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1.
Prof.em. Henno Martin 《International Journal of Earth Sciences》1981,70(2):480-496
The glacial deposits of Gondwana are today spread over one whole hemisphere. On the re-assembled Gondwana continents they still occupy an area exceeding that of the Pleistocene glaciation. The onset of the glaciation in the different areas has not yet been dated satisfactorily. The earliest lower and middle Carboniferous glacial beds occur in the Andean belt and in eastern Australia, where high mountains may have existed at that time. During Stephanian-Sakmarian time, when the pole wandered over Antarctica, large ice sheets reached sealevel in all the major depositories. Palaeotopographical reconstructions allow the conclusion that some of the ice centres were supported by uplands which reached altitudes of up to 1,500 m above sealevel. Depending on their palaeotopographical positions the glacigenic sediments exhibit the full facies range to be expected between glaciated uplands and glaciomarine environments. There are indications that ice may have flowed from Africa into the Paraná Basin, and from Antarctica into the Great Karoo-Basin and into Australia. At least 12 advances and retreats have been recognized in the Paraná Basin. Closer to the ice centres the record is less complete. The retreats were probably more of an interstadial than an interglacial nature. There is some evidence that the final deglaciation proceeded in stages from South America over Africa to Antarctica. The ice centres were fed by moist air from the Pacific Ocean and the Tethys.
Zusammenfassung Die glazialen Ablagerungen von Gondwana sind heute über eine ganze Hemisphäre verteilt. Auch auf dem rekonstruierten Gondwana nehmen sie noch ein Gebiet ein, welches das der pleistozänen Vereisung übertrifft. Die frühesten, unter- und mittelkarbonen Vereisungsspuren finden sich im Anden-Gürtel und im Tasman-Belt in Ostaustralien, wo zu dieser Zeit hohe Gebirgsketten existiert haben können. Während des Stephan und Sakmar, als der Pol sich auf der Antarktis befand, erreichten große Inlandeis-Decken den Seespiegel in allen größeren Ablagerungsbecken. Paläotopographische Rekonstruktionen erlauben die Schlußfolgerung, daß einige der Eiszentren sich auf Hochländern mit Höhen von bis zu 1500 m befanden. Die glazialen Sedimente zeigen, abhängig von ihrer paläotopographischen Position, alle zu erwartenden Faziestypen. Es gibt Hinweise, daß Eis von Afrika in das Paraná-Becken und von Antarktika in das Große Karoo-Becken und nach Australien geflossen sein könnte, Wenigstens 12 Vorstöße und Rückzüge sind im Paraná-Becken erkannt worden. In der Nähe der Eiszentren ist die Zahl geringer. Die Rückzüge hatten wahrscheinlich mehr die Natur von Interstadialen als von Interglazialen. Es gibt Hinweise, daß das finale Abschmelzen im unteren Perm in mehreren Phasen von Südamerika über Afrika nach Antarktika fortgeschritten sein könnte. Die Eiszentren wurden durch feuchte Luftmassen vom Pazifischen Ozean und der Tethys genährt.
Résumé Les dépôts glaciaires de Gondwana sont répartis actuellement sur une hémisphère entière. Même sur le Gondwana reconstitué, ils occupent encore une surface qui dépasse celle de la glaciation pleistocène. Les traces de glaciation les plus précoces, èo- et mésocarbonifères se trouvent dans la ceinture andine et dans la ceinture tasmanienne d'Australie orientale, où des chaînes de montagnes élevées ont pu exister à cette époque. Pendant le Stéphanien et le Sakmarien, lorsque le pôle s'est trouvé dans l'Antarctique, de grandes nappes continentales de glace ont atteint le niveau de la mer dans tous les grands bassins sédimentaires. Des reconstitutions paléotopographiques permettent de conclure que quelques-uns des centres de glaciation se trouvaient dans des zones de montagnes ayant des altitudes atteignant 1500 m. Les sédiments glaciaires montrent, en fonction de leur position paléotopographique, tous les types de faciès que l'on peut attendre. D'après certaines indications, la glace aurait pu couler d'Afrique dans le bassin du Paraná et de l'Antarctique dans le grand bassin du Karoo et vers l'Australie. Au moins douze avancées et retraits ont été reconnus dans le bassins du Paraná. A proximité des centres de glaciation leur nombre est moindre. Les retraits avaient sans doute un caractère plus interstadiaire qu'interglaciaire. Certaines indications permettent de penser que la fusion finale pouvrait avoir progressé, au cours du Permien inférieur, d'Amérique du Sud vers l'Afrique puis vers l'Antarctique, en plusieurs phases. Les centres de glaciation ont été nourris par des masses d'air humides venant de l'Ocean Pacifique et de la Téthys.
