa (including 14 bivalves, 6 gastropods, 8 corals, 4 echinoderms, and 10 barnacles) are recorded from early Miocene (Otaian) Kawau Subgroup strata (Cape Rodney Formation and Motuketekete Limestone, lower Waitemata Group) at Motuketekete Island, Hauraki Gulf, north of Auckland City. Both in situ and transported fossils occur in deposits of greywacke boulder conglomerate, cobble to pebble

K. A. Campbell; J. S. Buckeridge; N. Hudson; A. C. Alfaro; J. Hoverd; S. Morgan; N. Horne; A. Banfield

2004-01-01

99

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

Microsoft Academic Search

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

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

2005-01-01

100

Application of (U-Th)/He thermochronometry as a geothermal exploration tool in extensional tectonic settings: the Wassuk Range, Hawthorne, Nevada  

E-print Network

and Gans, 1995; Surpless, 1999). Mesozoic metavolcanics and plutonic rocks in the central Wassuk Range are nonconformably overlain by Oligocene to Miocene age silicic ash-flow tuffs (e.g., Mickey Pass and Singaste), andesite flows (e.g., Lincoln Flat... Andesite) and later Tertiary Wassuk Group sediments and ashflow tuffs. The onset of crustal extension in the Wassuk Range was accommodated along east-dipping, high-angle nor- mal faults and is bracketed by the westward tilting of the overlying...

Gorynski, Kyle; Stockli, Daniel F.; Walker, J. Douglas; Sabin, Andrew

2010-01-01

101

Miocene Mammalian footprints in coprolites from Lisbon, Portugal  

Microsoft Academic Search

For the first time, at least for the Lisbon Miocene series, uncommon ichnologic evidence has been recognized, i.e. mammalian footprints in coprolites. Three coprolites were recorded in three successive stratigraphic units, IVb and Va2 from the Lower Miocene to Vb from the early Middle Miocene. The largest, tridactyl footprint can be ascribed to a right foot of a rhinoceros. Size

Miguel Telles Antunes; Ausenda C. Balbino; Léonard Ginsburg

2006-01-01

102

The Late Miocene climate response to a modern Sahara desert  

Microsoft Academic Search

The climate cooling and vegetation changes in the Miocene\\/Pliocene are generally well documented by various proxy data. Some important ecosystem changes occurred at that time. Palaeobotanical evidence suggests that the Sahara desert first appeared in the Pliocene, whereas in the Miocene North Africa was green. In the present study, we investigate the Late Miocene climate response to the appearance of

Arne Micheels; Jussi Eronen; Volker Mosbrugger

2009-01-01

103

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

PubMed Central

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

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

2013-01-01

104

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

Microsoft Academic Search

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

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

2000-01-01

105

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

Microsoft Academic Search

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.

P. J Croxton; T. H Sparks

2002-01-01

106

An Even Better Solution to the Paradox of the Ravens James Hawthorne and Branden Fitelson (7/23/2010)  

E-print Network

An Even Better Solution to the Paradox of the Ravens James Hawthorne and Branden Fitelson (7/23/2010) Think of confirmation in the context of the Ravens Paradox this way. The likelihood ratio measure of incremental confirmation gives us, for an observed Black Raven and for an observed non-Black non-Raven

Fitelson, Branden

107

Miocene reef carbonates of Mariana Islands  

SciTech Connect

Miocene carbonates in the southern Mariana Islands are impressive for their lithologic diversity, thicknesses (over 250 m), and geographic extend (>20% combined outcrop coverage over four major high islands: Guam, Rota, Tinian and Saipan). Sections are dominated either by lagoonal algal-foraminiferal wackestones and mudstones with locally abundant high-energy shelly-skeletal facies, or by rubbly to muddy, fore-reef-to-bank deposits of packstones and grainstones with highly diverse and variable biogenic clasts. Fresh to deeply weathered volcaniclastic material may comprise at least 80% of some high-energy fore-reef facies, whereas lagoonal and bank deposits usually contain less than 0.5% terrigenous material. Surprisingly, the Miocene in the Marianas lacks almost completely any reef-core facies. Several poorly developed coral-rich mounds on Saipan and localized laminated red algal buildups on Guam appear to constitute the extant reef-wall facies in the Miocene. The lack of buildups may be a matter of differential survival; it may result from headland erosion and benching associated with emergency of narrow reef tracts as has been postulated by others for south Guam. Radiometric age dating of these reef carbonates has proven unsuccessful because pervasive diagenesis has transformed the entire Miocene section into low-magnesium calcite with minor and occasional dolomite. Freshwater phreatic diagenesis accounts for the principal porosity variation and trace element distribution.

Siegrist, H.G. Jr.

1988-01-01

108

Murky details of the Miocene Atlantic Ocean  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

109

Antarctic hydrology during mid-Miocene warmth  

NASA Astrophysics Data System (ADS)

The Middle Miocene Climatic Optimum (MMCO) represents a period of global warmth 17-15 million years ago which resulted in the regrowth of vegetation on regions of Antarctica that were ice-covered since the Oligocene. A recent drilling campaign on the Antarctic ice shelf (ANDRILL SMS program) recovered middle Miocene sediments provided a first glimpse of a vegetated Antarctica at this time (Warny et al., 2009). However the hydrological regimes of Middle Miocene climate that enabled this vegetation expansion are not yet precisely known. Here we report leaf wax hydrogen isotope values of -170 to -120% indicate dD values for precipitation of -80 to -20% during the Middle Miocene. These values are significantly less negative than modern precipitation and together with microfossil evidence for warm, sea ice-free conditions, suggest an enhanced moisture flux. Experiments with isotopic tracers in idealized models under warm, ice free conditions indicate physical and dynamical support for 'heavy' polar precipitation isotopes reconstructed here. Pollen and biomarker abundances indicate peak conditions at 16.4 and 15.7Ma coeval with global anomalies of the MMCO (Zachos et al., 2001). Our results indicate increased moisture delivery to the Antarctic continent and an invigoration of meridional circulation and poleward latent heat flux during global warmth.

Feakins, S. J.; Warny, S.; Lee, J.

2011-12-01

110

North American Miocene land mammals from Panama  

Microsoft Academic Search

Miocene land mammals are described from the Gaillard Cut Local Fauna based on a collection made by Stewart and Whitmore in the 1960s from Cucaracha Reach, former Canal Zone, Republic of Panama. In addition to the Order Rodentia described elsewhere, the land mammals represent three other orders (Carnivora [new record], Artiodactyla, Perissodactyla), including the canid Tomarctus brevirostris, indeterminant Amphicyonidae or

Bruce J. Macfadden

2006-01-01

111

Longitudinal Variation in Terrestrial Oxygen Isotope Records of Modern Water and Mid-Miocene Authigenic Minerals: No Mid-Miocene Climatic Optimum in the Inland Pacific Northwest?  

NASA Astrophysics Data System (ADS)

The stable isotopic compositions of benthic foraminifera quantitatively indicate that the middle Miocene climatic optimum was a period of global greenhouse conditions within the generally cooling and drying climatic trend in the past 65 million years. There are numerous red-colored weathering sequences preserved in intervolcanic paleosurfaces of the middle Miocene Columbia River Basalt Group. Even though most of the reddened layers were considered as thermally altered `baked' zones by the overlying basalt flows, many of them show much evidence of pedogenesis. Thus, it was suggested that these lateritic weathering horizons are products of intense chemical weathering under humid and temperate paleoclimate conditions in the inland Pacific Northwest during the middle Miocene climatic optimum. However, these weathering sequences are only common around the Blue Mountains region in southeastern Washington, Oregon, and Idaho, where modern mean annual precipitation is relatively higher than the surrounding basins. Therefore, we hypothesize that the observed intense chemical weathering is the result of higher mean annual precipitation due to the orographic effect in the Blue Mountains area. The orographic effect is associated with higher altitude than surroundings in an upwind region. Four mid-Miocene spectacular thick reddish paleosols on top of Columbia River basalt flows were found at nearly the same latitude of 46°N but with different longitudes, ranging from 116°W to 120°W. Authigenic minerals at depths greater than 50 cm below the overlying basaltic flows were collected at each location, and also, for comparison, several surface water samples were collected to determine the modern hydrologic isotopic conditions along the transect. The measured ?18O values of modern surface water show a negative shift of approximately 5‰ from west to east in the study area, and the observed negative shift within the ?18O authigenic mineral values is similar (~4.5‰). Using equilibrium fractionation equations, the estimated paleo-temperatures are also similar to the modern temperatures along the transect. Thus, the regional climate has not been changes significantly since the mid-Miocene. It is likely that topography of the study area in the Blue Mountains region has not been significantly changed either since at least late Miocene. The basalt stratigraphy also indicates that there was a tectonic uplift in the Blue Mountains area during the mid- to late-Miocene.

Takeuchi, A.; Larson, P. B.; Suzuki, K.; Goodwin, A. J.

2005-12-01

112

Phytochemical characterization of several hawthorn (Crataegus spp.) species sampled from the Eastern Mediterranean region of Turkey  

PubMed Central

Background: We evaluated the total phenolic content, antioxidant capacity as well as antioxidant activity of five Crataegus species (A1, A2, Y1, Y2, Y4 accessions of Crataegus aronia var. aronia; B2, B3, B5, B6, B7, B9, Y5 accessions of C. aronia var. dentata; B10 accession of C. aronia var. minuta; Y3 accession of Crataegus orientalis var. orientalis and A3 accession of Crataegus monogyna subsp. azarella). Materials and Methods: Antioxidant activity and total phenolic content of fruits were determined by ?-carotene bleaching and Folin–Ciocalteu assays. Antioxidant capacity was determined by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Results: C. monogyna subsp. azarella had the highest total phenol, antioxidant activity and antioxidant capacity of 55.2 mg gallic acid equivalents (GAE)/g dry weight (DW), 81.9% and 31.2%, respectively. C. aronia var. aronia was found to have the lowest total phenolic content (35.7 mg GAE/g DW). The antioxidant activities of fruit extracts increased in the order of C. orientalis var. orientalis < C. aronia var. minuta < C. aronia var. dentata < C. aronia var. aronia < C. monogyna subsp. azarella according to ?-carotene/linoleic acid assay. In recent years, C. aronia var. dentata has gained importance as a commercial species in this region. B3 and B7 accessions had fruit weight more than 14 g, and considerable total phenol content, antioxidant activity and antioxidant capacity. Conclusion: This investigation shows the potential value of hawthorn fruit species as a good source of natural antioxidants and that consumption of hawthorn fruit or its products may contribute substantial amounts of antioxidants to the diet. PMID:22438658

Çali?kan, O?uzhan; Gündüz, Kazim; Serçe, Sedat; Toplu, Celil; Kamilo?lu, Önder; ?engül, Memnune; Erci?li, Sezai

2012-01-01

113

"A strong mind in a sane body": the role of physical activity in the lives and writings of Sophia Hawthorne, Margaret Fuller, and Kate Chopin  

E-print Network

"A STRONG MIND IN A SANE BODY": THE ROLE OF PHYSICAL ACTIVITY IN THE LIVES AND WRITINGS OF SOPHIA HAWTHORNE~ MARGARET FULLER, AND KATE CHOPIN A Thesis by LEANN MILLER WILLOUGHBY Submitted to the Office of Graduate Studies of Texas ASM... University in partial fulfillment of the requirements for the degree of MASTER OF ARTS August 1992 Major Subject: English ?A STRONG MIND IN A SANE BODY? . THE ROLE OF PHYSICAL ACTIVITY IN THE LIVES AND WRITINGS OF SOPHIA HAWTHORNE, MARGARET FULLER...

Willoughby, Leann Miller

1992-01-01

114

Miocene Soil Database: Global paleosol and climate maps of the Middle Miocene Thermal Maximum  

NASA Astrophysics Data System (ADS)

Paleosols, which record past climatic, biologic, and atmospheric conditions, can be used as a proxy to understand ancient terrestrial landscapes, paleoclimate, and paleoenvironment. In addition, the middle Miocene thermal maximum (~16 Ma) provides an ancient analog for understanding the effects of current and future climate change on soil and ecosystem regimes, as it contains records of shifts similar in magnitude to expected global climate change. The Miocene Soil Database (MSDB) combines new paleosol data from Australia and Argentina with existing and previously uncollated paleosol data from the literature and the Paleobiology Database. These data (n = 507) were then used to derive a paleogeographic map of climatically significant soil types zones during the Middle Miocene. The location of each diagnostic paleosol type (Aridisol, Alfisol, Mollisol, Histosol, Oxisol, and Ultisol) was plotted and compared with the extent of these soil types in the modern environment. The middle Miocene soil map highlights the extension of tropical soils (Oxisols, Ultisols), accompanied by thermophilic flora and fauna, into northern and southern mid-latitudes. Peats, lignites, and Histosols of wetlands were also more abundant at higher latitudes, especially in the northern hemisphere, during the middle Miocene. The paleosol changes reflect that the Middle Miocene was a peak of global soil productivity and carbon sequestration, with replacement of unproductive Aridisols and Gelisols with more productive Oxisols, Alfisols, Mollisols and Histosols. With expansion to include additional data such as soil texture, moisture, or vegetation type, the MSDB has the potential to provide an important dataset for computer models of Miocene climate shifts as well as future land use considerations of soils in times of global change.

Metzger, C. A.

2013-12-01

115

Global Miocene tectonics and the modern world  

NASA Astrophysics Data System (ADS)

An amazing congruence of seemingly unrelated, diverse global events began in the Middle and Upper Miocene and established our modern world. Two global orogenic belts were active, mostly in the Middle and Upper Miocene, while backarc basins formed along the eastern margin of Asia. Coincident with these events global temperatures cooled in both the ocean and atmosphere, desertification occurred from Central Asia into and across most of northern Africa and also in Australia, and in southern South America. Coincident with the expansion of the Antarctic ice cap at 14 Ma, there was initial widespread deep sea erosion and changes in patterns of deep sea sedimentation. Muddy pelagic sedimentation increased six-fold in the North and Central Atlantic and Pacific Oceans and global changes in circulation lead to more diatomites in the Pacific and fewer in the Atlantic. By the end of the Miocene most of the Mediterranean Sea had evaporated. Broadly coincident with these events, many old, large river systems were destroyed and new ones formed as much of the world's landscape changed. Collectively, these global on-shore tectonic and ocean-atmospheric events provide the foundation for our modern world—a mixture of new and rejuvenated orogenic belts and their far-field effects (distant epiorogenic uplift, rain-shadow deserts, large alluvial aprons, and distant deltas) as inherited Gondwanan landscapes persisted remote from plate boundaries. Thus at the end of the Miocene much of the world's landscape, except for that changed by Pleistocene continental glaciation, would be recognizable to us today. We argue that all of these events had the same ultimate common cause-an internal Earth engine-that drove plate motions in two broad ways: first, the opening and closing of seven key gateways to deep-water oceanic currents radically altered global heat transfer and changed a lingering Greenhouse to an Icehouse world; secondly, these events were in part coincident with renewed heat flow in the African and Pacific Superplumes that energized global plate motions in the Middle and Upper Miocene. We hope this global synthesis will stimulate more research on the many global events of the Miocene—to understand better both our modern world and earlier global orogenies.

Potter, Paul Edwin; Szatmari, Peter

2009-11-01

116

Antioxidant capacity of polyphenolic extracts from leaves of Crataegus laevigata and Crataegus monogyna (Hawthorn) subjected to drought and cold stress.  

PubMed

Crataegus laevigata and Crataegus monogyna (hawthorn) were subjected to drought and cold stress treatments, and polyphenolic extracts from control and stress-treated plants were assayed for antioxidant capacities using a modified version of the Total Antioxidant Status Assay (Randox, San Francisco, CA). In addition, these plants were analyzed for levels of flavanol-type substance [(-)-epicatechin] and flavonoid (vitexin 2' '-O-rhamnoside, acetylvitexin 2' '-O-rhamnoside, and hyperoside) constituents that are important metabolites in hawthorn herbal preparations used to treat patients with heart disease. Drought and cold stress treatments caused increases in levels of (-)-epicatechin and hyperoside in both Crataegus species. Such treatments also enhanced the antioxidant capacity of the extracts. The results from this study thus indicate that these kinds of stress treatments can enhance the levels of important secondary metabolites and their total antioxidant capacities in leaves of Crataegus. PMID:12822932

Kirakosyan, Ara; Seymour, Elisabeth; Kaufman, Peter B; Warber, Sara; Bolling, Steven; Chang, Soo Chul

2003-07-01

117

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

PubMed

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

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

118

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

PubMed Central

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

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

2012-01-01

119

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

Microsoft Academic Search

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

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

2010-01-01

120

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

PubMed

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

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

2012-01-01

121

New hominoid skull material from the Miocene of Pakistan  

Microsoft Academic Search

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

David Pilbeam

1982-01-01

122

Miocene mass-transport sediments, Troodos Massif, Cyprus  

USGS Publications Warehouse

Sediment mass-transport layers of submarine origin on the northern and southern flanks of the Troodos ophiolitic massif are dated biostratigraphically as early Miocene and late Miocene, respectively and therefore represent different seismogenic events in the uplift and erosional history of the Troodos terrane. Analysis of such events has potential for documenting Miocene seismic and uplift events regionally in the context of changing stress field directions and plate vectors through time. ?? 2009 The Geologists' Association.

Lord, A.R.; Harrison, R.W.; BouDagher-Fadel, M.; Stone, B.D.; Varol, O.

2009-01-01

123

Petrogenesis of the Miocene volcanism along the ?zmir-Bal?kesir Transfer Zone in western Anatolia, Turkey: Implications for origin and evolution of potassic volcanism in post-collisional areas  

NASA Astrophysics Data System (ADS)

The Miocene volcanic rocks along the ?zmir-Bal?kesir Transfer Zone along the western margin of the Menderes Core Complex (MCC) in western Anatolian Volcanic Province (WAVP), where strike-slip deformation is dominant, comprise: (Group 1) early-middle Miocene high-K to shoshonitic rocks with high-Mg# and relatively low SiO2, (Group 2) middle Miocene phonolitic rocks with low-Mg# and intermediate SiO2, (Group 3) early-middle Miocene medium- to high-K series from andesites to rhyolites, (Group 4) middle Miocene rhyolites with distinct trace element compositions; and (Group 5) late Miocene high-MgO basalts, K-trachybasalts and (Group 6) late Miocene high-MgO basaltic andesites. The geochemical features of these rocks are comparable with the other Oligocene to Miocene volcanic rocks, but differ from the Eocene volcanic rocks in WAVP. The geochemical features of the most primitive early-middle Miocene Group 1 rocks indicate that they were derived from an anomalously metasomatized lithospheric mantle. The mineralogical and geochemical properties of garnet-amphibole peridotite from the Ulten Zone (UZP), Eastern Alps, which is thought to represent a fossil metasomatic mantle wedge contaminated by continental subduction, is similar to the model mantle composition previously proposed for the genesis of the mafic rocks. Together with the presence of Eocene to early Miocene continental subduction beneath the Aegean-west Anatolia region, this strongly suggests that continental subduction was an important factor in the genesis of the high-MgO shoshonitic to ultrapotassic volcanism in this post-collisional area. The origin of the Group 3 andesitic to rhyolitic rocks includes; (1) lower crustal melting, (2) mixing between lower crustally-derived and mantle-derived melts, and (3) FC-AFC processes. The late Miocene Group 5 and 6 rocks, however, derived from a more depleted mantle source, indicating that the mantle became depleted over time. The rhyolites of Group 4 are most probably crustally-derived. OIB-type Quaternary Kula volcanics (QKV) were emplaced near the centre of the MCC. Among the late Miocene basalts in the region, only the basalts located close to the QKV show transitional geochemistry between the Miocene volcanic rocks and QKV, indicating that asthenospheric contribution to lavas in the region occurred only near the centre of the MCC.

Ersoy, Yalç?n E.; Helvac?, Cahit; Uysal, ?brahim; Karao?lu, Özgür; Palmer, Martin R.; Dindi, Fulya

2012-10-01

124

Miocene mollusks from the Simojovel area in Chiapas, southwestern Mexico  

NASA Astrophysics Data System (ADS)

The fauna of gastropods and bivalves from the amber-bearing lithostratigraphic units of the Simojovel area, Chiapas is reported, including the description of two new species and one subspecies: Turbinella maya new species, Melongena corona tzeltal new subspecies and Agladrillia ( Eumetadrillia) vermeiji new species. Stratigraphic affinities of the previously described species suggest an Early Miocene age for the Mazantic Shale, and a Middle Miocene age for the overlying Balumtum Sandstone. One specimen of gastropod, with a relatively large piece of amber attached to the adapertural part of the shell is representative for an Early Miocene age and estuarine paleoenvironmental interpretation for the Mazantic Shale. Mollusca, Miocene, Chiapas, Amber, Mexico.

del Carmen Perrilliat, María; Vega, Francisco J.; Coutiño, Marco A.

2010-11-01

125

Hawthorn-infesting populations of Rhagoletis pomonella in Mexico and speciation mode plurality.  

PubMed

Categorizing speciation into dichotomous allopatric versus nonallopatric modes may not always adequately describe the geographic context of divergence for taxa. If some of the genetic changes generating inherent barriers to gene flow between populations evolved in geographic isolation, whereas others arose in sympatry, then the mode of divergence would be mixed. The apple maggot fly, Rhagoletis pomonella, has contributed to this emerging concept of a mixed speciation mode "plurality." Genetic studies have implied that a source of diapause life-history variation associated with inversions and contributing to sympatric host race formation and speciation for R. pomonella in the United States may have introgressed from the Eje Volcanico Trans Mexicano (EVTM; a.k.a. the Altiplano) in the past. A critical unresolved issue concerning the introgression hypothesis is how past gene flow occurred given the current 1200-km disjunction in the ranges of hawthorn-infesting flies in the EVTM region of Mexico and the southern extreme of the U.S. population in Texas. Here, we report the discovery of a hawthorn-infesting population of R. pomonella in the Sierra Madre Oriental Mountains (SMO) of Mexico. Sequence data from 15 nuclear loci and mitochondrial DNA imply that the SMO flies are related to, but still different from, U.S. and EVTM flies. The host affiliations, diapause characteristics, and phylogeography of the SMO population are consistent with it having served as a conduit for gene flow between Mexico and the United States. We also present evidence suggesting greater permeability of collinear versus rearranged regions of the genome to introgression, in accord with recent models of chromosomal speciation. We discuss the implications of the results in the context of speciation mode plurality. We do not argue for abandoning the terms sympatry or allopatry, but caution that categorizing divergence into either/or geographic modes may not describe the genetic origins of all species. For R. pomonella in the United States, the proximate selection pressures triggering race formation and speciation stem from sympatric host shifts. However, some of the phenological variation contributing to host-related ecological adaptation and reproductive isolation in sympatry at the present time appears to have an older history, having originated and become packaged into inversion polymorphism in allopatry. PMID:17492964

Xie, Xianfa; Rull, Juan; Michel, Andrew P; Velez, Sebastian; Forbes, Andrew A; Lobo, Neil F; Aluja, Martin; Feder, Jeffrey L

2007-05-01

126

Highly magnetic Upper Miocene sandstones of the San Francisco Bay area, California  

Microsoft Academic Search

A high-resolution aeromagnetic survey of the San Francisco Bay area shows prominent positive anomalies over distinctive blue sandstones of Late Miocene age. The total-field survey was measured at a nominal height of 300 m above the land surface along flight lines spaced 0.5 km apart. Anomalies with amplitudes up to 200 nT correlate with sandstones of the San Pablo Group,

John W. Hillhouse; Robert C. Jachens

2005-01-01

127

RESEARCH PAPER A Middle Miocene endemic freshwater mollusc assemblage  

E-print Network

lake (Aflenz Basin, Eastern Alps, Austria) Mathias Harzhauser · Thomas A. Neubauer · Oleg Mandic frag- mentation in the Central European freshwater systems during the Early and Middle Miocene of the otherwise African-Medi- terranean genus Bulinus, which is unknown from all other central European Miocene

Zuschin, Martin

128

Middle Miocene tectonic boundary conditions for use in climate models  

E-print Network

is reconstructed through application of an age-depth relationship to a middle Miocene global digital isochron mapMiddle Miocene tectonic boundary conditions for use in climate models N. Herold, M. Seton, and R. D of Marine Science, University of Sydney, Madsen Building F09, Sydney, New South Wales 2006, Australia M

Müller, Dietmar

129

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

E-print Network

in pre­historic times. Study of annual tree­ rings of 12 different petrified trees from the Miocene (or. However, the sunspot cycle is far from regular, with a period ranging from 8 to 14 years (Eddy, 1988 in the Miocene (or Triassic) period. Measurements of the thickness of the annual tree­rings of petrified trees

130

"The most important technique …": Carl Rogers, Hawthorne, and the rise and fall of nondirective interviewing in sociology.  

PubMed

In the 1940s, interviewing practice in sociology became decisively influenced by techniques that had originally been developed by researchers in other disciplines working within a number of therapeutic or quasi-therapeutic contexts, in particular the "nondirective interviewing" methods developed by Carl Rogers and the interviewing procedures developed during the Hawthorne studies. This article discusses the development of nondirective interviewing and looks at how in the 1930s and '40s the approach came to be used in sociology. It examines the factors leading to both the popularity of the method and its subsequent fall from favor. PMID:21462193

Lee, Raymond M

2011-01-01

131

Scale-dependent effects of habitat fragmentation on hawthorn pollination, frugivory, and seed predation.  

PubMed

Habitat fragmentation is a major cause of functional disruption in plant-animal interactions. The net effect on plant regeneration is, however, controversial because a given landscape change can simultaneously hamper mutualism and attenuate antagonism. Furthermore, fragmentation effects may emerge at different spatial scales, depending on the size of the foraging range of the different interacting animals. We studied pollination by insects, frugivory by birds acting as seed dispersers, and postdispersal seed predation by rodents in 60 individual hawthorn (Crataegus monogyna Jacq.) trees in relation to structural fragmentation in the surrounding habitat. We evaluated fragmentation at three spatial scales by measuring the percentage of forest cover in three concentric areas around each tree of, respectively, 10-m, 20- to 50-m, and 50- to 100-m radius. The number of developing pollen tubes per flower style and fruit set decreased in proportion to the decrease of forest cover. Similarly, the magnitude of frugivory in focal trees was negatively affected by habitat loss. In contrast, seed predation was higher under plants in highly fragmented contexts. The effect of fragmentation was additive in terms of reducing the potential of plant regeneration. Moreover, the functional scale of response to habitat loss differed among interactions. Fragmentation effects on pollination emerged at the largest scale, whereas seed predation was mostly affected at the intermediate scale. In contrast to expectations from the larger foraging range of birds, fragmentation effects on frugivory mainly operated at the finest scale, favored by the ability of birds to cope hierarchically with spatial heterogeneity at different scales. Given that two opposing demographic forces (frugivory and seed predation) would be potentially affected by fine-scale features, we propose structural scale as the primary spatial dimension of fragmentation effects on the process of plant regeneration. PMID:17391190

García, Daniel; Chacoff, Natacha P

2007-04-01

132

Phenolic constituents and antioxidant capacities of Crataegus monogyna (Hawthorn) callus extracts.  

PubMed

Crataegus (Hawthorn) has long been used as a folk medicine and is widely utilized in pharmaceutical preparations mainly because of its neuro- and cardiosedative actions and its low toxicity. The pharmacological effects of Crataegus have mainly been attributed to the polyphenolic contents. In this study, the production of polyphenols by ten-year-old Crataegus monogyna calli was studied in relation to growth variation and antioxidant capacity within a subculture period. Assays based on the Trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant power (FRAP) and stability in oil-in-water emulsion were used to characterize the antioxidant actions of the callus cultures. High TEAC (3.66 micromol/g dry weight) and FRAP (208.19 micromol Fe2+/g dry weight) values were observed when maximal growth was reached(days 30-35), and this seemed to be influenced by optimum total phenol (47.40 mg/g dry weight), proanthocyanidin (20.81 mg/g dry weight), flavonoid (7.01 mg/g dry weight), anthocyanin (6.18 mg/g dry weight), (-)-epicatechin (1.77 mgl/g dry weight), procyanidin B2 (3.97 mg/g dry weight), and chlorogenic acid (1.11 mg/g dry weight) production during that period. The TEAC values were strongly associated with total flavonoids and to a lesser extent with total phenols, anthocyanins and total proanthocyanidins. The FRAP antioxidant values correlated to total phenols, proanthocyanidins and flavonoids, respectively. The polyphenolic rich calli were as effective as butylated hydroxytoluene (BHT) in preventing hydroperoxide and conjugated diene formation in a 30% oil-in-water emulsion prepared with stripped sunflower oil, during 7days storage at 30 degrees C. Crataegus monogyna cell culture represents an important alternative source for natural antioxidants. PMID:12866623

Bahorun, Theeshan; Aumjaud, Esha; Ramphul, Hemlata; Rycha, Maheshwaree; Luximon-Ramma, Amitabye; Trotin, Francis; Aruoma, Okezie I

2003-06-01

133

Effect of Temperature on Demographic Parameters of the Hawthorn Red Midget Moth, Phyllonorycter corylifoliella, on Apple  

PubMed Central

The hawthorn red midget moth, Phyllonorycter corylifoliella (Hübner) (Lepidoptera: Gracillariidae), is one of the most serious pests of apple and pear orchards in Iran, however little is known about its biology and relationship with environmental factors. The reproduction and population growth parameters of P. corylifoliella were examined at six constant temperatures (15, 20, 25, 30, 33 and 35° C) on apple var. golden delicious. At 35° C, P. corylifoliella failed to develop beyond the first instar. The lowest (13%) and highest (64%) mortality rates of immature stages occurred at 25 and 33° C, respectively. The life expectancies (ex) decreased with increasing of age and the life expectancies of one-day-old larvae were estimated to be 38.68, 33.34, 35.11, 26.28 and 16.11 days at 15, 20, 25, 30 and 33° C, respectively. The highest intrinsic rate of natural increase (rm), net reproductive rate (Ro) and finite rate of increase (?) at 25° C were 0.100 ± 0.003, 47.66 ± 5.47 and 1.11 ± 0.00, respectively. The mean generation time (T) decreased with increasing temperatures from 86.86 ± 0.53 days at 15° C to 33.48 ± 0.16 days at 30° C. Doubling time (DT) varied significantly with temperature and the shortest doubling time was obtained at 25° C. The results of this study provide direction for future research on evaluating the performance of P. corylifoliella and the efficiency of its natural enemies in apple orchards under variable environmental conditions. PMID:20883137

Amiri, Abbas; Talebi, Ali Asghar; Zamani, Abbas Ali; Kamali, Karim

2010-01-01

134

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

PubMed Central

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

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

2010-01-01

135

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

NASA Astrophysics Data System (ADS)

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.

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

136

Fossil Woodwardia virginica Foliage From the Middle Miocene Yakima Canyon  

NSDL National Science Digital Library

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.

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

2004-03-09

137

Grouping  

NSDL National Science Digital Library

This interactive Flash applet models the measurement interpretation of division. A child or teacher chooses a total number of objects and a divisor representing the size of equal groups. The applet allows the user to move the objects into equal groups and links the process to jumps on a number line. The applet can be used to introduce children to remainders and to reinforce the language and notation of division. It works well on an interactive white board or projector. A teacher's guide to this collection of applets is cataloged separately.

2006-01-01

138

What We Teach Students About the Hawthorne Studies: A Review of Content Within a Sample of Introductory IO and OB Textbooks  

Microsoft Academic Search

The research that took place at a Western Electric Company manufactur- ing plant near Chicago between the years of 1924 and 1933 represents one of the most important historical events in the development of I-O psychology. This body of research, collectively referred to as the Hawthorne Studies (named for the plant in which they took place), was influential in the

Ryan Olson; Jessica Verley; Lindsey Santos; Coresta Salas

139

Miocene reef facies of Pelagian Block, central Mediterranean  

SciTech Connect

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. Substrate, topography, sedimentation rate, and tectonic/eustatic events controlled reef development, which can be grouped into three settings: The most stable situation, the oldest Maltese and southeastern Sicilian reefs, has a ramp profile 15-30 km wide. The outermost zone consists of a broad belt of the large benthic foraminifer Heterostegina (compared with the underyling Oligocene beds rich in Lepidocyclina). Coralline algal carbonates, commonly rhodolitic, form a broad biostromal up-ramp association, kilometers in width, which commonly extends into the shallowest parts of the shelf. Scattered across the shallower ramp areas, in water depths generally less than 10 m, are coral-algal patch reefs, rarely larger than 20-50 m in diameter, commonly with truncated tops, and dominated by crustose coralline algae and the corals Porites and Tarbellastraea.

