Tibetan Uplift Research Articles

Provenance of the upper Miocene–Pliocene Red Clay deposits of the Chinese loess plateau

A clear understanding of the provenance of late Cenozoic Chinese loess and the underlying Red Clay deposits will shed light on the history and mechanisms of Asian aridification. Although much progress has been made in understanding the source of Quaternary loess on the Chinese Loess Plateau (CLP), the provenance of the underlying upper Miocene–Pliocene Red Clay sequence is largely unknown. Here we present the first provenance history of the Red Clay sequence based on zircon U–Pb ages from the central CLP. Visual and statistical analyses of the U–Pb age populations and comparison with results from potential source regions reveals that (1) the lowermost Red Clay of the late Miocene (depositional age of ∼8 Ma) is likely sourced from the nearby Liupan Mountains and the Qaidam Basin; (2) the middle Red Clay (5.5–4 Ma) of the early-mid Pliocene is sourced mainly from the Taklamakan desert, transported via lower-level westerly winds; (3) the upper Red Clay of the late Pliocene (∼3 Ma) is sourced from mixed areas, although western source materials from middle-northern Tibetan plateau (including Qaidam Desert sediments and materials eroded from the Qilian Mountains) sediments appear to dominate; and (4) the Quaternary loess is also sourced from mixed source regions, albeit with dominant northern CLP proximal desert sediments transported via winter monsoon winds, which in turn may be transported from mountain source regions of the northeastern Tibet and Gobi Altai via major river systems. This long term shift in sources suggests a progressive eastward aridification during the Pliocene in Asia with the specific timing of provenance shifts synchronous with large-scale climatic transitions and Tibetan uplift, demonstrating that Asian desertification is controlled by both factors.

In Situ Measurements and Comprehensive Research on the Present Crustal Stress of Northern South China Sea

AbstractIt is necessary for developing of ocean resources, safety evaluation of geological environment and engineering to understand the status and distribution of present crustal stress in the northern South China Sea. The nature conditions restrict the research on the crustal stress of the whole South China Sea, whose characters and controlling factors are not clear. In situ stress measurement is a useful way to get the stress magnitude and direction. The stress direction can be got through the logging FMI data in ocean oil field. The numerical modeling can extrapolate the stress status and distribution in the interested area under the constraint of the in situ measured stress, FMI deduced stress and the plate tectonic environment. The west bound of northern South China Sea is Red River Fault‐Eastern Vietnam strike slip large Fault which is controlled by the collision of India plate and Euro‐Asia plate and the uplift of Tibet. The east bound of northern South China Sea is Manila trench, which have three different tectonic stress sections, plate collision near Taiwan and near Luzon, and extension between Taiwan and Luzon induced by South China Sea subduction under the Philippines plate. The authors measured in situ the magnitude and direction of stress in Ledong county, Hainan province through hydraulic fracturing, where the exposed rock body is intact and the landform is gentle. The measured rock in well is intact and the curve of measured pressure is fit to the standard, which shows that the measured stress is reliable. The optimal direction of measured maximum stress is NW‐NWW. According to the Byerlee criteria, the measured stress cannot induce the active fault to be reactivated recently. The logging FMI interpretation of marginal oil basin in the northern South China Sea shows that the optimal direction of maximum principal stress is NW‐NNW in Yinggehai basin, and NNW in Qiongdongnan basin. Constrained by the in situ measured stress and the focal mechanism the numerical modeling shows that the crustal stress in northern South China Sea is characterized by the different stress status in different zone due to India plate, Euro‐Asia plate and Philippine plate playing different role. In the area near Taiwan the crustal stress is dominated by the collision of Philippe plate and Euro‐Asia plate, and the direction of maximum principal stress is E‐W. Along marginal northern South China Sea the crustal stress is influenced by extension induced by the Euro‐Asia plate subduction under the Philippine plate at the Manila trench, and the maximum principal stress gradually turns to S‐N and NW.