. , . , , . , , . , 1,500 . , , . , Parana', — Karoo . Parana' , , 12 . . , -, , . , . , .相似文献
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Spectral analysis of deep-sea sediments indicates that the fluctuations in compositional parameters are not random fluctuations with time. Spectra show significant peaks representing periodicities in the data of 380, 1300, and 2600 years. Two of these periods are similar to periods reported in 14C fluctuations. Analysis of a paleotemperature curve from the North Atlantic shows that the characteristics of the fluctuations within interglacial and glacial stages of the climate are similar, and that the spectrum has a significant peak at 2600 years. 相似文献
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J. Kalvoda O. Babek O. Fatka J. Leichmann R. Melichar S. Nehyba P. Spacek 《International Journal of Earth Sciences》2008,97(3):497-518
The Brunovistulian terrane represents a microcontinent of enigmatic Proterozoic provenance that was located at the southern
margin of Baltica in the early Paleozoic. During the Variscan orogeny, it represented the lower plate at the southern margin
of Laurussia, involved in the collision with the Armorican terrane assemblage. In this respect, it resembles the Avalonian
terrane in the west and the Istanbul Zone in the east. There is a growing evidence about the presence of a Devonian back-arc
at the margin of the Brunovistulian terrane. The early Variscan phase was characterized by the formation of Devonian extensional
basins with the within-plate volcanic activity and formation of narrow segments of oceanic crust. The oldest Viséan flysch
of the Rheic/Rhenohercynian remnant basin (Protivanov, Andelska Hora and Horní Benesov formations) forms the highest allochthonous
units and contains, together with slices of Silurian Bohemian facies, clastic micas from early Paleozoic crystalline rocks
that are presumably derived from terranes of Armorican affinity although provenance from an active Brunovistulian margin cannot
be fully excluded either. The development of the Moravo–Silesian late Paleozoic basin was terminated by coal-bearing paralic
and limnic sediments. The progressive Carboniferous stacking of nappes and their impingement on the Laurussian foreland led
to crustal thickening and shortening and a number of distinct deformational and folding events. The postorogenic extension
led to the formation of the terminal Carboniferous-early Permian Boskovice Graben located in the eastern part of the Brunovistulian
terrane, in front of the crystalline nappes. The highest, allochthonous westernmost flysch units, locally with the basal slices
of the Devonian and Silurian rocks thrusted over the Silesicum in the NW part of the Brunovistulian terrane, may share a similar
tectonic position with the Giessen–Harz nappes. The Silesicum represents the outermost margin of the Brunovistulian terrane
with many features in common with the Northern Phyllite Zone at the Avalonia–Armorica interface in Germany. 相似文献
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晚太古代Sanukite（赞岐岩）与地球早期演化 总被引：9，自引：12，他引：9
Shirey and Hanson(1984)将某些太古代的高镁闪长岩套称为sanukite(赞岐岩),类似于日本中新世(11～15Ma)Setouchi火山岩带的高镁安山岩。Sanukitoids由闪长岩-二长闪长岩-花岗闪长岩组成,不同于TTC岩套(奥长花岗岩-英云闪长岩-花岗闪长岩)。Sanukitoids具有下列地球化学特征:富Mg,Mg~#>0.60,Ni和Cr>100μg/g,Sr和Ba>500μg/g,LREE富集(大于球粒陨石100倍),无Eu异常。高镁安山岩在太古代很少见,而其相应的侵入岩高镁闪长岩或sanukitoids,虽然数量也很少,但却是各地晚太古代地体中随处可见的。Sanukitoids的原始岩浆是交代的地幔楔部分熔融形成的,随后可能经历了广泛的分离结晶作用。TTC和sanukitoids岩套可以相伴产出,二者均与板片熔融有关,TTG与其直接有关,sanukitoids可能与其间接有关。全球Sanukitoids主要集中在晚太古代时期,可能暗示板块的消减作用在～3.0Ga以后才起了重要的作用。 相似文献
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M. E. Brookfield 《International Journal of Earth Sciences》1987,76(2):477-484
The Blaini Formation of the Lesser Himalaya has long been considered Permo-Carboniferous in age on simple lithological correlation with Gondwana Tillites in southern India. Rare, and non-repeatable finds of fossils from the type area were thought to confirm this. Recently, Lower Cambrian faunas have been recorded from the overlying Tal and Krol Formations, and possible metazoan trails recorded from the Blaini itself. In addition, the Blaini Formation is, even on a lithostratigraphic comparison, much more like other late Proterozoic glacial sequences. The term Blaini Formation should only be used for rocks of the type area — not for widely scattered glacial deposits which may or may not be correlatable with the type section. The persistent belief in the Paleozoic age of the Blaini (and adjacent formations) has for long retarded unterstanding of Lesser Himalaya stratigraphy and tectonics.