Pedley, H.M.

1988-01-01

140

Marine Biotic Responses to Miocene Climate Change  

NSDL National Science Digital Library

This activity is part of a collection under development by participants in a June 2006 workshop. Tested versions will be available in Spring 2007. During the Miocene the Earth plunged into its present "icehouse" state, with glaciers at North and South Poles. In this activity, students investigate biotic responses to this climate change using microfossil data from the Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP). These data are analyzed and displayed using the CHRONOS information technology system, building information technology skills while strengthening understanding of biostratigraphic principles. The activity integrates geochemical and biotic data, reinforcing the notion that understanding Earth History requires a multidisciplinary approach. Students use Time Scale Creator to examine how sediments are correlated and dated. DSDP and ODP core data in the Neptune database is used to create age-distribution histograms for foraminifers and calcareous nannofossils, and compare these data to the record of climate change based on oxygen isotope analyses. Students synthesize and compare their discoveries regarding marine microfossil responses to global climate change, and evaluate the assumptions and biases inherent in these results. Step-by-step instructions for using the CHRONOS interface are provided, formatted as a student handout. References to related primary literature are included, and may be used to adapt the exercise for more advanced undergraduates or graduate students.

Ethan Grossman

141

Oligocene-Miocene deformational and depositional history of the Andean hinterland basin in the northern Altiplano plateau, southern Peru  

NASA Astrophysics Data System (ADS)

Cenozoic basin fill of the northern Altiplano plateau records the tectonic development of the flanking Western Cordillera magmatic arc and Eastern Cordillera fold-thrust belt. The Ayaviri hinterland basin of southern Peru contains a ~2300 m thick succession of fluvial sandstones and overbank siltstones (upper Oligocene Puno Group and lower Miocene lower Tinajani Formation) capped by ~400 m of alluvial fan conglomerates (middle Miocene upper Tinajani Formation). New U-Pb zircon chronostratigraphic constraints from ~30 to 15 Ma yield sediment accumulation rates of 110-660 m/Myr. Newly dated growth strata highlight the genetic role played by thrust displacement in basin evolution. A several phase accumulation history derived from chronostratigraphic, provenance, and structural data reveals Oligocene basin filling by fluvial sand and mud that changes provenance from Western Cordillera Mesozoic-Cenozoic volcanic rocks to Paleozoic-Mesozoic Eastern Cordillera sedimentary rocks driven by deformation along the southwest directed, northeastern basin margin Ayaviri thrust at 28-26 Ma. Continued early Miocene fluvial deposition was sourced solely from the Eastern Cordillera. An abrupt middle Miocene shift to coarse alluvial fan deposition sourced from the Western Cordillera was driven by out-of-sequence deformation along the northeast directed, southwestern basin margin Pasani thrust at 18-16 Ma. This northern Altiplano out-of-sequence deformation was coincident with increased Eastern and Western Cordillera exhumation and thrusting and may be symptomatic of changes in critical wedge dynamics. The overall record of basin sedimentation and syndepositional fold-thrust deformation emphasizes the role of regional shortening in governing crustal thickening and basin evolution in the central Andes during the Oligocene to Miocene.

Perez, Nicholas D.; Horton, Brian K.

2014-09-01

142

Miocene sequence biostratigraphy of the northern Gulf of Mexico  

SciTech Connect

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.

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

1993-09-01

143

Modeling geologically abrupt climate changes in the Miocene  

NASA Astrophysics Data System (ADS)

The gradual cooling of the Cenozoic, including the Miocene epoch, was punctuated by many geologically abrupt warming and cooling episodes - strong deviations from the cooling trend with time span of ten to hundred thousands of years. Our working hypothesis is that some of those warming episodes at least partially might have been caused by dynamics of the emerging Antarctic Ice Sheet, which, in turn, might have caused strong changes of sea surface salinity in the Miocene Southern Ocean. Feasibility of this hypothesis is explored in a series of coupled ocean-atmosphere computer experiments. The results suggest that relatively small and geologically short-lived changes in freshwater balance in the Southern Ocean could have significantly contributed to at least two prominent warming episodes in the Miocene. Importantly, the experiments also suggest that the Southern Ocean was more sensitive to the salinity changes in the Miocene than today, which can attributed to the opening of the Central American Isthmus as a major difference between the Miocene and the present-day ocean-sea geometry.

Haupt, B. J.; Seidov, D.

2010-12-01

144

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

PubMed Central

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

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

2014-01-01

145

Late Miocene “washhouse” climate in Europe  

NASA Astrophysics Data System (ADS)

We present two eight-million year long proxy records of precipitation for Southwest and Central Europe, covering the middle to late Miocene (5.3-13 Ma) at a temporal resolution of about 60 kyr and 150 kyr, respectively. The estimates of precipitation are based on the ecophysiological structure of herpetological assemblages (amphibians and reptiles). From 13.0 Ma until about 9 Ma, both records show a similar trend, evolving from a long dry period (13-11 Ma) into a "washhouse climate" (10.2-9.8 Ma), characterized by global warm conditions and several times more precipitation than present. The transition from washhouse to a dryer climate between 9.7 and 9.5 Ma and the concomitant cooling episode appear to have triggered a severe biotic event known as the Vallesian crisis, which included the extinction of hominoids in Western Europe. A second washhouse period (9.0-8.5 Ma), coeval with a global warm episode, was unprecedentedly intense in Southwest Europe, but less pronounced in Central Europe. From 8 Ma onward, a divergence in the two precipitation records is observed, with Southwest Europe staying wetter and Central Europe becoming dryer than present. Both precipitation records are combined into a common run-off curve as a measure of the relative intensity of the hydrological cycle for moderate latitudes of continental Europe. The run-off curve shows a remarkable positive correlation with Atlantic deep-water temperatures from Ceará Rise by Lear et al. (2003), which are significantly higher (up to + 3 °C) during the two washhouse periods and show no other positive excursion of comparable magnitude. We discuss potential links and the role of the coeval temporary restriction of the Central American Seaway on ocean and atmosphere circulation.

Böhme, Madelaine; Ilg, August; Winklhofer, Michael

2008-11-01

146

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

PubMed

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

Tesakov, A S; Lopatin, A V

2015-01-01

147

Characterization of Miocene-Pliocene carbonate platforms, southern Southwest Palawan Basin, Philippines  

E-print Network

Isolated carbonate platforms and buildups of the Likas Formation provide a long record of carbonate sedimentation in the southern end of the Southwest Palawan Basin. While most carbonate platforms terminated in early Miocene and middle Miocene time...

Sta. Ana, Ma. Corazon Victor

2009-06-02

148

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

E-print Network

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 ...

Robertson, Alastair H F

1998-01-01

149

Middle Miocene closure of the Central American Seaway.  

PubMed

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. PMID:25859042

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

2015-04-10

150

On the Miocene Cyprideis species flock (Ostracoda; Crustacea) of Western Amazonia (Solimões Formation): Refining taxonomy on species level.  

PubMed

The Miocene mega-wetland of western Amazonia holds a diverse, largely endemic ostracod fauna. Among them, especially 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. We evaluate the diagnostic value of shell characters and provide an extensive illustration of the intraspecific variability of species. Based on comparative morphology, the 20 recorded Cyprideis species are arranged in groups and subgroups. The "smooth" group comprises C. amazonica, C. kotzianae, C. kroemmelbeini, C. machadoi, C. multiradiata, C. olivencai, C. paralela and C. simplex; the "ornate" group C. curucae nom. nov., C. cyrtoma, C. aff. graciosa, C. inversa, C. ituiae n. sp., C. matorae n. sp., C. minipunctata, C. munoztorresi nom. nov., C. pebasae, C. reticulopunctata, C. schedogymnos and C. sulcosigmoidalis. Five species have been revalidated, two renamed, two synonymised and two are new descriptions. Along with 10 further formally established species, for which a review is pending, Cyprideis keeps at least 30 endemic species in that region during Miocene times. Up to 12 Cyprideis species have been found to occur sympatrically, representing >90 % of the entire ostracod fauna. Ostracod index species enable a biostratigraphic allocation of the well succession to the Cyprideis minipunctata to Cyprideis cyrtoma biozones, corresponding to a late Middle to early Late Miocene age (late Serravallian-early Tortonian).  PMID:25543674

Gross, Martin; Ramos, Maria Ines F; Piller, Werner E

2014-01-01

151

Interpretation of Samburupithecus, an upper Miocene hominoid from Kenya  

NASA Astrophysics Data System (ADS)

Samburupithecus, an extinct great ape from upper Miocene (9.5 Ma) deposits in Kenya, is compared with other fossil and extant hominoids. It possesses features which are derived in comparison with Proconsul and other Lower and Middle Miocene hominoids, but it has none of the derived features which characterize the Eurasian large apes. It possesses characters which indicate that its closest relationships lie with the AAH clade (extant African apes and man). Within this clade it is closest dentally to primitive hominids such as Praeanthropus.

Pickford, Martin; Ishida, Hidemi

1998-02-01

152

Middle Miocene tectonic boundary conditions for use in climate models  

NASA Astrophysics Data System (ADS)

Utilizing general circulation models (GCMs) for paleoclimate study requires the construction of appropriate model boundary conditions. We present a middle Miocene paleotopographic and paleobathymetric reconstruction geographically constrained at 15 Ma for use in GCMs. Paleotopography and paleogeography are reconstructed using a published global plate rotation model and published geological data. Paleobathymetry is reconstructed through application of an age-depth relationship to a middle Miocene global digital isochron map, followed by the overlay of reconstructed sediment thickness and large igneous provinces. Adjustments are subsequently made to ensure our reconstruction may be utilized in GCMs.

Herold, N.; Seton, M.; Müller, R. D.; You, Y.; Huber, M.

2008-10-01

153

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

USGS Publications Warehouse

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.

Drobniak, A.; Mastalerz, M.

2006-01-01

154

Highly magnetic Upper Miocene sandstones of the San Francisco Bay area, California  

NASA Astrophysics Data System (ADS)

A high-resolution aeromagnetic survey of the San Francisco Bay area shows prominent positive anomalies over distinctive blue sandstones of Late Miocene age. The total-field survey was measured at a nominal height of 300 m above the land surface along flight lines spaced 0.5 km apart. Anomalies with amplitudes up to 200 nT correlate with sandstones of the San Pablo Group, and these anomalies are similar in strength to the magnetic signatures of serpentinites and basalts in the surveyed region. Andesitic sandstone of the Neroly Formation, the upper part of the San Pablo Group, has high magnetic susceptibility (0.013 SI units, volume) and relatively strong natural remanent magnetization (0.29 A/m). Total magnetization of the sandstone is two thirds induced and one third remanent magnetization. The presence of coarse-grained magnetite detritus, low coercivity of remanence, low thermal stability of remanence, and multidomain properties is consistent with the NRM being a viscous remanent magnetization that grew during the Brunhes normal-polarity chron. The strong magnetic signature of the Upper Miocene sandstones allows their delineation over distances as great as 100 km, through areas where they are concealed by landslides and younger deposits. The sandstones are important structural markers for understanding the complex folding and faulting associated with active fault systems in the San Francisco Bay area.

Hillhouse, John W.; Jachens, Robert C.

2005-05-01

155

Occlusal Enamel Complexity in Middle Miocene to Holocene Equids (Equidae: Perissodactyla) of North America  

PubMed Central

Four groups of equids, “Anchitheriinae,” Merychippine-grade Equinae, Hipparionini, and Equini, coexisted in the middle Miocene, but only the Equini remains after 16 Myr of evolution and extinction. Each group is distinct in its occlusal enamel pattern. These patterns have been compared qualitatively but rarely quantitatively. The processes influencing the evolution of these occlusal patterns have not been thoroughly investigated with respect to phylogeny, tooth position, and climate through geologic time. We investigated Occlusal Enamel Index, a quantitative method for the analysis of the complexity of occlusal patterns. We used analyses of variance and an analysis of co-variance to test whether equid teeth increase resistive cutting area for food processing during mastication, as expressed in occlusal enamel complexity, in response to increased abrasion in their diet. Results suggest that occlusal enamel complexity was influenced by climate, phylogeny, and tooth position through time. Occlusal enamel complexity in middle Miocene to Modern horses increased as the animals experienced increased tooth abrasion and a cooling climate. PMID:24587267

Famoso, Nicholas A.; Davis, Edward Byrd

2014-01-01

156

Occlusal enamel complexity in middle miocene to holocene equids (Equidae: Perissodactyla) of North America.  

PubMed

Four groups of equids, "Anchitheriinae," Merychippine-grade Equinae, Hipparionini, and Equini, coexisted in the middle Miocene, but only the Equini remains after 16 Myr of evolution and extinction. Each group is distinct in its occlusal enamel pattern. These patterns have been compared qualitatively but rarely quantitatively. The processes influencing the evolution of these occlusal patterns have not been thoroughly investigated with respect to phylogeny, tooth position, and climate through geologic time. We investigated Occlusal Enamel Index, a quantitative method for the analysis of the complexity of occlusal patterns. We used analyses of variance and an analysis of co-variance to test whether equid teeth increase resistive cutting area for food processing during mastication, as expressed in occlusal enamel complexity, in response to increased abrasion in their diet. Results suggest that occlusal enamel complexity was influenced by climate, phylogeny, and tooth position through time. Occlusal enamel complexity in middle Miocene to Modern horses increased as the animals experienced increased tooth abrasion and a cooling climate. PMID:24587267

Famoso, Nicholas A; Davis, Edward Byrd

2014-01-01

157

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

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

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

1996-01-01

158

Tectonic implications of early Miocene volcanic rocks, San Joaquin basin  

Microsoft Academic Search

The early Miocene (22 Ma) Tecuya volcanic rocks of the San Emigdio Mountains were erupted during a regional episode of crustal extension in coastal California. These rocks are correlative with similar rocks in outcrops and the subsurface over at least 800 kmz in the southern San Joaquin basin. Initial dacitic eruptions produced laterally continuous subaerial to submarine pyroclastic flows. These

R. B. Cole; P. G. Decelles

1990-01-01

159

RESEARCH PAPER Stable isotope ecology of Miocene large mammals  

E-print Network

pattern of seasonality. Thus most taxa were C3 browsers in a forested and humid floodplain environmentRESEARCH PAPER Stable isotope ecology of Miocene large mammals from Sandelzhausen, southern Germany (Chalicotheriidae) and P. germanicus (Rhinocerotidae) were browsers in more closed forest environments. The horse

Schöne, Bernd R.

160

Miocene Slab Detachment in Central Mexico: Causes and Consequences  

Microsoft Academic Search

I propose that the lower part of the Farallon slab subducted beneath Mexico has detached twice during the Miocene. Initiation of slab detachment is a consequence of the incoming of increasingly buoyant oceanic crust at the paleotrench off Baja California and, eventually, the capture by the Pacific plate of the microplates left over by the Farallon plate that produced a

L. Ferrari

2002-01-01

161

Published online 7 October 2004 Multiple Miocene Melastomataceae dispersal  

E-print Network

Published online 7 October 2004 Multiple Miocene Melastomataceae dispersal between Madagascar Strasse 67, D-80638 Munich, Germany (renner@lrz.uni-muenchen.de) Melastomataceae sensu stricto (excluding. An alternative hypothesis posits that the ancestors of Madagascan, as well as Indian, Melastomataceae arrived

Renner, Susanne

162

Provenance study conflict Miocene eolian deposit in central China  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

163

The early to mid-Miocene environment of Antarctica  

NASA Astrophysics Data System (ADS)

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.

Ashworth, A. C.; Lewis, A.

2012-12-01

164

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

USGS Publications Warehouse

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.

Alan, Bartow J.

1990-01-01

165

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

NASA Astrophysics Data System (ADS)

The emergence of C4 photosynthesis in plants as a significant component of terrestrial ecosystems is thought to be an adaptive response to changes in atmospheric CO 2 concentration and/or climate during Neogene times and has had a profound effect on the global terrestrial biosphere. Although expansion of C4 grasses in the latest Miocene and Pliocene has been widely documented around the world, the spatial and temporal variations in the C4 expansion are still not well understood and its driving mechanisms remain a contentious issue. Here we present the results of carbon and oxygen isotope analyses of fossil and modern mammalian tooth enamel samples from the central Inner Mongolia. Our samples represent a diverse group of herbivorous mammals including deer, elephants, rhinos, horses and giraffes, ranging in age from the late Oligocene to modern. The ?13C values of 91 tooth enamel samples of early late-Miocene age or older, with the exception of two 13 Ma rhino samples (- 7.8 and - 7.6‰) and one 8.5 Ma suspected rhino sample (- 7.6‰), were all less than - 8.0‰ (VPDB), indicating that there were no C4 grasses present in their diets and thus probably few or no C4 grasses in the ecosystems of the central Inner Mongolia prior to ~ 8 Ma. However, 12 out of 26 tooth enamel samples of younger ages (~ 7.5 Ma to ~ 3.9 Ma) have ?13C values higher than - 8.0‰ (up to - 2.4‰), indicating that herbivores in the area had variable diets ranging from pure C3 to mixed C3-C4 vegetation during that time interval. The presence of C4 grasses in herbivores' diets (up to ~ 76% C4) suggests that C4 grasses were a significant component of the local ecosystems in the latest Miocene and early Pliocene, consistent with the hypothesis of a global factor as the driving mechanism of the late Miocene C4 expansion. Today, C3 grasses dominate grasslands in the central Inner Mongolia area. The retreat of C4 grasses from this area after the early Pliocene may have been driven by regional climate change associated with tectonic processes in central Asia as well as global climate change.

Zhang, Chunfu; Wang, Yang; Deng, Tao; Wang, Xiaoming; Biasatti, Dana; Xu, Yingfeng; Li, Qiang

2009-10-01

166

A new pitheciin primate from the middle Miocene of Argentina.  

PubMed

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

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

1998-01-01

167

A study of uranium favorability of Cenozoic sedimentary rocks, Basin and Range Province, Arizona: Part I, General geology and chronology of pre-late Miocene Cenozoic sedimentary rocks  

USGS Publications Warehouse

This study focuses attention on Cenozoic sedimentary rocks in the Basin and Range Province of Arizona. The known occurrences of uranium and anomalous radioactivity in these rocks are associated with sediments that accumulated in a low energy environment characterized by fine-grained clastics, including important tuffaceous materials, and carbonate rocks. Most uranium occurrences, in these rocks appear to be stratabound. Emphasis was placed on those sedimentary materials that pre-date the late Cenozoic Basin and Range disturbance. They are deformed and crop out on pedimented range blocks and along the province interface with the Transition Zone. Three tentative age groups are recognized: Group I - Oligocene, pre-22 m.y., Group II - early Miocene - 22 m.y. - 16 m.y., and Group III - middle Miocene - 16 m.y. to 13--10 m.y. Regionally, these three groups contain both coarse to fine-grained red clastics and low energy lighter colored 'lacustrine' phases. Each of the three groups has been the object of uranium exploration. Group II, the early Miocene strata, embraces the Anderson Mine - Artillery region host rocks and also the New River - Cave Creek early Miocene beds-along the boundary with the Transition Zone. These three groups of rocks have been tectonically deformed to the extent that original basins of deposition cannot yet be reconstructed. However, they were considerably more extensive in size than the late Cenozoic basins the origin of which deformed the former. Group II rocks are judged to be of prime interest because of: (1) the development and preservation of organic matter in varying lithologies, (2) apparent contemporaneity with silicic volcanic centers, (3) influence of Precambrian crystalline rocks, and (4) relative outcrop continuity near the stable Transition Zone. The Transition Zone, especially along its boundary with the Basin and Range Province, needs additional geologic investigation, especially as regards the depositional continuity of Group II sediment s.

Scarborough, Robert Bryan; Wilt, Jan Carol

1979-01-01

168

First Hominoid from the Late Miocene of the Irrawaddy Formation (Myanmar)  

PubMed Central

For over a century, a Neogene fossil mammal fauna has been known in the Irrawaddy Formation in central Myanmar. Unfortunately, the lack of accurately located fossiliferous sites and the absence of hominoid fossils have impeded paleontological studies. Here we describe the first hominoid found in Myanmar together with a Hipparion (s.l.) associated mammal fauna from Irrawaddy Formation deposits dated between 10.4 and 8.8 Ma by biochronology and magnetostratigraphy. This hominoid documents a new species of Khoratpithecus, increasing thereby the Miocene diversity of southern Asian hominoids. The composition of the associated fauna as well as stable isotope data on Hipparion (s.l.) indicate that it inhabited an evergreen forest in a C3-plant environment. Our results enlighten that late Miocene hominoids were more regionally diversified than other large mammals, pointing towards regionally-bounded evolution of the representatives of this group in Southeast Asia. The Irrawaddy Formation, with its extensive outcrops and long temporal range, has a great potential for improving our knowledge of hominoid evolution in Asia. PMID:21533131

Jaeger, Jean-Jacques; Naing Soe, Aung; Chavasseau, Olivier; Coster, Pauline; Emonet, Edouard-Georges; Guy, Franck; Lebrun, Renaud; Maung, Aye; Aung Khyaw, Aung; Shwe, Hla; Thura Tun, Soe; Linn Oo, Kyaw; Rugbumrung, Mana; Bocherens, Hervé; Benammi, Mouloud; Chaivanich, Kamol; Tafforeau, Paul; Chaimanee, Yaowalak

2011-01-01

169

Mid Miocene Terrestrial Ecosystems: Information from Mammalian Herbivore Communities.  

NASA Astrophysics Data System (ADS)

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.

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

2001-05-01

170

Late Miocene biogeography and paleoclimatology of the central North Atlantic  

USGS Publications Warehouse

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.

Poore, R.Z.

1981-01-01

171

Upper Miocene reef complex of Mallorca, Balearic Islands, Spain  

SciTech Connect

The late Tortonian-Messinian coral reef platform of south Mallorca onlaps a folded middle late Miocene carbonate platform on which progradation of up to 20 km occurs. Vertical sea cliffs (up to 100 m high) superbly show the last 5 km of this progradation and complement the numerous water-well cores from the island interior. The Mallorca reef presents the most complete facies zonation of the Miocene reefs of the western Mediterranean. The reef wall framework is up to 20 m thick and shows (1) erosional reef flat with reef breccia and small corals; (2) spur-and-grove zone with large, massive corals; (3) deep buttresses and pinnacles with terraces of branching corals; and (4) deep reef wall with flat, laminar coral colonies, branching red algae, and Halimeda sands.

Pomar, L.

1988-02-01

172

Miocene isotope chronostratigraphy: North-central Gulf of Mexico  

Microsoft Academic Search

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

D. M. Trainor; D. F. Williams

1991-01-01

173

Diagenesis of Miocene arkoses of the southern San Joaquin Valley  

E-print Network

noted that montmorillonite was a ccmnon authigenic product Further- more, Kleinpell (1938) noted that volcanic ectivity occured in the area bordering the southern San Joaquin basin sll during tne Miocene; it is conceivable that there was volcanic ash... resulting from dlsgenesis : ?;egional geology of Southern San Joaquin ya le~ tee southern S~. goaquin yalle~ of California 's bound d . ,n thc west 'oy the San Andreas fault and associated folds, on the ass+ the Sierra . ;evade. Uplift, and on tl e...

Brasher, James Everett

1982-01-01

174

Preservation of Miocene glacier ice in East Antarctica  

Microsoft Academic Search

ANTARCTIC climate during the Pliocene has been the subject of considerable debate. One view holds that, during part of the Pliocene, East Antarctica was largely free of glacier ice and that vegetation survived on the coastal mountains1á¤-4. An alternative viewpoint argues for the development of a stable polar ice sheet by the middle Miocene, which has persisted since then5á¤-10. Here

David E. Sugden; David R. Marchant; Noel Potter; Roland A. Souchez; George H. Denton; Carl C. Swisher III; Jean-Louis Tison

1995-01-01

175

Across the Pacific: Climate Evolution in the Middle Miocene  

NASA Astrophysics Data System (ADS)

We present the first high-resolution (3 kyr) astronomically-tuned record of ?18O and ?13C from planktonic foraminifera for the equatorial Pacific Ocean (16.5-13.5 Myr). Our data provides exciting new information on sea surface temperatures and primary productivity changes at the tropics during the middle Miocene at a resolution not achieved in any previous study, which sheds new light on the middle Miocene climatic transition (MMCT) and associated carbon-isotope excursion. Reliable sea surface temperature estimates are crucial to any reconstruction and modelling of past ocean salinity and density, water column stratification, thermohaline circulation, and ice volume. Despite extensive studies of benthic foraminifera, existing planktonic foraminiferal records of this interval are extremely scarce and of low resolution, with samples representing time intervals of 2x105 and 5x105 years. Previous studies have been hindered by the absence of biogenic carbonate (e.g., Leg 199). Consequently the impact of global warming and cooling on tropical surface waters and the propagation of orbital cycles in the Earth System are unknown. In 2009 Integrated Ocean Drilling Program Expedition 320/321 recovered lower-middle Miocene sediments with high sedimentation rates (30m/myr), continuous recovery, and orbital cyclicity from the east equatorial Pacific Ocean. At Site U1338 planktonic foraminifera are abundant and diverse in the lower and middle Miocene sediments and exceptionally well preserved. Scanning electron microscope studies revealed open pore spaces, little evidence of calcitic overgrowth on the wall surface and in many cases preserved spines (Fox and Wade, in press). We compare our data from Site U1338 to Site 1146 in the western equatorial Pacific Ocean, to reconstruct bottom and surface water conditions and changes in ocean dynamics across the equatorial Pacific during this highly complex interval of climate history.

Fox, L. R.; Wade, B.; Holbourn, A. E.; Leng, M. J.

2013-12-01

176

Across the Pacific: Climate Evolution in the Middle Miocene  

NASA Astrophysics Data System (ADS)

We present the first high-resolution (3 kyr) astronomically-tuned record of ?18O and ?13C from planktonic foraminifera for the equatorial Pacific Ocean (16.5-13.5 Myr). Our data provides exciting new information on sea surface temperatures and primary productivity changes at the tropics during the middle Miocene at a resolution not achieved in any previous study, which sheds new light on the middle Miocene climatic transition (MMCT) and associated carbon-isotope excursion. Reliable sea surface temperature estimates are crucial to any reconstruction and modelling of past ocean salinity and density, water column stratification, thermohaline circulation, and ice volume. Despite extensive studies of benthic foraminifera, existing planktonic foraminiferal records of this interval are extremely scarce and of low resolution, with samples representing time intervals of 2x105and 5x105 years. Previous studies have been hindered by the absence of biogenic carbonate (e.g., Leg 199). Consequently the impact of global warming and cooling on tropical surface waters and the propagation of orbital cycles in the Earth System are unknown. In 2009 Integrated Ocean Drilling Program Expedition 320/321 recovered lower-middle Miocene sediments with high sedimentation rates (30m/myr), continuous recovery, and orbital cyclicity from the east equatorial Pacific Ocean. At Site U1338 planktonic foraminifera are abundant and diverse in the lower and middle Miocene sediments and exceptionally well preserved. Scanning electron microscope studies revealed open pore spaces, little evidence of calcitic overgrowth on the wall surface and in many cases preserved spines (Fox and Wade, 2013). We compare our data from Site U1338 to Site 1146 in the western equatorial Pacific Ocean, to reconstruct bottom and surface water conditions and changes in ocean dynamics across the equatorial Pacific during this highly complex interval of climate history.

Fox, Lyndsey; Wade, Bridget; Holbourn, Ann; Leng, Melanie

2014-05-01

177

North Atlantic Deep Water formed by the later middle Miocene  

Microsoft Academic Search

There is evidence that in Mesozoic and Palaeogene times both north and south subpolar areas had a mild climate1,2. Unlike the present day climatic symmetry, with warm equatorial regions and ice-covered polar regions, a strong planetary asymmetry developed in the middle Miocene, when the Antarctic ice cap was established while the northern high latitudes remained unglaciated3. The symmetry was restored

P.-L. Blanc; D. Rabussier; C. Vergnaud-Grazzini; J.-C. Duplessy

1980-01-01

178

Human evolution from the Miocene to the Present  

Microsoft Academic Search

Based on morphological, palaeoanthropological and molecular biological studies, human evolution from the Miocene to the Present\\u000a has been reviewed. The initial divergence of orangutan from the hominoid stock, the divergence of man from the last common\\u000a ancestor with the African apes, the origin and expansion ofHomo lineage and the advent of modern man have been discussed.

Shama Barnabas

1990-01-01

179

Early Miocene rodents and insectivores from northeastern Colorado  

E-print Network

THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS VE RTE B RATA ARTICLE 7 Pages 1-92, Figures 1-131 EARLY MIOCENE RODENTS AND INSECTIVORES FROM NORTHEASTERN COLORADO By ROBERT W. WILSON ARTICLE 8 Pages 1-24, Figures 1-21 A NEW ARMORED DINOSAUR... AND INSECTIVORES FROM NORTHEASTERN COLORADO By ROBERT W. WILSON (Contribution from the Museum of Natural History) THE UNIVERSITY OF KANSAS PUBLICATIONS November 21, 1960 PRINTED BY THE UNIVERSITY OF KANSAS PRESS LAWRENCE THE UNIVERSITY OF KANSAS PALEONTOLOGICAL...

Wilson, R. W.

1960-11-21

180

Miocene phreatomagmatic volcanism at Tihany (Pannonian Basin, Hungary)  

Microsoft Academic Search

A late Miocene (7.56Ma) maar volcanic complex (Tihany Maar Volcanic Complex — TMVC) is preserved in the Pannonian Basin and is part of the Bakony–Balaton Highland Volcanic Field. Base surge and fallout deposits were formed around maars by phreatomagmatic explosions, caused by interactions between water-saturated sediments and alkali basalt magma carrying peridotite lherzolite xenoliths as well as pyroxene and olivine

K. Németh; U Martin; Sz Harangi

2001-01-01

181

Oligo-Miocene syn-rift and Miocene post-rift sedimentary records: the tectono-stratigraphic development of the northern proximal margin of the Gulf of Aden  

NASA Astrophysics Data System (ADS)

The northern margin of the Gulf of Aden results from the Oligo-Miocene rifting (34Ma) leading to continental break-up and the oceanic spreading since the Burdigalian (17.6 Ma). We, here, investigate in detail the tectono-stratigraphy development of the Ashawq Graben belonging to the proximal part of northern margin (southern Oman, Dhofar). This graben exhibits sedimentary records of syn-rift and post-rift sequences, so-called Dhofar (Rupelian-Burdigalian) and Fars (middle Miocene-Pliocene) Groups respectively. Analyzing the deposit conditions and sequences geometries provide fundamental inputs for the whole margin understanding. An accurate sedimentological and biostratigraphical analysis evidences two second-order sea level cycles corresponding to the syn-rift and the post-rift units separated by an erosive surface with paleo-karst cavities. The first stage of the rifting expresses as a regional uplift which led to set up of an early Oligocene mix platform system (Ashawq Fm., Shizar Mb.) overlying the proximal platform (Aydim Fm.) and continental (Zalumah Fm.) system deposit of the late Eocene to earliest Oligocene time. Then, the rift extension process during early Oligocene leads to verticals movements along normal faults and increase of the accommodation rate in the Ashawq graben. Such increase of accommodation is fully compensated by an important carbonate production leading to the aggradation of a thick reefal carbonate platform (Ashawq Fm., Nakhlit Mb.). An acceleration of the extension processes during late Oligocene time reaches an increase of the tectonic subsidence associated to the partial drowning and collapsing of the platform and to the set up of carbonate gravity-flow deposits in a deep basin (Mughsayl Fm.). In the most proximal realm, the sedimentation rate attempts to compensate the accommodation rate resulting in a differential aggradation of the reefal carbonate platform, sometimes in the form of patch reef. At the early Miocene time, the progradation of a conglomeratic fan delta system testifies the decrease of the accommodation rate and a strong basinward system shift controlled by a general uplift of the margin. This surrection phase leading to a subaerial exposure is interpreted as the consequence of the continental breakup at the Burdigalian time (17.6 Ma) and the set up of Ocean-Continent Transition (OCT). At the middle Miocene time, new subsidence phase is associated with a partial marine incursion and to the set up of proximal shallow marine carbonate deposits (Adawnib Fm.) and the lateral equivalent conglomeratic alluvial fan deposits (Nar Fm.). This post-rift unit records a progressive decrease of the tectonic activity, which may be related to the migration of the deformation towards the distal margin up to the oceanic spreading in the Gulf of Aden. Late deformation phases (erosive paleo-surface at the top the post-rift conglomerates, preservation of uplifted paleo-beach deposits) may imply a large-scale geodynamic processes.