Tibet forcing Quaternary stepwise enhancement of westerly jet and central Asian aridification: Carbonate isotope records from deep drilling in the Qaidam salt playa, NE Tibet

The vast Asian arid inland under the westerlies exerts great impacts on global climatic change. However, its evolution history and its relation with the westerlies, Tibet uplift and global change are still unknown. Here we present continuous carbonate isotope records from a near thousand meter deep drilling core in the Qaidam salt playa, NW China. They reveal an evident long-term persistent aridification of Asian inland since about 1.2Ma, followed by an accelerated drying since about 0.6Ma. We suggest that global cooling, especially cooling in the high latitudes of the Northern Hemisphere, might be the key driving force for this long-term persistent aridification of the Asian inland since about 1.2Ma. While the rapid uplift of the Tibetan Plateau in the mid-Pleistocene (called Kunhuang Movement) might have played an important role to the desiccation of the Asian since about 0.6Ma through enhancing and bending the westerly jet and its associated ascending flow and blocking the moisture input from the westerlies and monsoons.

The origin of Eurasian Mammoth Faunas (Mammuthus–Coelodonta Faunal Complex)

Pleistocene Mammoth Faunas were the most successful, cold-adapted large mammal assemblages in the history of the Earth. However, the causes for their emergence can not be attributed only to the global trend of climate cooling which occurred during the Neogene/Quaternary period. The formation of the Eurasian Mammuthus–Coelodonta Faunal Complex was a result of interacting tectonic, geographical, climatic, ecological and phylogenetic processes. The key environmental factors controlling the origin and evolution of Palaearctic cold-adapted large mammal faunas were successive aridification of major parts of Eurasia, rhythmic global climatic cooling with prolonged and intensified cold stages, and increasing continentality.Between 2.6 Ma and around 700 ka BP, largely independent mammal faunas became established in continental Asian steppe regions as well as in the circumpolar tundra. Both faunal complexes were adapted to open environmental conditions but were largely separated from each other. The principal requirements in order for species to evolve into members of Mammoth Faunas are progressing adaptation to aridity, decreasing temperatures and rapid temperature fluctuations. Eurasian Mammoth Faunas were mainly composed of the descendants of either Central Asian steppe or Arctic tundra faunal elements. The majority of species of Central Asian origin emerged in regions north of the Himalayan–Tibetan uplift. Between 640 and 480 ka BP, saiga, musk-ox and reindeer occasionally spread far beyond the limits of their respective traditional areas, thus anticipating the subsequent merge of steppe and tundra originated species in Eurasian Mammoth Faunas.During the pronounced cold period of MIS 12, tundra species regularly expanded south- and southwestward into a newly formed type of biome, the so-called tundra-steppe. In parallel, species originating from the Asian steppe dispersed into new habitats north and northwest of their ancestral distribution areas. This drastic faunal turnover led to the formation of the earliest pan-Eurasian Mammoth Fauna at around 460 ka BP. The sister taxa of several species involved in Mammoth Faunas underwent separate evolution in Central Asia, thus indicating ecological differences between the Asian core steppe and Eurasian tundra-steppe habitats. During temperate and humid stages of the late Middle to Late Pleistocene periods the transcontinental reach of the steppe-tundra biome collapsed. As a result, the majority of the characteristic mammal species were forced back to continental steppe or Arctic tundra refugia, only returning during subsequent cold stages when the formation of a new and more evolved Mammoth Fauna began. The maximum geographic extension of the Palaearctic Mammuthus–Coelodonta Faunal Complex occurred during the Late Pleistocene, when it covered an area of up to 190 degrees of longitude and 40 degrees of latitude.

Petrogenesis and thermal history of the Yulong porphyry copper deposit, Eastern Tibet: insights from U-Pb and U-Th/He dating, and zircon Hf isotope and trace element analysis

The Yulong porphyry copper deposit (6.5 Mt at 0.46 % Cu) in eastern Tibet was formed in a post-collisional setting. New zircon U–Pb and U–Th/He ages, apatite U–Th/He ages and in-situ zircon Hf isotopic and trace element data for the Yulong ore-bearing adakitic porphyries elucidate the thermal history and petrogenesis of the deposit. Zircon U–Pb ages range from from 41.2 Ma to 40.7 Ma, indicating an Eocene formation age. Combined with the zircon U–Th/He age of 37.5 ± 1.2 Ma, results suggest that magmatic-hydrothermal evolution lasted up to 5 m.y. The apatite U–Th/He age of 33.4 ± 0.9 Ma reflects Yulong deposit exhumation during the ~33–30 Ma Tibetan uplift. Moreover, the high eHf(t)-values (7.1 ~ 12.2) zircon yield the highest ΣREE content, higher Y/Hf, lower Ce/Ce* and higher Th/U ratios compared to inherited zircon or magmatic zircon suggesting that the high eHf(t) zircon crystallized from another magma, and that magma mixing probably contributed to the adakitic porphyries at Yulong. In addition, inherited and magmatic zircon with the lowest eHf(t) values (−20.6 ~ −4.4) suggest crustal contamination. The positive zircon eHf(t) values indicate a source in the juvenile arc lower crust. Significantly, the juvenile arc lower crust inherited arc magma characteristics (abundant F, Cl, Cu and high oxidation state), which are now found in the porphyry Cu–Mo deposits.