Zusammenfassung Die Blaini Formation des Niederen Himalaya wurde bisher aufgrund lithologischer Vergleiche mit Gondwana Tilliten aus Süd-Indien in das Permo-Karbon eingestuft. Seltene, nicht wiederholbare Fossilfunde schienen dieses zu bestätigen. Kürzlich wurden Faunen des Unterkambriums in den überlagernden Tal- und Krol-Formationen gefunden sowie vermutliche Metazoanspuren aus der Blaini Formation selbst. Darüberhinaus ist die Blaini Formation sogar über den lithostratigraphischen Vergleich eher mit spätproterozoischen Glazialfolgen zu vergleichen. Der Begriff Blaini Formation sollte nur für die Typlokalität verwendet werden, und nicht für ähnliche Glazialvorkommen in der weiteren Umgebung. Die fortdauernde Annahme des paläozoischen Alters der Blaini- und umgebenden Formationen hat über lange Zeit hinweg das Verständnis für die Stratigraphie und die tektonische Entwicklung des Niederen Himalayas behindert.
Résumé La formation de Blaini, dans l'Himalaya inférieur, a été jusqu'ici placée dans le Permo-Carbonifère sur la base de ses analogies lithologiques avec les tillites gondwaniennes du Sud de l'Inde. Cette attribution a semblé pouvoir Être confirmée par la découverte de quelques fossiles rares et isolés. Récemment des faunes du Cambrien inférieur ont été identifiées dans les formations surincombantes de Tal et de Krol; dans la formation de Blaini elle-mÊme des traces possibles de métazoaires ont été relevées. De plus, au seul point de vue lithologique, c'est avec les séries glaciaires du ProtérozoÏque supérieur que la formation de Blaini présente le plus de similitude. L'emploi du terme »Formation de Blaini« doit Être restreint à sa localité-type et doit Être évité pour des formations glaciaires d'autres régions, qui peuvent Être d'âges divers. L'âge paléozoÏque, attribué régulièrement jusqu'ici à la formation de Blaini et aux formations adjacentes a constitué un obstacle permanent à une bonne compréhension stratigraphique et tectonique de l'Himalaya inférieur.
, Blaini . , , , . Tal Krol , Blaini — . , . « Blaini» , , . , Blaini , .相似文献
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GUNILLA GARD 《Boreas: An International Journal of Quaternary Research》1986,15(3):217-229
Calcareous nannofossil assemblages of late Quaternary age have been investigated in short sediment cores from the eastern Arctic Ocean and the Norwegian Sea. The ages estimated in these cores are mainly based on calibration with northern North Atlantic reference material, where the first appearance of Emiliania huxleyi occurs in oxygen isotope stage 8 at 264,000 years B.P., and its sharp increase in relative abundance occurs in oxygen isotope stage 4 at 61,000 years B.P. Minor amounts of reworked Cretaceous and Tertiary specimens are present throughout the cores. Intervals where nannofossils occur in abundance represent warmer interstadial or interglacial conditions, whereas barren intervals represent glacial conditions. Holocene open water conditions are recognized by high frequencies of Coccolithus pelagicus . Sediment accumulation rates show considerable variation and range between 1 and 13 cm/ka. 相似文献
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Angela L. Lamb Silvia Gonzalez David Huddart Sarah E. Metcalfe Christopher H. Vane Alistair W.G. Pike 《Quaternary Science Reviews》2009,28(19-20):2000-2016
The Tepexpan Palaeoindian skeleton was discovered in 1947 close to the former Lake Texcoco margin, in the Basin of Mexico. The find has been the object of considerable interest and discussion over the last 60 years regarding its real age and archaeological interpretation. Here we report new AMS radiocarbon dates associated with the sedimentary succession at Tepexpan with ages between 19,110 ± 90 and 612 ± 22 14C years BP and a new uranium-series date for the skeleton with an age of 4700 ± 200 years BP that indicates a mid Holocene age. The sedimentary succession was studied in detail using: stable isotopes, diatoms, organic geochemistry and tephrochronology. The multi-proxy evidence suggests large changes around the margins of Lake Texcoco in terms of the balance between aquatic and terrestrial plants, C3 and C4 plants, saline, alkaline and freshwater conditions, volcanic activity, marginal reworking of lake sediments and input from the drainage basin through the late Pleistocene–late Holocene. These changes had large impacts on the prehistoric human populations living by the lake shores since the late Pleistocene in the Basin of Mexico. 相似文献