Robinet, J.; Razin, P.; Serra Kiel, J.; Gallardo Garcia, A.; Grelaud, C.; Roger, J.; Leroy, S.; Malaval, M.

2012-04-01

182

12. STRONTIUM-ISOTOPIC CORRELATION OF OLIGOCENE TO MIOCENE SEQUENCES, NEW JERSEY AND FLORIDA1  

Microsoft Academic Search

We use Sr-isotopic age estimates to date siliciclastic, carbonate, and mixed siliciclastic-carbonate Oligocene and Miocene sequences for the New Jersey Coastal Plain and Florida Peninsula and to correlate sequence boundaries with the deep-sea ?18O record and the inferred eustatic record of Exxon. The New Jersey onshore Oligocene to lower Miocene sequences correlate rea- sonably well with the Florida Miocene sequences.

Peter J. Sugarman; Lucy McCartan; Kenneth G. Miller; Mark D. Feigenson; Stephen Pekar; Ronald W. Kistler; A. G. Robinson

183

Middle Miocene paleoaltimetry of the southern Altiplano, central Andes  

NASA Astrophysics Data System (ADS)

The central Andean plateau is both high (mean elevation ~4 km) and broad (>300 km wide). Constraining the elevation history of the Andes is necessary to understand the effects of a high, broad mountain range on regional and global climate and the tectonic processes responsible for the creation and maintenance of such mountain plateaus. Recent paleoelevation estimates based on paleobotanical, stable isotope, and geomorphologic data suggest that the northern part of the central Andes experienced ~2.5 ± 1 km of surface uplift since ca. 10 Ma. Middle Miocene sedimentary sections were measured in two localities in the southern Altiplano and Eastern Cordillera. The depositional environment of Cerdas (~4000 m, ~16.3 to <15.105 Ma) in the Altiplano basin was dominantly fluvial floodplain and volcaniclastic-rich gravity flows; Quebrada Honda (~3500 m, >12.83 to <11.96 Ma) in the Eastern Cordillera consists of fluvial floodplain and ephemeral lacustrine environments. Sedimentation rates are on the order of 100-200 m/Myr, which is comparable to other middle Miocene basins in the central Andes. Carbonate nodules from paleosols within floodplain deposits were analyzed for stable isotopes. We employ a ?18O-altitude relationship based on modern rainfall (Gonfiantini et al., 2001) and surface water data to estimate paleoelevation from pedogenic carbonates. Data from Cerdas yield a mean ?18O of -10.8‰ and a paleoelevation estimate of 2458 ± 1000 m; data from Quebrada Honda produce a mean of -7.2‰ and a paleoelevation estimate of 757 ± 1000 m. These low elevations (relative to the modern elevations) in the southern Altiplano are consistent (within error) with published middle Miocene elevations for the northern Altiplano, suggesting a common plateau-wide elevation history prior to <11.96 Ma. If changes in paleoelevation of the southern Altiplano show synchronous late Miocene surface uplift as compared with the northern Altiplano, this would suggest that a regional tectonic process was responsible for the ~2 km of surface uplift since middle Miocene time.

Auerbach, D. J.; Garzione, C. N.; Smith, J. J.; MacFadden, B. J.

2008-12-01

184

Miocene West Directed Back Thrusting in the Southeast Pamir, China  

NASA Astrophysics Data System (ADS)

A critical component of understanding the evolution of orogenic belts is the spatial and temporal distribution of deformation. In the Pamir at the western end of the Indo-Asian collision zone, Cenozoic deformation has been dominated by Oligocene to Recent shortening and strike-slip deformation along the margins of the Pamir salient, with the interior of the Pamir dominated by Miocene to Recent gneiss dome formation and east-west extension. While Cenozoic internal shortening has been inferred within the Central and Southern Pamir terranes, it remains unclear how much of that deformation may be older (i.e. Cretaceous) in age. The lack of significant documented Cenozoic internal shortening within the Pamir presents a problem in understanding the evolution of Oligocene to Late Miocene internal crustal thickening documented in the northeast Pamir in the footwall of the Kongur Shan extensional system. Along the Tashkorgan Valley in the Southeastern Pamir, upper greenschist to amphibolite facies schists overly lower greenschist facies marbles and shales along a northeast dipping thrust fault. Kinematic indicators including stretching lineations, rotated porphyroblasts, and S-C fabrics show consistent top-to-the W to NW sense of shear. This thrust fault was previously interpreted to be Cretaceous in age based on correlation with the west-directed Torbashi thrust exposed to the north, which juxtaposes upper amphibolite facies schists with Cretaceous mica cooling ages over lower greenschist facies metavolcanics and schists. Two pieces of evidence suggest either Middle-Miocene reactivation along the southern trace of the fault, or formation of a new structure: 1) A biotite 40Ar/39Ar analysis from the hanging wall of the thrust yields an age of 14.87±0.04 Ma, and 2) In-situ Th-Pb matrix monazite ages from a biotite-garnet schist with syn-tectonic garnets in the immediate hanging wall of the thrust yield an age of 14.6±0.9 Ma interpreted to date peak metamorphic conditions in the schist. These results suggest the development of a regional, west-directed back-thrust along the southeast margin of the Pamir in the Middle Miocene which we call the Dabudaer thrust. This thrust may have developed in part due to transpressive deformation along the eastern margin of the Pamir. Additionally, the documentation of significant Miocene shortening and thrust exhumation in the southeast Pamir provides a possible mechanism to help drive Late Cenozoic internal thickening in the Central and Northern Pamir. We suggest the thrust may be kinematically linked with the inferred Eastern Pamir Shear zone of Robinson et al. (2004).

Robinson, A. C.; Imrecke, D. B.; Heizler, M. T.; Chen, J.; Wenqiao, L.; Yang, X.; Yuan, Z.

2010-12-01

185

A new solid-phase extraction and HPLC method for determination of patulin in apple products and hawthorn juice in China.  

PubMed

A new solid-phase extraction (SPE) pretreatment method using a home-made polyvinylpolypyrrolidone-florisil (PVPP-F) column was developed for the analysis of patulin in apple and hawthorn products in China. Fifty samples (25 apple juices, 12 apple jams, and 13 hawthorn juices) were prepared using the new method and then analyzed by high performance liquid chromatography with diode array detection (HPLC-DAD) on an Agela Venusil MP C(18) reversed-phase column (4.6 mm × 250 mm, 5 ?m). The cleanup results for all samples using home-made PVPP-F column were compared with those obtained using a MycoSep®228 AflaPat column. The correlation coefficient R (0.9998) fulfilled the requirement of linearity for patulin in the concentration range of 2.5-250 ?g/kg. The limits of detection (LODs) and quantification (LOQs) of patulin were 3.99 and 9.64 ?g/kg for PVPP-F column, and 3.56 and 8.07 ?g/kg for MycoSep®228 AflaPat column, respectively. Samples were spiked with patulin at levels ranging from 25 to 250 ?g/kg, and recoveries using PVPP-F and MycoSep®228 AflaPat columns were in the range of 81.9-100.9% and 86.4-103.9%, respectively. Naturally occurring patulin was found in 2 of 25 apple juice samples (8.0%) and 1 of 13 hawthorn juice samples (7.7%) at concentrations ranging from 12.26 to 36.81 ?g/kg. The positive results were further confirmed by liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS). PMID:22517639

Zhou, Yuchun; Kong, Weijun; Li, Yan; Logrieco, Antonio F; Xu, Jun; Yang, Meihua

2012-03-01

186

The genus Macroteleia Westwood in Middle Miocene amber from Peru (Hymenoptera, Platygastridae s.l., Scelioninae)  

PubMed Central

Abstract A new species of the scelionine genus Macroteleia Westwood (Platygastridae s.l., Scelioninae) is described and figured from a female beautifully preserved in Middle Miocene amber from Peru. Macroteleia yaguarum Perrichot & Engel, sp. n., shows a unique combination of characters otherwise seen independently within its congeners. It is most similar to the modern M. surfacei Brues, but differs from it by the non-foveolate notauli, the contiguous punctures of the vertex, and the continuous propodeum. The new species is the first New World fossil of the genus, suggesting a Cretaceous origin for the group and a relatively old age of the South American, tropical African, and Australian faunas, and a younger age of the modern Holarctic faunas. PMID:25147461

Perrichot, Vincent; Antoine, Pierre-Olivier; Salas-Gismondi, Rodolfo; Flynn, John J.; Engel, Michael S.

2014-01-01

187

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

PubMed

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 VOR in plasma, tissues (heart, liver, spleen, lung, kidney and brain), bile, urine and feces were measured by HPLC-UV. The results showed that VOG and VOR have the similar pharmacokinetics. Both of them were absorbed quickly into plasma with maximal plasma concentrations of VOG and VOR being reached within 0.75 h. The mean elimination half-life (t(1/2)) of VOG and VOR were 2.53 h and 2.32 h, respectively. High levels of tissue distribution of VOG and VOR were observed in liver and kidney. No VOG and VOR were detected in brain tissue. There was no long-term accumulation of VOG and VOR in rat tissues examined. The total recovery of the dose in 24 hours was 64.91% (0.70% in urine; 64.21% in feces) for VOG and 89.01% (0.72% in urine; 88.29% in feces) for VOR. The cumulative VOG and VOR excreted in bile represented 0.58% and 13.38% of the doses, respectively. VOG and VOR in HLF were not efficiently absorbed in the rodent gastrointestinal tract. PMID:20096549

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

2010-07-01

188

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

SciTech Connect

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.

Olson, H.C.

1987-05-01

189

Life-history traits of the Miocene Hipparion concudense (Spain) inferred from bone histological structure.  

PubMed

Histological analyses of fossil bones have provided clues on the growth patterns and life history traits of several extinct vertebrates that would be unavailable for classical morphological studies. We analyzed the bone histology of Hipparion to infer features of its life history traits and growth pattern. Microscope analysis of thin sections of a large sample of humeri, femora, tibiae and metapodials of Hipparion concudense from the upper Miocene site of Los Valles de Fuentidueña (Segovia, Spain) has shown that the number of growth marks is similar among the different limb bones, suggesting that equivalent skeletochronological inferences for this Hipparion population might be achieved by means of any of the elements studied. Considering their abundance, we conducted a skeletechronological study based on the large sample of third metapodials from Los Valles de Fuentidueña together with another large sample from the Upper Miocene locality of Concud (Teruel, Spain). The data obtained enabled us to distinguish four age groups in both samples and to determine that Hipparion concudense tended to reach skeletal maturity during its third year of life. Integration of bone microstructure and skeletochronological data allowed us to identify ontogenetic changes in bone structure and growth rate and to distinguish three histologic ontogenetic stages corresponding to immature, subadult and adult individuals. Data on secondary osteon density revealed an increase in bone remodeling throughout the ontogenetic stages and a lesser degree thereof in the Concud population, which indicates different biomechanical stresses in the two populations, likely due to environmental differences. Several individuals showed atypical growth patterns in the Concud sample, which may also reflect environmental differences between the two localities. Finally, classification of the specimens' age within groups enabled us to characterize the age structure of both samples, which is typical of attritional assemblages. PMID:25098950

Martinez-Maza, Cayetana; Alberdi, Maria Teresa; Nieto-Diaz, Manuel; Prado, José Luis

2014-01-01

190

Life-History Traits of the Miocene Hipparion concudense (Spain) Inferred from Bone Histological Structure  

PubMed Central

Histological analyses of fossil bones have provided clues on the growth patterns and life history traits of several extinct vertebrates that would be unavailable for classical morphological studies. We analyzed the bone histology of Hipparion to infer features of its life history traits and growth pattern. Microscope analysis of thin sections of a large sample of humeri, femora, tibiae and metapodials of Hipparion concudense from the upper Miocene site of Los Valles de Fuentidueña (Segovia, Spain) has shown that the number of growth marks is similar among the different limb bones, suggesting that equivalent skeletochronological inferences for this Hipparion population might be achieved by means of any of the elements studied. Considering their abundance, we conducted a skeletechronological study based on the large sample of third metapodials from Los Valles de Fuentidueña together with another large sample from the Upper Miocene locality of Concud (Teruel, Spain). The data obtained enabled us to distinguish four age groups in both samples and to determine that Hipparion concudense tended to reach skeletal maturity during its third year of life. Integration of bone microstructure and skeletochronological data allowed us to identify ontogenetic changes in bone structure and growth rate and to distinguish three histologic ontogenetic stages corresponding to immature, subadult and adult individuals. Data on secondary osteon density revealed an increase in bone remodeling throughout the ontogenetic stages and a lesser degree thereof in the Concud population, which indicates different biomechanical stresses in the two populations, likely due to environmental differences. Several individuals showed atypical growth patterns in the Concud sample, which may also reflect environmental differences between the two localities. Finally, classification of the specimens’ age within groups enabled us to characterize the age structure of both samples, which is typical of attritional assemblages. PMID:25098950

Martinez-Maza, Cayetana; Alberdi, Maria Teresa; Nieto-Diaz, Manuel; Prado, José Luis

2014-01-01

191

Palaeoenvironmental Shifts Drove the Adaptive Radiation of a Noctuid Stemborer Tribe (Lepidoptera, Noctuidae, Apameini) in the Miocene  

PubMed Central

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

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

192

Miocene Vetigastropoda and Neritimorpha (Mollusca, Gastropoda) of central Chile  

NASA Astrophysics Data System (ADS)

Species of Vetigastropoda (Fissurellidae, Turbinidae, Trochidae) and one species of Neritimorpha (Neritidae) from the Navidad area, south of Valpara?´so, and the Arauco Peninsula, south of Concepción, are described. Among these, the Fissurellidae comprise Diodora fragilis n. sp., Diodora pupuyana n. sp., two additional unnamed species of Diodora, and a species resembling Fissurellidea. Turbinidae are represented by Cantrainea sp., and Trochidae include Tegula (Chlorostoma) austropacifica n. sp., Tegula (Chlorostoma) chilena n. sp., Tegula (Chlorostoma) matanzensis n. sp., Tegula (Agathistoma) antiqua n. sp., Bathybembix mcleani n. sp., Gibbula poeppigii [Philippi, 1887] n. comb., Diloma miocenica n. sp., Fagnastesia venefica [Philippi, 1887] n. gen. n. comb., Fagnastesia matanzana n. gen. n. sp., Calliostoma mapucherum n. sp., Calliostoma kleppi n. sp., Calliostoma covacevichi n. sp., Astele laevis [Sowerby, 1846] n. comb., and Monilea riorapelensis n. sp. The Neritidae are represented by Nerita (Heminerita) chilensis [Philippi, 1887]. The new genus Fagnastesia is introduced to represent low-spired trochoideans with a sculpture of nodes below the suture, angulated whorls, and a wide umbilicus. This Miocene Chilean fauna includes genera that have lived at the coast and in shallow, relatively warm water or deeper, much cooler water. This composition therefore suggests that many of the Miocene formations along the central Chilean coast consist of displaced sediments. A comparison with different fossil and Recent faunas from around the Pacific and South America indicates that the vetigastropod and neritid fauna from the Miocene of Chile has only minor affinities with taxa living near New Zealand, Argentina, and the tropical eastern Pacific at that time.

Nielsen, Sven N.; Frassinetti, Daniel; Bandel, Klaus

2004-09-01

193

Miocene sand distribution of the South Marsh Island and the Vermillion area, offshore Louisiana, Gulf of Mexico  

E-print Network

, helps in understanding the Miocene depositional settings, and promotes the knowledge of geology. The Miocene structural features in this area are east-west trending normal faults and salt diapir. Analysis of isopach and sand thickness maps indicates...

Kim, Jingoo

1997-01-01

194

Ostracoda (Arthropoda, Crustacea) in a Miocene oxygen minimum zone, Trinidad, West Indies: A test of the Platycopid Signal Hypothesis  

NASA Astrophysics Data System (ADS)

Studies of Recent ostracodes around the area of South America shed little light on the paleoenvironmental interpretation of Miocene assemblages. Consequently, interpretations of the Miocene ostracode assemblages must be supplemented using evidence from better documented taxa. Benthic foraminifera in samples from the Lower to Middle Miocene Brasso Formation at Brasso Village, Trinidad, have previously been used to distinguish three sample groupings (Beneath, Within and Above) around an oxygen minimum zone (OMZ), this being a layer of water within which dissolved oxygen concentrations can be as low as 0.1-1.0 mL/L. Using these same samples and the foraminiferal assemblage demarcations relative to the OMZ, this paper examines the associated and rich ostracode fauna of the Brasso Formation. The mean recovery of ostracode valves per sample was approximately three times greater in the Within OMZ sample group than in either of the Beneath OMZ or Above OMZ groups, perhaps reflecting the exclusion of macro-predators from within the OMZ. Individual rarefaction of species richness S to N = 300 valves was conducted for each sample group. This showed that S did not differ between the sample groups, ranging from 22.4 to 24.8. We used all ostracode species to model group separation. Based upon the Mahalanobis' criterion, we obtained significant group separation using a model with four taxa: Munseyella ex gr. minuta, Argilloecia posterotruncata, Munseyella sp. and Xestoleberis sp., while a fifth, Argilloecia spp., provided a significant but minor increase in separation probabilities over all groups. The two most abundant species (Bradleya sp., Gangamocytheridea reticulata) were thus not the best species for detecting the OMZ. Platycopid ostracodes of the genus Cytherella were found throughout the section, rather than concentrated within the OMZ, which contradicts the Platycopid Signal Hypothesis that OMZs are characterized by platycopid dominance. The total distribution and turnover of both ostracodal and foraminiferal assemblages were compared and contrasted quantitatively using a total assemblage turnover index (ATI) and the paleoenvironmental importance evaluated. The correlated between-sample ATI is for both groups lowest within the OMZ.

Wilson, Brent; Coimbra, João C.; Hayek, Lee-Ann C.

2014-10-01

195

Paleoceanographic implications of Miocene deep-sea hiatuses.  

USGS Publications Warehouse

Miocene paleoceanographic evolution exhibits major changes resulting from the opening and closing of passages, the subsequent changes in oceanic circulation, and development of major Antarctic glaciation. The consequences and timing of these events can be observed in variations in the distribution of deep-sea hiatuses, sedimentation patterns, and biogeographic distribution of planktic organisms. The main aspects of the present oceanic circulation system and sediment distribution pattern were established by 13.5 to 12.5 Ma (hiatus NH 3), coincident with the establishment of a major East Antarctic ice cap. -from Authors

Keller, G.; Barron, J.A.

1983-01-01

196

Miocene reef facies of pelagian block, central Mediterranean  

SciTech Connect

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.

Pedley, H.M.

1988-02-01

197

The beaver Anchitheriomys from the Miocene of Central Europe  

SciTech Connect

New finds of teeth and mandibles of Anchitheriomys from the Hambach opencast lignite mine in Northwest Germany and the first detailed descriptions of other mandibles from South Germany and Switzerland allow a review of the Central European specimens of this rare beaver genus. The metric variation of cheek teeth and especially the great differences in dimensions of incisors can be much better assessed. The observed range in size can be attributed to ontogenetic changes, and all material is assigned to Anchitheriomys suevicus. Stratigraphically, this species is restricted to the early middle Miocene, European Mammalian Neogene biozones MN 5-6.

Stefen, C.; Mors, T. [Museum Tierkunde, Dresden (Germany)

2008-09-15

198

Miocene shale tectonics in the Moroccan margin (Alboran Sea)  

NASA Astrophysics Data System (ADS)

The Betic (Southern Spain) and Rif (Morocco) mountains form an arcuate belt that represents the westernmost termination of the peri-mediterranean Alpine mountain chain. The Miocene Alboran Basin and its subbasins is located in the hinterland of the Betic-Rif belt. It is considered to be a back-arc basin that developed during the coeval westward motion of the Alboran domain and the extensional collapse of previously thickened crust of the Betic-Rif belt. The Western Alboran Basin (WAB) is the major sedimentary depocenter with a sediment thickness in excess of 10 km, it is bordered by the Gibraltar arc, the volcanic Djibouti mounts and the Alboran ridge. Part of the WAB is affected by shale tectonics and associated mud volcanism. High-quality 2D seismic profiles acquired on the Moroccan margin of the Alboran Basin during the last decade reveal the multiple history of the basin. This study deals with the analysis of a number of these seismic profiles that are located along and orthogonal to the Moroccan margin. Seismic stratigraphy is calibrated from industrial wells. We focus on the interactions between the gravity-driven tectonic processes and the sedimentation in the basin. Our seismic interpretation confirms that the formation of the WAB began in the Early Miocene (Aquitanian - Burdigalian). The fast subsidence of the basin floor coeval to massive sedimentation induced the undercompaction of early miocene shales during their deposition. Downslope migration of these fine-grained sediments initiated during the deposition of the Langhian siliciclastics. This gravity-driven system was accompanied by continuous basement subsidence and induced disharmonic deformation in Mid Miocene units (i.e. not related to basement deformation). The development of shale-cored anticlines and thrusts in the deep basin is the result of compressive deformation at the front of the gravity-driven system and lasted for ca. 15 Ma. The compressive front has been re-activated by strong siliciclastic deposition, such as in the Serravalian-Tortonian period or more recently during the Quaternary contourites deposition. The Messinian dessication of the Mediterranean Sea and the following catastrophic Pliocene reflooding caused or enhanced re-activation of the deformation.

Do Couto, D.; El Abbassi, M.; Ammar, A.; Gorini, C.; Estrada, F.; Letouzey, J.; Smit, J.; Jolivet, L.; Jabour, H.

2011-12-01

199

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

SciTech Connect

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.

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

200

The Costa Rican Jurassic to Miocene oceanic complexes: Origin, tectonics and relations  

NASA Astrophysics Data System (ADS)

The occurrences of oceanic assemblages on the Pacific shore of Costa Rica are part of an intricate group of complexes with different tectonic origins. Although they are dismembered and disrupted, they are the only available inland source of information to decipher the evolution of this active margin. Six main regions are described in this paper: (1) Santa Elena Peninsula, constituted by a supra-subduction zone (Santa Elena Nappe), that is overthrusting an igneous-sedimentary Aptian-Cenomanian sequence (Santa Rosa Accretionary Complex), which includes OIB (Ocean Island Basalts) portions, (2) the Nicoya Complex, which is a Jurassic-Cretaceous chert sediment pile disrupted and detached from its original basement by multiple magmatic events that occurred during the formation of the CLIP (Caribbean Large Igneous Province), (3) the Tortugal area formed by the Tortugal Suite with OIB signature and surrounded by Nicoya Complex outcrops, (4) the Herradura Block composed of the Tulín Formation to Maastrichtian to Lower Eocene OIB accreted oceanic island and the Nicoya Complex as basement, (5) Quepos Block correlated with the Tulín Formation, (6) the Osa-Burica Block composed of the Golfito and Burica Terranes (geochemically and chronologically correlated to the Nicoya Complex), Rincón Block (Early Paleocene to Early Eocene accreted seamounts), and the Miocene Osa-Caño Accretionary Complex. The Santa Rosa Accretionary Complex together with the Tortugal Suite have OIB signatures and possibly without Galapagos hotspot geochemical affinity. These coincidences would be explained by the hypothetical existence of an "autochthonous" Cretaceous basement formed by these two regions together with the rest of the Caribbean. Costa Rican basement is constituted by several CLIP portions and seamounts accreted from the end of Cretaceous in the northwest to the Miocene in the southeast, forming the diverse oceanic occurrences of the Pacific, which are mainly connected to the Galapagos hotspot activity.

Denyer, Percy; Gazel, Esteban

2009-12-01

201

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

E-print Network

to middle Miocene (~20 ­ 14 Ma) vegetation, topography, bathymetry and modern13 CO2. A decrease; Zachos et al. 2008), tropical vegetation extended poleward (Cosgrove et al. 2002;35 Wolfe 1985 and temporal coverage of climate proxies has limited the characterisation of52 #12;4 global Miocene climate

Müller, Dietmar

202

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

E-print Network

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

Brest, Université de

203

Ventilation of the Miocene Arctic Ocean: An idealized model study Bijoy Thompson,1  

E-print Network

Ventilation of the Miocene Arctic Ocean: An idealized model study Bijoy Thompson,1 Johan Nilsson,2 Ridge in the central Arctic Ocean, which suggests a transition from anoxic to oxic condition during indicate that the early Miocene Arctic Ocean became well ventilated when the Fram Strait reached a width

Nycander, Jonas

204

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

Microsoft Academic Search

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

Fay Woodruff; Samuel M. Savin; Linda Abel

205

Antarctic environmental variability since the late Miocene: ODP Site 745, the East Kerguelen sediment drift  

E-print Network

Antarctic environmental variability since the late Miocene: ODP Site 745, the East Kerguelen surrounding the timing of Miocene to present East Antarctic ice sheet stability and oceanic environmental change. Our results show three periods of greatly enhanced accumulation of Antarctic-derived sediment

206

Quantitative reconstruction of Miocene climate patterns and evolution in Southern China based on plant fossils  

Microsoft Academic Search

Southern China, especially Yunnan, has undergone high tectonic activity caused by the uplift of Himalayan Mountains during the Neogene, which led to a fast changing palaeogeography. Previous study shows that Southern China has been influenced by the Asian Monsoon since at least the Early Miocene. However, it is yet not well understood how intense the Miocene monsoon system was. In

Yi-Feng Yao; Angela A. Bruch; Volker Mosbrugger; Cheng-Sen Li

2011-01-01

207

PRELIMINARY ASSESSMENT OF THE LATE MIOCENE AVIFAUNA FROM LEMUDONG'O, KENYA  

Microsoft Academic Search

The small collection of avian skeletal remains, including those of an eagle, an owl, and possibly a pheasant, from Lemudong'o provides additional information about terrestrial late Miocene avifaunas in east Africa. Large phasianids are known elsewhere in the Miocene of Africa, but pheasants are naturally absent today from the continent. The presence of two predatory bird species at the locality

THOMAS A. STIDHAM

208

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

E-print Network

Miocene, Spain) Hemmo A. Abels a,b, , Hayfaa Abdul Aziz a,b , Wout Krijgsman b , Sander J.B. Smeets Madrid Basin (central Spain) is dated bio-magnetostratigraphically between 15.2 Ma and 11.5 Ma-dominated intervals is similar to a previously documented Late Miocene shift in the Teruel Basin of northeast Spain

Utrecht, Universiteit

209

Sr-isotopic, paleomagnetic, and biostratigraphic calibration of horse evolution: Evidence from the Miocene of Florida  

Microsoft Academic Search

During the middle Miocene an explosive adaptive radiation resulted in the advent of grazing horses with high-crowned teeth in North America. New Sr isotopic, paleomagnetic, and biostratigraphic evidence from the Miocene marine and nonmarine sequence of the Florida panhandle calibrates the base of this adaptive radiation. The transition from the primitive outgroup species \\

Bruce J. MacFadden; J. Daniel Bryant; Paul A. Mueller

1991-01-01

210

Sr-isotopic, paleomagnetic, and biostratigraphic calibration of horse evolution: Evidence from the Miocene of Florida  

Microsoft Academic Search

During the middle Miocene an explosive adaptive radiation resulted in the advent of grazing horses with high-crowned teeth in North America. New Sr isotopic, paleomagnetic, and biostratigrahic evidence from the Miocene marine and nonmarine sequence of the Florida panhandle calibrates the base of this adaptive radiation. The transition from the primitive outgroup species 'Parahippus' leonensis to the most primitive high-crowned

Bruce J. MacFadden; J. Daniel Bryant; Paul A. Mueller

1991-01-01

211

Middle to late Miocene oxygen isotope stratigraphy of ODP site 1085 (SE Atlantic): new constrains on Miocene climate variability and sea-level fluctuations  

Microsoft Academic Search

The middle Miocene ?18O increase represents a fundamental change in earth's climate system due to a major expansion and permanent establishment of the East Antarctic Ice Sheet accompanied by some effect of deepwater cooling. The long-term cooling trend in the middle to late Miocene was superimposed by several punctuated periods of glaciations (Mi-Events) characterized by oxygen isotopic shifts that have

T. Westerhold; T. Bickert; U. Röhl

2005-01-01

212

Plate-induced Miocene extension in southern California  

SciTech Connect

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.

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

1992-01-01

213

Upper Miocene reef complex of Mallorca, Balearic Islands, Spain  

SciTech Connect

The late Tortonian-Messinian coral reef platform of south Mallorca onlaps a folded middle late Miocene carbonate platform on which progradation of up to 20 km occurs. Vertical sea cliffs (up to 100 m high) superbly show the last 5 km of this progradation and complement the numerous water-well cores from the island interior. The coral reef platform consists of a series of progradational-accretional sequences and erosion surfaces of different orders of magnitude. The first-order sequence is bounded by significant erosion surfaces with breccias, major facies shifts, and vertical accretion. The second-order sequences show accretional events of up to 100 m thick with 1 to 2 km of progradation, and the third-order sequences occur in packages of tens of meters. Individual reef units are bounded by minor erosional surfaces and define the fourth-order sequences. This composite accretional-progradational architecture implies cyclic variations of relative sea level. Episodes of sea level rise were responsible for the vertical accretion. Sea level falls produced the erosional surfaces; most progradation occurred during lowering sea level episodes. This sedimentological framework of the Mallorca reef suggests late Miocene glacio-eustatic fluctuations of sea level similar to the Quaternary.

Pomar, L.

1988-01-01

214

Millennial scale climatic responses through a Late Miocene precession cycle  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

215

Tropical sea surface temperature variability near the Oligocene - Miocene boundary  

NASA Astrophysics Data System (ADS)

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.

Zhang, Y.; Pagani, M.

2010-12-01

216

A mantle plume beneath California? The mid-Miocene Lovejoy Flood Basalt, northern California  

USGS Publications Warehouse

The Lovejoy basalt represents the largest eruptive unit identified in California, and its age, volume, and chemistry indicate a genetic affinity with the Columbia River Basalt Group and its associated mantle-plume activity. Recent field mapping, geochemical analyses, and radiometric dating suggest that the Lovejoy basalt erupted during the mid-Miocene from a fissure at Thompson Peak, south of Susanville, California. The Lovejoy flowed through a paleovalley across the northern end of the Sierra Nevada to the Sacramento Valley, a distance of 240 km. Approximately 150 km3 of basalt were erupted over a span of only a few centuries. Our age dates for the Lovejoy basalt cluster are near 15.4 Ma and suggest that it is coeval with the 16.1-15.0 Ma Imnaha and Grande Ronde flows of the Columbia River Basalt Group. Our new mapping and age dating support the interpretation that the Lovejoy basalt erupted in a forearc position relative to the ancestral Cascades arc, in contrast with the Columbia River Basalt Group, which erupted in a backarc position. The arc front shifted trenchward into the Sierran block after 15.4 Ma. However, the Lovejoy basalt appears to be unrelated to volcanism of the predominantly calc-alkaline Cascade arc; instead, the Lovejoy is broadly tholeiitic, with trace-element characteristics similar to the Columbia River Basalt Group. Association of the Lovejoy basalt with mid-Miocene flood basalt volcanism has considerable implications for North American plume dynamics and strengthens the thermal "point source" explanation, as provided by the mantle-plume hypothesis. Alternatives to the plume hypothesis usually call upon lithosphere-scale cracks to control magmatic migrations in the Yellowstone-Columbia River basalt region. However, it is difficult to imagine a lithosphere-scale flaw that crosses Precambrian basement and accreted terranes to reach the Sierra microplate, where the Lovejoy is located. Therefore, we propose that the Lovejoy represents a rapid migration of plume-head material, at ??20 cm/yr to the southwest, a direction not previously recognized. ?? 2008 The Geological Society of America.

