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The Xining basin is located in the northeastern margin of the Qinghai‐Tibet Plateau. It is a rift basin formed in Mesozoic and Cenozoic and structurally belongs to the intersection of Kunlun and Qilian Mountains. Cenozoic fluvial and lacustrine sedimentary strata are continuous in the Xining basin, with a thickness of more than 800 m, completely recording the deformation uplifting, weathering and denudation history and climate change process of the northeastern plateau. Currently, early Miocene Xijia fauna, early Middle Miocene Danshuilu fauna and late Middle Miocene Diaogou fauna are discovered in the Xining basin, which provide an important basis for the stratigraphic correlation of the Cenozoic strata in the Xining basin. However, in the next few decades, there are no reports about the large mammal fossils in the Xining basin, especially about late Miocene fauna. The author discovered a large amount of mammal fossils in the Neogene sedimentary strata in Huzhu area, Xining basin. According to the identification results of the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, these fossils mainly included Hipparion dongxiangense, Chilotherium sp., Parelasmotherium sp., Stephanocemas sp. and Kubanochoerus sp. and their age was early Late Miocene. Since the discovery of this set of fossils directly filled the blank that there were no large mammal fossils in the Xining basin in Late Miocene, it was very important for studying the magnetic stratigraphic chronology of fossil‐forming strata and establishing the paleomagnetic chronology scale plate of mammal fossils. In this paper, the paleomagnetic data of the fossil‐forming stratigraphic profile, Banyan profile, were measured and the paleomagnetic records were collected through high density sampling, and finally the paleomagnetic polarity column of the profile was established. The results showed that five positive and five negative polarity segments were recorded in Banyan profile, which corresponded well to the polarity between C3Br.1n‐C4n.2n in the standard polarity column. The age of profile top was about 7.25 Ma and profile bottom was about 8.4 Ma, with an age range of 1.15 Ma. The mammal fossils discovered this time were exposed between positive and negative polarities N5 and R5 at the bottom of the profile, corresponding to C4r.1r at negative polarity and C4n.2n at positive polarity in the standard polarity column. The age of mammal fossils was about 8.3 Ma. The paleomagnetic chronology of the strata and paleontological fossils determined the absolute age of late Miocene mammal fossils and expanded the upper age of late Miocene Xianshuihe Formation (N1xn) in the Xining basin, which had provided new basic data for further studying the stratigraphic deposition and correlation of late Cenozoic strata and regional environmental evolution. [ABSTRACT FROM AUTHOR]

Abstract: The Pliocene (5.3–2.6Ma) of Tibet witnessed the drying of the northern Tibetan Plateau and the approach to the Pleistocene Ice Age within the background of intensifying Indian and East Asian monsoons. Yet little is known about Pliocene mammals living on the high Tibetan Plateau despite the fact that fossil mammals elsewhere constitute an important knowledge base for terrestrial environments. The late Miocene to Pleistocene Zanda Basin at the northern foothills of the Himalayas affords a welcome opportunity to evaluate the biological response to environmental change at high elevations. Abundant, well-preserved fossil mammals and fish from an 800-m continuous section of fine- to coarse-grained sediments thus open a rare window into a past biological world. For example, the discovery of an ancestral wooly rhino from Zanda Basin that was the precursor of its late Pleistocene megafaunal descendants leads to our “out-of Tibet” hypothesis, suggesting that the high Tibetan Plateau was a Pliocene cradle for Ice Age cold adaptations. In this paper, we document in detail the mammalian biostratigraphy, chronology, and paleozoogeography based on Zanda Basin fossil mammals. Our high-resolution biostratigraphy and biochronology offer for the first time independent constraints that both support and modify recent magnetostratigraphic correlations. Using characteristic Pliocene and Pleistocene mammals, particularly the small mammal assemblages in the lower part of the section and monodactylid Equus from the upper section, we propose a correlation to C1n to C3An.1r, with an age range of ~400Ka to 6.4Ma. Within the 800-m Zanda section, the lower 0–150m is of latest Miocene age, spanning 6.4–5.3Ma. Sparsely fossiliferous, the lower section has produced five taxa so far: Ochotona, Panthera, Qurliqnoria, Palaeotragus, and Hipparion—all are consistent with a late Miocene age. The middle 150–620m section spans the entire Pliocene. This section is by far the most fossiliferous, including such typical Pliocene small mammals as Prosiphneus, Mimomys, Apodemus, and Trischizolagus, as well as large mammals such as Coelodonta thibetana, Hipparion zandaense, Chasmaporthetes, Nyctereutes, Meles, Antilospira, and others. In the upper 620–800m section the fossils are rare, but do include characteristic Pleistocene taxa such as Equus. Zoogeographically Zanda Basin mammals are a mixture from two major sources. Taxa such as Mimomys, Prosiphneus, Trischizolagus, Chasmaporthetes, Nyctereutes, Meles, and Xenocyon are commonly found in north China or east Asia. In contrast, several forms, such as unique species of pikas (Ochotona), squirrels (Aepyosciurus), and ancestral Tibetan antelope (Qurliqnoria), seem to belong to an indigenous Tibetan fauna evolved within the plateau. A lack of shared taxa with the Oriental Realm suggests a formidable barrier by the Himalayas despite a short distance (~100km) between Zanda Basin and the Indian subcontinent. [Copyright &y& Elsevier]

Abstract: This paper presents detailed SHRIMP zircon U–Pb chronology, mineral chemistry, major and trace element, and Sr–Nd–Hf isotope geochemistry of two Cenozoic plutons (Karibasheng and Kuzigan) in western Tibetan Plateau, China. The Karibasheng pluton is composed of monzogranite, and the Kuzigan pluton consists of syenogranite, diopside-bearing syenite and diopside syenite. SHRIMP zircon U–Pb dating on monzogranite, syenogranite and diopside syenite shows that they were emplaced in Miocene (12–10Ma). These rocks are metaluminous and show the affinities with shoshonitic rocks, i.e., alkali-rich (K2O+Na2O=8.6–13.4wt.%), high K2O contents (4.7–10.6wt.%) with high K2O/Na2O ratios (1.2–4.6), enrichment in large ion lithophile elements (LILE) (e.g., Ba=2200–9100ppm; Sr=840–3100ppm, most >1100ppm) and rare earth elements (REE), especially light REE (LREE) (La/Yb up to 168). The rocks are depleted in high field strength elements (HFSE) but show high Nb/Ta ratios (13.3–30.7). The granites have lower initial 87Sr/86Sr ratios (0.7091–0.7099) and higher εNd (T) values (−7.1 to −9.5) than the syenites that have initial 87Sr/86Sr ratios of 0.7095–0.7117 and εNd (T) values of −8.6 to −12.2. Their zircon εHf (T) values (−7.2 to −9.7) are coupled with their whole-rock εNd (T) values, and plot along the mantle array. The amphibole–plagioclase thermometer and estimation of apatite saturation temperature indicate that the primary magmas had high temperatures (up to 880°C for the granites and up to 1100°C for the syenites). The source depth for the granites and syenites is <70–100km inferred by the metasomatic volatile phase (amphibole–phlogopite) relation, and thus most probably within the upper part of lithospheric mantle. Detailed elemental and isotopic data and major element modeling suggest that the granites and syenites were derived directly by partial melting of the veined lithospheric mantle that had been hybridized by the continental slab-derived melts. Continental slab break-off was most likely the mechanism associated with the generation of these granites and syenites. [Copyright &y& Elsevier]

There is a cross-cutting relationship between the E-W trending structures and the NE-trending structures in the northern Longmen-Micang Mountains region, which reflects possible regional tectonic transition and migration. Apatite fission track (AFT) analyses of 15 samples collected from this area yield apparent ages varying from 30.3±4.2 Ma to 111.7±9.0 Ma and confined-track-lengths ranging from 10.6±0.3 μm to 12.4±0.1 μm. Four specific groups were identified on the basis of the Track Age Spectrum Calculation (TASC) patterns, i.e., 143-112 Ma, 93.6-88 Ma, 42-40 Ma and ∼25.6 Ma. These age groups correspond to the spatial distributions of datasets and may represent four tectonic events. Together with the regional deformation patterns, the four age groups are interpreted to indicate tectonic superposition, transition and migration during the Meso-Cenozoic with the following possible order: (1) the Micang Mountains belt was dominated by the E-W trending structure during 143-112 Ma; (2) the contraction of the Longmen Mountains belt from the NW to the SE during 93.6-88 Ma led to the superposition of the NE-trending structures over the E-W trendinding structures; (3) dextral strike-slip shear dominated the Longmen Mountains belt at 42-40 Ma; (4) westward migration of the active tectonic belt occurred from 93.6-25.6 Ma in a break-back sequence in the northern Longmen Mountains belt. The Late Cenozoic tectonics in the northern Longmen Mountains belt are characterized by the dextral strike-slip shear and the occurrence of westward break-back sequence of deformations. As a result, north-south differences in deformations along the Longmen Mountains belt were intensified since the Miocene time and strains were mainly accumulated in the hinterland of the Longmen Mountains instead of being propagated to the foreland basin. [ABSTRACT FROM AUTHOR]

