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1.
The origin of the genus Bos is a debated issue. From ∼ 0.5 Ma until historic times, the genus is well known in the Eurasian large mammal assemblages, where it is represented by Bos primigenius. This species has a highly derived cranial anatomy that shows important morphological differences from other Plio-Pleistocene Eurasian genera of the tribe Bovini such as Leptobos, Bison, Proamphibos-Hemibos, and Bubalus. The oldest clear evidence of Bos is the skull fragment ASB-198-1 from the middle Pleistocene (∼ 0.6-0.8 Ma) site of Asbole (Lower Awash Valley, Ethiopia). The first appearance of Bos in Europe is at the site of Venosa-Notarchirico, Italy (∼ 0.5-0.6 Ma). Although the origin of Bos has traditionally been connected with Leptobos and Bison, after a detailed anatomical and morphometric study we propose here a different origin, connecting the middle Pleistocene Eurasian forms of B. primigenius with the African Late Pliocene and early Pleistocene large size member of the tribe Bovini Pelorovis sensu stricto. The dispersal of the Bos lineage in Western Europe during middle Pleistocene times seems to coincide with the arrival of the Acheulean tool technology in this continent. 相似文献
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Wolfgang Kiesl Christian Koeberl Wilfried Körner 《International Journal of Earth Sciences》1990,79(2):327-335
The major and trace element geochemistry of magnesite and dolomite samples from alternating rock masses at the Oberdorf/Laming (Styria, Austria) mineralization has been studied. The rare earth elements (REE) are considered to be of importance for the discussion of the origin of sparry magnesite deposits. The Al and REE contents are positively correlated, indicating a clay component as the main source for REE in the magnesites and their precursor rocks. Our data support the view that the Oberdorf and probably other magnesite mineralizations in the Eastern Alps have been formed by metasomatism. Through this process calcite (which was deposited by sedimentation in a marine environment) underwent dolomitization. Subsequently, Mg-rich solutions circulating through the rock masses formed the magnesite bodies.During the formation of the dolomites and the conversion to magnesites, the REE patterns of the original carbonates remained unchanged. The magnesites exhibit patterns that are very similar to sedimentary carbonates (which contain a REE-bearing clay component). Magnesites of purely sedimentary origin, formed in a predominantly evaporitic environment, should have lower total REE contents and different patterns due to the short residence times of these elements in seawater. Analyses of talc pseduomorphs after magnesite indicate as well that the REE patterns are not significantly altered during the talcification. The Mg-rich solutions that led to the formation of the magnesites have probably been derived from serpentinites below the gneiss complexes of eastern Styria and the South Penninic units of the Tauern window.
Zusammenfassung Die Haupt- und Spurenelementgeochemie von Magnesit- und Dolomitproben, die aus alternierenden Gesteinsstöcken in der Magnesitmine von Oberdorf/Laming (Steiermark, Österreich) stammen, wurde untersucht. Besonderes Augenmerk wurde dabei auf die Geochemie der Seltenen Erdelemente (REE) gelegt, da diese für Aussagen über die Entstehung der Magnesitlagerstätten von besonderer Bedeutung sind. Eine positive Korrelation zwischen den Al und REE-Gehalten deutet darauf hin, daß der Hauptteil der REE einer Tonkomponente entstammt. Die Daten unterstützen eine metasomatische Entstehung der Spatmagnesite der Oberdorfer Lagerstätte und anderer Ostalpiner Lagerstätten. Sedimentär angelegter Kalzit wird dabei über Dolomit mit Mg-reichen Lösungen in Magnesit umgewandelt.Während der Metasomatose bleiben die chondritnormierten REE-Verteilungen der Ausgangskarbonate relativ unverändert erhalten. Die so entstandenen Spatmagnesite weisen Verteilungsmuster auf, die jenen der sedimentären Karbonate, aus denen sie entstanden sind, entsprechen. Rein sedimentär entstandene Magnesite werden praktisch nur in evaporitischem Milieu gebildet und sollten infolge der kurzen Verweilzeit dieser Elemente im Meerwasser wesentlich niedrigere REE-Gehalte und andere Verteilungsmuster aufweisen. Analysen einer Talkpseudomorphose zeigen, daß sich die REE-Verteilungsmuster auch bei der metasomatischen Talk-bildung nicht wesentlich ändern. Die Mg-reichen Lösungen, die zur Bildung der Magnesite notwendig waren, entstammen vermutlich tiefliegenden Sepentiniten, auf die es Hinweise im Untergrund der oststeirischen Gneisskomplexe und des südpenninischen Tauernfensters gibt.