Garrison, N.J.; Busby, C.J.; Gans, P.B.; Putirka, K.; Wagner, D.L.

2008-01-01

217

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

PubMed

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

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

2002-06-01

218

Porosity evolution of upper Miocene reefs, Almeria Province, southern Spain  

USGS Publications Warehouse

Sea cliffs 40 km east of Almeria, southeastern Spain, expose upper Miocene reefs and patch reefs of the Plomo formation. These reefs are formed of scleractinian corals, calcareous algae, and mollusks. The reef cores are as much as 65 m thick and several hundred meters wide. Fore-reef talus beds extend 1,300 m across and are 40 m thick. The reefs and reef breccias are composed of calcific dolomite. They lie on volcanic rocks that have a K-Ar date of 11.5 m.y. and in turn are overlain by the upper Miocene Vicar Formation. In the reef cores and fore-reef breccia beds, porosity is both primary and postdepositional. Primary porosity is of three types: (a) boring clam holes in the scleractinian coral heads, cemented reef rocks, and breccias; (b) intraparticle porosity within the corals, Halimeda plates, and vermetid worm tubes; and (c) interparticle porosity between bioclastic fragments and in the reef breccia. Postdepositional moldic porosity was formed by the solution of aragonitic material such as molluscan and coral fragments. The Plomo reef carbonate rocks have high porosity and permeability, and retain a great amount of depositional porosity. Pores range in size from a few micrometers to 30 cm. The extensive intercrystalline porosity and high permeability resulted from dolomitization of micritic matrix. Dolomite rhombs are between 10 and 30 ? across. More moldic porosity was formed by the dissolution of the calclte bioclasts. Some porosity reduction has occurred by incomplete and partial sparry calcite infilling of interparticular, moldic, and intercrystalline voids. The high porosity and permeability of these reefs make them important targets for petroleum exploration in the western Mediterranean off southern Spain. In these offshore areas in the subsurface the volcanic ridge and the Plomo reef complex are locally onlapped or overlapped by 350 m or more of Miocene(?) and Pliocene fine-grained sedimentary rocks. The possibility exists that the buried Plomo reef deposits may form traps for oil and gas in the offshore areas southwest of the type locality. Stratigraphic traps also may occur where the Neogene sequence above the Plomo reef complex onlaps the volcanic ridge.

Armstrong, A.K.; Snavely, P.D.; Addicott, W.O.

1980-01-01

219

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

SciTech Connect

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.

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

1993-02-01

220

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

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

221

Effects on growth and cost of production of Arizona ash, Indian hawthorn, Southern waxmyrtle, and live oak sequentially produced in combinations of Cu-treated and non-treated 0.24 L., 2.7 L and 10.4 L or 12.7 L containers  

E-print Network

velutina Torr. (Arizona ash), Quercus virginians Mill. (live oak), and Rapheolepis indica Lindl. (lndian hawthorn) and two-hundred forty seedlings of Myrica cerebra L. (waxmyrtle) were grown in College Station, Texas in 0.24 L containers half...

Obst, Steven Paul

1998-01-01

222

Ruminant diets and the Miocene extinction of European great apes  

PubMed Central

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

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

2010-01-01

223

Gulf of Mexico Miocene CO2 Site Characterization Mega Transect  

SciTech Connect

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

Meckel, Timothy; Trevino, Ramon

2014-09-30

224

A Miocene submarine volcano at Low Layton, Jamaica  

NASA Astrophysics Data System (ADS)

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.

Wadge, G.

225

A Miocene submarine volcano at Low Layton, Jamaica  

NASA Technical Reports Server (NTRS)

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.

Wadge, G.

1982-01-01

226

Simultaneous Miocene Extension and Shortening in the Himalayan Orogen  

NASA Astrophysics Data System (ADS)

The South Tibetan detachment system separates the high-grade metamorphic core of the Himalayan orogen from its weakly metamorphosed suprastructure. It is thought to have developed in response to differences in gravitational potential energy produced by crustal thickening across the mountain front. Geochronologic data from the Rongbuk Valley, north of Qomolangma (Mount Everest) in southern Tibet, demonstrate that at least one segment of the detachment system was active between 19 and 22 million years ago, an interval characterized by large-scale crustal thickening at lower structural levels. These data suggest that decoupling between an extending upper crust and a converging lower crust was an important aspect of Himalayan tectonics in Miocene time.

Hodges, K. V.; Parrish, R. R.; Housh, T. B.; Lux, D. R.; Burchfiel, B. C.; Royden, L. H.; Chen, Z.

1992-11-01

227

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

E-print Network

A new termite bug in Miocene amber from the Dominican Republic (Hemiptera, Termitaphididae)61 A new termite bug in Miocene amber from the Dominican Republic (Hemiptera, Termitaphididae) Michael S. Engel Division of Entomology, Natural History... | Received 04 September 2009 | Accepted 12 October 2009 | Published 23 October 2009 urn:lsid:zoobank.org:pub:76B0B285-3584-4584-8E83-2CA543211D06 Citation: Engel MS (2009) A new termite bug in Miocene amber from the Dominican Republic (Hemiptera, Termita...

Engel, Michael S.

2009-10-23

228

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

PubMed

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

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

2015-01-01

229

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

PubMed Central

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

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

2012-01-01

230

Miocene reef and nonreef carbonate rocks in Japan  

SciTech Connect

Japan's main islands experienced temperature climates throughout the Neogene with a tropical invasion around 16 Ma (early middle Miocene). This climatic warming, accompanied by a eustatic sea level rise, caused the unusual occurrence of reef facies, mangrove deposits, and lateritic beds in Japan. In cooler climates both before and after reef growth, sediments rich in bryozoan and algal material were widespread. Reef rocks emplaced as penecontemporaneous olistoliths in deep-water clastics at the Pacific coast of central Honshu are characterized by a wide lithologic spectrum, ranging from grainstone to bindstone. These rocks include rudstone and floatstone, which are rich in coralline algae (encrusting forms such as Lithophyllum and Mesophyllum and articulate forms such as Amphiroa) and codiacean algae (Halimeda) with hermatypic corals and large benthic formainifera (e.g., Nephrolepidina and Miogypsina) being less common. Two types of dolomite occur: (1) limpid dolomite with O/sup 18/ = -5.77 and with bipyramidal quartz and (2) microcrystalline dolomite with O/sup 18/ = 2.00 and with length-slow chalcedony. While microcrystalline dolomite tends to predominate in muddy matrix material, limpid dolomite appears to fill pores, some of which are moldic. Younger nonreef carbonate rocks, as occur on the Noto Peninsula of central Honshu, are commonly cross-bedded, contain Bryozoa, mollusks, small foraminifera, and echinoids, and are locally dolomitized. These dolomites are ascribed to a mixed-water origin. A different type of nonreef, yet reservoir-forming, dolostone occurs in the late middle Miocene of northeast Honshu and is interpreted to have formed as a transformation from bathyal opal.

Konishi, K.

1988-01-01

231

A middle Miocene relative paleointensity record from the Equatorial Pacific  

NASA Astrophysics Data System (ADS)

We present a high-resolution magnetostratigraphy and relative paleointensity (RPI) record derived from the upper 85 m of IODP Site U1336, an Equatorial Pacific early to middle Miocene succession recovered during Expedition 320/321. The magnetostratigraphy is well resolved with reversals typically located to within a few centimeters resulting in a well-constrained age model. The lowest normal polarity interval, from 85 to 74.87 m, is interpreted as the later part of Chron C6n (18.614-19.599 Ma). Thirty-three other magnetozones occur from 74.87 to 0.85 m, which are interpreted to represent the continuous sequence of chrons onset of Chron C5Er (18.748 Ma) to the end of Chron C5An.1n (12.014 Ma). We identify three putative previously-unrecognized subchrons within Chron C5Cn.1n, Chron 5Bn.1r, and C5ABn. Sedimentation rates vary from about 7 to 15 m/Myr with a mean of about 10 m/Myr. We observe rapid, apparent changes in the sedimentation rate at geomagnetic reversals between ˜16 and 19 Ma that indicate a calibration error in geomagnetic polarity timescale (ATNTS2004). The remanence is carried mainly by non-interacting particles of fine-grained magnetite, which have FORC distributions characteristic of biogenic magnetite. Given the relative homogeneity of the remanence carriers throughout the 85-m-thick succession and the fidelity with which the remanence is recorded, we have constructed a relative paleointensity (RPI) record that provides new insights into middle Miocene geomagnetic field behavior. The RPI record indicates a gradual decline in field strength between 18.5 Ma and 14.5 Ma, and indicates no discernible link between RPI and either chron duration or polarity state.

Ohneiser, Christian; Acton, Gary; Channell, James E. T.; Wilson, Gary S.; Yamamoto, Yuhji; Yamazaki, Toshi

2013-07-01

232

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

PubMed

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

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

2014-01-01

233

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

PubMed

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

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

2014-07-01

234

Paleomagnetic Evidence for 'Oroclinal' Rotation in the Central Japan Arc from Early Miocene Sedimentary Rocks  

NASA Astrophysics Data System (ADS)

In this study we focus on the general curvilinear trend of geologic zones (mainly accretionary complexes) in the central Japan arc. This feature is best represented by the Median Tectonic Line (MTL), a major boundary fault between the Sanbagawa high-P/T and Ryoke low-P/T metamorphic belts. Previous paleomagnetic data imply that the curvature is of 'oroclinal' origin, that is, the curved system was originally straight and formed after the accretionary processes and metamorphism. In order to quantitatively assess this possibility, we have carried out a paleomagnetic study for Early Miocene sedimentary rocks from two areas (Morozaki in Aichi Prefecture and Tomikusa in Nagano Prefecture) in central Japan. In Morozaki, oriented cores were collected at 22 sites from felsic tuff and siltstone beds of the Himaka Formation, which is the lowermost formation of the sedimentary sequence in this area. In Tomikusa, cores were taken at 24 sites from various lithologies of the Tomikusa Group. Rock specimens were subjected to stepwise alternating-field or thermal demagnetization in order to extract characteristic remanent magnetization (ChRM) components. Rock magnetic experiments suggest that ChRMs are carried primarily by magnetite. The Himaka Formation sites have reverse-polarity ChRM directions, and we consider this formation to be correlative to Chronozone C5Dr (18.056-17.533 Ma). The Tomikusa Group indicates both normal and reverse polarities and can be correlated to Chronozone C5D (18.056-17.235 Ma). Mean paleomagnetic directions for the two areas were determined and, together with existing paleomagnetic data from other areas, they were used for a paleomagnetic orocline test with a declination-strike diagram. Our result strongly suggests that the geologic zones and boundary faults (including the MTL) in the central Japan arc was straight before 18 Ma. We suggest that the oroclinal rotation results from a combination of the clockwise rotation of the southwestern Japan arc and the start of collision of the Izu-Bonin-Mariana arc with the central Japan arc, both during the late Early to early Middle Miocene (ca. 17-15 Ma).

Hoshi, H.; Sako, K.; Namikawa, T.; Ando, Y.

2013-12-01

235

Phylogeny and rapid northern and southern hemisphere speciation of goldfinches during the Miocene and Pliocene epochs.  

PubMed

Mitochondrial cytochrome b (cyt b) from 25 out of 31 extant goldfinches, siskins, greenfinches and redpolls (genus Carduelis) has been sequenced from living samples taken around the world, specimens have also been photographed. Phylogenetic analysis consistently gave the same groups of birds, and this grouping was generally related to geographical proximity. It has been supposed that Pleistocene glaciations played a crucial role in the origin of extant diversity and distribution of Northern Hemisphere vertebrates. Molecular comparison of most extant songbird species belonging to the genus Carduelis does not support this assertion. The fossil record of chicken and pheasant divergence time has been used to calibrate the molecular clock; cyt b DNA dendrograms suggest that speciation in Carduelinae birds occurred during the Miocene and Pliocene Epochs (9-2 million years ago) in both the Northern and Southern Hemispheres. Only about 4% average amount of nucleotide substitution per lineage is found between the most distant Carduelis species; this suggests a remarkably rapid radiation when compared with the radiation of other passerine songbird genera. In addition, a continuum of small songbird speciation may be found during the Miocene Epoch in parallel with speciation of other orders (i.e. Galliformes, chicken/pheasant). Pleistocene glaciations may have been important in subspeciation (i.e. Eastern European grey-headed goldfinches/Western European black-headed goldfinches) and also in ice-induced vicariance (isolation) (i.e. siskin in Western Europe vs. siskin in Far East Asia) around the world. European isolated Serinus citrinella (citril finch) is not a canary, but a true goldfinch. South American siskins have quickly radiated in the last 4 million years coinciding with the emergence of the Isthmus of Panama; probably, a North American siskin related to C. notata invaded a suitable and varied biotope (the South American island) for Carduelis birds. North American goldfinches may be renamed as siskins, because they have a distant genetic relationship with European goldfinches. Genus Acanthis could be dropped, and thus redpolls should be separated from twite and linnet, the latter (Europeans) probably being related to American goldfinches. Also, reproductive barriers are observed between closely related species and not between other more distant ones. Finally, a tentative classification for genus Carduelis species is suggested. PMID:9791543

Arnaiz-Villena, A; Alvarez-Tejado, M; Ruíz-del-Valle, V; García-de-la-Torre, C; Varela, P; Recio, M J; Ferre, S; Martínez-Laso, J

1998-09-01

236

Miocene climate seasonality in southern India - first direct evidence for a weak Indian monsoon during the Middle Miocene Climate Optimum  

NASA Astrophysics Data System (ADS)

The Asian monsoon is an integral component of the global climate system. This large-scale atmospheric circulation comprises the East Asian summer and winter monsoon and the Indian monsoon subsystems, all characterized by seasonal reversing winds and precipitation changes associated with asymmetric heating of land and sea. The Neogene monsoon history is mainly reconstructed from chemical and physical weathering rates recorded in widely continuous marine sequences of the Indus Fan, Bengal Fan and South China Sea, which, depending on the source, physiography and sediment, indicate drier or wetter climates. These indirect climate proxies display an unusually dry period during the Middle Miocene Climate Optimum (MMCO, 16.5-15 Ma). As part of the FWF-projects P18189, P21414 and P23492, we present an Early/Middle Miocene coastal palynoflora record from the siliciclastic Ambalapuzha Formation at the coastal cliff of Varkala (Kerala Basin, SW India). Pollen assemblages and facies document a coastal wetland with mangrove vegetation. The Coexistence Approach was applied for palaeoclimatic reconstructions. This method uses climatic tolerances of all nearest living relatives known for a fossil flora by assuming that the tolerances of a fossil taxon are not significantly different from its modern counterpart. The maximum overlap of the environmental tolerances of all nearest living relatives (coexistence interval) is then regarded as being indicative of the most likely palaeoenvironment. By enquiring the Palaeoflora Database (http://www.palaeoflora.de/), the palaeoclimatic parameters of the pollen flora were calculated. The reconstructed climatic parameters for the MMCO show a seasonal precipitation pattern with a dry and a wet period and moderate rainfalls during the warmest period, which is comparable to the present day annual precipitation cycle in coastal Kerala, and affirms the presence of a monsoon-like atmospheric circulation over South India during the MMCO. However, the precipitation amounts during the wet (average 75%) and the warmest period (average 68%) were significantly reduced compared to today, while the rainfalls during the dry seasons are in the same order. This implies a weak Indian monsoon during the MMCO and a low thermal land - sea gradient between the Eurasian landmass and the Indian Ocean. Although a ~3°C warmer global climate during the MMCO and a weaker monsoon accounts for a higher near-surface air temperature during summer, the calculated mean annual temperature (MAT; 24.4°C) is 2.7°C lower than at present. The estimated warmest month temperature is, however, in the same range as today. Therefore, the low coldest month temperature (CMT; 20.6-22.8°C) in the Miocene has to account for the high MAT difference. This parameter represents the lower temperature threshold of the Varkala flora, and displays only the minimum temperature during the coldest month, which is significantly lower than the average CMT. Accordingly, the Miocene CMT approximates the present 24-h minimum temperature during the coldest month in Kerala (22.4°C). The reconstructed seasonal temperature cycle supports climate models, which suggest a higher temperature increase in mid-latitudes than in low-latitudes as well as warmer equatorial sea surface temperatures during the MMCO.

Piller, W. E.; Reuter, M.; Kern, A. K.; Harzhauser, M.

2012-04-01

237

Lithostratigraphy of the Te Kuiti Group: A revision  

Microsoft Academic Search

The Te Kuiti Group in the South Auckland area comprises nine formations of late Eocene to early Miocene age, and is dominated by calcareous sandstones, siltstones, and limestones. This paper revises the stratigraphy and nomenclature of the group. Te Akatea Siltstone and Whaingaroa Siltstone are renamed Te Akatea Formation and Whaingaroa Formation, respectively, and the base of Te Akatea Formation

P. J. White; B. C. Waterhouse

1993-01-01

238

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

NASA Astrophysics Data System (ADS)

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.

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

2000-03-01

239

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

E-print Network

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...

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

2011-03-10

240

Early to middle Miocene foraminifera from the deep-sea Congo Fan, offshore Angola  

E-print Network

of planktonic foraminifera. Faunas show close affinities to those of the eastern Venezuela Basin, Gulf of Mexico. Planktonic foraminifera con- strain the age to Early ­ Middle Miocene, and d18 O records reveal the Mi1 (~16

Kaminski, Michael A.

241

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

USGS Publications Warehouse

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

Barron, J.A.; Keller, G.

1982-01-01

242

Correlation of Miocene sequences and hydrogeologic units, New Jersey Coastal Plain  

Microsoft Academic Search

We have developed a Miocene sequence stratigraphic framework using data from recently drilled boreholes in the New Jersey Coastal Plain. Sequences are shallowing upward, unconformity-bounded units; fine-grained shelf and prodelta sediments grade upward to delta front and shallow-marine sands, corresponding to confining bed—aquifer couplets. By dating Miocene sequences using Sr-isotope stratigraphy, and mapping with borehole data and geophysical logs, we

Peter J. Sugarman; Kenneth G. Miller

1997-01-01

243

Geochemical characteristics of the Miocene eolian deposits in China: Their provenance and climate implications  

Microsoft Academic Search

In the Loess Plateau in northern China, the Quaternary loess-soil sequences, the Hipparion Red Earth of eolian origin (Red Clay), and the Miocene loess-soil sequences constitute a near-continuous terrestrial record of paleoclimates for the past 22 Ma. In this study, Miocene loess and paleosol samples from Qinan (QA-I) were analyzed for their major, trace, and rare earth element chemistry and

Meiyan Liang; Zhengtang Guo; A. Julia Kahmann; Frank Oldfield

2009-01-01

244

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

NASA Astrophysics Data System (ADS)

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.

Scotese, C. R.

2001-05-01

245

Subcellular preservation in giant ostracod sperm from an early Miocene cave deposit in Australia.  

PubMed

Cypridoidean ostracods are one of a number of animal taxa that reproduce with giant sperm, up to 10 000 µm in length, but they are the only group to have aflagellate, filamentous giant sperm. The evolution and function of this highly unusual feature of reproduction with giant sperm are currently unknown. The hypothesis of long-term evolutionary persistence of this kind of reproduction has never been tested. We here report giant sperm discovered by propagation phase contrast X-ray synchrotron micro- and nanotomography, preserved in five Miocene ostracod specimens from Queensland, Australia. The specimens belong to the species Heterocypris collaris Matzke-Karasz et al. 2013 (one male and three females) and Newnhamia mckenziana Matzke-Karasz et al. 2013 (one female). The sperm are not only the oldest petrified gametes on record, but include three-dimensional subcellular preservation. We provide direct evidence that giant sperm have been a feature of this taxon for at least 16 Myr and provide an additional criterion (i.e. longevity) to test hypotheses relating to origin and function of giant sperm in the animal kingdom. We further argue that the highly resistant, most probably chitinous coats of giant ostracod sperm may play a role in delaying decay processes, favouring early mineralization of soft tissue. PMID:24827442

Matzke-Karasz, Renate; Neil, John V; Smith, Robin J; Symonová, Radka; Mo?kovský, Libor; Archer, Michael; Hand, Suzanne J; Cloetens, Peter; Tafforeau, Paul

2014-07-01

246

Miocene Slab Detachment in Central Mexico: Causes and Consequences  

NASA Astrophysics Data System (ADS)

I propose that the lower part of the Farallon slab subducted beneath Mexico has detached twice during the Miocene. Initiation of slab detachment is a consequence of the incoming of increasingly buoyant oceanic crust at the paleotrench off Baja California and, eventually, the capture by the Pacific plate of the microplates left over by the Farallon plate that produced a retrograde motion of the shallow part of the slab. Our first integration of the geology of the whole central Mexico reveals a number of features that support the detachment model and allow inferring the location through time of these events. A main consequence of detachments is the influx of hotter and geochemically enriched sub-slab material into the slab-free area. The process is thus expected to generate a pulse of volcanism and a geochemically heterogeneous mantle wedge. A first detachment is inferred to have begun shortly before the contact between the Pacific and North America plate at 28.5 Ma. A tear in the slab propagated to the SSE, producing a transient thermal anomaly, ignimbrite flare up, and extension at ~24-20 Ma in the southern Sierra Madre Occidental. A second detachment event is inferred as a result of the end of subduction off the southern half of Baja California at 12.5 Ma. In this case the slab detached from the southern Gulf of California toward the ESE, paralleling the southern Mexico trench system. This event caused an eastward migrating mafic pulse of volcanism, presently observed in the northern part of the Trans-Mexican Volcanic Belt (TMVB), between 11 and 7 Ma. New geochronological and geochemical data suggest the continuation of the detachment to the SSE in Veracruz state (Sierra de Tantima, Alamo, Poza Rica, Palma Sola and Los Tuxtlas volcanic fields). The occurrence of OIB volcanism in the TMVB since the end of Miocene is explained by the influx of enriched asthenospheric material into the gap formed by the detachment, enhanced by the corner flow induced by the continuing subduction. Slowing convergence of the Rivera and Cocos plate with respect to North America after ~10 Ma is a likely consequence of the loss of slab pull following the last detachment event. Our case study suggests that mantle dynamic is driven from above (subducting plate) and that slab detachment may produce a plume-like thermal/magmatic effect in the upper plate.

Ferrari, L.

2002-12-01

247

Early Miocene origin and cryptic diversification of South American salamanders  

PubMed Central

Background The currently recognized species richness of South American salamanders is surprisingly low compared to North and Central America. In part, this low richness may be due to the salamanders being a recent arrival to South America. Additionally, the number of South American salamander species may be underestimated because of cryptic diversity. The aims of our present study were to infer evolutionary relationships, lineage diversity, and timing of divergence of the South American Bolitoglossa using mitochondrial and nuclear sequence data from specimens primarily from localities in the Andes and upper Amazon Basin. We also estimated time of colonization of South America to test whether it is consistent with arrival via the Panamanian Isthmus, or land bridge connection, at its traditionally assumed age of 3 million years. Results Divergence time estimates suggest that Bolitoglossa arrived in South America from Central America by at least the Early Miocene, ca. 23.6 MYA (95% HPD 15.9-30.3 MYA), and subsequently diversified. South American salamanders of the genus Bolitoglossa show strong phylogeographic structure at fine geographic scales and deep divergences at the mitochondrial gene cytochrome b (Cytb) and high diversity at the nuclear recombination activating gene-1 (Rag1). Species often contain multiple genetically divergent lineages that are occasionally geographically overlapping. Single specimens from two southeastern localities in Ecuador are sister to the equatoriana-peruviana clade and genetically distinct from all other species investigated to date. Another single exemplar from the Andes of northwestern Ecuador is highly divergent from all other specimens and is sister to all newly studied samples. Nevertheless, all sampled species of South American Bolitoglossa are members of a single clade that is one of several constituting the subgenus Eladinea, one of seven subgenera in this large genus. Conclusions The ancestors of South American salamanders likely arrived at least by the Early Miocene, well before the completion of the Late Pliocene Panamanian land bridge (widely accepted as ca. 3 MYA). This date is in agreement with recent, controversial, arguments that an older, perhaps short-lived, land connection may have existed between South America and present-day Panama 23–25 MYA. Since its arrival in South America, Bolitoglossa has diversified more extensively than previously presumed and currently includes several cryptic species within a relatively small geographic area. Rather than two upper Amazonian species currently recorded for this region, we propose that at least eight should be recognized, although these additional lineages remain to be formally described. PMID:23497060

2013-01-01

248

Evolution of a Miocene sag basin in the Alboran Sea  

NASA Astrophysics Data System (ADS)

The Alboran domain represents the westernmost termination of the peri-Mediterranean Alpine orogen. Its arcuate shape, delimited to the North by the Betic range and to the South by the Rif range, is the result of subduction, collision and slab migration processes. During the Neogene, several sedimentary basins formed on the Betics metamorphic basement, mainly due to the extensional collapse of the previously thickened crust of the Betic-Rif belt. The major sedimentary depocentre, the Western Alboran Basin (WAB), is surrounded by the Gibraltar arc, the volcanic Djibouti mounts and the Alboran ridge, and is partly affected by shale tectonics and associated mud volcanism. High-quality 2-D seismic profiles acquired along the Moroccan margin during the last decade reveal a complete history of the basin. Our study deals with the analysis of seismic profiles oriented parallel and orthogonal to the Mediterranean Moroccan margin. The stratigraphy was calibrated using well data from offshore Spain and Morocco. Our study focuses particularly on the tectono-stratigraphic reconstruction of the basin. The formation of the WAB began in the Early Miocene (Aquitanian - Burdigalian). A massive unit of Early Miocene to Lower Langhian shales and olistostromes forms a thick mobile décollement layer that controls and accommodates deformation of the basin fill. From the Upper Langhian to the Upper Tortonian, the basin is filled by a thick sequence of siliciclastic deposits. Stratigraphic geometries identified on seismic data clearly indicate that deformation of the basin fill started during deposition of Upper Langhian to the Upper Tortonian clastics. Shale tectonic deformation was re-activated recently, during the Messinian desiccation of the Mediterranean Sea (and the following catastrophic Pliocene reflooding) or during the Quaternary contourite deposition The sedimentary layers gently dip towards the basin centre and "onlaps" onto the basin margin, especially onto the basement high that bounds the basin toward the East. The contacts observed between the sediment and the basement reflectors are purely stratigraphic. These observations confirm that the geometry is essentially that of a sag basin. We discuss all these stratigraphic observations in the scope of the geodynamic evolution of the eastern and western Alboran basin and the extension recorded onshore during the basin development time interval.

Do Couto, D.; Gorini, C.; Jolivet, L.; Letouzey, J.; Smit, J.; d'Acremont, E.; Auxietre, J. L.; Le Pourhiet, L.; Estrada, F.; Elabassi, M.; Ammar, A.; Jabour, H.; Vendeville, B.

2012-04-01

249

The record of Miocene impacts in the Argentine Pampas  

NASA Astrophysics Data System (ADS)

Argentine Pampean sediments represent a nearly continuous record of deposition since the late Miocene (˜10 Ma). Previous studies described five localized concentrations of vesicular impact glasses from the Holocene to late Pliocene. Two more occurrences from the late Miocene are reported here: one near Chasicó (CH) with an 40Ar/39Ar age of 9.24 ± 0.09 Ma, and the other near Bahía Blanca (BB) with an age of 5.28 ± 0.04 Ma. In contrast with andesitic and dacitic impact glasses from other localities in the Pampas, the CH and BB glasses are more mafic. They also exhibit higher degrees of melting with relatively few xenoycrysts but extensive quench crystals. In addition to evidence for extreme heating (>1700 °C), shock features are observed (e.g., planar deformation features [PDFs] and diaplectic quartz and feldspar) in impact glasses from both deposits. Geochemical analyses reveal unusually high levels of Ba (˜7700 ppm) in some samples, which is consistent with an interpretation that these impacts excavated marine sequences known to be at depth. These two new impact glass occurrences raise to seven the number of late Cenozoic impacts for which there is evidence preserved in the Pampean sediments. This seemingly high number of significant impacts over a 106 km2 area in a time span of 10 Myr is consistent with the number of bolides larger than 100 m expected to enter the atmosphere but is contrary to calculated survival rates following atmospheric disruption. The Pampean record suggests, therefore, that either atmospheric entry models need to be reconsidered or that the Earth has received an enhanced flux of impactors during portions of the late Cenozoic. Evidence for the resulting collisions may be best preserved and revealed in rare dissected regions of continuous, low-energy deposition such as the Pampas. Additionally, the rare earth element (REE) concentrations of the target sediments and impact melts associated with the Chasicó event resemble the HNa/K australites of similar age. This suggests the possibility that those enigmatic tektites could have originated as high-angle, distal ejecta from an impact in Argentina, thereby accounting for their rarity and notable chemical and physical differences from other Australasian impact glasses.

Schultz, Peter H.; Zárate, Marcelo; Hames, Willis E.; Harris, R. Scott; Bunch, T. E.; Koeberl, Christian; Renne, Paul; Wittke, James

2006-05-01

250

Resource partitioning among top predators in a Miocene food web  

PubMed Central

The exceptional fossil sites of Cerro de los Batallones (Madrid Basin, Spain) contain abundant remains of Late Miocene mammals. From these fossil assemblages, we have inferred diet, resource partitioning and habitat of three sympatric carnivorous mammals based on stable isotopes. The carnivorans include three apex predators: two sabre-toothed cats (Felidae) and a bear dog (Amphicyonidae). Herbivore and carnivore carbon isotope (?13C) values from tooth enamel imply the presence of a woodland ecosystem dominated by C3 plants. ?13C values and mixing-model analyses suggest that the two sabre-toothed cats, one the size of a leopard and the other the size of a tiger, consumed herbivores with similar ?13C values from a more wooded portion of the ecosystem. The two sabre-toothed cats probably hunted prey of different body sizes, and the smaller species could have used tree cover to avoid encounters with the larger felid. For the bear dog, ?13C values are higher and differ significantly from those of the sabre-toothed cats, suggesting a diet that includes prey from more open woodland. Coexistence of the sabre-toothed cats and the bear dog was likely facilitated by prey capture in different portions of the habitat. This study demonstrates the utility of stable isotope analysis for investigating the behaviour and ecology of members of past carnivoran guilds. PMID:23135673

Domingo, M. Soledad; Domingo, Laura; Badgley, Catherine; Sanisidro, Oscar; Morales, Jorge

2013-01-01

251

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

USGS Publications Warehouse

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.

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

1998-01-01

252

Porosity evolution of upper Miocene reefs, Almeria Province, Southern Spain  

SciTech Connect

In the reef cores and fore-reef breccia beds, porosity in both primary and postdepositional. Primary porosity is of three types: (a) boring clam holes in the scleractinian coral heads, cemented reef rocks, and breccias; (b) intraparticle porosity within the corals, Halimeda plates, and vermetid worm tubes; and (c) interparticle porosity between bioclastic fragments and in the reef breccia. Postdepositional moldic porosity was formed by the solution of aragonitic material such as molluscan and coral fragments. The Polomo reef carbonate rocks have high porosity and permeability, and retain a great amount of depositional porosity. Pores range in size from a few micrometers to 30 cm. The extensive intercrystalline porosity and high permeability resulted from dolomitization of micritic matrix. Some porosity reduction has occured by incomplete and partial sparry calcite infilling of interparticular, moldic, and intercrystalline voids. The high porosity and permeability of these reefs make them important targets for petroleum exploration in the western Mediterranean off southern Spain. In these offshore areas in the subsuface the volcanic ridge and the Plomo reef complex are locally onlapped or overlapped by 350 m or more of Miocene and Pliocene fine-grained sedimentary rocks. The possibility exists that the buried Plomo reef deposits may form traps for oil and gas in the offshore areas southwest of the type locality. Stratigraphic traps also may occur where the Neogene sequence above the Plomo reef complex onlaps the volcanic ridge. 17 figures.

Armstrong, A.K.; Snavely, P.D. Jr.; Addicott, W.O.

1980-02-01

253

Resource partitioning among top predators in a Miocene food web.  