Abstract: Based on field mapping, section measurement and magnetostratigraphy, ∼1700m of sedimentary rocks have accumulated in the Wushan basin between ∼16Ma and ∼6Ma. Basin geometry, sedimentation characteristics and the early syn-depositional deformation along the northern margin of the basin indicate that formation of the Wushan basin was related to tectonic deformation along the West Qinling fault zone during the middle Miocene. A series of basins of similar age to the Wushan basin were generated along and to the south of the West Qinling fault zone while basalts also erupted in this region at this time. We suggest that the middle Miocene (∼16Ma) may represent a change in kinematics and deformation style in the region along and to the south of the West Qinling fault zone. At this time, there was a transition from NNE–SSW compressional deformation, that dominated the region since the late Paleogene, to the development of WNW–ESE and/or E–W trending strike-slip movement and associated transpressional and transtensional activity that continues today. The Miocene Wushan basin may have developed in association with transpression along the West Qinling fault zone. Whether this transition was related to the onset of strike-slip along the east Kunlun fault and related deformation transfer, lower crustal flow, or removal of mantle lithosphere, the middle Miocene provides direct evidence for a change in the kinematic style along the plateau margin. [Copyright &y& Elsevier]

The central inversion zone in the Xihu Depression, East China Sea, was formed during the Late Miocene. The entire Tertiary succession, nearly 10,000 m thick, has undergone inversion here. The succession is composed mainly of sandstones and mudstones with minor coals and non-marine limestones. Hydrocarbons are present in a series of structural traps which formed as a result of inversion-related deformation. Oil and gas exploration in the Xihu Depressions has demonstrated that at least 90% of the commercial reserves so far found occur in inversion-related structural traps in the central inversion zone, mainly in Eocene (Pinghu Formation) and Oligocene (Huagang Formation) sandstone reservoirs. Previous studies have shown that structural traps are controlled by the intensity and style of inversion tectonics. However, the relationship between the geometry, kinematics and size of the inversion structures and the oil and gas accumulations is not well understood. In this paper, the factors controlling trap formation (and hydrocarbon acumulations) in the study area are considered. Data came from 2D reflection seismic and electic logs from a number of wells. Controlling factors include inversion fault activity rate, inversion rate and the thickness of sediments eroded as a result of inversion-related uplift of the Tertiary succession. The results show that the best exploration targets are located in the southern part of the central inversion zone. This area has a relatively low inversion fault activity rate (average 3.0 m/Ma) and a low inversion rate (average 0.4); a relatively small thickness of sediments was eroded from the Miocene Longjing and Liulang Formations (< 400 m) and the Eocene Pinghu Formation. By contrast, the northern part of the central inversion zone has a relatively high inversion fault activity rate (average 6.8 m/Ma) and a high inversion rate (0.8), and greater thicknesses of sediments were erosively removed (up to 1600 m). This may have resulted in the less favourable preservation of traps and the large-scale leakage of oil and gas. Most oil and gas accumulations occur in the southern part of the central inversion zone, especially in reservoirs in the Longjing, Liulang and Pinghu Formations. [ABSTRACT FROM AUTHOR]

Abstract: Porphyry Cu–Mo deposits, related to the Miocene adakitic porphyries from the Gangdese porphyry copper belt in the southern Tibet, formed in a post-collisional setting. Here, we present the new zircon U–Pb ages, whole-rock chemical, and Sr–Nd and zircon Hf isotopic data for the ore-bearing adakitic porphyries from Gangdese porphyry copper belt. LA-ICP-MS zircon dating for six samples yielded ages ranging from 19Ma to 14Ma, indicating they formed in the Miocene. The ore-bearing adakitic porphyries show SiO2 of 61.47–71.67%, K2O of 3.29–4.74%, and high Sr content (394–1106ppm), high Sr/Y ratios (63–158), and low Y (6.12–10.3ppm) and heavy rare earth element contents (e.g. Yb=0.52–0.91ppm). They show steep fractionated REE and flat HREE patterns, and strong enrichment in large ion lithophile elements (Cs, Rb, Ba, Th, and U) and depletion of high field strength elements (Nb), with positive Sr and negative Ti anomalies. There are no linear variations of Ba, La, Sr/Y, Dy/Yb, (87Sr/86Sr)i, and εNd(t) with increasing SiO2 content. Combined with the zircon positive εHf(t) values, and wide range of (87Sr/86Sr)i (0.70559 to 0.70908) and of εNd(t) (−6.8 to 0) values for all the adakitic samples, they were likely derived from the melting of garnet-bearing amphibolite in the juvenile arc mafic lower crust. Additionally, the adakitic porphyries with low Th/Nb ratios have lower initial 87Sr/86Sr, and higher εNd(t) and εHf(t) values, and those with high Th/Nb show higher initial 87Sr/86Sr, and lower εNd(t) and εHf(t) values. This indicates that the juvenile arc lower crust is derived from the melting of the mantle wedge that was metasomatized by slab fluid or sediment melt during the Neotethyan ocean subduction. Significantly, the juvenile arc lower crust possibly inherited the arc magma characteristics of abundant in F, Cl, and Cu and high oxidation state, which contributed to the porphyry Cu–Mo deposits in the Gangdese porphyry copper belt. [Copyright &y& Elsevier]

Uplift of the Tibetan Plateau and its influence on our global climate have been the focus of numerous studies. Miocene potassic to ultrapotassic volcanism is widespread in southern Tibet and has been generally attributed to convective removal of collision-thickened Asian lithosphere, which is also responsible for the uplift of the plateau. An implicit assumption of this model is the existence of a hydrous, metasomatized (i.e., phlogopite bearing) lithospheric mantle that remained after the convective thinning and was subsequently heated to form small-volume melts. If such a lithospheric mantle was present in the Miocene, it implies further change since that time, as seismic velocities indicate that cold and strong upper mantle occurs beneath the thick crust in southern Tibet. Here we describe peridotite xenoliths entrained in Middle Miocene ultrapotassic lavas from Sailipu, southern Tibet. The results suggest the existence of hot, highly metasomatized lithospheric mantle beneath southern Tibet during the Middle Miocene, and thus support the idea that convective thinning of the lithosphere was responsible for the uplift of the plateau. The relict mantle was later removed or squeezed northward by the underthrusting Indian continental lithosphere, which terminated magmatism in southern Tibet and played a role in creating the entire plateau. [ABSTRACT FROM AUTHOR]

Abstract: 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 Oligocene, suggesting that these specimens could be of intermediate form between Eucricetodon and Cricetodon. One tooth of Eumyarion sp. was found, making its determination uncertain, but its morphology is clearly differentiated from the one of Cricetodon sp. The species K. debruijni nov. sp. is established based on its primitive features compared to the species known in Europe and Anatolia, and its specific association of characters compared to Karydomys dzerzhinskii. M. beijiangensis nov. sp. shows many plesiomorphic features compared to the species already described in the middle Miocene of China. Based on both the whole assemblage of rodents and the species of cricetids, the biochronologic position and the age of the locality are discussed. The locality appears to be biochronologically very close to the fauna from the Chul’adyr Formation in Aktau Mountains, but we propose an age slightly older than the one proposed for this fauna, probably equivalent to the MN3 biozone in Europe. [Copyright &y& Elsevier]

Abstract: The early middle Miocene biota from the Shanwang locality in eastern China is one of the most diverse and well preserved in the world. This overall richness contrasts with its low diversity of anuran amphibians. The most abundant anurans are representatives of the family Ranidae, which remains the dominant group in the extant anuran fauna of China. Besides Rana basaltica Young, some other ranids can be recognised at the locality, and are clearly distinguishable from R. basaltica based on their larger size and different proportions. Ranids are also represented by a developmental series of tadpoles, ranging from approximately Nieuwkoop-Faber (NF) stage 43 to a metamorphosing tadpole of NF stage 57. This is the first known developmental series of fossil non-pipoid Anura outside the Pelobatidae. In addition to the ranids, Bufo shandongensis nov. sp. (replacement name for B. linquensis), represented by one of the earliest known articulated bufonid skeletons, is described and illustrated. Another large toad, Macropelobates linquensis (Yang) nov. comb., is re-described; it can be assigned to the Pelobatoidea, with a possible relationship to the Scaphiopodidae, and can be considered, based on the presence of a large spade, a tibiofibula shorter than the femur, and a short astragalus and calcaneus, to be the earliest known anuran burrower. [Copyright &y& Elsevier]