Diets and environments of late Cenozoic mammals in the Qaidam Basin, Tibetan Plateau: Evidence from stable isotopes

The timing history and driving mechanisms of C4 expansion and Tibetan uplift are hotly debated issues. Paleoenvironmental evidence from within the Tibetan Plateau is essential to help resolve these issues. Here we report results of stable C and O isotope analyses of tooth enamel samples from a variety of late Cenozoic mammals, including deer, giraffe, horse, rhino, and elephant, from the Qaidam Basin in the northeastern Tibetan Plateau.The enamel-δ13C values are <−8‰ for modern samples and ≤–7‰ for fossils, except for one late Miocene rhino (CD0722, with δ13C values up to −4.1‰). If the Qaidam Basin was as arid as today in the Mio-Pliocene, these data would indicate that the majority of the animals had C3 diets and only a few individuals (besides the exceptional rhino CD0722) may have consumed some C4 plants. Based on geological evidence, however, the Qaidam Basin was probably warmer and more humid during the late Miocene and early Pliocene than today. Thus, these δ13C values likely indicate that many individuals had significant dietary intakes of C4 plants, and the Qaidam Basin had more C4 plants in the late Miocene and early Pliocene than today. Moreover, the Qaidam Basin likely had much denser vegetation at those times in order to support such large mammals as rhinos and elephants.While the δ18O values did not increase monotonously with time, the range of variation seems to have increased considerably since the early Pliocene, indicating increased aridification in the basin. The mean δ18O values of large mammals and those reconstructed for local meteoric waters display a significant negative shift in the late Miocene, consistent with the marine δ18O record which shows a cooling trend in the same period.Taken together, the isotope data suggest a warmer, wetter, and perhaps lower Qaidam Basin during the late Miocene and early Pliocene. Increased aridification after the early Pliocene is likely due to a combined effect of regional tectonism, which resulted in a more effective barrier preventing moisture from the Indian Ocean or Bay of Bengal from reaching the basin, and global cooling.

Geochemical studies on the source region of Asian dust

The North China and the neighbouring Mongolia in Asian Interior is characterized by extremely dry climate, resulted in one of the world’s major dust emission centres. Deciphering the source region of Asian dust is critical for revealing the mechanism of the dust production, interpreting the paleo-environmental records of eolian deposits, predicting the overall environmental effects of dust, and setting the strategies for the control of contemporary dust storms. This paper summarizes the geochemical methods applied to the source tracing of Asian dust. Nd-Sr isotopes were the most extensively studied source tracer of Asian dust and have been successfully applied in many cases. Geochemistry of detrital monomineral shows great theoretical advantages in source tracing and deserves further studies. The short-range transportation of Chinese loess with direction similar to that of the prevailing near surface wind is revealed. Source tracing also shows that the Asian dust has two ultimate material sources from the northern margin of the Tibetan Plateau and the Central Asian Orogen, which confirms the importance of mountain processes in the production of silt eolian particles. Based on the recent progresses on the source tracing of Asian dust, discussions are expanded on the natural background of Asian dust storms and potential anthropogenic influence, the materials evolution of the source regions of Asian dust and its relationships with climate changes and Tibetan uplift, and the role of Tibetan uplift in the Asian dust system.

Northern Tibetan Plateau cooling and aridification linked to Cenozoic global cooling: Evidence from n-alkane distributions of Paleogene sedimentary sequences in the Xining Basin

The Xining Basin on the northeastern Tibetan Plateau holds the longest continuous Cenozoic stratigraphic record in China. The sequence record contains considerable information on the history of Tibetan uplift and associated climatic change. In particular, high resolution n-alkane biomarker proxy and pollen records have been obtained from the Paleogene sediments of the Xiejia section of the basin. A combination of the n-alkane and palynological records reveals that the paleoclimate in the Xining Basin experienced a long-term cooling trend from 50.2 to 28.2 Ma with a distinctive ecological event spanning 37.5 to 32.7 Ma. Since this ecological event, a vertical zonation of vegetation from lowland arid grasses, to middle-elevation subtropical broad-leaf plants, to high-elevation coniferous trees was established. We interpret that these changes in climate and vegetation were probably responses to a combination of long term global cooling since the Eocene climatic optimum and uplift of the surrounding mountains on the northern Tibetan Plateau in the early Cenozoic.