Résumé Cette note présente les résultats d'une étude géochimique des éléments majeurs et en trace d'échantillons de magnésite et de dolomite qui se présentent en masses alternées dans la mine de magnésite de Oberdorf/Laming (Steiermark, Autriche). Une attention particulière a été apportée aux terres rares, considérées comme fournissant des arguments importants dans la discussion de l'origine des gisements. Les teneurs en Al et en terres rares montrent une corrélation positive, ce qui permet de rapporter à un composant argileux la source principale des terres rares. Les résultats obtenus plaident en faveur d'une origine métasomatique des minéralisations en magnésite d'Oberdorf et d'autres endroits des Alpes orientales. Au cours de ce processus, la calcite, d'origine sédimentaire marine, a été le siège d'une dolomitisation avec, subséquemment, formation de corps de magnésite grâce à la circulation de solutions riches en Mg.Au cours de la métasomatose, la distribution des terres rares des carbonates originels n'est pas modifiée: les magnésites montrent des répartitions très semblables à celles des carbonates sédimentaires (lesquels renferment un constituant argileux porteur des terres rares). Des magnésites d'origine purement sédimentaires, formées en milieu évoporitique, doivent présenter un contenu total en terres rares moins élevé et une distribution différente de ces éléments, eu égard à la brièveté de leur séjour dans l'eau de mer. Des analyses de pseudomorphoses de magnésite en talc montrent de même que la distribution des terres rares n'est pas modifiée de manière significative au cours de la talcification. Les solutions riches en Mg responsables de la formation de la magnésite sont probablement dérivées de serpentines situées sous les complexes gneissiques de Styrie et les unités penniques méridionales de la fenêtre des Tauern.
dorf/Laming'a (, ) . , . , . , , - . . . .. , , . , , , , ; . , . , , , , , - - .相似文献
3.
The phylogenetic origin of the Sepiida is still unclear. The presumed derivation from diplobelid belemnoids can be tested by comparison of their initial chambers (protoconchs). The first investigation of a juvenile phragmocone of the diplobelid Conoteuthis hayakawai from the Cenomanian of Hokkaido (northern Japan) yielded surprising insights into the internal protoconch morphology of the Diplobelida. The Conoteuthis protoconch exhibits in many aspects a mosaic of the belemnitid and the spirulid protoconch types. Whereas the sepiid protoconch represents most probably a modification of the spirulid type, the Conoteuthis protoconch is unique in having a closed (imperforated) proseptum. Apart from this, Conoteuthis differs in many other characters from the earliest sepiids (Ceratisepia, Belosepia), which makes a closer relationship unlikely. 相似文献
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PIRKKO UKKONEN LEMBI LÕUGAS ILGA ZAGORSKA LIGITA LUKEVICA ERVINS LUKEVICS LINAS DAUGNORA HÖGNE JUNGNER 《Boreas: An International Journal of Quaternary Research》2006,35(2):222-230
A total of 45 subfossil reindeer (Rangifer tarandus) antlers and bones - artefacts excluded - have been found over the years in the Baltic countries of Estonia, Latvia and Lithuania. The relatively high number of specimens suggests a stable residence of the species in the eastern Baltic region. For the first time, 12 of these finds were radiocarbon-dated. The ages of the samples range between 12 085 and 9970 14C yr BP (14 180-11 280 cal. yr BP), and cover the Lateglacial and early Holocene, a time period during which climatic conditions shifted from periglacial to temperate. The dates suggest a rapid colonization of the area during the deglaciation period and a local extinction around the Pleistocene-Holocene boundary. The results of the study do not support the theory that the recent wild reindeer populations of northern Europe had their origin in the Late Weichselian reindeer populations of the eastern Baltic region. 相似文献
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R. Lee Lyman 《Quaternary Research》2011,75(1):176-182