East Tibet preserves broad areas of low relief that occur at elevations >3000 m and are dissected by major strike-slip faults that have been repeatedly reactivated since the late Mesozoic. Apatite fission-track samples from these low-relief, high-elevation surfaces indicate Cretaceous cooling (ca. 90 Ma). Fast rock uplift of the 110 °C isotherm and a fossilized partial annealing zone began in the plateau interior of east Tibet in the Miocene. Low denudation rates in the plateau interior during the Cenozoic, which are constrained by thermal history modeling and a consistency in ages from apatite fission tracks, suggest that dip-slip displacement on faults has been minor. Some localized areas have experienced the effects of structurally enhanced rock uplift and denudation or fault-related hydrothermal reheating. Cooling ages in Eocene sediments deposited on the older plateau surface suggest that rapid denudation occurred from the Miocene to Holocene. Other evidence of significant Ceno zoic denudation comes from river valleys, in particular, the Yalong River valley, where incision was initiated in the Oligocene to Miocene (28--12 Ma). Estimated mean denudation in east Tibet during the Cenozoic was ~1--2 km in the low-relief, high-elevation plateau interior and at least 5 km at the highrelief plateau margin in the Longmen Shan. The region south of the Longmen Shan and the Sichuan Basin was not uplifted with the main Tibetan Plateau in the Miocene, but it has undergone enhanced denudation since the Eocene. Due to an orographic effect, most of the denudation in the east Tibetan Plateau interior has occurred in major river valleys. Incision in the major rivers of the Longman Shan occurred simultaneously and has kept pace with surface uplift that began in the middle--late Miocene (12 Ma), with acceleration of denudation rates in the late Miocene (>5 Ma). [ABSTRACT FROM AUTHOR]

Here we report the first discovery of a relatively complete skull of Choerolophodon from the late early Miocene Dalanggou quarry of Linxia Basin, Gansu Province in China. The skull is low and elongated, with two enamel-less and outward-and-upward curved incisors and the choerolophodont molars. These characters indicate that the new specimen can be assigned to the genus Choerolophodon, as it is quite distinct from other common gomphotheres in northern China such as Gomphotherium, Platybelodon, and Sinomastodon. The skull is also primitive in possessing laterally-expanded zygomatic arches, anteriorly-positioned orbits, weakly-developed cheek teeth cement, and retention of a P4. Prior to this discovery, Choerolophodon was found primarily from the middle-late Miocene of Africa, Eastern Europe, and western and southern Asia. The discovery of this new material expands the known temporal and spatial distributions of this taxon and helps us better understand the phylogeny, evolution, and adaptive radiation of gomphotheres in early Miocene of China. [ABSTRACT FROM AUTHOR]

Abstract: It is generally believed that Miocene adakitic rocks in the Lhasa terrane (block) of Southern Tibet were derived from a thickened lower crust, and that their compositions will therefore reflect the geochemical characteristics of their lower-crustal source(s). Adakitic rocks in the western part of the Lhasa terrane possess geochemical and Sr–Nd isotopic characteristics that are clearly different from those in the eastern part of the Lhasa terrane; the former display a more enriched Nd–Sr isotopic signature together with an older model age relative to the latter, suggesting that the compositions of the lower crust under the western and eastern parts of the Lhasa terrane also differ. In addition, the adakitic rocks in the Himalayas on the southern side of the Indus–Yalu suture (IYS) have similar geochemical characteristics and Sr–Nd isotopic compositions to the adakitic rocks of the western Lhasa terrane, but differ from rocks in the eastern Lhasa terrane and from igneous rocks derived from crust beneath the Himalayas. We suggest that the lower (and/or middle) crustal materials beneath the western Lhasa terrane probably extend to the southern side of the IYS due to channel flow. If mid-lower crustal flow has occurred below Southern Tibet, the southeastward-moving anatectic mid-lower crustal material was probably derived from below the western part of the Lhasa terrane rather than the eastern. Moreover, the emplacement ages of adakitic rocks from Mayum, on the southern side of the IYS, imply that southeastward ductile flow of mid-lower crust beneath western Lhasa may have occurred as early as 17Ma. [Copyright &y& Elsevier]

SUMMARY High-grade metamorphic rocks of the upper amphibolite to granulite facies in the Higher Himalayan crystalline (HHC) were studied for their appropriateness for palaeomagnetic investigations. Sampling and fieldwork was accomplished on a south-north transect at ∼87°E in the Khumbu region south of Everest. Paragenesis of iron-sulphides and oxides was found to be variable due to different source rocks and metamorphic conditions in this area. Unblocking temperature ranges, isothermal remanence acquisition, low-temperature magnetic properties and microscopic observations confirm the presence of pyrrhotite and magnetite. Two remanence components were separated with unblocking temperature intervals of 250-330 °C and 370-550 °C, which can be attributed to characteristic remanent magnetizations (ChRM) of monoclinic pyrrhotite (ChRMpyr) and magnetite (ChRMmag), respectively. Mainly the ChRMpyr showed a consistent demagnetization behaviour, probably residing in pyrrhotite particles within the single domain to pseudo-single domain range. Normal and reverse polarities were observed, partly co-existing within the unblocking spectrum of single specimens; this (i) supports a thermoremanent (TRM) origin of the ChRMpyr and (ii) indicates that the time span of remanence acquisition was long enough to average out palaeosecular variation. The age of the ChRMpyr can be related to the last metamorphic cooling event at the Early to Late Miocene boundary (16 Ma). The ChRMmag is probably a secondary chemical or thermochemical remanence acquired by hydrothermal processes during retrogression. ChRMpyr and ChRMmag directions are similar suggesting that pyrrhotite and magnetite were magnetized approximately contemporaneously. Separation of the sampling area into three sectors reveals a south-north trend with (i) variable block rotations in the southernmost part close to the Main Central Thrust (five sites), (ii) no rotation in the area between Lukla and Namche (10 sites) and (iii) a significant clockwise rotation ( N= 5 sites, D/ I= 42.3°/29.4°, k= 20.7, α95= 17.2°) along the Imja Khola north of Namche. We interpret the clockwise rotation as an apparent rotation due to tilting by crustal doming in the Everest region. This doming obviously occurred north of a fault zone located at around Namche and was not affecting the region south of it. The clockwise sense of the apparent vertical-axis rotation indicates that the area north of Namche is located at the western side of the dome structure where westward tilting around a subhorizontal axis occurred (best fit: tilt direction 277°, tilt angle 51°). [ABSTRACT FROM AUTHOR]

The article discusses a study on the Oligocene-Miocene Kailas Formation (KF) along the Indus-Yarlung (IY) suture zone (SZ) in southwestern Tibet. The researchers investigated the effects of the tectonic setting paleography of the Kailas basin on the postcollisional tectonics of the IY suture and southern Tibet. They found that KF stratigraphy is in agreement with deposition in extension basin elongated parallel to the SZ.

The Lower Pliocene of the Linxia Basin in Gansu Province is one of only a few representative sections for the Early Pliocene sedimentary records in northern China, and even in East Asia. Recently, abundant mammalian fossils were found from the base of red clays of the Lower Pliocene Hewangjia Formation at Duikang in Guanghe County within this basin. Previously, the Pliocene mammals were sparsely found in China, and most were collected from fluvial and lacustrine deposits in the eastern Loess Plateau. Mammals from the widely distributed Pliocene Hipparion Red Clay are less in number. The known fossils from Duikang include 20 species and belong to the Shilidun Fauna. Their faunal components are similar to the Early Pliocene Gaozhuang Fauna from Yushe, Shanxi. On the other hand, some taxa from Duikang have not been found in the Gaozhuang Fauna, are slightly more primitive in evolutionary level, and appeared mainly in the Late Miocene. As a result, the age of the Duikang fossils may be slightly earlier than that of the Gaozhuang Fauna and closer to the lower boundary of the Pliocene. The Duikang fossiliferous bed is 0.8 m above the top of the Late Miocene Liushu Formation, and the first occurrence of the three-toed horse Hipparion pater can be regarded as a biostratigraphical marker of the Miocene/Pliocene boundary. In conclusion, Duikang is an ideal candidate locality to establish as the stratotype of the lower boundary of the Chinese terrestrial Pliocene. [ABSTRACT FROM AUTHOR]