PubMed

The exceptional fossil sites of Cerro de los Batallones (Madrid Basin, Spain) contain abundant remains of Late Miocene mammals. From these fossil assemblages, we have inferred diet, resource partitioning and habitat of three sympatric carnivorous mammals based on stable isotopes. The carnivorans include three apex predators: two sabre-toothed cats (Felidae) and a bear dog (Amphicyonidae). Herbivore and carnivore carbon isotope (?(13)C) values from tooth enamel imply the presence of a woodland ecosystem dominated by C(3) plants. ?(13)C values and mixing-model analyses suggest that the two sabre-toothed cats, one the size of a leopard and the other the size of a tiger, consumed herbivores with similar ?(13)C values from a more wooded portion of the ecosystem. The two sabre-toothed cats probably hunted prey of different body sizes, and the smaller species could have used tree cover to avoid encounters with the larger felid. For the bear dog, ?(13)C values are higher and differ significantly from those of the sabre-toothed cats, suggesting a diet that includes prey from more open woodland. Coexistence of the sabre-toothed cats and the bear dog was likely facilitated by prey capture in different portions of the habitat. This study demonstrates the utility of stable isotope analysis for investigating the behaviour and ecology of members of past carnivoran guilds. PMID:23135673

Domingo, M Soledad; Domingo, Laura; Badgley, Catherine; Sanisidro, Oscar; Morales, Jorge

2013-01-01

254

Hydrologic cycling over Antarctica during the middle Miocene warming  

NASA Astrophysics Data System (ADS)

From 20 to 15 million years (Myr) ago, a period of global warmth reversed the previous ice growth on Antarctica, leading to the retreat of the West Antarctic Ice Sheet and the contraction of the East Antarctic Ice Sheet. Pollen recovered from the Antarctic shelf indicates the presence of substantial vegetation on the margins of Antarctica 15.7Myr ago. However, the hydrologic regime that supported this vegetation is unclear. Here we combine leaf-wax hydrogen isotopes and pollen assemblages from Ross Sea sediments with model simulations to reconstruct vegetation, precipitation and temperature in Antarctica during the middle Miocene. Average leaf-wax stable hydrogen isotope (?D) values from 20 to 15.5Myr ago translate to average ?D values of -50‰ for precipitation at the margins of Antarctica, higher than modern values. We find that vegetation persisted from 20 to 15.5Myr ago, with peak expansions 16.4 and 15.7Myr ago coinciding with peak global warmth and vegetation growth. Our model experiments are consistent with a local moisture source in the Southern Ocean. Combining proxy measurements with climate simulations, we conclude that summer temperatures were about 11°C warmer than today, and that there was a substantial increase in moisture delivery to the Antarctic coast.

Feakins, Sarah J.; Warny, Sophie; Lee, Jung-Eun

2012-08-01

255

The biostratigraphic basis for Gulf Coast Miocene sequence stratigraphy  

SciTech Connect

A chronostratigraphic framework was developed as a prelude to a regional sequence stratigraphic and associated systems tracts analysis of the offshore Louisiana and Texas Miocene. The integrated data base for this study included over 10,000 line mi of seismic data, 230 wireline logs, and detailed biostratigraphic analyses on 35 wells. The objective of the study was to map systems tracts and facies that may help delineate prospective areas. Because they are a fundamental stratigraphic unit within a sequence, this framework emphasizes condensed sections and their calibration by microfossil highest occurrence datums. Condensed sections have been delineated utilizing planktonic foraminiferal and calcareous nannofossil abundance and species diversity patterns, as well as detailed paleo-water depth determinations based on benthic foraminiferal biofacies. Pitfalls in the use of condensed sections may arise in shallow paleoshelf settings where datums may be unreliable, and in deeper environments where multiple abundance/diversity peaks may occur. However, an event stratigraphic scheme is generally the most satisfactory method for overcoming correlation problems inherent in the Gulf Coast unstable prograding shelf margin.

Shaffer, B.L.; Pacht, J.A.; Bowen, B.E. (Calibre Consulting Services, Inc., Houston, TX (United States))

1991-03-01

256

The rainbow range, British Columbia: A miocene peralkaline shield volcano  

NASA Astrophysics Data System (ADS)

The Rainbow Range is a Late Miocene shield volcano (30 km diameter, 370 km 3) whose stratiform flanks surround a complex central zone. Over a 2-m.y. interval, extrusion of low viscosity, silicic peralkaline lavas and minor basaltic lavas built up the gently sloping (5-8°) flanks, forming a shield volcano rather than a composite cone. Comenditic trachytes are the lowest flows exposed on the north flank of the volcano. Thin mugearite flows rest unconformably on the comenditic trachytes. Comendites unconformably overlie the mugearites and account for at least 75% of the volume of flows within the flank zone. These lavas are distinguished from the comenditic trachytes by lower Al 2O 3 (13%), higher total iron as Fe 2O 3, (7%), and extremely depleted Sr (1-10 ppm) and Ba (10-100 ppm). Strontium isotopic studies combined with petrologic data suggest that Rainbow Range lavas originated from alkali basalt magma trapped in an intracrustal magma chamber and tapped at several intervals after it underwent crystal fractionation. A best-fit mathematical model for the origin of the suite involves step-wise derivation of the lavas in the order hawaiite ? mugeartite ? comenditic trachyte ? comendite, with the major phases precipitating in the order: olivine, clinopyroxene, plagioclase, iron-titanium oxides, and alkali feldspar.

Bevier, Mary Lou

1981-12-01

257

Apatite fission-track data for the Miocene Arabia-Eurasia collision  

NASA Astrophysics Data System (ADS)

The collision between the Eurasian and Arabian plates along the 2400-km-long Bitlis-Zagros thrust zone isolated the Mediterranean from the Indian Ocean and has been linked to extension of the Aegean, rifting of the Red Sea, and the formation of the North and East Anatolian fault systems. However, the timing of the collision is poorly constrained, and estimates range from Late Cretaceous to late Miocene. Here, we report the first apatite fission track (AFT) ages from the Bitlis-Zagros thrust zone. The AFT samples are distributed over the 450 km length of the Bitlis thrust zone in southeast Turkey and include metamorphic rocks and Eocene sandstones. Despite the disparate lithology and large distance, the AFT ages point consistently to exhumation in the Early to Mid Miocene between 18 and 13 Ma. Tectonostratigraphic analysis of sedimentary successions along the facing converging margins of the Arabian and Eurasian plates can provide additional constraints on the timing of collision. Along the northern margin of the Arabian plate in southeast Anatolia, widespread shallow-marine carbonate deposition during the Eocene was followed by an Oligocene regression, and Oligocene deposits are missing over much of the region. A marine transgression at the beginning of the Miocene led to the deposition of Lower Miocene (Aquitanian-Burdigalian) reefal carbonates, which crop out close to the Bitlis thrust zone. The carbonates pass upward and northward to siliciclastic marine turbidites, again of Lower Miocene age. The turbidites, which are 800 m thick, were deposited in a peripheral foreland basin during its phase of underfilling and are at present partly overthrust by the Bitlis Massif and the Eocene series. The Lower Miocene series represent the last marine sequence on the northern margin of the Arabian plate and are followed by the deposition of continental conglomerate, sandstone and evaporites of late Miocene-Pliocene age. North of the Bitlis suture in the eastern Anatolia on the Eurasian plate, a thick succession of Oligocene turbidites crops out north of Mu?; these are overlain by shallow marine sandstone, shale, and limestone of early Miocene (Aquitanian-Burdigalian) age. The Oligocene-Miocene succession was deposited in a retroarc foreland basin associated with northward subduction of the Arabian plate. Lower Miocene (Lower Burdigalian) shallow-marine limestones also crop out widely west of Lake Van, where they are unconformably overlain by Pliocene to Holocene volcanic rocks. The AFT ages, along with an appraisal of regional stratigraphy, indicate that the last oceanic lithosphere between the Arabian and Eurasian plates was consumed by the early Miocene (ca. 20 Ma). The early to mid-Miocene Arabia-Eurasia collision supports a temporal link between collision and the formation of the late Miocene North Anatolian fault. However, extension in the Aegean domain, related to the slab retreat, dates back to the Oligocene. This and the recent recognition of major Oligocene dextral strike-slip faults in Anatolia suggest that the westward translation of Anatolia started in the Oligocene and predated the Miocene Arabia-Eurasia collision.

Okay, Aral; Zattin, Massimiliano; Cavazza, William

2010-05-01

258

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

PubMed Central

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

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

2000-01-01

259

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

SciTech Connect

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.

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

1989-09-01

260

Middle Miocene Hominoids dispersion and radiation: impact of climate and vegetation changes in Europe  

NASA Astrophysics Data System (ADS)

The middle Miocene is a time of important climatic changes, and a crucial period for ape's evolution. The Middle Miocene Climatic Optimum (MMCO), that occurred approximately 17 to 15 Ma, was one of the last global warming event of the Cenozoic. This period also corresponds to the first dispersion of apes from Africa to Europe, which was made possible by tectonic and environmental changes, in particular the expansion of hominoids habitat: (sub-)tropical forest. Following the MMCO, an abrupt global cooling occurred that coincides with an important radiation of European hominoids. The most common view is that the widening of hominoids habitat during the MMCO was the main factor of their dispersion from Africa to Europe. Moreover, the major climatic change that followed induced an opening of the environment because of cooler and dryer conditions, which should have lead to a fragmentation of hominoids' habitat. This imply that hominoids evolved separately in refuges during the end of the Miocene, so the radiation observed in the fossil record of European Miocene apes is interpreted as a divergent evolution in a fragmented habitat. However, no study has yet demonstrated this evolutionary scenario. Our aim is to study the environmental changes during the middle Miocene, in particular climate and vegetation changes, and to link them with these two major events of hominoids' evolution. Using climate and vegetation models, we investigate the role of environmental variation in hominoids' evolution during the middle Miocene, in particular between 17 and 14 Ma. We perform two climatic experiments (16Ma and 14Ma) with the atmospheric general circulation model LMDZ. The results of these experiments will then be used to force the dynamic vegetation model CARAIB. This should help us to simulate hominoids' habitat for the two time period chosen, and to discuss the role of important climate change for Miocene apes evolution.

Hamon, N.; Sepulchre, P.; Contoux, C.; Jaeger, J.-J.; Ramstein, G.

2012-04-01

261

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

SciTech Connect

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.

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

1996-01-01

262

Provenance of the lower Miocene of the Gulf of Mexico from detrital zircon double dating  

NASA Astrophysics Data System (ADS)

The lower Miocene interval of the Gulf of Mexico (GOM) has recently gained increasing attention from oil and gas industry due to its hydrocarbon potential below the salt canopy. However, it has been less well studied than both the underlying Oligocene and overlying middle Miocene strata. The lower Miocene worldwide is a transitional period of tectonic, climatic, and oceanographic change. In particular, it is a period of major tectonic reorganization in the western interior of North America (Rocky Mountains), involving a shift from the Oligocene thermal phase, with abundant volcanic activity recorded in the thick Frio/Vicksburg succession of the GOM, to the Miocene Basin-Range extensional phase. Climatic conditions also changed from a relatively arid Oligocene to wetter Miocene, resulting in increased sediment yields from exhumed tectonic structures. Previous provenance studies used proportions of quartz, feldspar and lithic fragments and consideration of likely river courses through known paleogeomorphological elements. Only limited detrital zircon (DZ) U-Pb studies on Paleocene strata have been undertaken and there has been no previous U-Pb and (U-Th)/He double dating in the GOM. In this study we apply the latest analytical approaches, such as DZ U-Pb dating to gain robust source terranes ages and more fully elucidate the complex sediment provenance and dispersal history of GOM. We also employ DZ (U-Th)/He (ZHe) dating, combined with DZ U-Pb, to not only define sedimentary provenance but also the exhumation histories of detrital source regions. Samples of lower Miocene outcrop exposures in Texas and Louisiana have been collected to discriminate the varied tectonic and drainage system changes across the basin in lateral. In addition, samples from the Eocene, Oligocene and middle Miocene have been obtained to reveal vertical shift of source terranes contributions. Our initial age data show detrital zircons of lower Miocene sediments come from a wide range of source terranes including a large populations from the western interior of North America (Rocky Mountains), Grenville, Mid-Continent, and Yavapai-Mazatzal provinces, with smaller populations from the Appalachian-Ouachita, Wyoming or Superior regions. Based on U-Pb dating results, we will carry out (U-Th)/He dating on selected zircons to reveal the detailed exhumation histories of the sediment source regions. Using the dual criteria of DZ crystallization age (U-Pb) and cooling age (U-Th/He) to constrain provenance will enable us to generate rigorous reconstructions of the lower Miocene depositional systems from source terrane to deep-water sink for this key transitional period in geologic history.

xu, J.

2013-12-01

263

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

NASA Astrophysics Data System (ADS)

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.

Rojay, Bora; Özsay?n, Erman

2013-04-01

264

A fish assemblage from an early Miocene horizon from Jabal Zaltan, Libya  

NASA Astrophysics Data System (ADS)

Recent excavations and prospecting in the early to middle Miocene deposits of the Maradah Formation in Jabal Zaltan, Libya, yielded a diverse fish assemblage coming from an early Miocene locality. The material described here includes more than 18 marine and freshwater taxa most of which were previously unreported from the area. Jabal Zaltan is one of the very few early Miocene Afroarabian fossil sites that produced such a diverse fish sample. Therefore, the fossils described here provide a unique insight into the composition of the early Miocene fish faunas from the northern African coast; a critical time period for faunas of the continent, as contact with Eurasia ended 100 million years of African isolation. In addition, the Jabal Zaltan fossils help consolidate the validity of Galeocerdo mayumbensis and extend its geographic range to include the Tethys. The Maradah deposits also host the first occurrences of two genera (Pteromylaeus, Distichodus) in the fossil record. The fish finds support the presumed depositional environment that of tropical shallow estuarine to deltaic conditions, and the freshwater fishes document the presence of a modern-type Nilosudanian fauna containing elements with both African and Asian affinities. The Jabal Zaltan ichthyofauna, with its diversity of taxa, has the potential to become a key reference fauna for future studies of early Miocene African fishes.

Argyriou, Thodoris; Cook, Todd D.; Muftah, Ahmed M.; Pavlakis, Paris; Boaz, Noel T.; Murray, Alison M.

2015-02-01

265

Strong winter monsoon wind causes surface cooling over India and China in the Late Miocene  

NASA Astrophysics Data System (ADS)

Modern Asian winter monsoon characterised by the strong northwesterly wind in East Asia and northeasterly wind in South Asia, has a great impact on the surface temperature of the Asian continent. Its outbreak can result in significant cooling of the monsoon region. However, it is still unclear whether such an impact existed and is detectable in the deep past. In this study, we use temperature reconstructions from plant and mammal fossil data together with climate model results to examine the co-evolution of surface temperature and winter monsoon in the Late Miocene (11-5 Ma), when a significant change of the Asian monsoon system occurred. We find that a stronger-than-present winter monsoon wind might have existed in the Late Miocene due to the lower Asian orography, particularly the northern Tibetan Plateau and the mountains north of it. This can lead to a pronounced cooling in southern China and northern India, which counteracts the generally warmer conditions in the Late Miocene compared to present. The Late Miocene strong winter monsoon was characterised by a marked westerly component and primarily caused by a pressure anomaly between the Tibetan Plateau and Northern Eurasia, rather than by the gradient between the Siberian High and the Aleutian Low. As a result, the close association of surface temperature with winter monsoon strength on inter-annual scale as observed at present may not have established in the Late Miocene.

Tang, H.; Eronen, J. T.; Kaakinen, A.; Utescher, T.; Ahrens, B.; Fortelius, M.

2015-01-01

266

Molluscan evidence for early middle Miocene marine glaciation in southern Alaska  

USGS Publications Warehouse

Profound cooling of Miocene marine climates in southern Alaska culminated in early middle Miocene coastal marine glaciation in the northeastern Gulf of Alaska. This climatic change resulted from interaction of the Yakutat terrane with southern Alaska beginning in late Oligocene time. The ensuing extreme uplift of the coastal Chugach and St. Elias Mountains resulted in progressive regional cooling that culminated in coastal marine glaciation beginning in the early middle Miocene (15-16 Ma) and continuing to the present. The counterclockwise flow of surface water from the frigid northeastern Gulf of Alaska resulted in a cold-temperate shallow-marine environment in the western Gulf of Alaska, as it does today. Ironically, dating of Gulf of Alaska marine glaciation as early middle Miocene is strongly reinforced by the presence of a few tropical and subtropical mollusks in western Gulf of Alaska faunas. Shallow-marine waters throughout the Gulf of Alaska were cold-temperate to cold in the early middle Miocene, when the world ocean was undergoing peak Neogene warming. -Author

Marincovich, L., Jr.

1990-01-01

267

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

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

268

Tectonic implications of early Miocene volcanic rocks, San Joaquin basin  

SciTech Connect

The early Miocene (22 Ma) Tecuya volcanic rocks of the San Emigdio Mountains were erupted during a regional episode of crustal extension in coastal California. These rocks are correlative with similar rocks in outcrops and the subsurface over at least 800 kmz in the southern San Joaquin basin. Initial dacitic eruptions produced laterally continuous subaerial to submarine pyroclastic flows. These facies rapidly buried alluvial fan deposits of the lower Tecuya Formation and marine sandstone of the Temblor Formation farther west. Following dacitic volcanism, massive basalt was deposited subaerially along the southeastern basin margin. Farther west, the basalt triples in thickness across synvolcanic, high-angle faults and consists of hyaloclastite and submarine basalt flows. Facies associations, thickness and tectural trends, and paleodispersal directions of the volcanic rocks were controlled by synvolcanic extensional faulting throughout the southern San Joaquin basin. The regional extent of these volcanic rocks provides an important chronostratigraphic marker and potential stratigraphic trap in a variety of depositional settings, from nonmarine to outer shelf and slope. Preliminary rare-earth element data indicate that both dacites and basalts exhibit LREE enrichment patterns. The {epsilon}{sub Nd}(O) values cluster around +3. Although these data are typical of island arc volcanic rocks, geological data clearly indicate that the Tecuya volcanic rocks were erupted in an extensional tectonic setting near the continental margin. Some other model, perhaps involving crustal contamination of magmas produced along the subducted East Pacific Rise, followed by syntectonic eruption along normal faults, is needed to explain this enigmatic combination of geochemical and geological data.

Cole, R.B.; Decelles, P.G. (Univ. of Rochester, NY (USA))

1990-05-01

269

Miocene/pliocene boundary and the terminal flood  

SciTech Connect

The boundary stratotype for the Miocene/Pliocene boundary, located at Capo Rosello, Sicily, occurs at a distinct lithostratigraphic change from Messinian evaporites to Zanclean open-marine sediments. Because bio- and magnetostratographic correlations of the stratotype with deep-sea sections have proven difficult, the authors propose to use strontium- and oxygen-isotope stratigraphies to correlate the earliest Pliocene at Capo Rosello with a marine sequence from the South Atlantic, DSDP Site 519. The Sr-isotope value of the sediments increases progressively between 6 and 4 Ma from approximately 0.708895 to 0.709026 with the M/P boundary at about 0.708948. Three cycles of rapid O-isotope fluctuations of 1.2 per thousand were recorded in the planktic forams between 5.10 and 4.96 Ma, which have been interpreted as an indication of unstable surface-current patterns related to a destabilization of the Antarctic ice sheet. The lowermost 11 m of the earliest Pliocene Trubi Fm. at Capo Rosello contains the MP1-1 and lowermost part of the MP1-2 zones and have an average Sr-isotope value of 0.708968, correlating them with the earliest Pliocene of Site 519. The sequence also contains 3 planktic cycles of O-isotope fluctuations of about 1.0 per thousands, which the authors correlate with the Site 519 cycles and interpret as global warmings and coolings related to climatic instability. They conclude that the terminal flooding of the Mediterranean at the M/P boundary resulted in global climatic disturbances possibly associated with a reorganization of oceanic circulation due to the renewed injection of Mediterranean bottom waters into the Atlantic Ocean.

McKenzie, J.A.; Mueller, P.; Mueller, D.

1985-01-01

270

HPLC determination of five polyphenols in rat plasma after intravenous administration of hawthorn leaves extract and its application to pharmacokinetic study.  

PubMed

A simple and specific HPLC-UV method was developed to simultaneously determine five active compounds including vitexin-4"-O-glucoside (VG), vitexin-2"-O-rhamnoside (VR), vitexin (VIT), rutin (RUT) and hyperoside (HP) in rat plasma after intravenous administrating the hawthorn leaves extract (HLE). With baicalin as internal standard (I.S.), sample pretreatment involved a one-step extraction with methanol of 0.2 ml plasma. The HPLC assay was carried out using a Phenomsil C18 analytical column with UV detection at 332 nm. The mobile phase consisted of methanol-acetonitrile-tetrahydrofuran-1% glacial acetic acid (6:1.5:18.5:74, v/v/v/v). The calibration curves were liner over the range of 2.030-500.5, 0.1513-75.64, 0.2507-12.54, 0.5128-25.64 and 0.4032-20.16 µg/ml for VG, VR, VIT, RUT and HP, respectively. The relative standard deviations (RSD) of the intra- and inter-day precisions for the analysis of the five analytes were between 1.0 and 8.9% with accuracies (relative error) below 8.2% for the analysis of the five analytes. The average extraction recoveries of five analytes were more than 82.67 ± 4.74%. The HPLC method herein described was fully validated and successfully applied to the pharmacokinetic studies after intravenous administration of HLE solution to rats over three doses. PMID:21048422

Wang, Si-Yuan; Chai, Ji-Yan; Zhang, Wen-Jie; Liu, Xun; DU, Yang; Cheng, Zhong-Zhe; Ying, Xi-Xiang; Kang, Ting-Guo

2010-11-01

271

Petrology of Ti Point Group, Northland, New Zealand  

Microsoft Academic Search

Lavas of the late Miocene Ti Point Group are found as scattered flow remnants, a dike, and a sill. Most are basalts with olivine phenocrysts set in a groundmass of clinopyroxene and plagioclase. One flow remnant is a glassy andesite and the relationship of this rock to the basalts is unknown. Together they are interpreted as the remains of a

R. F. Heming

1980-01-01

272

A new Early/Middle Miocene mammal locality from Macedonia, Greece  

NASA Astrophysics Data System (ADS)

A new fossiliferous locality with macro- and micro-mammals was found near the village of Agios Antonios, about 26 km southeast of Thessaloniki, Macedonia, Greece. The fossils are recovered from the fissure fillings of the karstified Mesozoic limestones of the basement. The fissures were filled in and covered by the clastic sediments of Antonios Fm, representing the first Neogene deposits of the Axios-Thermaikos Neogene palaeobasin. The age of the fauna indicates a time span from the end of the Early Miocene to the beginning of the Middle Miocene (upper part of MN 4 to lower part of MN 5). The deposition of Antonios Fm must have started during or a little earlier than the end of the Early Miocene, and consequently the Neogene Axios-Thermaikos palaeobasin was created during this time or a little earlier.

Koufos, George D.; Syrides, George E.

1997-10-01

273

Mixed carbonate-siliciclastic sedimentation on a Miocene fault-block, Gulf of Suez, Egypt  

NASA Astrophysics Data System (ADS)

The Miocene sediments at Abu Shaar (Red Sea, Egypt) include both carbonates and detrital silicates whose distribution is closely related to a pre-Miocene basement fault-block. As such, they demonstrate the relationships between local distensional tectonics and sedimentation. Because of the vertical bathymetric relief of the basement block, the carbonates include both a spectacular talus and massive platform facies. In spite of the presence of scattered corals, sedimentation is not truly reefal as deposits consist essentially of muddy bioclastic and silicate sands. The most typical ecological elements are numerous spectacular stromatolites. Rigidity of the sedimentary mass was mainly induced by early marine cementation. Carbonate-siliciclastic transitions on and around the Abu Shaar platform were determined mainly by basement morphology and related pre-Miocene tectonics.

El Haddad, A.; Aissaoui, D. M.; Soliman, M. A.

1984-01-01

274

A new species of Shaanxispira (Bovidae, Artiodactyla) from the upper Miocene of China.  

PubMed

A new species of the bovid Shaanxispira, from the upper Miocene deposits of the Linxia Basin, Gansu Province, China, is described here. Shaanxispira is endemic to Northern China and was previously known only from the Lantian area, Shaanxi Province, by two species, S. chowi and S. baheensis. The new species, S. linxiaensis nov. sp., is of early Bahean in age, slightly older than the species from the Lantian area. The horn-cores of the new species are more derived, with large wing-shaped antero-medial keels, suggesting the occurrence of a different lineage of Shaanxispira in the Linxia Basin. Although Shaanxispira has homonymously twisted horn-cores, it is not closely related to other late Miocene bovids with homonymously twisted horn-cores, like Oioceros and Samotragus. Its phylogenetic status is still in debate, but might be more closely related to the late Miocene "ovibovines."  PMID:24870338

Shi, Qinqin; He, Wen; Chen, Shanqin

2014-01-01

275

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

SciTech Connect

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.

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

276

Miocene and Pliocene dominated diversification of the lichen-forming fungal genus Melanohalea (Parmeliaceae, Ascomycota) and Pleistocene population expansions  

PubMed Central

Background Factors promoting diversification in lichen symbioses remain largely unexplored. While Pleistocene events have been important for driving diversification and affecting distributions in many groups, recent estimates suggest that major radiations within some genera in the largest clade of macrolichens (Parmeliaceae, Ascomycota) vastly predate the Pleistocene. To better understand the temporal placement and sequence of diversification events in lichens, we estimated divergence times in a common lichen-forming fungal genus, Melanohalea, in the Northern Hemisphere. Divergence times were estimated using both concatenated gene tree and coalescent-based multilocus species tree approaches to assess the temporal context of major radiation events within Melanohalea. In order to complement our understanding of processes impacting genetic differentiation, we also evaluated the effects of Pleistocene glacial cycles on population demographics of distinct Melanohalea lineages, differing in reproductive strategies. Results We found that divergence estimates, from both concatenated gene tree and coalescent-based multilocus species tree approaches, suggest that diversification within Melanohalea occurred predominantly during the Miocene and Pliocene, although estimated of divergence times differed by up to 8.3 million years between the two methods. These results indicate that, in some cases, taxonomically diagnostic characters may be maintained among divergent lineages for millions of years. In other cases, similar phenotypic characters among non-sister taxa, including reproductive strategies, suggest the potential for convergent evolution due to similar selective pressures among distinct lineages. Our analyses provide evidence of population expansions predating the last glacial maximum in the sampled lineages. These results suggest that Pleistocene glaciations were not inherently unfavorable or restrictive for some Melanohalea species, albeit with apparently different demographic histories between sexually and vegetatively reproducing lineages. Conclusions Our results contribute to the understanding of how major changes during the Miocene and Pliocene have been important in promoting diversification within common lichen-forming fungi in the northern Hemisphere. Additionally, we provide evidence that glacial oscillations have influenced current population structure of broadly distributed lichenized fungal species throughout the Holarctic. PMID:22963132

2012-01-01

277

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

E-print Network

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

Paris-Sud XI, Université de

278

The Miocene Tepoztlan Formation (Central Mexico) - Key to a Better Understanding of the Initial Phase of the Transmexican Volcanic Belt  

Microsoft Academic Search

In Miocene times, a major volcano-tectonic change took place in West and Central Mexico due to a reorganization of the tectonic plates in the western Pacific region. Since the mid-Miocene, the Transmexican Volcanic Belt (TMVB) began to form. Until present, few data exist on its initial phase since older volcanic products of the TMVB are widely covered by young volcanic

N. Lenhardt; M. Hinderer; J. Hornung; I. Torres-Alvarado; H. Boehnel

2007-01-01

279

ELSEVIER Earth and Planetary Science Letters 128 (1994) 513-526 Magnetostratigraphic dating of the middle Miocene climate  

E-print Network

and marine records confirm and accurately date a global cooling event in the middle Miocene. The age of 14ELSEVIER Earth and Planetary Science Letters 128 (1994) 513-526 EPSL Magnetostratigraphic dating of the middle Miocene climate change in the continental deposits of the Aragonian type area in the Calatayud

Utrecht, Universiteit

280

The evolution of Miocene climates in North China: Preliminary results of quantitative reconstructions from plant fossil records  

Microsoft Academic Search

The Miocene climate evolution in North China is preliminarily discussed by means of comparisons in seven climate parameters quantitatively reconstructed by the Coexistence Approach on 34 selected macro- and microfloras over North China. The Miocene temperatures show no great difference in the western and eastern part of North China. Temperature fluctuations, particularly in mean annual temperature, are found within floras

Torsten Utescher; Zhekun Zhou; Bainian Sun

2011-01-01

281

14. EARLY TO MIDDLE MIOCENE SEQUENCES, SYSTEMS TRACTS, AND BENTHIC FORAMINIFERAL BIOFACIES, NEW JERSEY COASTAL PLAIN 1  

Microsoft Academic Search

We identified and dated nine lower to middle Miocene sequences at the Island Beach, Atlantic City, and Cape May, New Jersey boreholes, integrating Sr-isotopic, lithofacies, log, and benthic foraminiferal biofacies data in a sequence stratigraph ic framework. Miocene sequences typically shallow upsection, representing three major lithofacies: (1) thin, shelly, glauconite sands of the Transgressive Systems Tracts deposited in inner-middle (0-

Kenneth G. Miller; Scott Rufolo; Peter J. Sugarman; Stephen F. Pekar; James V. Browning; David W. Gwynn

282

Paleobiogeography of Miocene Equinae of North America: A phylogenetic biogeographic analysis of the relative roles of climate, vicariance, and dispersal  

E-print Network

, pers. communication 2007) (Fig. 1) and the fossil record of horses is densely sampled in North AmericaPaleobiogeography of Miocene Equinae of North America: A phylogenetic biogeographic analysis underwent a major radiation during the Miocene in North America, diversifying from one species, Parahippus

Barnosky, Anthony D.

283

Extreme weathering\\/erosion during the Miocene Climatic Optimum: Evidence from sediment record in the South China Sea  

Microsoft Academic Search

Investigating the interplay between continental weathering and erosion, climate, and atmospheric CO2 concentrations is significant in understanding the mechanisms that force the Cenozoic global cooling and predicting the future climatic and environmental response to increasing temperature and CO2 levels. The Miocene represents an ideal test case as it encompasses two distinct extreme climate periods, the Miocene Climatic Optimum (MCO) with

Shiming Wan; Wolfram M. Kürschner; Peter D. Clift; Anchun Li; Tiegang Li

2009-01-01

284

The evolution of pCO2, ice volume and climate during the middle Miocene  

NASA Astrophysics Data System (ADS)

The middle Miocene Climatic Optimum (17-15 Ma; MCO) is a period of global warmth and relatively high CO2 and is thought to be associated with a significant retreat of the Antarctic Ice Sheet (AIS). We present here a new planktic foraminiferal ?11B record from 16.6 to 11.8 Ma from two deep ocean sites currently in equilibrium with the atmosphere with respect to CO2. These new data demonstrate that the evolution of global climate during the middle Miocene (as reflected by changes in the cyrosphere) was well correlated to variations in the concentration of atmospheric CO2. What is more, within our sampling resolution (?1 sample per 300 kyr) there is no evidence of hysteresis in the response of ice volume to CO2 forcing during the middle Miocene, contrary to what is understood about the Antarctic Ice Sheet from ice sheet modelling studies. In agreement with previous data, we show that absolute levels of CO2 during the MCO were relatively modest (350-400 ppm) and levels either side of the MCO are similar or lower than the pre-industrial (200-260 ppm). These new data imply the presence of either a very dynamic AIS at relatively low CO2 during the middle Miocene or the advance and retreat of significant northern hemisphere ice. Recent drilling on the Antarctic margin and shore based studies indicate significant retreat and advance beyond the modern limits of the AIS did occur during the middle Miocene, but the complete loss of the AIS was unlikely. Consequently, it seems that ice volume and climate variations during the middle Miocene probably involved a more dynamic AIS than the modern but also some component of land-based ice in the northern hemisphere.

Foster, Gavin L.; Lear, Caroline H.; Rae, James W. B.