Increasing Nd isotopic ratio of Asian dust indicates progressive uplift of the north Tibetan Plateau since the middle Miocene

Research Article| March 01, 2011 Increasing Nd isotopic ratio of Asian dust indicates progressive uplift of the north Tibetan Plateau since the middle Miocene Gaojun Li; Gaojun Li * 1State Laboratory of Mineral Deposits Research, Institute of Surficial Geochemistry, Department of Earth Sciences, Nanjing University, Nanjing 210093, China2Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK *E-mail: ligaojun@nju.edu.cn; chenjun@nju.edu.cn. Search for other works by this author on: GSW Google Scholar Thomas Pettke; Thomas Pettke 3Institute of Geological Sciences, University of Bern, Baltzerstrasse 1+3, CH-3012 Bern, Switzerland Search for other works by this author on: GSW Google Scholar Jun Chen Jun Chen * 1State Laboratory of Mineral Deposits Research, Institute of Surficial Geochemistry, Department of Earth Sciences, Nanjing University, Nanjing 210093, China *E-mail: ligaojun@nju.edu.cn; chenjun@nju.edu.cn. Search for other works by this author on: GSW Google Scholar Author and Article Information Gaojun Li * 1State Laboratory of Mineral Deposits Research, Institute of Surficial Geochemistry, Department of Earth Sciences, Nanjing University, Nanjing 210093, China2Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK Thomas Pettke 3Institute of Geological Sciences, University of Bern, Baltzerstrasse 1+3, CH-3012 Bern, Switzerland Jun Chen * 1State Laboratory of Mineral Deposits Research, Institute of Surficial Geochemistry, Department of Earth Sciences, Nanjing University, Nanjing 210093, China *E-mail: ligaojun@nju.edu.cn; chenjun@nju.edu.cn. Publisher: Geological Society of America Received: 08 Sep 2010 Revision Received: 29 Sep 2010 Accepted: 05 Oct 2010 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2011 Geological Society of America Geology (2011) 39 (3): 199–202. https://doi.org/10.1130/G31734.1 Article history Received: 08 Sep 2010 Revision Received: 29 Sep 2010 Accepted: 05 Oct 2010 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Gaojun Li, Thomas Pettke, Jun Chen; Increasing Nd isotopic ratio of Asian dust indicates progressive uplift of the north Tibetan Plateau since the middle Miocene. Geology 2011;; 39 (3): 199–202. doi: https://doi.org/10.1130/G31734.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The time and rate of Tibetan uplift is critical in understanding both the geodynamics of plateau growth and the influence of mountain building on climate change. Models predict that the uplift of the north Tibetan Plateau (NTP) occurred later than uplift of the south and central Tibetan Plateau; uplift of the NTP is believed to have initiated the aridity in the interior of Asia, and to have critically affected the evolution of Asian monsoon and, ultimately, global climate. The history of NTP uplift has remained uncertain, however; scenarios range from Early Miocene to the past million years. This work provides new evidence by relating the Nd isotopic evolution of Asian dust to NTP uplift. The sources of the Asian dust are located in the arid lands between the NTP and the Central Asia orogen. Mass balance calculations indicate that the decreasing εNd values, from −8.2 to −10.4 for Pacific dust since 15 Ma, reflects increasing relative contribution of NTP materials (40% to 70%) to the dust source. As paleoelevation in the Central Asia orogen has largely remained constant, the increasing relative NTP detritus contribution is interpreted to reflect the progressive surface uplift of the NTP at a rate of at least 0.12 mm yr−1 since 15 Ma. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Reconciling plate kinematic and seismic estimates of lithospheric convergence in the central Indian Ocean