Abstract: Diagnostic rock-magnetic characteristics of Miocene sequences from the western part of the Chinese Loess Plateau are used to confirm the eolian nature of sections the origin of which has been a matter of recent dispute (Alonso-Zarza et al., 2009, 2010; Guo et al. 2010). The key magnetic properties include (i) detailed correlation of both the orbitally timed and supra-orbital variations in magnetic properties between widely separated sections, (ii) the bi-modal distribution of magnetic properties with respect to particle size, reflecting in situ neoformation alongside the deposition of detrital minerals derived from the source areas, (iii) the consistent presence, in the clay fractions, of fine ferrimagnetic grains close to the superparamagnetic/stable single domain transition, all within the size range characteristic of those formed by weathering and pedogenesis under at least partially aerobic conditions, and (iv) absence of evidence for lacustrine indicators such as bacterial magnetosome assemblages, sub-oxic diagenesis or greigite formation. [ABSTRACT FROM AUTHOR]

Abstract: On a regional scale, Longgupo is found within a karstic landscape of fenglin-ouvala developed in the Triassic limestones of the Yangtze platform. After several seasons, it is now possible to define and propose a scenario for the formation of the site. During one of the intense karstification phases during the Cretaceous or early Tertiary, karstic conduits were created deep in the substratum. In concert with these deep flows and by karstic collapse, a cave was created. With the start of Himalayan uplift during the Oligocene and Miocene, the beginning of fluvial cutting was reflected by the partial erosion of the upper sandstone formations and the creation of the Miaoyu Valley. This action opened the cave, which would later be occupied by the hominid groups that interest us here. Probably at the end of the Tertiary, the cave, open at the bottom of the valley slope and facing upstream, began to be filled with alluvial deposits from the valley. The basal deposits (C III 10 of the current stratigraphic sequence, levels 20-13 of the first sequence) begin with black clays; at the Plio-Pleistocene transition, deposits become clearly alluvial, increasingly marked by reworking of surface and karstic clays and by systematically coarser contributions. During the deposition period of archaeological complexes III/III’ (previously levels 12-6), karstic collapse appears to have still been active. During the Lower Pleistocene sensu lato, the coarse nature of the deposits becomes accentuated. The material of complex II (previously levels 5-2) is a deposit that is clearly heterometric and coarse, composed at the end mainly of gravels, pebbles and more or less rounded blocks in a clayey matrix. At the conclusion of this new stage, the cave was entirely filled and, purely and simply, disappeared from the landscape. As the valley deepened during the Middle and Upper Pleistocene, the Longgupo slope underwent profound changes, the last of the limestone blocks disappeared from the slope limit and the archaeological site was protected by the coarse breccias that carpeted the slope. The main cause for the sedimentation processes at the site of Longgupo is the hydrosystem of the Miaoyu he, although injections of karstic type sensu stricto cannot be excluded. All of the arguments effectively support alluvial deposition: pebbles, an alternation of coarse and clayey beds, systematic and repeated granulometric decrease. But the stratigraphic disposition was disturbed by deformations due to gravity and karstic origins; the alluvial sediments, rendered plastic by the high proportion of clayey beds, were deformed by gravity (deformation of beds, faults, slopes) following the direction of the slope and by karstic collapse along the two limestone walls north and south of the sites (in sub-parallel faults to the south and by circular aspiration to the north). To this is added a calcitic consolidation of the upper levels that made it difficult to excavate complex C II. The stratigraphic disposition of the archaeological levels at Longgupo is now well understood. It has thus been possible to collect samples for absolute dating, to be published soon. [Copyright &y& Elsevier]

Abstract: A continuous fluviolacustrine record provides the geochronological framework to reconstruct the fluvial landscape evolution of the middle reach of the Huanghe (Yellow River). Magnetostratigraphic records from six sections at the north of the Jinshaan Gorge indicate that an isolated fluviolacustrine system occupied this gorge from 8.3 to 3.7Ma. Local fluvial incision initiated at the lake margin around 5.3-4.9Ma, and concomitant fluvial deposits intruded laterally into fine lacustrine strata increasing the sedimentation rate (ca. 3.1cm/ky) within the isolated lake. The temporal coincidence of the onset of uplift-driven valley incision at 3.7Ma along the Yellow River and the onset of basin excavation suggest that uplift possibly played an important role in the late Pliocene-Quaternary drainage evolution. Consequently, incision of the Yellow River upstream in the Jinshaan Gorge initiated at 3.7Ma. [Copyright &y& Elsevier]

Tectonic activity offshore China during the Late Miocene and Quaternary ('neotectonism') generated unconformities, resulted in depocentre migration, created new faults and initiated earthquake activity. This episode of structural disturbance, which occurred during post-rift thermal subsidence, modified pre-existing hydrocarbon accumulations and formed new pools. Constructive effects of neotectonism occurred in the Bozhong Depression, Zhu #2 Depression and the Yinggehai Basin. These effects included the formation of new structural traps, migration routes and source kitchens. Destructive effects occurred in the Xihu Depression where oil/gas fields were partially breached by post-trap peneplanation and faulting. There are pools with active gas leakage through neotectonic faults and this seems to suggest a dynamic balance between outboard leakage of gas and inboard migration of hydrocarbons. This paper summarizes understanding of the past 15 years of offshore exploration in China which has primarily focused on Neogene reservoirs. Data used for this report include extensive coverage of conventional P-wave and multi-component 2D and 3D seismic data, drilling results and extensive geochemical and geological analyses. [ABSTRACT FROM AUTHOR]

The red clay eolian sequence on the Chinese Loess Plateau (CLP) is an important archive for paleoclimate change from the late Miocene to Pliocene, and can provide significant information for the controversial problems of East Asian monsoon evolution and its forcing mechanism. In this study, we present a pollen record from Baode, northern CLP. The record shows four stages of paleoecological evolution. From 5.6-4.4 Ma, a forest steppe ecosystem developed under an extremely warm period with high seasonal precipitation. Since 4.4 Ma, a drier episode occurred, which prompted parkland landscapes to develop. During 3.5-3.05 Ma, the environment changed to a rather open steppe ecosystem with a much cooler and drier climate. After 3.05 Ma, the vegetation evolved to forest steppe. Using the percentages of arboreal plants to mirror precipitation, and comparing with other published pollen data from the CLP, we find the existence of S-N directionality of the precipitation change and high percentage of arboreal plants in the entire CLP during the Early Pliocene, which suggest the CLP was characterized by a strong East Asian summer monsoon. The strong summer monsoon corresponds well to the low global ice volume, which may illuminate global climate mechanism for the summer monsoon evolution in the early Pliocene. [ABSTRACT FROM AUTHOR]

Abstract: The cosmopolitan Solanaceae contains 21 tribes and has the greatest diversity in South America. Hyoscyameae and Mandragoreae are the only tribes of this family distributed exclusively in Eurasia with two centers of diversity: the Mediterranean–Turanian (MT) region and the Tibetan Plateau (TP). In this study, we examined the origins and biogeographical diversifications of the two tribes based on the phylogenetic framework and chronogram inferred from a combined data set of six plastid DNA regions (the atpB gene, the ndhF gene, the rps16-trnK intergenic spacer, the rbcL gene, the trnC-psbM region and the psbA-trnH intergenic spacer) with two fossil calibration points. Our data suggest that Hyoscyameae and Mandragoreae each forms a monophyletic group independently derived from different New World lineages in the early Miocene. Phylogenetic relationships within both tribes are generally well resolved. All genera of Hyoscyameae are found to be monophyletic and they diversified in middle to late Miocene. At nearly the same time, Mandragoreae split into two clades, corresponding to the MT region and the TP region, respectively. Both the phylogenetic relationships and the estimated ages of Hyoscyameae and Mandragoreae support two independent dispersal events of their ancestors from the New World into Eurasia. After their arrivals in Eurasia, the two tribes diversified primarily in the MT region and in the TP region via multiple biogeographic processes including vicariance, dispersal, recolonization or being preserved as relicts, from the mid Miocene to the late Quaternary. [ABSTRACT FROM AUTHOR]

Abstract: Dipterocarpus zhengae sp. nov. is described from the middle Miocene Fotan Group of Zhangpu county, Fujian Province, Southeast China on the basis of a fruit wing. Three kinds of venation of the calyx longer lobes (enlarged sepals) occur in the winged fruits of extant Dipterocarpus. The fossil species is referred to the kind having three primary veins and within that category is most similar to extant Dipterocarpus gracilis Blume in the size of the longer lobe as well as its venation. The occurrence of the fruit wing of Dipterocarpus, together with palynological evidence, indicates unequivocally that a tropical climate and tropical rain forest occurred in Zhangpu during the middle Miocene, warmer and more humid than at the present day. The palaeobiogeography of Dipterocarpus is reviewed. [ABSTRACT FROM AUTHOR]