A mandible identified as noble marten (Martes americana nobilis) recovered from sediments dating to 11,800 cal yr BP and a humerus identified as M. a. cf. nobilis recovered from sediments dating from 13,100 to 12,500 cal yr BP at the Marmes Rockshelter archaeological site in southeastern Washington represent the first record of this taxon in the state. Mammalian taxa associated with the Marmes Rockshelter noble marten represent a diversity of open mesic habitats corroborating earlier analyses of other records of the noble marten in the western United States and exemplify how paleozoologists determine the ecology and environmental predilections of extinct taxa. The recovery site represents the topographically lowest record of this species in western North America and the farthest north record in the United States. Future research should examine known late-Quaternary Martes spp. remains from British Columbia and Alberta to fill in the 2200-km geographic gap in the known distribution of this taxon between a record in the northern Yukon and those in the western United States, and to refine our knowledge of noble marten paleoecology. 相似文献
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Julie SucharováIvan Suchara Clemens Reimann Rognvald BoydPeter Filzmoser Peter Englmaier 《Applied Geochemistry》2011,26(7):1205-1214
Lead concentrations were determined in samples of soil B-horizon (N = 258), forest-floor humus (O-horizon, N = 259), grass (Avenella flexuosa, N = 251) and spruce (Picea abies, N = 253) needles (2nd year) collected at the same locations evenly spread over the territory of the Czech Republic at an average density of 1 site/300 km2. Median Pb concentrations differ widely in the four materials: soil B-horizon: 27 mg/kg (3.3-220 mg/kg), humus: 78 mg/kg (19-1863 mg/kg), grass: 0.37 mg/kg (0.08-8 mg/kg) and spruce needles: 0.23 mg/kg (0.07-3 mg/kg). In the Pb distribution maps for humus, grass and spruce a number of well-known Pb-contamination sources are indicated by unusually high concentrations (e.g., the Pb smelter at Pribram, the metallurgical industry in the NE of the Czech Republic and along the Polish border, as well as the metallurgical industry in Upper Silesia and Europe’s largest coal-fired power plant at Bogatynia, Poland). The ratio 206Pb/207Pb was determined in all four materials. The median value of the 206Pb/207Pb isotope ratio in the soil B-horizon is 1.184 (variation: 1.145-1.337). In both humus and grass the median value for the 206Pb/207Pb isotope ratio is 1.162 (variation: 1.130-1.182), in spruce needles the median ratio is 1.159 (variation: 1.116-1.186). In humus, grass and spruce needles the known contamination sources are all marked by higher 206Pb/207Pb isotope ratios in the maps. Furthermore, the soil B-horizon, humus, grass and spruce needles show distinctly different spatial distribution patterns of the 206Pb/207Pb isotope ratios. The B-horizon does not provide a viable background value for metal concentrations in the O-horizon or plant materials. None of the maps provides evidence for the importance of traffic-related emissions for the observed isotope ratios at the scale of the Czech Republic. 相似文献
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James F. Humpula Hasand Gandhi Angela K. Walker James J. Smith R. George Corner 《Geochimica et cosmochimica acta》2007,71(24):5956-5967
Ancient DNA sequences offer an extraordinary opportunity to unravel the evolutionary history of ancient organisms. Protein sequences offer another reservoir of genetic information that has recently become tractable through the application of mass spectrometric techniques. The extent to which ancient protein sequences resolve phylogenetic relationships, however, has not been explored. We determined the osteocalcin amino acid sequence from the bone of an extinct Camelid (21 ka, Camelops hesternus) excavated from Isleta Cave, New Mexico and three bones of extant camelids: bactrian camel (Camelus bactrianus); dromedary camel (Camelus dromedarius) and guanaco (Llama guanacoe) for a diagenetic and phylogenetic assessment. There was no difference in sequence among the four taxa. Structural