2012-08-01

285

K-Ar Geochronology of Igneous Amphibole Macrocrystals of Miocene to Pliocene Volcaniclastics, Styrian Basin, Austria  

NASA Astrophysics Data System (ADS)

The Styrian Basin basin is situated at the south-eastern margin of the Eastern Alps. Two basement highs separate the Styrian Basin in sub-basins: the Middle Styrian Basement High divides the shallower Western Styrian Basin (with ~800 m thick Neogene sediments) from the Eastern Styrian Basin (with a ~3000 m thick infill). A second, the South Burgenland Basement High, separates the West Pannonian from the Styrian Basin. The north-south trending Auersbach Basement Highseparates the Eastern Styrian basin in two sub-basins. The Eastern Styrian Basin hosts distinct volcanic depocentres represented by Miocene (Karpatian to Badenian) shield volcanoes and volcanic tuff intercalations situated within Badenian sediments. A second phase of basaltic volcanism has a Late Miocene to Pliocene age. The Western Styrian Basin hosts only one Middle Miocene volcano. Most of the Middle Miocene volcanics are covered by sediments and are known only from boreholes and geophysical studies. In this study, we present new K/Ar ages on amphibole phenocrysts of volcaniclastic rocks from the Styrian Basin, Austria, as well as from the adjoining areas. Beside Lower Miocene shield volcanoes and Pliocene effusive alkaline volcanic rocks the eastern Styrian Basin hosts a number of phreatomagmatic tuff occurrences. The tuffs contain the well known mantle xenoliths and frequent amphibole phenocrysts. The new age data indicate that the Late Miocene phreatomagmatic volcanism started in Pontian and ended in Romanian. The complete interval of the youngest volcanism in the Styrian Basin covers 6 Ma, similar to the volcanism of the western part of the Pannonian Basin and the Nógrád/Novohrad area (West Carpathian).

Bojar, Hans-Peter; Bojar, Ana-Voica; Ha?as, Stanis?aw; Wojtowicz, Arthur

2013-04-01

286

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

USGS Publications Warehouse

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.

Gibson, T.G.

1965-01-01

287

An environmental study of the subsurface Miocene of Brazoria and Galveston counties, Texas  

E-print Network

of the Middle Transitional nn. ". r arel (2) l!' an i t, ("-l ~R. , M t. io narine. Unit, (3) "3" narrier. (al relate) n~i. ni. aerie Unit. The distribution of Miocene sediments in Braroria end Galveston counties; Texas suggests that Miocene, seas were in a... facies anti (3) the upper 550 feet are cottpased of outs? berrit r sediments. l Tne ~lnn nice lne n: rto . IJntt Tnie entt jr nresent between -4275 en+ 4580 feet end ie 305 feet. thic'k. Regiments of this unit contain a "werc" marine facies. 3 The "P...

Linder, Henry Darrell

1962-01-01

288

A New Genus of Cricetid Rodent from the Hemingfordian (Miocene) of Nebraska  

E-print Network

. Paleontol., v. 44, p. 524-526. Lindsay, E.H., 1972, Small mammal fossils from the Barstow Formation, California: Univ. Calif. Publ. Geol. Sci., v.93, p. 1-104. Martin, JE., 1976, Small mammals from the Miocene Batesland Formation of South Dakota: Contrib... the lower Miocene Ger- ing Formation of western Nebraska: Occas. Pap. Mus. Nat. Hist., Univ. Kans.: v. 32, p. 1-12. 1980, The early evolution of the Cricetidae in North America: Univ. Kans. Paleontol. Contrib., Pap. 102, 42 p. Schultz, C.B., 1938...

Martin, Larry D.; Corner, R. G.

1980-10-10

289

Stratigraphical investigations on a new Miocene fossil-bearing sequence in Central Inner Mongolia, China  

NASA Astrophysics Data System (ADS)

Central Inner Mongolia has been an area of great paleontological interest since the beginning of the 20th century. Although the area has produced numerous diverse collections of Miocene faunas, fossil records from the early Miocene of Inner Mongolia are relatively rare. The localities occur mainly as scattered faunal horizons and their stratigraphy is challenging owing to lack of continuous vertical exposures. Consequently, most age estimations of these Miocene sites are based on paleontological evidence alone, with very few sites having been dated independently based on paleomagnetics. The Damiao site in Siziwang Qi, Inner Mongolia, was discovered in 2006, and during the following four years extensive field activities were undertaken. The focus was on paleontological studies and on the stratigraphy of the Neogene sediments. The field survey led to the recovery of approximately 30 new fossiliferous localities, which have produced a rich mammalian fauna, including pliopithecid remains. The bulk of the vertebrate fossils and localities have been recovered from three main fossil horizons. We have interpreted the Damiao sequence as the remains of a fluvio-lacustrine system comprising channels, subaerially exposed floodplains and ephemeral/marginal lacustrine environments. This study presents the litho- and magnetostratigraphy of the Damiao area and provides age estimations for the important fossil-bearing localities. The two local stratigraphic sections measured and sampled for paleomagnetic analysis coincide with important vertebrate fossil localities. The western section is about 30 m thick and includes fossil locality DM16 while the eastern section spans up 40 m and comprises localities DM01 and DM02. The paleomagnetic results and faunal evidence suggest a correlation in the magnetozones C6Ar through C5r with an age range of ca 21 to 11 Ma. The interval of reversed polarity at the base of the section (C6Ar) coincides with fossil locality DM16. The pliopithecid locality DM01 represents late middle Miocene and has an age estimate of about 12 Ma while the locality DM02 represents earliest late Miocene with an age estimate of about 11.6- 11.7 Ma. Our magnetostratigraphic results confirm that the Damiao strata constitute one of the most continuous sequences in Inner Mongolia with early, middle and late Miocene fossil faunas in stratigraphic superposition. The results also provide constraints on the paleoenvironmenal evolution and bioevents of the area. The occurrence of pliopithecid primates in the middle Miocene of Inner Mongolia suggests relatively humid habitats and challenges the scenarios suggesting arid and highly seasonal conditions for Central Asia since Early Miocene.

Kaakinen, Anu; Aziz, Hayfaa Abdul; Passey, Benjamin H.; Zhang, Zhaoqun; Liu, Liping; Krijgsman, Wout; Fortelius, Mikael

2014-05-01

290

11. PALYNOLOGICAL DELINEATION AND REGIONAL CORRELATION OF LOWER THROUGH UPPER MIOCENE SEQUENCES IN THE CAPE MAY AND ATLANTIC CITY BOREHOLES, NEW JERSEY COASTAL PLAIN1  

Microsoft Academic Search

Dinocyst and strontium isotopic stratigraphies from two boreholes are integrated to develop a fine chronology for the lower through upper Miocene succession in New Jersey. These results represent the best constrained and most detailed subdivision of New Jersey Miocene strata to date, including the first confirmed record of upper Miocene deposits in the New Jersey Coastal Plain. The latter is

Laurent de Verteuil

291

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

NASA Astrophysics Data System (ADS)

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.

Reynaud, Jean-Yves; James, Noël P.

2012-12-01

292

Paleomagnetism, rock magnetism, and PIXE Analysis of Oligocene-Miocene sediments (Bennett County, South Dakota)  

NASA Astrophysics Data System (ADS)

We present paleo- and rock magnetic results together with Particle Induced X-ray Emission (PIXE) data from an Oligocene-Miocene aged section in central South Dakota. Sediment samples recovered by the High-Plains Aquifer Drilling Program of the South Dakota Geological Survey retrieved well-preserved core material for paleomagnetic and geochemical analysis. A 250 m long core was retrieved from the Tertiary Arikaree Group, which consists predominantly of fine-grained sandstones and limestones with interbedded silt and clay. Paleomagnetic and rock magnetic measurements were carried out at 30 cm resolution on more than 200 discrete samples, and geochemical analysis using PIXE at the Louisiana Accelerator Center on twenty selected samples, with the goal of extracting a geomagnetic polarity time scale and to reconstruct paleoenvironmental conditions. Stepwise demagnetization of the natural remnant magnetization yields excellent to poor demagnetization behavior, with a viscous isothermal remnant magnetization drilling overprint effectively removed during the 20 mT demagnetization step. Paleomagnetic data are characterized by normal and reversed inclinations, consistent with the site position in South Dakota. Magnetic susceptibility measurements of the sediments correlate well with the observed changes in lithology. PIXE sample preparation procedures and calibration techniques to obtain absolute concentrations of heavy elements in the core samples are discussed. An empirical correlation between susceptibility measurements and concentration of the magnetic materials in the core obtained from PIXE will be presented. The results are promising in augmenting traditional paleomagnetic studies to develop a quantitative relationship between the measured magnetization and the concentration of magnetic materials needed for relative paleointensity studies. The PIXE analysis shows also potential in deciphering paleoenvironmental and paleoclimatic conditions during the deposition of the sedimentary section.

Karbalaei Saleh, F.; Martin, J.; Sidorovskaia, N.; Richter, C.; Hollerman, W. A.

2013-12-01

293

Major Mid-Miocene Climate Change In The Transantarctic Mountains  

NASA Astrophysics Data System (ADS)

Independent lines of evidence from paleoecology, glacial geology and marine isotopes indicate major climate change in the Dry Valley sector of the Transantarctic Mountains (TAM) at c.14 Ma. A fossil assemblage of pollen and spores, freshwater diatoms, ostracods, mosses, and insect remains has been recovered from lacustrine sediments preserved in a small morainic lake basin in the western Olympus Range. The diatom assemblage indicates that the lake existed for >103yr and was ice-free during summers. Based on the moss and insect fossils the minimum mean summer temperature (MST- Dec-Feb) was 2°C but could have been as high as 5°C. Today at the site the MST is c. -15°C. The lake-marginal vegetation was a sparse tundra dominated by mosses and liverworts. Based on pollen, Nothofagus (southern beech) was part of the lowland regional vegetation and individual dwarfed shrubs may have grown on the slopes surrounding the lake basin. The age of the deposits is well-constrained by an 40Ar/39Ar age of 14.11 ± 0.11 Ma from an in situ volcanic ash within related lacustrine sediments. Based on an independent study of the glacial stratigraphy of the western Wright and McKelvey valleys, diamictites of a wet-based glacial regime had been replaced by those of cold-based regime by 13.85 ± 0.03 Ma. The drop in temperatures and the cessation of meltwater at c. 14 Ma would have caused the regional extinction of all plant and insect life with the exception of the hardiest of soil-dwelling organisms. Paleobotanical evidence indicates that Antarctica had likely been vegetated throughout the Cenozoic, with forests replaced by tundra during the early Oligocene. The mid-Miocene extinction marks the end of tundra in the interior of Antarctica and its replacement by the polar desert biota which exists today. Changes in ?18O and Mg/Ca ratios from different sectors of the Southern Ocean indicate sea surface temperature cooling and ice sheet growth between 13.8 - 14.2 Ma. The close correlation of events in these marine records with the glaciological and biological records from the Dry Valleys strongly suggests that they are part of a major hemispheric or global climatic event.

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

2007-12-01

294

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

NASA Astrophysics Data System (ADS)

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.

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

295

High-resolution record of Early to Middle Miocene climate variability from Site 1195, Marion Plateau, NE Queensland margin  

NASA Astrophysics Data System (ADS)

Constraining and quantifying eustatic variations has been a priority for stratigraphers since the publication of the first global sea level curves by the Exxon research group in the late 1970s. Quantifying the glacio-eustatic component of sea level signals has become a greater focus as more recent work has demonstrated that far-field effects like ice-sheet gravitation and isostasy imprint on the "true" eustatic signal of waxing and waning ice sheets so that coeval signals from disparate sites may show significantly different local sea level variations. To this end, the Miocene sediments on the Marion Plateau, a drowned carbonate platform on the Queensland margin of Australia, were drilled by ODP Leg 194 to provide an independent, southern hemisphere test of the sea level record of the New Jersey Margin of North America, the most complete and oft-cited record of Cenozoic sea level variability. A high-resolution record is critical to compare sea level variations across hemispheres. Natural Gamma Ray (NGR) logs of core holes can provide a complete, high-resolution record independent of any problems with core recovery or sampling interval. We here present a NGR record of ODP Site 1195 tied to recently completed nannofossil assemblage data, planktic/benthic foraminiferal ratios, sedimentary particle counts, and benthic foraminifera stable isotopes. Peaks in glauconite and clay content correspond to peaks in NGR. The largest of these peaks correspond to sequence boundaries (lowstands), as glauconite accumulates during periods of low sedimentation along this carbonate-dominated margin. These sequence boundaries, in turn, are each associated with marine oxygen isotope events ("Mi Events") and correlate to sequences on the New Jersey margin, the Gulf of Papua, Great Australian Bight, and McMurdo Sound, indicating that these sequences are eustatically controlled. Although sedimentary particle counts only show strong peaks of glauconite at sequence boundaries, the NGR record shows long-period, low-amplitude variations in NGR between 20 and 18 Ma, a time corresponding to a pre-platform muddy ramp, short-period, high-amplitude variations between 18 and 14.8 Ma, a period of higher sea levels during the Miocene Climatic Optimum (MCO) and a dramatic spike corresponding to Mi3a at 14.8 Ma during the Middle Miocene Climate Transition (MMCT) followed by a slow decrease in the amplitude and frequency of variation during subsequent Antarctic ice growth and the drowning of the Marion Plateau. The variations in the NGR profile correspond directly (at a higher resolution) to variations in the oxygen isotope record, allowing us to create a cyclostratigraphic record that reflects fluctuations in oxygen isotopes. Calcareous nannofossil populations respond to variations in surface water nutrient availability and temperature; these changes coincide with climatic events of the early Miocene, including the MCO, the MMCT and the stepwise formation of ice sheets on Antarctica (<13.6 Ma). Calcareous nannofossil data show evidence for significantly cooler surface water at the Marion Plateau coinciding with the end of the MCO.

Lowery, C.; Browning, E.; Leckie, R. M.; John, C. M.

2012-12-01

296

Evidence for Repeated Early Miocene Glaciation and the Cutting of Upper Taylor Valley from the Friis Hills, Antarctica  

NASA Astrophysics Data System (ADS)

The Friis Hills, located at the head of Taylor Valley in the the McMurdo Dry Valleys, hold a sequence of stacked tills at least Early Miocene in age. Sedimentology, clast lithology and bedrock striations indicate these tills were deposited from wet-based glaciers that flowed southeastward down a shallow paleovalley toward the Ferrar trough. Interbedded paleosols, fluvial, and glaciolacustrine deposits register ice-free periods when the valley held small streams and ponds. Exceptionally well-preserved fossil biota suggests mild conditions during at least two of these interglacial episodes. Proglacial lacustrine deposits that include dropstones and debris flows mark the return of glacial conditions but fossil leaves and wood of Nothofagus suggest conditions during the initial phase of ice advance were also relatively mild. Geomorphic relationships show that major valley incision must have taken place after deposition of these sediments as the Friis Hills is today a flat-topped inselberg, about 5 km across, isolated from nearby topography by the deep glacial troughs of the Taylor Valley drainage. A second suite of tills, directly overlying the first, registers a reorganized glacial system with ice streaming eastward, roughly parallel to Taylor Valley. Like the first, these tills were deposited during repeated ice advances but glaciers never fully inundated the Friis Hills and ice-free periods are marked by only weak weathering surfaces and thin glaciolacustrine deposits. We interpret the changing glacial pattern to reflect headward cutting in upper Taylor Valley and the capture of ice from the Ferrar drainage. A volcanic ash interbed dated by Ar-Ar at 19.76 (±0.11) Ma occurs in a Taylor Valley-oriented drift near the eastern edge of the Friis Hills plateau. Based on its stratigraphic position, the older suite of tills and fossil-bearing interbeds are >19.76 Ma. Underlying bedrock striations show that ice flow had been redirected into Taylor Valley by this time. The preservation of the ash adjacent to Taylor Glacier suggests that cutting had already deepened the Taylor trough enough to protect the deposit from erosion during later glacier advances. The Friis Hills deposits are the first to show terrestrial evidence for Early Miocene-aged (or older) glacier cycles and the biota will provide novel constraints on paleoclimate. These tills may also help shed light on how Sirius Group deposits relate to the well-dated Middle Miocene-aged glacial record from the western Dry Valleys. Sirius Group tills occur on Table Mountain only 20 km to the south of the Friis Hills and at the same elevation. The lithology of these sediments is similar to that of the older tills in the Friis Hills and like them these sediments show ice flow into the Ferrar trough. One major difference is the degree of lithification. Tills in the Friis Hills are only weakly consolidated, whereas Sirius Group deposits are strongly lithified. This suggests that the Sirius Group in the southwestern Dry Valleys may be older than 19.76 Ma and could date to a period not long before deposition began on the Friis Hills. This research is supported by NSF OPP 0739693.

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

2009-12-01

297

Petrified wood from the Miocene volcanic sequence of Coromandel Peninsula, northern New Zealand  

Microsoft Academic Search

Petrified (silicified) wood is found throughout the Miocene sub?aerial volcanic sequence of Coromandel Peninsula. The identification of 160 samples, mostly collected from geological formations of known age, shows that over the period from 18–6 Ma the majority of trees within local forests were angiosperms, particularly southern beech (Nothofagus spp.) and casuanna (Casuarinaceae). A species close to modern Weinmanma and Lauretta

P. R. Moore; R. Wallace

2000-01-01

298

Late Miocene Teeth from Middle Awash, Ethiopia, and Early Hominid Dental Evolution  

Microsoft Academic Search

Late Miocene fossil hominid teeth recovered from Ethiopia's Middle Awash are assigned to Ardipithecus kadabba. Their primitive morphology and wear pattern demonstrate that A. kadabba is distinct from Ardipithecus ramidus. These fossils suggest that the last common ancestor of apes and humans had a functionally honing canine-third premolar complex. Comparison with teeth of Sahelanthropus and Orrorin, the two other named

Yohannes Haile-Selassie; Gen Suwa; Tim D. White

2004-01-01

299

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

Microsoft Academic Search

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.

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

1981-01-01

300

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

E-print Network

C4 expansion in the central Inner Mongolia during the latest Miocene and early Pliocene Chunfu Zhang a, , Yang Wang a , Tao Deng b , Xiaoming Wang c , Dana Biasatti a , Yingfeng Xu a , Qiang Li b of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, 100044, PR China c

Wang, Yang

301

Sedimentary facies, mineralogy, and geochemistry of the sulphate-bearing Miocene Dam Formation in Qatar  

Microsoft Academic Search

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

H. G. Dill; R. Botz; Z. Berner; D. Stüben; S. Nasir; H. Al-Saad

2005-01-01

302

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

Microsoft Academic Search

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

Alfred J. Mead

1999-01-01

303

Middle Miocene to present plate tectonic history of the southern Central American Volcanic Arc  

Microsoft Academic Search

New mid Miocene to present plate tectonic reconstructions of the southern Central American Volcanic Arc (CAVA) reveal that the inception of Cocos Ridge subduction began no earlier than 3 Ma, and possibly as late as 2 Ma. The Cocos Ridge has been displaced from the Malpelo Ridge to the southeast since ?9 Ma along the Panama Fracture Zone (PFZ) system.

Ian MacMillan; Phillip B. Gans; Guillermo Alvarado

2004-01-01

304

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

E-print Network

sirenian rib fragments discovered between 2007 and 2009 by Aldo Rincon and others. 2. Stratigraphic setting m thick succession of volcani- clastic marine sediments (Fig. 2). (Note that all ages in Ma overlies Late Miocene (w11.5 Ma) volcanic arc columnar basalts (Fig. 2). The Tobabe Formation

Bermingham, Eldredge

305

New material of Carnivora (Mammalia) from the Late Miocene of Axios Valley, Macedonia, Greece  

Microsoft Academic Search

A new collection of carnivores from the late Miocene deposits of Axios Valley, Macedonia, Greece was collected in 2004–2009 at the localities named Xirochori 1 (XIR) and Ravin de la Pluie (RPl), dated to the late Vallesian (MN 10), as well as in Ravin des Zouaves 5 (RZO), dated to the early Turolian (MN 11). The studied material is described

George D. Koufos

306

Miocene Glacioeustasy and Carbonate Sequences on the Marion Plateau, Northeastern Australia: Inferences from Distal Slope Records  

Microsoft Academic Search

Understanding the timing and magnitude of eustatic changes (global sea-level) is key to improving sequence stratigraphic and sedimentologic models, with wide implications for environmental changes and future exploration of fossil fuels. In the Oligo-Miocene, the magnitude of eustatic changes also provides a clue on Antarctic ice volume. The current best eustatic curve is largely based on records from the New

C. M. John; E. Browning; M. Leckie; G. Karner

2008-01-01

307

Paleogeographic evolution of the Late Miocene Lake Pannon in Central Europe  

Microsoft Academic Search

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:

Imre Magyar; Dana H Geary; Pál Müller

1999-01-01

308

Late Miocene to Pliocene palaeogeography of the Paratethys and its relation to the Mediterranean  

Microsoft Academic Search

The palaeogeographic evolution of the Paratethyan and Mediterranean realms are reconstructed with three maps ranging from the Late Miocene to the Middle–Late Pliocene. The maps are based on the facial analysis of selected deposits, clastic input, slope-slide process analyses as well as biogeographic data of the planktic, benthic and terrestrial biota. Characteristic fossil assemblages are used for palaeobathymetric and palaeohydrologic

Sergej V. Popov; Irina G. Shcherba; Lubov B. Ilyina; Lidija A. Nevesskaya; Nina P. Paramonova; Sergej O. Khondkarian; Imre Magyar

2006-01-01

309

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

NASA Astrophysics Data System (ADS)

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.

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

310

Early Miocene cricetids (Rodentia) from the Junggar basin (Xinjiang, China) and their biochronological implications  

Microsoft Academic Search

Among the 14small mammal species from the early Miocene locality of the northern area of the Junggar basin (northern Xinjiang, China), four species are cricetids (Rodentia): unnamed species of Cricetodon and Eumyarion, and two new species, Karydomys debruijni nov. sp. and Megacricetodon beijiangensis nov. sp. Some aspects of the morphology of Cricetodon sp. are shared by Eucricetodon from the late

Olivier Maridet; Wen-Yu Wu; Jie Ye; Shun-Dong Bi; Xi-Jun Ni; Jin Meng

311

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

E-print Network

Mid-Miocene cooling and the extinction of tundra in continental Antarctica Adam R. Lewisa well preserved fossils of lacustrine and terrestrial organisms from the McMurdo Dry Valleys sector of a tundra community that inhabited the mountains before stepped cooling that first brought a full polar

Marchant, David R.

312

Early Miocene pollen and spores from western Jylland, Denmark environmental and climatic implications  

E-print Network

: A palynological analysis of a Lower Miocene cored section from Sønder Vium in western Jylland, Denmark, provides of the palynological assemblages including widely distributed Taxodium swamps, suggests a warm, frost-free temperate led to the buildup of theAntarctic polar cap (e.g., Lear et al. 2003; Roberts et al. 2003). In central

Vajda, Vivi

313

Iron oxide mineralogy in late Miocene red beds from La Gloria, Spain: rock-magnetic,  

E-print Network

Iron oxide mineralogy in late Miocene red beds from La Gloria, Spain: rock-magnetic, voltammetric techniques that are designed for the analysis of magnetic iron oxides are very sensitive. The same applies by rock-magnetic techniques (IRM component analysis) and by two less traditional methods: visible

Utrecht, Universiteit

314

Miocene sharks in the Kendeace and Grand Bay formations of Carriacou, The Grenadines, Lesser Antilles  

Microsoft Academic Search

The Miocene chondrichthyan fauna from the Kendeace and Grand Bay formations consists of five species which have been identified from the remains of teeth. These are Carcharias taurus (sand-tiger shark), Isurus oxyrinchus (shortfin mako shark), Carcharocles megalodon (mega-tooth shark), Carcharhinus obscurus (requiem shark) and Hemipristis serra (extinct snaggletooth shark). No further skeletal fish remains, Chondrichthyes or Actinopterygii, were discovered. Teeth

ROGER W. PORTELL; G ORDON HUBBELL; S TEPHEN K. DONOVAN; J EREMY L. GREEN; DAVID A. T. HARPER; RON PICKERILL

315

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

Microsoft Academic Search

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

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

2004-01-01

316

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

NASA Astrophysics Data System (ADS)

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.

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

317

The Biomarker Properties and Comparisons of ?ahinali, Beypazari and Karapinar (Turkey) Coaly Plio-Miocene Depositions  

NASA Astrophysics Data System (ADS)

The distribution values of m/z 191 triterpane and m/z 217 sterane of coaly Plio-Miocene units determined by GC-MS were used to compare biomarker properties of ?ahinali, Beypazar? and Karap?nar areas located in Ayd?n, Ankara and Konya (Turkey) regions within this study. In the ?ahinali (Ayd?n) region the Miocene units consist of conglomerate, coal, clayey coal, sandstone, siltstone, claystone, clayey limestone and silicified limestone. Middle-Upper Miocene units of the Beypazar? (Ankara) Basin are represented by conglomerate, agglomerate, sandstone, siltstone, claystone, coal, bituminous shale, limestone, and tuff. The Pliocene Karap?nar (Konya) area of interest, which is characterized by sandstone, siltstone, claystone, mudstone, lake and river bed coal deposits. When all the biomarker values are considered, it can be concluded that the organic matter is not mature. In two areas - except ?ahinali - gammacerane is present indicating salinity. According to the C27, C28 ve C29 sterane distribution, it can be observed that the dominant organic matter is terrestrial based and accompanied by simple herbaceous and alg. The deposition conditions are seen to be anoxic even though some oxic depositions are found in areas. All the areas had oleananes indicating angiosperm presence. C29/C30 hophane ratio and decrease in C31-C35 peak height indicated detrial facies in all the areas. Key Words: Plio-Miocene, Coal, Biomarker, Turkey

Unal, Neslihan; Hokerek, Selin; Altunsoy, Mehmet; Ozcelik, Orhan; Yalcin Erik, Nazan

2014-05-01

318

The earliest modern mongoose (Carnivora, Herpestidae) from Africa (late Miocene of Chad)  

Microsoft Academic Search

We report on the earliest modern mongooses of Africa, from the late Miocene (ca. 7 Ma) of the hominid locality TM 266, Toros-Menalla, Chad. The material is based on fragmentary dentitions of three individuals. The main diagnostic feature of the Chadian species is the great development of the shear in the carnassials, which distinguishes the Chadian specimens from all extant herpestids

Stéphane Peigné; Louis de Bonis; Andossa Likius; Hassane Taïsso Mackaye; Patrick Vignaud; Michel Brunet

2005-01-01

319

Abundance variations of benthic foraminifera in Upper Oligocene and Miocene strata of south Louisiana  

SciTech Connect

Abundance variations of benthic foraminifera in some upper Oligocene and Miocene strata of south Louisiana were studied to evaluate trends of species dominance, associations, and faunal diversity. Fifty-seven well-cutting samples were obtained from eleven wells in six parishes: Vermilion, St. Mary, St. Martin, Assumption, Terrebonne, and Lafourche. In addition, core samples were obtained from two wells in Terrebonne Parish.

Nunn, L.L.; Sen Gupta, B.K.

1986-09-01

320

Foraminiferal record of Oligocene-Miocene shales from the Limon Basin, eastern Costa Rica  

SciTech Connect

Foraminiferal analysis of an unusually thick and continuous section of Tertiary shales from the western margin of the Limon Basin, Costa Rica, indicates that rocks from this section are older than similar facies elsewhere in the basin. Approximately 620 meters of silty shales from the Quebrada Terciopelo belong to zones N3 through N9 while the oldest shales from the rest of the basin are in N12 to N13. The lowermost N3 zone is characterized by the presence of the Late Oligocene larger foraminifera Lepidocyclina waylandvaughani and Heterostegina antillea associated with oncolite clasts in a siltstone. Shales above contain typical Early to Middle Miocene planktonic foraminifera, including Catapsydrax stainforthi, Globorotalia kugleri, G. sicanus, and G. peripheroronda. The first two species, used widely as Early Miocene markers and reported to have nonoverlapping stratigraphic ranges, are found together within a short interval in this section. This Quebrada Terciopelo sedimentary section shows the transition from a shallow nearshore environment in the Late Oligocene to an open marine outer shelf or upper slope in the Miocene. The biostratigraphic analysis demonstrates than an approximately 70 meter thick Late Oligocene (N3) to Early Miocene (N5) section is repeated. This is apparently related to normal faulting associated with the uplift of the Talamanca Mountains.

Cassell, D.T.; Sen Gupta, B.K.

1985-01-01

321

A semi-aquatic Arctic mammalian carnivore from the Miocene epoch and origin of Pinnipedia  

E-print Network

LETTERS A semi-aquatic Arctic mammalian carnivore from the Miocene epoch and origin of Pinnipedia and thewalrus)are semi-aquatic, generally marine carnivores the limbs of which have been modified into flippers that includes skunks, badgers, weasels and otters). Although the position of pinnipeds within modern carnivores

Sullivan, Jack

322

Biogeographical and phylogenetic implications of an early Miocene wren (Aves: Passeriformes: Acanthisittidae) from New Zealand  

Microsoft Academic Search

A new species and genus of acanthisittid wren (Aves: Passeriformes: Acanthisittidae) is described from the Early Miocene (19–16 Ma) St Bathans Fauna from Otago, New Zealand, based on four fossil bones. The first Tertiary fossil passerine to be described from New Zealand, it is similar in size to New Zealand's smallest extant bird, the Rifleman Acanthisitta chloris. A phylogenetic analysis

Trevor H. Worthy; Suzanne J. Hand; Jacqueline M. T. Nguyen; Alan J. D. Tennyson; Jennifer P. Worthy; R. Paul Scofield; Walter E. Boles; Michael Archer

2010-01-01

323

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

E-print Network

Molar crown formation in the Late Miocene Asian hominoids, Sivapithecus parvada and Sivapithecus of the first data for molar crown development in one hominoid genus, Sivapi- thecus. The data are compared to a range of extant and extinct hominoids. Crown formation times (CFTs), daily rates of enamel secretion

Smith, Tanya M.

324

Rapid and major coastal subsidence during the late Miocene in south-central Chile  

E-print Network

, University of Saskatchewan, 114 Science Place, Sask., Canada SK S7N 5E2 f Departamento de Geologi. These facies were deposited by gravity flows, with turbidity currents and sandy debris flows as the main modes Ltd. All rights reserved. Keywords: Late Miocene; Early Pliocene; South-central Chile; Gravity flows

Finger, Kenneth L.

325

Ross Sea Region in the Middle Miocene: A Glimpse into the Past  

Microsoft Academic Search

Fossil diatoms and pollen from sea-floor sediments beneath the Ross Ice Shelf indicate that a permanent ice cover was not present in the Ross Sea and that vegetation including angiosperms, gymnosperms, and ferns existed on at least some parts of the largely glaciated Antarctic mainland in the late middle Miocene.

Howard Brady; Helene Martin

1979-01-01

326

Regional stratigraphic scheme and paleogeographic events of the late Miocene, Pliocene and Quaternary in Armenia  

Microsoft Academic Search

Regional Upper Cenozoic stratigraphic schemes are available from several summarizing works [2?5, 7?10]. In the present communication, these materials are discussed with consideration of new data on upper Miocene, Pliocene, and Quaternary stratigraphy and paleogeography of Armenia, which make it possible to significantly refine the scheme for Armenia. The scheme is largely based on reference sections of the large Sevan,

Yu. V. Sayadyan

2006-01-01

327

Middle Miocene vertebrates from the Amazonian Madre de Dios Subandean Zone, Perú  

NASA Astrophysics Data System (ADS)

A new middle Miocene vertebrate fauna from Peruvian Amazonia is described. It yields the marsupials Sipalocyon sp. (Hathliacynidae) and Marmosa (Micoureus) cf. laventica (Didelphidae), as well as an unidentified glyptodontine xenarthran and the rodents Guiomys sp. (Caviidae), “Scleromys” sp., cf. quadrangulatus-schurmanni-colombianus (Dinomyidae), an unidentified acaremyid, and cf. Microsteiromys sp. (Erethizontidae). Apatite Fission Track provides a detrital age (17.1 ± 2.4 Ma) for the locality, slightly older than its inferred biochronological age (Colloncuran-early Laventan South American Land Mammal Ages: ˜15.6-13.0 Ma). Put together, both the mammalian assemblage and lithology of the fossil-bearing level point to a mixture of tropical rainforest environment and more open habitats under a monsoonal-like tropical climate. The fully fluvial origin of the concerned sedimentary sequence suggests that the Amazonian Madre de Dios Subandean Zone was not part of the Pebas mega-wetland System by middle Miocene times. This new assemblage seems to reveal a previously undocumented “spatiotemporal transition” between the late early Miocene assemblages from high latitudes (Patagonia and Southern Chile) and the late middle Miocene faunas of low latitudes (Colombia, Perú, Venezuela, and ?Brazil).