Abstract: Quantifying the elevation history of the 2000km-wide Tibetan Plateau to an average elevation of 5km is important for understanding key aspects of Cenozoic global climate change, collision tectonics and the evolution of the Asian monsoon, yet quantitative measures of Cenozoic surface height change across Tibet remain few and are sometimes contradictory. Here we report the first exploratory application of a modified Co-existence Approach (CoA) using previously published fossil pollen records to reconstruct quantitatively the Cenozoic minimum palaeoaltitudes of Gangdise-Nyainqentanglha Area of the Tibetan Plateau. GCM simulations were used to adjust Eocene and Miocene raw CoA values for secular climate change and changes in palaeolatitude. This modelled correction increased the CoA-derived altitudes by 895±96m to give a minimum overall Eocene altitude of 3295–3495m. The Miocene correction factor of 481±25m gave an overall minimum altitude estimate of 3000–3150m. For the Holocene CoA returns four equally likely elevations of 4800–4950m, 3800–3900m, 3000–3100m and 2900–3000m. The first of these is indistinguishable from the present day regional average while the others suggest significant upslope pollen transport. Both the Eocene and Miocene palynologically-derived height estimates are consistent with suggestions of significant core plateau elevation by the Eocene, but are likely to underestimate the true palaeoelevation due to pre-Himalayan upslope pollen transport. [ABSTRACT FROM AUTHOR]

Abstract: Crustal movement around and away from the Namche Barwa syntaxis is indicated in the Asian velocity field inferred from GPS data and Quaternary fault slip rates. Nevertheless, there is a limited field-based control on the rotational history of the north-eastern Himalayan arc. Exploring the poly-phase nature of deformation, within the Cretaceous diorite dykes and their host-rock (Triassic flysch), in the eastern Tethyan Himalaya (90°–92°E), combined with new remote sensing data and existing thermo-geochronological data, allow us to unravel the kinematic relationship between paleomagnetic remanence vectors and the deformation phases. Decay at 325°C in high temperature susceptibility curves and in the thermal demagnetization of the SIRM indicate that the characteristic remanent magnetization in the Cretaceous diorite dykes is carried by pyrrhotite. The pyrrhotite component unblocks at 280–350°C, revealing normal and reverse polarities. It is of post-folding origin with a mean remanence direction of 019°/28° and 001°/20° in the eastern (Qonggyai valley) and western (Nagarze) part of the sampling area, respectively. The ~22Ma K–Ar age of the last metamorphic event support that the remanence is post-Eohimalayan folding and likely of thermoremanent or thermo-chemical origin. Comparison of the declination with respect to the Early-Miocene reference direction, yields a trend from no apparent rotation in the west to 20° clockwise rotation in the east with respect to the stable Indian plate. This result can be kinematically related to the Middle to Late-Miocene strain partitioning between far-field southeast extrusion of SE Tibet and near-field strike-slip faulting and E–W extension. Furthermore the observed pattern of tilting around horizontal axis may reflect concealed North Himalayan doming. [ABSTRACT FROM AUTHOR]

Abstract: This study reports the first observation of predominant even C-numbered n-alkanes from sediments in the continuous lacustrine-sedimentary section (Maogou) from the Late Miocene to the Early Pliocene (13–4.4Ma) in the Linxia Basin, NE Tibetan Plateau. The n-alkanes showed a bimodal distribution that is characterised by a centre at n-C16–n-C20 with maximum values at n-C18 and n-C27–n-C31 as well as at n-C29. The first mode shows a strong even C-number predominance (OEP16–20 0.34–0.66). In contrast, the second mode has a strong odd C-number predominance (OEP27–31 1.20–2.45). Certain types of special autochthonous bacteria are a possible source for this distribution of even C-numbered n-alkanes in lacustrine sediments. These bacteria may have a high production rate in weak oxic–anoxic and arid depositional environments, in which a variety of geochemical parameters have recorded palaeoclimate change. [ABSTRACT FROM AUTHOR]

Abstract: Recent studies of the eolian deposits in northern China have extended the East Asian monsoon history back to the early Miocene. However, the relative intensities of monsoonal winds and precipitation and the extent of their coupling prior to the Pleistocene epoch remain poorly constrained, mainly due to uncertainties in the interpretation of proxy indices generated from the Mio–Pliocene Red Clay sequences. Here we reconstruct East Asian monsoon oscillations over the past 7Ma using magnetic susceptibility and carbonate content as summer monsoon (precipitation) proxies, and quartz grain size as a winter monsoon (wind intensity) index. Our results suggest that precipitation and wind intensity exhibited significant orbital-scale variations prior to 4.2Ma, followed by slightly damped variability between 4.2 and 2.75Ma. Subsequently, East Asian monsoon circulation experienced two large shifts at about 2.75 and 1.25Ma, characterized by stepwise strengthening of glacial wind and interglacial precipitation. A remarkable change in East Asian monsoon seasonality occurred around 3.15–2.75Ma. Prior to 3.15Ma, strong winds were positively correlated with high effective precipitation, whereas after 2.75Ma strong winds were negatively correlated with heavy precipitation. This shift was probably induced by a change from an insolation-forced system to one strongly influenced by the combined effects of the phased uplift of the Himalaya–Tibetan Plateau and the simultaneous development of the Northern Hemisphere ice sheets. [ABSTRACT FROM AUTHOR]

Abstract: The recently discovered large Nanpu Oilfield is located in the NW part of the Bohai Bay Basin, eastern China. Extensive drilling and geophysical research have revealed widespread occurrence of Eocene to Miocene mafic volcanic rocks. On the basis of stratigraphic constraints, three cycles of volcanism have been recognised. Petrological and geochemical studies of drill core samples indicate that most of these mafic rocks are alkaline basalts. Some basalts experienced fractional crystallization, dominated by clinopyroxene and FeTi oxides. All samples have trace elements patterns similar to oceanic island basalts (OIB). Sr and Nd isotopic analyses show that 87Sr/86Sri values range from 0.703577 to 0.708160 and εNd(t) varies from 0.7 to 6.8. Pb isotope analyses yield Pb ratios ranging from 17.43 to 19.19 for 206Pb/204Pb, from 15.43 to 15.67 for 207Pb/204Pb and from 37.35 to 38.64 for 208Pb/204Pb. The trace element and isotopic characteristics indicate that the Nanpu Sag basalts are similar to oceanic island basalts possibly with some contributions of subcontinental lithospheric mantle. Considering that there is widespread and coeval basaltic volcanism in the Bohai Bay Basin, which has comparable geochemistry, we adopt a model of episodic upwelling and melting of asthenospheric mantle for the origin of these basalts. The old subcontinental lithospheric mantle had interacted with new asthenospheric mantle-derived melts. The replacement of old North China Craton mantle to new and fertile asthenospheric mantle is still ongoing. Early-stage magmas were generated from deeper in the mantle with a higher degree of partial melting than late stage magma. The upward migration of the melting column supported active asthenosphere mantle upwelling or mantle plume induced magmatism under an extensional regime. [Copyright &y& Elsevier]

Abstract: The Lao Cai, Yen Bai and Bao Yen Basins connected with the Red River Fault Zone (RRFZ) are filled with over 1000m thick Neogene (Miocene) clastic deposits of different type and origin. Coarse-grained alluvial deposits predominate along the south-western margin of the Lao Cai and Yen Bai Basins, while different types of conglomerates and sandstones, even siltstones occur in their central and along their north-eastern parts. Such asymmetry in the cross-section basin fill points to the south-western active margin of these basins. Three main facies associations composed of 12 lithofacies have been recognized in the Miocene succession filling the studied basins: (1) debris-flow dominated alluvial fan association, (2) sheetflood dominated alluvial fan association, and (3) lacustrine association. Both alluvial fan facies associations are broadly spread in the studied basins, especially along their south-western margins. The debris-flow dominated deposits are represented by decimetre to several meters thick, sand- and mud-supported disorganized pebble- to cobble-size, occasionally boulder breccia and conglomerate beds. The sheetflood dominated deposits are represented by alternating planar-bedded pebble and cobble gravel couplets. The occurrence of conglomerate bodies within and overlapping fine deposits of the lacustrine facies association may suggest deposition in a debris-flow and sheetflood dominated alluvial-fan setting associated with narrow, elongated basins that could be occupied by lakes and bordered by active fault scarps. The facies pattern of the particular basins is connected with the evolution of the RRFZ. The origin of these basins may be correlated with a sinistral transtensional regime which occurred in the Early to Middle Miocene. Moreover, the high-grade metamorphic core of the Day Nui Con Voi Massif, presently the main structural element of the RRFZ, was probably not exposed during sedimentation of most of the strata in the studied basins. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: The relationships between climate, topography, and erosion are significant in understanding landscape evolution. In order to study this relationship in a tectonically active landscape, the details of 11 drainage basins were collected from Qilian Shan Mountains. Decadal-scale erosion rates, including the mechanical load and solute load contributions, are estimated in natural conditions. The calculated erosion rates show that the average erosion rate of Qilian Shan Mountains is about 0.08mm/yr, while the variation of annual erosion rates within each basin is significant. The changes of topography and climate, which potentially control erosion rates, are also employed in this paper for correlating analyses. Correlation analyses indicate that erosion rates are more closely correlated with topographic variables, such as mean local relief and mean slope, than all of the climatic variables; and mean local relief and decadal-scale erosion rates show a linear relationship in these tectonically active mountains. However, some topographic variables like basin area and elongation ratio exert limited influence on erosion rates; while others, such as basin elevation, basin relief and basin roughness, show poor correlation. The results indicate that topographic control, like aspects of the local terrain steepness, plays the most important role in spatial distribution of decadal-scale erosion rates throughout Qilian Shan Mountains. Under topographic control, some climatic variables, like discharge and runoff, however, could account for the significant variation of annual erosion rates in individual basin. When comparing erosion rates on different timescales, we found that the decadal-scale erosion rates are lower than the long-term river incision rates, as well as the exhumation rates during early and middle Miocene. The change to more arid climatic condition since the middle Miocene combining with tectonic uplift should attribute to the inconsistent erosion rates over different timescales in Qilian Shan Mountains. [Copyright &y& Elsevier]