attributes observed in both modern and ancient osteocalcin include a post-translation modification, Hyp9, deamidation of Gln35 and Gln39, and oxidation of Met36. Carbamylation of the N-terminus in ancient osteocalcin may result in blockage and explain previous difficulties in sequencing ancient proteins via Edman degradation.A phylogenetic analysis using osteocalcin sequences of 25 vertebrate taxa was conducted to explore osteocalcin protein evolution and the utility of osteocalcin sequences for delineating phylogenetic relationships. The maximum likelihood tree closely reflected generally recognized taxonomic relationships. For example, maximum likelihood analysis recovered rodents, birds and, within hominins, the Homo-Pan-Gorilla trichotomy. Within Artiodactyla, character state analysis showed that a substitution of Pro4 for His4 defines the Capra-Ovis clade within Artiodactyla. Homoplasy in our analysis indicated that osteocalcin evolution is not a perfect indicator of species evolution. Limited sequence availability prevented assigning functional significance to sequence changes. Our preliminary analysis of osteocalcin evolution represents an initial step towards a complete character analysis aimed at determining the evolutionary history of this functionally significant protein. We emphasize that ancient protein sequencing and phylogenetic analyses using amino acid sequences must pay close attention to post-translational modifications, amino acid substitutions due to diagenetic alteration and the impacts of isobaric amino acids on mass shifts and sequence alignments. 相似文献
11.
R. Tribuzio M. F. Thirlwall B. Messiga 《Contributions to Mineralogy and Petrology》1999,136(1-2):48-62
The origin of the Sondalo gabbroic complex has been unravelled by means of a petrological study of the least evolved rocks,
troctolites to norites containing up to 20% of anhedral clinopyroxene and titanian pargasite. Pyroxenes and titanian pargasite
from the troctolites have higher Mg, Al and Cr, and lower Mn than those from the norites, whereas plagioclase does not show
systematic compositional variations (An ca. 65 mol%). The variation trend of anorthite content of plagioclase versus the forsterite
content of olivine differs from that of arc-related gabbroic rocks. Plagioclase, clinopyroxene, orthopyroxene and titanian
pargasite were analyzed for REE and selected trace elements by ion microprobe. Application of crystal/liquid partition coefficients
to trace element mineral compositions suggests that the parental liquids of both troctolites and norites had tholeiitic affinity
and were slightly LREE and LILE enriched relative to N-MORB. A troctolite and a norite give Sm-Nd mineral isochron ages of
300 ± 12 Ma and 280 ± 10 Ma. Plagioclase-amphibole Rb-Sr isochron ages are 266 ± 10 Ma and 269 ± 16 Ma for the same rock samples,
and they are interpreted to represent cooling ages. The Nd-Sr-O isotopic compositions indicate that a substantial crustal
contribution was involved in the petrogenesis of the norite, which has low ɛNd(290 Ma), high 87Sr/86Sr(290 Ma) and high δ18OPx (−2.6, 0.7057 and +7.9‰, respectively) compared with the troctolites. We thus conclude that the troctolite/norite association
formed by concomitant fractional crystallization and crustal assimilation. The somewhat elevated δ18OCpx (+6.4‰) and the relatively low forsterite contents in olivine suggest that the parental liquids of the troctolites had already
been evolved through an AFC type process. The ɛNd(290 Ma) and 87Sr/86Sr(290 Ma) of these rocks (ranging from +2.8 to +4.4 and from 0.7037 to 0.7040, respectively) probably do not reflect the
ɛNd and Sr isotopic compositions of their mantle source, and it is thus unclear whether the primary melts were derived from a
slightly enriched or from a depleted mantle source. The Sondalo gabbroic complex was most likely associated with the post-Variscan
gabbroic complexes of the Alpine belt. These gabbroic complexes can be ascribed to the intrusion at different crustal levels
of tholeiitic mantle-derived melts and were emplaced in the time span of 300–270 Ma.