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对晚第四纪钱塘江下切河谷内SE2孔沉积物重矿物和稀土-微量元素进行系统分析,并与邻区长江沉积物相应特征进行对比。结果显示: (1)晚第四纪钱塘江下切河谷充填物中河床(U5)、河漫滩(U4)和古河口湾(U3)沉积物的重矿物组合为赤褐铁矿-磁铁矿-锆石-白钛石-锐钛矿;微量元素中的铁族元素、大离子亲石元素和高场强元素与平均大陆上地壳(UCC)相近,且大离子亲石元素和大部分高场强元素与北美页岩(NASC)相近,在Th/Co-Cr/Th投点图中靠近钱塘江物源区,远离现代长江沉积物投点区;稀土元素球粒陨石和NASC标准化曲线与钱塘江沉积物特征相似,不同于现代长江沉积物。(2)近岸浅海(U2)和现代河口湾(U1)沉积物的重矿物组合为绿帘石-辉石-角闪石-石榴石-榍石-金红石-电气石;微量元素具有与UCC较为相近或富集的铁族元素,大离子亲石元素和高场强元素相对亏损,且与NASC相比,铁族和高场强元素明显亏损,大离子亲石元素亏损较弱,在Th/Co-Cr/Th投点图中主要落于长江和钱塘江来源沉积物之间;稀土元素在球粒陨石和NASC标准化曲线中,配分模式与现代长江沉积物极为相似。(3)U5、U4和U3单元具有与U1和U2单元不同的沉积物来源: 前者母岩主要为长英质中酸性火成岩,为古钱塘江提供; 而后者沉积物主要来源于中基性物源区,由长江提供,同时上游钱塘江也提供了部分沉积物。可见,长江沉积物自近岸浅海沉积时期开始大量进入到钱塘江下切河谷内,为钱塘江下切河谷的沉积环境演化提供了重要物质基础。 相似文献
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《International Geology Review》2012,54(12):2091-2101
In the Kuznetsk basin, south-central Siberia, regression of marine conditions promoted simultaneous existence of many environments during Carboniferous and Permian times. Different sequences of fades in different areas complicate correlation. Floral, faunal and lithologic data have been mapped to determine succession of biologic complexes for four intervals of late Paleozoic time: 1) middle Ostrog suite (maximum marine transgression); 2) middle Alykayeva subsuite of the lower Balakhonikha suite (maximum Balakhonikha coal formation); 3) upper Kuznetsk and lower Il'ya suites (beginning of second stage of coal formation); 4) middle Uskat subsuite of Il'ya suite. These intervals were selected because they correspond to the peak development of conditions typical of their stratigraphic subdivisions, they are most easily correlated, and contain the most information. — Nicholas Hotton, III. 相似文献
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We propose a chronology of late Wisconsinan glacial fluctuations in middle North America, from Alberta to Wisconsin, based on radiocarbon dates derived solely from wood. Previous chronologies of the southwestern margin of the North American Continental Ice Sheet have depended to a considerable degree on radiocarbon dates from fine-grained organic sediment. This material is commonly contaminated with older carbon, resulting in chronologic confusion. By using only dates from wood, much of the confusion disappears. However, because of the scarcity of wood dates, only four of the sixteen identified fluctuations are accurately dated: an advance into Iowa about 14,000 to 13,500 BP, an advance into South Dakota and Iowa about 12,300 BP, an advance into the Lake Michigan basin about 11,700 BP, and an advance into the Lake Superior basin about 9900 BP. In addition, the beginning of late Wisconsinan glaciation, before 20,000 BP, is fairly well documented. None of the fluctuations in the western part of the region are accurately dated. 相似文献
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Estelle Leroux Daniel Aslanian Marina Rabineau Romain Pellen Maryline Moulin 《地学学报》2018,30(3):207-214
A review of geological and geophysical observations points towards a worldwide kinematic change at around 6 Ma. The synchronicity of many manifestations (tectonics, magmatism, kinematics, ecological events, among others) at ~6 Ma, similar to those recognized from time to time on the geological time‐scale, argues for a global geodynamic event that has led to many regional consequences on Earth's surface. In particular, we propose that this global event was the main trigger for the three fold increase in sediment deposits in the world ocean over the last ~5 Ma, but also for the onset of the Messinian Salinity Crisis in the Mediterranean area, one of the most severe ecological crises in the Earth's history. We suggest this Messinian revolution to be the last occurrence of cyclic successions of global events. 相似文献