Abstract: Modern erosion of the Himalaya, the world''s largest mountain range, transfers huge dissolved and particulate loads to the ocean. It plays an important role in the long-term global carbon cycle, mostly through enhanced organic carbon burial in the Bengal Fan. To understand the role of past Himalayan erosion, the influence of changing climate and tectonic on erosion must be determined. Here we use a 12Myr sedimentary record from the distal Bengal Fan (Deep Sea Drilling Project Site 218) to reconstruct the Mio-Pliocene history of Himalayan erosion. We use carbon stable isotopes (δ 13C) of bulk organic matter as paleo-environmental proxy and stratigraphic tool. Multi-isotopic — Sr, Nd and Os — data are used as proxies for the source of the sediments deposited in the Bengal Fan over time. δ 13C values of bulk organic matter shift dramatically towards less depleted values, revealing the widespread Late Miocene (ca. 7.4Ma) expansion of C4 plants in the basin. Sr, Nd and Os isotopic compositions indicate a rather stable erosion pattern in the Himalaya range during the past 12Myr. This supports the existence of a strong connection between the southern Tibetan plateau and the Bengal Fan. The tectonic evolution of the Himalaya range and Southern Tibet seems to have been unable to produce large re-organisation of the drainage system. Moreover, our data do not suggest a rapid change of the altitude of the southern Tibetan plateau during the past 12Myr. Variations in Sr and Nd isotopic compositions around the late Miocene expansion of C4 plants are suggestive of a relative increase in the erosion of High Himalaya Crystalline rock (i.e. a simultaneous reduction of both Transhimalayan batholiths and Lesser Himalaya relative contributions). This could be related to an increase in aridity as suggested by the ecological and sedimentological changes at that time. A reversed trend in Sr and Nd isotopic compositions is observed at the Plio-Pleistocene transition that is likely related to higher precipitation and the development of glaciers in the Himalaya. These almost synchronous moderate changes in erosion pattern and climate changes during the late Miocene and at the Plio-Pleistocene transition support the notion of a dominant control of climate on Himalayan erosion during this time period. However, stable erosion regime during the Pleistocene is suggestive of a limited influence of the glacier development on Himalayan erosion. [Copyright &y& Elsevier]

Abstract: Post-collisional (26–10Ma) high Sr/Y and HREE-depleted intrusive rocks occur in an E–W trending belt paralleling the Yarlung–Zangbo suture in south Tibet. Their petrogenesis has been a subject of debate. Here, we present chronological, geochemical and Sr–Nd–Hf isotopic data for two newly discovered large-volume high Sr/Y granitoids (the Pagu granodiorite and the Nanmuqie granite) and three high Sr/Y porphyries intruding the granitoids in the Lhasa terrane. LA-ICP-MS zircon U–Pb dating for the Pagu granodiorite and Nanmuqie granite yielded identical magma crystallization ages of 14.0–14.4Ma, which is indistinguishable from their associated high Sr/Y porphyries (14.2–14.6Ma). The granitoid was intruded at middle-crust depth, whereas the porphyry was intruded at upper-crust depth, indicating that the Lhasa terrane has experienced a rapid crustal uplift during the high Sr/Y magma emplacement. Zircon Hf isotopic and whole-rock Sr–Nd isotopic compositions for these granitoids and porphyries suggest that their magmas were dominantly derived from partial melting of crustal materials. The granitoids and porphyries have ε Hf(t) values overlapping with the mafic granulites in the Himalayan terrane (Indian plate). Their Sr–Nd isotopic compositions show two-endmember mixing between the Himalayan mafic lower crust and the ultrapotassic lavas/the Lhasa lower crust. We suggest that the high Sr/Y magmas in the Lhasa terrane could be derived from partial melting of subducted Indian mafic lower crust with incorporation of the ultrapotassic lava and/or the Lhasa lower crust components. Our study suggests a new model for the high Sr/Y magma generation in the Lhasa terrane and provides a line of geochemical evidence that the Indian continental crust was subducted beneath the southern Lhasa terrane in the early–middle Miocene. [Copyright &y& Elsevier]

Abstract: The Tianshui Basin in central China contains a thick sedimentary sequence (~1400 m) of continental deposits, Aragonian to Villafranchian (Miocene-Pliocene) in age. Intense Himalayan movements around the Paleogene/Miocene boundary triggered the uplift of mountain ranges around the Tianshui Basin, providing the deposition site for continental sediments. The sedimentary infill of the basin consists of four stratigraphic units (I to IV). This paper focuses on Unit II. Most of the accommodation space was occupied by Unit I, so during the sedimentation of Unit II, the morphology of the basin was relatively flat, promoting the development of wide distal fan/mudflat areas and wide shallow lakes. Deposits include: red mudstones, pedogenic and groundwater calcretes, reworked calcrete deposits, sheet-floods, fluvial channels, rippled sandstones/siltstones, ooidal/peloidal packstones, palustrine limestones, bioturbated marls and intraclastic limestones/marls. The characteristics and organization of the deposits indicate the gradual transition from alluvial to lake environments. Within the distal fan/mudflat, the deposition of reworked calcrete clasts as one of the most striking facies of the basin may be attributed to substantial recycling of calcrete levels and red clays. At the lake margins, the presence of ooids and palustrine limestones suggests the possibility of ramp-like margins within different energy settings. The origin of some of the deposits of the basin''s QA-I section is under discussion, and their consideration as eolian has been recently proposed. However, we believe this possibility is precluded by the characteristics of the deposits. Our proposal has important implications for revising the interpretation of Miocene paleoclimatic conditions in central Asia. [Copyright &y& Elsevier]

Abstract: 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 CO2 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 δ 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 δ 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. [Copyright &y& Elsevier]