The far-field signature of the India-Asia collision and history of uplift in Tibet are recorded by sediment input into the Indian Ocean and the strain accumulation history across the diffuse plate boundary between the Indian and Capricorn plates. We describe the history of India-Capricorn convergence from updated estimates of India-Somalia-Capricorn plate rotations and observations derived from seismic reflection data. New India-Capricorn plate rotations for the past 20 m.y. are consistent with slow north-south convergence from 18 Ma about a stationary or nearly stationary pole near the eastern edge of the Chagos-Laccadive ridge, simpler than predicted by previous models based on many fewer data. The new rotations suggest that convergence began between 18 and 14 Ma, consistent with marine seismic evidence for an onset of deformation at 15.4–13.9 Ma. They further show that convergence rates doubled at 8 Ma, in agreement with a sharp increase in fault activity at 8–7.5 Ma seen on seismic reflection profiles. A discrepancy between the total strain estimated from kinematic and seismic reflection data can be reconciled if pervasive reverse faulting within the diffuse plate boundary is accompanied by block rotations of 1°–3°.

Pinus prekesiya sp. nov. from the upper Miocene of Yunnan, southwestern China and its biogeographical implications

Pinus prekesiya Xing, Liu et Zhou sp. nov. was described as a new species on the basis of two well preserved ovulate cones from the upper Miocene of central Yunnan, southwestern China. It is the first fossil record of three dimensionally preserved Pinus ovulate cones from China. Morphological comparisons with 15 previously published Cenozoic cones and seven related extant pine species reveal that the fossil cones are identified as a new species, P. prekesiya sp. nov., which belongs to subsection Pinus of subgenus Pinus. The new species shows a combination of characters of P. kesiya and P. yunnanensis, but has a closer affinity with P. kesiya which occurs in the humid region of Yunnan and therefore suggests a more humid climate in central Yunnan during the late Miocene than today. The general cooling trend during the late Neogene and topographic change due to the dramatic Tibetan uplift might have caused a vicariant origin of P. kesiya and P. yunnanensis from the ancestral P. prekesiya.

Aeolian sediment evidence that global cooling has driven late Cenozoic stepwise aridification in central Asia

Abstract It has been a long held view that uplift of the Tibetan Plateau dominated stepwise climatic drying in central Asia during the late Cenozoic. On the other hand, global cooling may also have forced Asian drying and the subsequent formation of aeolian deposits in north China. Until now, whether the Tibetan uplift or the global cooling has been the first-order driver controlling stepwise Asian drying has remained a contentious issue. In this study, we examine the thick aeolian silt deposit, which is regarded as a good archive of palaeoclimatic changes in central Asia and north China, in order to qualitatively reconstruct the drying process in Asia during the late Cenozoic. On the basis of our long-term field surveys, laboratory analyses and previous investigations, we have obtained time sequences of Asian drying from the early Miocene to late Pleistocene; we compare this newly reconstructed time series of Asian aridification with the time series of global cooling and Tibetan uplift to identify the first-order driver of stepwise Asian aridification. A good match between the drying and global cooling might indicate that global cooling was the most likely driver of stepwise drying in interior Asia. On the other hand, controversy regarding timing and amplitude of Tibetan uplift during the late Cenozoic suggests that the prevailing conclusion that Tibetan uplift forces Asian drying should be regarded as immature. A mechanism that global cooling drove the Asian drying is tentatively suggested.

The impacts of Tibetan uplift on palaeoclimate proxies

Abstract Several palaeoclimate proxy records have been interpreted as representing the direct effects of Tibetan uplift on climate, and particularly the intensity of the Asian summer monsoon. However, there are other possible causes for the transitions and changes which have been observed, such as varying greenhouse gas concentrations, nodes or extremes in orbital forcing, and changing continental configurations. In this study we model the direct effects of Tibetan uplift on sea surface temperatures (SSTs), vegetation, and river discharge. We investigate whether these climatic effects of topographic uplift are likely to be detectable in proxy records, and also whether the proxies could be used to distinguish between different paradigms for the history of plateau uplift. We find that the SSTs in the western Pacific, South China Sea and Indian Ocean are generally insensitive to Tibetan uplift; however, vegetation in the region of the plateau itself, and river discharge from the Yangtze, Pearl, and in particular the Ganges/Brahmaputra, could provide a good test of our understanding of Tibetan uplift history.