Received: 14 September 1998 / Accepted: 4 January 1999 相似文献
12.
Xianyu HuangPhilip A. Meyers Weichao WuChenglin Jia Shucheng Xie 《Organic Geochemistry》2011,42(2):156-165
The potential significance of the contributions of long chain iso and anteiso monomethyl alkanes (LC MMAs) from plants of the Lamiaceae, a family that includes many culinary and aromatic herbs of cultural value, to sediments and soil has been evaluated by analyzing 21 specimens from 16 species of Lamiaceae from different environmental settings in Hubei Province, central China, and comparing the results with those from tobacco plants, which are established to be rich in these compounds. Odd numbered iso-alkanes (i-C25 to i-C36) and even numbered anteiso-alkanes (a-C25 to a-C36) are abundant in the Lamiaceae (1.9-23.2% and 0.9-23.8% of total alkanes, respectively). The proportions of LC MMAs are relatively high and comparable to those in the tobacco plant. However, chain lengths in the Lamiaceae are longer than those in tobacco plants and compound-specific δ13C values are more negative than in the tobacco plants, potentially allowing distinction of their different origins. The results imply that Lamiaceae, in addition to some other land plants, can be important sources of LC iso- and anteiso-alkanes in sediments and soils. 相似文献
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Aaron W. Hunter Neil D.L. Clark 《Proceedings of the Geologists' Association. Geologists' Association》2009,120(1):76-78
A single stem section (pluricolumnal) belonging to a post-Palaeozoic crinoid (sea lily) is reported from a small outcrop of Lower Jurassic Lias Group strata exposed in low cliff near Dunrobin Castle. This is the first Jurassic crinoid recorded from Eastern Scotland and the small fragment has enough diagnostic characters to be assigned to the species Isocrinus cf. robustus; a crinoid found commonly in the Lower Jurassic of England. The Scottish form collected has unusual morphology that is atypical of the genus. 相似文献
15.
New records of Jefferson's ground sloth (Megalonyx jeffersonii) and elk-moose (Cervalces scotti) from Lang Farm provide the first precise temporal correlation of these taxa with the specific environments inhabited by them near the time of their extinction. Six AMS 14C measurements establish an age of 11,405 ± 50 14C yr B.P. for Lang Farm Cervalces and an age of 11,430 ± 60 or 11,485 ± 40 14C yr B.P. for the Megalonyx. These measurements represent the youngest 14C dates for these two genera based on direct dating. Comparison of the dates with pollen data from northern Illinois indicates that these species inhabited a nonanalog environment that was transitional from mid-latitude tundra to mixed conifer and deciduous woodland. Although spruce (Picea sp.) was dominant, it was less abundant than prior to 12,500 14C yr B.P. The presence of black ash (Fraxinus nigra) and fir (Abies sp.) indicates a wet climate and heavy winter precipitation. This may have been the preferred habitat for Cervalces because of its narrow geographic range. However, this habitat type was only one of many occupied by Megalonyx as indicated by its broad geographic distribution. 相似文献