Abstract: The mid-Miocene Gangdese orogenic belt in southern Tibet contains porphyry Cu deposits that developed after the Indian–Asian continental collision in the early Cenozoic. Field work confirms that these porphyry Cu deposits are temporally and spatially associated with mid-Miocene monzogranitic and quartz monzonitic stocks, which intruded Mesozoic–Cenozoic Gangdese granitoid batholiths and surrounding Triassic–Tertiary volcano-sedimentary sequences in the Lhasa Terrane, and formed a 50-km wide, 400-km long E–W belt. Magmatism occurred during the interval 11.2 to 19.7 Ma, peaking at ∼16 Ma for the porphyry stocks; this is consistent with the age (10 to 18 Ma) of the east–west extension and subsequent NS-striking normal fault systems (≥13.5 Ma) in the Tibetan Orogen. The stocks typically occur as multiple small diameter intrusions (<5 km), and have shallow emplacement depths (∼1 to 3 km). The Cu porphyries are shoshonitic and high-K calc-alkaline, showing geochemical affinities with adakites. The porphyries were derived from a thickened basaltic lower-crust source, rather than from the subducted oceanic-slab. Geochemical and geophysical data indicate that during the Paleocene–Oligocene mantle-derived mafic magmas created a newly-formed basaltic underplate at the bottom of the lower-crust, which undewent garnet amphibolite metamorphism under high pressure (>50 km). Breakdown of hornblende in the juvenile lower-crust source during melting is regarded as fundamental for the formation of the fertile adakite and porphyry Cu systems in south Tibet. The Gangdese belt contains four large, and three intermediate- and small-sized porphyry Cu–Mo deposits, and shows a continuous spectrum from typical porphyry-type Cu–Mo to skarn-type Zn–Pb mineralization. Twenty-three samples collected from four deposits yielded a limited range of molybdenite Re–Os isochron ages from 15.2 to 16.0 Ma, similar to previously-reported Re–Os ages (13.8 to 14.9 Ma) for other porphyry Cu–Mo deposits in the belt, suggesting that Cu–Mo mineralization in the belt occurred in a post-collisional extension environment. The characteristics of porphyry Cu–Mo deposits in the collisional zone are similar in many aspects to those in arc settings, i.e., mineralization style, alteration zoning, and metal association. Preliminary fluid inclusion studies indicate that the early hydrothermal fluids are preserved as high temperature (≥450 °C), high salinity (40 to 47 wt.% NaCl equiv.) and high pressure (≥1100 to 1500 bar) fluid inclusions. These fluids are interpreted to represent an orthomagmatic fluid that boiled episodically due to fluid overpressuring and hydrofracturing, resulting in potassic alteration and precipitation of chalcopyrite–molybdenite assemblages. On the basis of comparison with porphyry Cu deposits in arc settings, we proposed that melting of thickened, newly-formed basaltic crust resulted in generation of Cu-bearing magmatic systems in the Tibetan collision zone, and both orogen-transverse normal faults and orogen-parallel thrust zones during the Miocene post-collisional extension constrain the temporal and spatial localization of the porphyry Cu systems in the collision zone. [Copyright &y& Elsevier]

Abstract: Deep subduction of lower continental crust to mantle depths has been recognized in outcrops and drill cores of eclogites and other ultra-high pressure (UHP) rocks of the Sulu intra-continental orogenic belt. In a search of evidence for such subducted crustal sources of melts, we study the elemental and isotope geochemistry of basalts from Anfengshan, a Miocene volcano located in the Sulu UHP belt, as well as Nd–Hf isotopes of eclogites from the Sulu belt itself. The Anfengshan basalts are basanites and nephelinites with low SiO2, high incompatible element contents, positive Nb, Ta, Sr, and negative K, Pb, Zr, Hf, and Ti anomalies. Radiogenic isotopes (87Sr/86Sr=0.70337–0.70359, εNd =+5.1–+6.7, εHf =+10.6–+12.3, 206Pb/204Pb=17.5–18.0) show some highly unusual correlations: εNd correlates positively with 87Sr/86Sr, but negatively with εHf. 87Sr/86Sr, 143Nd/144Nd, and 206Pb/204Pb ratios all correlate negatively with ΔεHf (= deviation from the global εHf–εNd correlation). The correlations form two distinct mixing arrays with one common, high-εNd end-member. Superchondritic Zr/Hf ratios (~55), and negative Zr, Hf, Ti anomalies indicate that the common mantle source component has been metasomatized by carbonatitic liquids. We suggest that the other two source components are eclogites derived from subducted lower crust: both of these differ from ordinary mantle components by their low 87Sr/86Sr and low εNd and 206Pb/204Pb, but high ΔεHf. The εNd–εHf values of the eclogites form two groups, both of which lie close to the Hf–Nd mantle array, and are therefore not direct analogues of possible source eclogites for the basalts. We explain the shift toward high ΔεHf-basalt sources as follows: an early Cretaceous igneous event extracted partial melts from the eclogites residing in the mantle, thereby increasing their (residual) Lu/Hf ratios, while changing Sm/Nd only slightly. During the Anfengshan melting event, these garnet-rich sources produced melts with low Zr/Hf and increased Nb/Nb*, Hf/Hf*, Sm/Yb ratios relative to the peridotitic source end-member. We therefore suggest that the eclogites represent the residues of mafic lower continental crust subducted during the Triassic continent–continent collision. This interpretation is supported by recent seismic tomography, which revealed a high-velocity anomaly in the uppermost mantle beneath the Sulu belt. [Copyright &y& Elsevier]

Abstract: The Early Miocene palynological assemblage of Guangfayong (GFY) in the Weichang District, Hebei Province, China has been studied. It consists of 48 palynomorphs belonging to 39 families, with pollen and spores belonging to angiosperms (28.9%), gymnosperms (59.9%), ferns (10.8%) and other elements (0.5%). Based on the palynological assemblages of GFY and Wuluogong (WLG), another locality in the Weichang District, the Early Miocene vegetation of the Weichang District, was characterized by a mixed temperate forest of conifers (e.g. Pinus, Picea, Tsuga) and broad-leaved trees (e.g. Betula, Alnus), with some subtropical plants (e.g. Carya). The palaeoclimatic parameters of Guangfayong were obtained by applying the Coexistence Approach: the mean annual temperature from 7.8 to 14.9 °C, the difference of temperature between the coldest and warmest months from 14.2 to 23 °C, the mean temperature of the coldest month from −3 to 5.9 °C, the mean temperature of the warmest month from 23.5 to 25.4 °C, the mean annual precipitation from 658.7 to 1389.4 mm, the minimum monthly precipitation from 7.6 to 16.4 mm, and the maximum monthly precipitation from 161.4 to 205.9 mm. It suggests a warm temperate to subtropical climate in Weichang District, similar to that of present-day Zhaojue City, Sichuan Province in the Yangtze River Valley. When the palaeoclimatic parameters were compared with those of Middle Miocene Shanwang Basin, it would seem that the temperature and precipitation were a little higher in the Middle Miocene of eastern China. However, if the latitudinal temperature gradient at that time is considered, the median temperature values of GFY of Early Miocene and Shanwang of Mid-Miocene were similar. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: Major elements, highly siderophile elements (HSE) and Re–Os isotope ratios were analysed in situ on individual sulfide grains in spinel peridotite xenoliths hosted by Miocene intraplate basalts from the Penghu Islands, Taiwan. The xenoliths represent texturally and compositionally different mantle domains, and the geochemical characteristics of the sulfides show changes in HSE distribution and Re–Os isotope systematics, produced as their host rocks were metasomatised by percolating fluids/melts. In prophyroclastic and partly metasomatised peridotites from the Kueipi (KP) locality, the sulfides have subchondritic to superchondritic 187Re/188Os and 187Os/188Os ratios. Many of these sulfides reflect fluid/melt interaction with residual MSS and/or crystallization of fractionated sulfide melts, which produced high contents of Cu and PPGEs and high Re/Os; inferred melt/rock ratios are low. In contrast, sulfides in equigranular and extensively metasomatised peridotites from the Tungchiyu (TCY) locality are mainly more sulfur-rich Ni–(Co)-rich MSS, with subchondritic to chondritic 187Os/188Os and subchondritic 187Re/188Os. These sulfides are interpreted as products of interaction between pre-existing MSS and percolating silicate melts. Melt/rock ratios were high and the percolating melt was less differentiated than the melt that percolated the KP peridotites. Sulfides in a TCY pyroxenite are mainly MSS; they have the lowest HSE contents, subchondritic to superchondritic 187Os/188Os and subchondritic 187Re/188Os, and may have precipitated from sulfide melts that segregated from basaltic melts under S-saturated conditions. In most sulfides melt percolation appears to have induced fractionation among the HSEs and disturbed Re–Os isotope compositions. Despite the metasomatic effects, rare residual MSS, sulfides that from crystallised sulfide melts and sulfides modified by addition of Re (with no evidence for Os addition) can still provide useful chronological information. Such sulfides yield T RD age peaks of 1.9, 1.7–1.6, 1.4–1.3 and 0.9–0.8 Ga, which may record the timing of melt extraction and/or metasomatic events in the mantle. These periods are contemporaneous with the major crustal events recorded by U–Pb dates and Nd and Hf model ages in the overlying crust. This close correspondence indicates that the sulfide T RD ages reflect the timing of lithosphere-scale tectonothermal events (such as melting and metasomatism) that affected both the lithospheric mantle and the overlying crust. The sulfide T RD ages, taken together with the crustal data, suggest that most of the Cathaysia block had formed at least by Paleo-Proterozoic time, and that some domains are Archean in age. [Copyright &y& Elsevier]

The first record of the genus Pliocaenicus from middle Miocene deposits is presented in this paper. This record from Changbai (Jilin Province, China) places the origin of the genus further back into themiddleMiocene. The genus has been so far reported from the late Miocene/early Pliocene till Recent. The population from Changbai belongs to the group of Pliocaenicus species possessing complex alveolae, such as P. cathayanus Wang, P. jilinensis Wang and P. omarensis (Kuptsova) Stachura-S. et Khursevich. Both P. cathayanus and P. jilinensis have been described from China (Pliocene deposits), and are only known from the type locality. The third species, P. omarensis is reported from Eurasia and Africa (age range: late Miocene-Pleistocene). In this report we describe P. changbaiense, a new species from China, and focus on those characters having the potential for developing further an evolutionary and taxonomical concept in Pliocaenicus. We anticipate that these will contribute to our understanding of the driving forces of diatom dispersal. [ABSTRACT FROM AUTHOR]