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本文根据野外地质地貌调查,结合卫星影像解译和钻孔资料的分析认为,邯郸—邢台断裂是一条晚第四纪以来活动的断裂。根据断裂走向、活动时代及活动性质的变化,可将该断裂分为三段。临城—永年和永年—磁县段为全新世活动断裂,活动性质为右旋正断,晚更新世断裂的垂直滑动速率为0.25mm/a,全新世垂直滑动速率为0.47mm/a。磁县—安阳段为晚更新世时期活动断裂,活动性质为右旋正断,垂直运动速率为0.22mm/a,但全新世没有活动。 相似文献
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V. G. Trifonov 《Geotectonics》2013,47(6):418-430
It has been shown for particular seismic zones and the Alpine-Himalayan Orogenic Belt as a whole that in addition to Fedotov cycles, the long-period hypercycles of seismicity are distinguished. Long-period variations were revealed in Syria, in southern and central segments of the El-Ghab Fault Zone of the Dead Sea Transform (EG DST), and at the southwestern end of the East Anatolian Fault Zone (EAFZ). The EG DST demonstrates a ～1800-year hypercycle with a maximum in the 3rd-7th and the 19th-20th centuries A.D. To reveal variations in seismicity in the entire central part of the orogenic belt, we have corrected evidence for historical earthquakes, taking into account the probability of missing events and the area of their regular recording domains. As a result, we displayed maximums of seismic energy release from the mid-17th to mid-20th century A.D.; from the mid-4th to the end of the 6th century; and in the 15th-13th centuries B.C. When interpreting hypercycles, it is important to keep in mind that variation of seismicity in EG DST correlates with variation of the rate of elastic deformation accumulation, probably reflecting variability of the stress-and-strain state in the region and of velocity of tectonic movements in active domains. After additional investigations, hypercycles could be taken into account for to refine the seismic hazard estimate. 相似文献
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Alan L. Bryan 《Quaternary Research》1973,3(2):237-256
After a summary assessment of certain selected early man sites in various parts of America, the environment of the Venezuelan coastal plain is discussed in order to evaluate the stratigraphy and radiometric dating of the Taima-Taima site, near Coro, Venezuela, where mammals, many now extinct, were killed by people making El Jobo points about 13,000 years ago.Potentially important areas in Peru, Chile and Brazil are mentioned. Certain problems in the models and interpretation of South American paleoclimates are pointed out.The presence of at least four different bifacially flaked stone projectile point traditions in widely separated and environmentally diverse parts of America between 11,000 and 13,000 yr ago suggests that the immediate cultural antecedents of these traditions were essentially independent of one another. From this it is argued that several early American flaked-stone point traditions developed indigenously in America from technological bases which were present in the Old World Middle Paleolithic. 相似文献
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A total of 17 brachiopod species belonging to 15 genera are recorded from a limestone block of about 3×4 km2 in the Indus–Tsangbo suture zone at Xiukang in Lhaze County of Tibet. The brachiopod fauna generally indicates a Late Guadalupian age (late Wordian–Capitanian, late Middle Permian) based on its association with the Timorites-bearing ammonoid fauna and the presence of the brachiopod Urushtenoidea crenulata. Palaeobiogeographically, the fauna exhibits transitional/mixed characters between the warm-water Cathaysian and cold to temperate Gondwanan faunas and may have developed on a carbonate build-up or seamount on the oceanic crust. 相似文献