Antoine, Pierre-Olivier; Roddaz, Martin; Brichau, Stéphanie; Tejada-Lara, Julia; Salas-Gismondi, Rodolfo; Altamirano, Ali; Louterbach, Mélanie; Lambs, Luc; Otto, Thierry; Brusset, Stéphane

2013-03-01

328

Tsunami-induced conglomerates in Miocene upper bathyal deposits, Chita Peninsula, central Japan  

Microsoft Academic Search

The Tsubutegaura conglomeratic tsunamiites occur in the middle section of the Miocene storm-related sand-silt alternation system in the Chita Peninsula, central Japan. Deposition of the system in the upper bathyal environment in a bay and synsedimentary seismic activity has been elucidated by palaeontological, palaeogeographical and sedimentological studies. Two coupled units, each built up by a conglomerate layer with an overlying

Tsunemasa Shiki; Teiji Yamazaki

1996-01-01

329

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

Microsoft Academic Search

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

David W. Steadman

1981-01-01

330

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

E-print Network

Changes in Paratethyan marine molluscs at the Early/Middle Miocene transition: diversity, palaeo: HARZHAUSER, M., MANDIC, O. & ZUSCHIN, M. 2003. Changes in Paratethyan marine molluscs at the Early for the development of mollusc faunas (gastropods and bivalves) in the Central Paratethys. Here, we first discuss

Zuschin, Martin

331

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

PubMed Central

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

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

2014-01-01

332

OligoceneMiocene middle crustal flow in southern Tibet: geochronology of Mabja Dome  

E-print Network

of middle crustal rocks in southern Tibet. Zircons from a deformed leucocratic dyke swarm yield a U­Pb age of 23.1 + 0.8 Ma, providing the first age constraint on the timing of middle crustal ductile horizontal and subhorizontal stretching had ceased by the middle Miocene. Mica 40 Ar/39 Ar ages from schists and orthogneisses

Lee, Jeff

333

Tectono-stratigraphic evolution of the continental Miocene basins in southern Anatolia  

NASA Astrophysics Data System (ADS)

The exposed portion of the Tauride fold-thrust belt in southern Turkey is flanked and overlain by Neogene sedimentary basins. To the south and on top of the high ranges, these basins are mainly marine, whereas previously poorly studied intra-montane basins dominated by continental deposits are exposed to the north. We have studied the stratigraphy and structure of these continental basins - the Alt?napa, Yalvaç and Ilg?n Basins. Their stratigraphy displays overall fining upward sequences of fluvio-lacustrine sediments, deposition of which interrupted by basin-wide unconformities; similar hiatuses seems to exist in each basin. The most prominent unconformity surface occurred during the Middle Miocene and corresponds to the timing of volcanic activity in the region. 40Ar/39Ar dating of the volcaniclastic samples from the Alt?napa and Ilg?n basins yielded 11.8-11.6 Ma ages. The main basin forming regional deformation phase was extensional and occurred during the Middle Miocene. The extension directions obtained from paleostress inversion techniques indicate multidirectional extension under vertical uniaxial stress which are compatible with the recent seismic activity and available focal mechanism solutions. The main basin-bounding faults, however, are constrained mainly N-S to NW-SE implying that they are reactivated structures. The Middle Miocene and onwards extensional history of these basins occurs behind and atop a thrust front along the Cyprus arc, extending towards the Antalya nappes and Aksu thrust in the heart of the Isparta angle. The synchrounous, curved pairs of thrust fronts associated with subduction and overriding plate extension suggests that the Cyprus subduction zone has been retreating relative to central Anatolia since, at least, the Middle Miocene time. In addition to extensional history of the region, these continental basins contain evidence for the post-Late Miocene differential uplift of the Taurides in southern Anatolia. All of these continental basins were above sea level during the Middle and Late Miocene and are now found at an elevation of 1 km. On the other hand, the upper Miocene marine deposits just south of the study area currently are at an elevation of ~2 km, and have therefore been uplifted at least 1 km more than the continental basins to the north. We conclude that the current high elevation of the Taurides is synchronous with, and at least in part related to late Neogene extension and vertical differential uplift, likely related to the dynamics of the Cyprian subduction zone.

Koç, Ayten; Kaymakci, Nuretdin; van Hinsbergen, Douwe J. J.; Kuiper, Klaudia F.; Vissers, Reinoud L. M.

2014-05-01

334

Tracking Arabia-India motion from Miocene to Present  

NASA Astrophysics Data System (ADS)

Although small, the present-day Arabia-India motion has been captured by several global and regional geodetic surveys that consistently show dextral motion of a few mm/yr, either transpressive or transtensive (Fournier et al., 2008). This motion is accommodated along the Owen Fracture Zone, an active strike-slip boundary that runs for more than 700 km from the Somalia-India-Arabia triple junction in the south to the Dalrymple trough in the north. Two recent marine cruises conducted along this fault aboard the BHO Beautemps-Beaupré (AOC 2006 and OWEN 2009) using a high resolution multibeam sounder (Simrad EM120, 10 m vertical resolution) provided a complete map of the active fault and confirmed a present-day pure dextral motion. The surface breaks closely follow a small circle of the Arabia-India motion, with several pull-part basins at the junctions between the main segments of the fault. Geomorphologic offsets reach 10 km, suggesting that the mapped fault has been active with the same style for past several million years. When did this motion start? The difficulty in tracking the past Arabia-India motion is that there is no direct kinematic indicator available, since the boundary has been strike-slip and/or convergent during the Tertiary. Motion was most probably sinistral during the rapid northward travelling of India towards Eurasia in the early Tertiary, Arabia being rigidly attached to Africa until the opening of the Gulf of Aden. However, the nature and location of the Arabia-India boundary at that time remain speculative. Throughout the Miocene, the relative motion between India and Arabia has been indirectly recorded at the Sheba and Carslberg ridges, the former recording Arabia-Somalia motion (opening of the Gulf of Aden) and the latter India-Somalia motion (Indian Ocean opening). Both ridges have been studied with some details recently, using up to date magnetic lineations identification (Merkouriev and DeMets, 2006; Fournier et al., 2009). We combine these studies to derive Arabia/India kinematics for the past 20 Myrs. As observed today, opening rates at Sheba ridge and at Carlsberg ridge remained closed since Chron 5D (17.2 Ma), thus pointing to small differential motion between Arabia and India. However, our kinematic model suggests that dextral shearing prevailed since the very beginning of opening of the Gulf of Aden. This has significant implications for the forces that drive the Arabia plate and Arabia-India coupling at their transform boundary. Fournier et al., 2008, In-situ evidence for dextral active motion at the Arabia-India plate boundary, Nature Geoscience, doi:10.1038/ngeo.2007.24. Fournier et al., 2009, Arabia-Somalia plate kinematics, evolution of the Aden-Owen-Carlsberg triple junction, and opening of the Gulf of Aden, J. Geophys. Res., in revision. Merkouriev and DeMets, 2006, Constraints on Indian plate motion since 20 Ma from dense Russian magnetic data: Implications for Indian plate dynamics, Geochem. Geophys. Geosyst., doi:10.1029/2005GC001079.

Chamot-Rooke, N. R.; Fournier, M.

2009-12-01

335

Correlation and zonation of miocene strata along the atlantic margin of North America using diatoms and silicoflagellates  

USGS Publications Warehouse

Six Atlantic Miocene siliceous microfossil zones are proposed based on onshore and offshore samples from the United States Atlantic Margin. Diatoms and silicoflagellates are used to establish the zones. These zones are from oldest to youngest: 1. Zone I Actinoptychus heliopelta Concurrent Range Zone - Early Miocene 2. Zone II Delphineis ovata Partial Range Zone - late Early to early Middle Miocene 3. Zone III Delphineis ovata/Delphineis penelliptica Concurrent Range Zone - early Middle Miocene 4. Zone IV Delphineis penelliptica Partial Range Zone - Middle Miocene 5. Zone V Delphineis penelliptica/Coscinodiscus plicatus Concurrent Range Zone - Middle Miocene 6. Zone VI Coscinodiscus plicatus Partial Range Zone - Middle Miocene. The six zones are easily traced along the Southern and Middle Atlantic Seaboard, but the older three are found for the most part between Cape Hatteras and New Jersey. There is some suggestion of sea-level change during Zone IV. Using rare planktonic diatoms that are index species from other regions and the zonal markers established in this study, correlation can be made with the Standard Foraminiferal Zones, the North Pacific Diatom Zones and with DSDP core 391A in the Blake-Bahama Basin. ?? 1978.

Abbott, W.H.

1978-01-01

336

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

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.

Hudson, Mark R.; John, David A.; Conrad, James E.; McKee, Edwin H.

2000-01-01

337

Whiting-related sediment export along the Middle Miocene carbonate ramp of Great Bahama Bank  

NASA Astrophysics Data System (ADS)

Modern aragonite needles are present all along the modern leeward margin of Great Bahama Bank (ODP Leg 166), while Middle Miocene sediments contain needles only in more distal areas (Sites 1006 and 1007). In contrast to the rimmed, flat-topped platform topography during the Plio-Pleistocene, the Miocene Great Bahama Bank morphology is a carbonate ramp profile. This might imply a different location and precipitation type for Miocene aragonite needles. In this study, aragonite needles in Miocene sediments were isolated using a granulometric separation method. Furthermore, the isolation of the various carbonate components enables the identification of primary versus diagenetic components. The Miocene aragonite needles are concentrated in the finest granulometric sediment fractions (<12 ?m). The fraction-specific geochemical analyses (?13C, ?18O and Sr elemental abundance) represent useful tools to assess the possible sources of the aragonite mud. The geochemical variation of the fractions, rich in pristine aragonite needles, and the characteristics of the needle morphology point to whiting phenomena as the main sediment source and algal fragmentation as a minor component. Both components indicate shallow-water environments as the main sediment source area. Ramp-top-related fine-grained particles now present at distal sites were likely exported as suspended material similar to present-day transport mechanisms. The scarcity of needles at proximal sites is probably linked to hydrodynamic processes but dissolution and recrystallization processes cannot be excluded. The granulometric separation approach applied here enables a better characterization of the finest carbonate particles representing an important step towards the discrimination between primary and diagenetic fine-grained components.

Turpin, Mélanie; Emmanuel, Laurent; Reijmer, John J. G.; Renard, Maurice

2011-11-01

338

Seawater osmium isotope evidence for a middle Miocene flood basalt event in ferromanganese crust records  

USGS Publications Warehouse

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.

Klemm, V.; Frank, M.; Levasseur, S.; Halliday, A.N.; Hein, J.R.

2008-01-01

339

?18O and Marion Plateau backstripping: Combining two approaches to constrain late middle Miocene eustatic amplitude  

NASA Astrophysics Data System (ADS)

?18Obenthic values from Leg 194 Ocean Drilling Program Sites 1192 and 1195 (drilled on the Marion Plateau) were combined with deep-sea values to reconstruct the magnitude range of the late middle Miocene sea-level fall (13.6 11.4 Ma). In parallel, an estimate for the late middle Miocene sea-level fall was calculated from the stratigraphic relationship identified during Leg 194 and the structural relief of carbonate platforms that form the Marion Plateau. Corrections for thermal subsidence induced by Late Cretaceous rifting, flexural sediment loading, and sediment compaction were taken into account. The response of the lithosphere to sediment loading was considered for a range of effective elastic thicknesses (10 < Te < 40 km). By overlapping the sea-level range of both the deep-sea isotopes and the results from the backstripping analysis, we demonstrate that the amplitude of the late middle Miocene sea-level fall was 45 68 m (56.5 ± 11.5 m). Including an estimate for sea-level variation using the ?18Obenthic results from the subtropical Marion Plateau, the range of sea-level fall is tightly constrained between 45 and 55 m (50.0 ± 5.0 m). This result is the first precise quantitative estimate for the amplitude of the late middle Miocene eustatic fall that sidesteps the errors inherent in using benthic foraminifera assemblages to predict paleo water depth. The estimate also includes an error analysis for the flexural response of the lithosphere to both water and sediment loads. Our result implies that the extent of ice buildup in the Miocene was larger than previously estimated, and conversely that the amount of cooling associated with this event was less important.

John, Cédric M.; Karner, Garry D.; Mutti, Maria

2004-09-01

340

Paleogeographic and structural setting of Miocene strata in central western Nevada  

SciTech Connect

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.

Stewart, J.H. (Geological Survey, Menlo Park, CA (United States))

1993-04-01

341

The giant bite of a new raptorial sperm whale from the Miocene epoch of Peru.  

PubMed

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

Lambert, Olivier; Bianucci, Giovanni; Post, Klaas; de Muizon, Christian; Salas-Gismondi, Rodolfo; Urbina, Mario; Reumer, Jelle

2010-07-01

342

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

NASA Astrophysics Data System (ADS)

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.

Nicolaides, Stelios

1995-02-01

343

Absolute magnitude of the second-order middle to late Miocene sea-level fall, Marion Plateau, northeast Australia  

SciTech Connect

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.

Pigram, C.J.; Davies, P.J.; Feary, D.A.; Symonds, P.A. (Bureau of Mineral Resources, Canberra (Australia))

1992-09-01

344

The antiquity of riverine adaptations in Iniidae (Cetacea, Odontoceti) documented by a humerus from the late Miocene of the Ituzaingó Formation, Argentina.  

PubMed

"River dolphins" are a paraphyletic group of toothed whales (Odontoceti) that represent independent secondary invasions of freshwater habitats. Different "river dolphin" lineages display suites of convergent morphological specializations that commonly reflect adaptations to riverine and freshwater environments, such as longirostry, reduced orbits, and wide, paddle-like flippers. One lineage, the Iniidae, is presently endemic to South America, and includes several extinct Neogene taxa along with their sole extant genus, Inia (the Amazon River dolphin). We report here a humerus recovered from the late Miocene deposits of the Ituzaingó Formation in the Paraná Basin of Argentina. The specimen exhibits diagnostic features of the family Iniidae, including a scapular-sternal joint of the humerus, which is a unique anatomical connection among mammals. This joint permits enhanced parasagittal adduction of the flipper as a control surface, relative to other odontocetes, providing Inia with a high degree of maneuverability in its structurally complex and heterogenous riverine habitat. This unique anatomical connection, here documented from the late Miocene (?9 million years-6.5 million years old), not only provides the oldest diagnostic record for Iniidae, but it also indicates a similar habitat use for this lineage, a finding coincident with the current paleoenvironmental interpretation for the Ituzaingó Formation. PMID:24585575

Gutstein, Carolina Simon; Cozzuol, Mario Alberto; Pyenson, Nicholas D

2014-06-01

345

The occurrence of an abdominal fauna in an articulated tapir (Tapirus polkensis) from the Late Miocene Gray Fossil Site, Northeastern Tennessee.  

PubMed

The analysis of samples recovered from the abdominal area of an articulated tapir (Tapirus polkensis) from the Late Miocene (4.5-7 million BP) Gray Fossil Site (GFS) revealed a rich palyno-fauna comprised of about 94% egg/oocyst-like structures and 6% pollen and other palynomorphs. In addition, a group of 6 hickory nuts (Carya) was recovered from the same area suggesting that the samples represent the abdominal contents. The analysis of a sample from immediately outside the tapir produced a sample with 98% pollen and less than 0.5% egg/oocyst-like structures. The size, shape, and general morphology of egg/oocyst-like structures were analyzed with light and scanning electron microscopy and were compared to a variety of intestinal parasites found in extant ungulates, and the Perissodactyla in particular. We also compared fossil structures to the numbers and kind of intestinal parasites recovered from fecal samples from the Baird's tapir (T. bairdii) in Costa Rica and from samples collected from the lowland tapir (T. terrestris) from Ecuador to assess their similarity to our fossil sample. Based on these data, we discuss what role parasites may have played in the biology of T. polkensis during the Late Miocene-Early Pliocene. PMID:23586562

McConnell, Shannon M; Zavada, Michael S

2013-03-01

346

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

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.

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

347

Interim report on the ground-water resources of Manatee County, Florida  

USGS Publications Warehouse

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.

Peek, Harry M.; Anders, Robert B.

1955-01-01

348

Late Oligocene-Miocene transgressions along the equatorial and eastern margins of Brazil  

NASA Astrophysics Data System (ADS)

The seaboard of Brazil is a highly favorable setting for studying episodes of worldwide sea-level rise because of its passive nature. Previous studies of the equatorial coast of Brazil have led to the recognition of extensive Oligo-Miocene and Miocene marine-influenced deposits, but these deposits have been overlooked in other coastal areas of Brazil. The aim of the present study is to show the origin and evolution of late Oligocene and Miocene marine-influenced strata exposed in more than 5000 km of coastal areas along the WNW-trending equatorial and NNE-trending eastern Brazilian continental margins. We review the most relevant data concerning the strata of these ages exposed along the equatorial and eastern margins of Brazil, and combine them with new data. Based on these occurrences, we analyze the history of sea-level fluctuations and show that marine-influenced strata are more widespread in these margins than originally thought. Our main results indicate that a marine influence is not only imprinted in the deposits exposed along the equatorial margin, but it is also widespread in several areas of the eastern margin. For a long geological time interval ranging from the end of the Cretaceous or Paleogene up to the late Oligocene, most of the Brazilian coast remained a non-depositional site exposed to subaerial erosion and lateritic soil development. The combination of sea-level rise and tectonic subsidence promoted sediment accumulation in the onshore portion of several basins. Two transgressive episodes occurred: one in the Oligo-Miocene and another in the early/middle Miocene. The latter gave rise to deposition of the Barreiras Formation. However, during the supposedly middle Miocene eustatic sea-level highstand in coastal Brazil, there was a renewed and extensive phase of non-deposition and subaerial erosion with lateritic soil formation, a process that lasted up to the Late Quaternary. This mismatching of the sedimentary record with other South American and continental areas is discussed herein. As in many other areas of South America and of the world, the regressive-transgressive events recorded along the Brazilian coast most likely responded to a combination of eustatic sea-level fluctuations and local factors such as tectonic activity, intraplate stresses and changes in dynamic topography during the post-rift history of the eastern South American Plate.

Rossetti, Dilce F.; Bezerra, Francisco H. R.; Dominguez, José M. L.

2013-08-01

349

The role of CO2 in modulating Miocene climate and ice volume (Invited)  

NASA Astrophysics Data System (ADS)

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

Greenop, R.; Sosdian, S. M.; Lear, C. H.; Foster, G. L.; Wilson, P.

2013-12-01

350

Sedimentology and stratigraphy of the Miocene to Pliocene Mona Reef Complex and its relation with relative sea-level fluctuations  

E-print Network

The Miocene to Pliocene Mona Reef complex was investigated to define facies distribution, identify corals, describe strata geometries, and provide insights on porosity distribution. Two units were identified on the platform separated by a Late...

Rodriguez Delgado, Alejandra Maria

2012-05-31

351

Provenance of middle to late Miocene clastic sedimentary rocks in the central to eastern Cibao basin, northern Hispaniola  

E-print Network

The provenance of middle to late Miocene clastic sediments of Cibao basin in northern Hispaniola has been assessed via integrated methods including detrital framework modes, clay mineral assemblages and ratios, the composition of individual feldspar...

Yao, Meng

1997-01-01

352

An early Miocene age for a high-temperature event in gneisses from Zabargad Island (Red Sea, Egypt): mantle diapirism?  

E-print Network

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

Demouchy, Sylvie

353

Planktonic foraminiferal biostratigraphy of the Miocene sequence in the area between Wadi El-Tayiba and Wadi Sidri, west central Sinai, Egypt  

NASA Astrophysics Data System (ADS)

The present work deals with the study of lithostratigraphy and the planktonic foraminiferal biostratigraphy of the Early-Middle Miocene sequence in six measured stratigraphical surface sections in west central Sinai. They are namely, from north to south: Wadi El-Tayiba, Gabal Sarbut El-Gamal, Wadi Nukhul, Wadi Baba, Gabal Abu Alaqa and Wadi Sidri. The Miocene sequence, exposed in the study area, is represented lithostratigraphically by four rock units, arranged from base to top as follows: the Nukhul and Rudeis Formations (Early Miocene), the Sarbut El-Gamal Formation and the Hammam Faraun Member of the Belayim Formation (Middle Miocene). The planktonic foraminiferal biostratigraphical studies led to the recognition of 51 planktonic foraminiferal species. They are illustrated with the scanning electron microscope. Five planktonic foraminiferal biozones and one large benthonic foraminiferal zone have been recognised. They are arranged from top to bottom as follows: Orbulina suturalis/Globorotalia siakensis Zone (Middle Miocene); Borelis melo Zone (larger foraminiferal zone) (Middle Miocene); Globigerinoides sicanus Zone (Early Miocene); Globigerinoides trilobus Zone (Early Miocene); Globigerinoides altiaperturus-Catapsydrax dissimifis Zone (Early Miocene); Globigerinoides primordius Zone (Early Miocene). Correlation of these biozones with others from Egypt and the world is also attempted.

Phillip, G.; Imam, M. M.; Abdel Gawad, G. I.

1997-10-01

354

Variation in silicate weathering across the Oligocene-Miocene boundary: evidence from lithium and neodymium isotopes  

NASA Astrophysics Data System (ADS)

Changes in global silicate weathering have a profound effect on the global carbon cycle and Earth's climate on multi-million year timescales. They may also be associated with short-term (<105 yrs) climatic aberrations: for example, temperature anomalies observed across the Oligocene-Miocene (O/M) boundary (~23 Ma) have been linked to changes in silicate rock exposure on Antarctica. To explore this idea further, we present trace element data along with lithium and neodymium isotope data measured in the carbonate tests of O/M-aged planktic foraminifera. These temporal records of the Li and Nd isotopic composition (?7Li and ?Nd) of seawater generated from deep-sea sediment core material (ODP Site 926, Ceara Rise) require large samples of mono-specific foraminifera (~20 mg). Therefore we first assess the geochemical utility of the large, abundant taxa, Dentoglobigerina venezuelana, for the purposes of ?7Li and ?Nd analysis. Three morphotypes of D. venezuelana are defined based on the morphology of the final chamber and aperture architecture. We find that the palaeoecology of these morphotypes based on their Mg/Ca, ?18O, and ?13C compositions is suitably similar to allow them to be grouped for the purpose of generating "sample-hungry" continental weathering records. Because the ?7Li and ?Nd of seawater are influenced by changes in continent-derived fluvial input to the oceans, records of seawater ?7Li and ?Nd have the potential to help constrain past changes in continental weathering. Li isotopes fractionate strongly during weathering processes, with ?7Li values becoming lower as weathering reactions tend towards completion. Nd sourced from ancient continental material typically possesses distinctively unradiogenic compositions (low ?Nd) relative to younger, mantle-derived sources. Finally, local vs. global signals of weathering input can be evaluated through utilisation of the differing oceanic residence times of Li (~1 Myrs) and Nd (~1 kyrs). To this end, we present a 4 Myr isotopic and trace element record for the O/M boundary, and we use these new data to better constrain the links between weathering and climate during this interval of significant climate change.

Stewart, J.; James, R. H.; Wilson, P. A.; Anand, P.; Edgar, K. M.

2011-12-01

355

Miocene climate as recorded on slope carbonates : examples from Malta (Central Mediterranean) and Northeastern Australia (Marion Plateau, ODP LEG 194)  

Microsoft Academic Search

This study investigated the slope carbonates of two Miocene carbonate systems: the Maltese Islands (in the Central Mediterranean) and the Marion Plateau (Northeastern Australia, drilled during ODP Leg 194). The aim of the study was to trace the impact of the Miocene cooling steps (events Mi1-Mi6) in these carbonate systems, especially the Mi3 event, which took place around 13.6 Ma

Cédric Michaël John

2003-01-01

356

Miocene shearing along the northern boundary of the Jalisco block and the opening of the southern Gulf of California  

Microsoft Academic Search

New geologic and structural mapping in western Mexico shows that the tectonic boundary between the Eocene early Miocene Sierra Madre Occidental volcanic province and the Cretaceous-Paleocene Jalisco block was reactivated as a transfer zone accommodating a limited amount of lateral motion in middle and late Miocene time. Transpressional folding, left-lateral strike-slip faulting, and minor thrusting occurred between 14.5 and 11.5

Luca Ferrari

1995-01-01

357

Reevaluation of the Cablac Limestone at its type area, East Timor: Revision of the Miocene stratigraphy of Timor  

Microsoft Academic Search

The Cablac Limestone, widely recorded in Timor, has its type area on Cablac Mountain where it was regarded as a Lower Miocene shallow-marine carbonate-platform succession. The Bahaman-like facies placed in the Cablac Limestone are now known to belong to the Upper Triassic–Lower Jurassic rather than the Lower Miocene. On the northern slopes of Cablac Mountain, a crush breccia, formerly regarded

David W. Haig; Eujay W. McCartain; Myra Keep; Logan Barber

2008-01-01

358

Paleodietary reconstruction of Miocene faunas from Pa?alar, Turkey using stable carbon and oxygen isotopes of fossil tooth enamel  

Microsoft Academic Search

Miocene-age (? 15 Ma) deposits at Pa?alar in northwest Turkey contain abundant and well-preserved dental remains from a variety of herbivores. We used the carbon and oxygen isotopic compositions of inorganic carbonate in enamel from these teeth to reconstruct the paleodiet and sources of body water, respectively, of Miocene mammals. The ?13C (PDB) values of carbonate in the enamel fall

Jay Quade; Thure E. Cerling; Peter Andrews; Berna Alpagut

1995-01-01

359

The Middle Miocene climate as modeled in an atmosphere-ocean-biosphere model  

NASA Astrophysics Data System (ADS)

We present the first simulations for the Middle Miocene using a fully coupled atmosphere-ocean-biosphere model. The Middle Miocene topography, which alters both large-scale ocean and atmospheric circulation, causes a global warming of 0.7 K compared to a modern control climate. Compared to temperature proxies this warming is too small. Applying higher CO2 concentrations of 480 and 720 ppm, we are able to simulate a global warming of 2.8 K and 4.9 K compared to present-day, which is in line with proxy records. Still, a flatter equator-to-pole temperature gradient, as it is suggested by marine and terrestrial proxies, cannot be realized. One reason is that atmospheric and oceanic heat transport compensate leaving the total poleward heat transport nearly unchanged. In our contribution we will show the mechanisms that are responsible for these compensating effects in the atmosphere-ocean system.

Krapp, M.; Jungclaus, J. H.

2011-12-01

360

Sensitivity of climate and Atlantic overturning circulation to uncertain ocean gateway configurations for the late Miocene  

NASA Astrophysics Data System (ADS)

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).

Bradshaw, C.; Lunt, D. J.; Flecker, R.; Martinez-Mendez, G.

2013-12-01

361

Onset of convective rainfall during gradual late Miocene rise of the central Andes.  

PubMed

A decrease in the ratio of 18O to 16O (delta18O) of sedimentary carbonate from the Bolivian Altiplano has been interpreted to indicate rapid surface uplift of the late Miocene Andean plateau (AP). Here we report on paleoclimate simulations of Andean surface uplift with an atmospheric general circulation model (GCM) that tracks oxygen isotopes in vapor. The GCM predicts changes in atmospheric circulation and rainfall that influence AP isotopic source and amount effects. On eastern AP slopes, summer convective precipitation increases by up to 6 millimeters per day (>500%) for plateau elevations that are greater than about 2000 meters. High precipitation rates enhance the isotope amount effect, leading to a decrease in precipitation delta18O at high elevations and an increase in delta18O lapse rate. Our results indicate that late Miocene delta18O depletion reflects initiation and intensification of convective rainfall. PMID:20360069

Poulsen, Christopher J; Ehlers, Todd A; Insel, Nadja

2010-04-23

362

Basal Adare volcanics, Robertson Bay, North Victoria Land, Antarctica: Late Miocene intraplate basalts of subaqueous origin  

USGS Publications Warehouse

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

Mortimer, N.; Dunlap, W.J.; Isaac, M.J.; Sutherland, R.P.; Faure, K.

2007-01-01

363

Palynology of the Heath Formation (Miocene) from the Progreso Basin, Peru  

SciTech Connect

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.

Engelhardt, D.W. (Univ. of South Carolina, Columbia (United States)); Wood, G.D. (Amoco Production Co., Houston, TX (United States))

1993-02-01

364

Sr-isotopic, paleomagnetic, and biostratigraphic calibration of horse evolution: Evidence from the Miocene of Florida  

NASA Astrophysics Data System (ADS)

During the middle Miocene an explosive adaptive radiation resulted in the advent of grazing horses with high-crowned teeth in North America. New Sr isotopic, paleomagnetic, and biostratigraphic evidence from the Miocene marine and nonmarine sequence of the Florida panhandle calibrates the base of this adaptive radiation. The transition from the primitive outgroup species "Parahippus" leonensis to the most primitive high-crowned horse, "Merychippus" gunteri occurred after about 17.7 Ma. After this event, the lowest known stratigraphic level at which diversification (i.e., presence of two or more sympatric species) of grazing merychippine horses occurs is about 16.2 Ma, or within the early part of Chron C5BR. Although this currently is the only sequence where the parahippine-merychippine transition is directly calibrated, biochronologic evidence from other important, contemporaneous localities in Texas, Nebraska, and California indicate that diversification occurred rapidly throughout North America between about 15 and 16 Ma.

MacFadden, Bruce J.; Bryant, J. Daniel; Mueller, Paul A.

1991-03-01

365

Late Miocene hominin teeth from the Gona Paleoanthropological Research Project area, Afar, Ethiopia.  

PubMed

Since 2000, significant collections of Latest Miocene hominin fossils have been recovered from Chad, Kenya, and Ethiopia. These fossils have provided a better understanding of earliest hominin biology and context. Here, we describe five hominin teeth from two periods (ca. 5.4 Million-years-ago and ca. 6.3 Ma) that were recovered from the Adu-Asa Formation in the Gona Paleoanthropological Research Project area in the Afar, Ethiopia that we assign to either Hominina, gen. et sp. indet. or Ardipithecus kadabba. These specimens are compared with extant African ape and other Latest Miocene and Early Pliocene hominin teeth. The derived morphology of the large, non-sectorial maxillary canine and mandibular third premolar links them with later hominins and they are phenetically distinguishable and thus phyletically distinct from extant apes. PMID:25795338

Simpson, Scott W; Kleinsasser, Lynnette; Quade, Jay; Levin, Naomi E; McIntosh, William C; Dunbar, Nelia; Semaw, Sileshi; Rogers, Michael J

2015-04-01

366

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

NASA Astrophysics Data System (ADS)

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.

Combellas Bigott, Ricardo Ignacio

367

Genesis of siderite in the Upper Miocene, offshore Sarawak: Constraints on pore fluid chemistry and diagenetic history  

SciTech Connect

The cored sequence of the Upper Miocene reservoir of Baram field, offshore Sarawak, consists of cyclic deltaic-related quartz-rich sandstones and mudstones interpreted to have been deposited during storm events in shallow to midshelf water depths. The sequence is intercalated with minor tidal intervals. Authigenic siderite is common in sandstones throughout the sequence. Siderite cemented zones are up to 2 m thick. The cement is found in four different sandstone types: laminated sandstone, massive sandstone, bioturbated sandstone, and in association with shell fragments. Whole-rock XRD gives estimates of 20 to 40% siderite in bioturbated sandstones and 10 to 25% for the others. Petrographic analysis reveals that diagenetic siderite occurs in four different crystal morphologies: rhombic, [open quotes]bundles,[close quotes] acicular, and cylindrical. The rhombic siderite, which commonly occurs in bioturbated sandstone, has the most adverse effect on the poroperm characteristics of the sandstones, reducing porosity to 10% and permeability to 2 md. [sigma][sup 13]C and [sigma][sup 18]O plots show groupings based on morphology. Bundled and acicular siderite show ranges of [sigma][sup 13]C[sub PDB] of [minus]15 to [minus]25 and [sigma][sup 18]O[sub PDB] of 0 to [minus]1. The late Miocene seawater [sigma][sup 18]O estimate for the region is [minus]0.8 PDB. This would give the bundles/acicular siderite a temperature of formation range of 26[degrees] to 30[degrees]C. The [sigma][sup 18]O values are compatible with precipitation at shallow burial depth from unaltered seawater; [sigma][sup 13]C values are inherited from sulfate reduction horizons. Rhombic siderite has ranges of [sigma][sup 13]C[sub PDB] of [minus]5 to [minus]15 and [sigma][sup 18]O[sub PDB] of [minus]3 to [minus]4. The range of [sigma][sup 13]C indicates that siderite diagenesis occurred within both the shallow sulfate reduction zone and at deeper levels within the zone of decarboxylation.