Multiple in-to-Africa dispersals of labeonin fishes (Teleostei: Cyprinidae) revealed by molecular phylogenetic analysis

An out-of-Africa dispersal route has been proposed for many organisms, including modern man. However, counter examples of in-to-Africa dispersal routes are less common. In the present article, the phylogenetic relationships within the Labeoninae, a subfamily of cyprinid fishes distributed in Asia and Africa, were analyzed to investigate the biogeographic processes governing the modern distribution of these Asian and African cyprinids. The mitochondrial DNA cytochrome b gene was used as a molecular marker. The phylogenetic analysis indicated that the subfamily Labeoninae is a monophyletic group, with some Asian labeonins located at the basal position. Two subclades were found that contained both African and Asian species, which highlighted a need for further biogeographic analysis. Based on this analysis, it is proposed that the centre of origin of the Labeoninae was in East Asia. Molecular clock estimation suggests that the Labeoninae arose by the Early Miocene (~23 MYA) during the period of the second Tibetan uplift. Subsequently, two dispersal events of labeonins from Asia into Africa occured in the Early Miocene (~ 20 MYA) and Late Miocene (~9 MYA) and serve as examples counter to out-of-Africa dispersal.

Significant mid-latitude aridity in the middle Miocene of East Asia

The East Asian climate history during the Neogene is a complicated and contentious issue, in particular because of its bearing on the development of the East Asian monsoon and Tibetan uplift chronology. Here we present a paleoprecipitation analysis based on mean molar tooth height (hypsodonty) of large herbivorous mammals to investigate the spatial pattern of climate zonation in East Asia during the middle Miocene. We show a generally humid and uniform situation before the late middle Miocene, replaced by a mid-latitude arid belt from the late middle Miocene, into the earlier part of the late Miocene. These findings are concordant with the global phenomena of the middle Miocene climate optimum and the subsequent cooling, and suggest that the predominant climate in East Asia for most of the Miocene was planetary rather than monsoonal. Our results support a late initiation of the East Asian summer monsoon, coincidentally with the beginning of eolian red clay deposition in the later late Miocene at 7–8 Ma.

Baiyun movement: A significant tectonic event on Oligocene/Miocene boundary in the northern South China Sea and its regional implications

A significant geologic event occurred on the Oligocene/Miocene boundary at 23.8 Ma in the northern South China Sea, which is named the Baiyun (白云) movement in this article. This event strongly affected not only the South China Sea, but also East Asia. After the Baiyun event, the ridge of seafloor spreading of the South China Sea jumped southward and rotated counterclockwise, and a strong subsidence occurred in the Baiyun sag of the Pearl River Mouth basin. The shelf break shifted suddenly from the south to the north of the Baiyun sag, and the deposition environment in this sag changed from continental shelf with neritic deposition to continental slope with deep-water deposition. Sediment geochemistry study indicated that the Baiyun event played a key role in the rapid change of sediment provenance for the Pearl River Mouth basin. Between 32 and 23.8 Ma, the source of sediments was mainly from the granites in South China, while after 23.8 Ma some sediments might have come from the eastern Himalaya, as the Pearl River drainage extended westward after the uplift of Tibet since that time. The Baiyun event led to a great change in the drainage framework of the paleo-Pearl River, sediment types and the depositional environments in the Pearl River Mouth basin, and relative sea level of the northern South China Sea, as well as sedimentation and hydrocarbon accumulation in the area.

The earliest immigration of woolly rhinoceros ( Coelodonta tologoijensis, Rhinocerotidae, Mammalia) into Europe and its adaptive evolution in Palaearctic cold stage mammal faunas

The cold adapted larger mammal faunas of Pleistocene Eurasia (the so-called Mammuthus– Coelodonta faunas) were mainly composed of autochthonous Palaearctic elements. Whereas the history of the immigration and evolution of European woolly mammoths has been exhaustively studied, comparable investigations for woolly rhinoceroses are lacking. Referring to the remains of European and Asian Coelodonta in general and the first skull to be found of a European woolly rhinoceros of early Middle Pleistocene age (from Bad Frankenhausen, Germany) in particular, the occurrence, dispersal, morphological evolution and ecological adaptation of early Coelodonta are reviewed. Coelodonta originated around 2.5 Myr BP north of the Himalayan–Tibetan uplift. The genus was restricted in its range to different types of steppe landscapes of continental Asia for more than two million years and it wasn't until MIS 12, when extended phases of low temperature and aridity prevailed in western Eurasia that woolly rhinoceroses comparable to Coelodonta tologoijensis spread westward towards Central Europe for the first time. Coelodonta entered Central and, in several cases, Western Europe during all of the subsequent Middle to Late Pleistocene cold stages. Morphological evolution, in particular, the elongation and narrowing of the head and successively its lower and more inclined posture, the shift of the orbits towards the rear of the skull, and changes in the position and morphology of the tooth row concurrently indicate progressive adaptations to an efficient grazer. During the course of their Plio-/Pleistocene evolution, Coelodonta rhinoceroses changed strikingly from cursorial mixed feeders of central Asian origin to graviportal, highly specialised grazers, inhabiting huge belts of tundra–steppe-like environments during dry and cool to cold periods, and thus becoming the only rhinocerotid to join the Eurasian mammoth faunas. The Bad Frankenhausen Coelodonta record dates the initial formation of a pan-Eurasian Mammuthus– Coelodonta faunal complex to about 460 kyr BP.