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Fossil remains of Euceratherium collinum (extinct shrub-ox) have been found throughout North America, including the Grand Canyon. Recent finds from the Escalante River Basin in southern Utah further extend the animal's range into the heart of the Colorado Plateau. E. collinum teeth and a metapodial condyle (foot bone) have been recovered in association with large distinctively shaped dung pellets, a morphology similar to a ‘Hershey's Kiss’ (HK), from a late Pleistocene dung layer in Bechan Cave. HK dung pellets have also been recovered from other alcoves in the Escalante River Basin including Willow and Fortymile canyons. Detailed analyses of the HK pellets confirmed them to be E. collinum and indicate a browser-type diet dominated (> 95%) by trees and shrubs: Artemisia tridentata (big sagebrush), Acacia sp. (acacia), Quercus (oak), and Chrysothamnus (rabbit brush). The retrieval of spring and fall pollen suggests E. collinum was a year-round resident in the Escalante River Basin. 相似文献
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青藏高原积雪范围和雪深/雪水当量遥感反演研究进展及挑战 总被引:1,自引:0,他引:1
积雪是地表特征的重要参数,对辐射收支、气候和长期天气变化均有重要影响。雪本身又是一个重要的天气现象和水文气象参数,过量的降雪也会带来严重的雪灾,如牧区雪灾、雪崩和融雪洪水灾害等。因此对积雪的监测,尤其是对山区的积雪监测,具有多方面的意义。利用卫星遥感技术监测积雪已有50余年的历史,并已形成了系列业务产品。青藏高原平均海拔超过4 000 m,该地区的积雪具有重要的水文、气候和生态环境意义。由于地形复杂,人迹罕至,地面观测站点稀少,受较强太阳辐射的影响,积雪消融迅速、区域差异消融以及风吹雪等因素导致积雪分布破碎化严重,对使用遥感资料监测该地区的积雪造成的极大的困难和不确定性。随着国内外传感器技术的不断发展,光学和被动微波遥感数据的同步获取技术已经非常成熟,综合利用光学遥感数据高空间分辨率和被动微波数据不受云干扰的特点,结合机器学习、无人机等技术,将环境参数加入反演模型中,有助于提高青藏高原积雪参数反演精度。 相似文献
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N.A. Gibsher A.A. Tomilenko A.M. Sazonov T.A. Bul’bak M.O. Khomenko M.A. Ryabukha E.O. Shaparenko S.A. Sil’yanov N.A. Nekrasova 《Russian Geology and Geophysics》2018,59(8):983-996
The Eldorado low-sulfide gold-quartz deposit, with gold reserves of more than 60 tons, is located in the damage zone of the Ishimba Fault in the Yenisei Ridge and is hosted by Riphean epidote-amphibolite metamorphic rocks (Sukhoi Pit Group). Orebodies occur in four roughly parallel heavily fractured zones where rocks were subject to metamorphism under stress and heat impacts. They consist of sulfide-bearing schists with veins of gray or milky-white quartz varieties. Gray quartz predominating in gold-bearing orebodies contains graphite and amorphous carbon identified by Raman spectroscopy; the contents of gold and amorphous carbon are in positive correlation. As inferred from thermobarometry, gas chromatography, gas chromatography-mass spectrometry, and Raman spectroscopy of fluid inclusions in sulfides, carbonates, and gray and white quartz, gold mineralization formed under the effect of reduced H2O-CO2-HC fluids with temperatures of 180 to 490 °C, salinity of 9 to 22 wt.% NaCl equiv, and pressures of 0.1 to 2.3 kbar. Judging by the presence of 11% mantle helium (3He) in fluid inclusions from quartz and the sulfur isotope composition (7.1-17.4‰ δ34S) of sulfides, ore-bearing fluids ascended from a mantle source along shear zones, where they “boiled”. While the fluids were ascending, the metalliferous S- and N-bearing hydrocarbon (HC) compounds they carried broke down to produce crystalline sulfides, gold, and disseminated graphite and amorphous carbon (the latter imparts the gray color to quartz). Barren veins of milky-white quartz formed from oxidized mainly aqueous fluids with a salinity of < 15 wt.% NaCl equiv at 150-350 °C. Chloride brines (> 30 wt.% NaCl equiv) at 150-260 °C impregnated the gold-bearing quartz veins and produced the lower strata of the hydrothermal-granitoid section. The gold mineralization (795-710 Ma) was roughly coeval to local high-temperature stress metamorphism (836-745 Ma) and intrusion of the Kalama multiphase complex (880-752 Ma). 相似文献