Abdul Hadi, A.R.; Astin, T.R. (Univ. of Reading (United Kingdom))

1994-07-01

368

Magnetostratigraphy and tectonic rotation of Middle-Late Miocene deposits from the north-central Transverse Ranges, California  

SciTech Connect

Luyendyk and others (1980) found that most of the crustal blocks in the Transverse Ranges of souther California had undergone approximately 90[degree] clockwise rotation since the early Miocene. The authors sampled three sequences of middle-late Miocene rocks in different parts of the Transverse Ranges. The Tejon Hills, south of Arvin in the southern San Joaquin Valley, are the type area of the Cerrotejonian land mammal subage' and span the early and late Clarendonian (about 12.5--10.5 Ma). They sampled 200 m of marine Santa Margarita Fm. and the overlying fluvial Chanac Fm., which appeared to span Chrons C5AN-C5N, based on correlation with the magnetostratigraphy and mammals of the Clarendonian Ricardo Group. No tectonic rotation was found, consistent with other studies which showed that the blocks north of the Garlock and San Andreas faults have not moved in the late Cenozoic. They also samples the Hemingfordian-Hemphillian (18--5 Ma) Caliente Formation in the Dry Canyon area in the Cuyama Badlands, located on a crustal block between the Big Pine and the San Andreas faults. These beds show a progressive clockwise rotation from about 40[+-]30 in the late Hemingfordian-Barstovian (18--12 Ma) to about 35[+-]43[degree] in the Clarendonian (between 10--8 Ma) to 24[+-]6 in the Hemphillian (7--5 Ma). These data are in good agreement with other studies of the Transverse Ranges. Finally, they sampled the Santa Margarita Formation in Chorro Grande Canyon in the Sespe Creek drainage, located on the block between the Pine Mountain fault and the Munson Creek fault. This sequence was entirely of reversed polarity (probably Chron C5R, based on correlation with the Santa Margarita Fm. in the Tejon Hills) and showed a counterclockwise rotation of about 97[+-]52[degree]. This does not match any previously published results, but is consistent with the counterclockwise rotation of the middle Eocene Sespe Fm. at Hartman Ranch, on the same fault block.

Wilson, E.L. (Occidental College, Los Angeles, CA (United States). Dept. of Geology)

1993-04-01

369

A simple petrogenetic model for the formation of Miocene Low-?18O rhyolites of the Yellowstone Hotspot track, USA  

NASA Astrophysics Data System (ADS)

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.

Boroughs, S.; Wolff, J. A.; Starkel, W. A.

2012-12-01

370

Geology and palaeontology of the Late Miocene Middle Awash valley, Afar rift, Ethiopia  

Microsoft Academic Search

The Middle Awash study area of Ethiopia's Afar rift has yielded abundant vertebrate fossils (~10,000), including several hominid taxa. The study area contains a long sedimentary record spanning Late Miocene (5.3-11.2Myr ago) to Holocene times. Exposed in a unique tectonic and volcanic transition zone between the main Ethiopian rift (MER) and the Afar rift, sediments along the western Afar rift

Giday WoldeGabriel; Yohannes Haile-Selassie; Paul R. Renne; William K. Hart; Stanley H. Ambrose; Berhane Asfaw; Grant Heiken; Tim White

2001-01-01

371

A Miocene termite nest from southern Argentina and its paleoclimatological implications  

USGS Publications Warehouse

A Miocene termitarium attributable to the extant termite Syntermes (Isoptera: Termitidae, Nasutitermitinae) is the first fossil termite nest reported from South America and possibly the oldest record of the Isoptera from that continent. A new ichnogenus and ichnospecies, Syntermesichnus fontanae, is proposed for this distinctive trace fossil. It differs from nests constructed by other members of the Nasutitermitinae in its architectural organization and its large size. -from Authors

Bown, T.M.; Laza, J.H.

1990-01-01

372

Coeval formation of cataclasite and pseudotachylyte in a Miocene forearc granodiorite, southern Kyushu, Japan  

Microsoft Academic Search

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

Olivier Fabbri; Aiming Lin; Hirotaka Tokushige

2000-01-01

373

Effect of Miocene basaltic volcanism in Shanwang (Shandong Province, China) on environmental changes  

Microsoft Academic Search

Miocene (16–10 Ma) basalts, together with significantly well-preserved fossils (including animal and plant fossils) in the\\u000a contemporaneously tephra-rich Maar sediments, are located in Shanwang volcanic region, Shandong Province, China. Distribution\\u000a area of the basaltic eruption products is about 240 km2. Detailed field observations indicate that most of basaltic rocks are fissure eruptive products and some are central eruptives\\u000a constrained by

ZhengFu Guo; JiaQi Liu; XiaoYu Chen

2007-01-01

374

New material of Vallesian Late Miocene hipparions (Mammalia, Perissodactyla) from the lower Axios valley, Macedonia, Greece  

Microsoft Academic Search

The hipparions from Vallesian Late Miocene localities of the Axios valley (Macedonia, Greece) are described and compared with\\u000a those from Eurasia. In addition to the previously recognized species,H. primigenium andH. macedonicum, a third species has been determined mainly in the material from the locality of “Pentalophos 1”, PNT. It has primitive features\\u000a and it is similar toH. depereti but with

George D. Koufos

2000-01-01

375

Hydrocarbon seep-carbonates of a Miocene forearc (East Coast Basin), North Island, New Zealand  

Microsoft Academic Search

An ancient hydrocarbon seep province of 14 isolated, authigenic carbonate deposits has been identified in fine-grained, deep-marine siliciclastic strata of the Miocene East Coast Basin, North Island, New Zealand. These forearc sediments have been uplifted and complexly deformed into accretionary ridges, adjacent to the still-active Hikurangi convergent margin. Older active and passive margin strata (mid-Cretaceous to Oligocene in age) underlie

Kathleen A. Campbell; David A. Francis; Mike Collins; Murray R. Gregory; Campbell S. Nelson; Jens Greinert; Paul Aharon

2008-01-01

376

Controls on the basinwide architecture of late Miocene (Messinian) evaporites on the Levant margin (Eastern Mediterranean)  

Microsoft Academic Search

Interpretation of 2D and 3D seismic data from the Levant margin (Eastern Mediterranean) has revealed the complex depositional and structural setting of the basinwide late Miocene (Messinian) evaporites. The data set covers a total area of 20,000 km2, permitting a semi-regional investigation of the thick (up to 1.8 km) evaporitic wedge. The sequential analysis of time–structure maps, isochron maps and seismic cross-sections

Claudia Bertoni; Joe A. Cartwright

2006-01-01

377

Astronomically forced teleconnection between Paratethyan and Mediterranean sediments during the Middle and Late Miocene  

Microsoft Academic Search

A high-resolution correlation between an orbital tuned Middle and early Late Miocene record of the Central Paratethys and an astronomically calibrated Mediterranean deep marine composite record is proposed. The astronomical tuning of the Sarmatian and Pannonian sedimentary record in the Vienna Basin confirms that the beginning of the Pannonian regional stage (lower Tortonian), dated in this work at 11.42 My, is

F. Lirer; M. Harzhauser; N. Pelosi; W. E. Piller; H. P. Schmid; M. Sprovieri

2009-01-01

378

A molecular stable carbon isotope study of organic matter in immature Miocene Monterey sediments, Pismo basin  

SciTech Connect

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.

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

379

Late Oligocene-early Miocene volcanism, faulting, and sedimentation in west-central California  

Microsoft Academic Search

Abundant evidence from the rock record indicates that volcanism, active faulting, and sedimentary-basin development were widespread and nearly synchronous in west-central California during the late Oligocene and early Miocene. Volcanic activity occurred about 24-22 Ma at more than 20 eruptive centers in a northwest-trending belt, extending from Point Arena to the Orocopia Mountains. Volcanism was accompanied by marine transgression, rapid

Richard G. Stanley

1988-01-01

380

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.

381

A dissolution pipe palaeokarst of mid-Pleistocene age preserved in Miocene limestones near Staszów, Poland  

Microsoft Academic Search

Many hundreds of solution pipes are exposed in quarries near Staszów, SE Poland. The pipes are contained in late Badenian (middle Miocene) carbonates of the Chmielnik Formation and are filled with sediment derived from a weathered Sanian (Elsterian) till cover. The pipes average 1m3 in volume, though the largest is of the order of 15m3. The average depth is 1.9m;

Peter Walsh; Iwona Morawiecka-Zacharz

2001-01-01

382

Miocene to Recent structural evolution of the Nevado de Toluca volcano region, Central Mexico  

NASA Astrophysics Data System (ADS)

Based on aerial photography, satellite imagery, and detailed field work, a geological and structural model of Nevado de Toluca and its surroundings is presented. The Nevado de Toluca volcano is built upon the intersection of three complex fault systems of different age, orientation, and kinematics. These systems from the older to the younger are: (a) The Taxco-Querétaro Fault System (NNW-SSE) with clear expression south of the volcano; (b) The San Antonio Fault System (NE-SW) that runs between the San Antonio and Nevado de Toluca volcanoes; and (c) The Tenango Fault System (E-W) located to the east of Nevado de Toluca volcano. Our field data, supported by previous studies, suggest that these systems have coexisted since the late Miocene. In addition, the stratigraphy, chronology, and kinematics of fault planes point to the existence of at least three main deformation events that have affected the region since the late Miocene. During the early Miocene, an extensional phase with the same deformation style as the Basin and Range tectonics of northern Mexico caused the formation of horsts and grabens south of Nevado de Toluca and allowed the intrusion of sub-vertical dikes oriented NW-SE and NNW-SSE. During the middle Miocene, a transcurrent episode generated NE-SW faults that presented two main motions: the first movement was left-lateral with a ?3 oriented NW-SE and later turned into normal through a counter-clockwise rotation of ?3 up to a N-S position. The latest deformation phase started during the late Pliocene and produced oblique extension ( ?3 oriented NE-SW) along E-W-trending faults that later changed to pure extension by shifting of ?3 to a N-S orientation. These faults appear to control the late Pleistocene to Holocene monogenetic volcanism, the flank collapses of Nevado de Toluca volcano and the seismic activity of the region.

García-Palomo, A.; Macías, J. L.; Garduño, V. H.

2000-03-01

383

Inferred relation of Miocene Bealville Fanglomerate to Edison Fault, Caliente Canyon area, Kern County, California  

SciTech Connect

The Bealville Fanglomerate is a very coarse, local, eastern torrential facies of the middle Tertiary marine sedimentary sequence of southern San Joaquin basin. This fanglomerate is exposed in lower Caliente Canyon east of Bakersfield. It is composed of unsorted boulder-size detritus of granitic rocks now exposed in the highlands on the east and south. The fanglomerate intertongues northwestward into the overlying Miocene fluvial Bena Gravel and probably partly into the underlying Oligocene-Miocene fluvial Walker Formation. In its eastern exposure, the Bealville Fanglomerate laps onto granitic basement. The Bealville Fanglomerate, as thick as 7000 ft (2200 m), dips southward into the north-dipping Edison fault. Pre-Tertiary granitic basement was elevated on the Edison fault to the south when the fault was contemporaneously active during the Miocene. Both the fanglomerate terrane north of the fault and the adjacent granitic basement terrane south of it are now eroded to low relief, so the fault is not expressed physiographically and is inactive. In contrast, the active White Wolf fault to the southeast is expressed by the northwest-facing escarpment slope of Bear Mountain. The Bealville Fanglomerate was deposited during the early and middle Miocene as coarse alluvial detritus on the western base of the rising Sierra Nevada uplift of granitic terrane. This southward-dipping fanglomerate is coarser and thicker than other formations deposited on the eastern margin of the San Joaquin basin. These conditions indicate that the fanglomerate was deposited rapidly on a southward-tilting block against a block of granitic basement being elevated on the Edison fault to the south, and it was derived from the adjacent granitic terrane to the east and from that elevated on the Edison fault to the south.

Dibblee, T.W. Jr.; Warne, A.H.

1986-04-01

384

Deposition and diagenesis of Upper Miocene arkoses, Yowlumne and Rio Viejo fields, Kern County, California  

Microsoft Academic Search

Upper Miocene arkoses of the Yowlumne and Rio Viejo fields, southern San Joaquin Valley, California, are channel-fill turbidites characterized by the dominance of incomplete massive A or AB turbidite sequences. They occur in a depth range of 11,250 to 14,300 ft (3430 to 4360 m). Quartz and feldspar constitute more than 90% of the detrital mineralogy. However, in the Yowlumne

T. T. Tieh; R. R. Berg; R. K. Popp; J. E. Brasher; J. D. Pike

1986-01-01

385

A new Late Miocene hominoid from Kenya: Samburupithecus kiptalami gen. et sp. nov.  

NASA Astrophysics Data System (ADS)

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.

Ishida, Hidemi; Pickford, Martin

1997-11-01

386

Miocene core complex development and coeval supradetachment basin evolution of Paros, Greece  

E-print Network

; Putlitz et al., 2005; Bröcker and Keasling, 2006) and greenschist to amphibolite facies extensional overprinting in the Miocene (e.g., Brichau et al., 2006; Ring et al., 2010). The CBU is locally overlain by compositionally variable HP schists and HT... sequences of varying composition and is localized in a basin in northeast Paros (Figure 2). The stratigraphically lowest unit is a folded, incomplete marine sequence of uncertain provenance and tectonic origin. The marine units are overlain...

Bargnesi, Evan Anthony

2011-05-23

387

A contribution to the reconstruction of Miocene seepage from authigenic carbonates of the northern Apennines (Italy)  

Microsoft Academic Search

Authigenic carbonates from outcrops of the northern Apennines consist of small and irregular lenses and exhibit numerous features\\u000a indicative of cold-seep settings. Detailed petrographic, mineralogical and geochemical studies from two Miocene deposits are\\u000a presented. The first carbonate outcrop, named Fosso Riconi, is located in the foredeep basin of the Apenninic chain, whereas\\u000a the second deposit represents a satellite basin called

Stefano Conti; Daniela Fontana; Silvia Mecozzi

2010-01-01

388

Volcanic ash in the Makara Basin (Upper Miocene), Hawke's Bay, New Zealand  

Microsoft Academic Search

Volcanic ash products of intermediate composition were found, mixed with detrital sediment, in some samples of the Silver Range Sandstone. The Silver Range Sandstone is a prominent thick-bedded sandstone within the Upper Miocene thinner-bedded, flysch-like deposits in the Makara Basin, Central Hawke's Bay. The ash is probably derived from intermediate volcanism in the north-western part of the North Island. Tuff

G. J. van der Lingen

1968-01-01

389

Vegetation and climate in the latest Oligocene–earliest Miocene in Jylland, Denmark  

Microsoft Academic Search

Two exposures in Jylland, Denmark, encompassing beds of latest Oligocene to earliest Miocene age (latest Chattian–early Aquitanian) yielded well-preserved palynofloras. The assemblages indicate that Jylland was covered by extensive Taxodiaceae swamp forests in the mid-Cenozoic. Besides a Taxodiaceae–Cupressaceae association, which was overwhelmingly dominant, other common plants in this habitat were Alnus, Nyssa, Betula, Salix, Cyrilla and Myrica. Most of the

Linda M. Larsson; Vivi Vajda; Karen Dybkjær

2010-01-01

390

Taking the Temperature of Supervolcanoes: Thermal Evolution of the Miocene Yellowstone Hotspot  

Microsoft Academic Search

The rhyolitic tuffs and lavas of the Miocene Bruneau-Jarbidge eruptive center of the Yellowstone hotspot are characterized by high eruptive temperatures (900-1000°C), large eruptive volumes (100-1000 km3) and a frequency of major eruptions ~3 times greater than that of the Quaternary Yellowstone Plateau. Many of the ten units of the Cougar Point Tuff (12.7-10.5 Ma) are compositionally heterogeneous, displaying multiple

B. P. Nash; H. Cathey

2006-01-01

391

Confirmation of a late Oligocene-early Miocene age of the Deseadan Salla Beds of Bolivia.  

USGS Publications Warehouse

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

Naeser, C.W.; McKee, E.H.; Johnson, N.M.; Macfadden, B.J.

1987-01-01

392

A new Middle Miocene Niveria Jousseaume, 1884 (Mollusca: Gastropoda: Trivioidea) from Hungary  

NASA Astrophysics Data System (ADS)

A new species of Niveria from the Middle Miocene (Badenian) of the Paratethys of Borsodbóta, Hungary is described. This species is characterized by its callused dorsum and dorsal depression. Niveria jozefgregoi sp. nov. is discussed with comparative species from the Badenian of Hungary, the Pliocene of the Mediterranean region, Florida and Recent species from Madeira and the Islas Galápagos.

Fehse, Dirk

2011-02-01

393

A new chronology for the middle to late Miocene continental record in Spain  

Microsoft Academic Search

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

W. Krijgsman; M. Garcés; C. G. Langereis; R. Daams; J. van Dam; A. J. van der Meulen; J. Agustí; L. Cabrera

1996-01-01

394

Termination of the Arabian shelf sea: stacked cyclic sedimentary patterns and timing (Oligocene/Miocene, Oman)  

NASA Astrophysics Data System (ADS)

The collision of Africa and Eurasia during the Oligo-Miocene and the resultant closure of the marine passage between the eastern and western Tethys (Terminal Tethyan Event) had far-reaching consequences for the distribution of shallow water areas and the course of ocean currents. It was therefore one of the major events for the distribution and evolution of terrestrial, as well as marine faunas during the Cenozoic. The exact timing of the Terminal Tethyan Event is thus crucial for palaeobiogeographic questions. In this context, the emersion of the Arabian Shelf during the Early Miocene was an important step because of a drastic reduction of shallow-water areas. The collapse of the Arabian Shelf was initiated by the opening of the Gulf of Aden during the Oligocene. In the Janahbah region of southeastern Oman, Oligocene/Miocene limestones of the Shuwayr, Warak and Ghubbarrah formations are widely exposed. They were deposited on an extensive shallow carbonate platform that was part of the Arabian Shelf and located on the Gulf of Aden's northeastern rift shoulder. The uppermost part of the studied sedimentary succession developed immediately before the permanently subaerial exposure of the carbonate platform during the Early Miocene. Cyclic changes of intertidal and subtidal facies document a fluctuating relative sea level at different frequencies and a continuous decline of accommodation space. Single erosive surfaces with palaeokarst cavities and caliche crusts separate larger depositional cycles. These disconformities imply relatively long episodes of subaerial exposure and are interpreted to have been formed during lowstands of third-order sea-level cycles that denuded the platform. Taxonomic studies of the accompanying mollusc faunas and certain benthic foraminifers allow a correlation of the recognised subaerial disconformities with the Ru4/Ch1 to Ch4/Aq1 sequence boundaries of Hardenbol et al. (1998). This demonstrates that the termination of the Arabian shelf sea must be back-dated from the middle Burdigalian to the early Aquitanian.

Piller, W. E.; Reuter, M.; Harzhauser, M.; Kroh, A.

2009-04-01

395

DNA Sequences from a Fossil Termite in Oligo-Miocene Amber and Their Phylogenetic Implications  

Microsoft Academic Search

DNA was extracted from the fossil termite Mastotermes electrodominicus preserved in Oligo-Miocene amber (25 million to 30 million years old). Fragments of mitochondrial [16S ribosomal DNA (rDNA)] and nuclear (18S rDNA) genes were amplified by polymerase chain reaction. Phylogenetic analysis of fossil and extant 18S rDNA confirmed morphological cladistic analyses of living dictyopterans (termites, cockroaches, and mantids). The fossil termite

Rob Desalle; John Gatesy; Ward Wheeler; David Grimaldi

1992-01-01

396

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

E-print Network

. In an initial age model, we use the newly derived age of the Oligocene/Miocene (O/M) boundary of 23.0 Ma and Kent [J. Geophys. Res. 100 (1995) 6093] interpolation using the new age of the O/M boundary (23.0 Ma (lithological) cycles in high-quality deep-sea cores from Ceara Rise, western equatorial Atlantic, to orbital

Zachos, James

397

Early evidence for complex social structure in Proboscidea from a late Miocene trackway site in the United Arab Emirates  

PubMed Central

Many living vertebrates exhibit complex social structures, evidence for the antiquity of which is limited to rare and exceptional fossil finds. Living elephants possess a characteristic social structure that is sex-segregated and multi-tiered, centred around a matriarchal family and solitary or loosely associated groups of adult males. Although the fossil record of Proboscidea is extensive, the origin and evolution of social structure in this clade is virtually unknown. Here, we present imagery and analyses of an extensive late Miocene fossil trackway site from the United Arab Emirates. The site of Mleisa 1 preserves exceptionally long trackways of a herd of at least 13 individuals of varying size transected by that of a single large individual, indicating the presence of both herding and solitary social modes. Trackway stride lengths and resulting body mass estimates indicate that the solitary individual was also the largest and therefore most likely a male. Sexual determination for the herd is equivocal, but the body size profile and number of individuals are commensurate with those of a modern elephant family unit. The Mleisa 1 trackways provide direct evidence for the antiquity of characteristic and complex social structure in Proboscidea. PMID:22357934

Bibi, Faysal; Kraatz, Brian; Craig, Nathan; Beech, Mark; Schuster, Mathieu; Hill, Andrew

2012-01-01

398

Thermotectonic events from Eparly Proterozoic to Miocene in the Indochina craton: implication of K Ar ages in Vietnam  

NASA Astrophysics Data System (ADS)

Synkinematic mineral separates from high-grade metamorphic rocks, which were collected from the Day Nui Con Voi-Red River shear zone and the pre-Mesozoic metamorphic belt south of it, the Da Nang-Khe Sanh shear zone, and the Kontum massif in Vietnam, were dated by K-Ar method. Twenty-four analyses of hornblende, bioitite, and muscovite are clustered into four different groups: Early Proterozoic (ca. 1700-2000 Ma), Early Triassic (ca. 240-258 Ma), Early Cretaceous (115-116 Ma), and Late Oligocene-Early Miocene (24-29 Ma). The K-Ar age data in general indicate cooling ages of ductile deformations and metamorphisms in Vietnam, suggesting an overprinting of thermotectonic events in Indochina from Early Proterozoic to Tertiary, which are generally consistent with tectono-stratigraphic episodes in the region. The data demonstrate that the Indosinian orogeny in Vietnam has occurred during Earliest Triassic times, and Paleozoic orogeny (Caledonian and/or Hercynian) was not inferred by these K-Ar age data.

Ngoc Nam, Tran

1998-10-01

399

Multivariate statistical analyses of palynodebris from the Middle Miocene of the Niger Delta and their environmental significance  

SciTech Connect

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.

Oboh, F.E. (Univ. of Missouri, Rolla (United States))

1992-12-01

400

Chewing through the Miocene: an examination of the feeding musculature in the ground sloth Hapalops from South America (Mammalia: Pilosa).  

PubMed

Hapalops, a smaller-sized and early sloth of the Megatheroidea, appeared in the middle Miocene Santa Cruz formation of Argentina. This genus is part of the group from which later, larger megatheroids arose, i.e., Nothrotheriops and Megatherium. Many cranial characters support this idea; however Hapalops is not merely a smaller antecedent of the later forms. Specifically, Hapalops retains short anterior caniniform teeth, and a temporomandibular joint elevated above the cheek tooth row; a combination distinct among sloths. An elevated temporomandibular joint occurs in Bradypus, a tree sloth with anterior chisel-shaped teeth instead of caniniforms, and the tree sloth Choloepus, which is aligned with the megalonychids, has anterior caniniforms. Hapalops has an elongated zygomatic ascending process that is reminiscent of that in Bradypus; however, the Bradypus skull is extremely foreshortened while that of Hapalops is elongated, as in nothrotheres, but not deepened as in megatheres. Previous work identified many sloth cranial character complexes, and functional limitations on skull feature combinations. The unique Hapalops character patterns indicate a selective feeder with a mediolaterally oriented grinding stroke during mastication. PMID:25075299

Naples, Virginia L; McAfee, Robert K

2014-01-01

401

Chewing through the Miocene: an examination of the feeding musculature in the ground sloth Hapalops from South America (Mammalia: Pilosa)  

PubMed Central

Hapalops, a smaller-sized and early sloth of the Megatheroidea, appeared in the middle Miocene Santa Cruz formation of Argentina. This genus is part of the group from which later, larger megatheroids arose, i.e., Nothrotheriops and Megatherium. Many cranial characters support this idea; however Hapalops is not merely a smaller antecedent of the later forms. Specifically, Hapalops retains short anterior caniniform teeth, and a temporomandibular joint elevated above the cheek tooth row; a combination distinct among sloths. An elevated temporomandibular joint occurs in Bradypus, a tree sloth with anterior chisel-shaped teeth instead of caniniforms, and the tree sloth Choloepus, which is aligned with the megalonychids, has anterior caniniforms. Hapalops has an elongated zygomatic ascending process that is reminiscent of that in Bradypus; however, the Bradypus skull is extremely foreshortened while that of Hapalops is elongated, as in nothrotheres, but not deepened as in megatheres. Previous work identified many sloth cranial character complexes, and functional limitations on skull feature combinations. The unique Hapalops character patterns indicate a selective feeder with a mediolaterally oriented grinding stroke during mastication. PMID:25075299

Naples, Virginia L.; McAfee, Robert K.

2014-01-01

402

Juvenile hominoid cranium from the late Miocene of southern China and hominoid diversity in Asia  

PubMed Central

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

Kelley, Jay; Gao, Feng

2012-01-01

403

Palynostratigraphy, palaeoclimates and palaeodepositional environments of the Miocene aged Agbada Formation in the Niger Delta, Nigeria  

NASA Astrophysics Data System (ADS)

A diverse assemblage of palynomorphs dominated by terrestrially derived pollen and spores is reported from three wells penetrating the Miocene Agbada Formation. The pteridophyte and bryophyte spores which form the background assemblages in the three wells are good indicators of humid tropical climates which might have prevailed in the Niger Delta during the Miocene. The abundance and variations of climate-sensitive taxa including mangrove affiliated pollen and spore types Acrostichumsporites, Psilatricolporites crassus, Zonocostites ramonae and Graminidites annulatus representing the savannah vegetation cover indicate a complex interplay between periods of wetter and drier climates. Marine-derived dinoflagellate cysts and foraminiferal test linings are significantly present in the three wells. Taxa indicating freshwater contributions including Botryococcus spp., Chomotriletes minor, Ovoidites parvus and Pediastrum spp. are also represented numerically across the three wells. The presence of age diagnostic palynomorphs such as Crassoretitriletes vanraadshooveni, Retibrevitricolporites obodoensis, Tuberculodinium vancampoae, Zonocostites ramonae and Tuberculodinium vancampoae recovered in the three sections studied suggest a Miocene age for the investigated Agbada Formation. The proposed age is supported by the ranges of key palynomorphs in contemporaneous basins in Africa, northern South America and other parts of the World.

Bankole, Samson I.; Schrank, Eckart; Osterloff, Peter L.

2014-07-01

404

Terpenoid Compositions and Botanical Origins of Late Cretaceous and Miocene Amber from China  

PubMed Central

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

Shi, Gongle; Dutta, Suryendu; Paul, Swagata; Wang, Bo; Jacques, Frédéric M. B.

2014-01-01

405

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

PubMed Central

Abstract 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. The history of work on the Randeck Maar is briefly reviewed and these fossils placed into context with other Tertiary and living species of the genus Apis Linnaeus (Apinae: Apini). Previously unrecorded specimens from Randeck Maar were compared with earlier series in an attempt to evaluate the observed variation. A morphometric analysis of forewing venation angles across representative Recent and Tertiary species of Apis as well as various non-Apini controls was undertaken to evaluate the distribution of variation in fossil honey bees. The resulting dendrogram shows considerable variation concerning the wing venation of Miocene Apini, but intergradation of other morphological characters reveals no clear pattern of separate species. This suggests that a single, highly variable species was present in Europe during the Miocene. The pattern also supports the notion that the multiple species and subspecies proposed by earlier authors for the Randeck Maar honey bee fauna are not valid, and all are accordingly recognized as Apis armbrusteri Zeuner. PMID:21594072

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

2011-01-01

406

Late Miocene remagnetization within the internal sector of the Northern Apennines, Italy  

USGS Publications Warehouse

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.

Aiello, I.W.; Hagstrum, J.T.; Principi, G.

2004-01-01

407

Dental microwear profilometry of African non-cercopithecoid catarrhines of the Early Miocene.  

PubMed

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

Shearer, Brian M; Ungar, Peter S; McNulty, Kieran P; Harcourt-Smith, William E H; Dunsworth, Holly M; Teaford, Mark F

2015-01-01

408

First Occurrence of Platycladus from the Upper Miocene of Southwest China and Its Phytogeographic Implications  

PubMed Central

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

Li, Qi-Jia; Zhao, Zhen-Rui; Sun, Bai-Nian

2014-01-01

409

Late Miocene sedimentary environments in south-western Amazonia (Solimões Formation; Brazil)  

NASA Astrophysics Data System (ADS)

In Miocene times a vast wetland existed in Western Amazonia. Whereas the general development of this amazing ecosystem is well established, many questions remain open on sedimentary environments, stratigraphical correlations as well as its palaeogeographical configuration. Several outcrops located in a barely studied region around Eirunepé (SW Amazonas state, Brazil) were investigated to obtain basic sedimentological data. The observed deposits belong to the upper part of the Solimões Formation and are biostratigraphically dated to the Late Miocene. Vertically as well as laterally highly variable fine-grained clastic successions were recorded. Based on the lithofacies assemblages, these sediments represent fluvial deposits, possibly of an anastomosing river system. Sand bodies formed within active channels and dominant overbank fines are described (levees, crevasse splays/channels/deltas, abandoned channels, backswamps, floodplain paleosols). Lacustrine environments are restricted to local floodplain ponds/lakes. The mollusc and ostracod content as well as very light ?18O and ?13C values, measured on ostracod valves, refer to exclusively freshwater conditions. Based on palaeontological and geological results the existence of a long-lived lake (“Lake Pebas”) or any influx of marine waters can be excluded for that region during the Late Miocene.

Gross, Martin; Piller, Werner E.; Ramos, Maria Ines; Douglas da Silva Paz, Jackson

2011-08-01

410

Molluscan fauna from the Miocene sediments of Kachchh, Gujarat, India — Part 3. Gastropods  

NASA Astrophysics Data System (ADS)

Systematic description of 25 gastropod species from the Khari Nadi Formation (Aquitanian) and Chhasra Formation (Burdigalian) from the Kachchh District, Gujarat, India is given. A checklist of 116 forms including those reported by earlier researchers, emending taxonomic identifications wherever necessary, is also provided. Vredenburg had referred these two formations together as ‘the Gaj Beds of Kachchh’. He noticed the affinity of molluscs among the Miocene deposits of Kachchh and Kathiawar regions of Gujarat, and Sind province of Pakistan. He also observed that molluscs from his ‘Lower Gaj’ and ‘Upper Gaj’ Formations showed relationship respectively with the Rembang (Aquitanian) and Njalindung (Burdigalian) series of the East Indies. Aquitanian and Burdigalian ages assigned by him were later substantiated by Raju on the basis of foraminifera. Present studies corroborated that the molluscan assemblage from the Miocene rocks of Kachchh is closely related to that from the Gaj Beds of Sind and the Ashapura Clay Member of Kathiawar; besides revealing that the fauna from these three formations taken together is essentially endemic. Discovery of certain species from the Quilon Beds in the Miocene of Kachchh evinces a close affinity between these two formations. The present fauna includes five extant forms, while 29 forms have related species in the Recent fauna.

Kulkarni, Kantimati G.; Kapoor, Satarupa Bhattacharjee; Borkar, Vidyadhar D.

2010-06-01

411

Middle Miocene environmental and climatic evolution at the Wilkes Land margin, East Antarctica  

NASA Astrophysics Data System (ADS)

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