Tibetan uplift intensified the 400 k.y. signal in paleoclimate records at 4 Ma

Knowledge of when and how a specific climatic threshold is crossed is one key to an understanding of the evolution of Earth's climate system. We have observed a simultaneous intensification of the similar to 400 k.y. cycle, in both proxy records for global ice volume and for East Asian monsoon precipitation on the Chinese Loess Plateau at ca. 4 Ma, indicating that important climatic thresholds were crossed. The 400 k.y. climatic cycles can be substantially intensified by clipped responses to insolation. We argue that Tibetan uplift accelerated at ca. 4 Ma and triggered such responses. The weaker orbital-band climatic signal during the interval 4-3.6 Ma indicates that the thresholds were only crossed slightly.

A major reorganization of Asian climate by the early Miocene

Abstract. The global climate system experienced a series of drastic changes during the Cenozoic. In Asia, these include the climate transformation from a zonal pattern to a monsoon-dominated pattern, the disappearance of typical subtropical aridity, and the onset of inland deserts. Despite major advances in the last two decades in characterizing and understanding these climate phenomena, disagreements persist relative to the timing, behaviors and underlying causes. This paper addresses these issues mainly based on two lines of evidence. First, we compiled newly collected data from geological indicators of the Cenozoic environment in China as paleoenvironmental maps of ten intervals. In confirming the earlier observation that a zonal climate pattern was transformed into a monsoonal one, the maps within the Miocene indicate that this change was achieved by the early Miocene, roughly consistent with the onset of loess deposition in China. Although a monsoon-like regime would have existed in the Eocene, it was restricted to tropical-subtropical regions. The latitudinal oscillations of the climate zones during the Paleogene are likely attributable to the imbalance in evolution of polar ice-sheets between the two hemispheres. Secondly, we examine the relevant depositional and soil forming processes of the Miocene loess-soil sequences to determine the circulation characteristics with emphasis on the early Miocene. Continuous eolian deposition in the middle reaches of the Yellow River since the early Miocene firmly indicates the formation of inland deserts, which have been constantly maintained during the past 22 Ma. Grain-size gradients between loess sections indicate northerly dust-carrying winds from northern sources, a clear indication of an Asian winter monsoon system. Meanwhile, well-developed Luvisols show evidence that moisture from the oceans reached northern China. This evidence shows the coexistence of two kinds of circulations, one from the ocean carrying moisture and another from the inland deserts transporting dust. The formation of the early Miocene paleosols resulted from interactive soil forming and dust deposition processes in these two seasonally alternating monsoonal circulations. The much stronger development of the early Miocene soils compared to those in the Quaternary loess indicates that summer monsoons were either significantly stronger, more persistent through the year, or both. These lines of evidence indicate a joint change in circulation and inland aridity by the early Miocene and suggest a dynamic linkage of them. Our recent sensitivity tests with a general circulation model, along with relevant geological data, suggest that the onset of these contrasting wet/dry responses, as well as the change from the "planetary" subtropical aridity pattern to the "inland" aridity pattern, resulted from the combined effects of Tibetan uplift and withdrawal of the Paratethys seaway in central Asia, as suggested by earlier experiments. The spreading of South China Sea also helped to enhance the south-north contrast of humidity. The Miocene loess record provides a vital insight that these tectonic factors had evolved by the early Miocene to a threshold sufficient to cause this major climate reorganization in Asia.

Timing and processes of Himalayan and Tibetan uplift

Timing and processes of Himalayan and Tibetan uplift