Abstract: Investigations of the deformation history of the Himalayan orogen support interpretations of rapid and striking changes in the landscape of the Tibetan Himalaya and High Himalaya. We examine this issue by integrating oxygen isotope-based paleoelevation reconstructions of the Zada basin in southwestern Tibet with information on the structural evolution of the High and Tibetan Himalaya between 79°E and 84°30′E. δ18Opsw values were calculated from δ18Occ values from pristine fluvial Miocene gastropod shells. Analyses comparing the most negative δ18Osw and reconstructed δ18Opsw values to Δδ18Osw versus elevation relationships based on both thermodynamic models and an empirical data set suggest a decrease in the mean watershed elevation of 1 to 1.5 km since the Late Miocene. Geologic mapping and structural data from crustal scale fault systems in the Zada region and regions to its east indicate a phase of arc-normal shortening and vertical thickening since the Middle Miocene, followed by ongoing arc-parallel extension and vertical thinning. These results suggest that regions in this part of the orogen transitioned from undergoing arc-normal shortening to arc-parallel extension in the Late Miocene, and that arc-parallel extensional structures root deeply within the Himalayan thrust wedge. When combined with data on the distribution, age, and provenance of sedimentary basins, our geologic mapping, structural data, and paleoelevation results suggest that this transition from shortening to extension was accompanied by a topographic inversion from mountains to basins in <4 m.y. These observations can be explained by a foreland propagating fault system that accommodates outward radial expansion of the Himalayan orogen. [Copyright &y& Elsevier]

Abstract: The East Asian monsoons have fluctuated in concert with high-latitude warmth during the past several hundred thousand years, with humid summer monsoon-dominant climates characterizing warm intervals, including interglacials and interstadials, and arid winter monsoon-dominant climates characterizing cool intervals, including glacials and stadials. Of the states comprising the mid-Pleistocene to recent climatic regime, interglacials are most similar in terms of high latitude ice volumes and temperatures to those extant during the late Miocene and early Pliocene. Thus, an important question is whether Mio-Pliocene climates in northern China were analogous to a hypothetical ‘prolonged interglacial state,’ with increased summer monsoon precipitation and expansion of forest and steppe environments at the expense of desert environments. We utilize new and previously published carbon isotopic data from fossil teeth and soil carbonates to place constraints on paleovegetation distributions and to help infer the behavior of the monsoon system between ∼7 and 4 Ma. We find that plants using the C4 photosynthetic pathway—which today are largely grasses found in regions with warm season precipitation—were present in northern China by late Miocene time, demonstrating that the C4 expansion in China was not significantly delayed compared to the global C4 event. During the late Miocene–early Pliocene interval, soil carbonate and tooth enamel δ13C data indicate: 1) that nearly pure C3-plant ecosystems existed in the southern Chinese Loess Plateau (CLP), and therefore ecosystems there were dominated by woody dicot, herbaceous dicot, or cool-season grass vegetation (or a combination of these), and 2) that the CLP was characterized by a pattern of northward-increasing C4 vegetation and aridity. Utilizing a broadened conceptual model for interpreting δ13C data, and citing independent faunal, floral, and lithostratgraphic data, we suggest that these patterns reflect northward expansion of forest and steppe ecosystems and relatively humid monsoon climates during the late Miocene and early Pliocene. An important implication of this interpretation is that the forcing mechanism illuminated by the temporal correlation during the Pleistocene between warm high latitudes and strong East Asian summer monsoons is a robust feature of the Eurasian tectonic–climatic system that predates the Plio-Pleistocene climatic reorganization. [Copyright &y& Elsevier]

Abstract: Variations in the volume and age of Miocene granites and in mid-crustal conductance from the northwest Himalaya to southeastern Tibet imply lateral differences in late orogenic processes. The change from west to east occurs near the Gurla Mandhata dome, where the Karakoram fault terminates and merges with the Indus–Yarlung suture zone. The ‘channel flow’ model, developed in southeastern Tibet, predicts that anatectic partial melts beneath the Tibetan plateau are gravitationally-driven south to a topographic erosional front and are exposed as leucogranites in the Greater Himalaya Sequence; upwellings of these channel granites occur as gneiss domes in the Tethyan Himalaya Sequence. Published magnetotelluric profiles show high conductivity 30–40 km deep beneath Tibet from c. 400 km north of the Main Frontal thrust south across the suture zone, beneath the Himalayan gneiss domes, and to the topographic front; this conductive middle crust corresponds to 2–4% partial melt in the northwest Himalaya and 5–12% melt in southeastern Tibet, sufficient in the latter case to weaken rock for flow. East of the Karakoram termination leucogranites are abundant and are as young as 7 Ma; west of the termination, channel granites are less abundant and no younger than 18 Ma. Middle Miocene (16–14 Ma) leucogranites are found in the Karakoram fault zone located north of the suture zone and south of the proposed anatectic melt source. The initiation of motion on the crustal-penetrating Karakoram fault at 25–21 Ma may have created a barrier to the southward flow of mid-crustal melts and acted as a vertical conduit for these same melts. [Copyright &y& Elsevier]

Abstract: Ningxiatherium euryrhinus sp. nov. is a relatively large elasmothere rhino from the Linxia Basin in northwestern China found in the early Bahean, which corresponds to the early Vallesian (MN9), ca. 11.1Ma. It is much larger than the extant Ceratotherium simum and has a single horn. Ningxiatherium is similar to the late Miocene Parelasmotherium from Gansu and Shanxi, but differs in having partially ossified nasal septum, terminal nasal horn boss, shallower nasal notch above the P3/P4 boundary, and much shorter premolars. N. euryrhinus sp. nov. differs from N. longirhinus from the late Miocene of Zhongning, Ningxia in northwestern China by its larger size, relatively wider nasals, shallower nasal notch, and sub-quadrangular occlusal surface of M3. In the Linxia Basin, the other early late Miocene (Bahean or Vallesian) elasmotheres are known from complete skulls or isolated teeth. They include two genera and three species: Parelasmotherium linxiaense, P. simplum, and Iranotherium morgani. They lack a nasal septum, but Ningxiatherium has one. The age of N. euryrhinus is early late Miocene based on direct association with biochronologic indicator taxa, such as Dinocrocuta gigantea, Hipparion dongxiangense, and Chilotherium primigenius. N. euryrhinus is more primitive than N. longirhinus sp. nov. in having a sub-quadrangular M3, a shallower nasal notch, and the presence of DP1 in adults. [Copyright &y& Elsevier]

Lacustrine strata of the Wudaoliang Group demonstrate that two vast lake complexes covered the central Tibetan Plateau during early Miocene time. The Wudaoliang Group, which is characterized by dolostone, limestone, and marl as thick as 310-350 m, miles horizontally or with a slight dip above Oligocene reddish-brown sandstone, and is covered by upper Miocene and Pliocene mudstone and sandstone. The extensive distribution of this group outlines interconnected lake basins of 5000-15,000 km² or larger in the north-central Tibetan Plateau, such as the Wudaoliang, Beiluhe, Tuotuohe, Tongtianhe, and East Wenquan Basins, and lake basins 2000 km² or larger in the southcentral plateau, such as the Ando, Naqu, Bangoin, Lunpola, and Shuanghu Basins. These lake basins, separated by mountain ranges and islands, were linked by water passages in early Miocene time, when they apparently formed a huge lake complex that covered as much as 100,000 km² in the north-central Tibetan Plateau and another one >50,000 km² in the south-central part of the plateau. Such immense lakes existed for several million years between ca. 23.5 and ca. 13.5 Ma after the Tibetan Plateau rose, and their interconnected basins define the topography during early Miocene time. The fossils contained in these basins indicate a change from the warm, dry climate of the Oligocene to moderately cool and wet conditions at the beginning of the early Miocene, followed by progressive cooling and drying, which suggests continuous uplift during deposition of the Wudaoliang Group. [ABSTRACT FROM AUTHOR]

There is lively debate on whether Asian plate material was involved in southward flow of mid-lower crust in a ductile channel beneath southern Tibet. One argument against such involvement is the apparent absence of material derived from Asian lithosphere within the High Himalayan Series (Indian plate) that could represent the putative channel. A north-south—trending mid-Miocene dike swarm that intrudes the Tethyan sedimentary cover of the Sakya gneiss dome (Indian plate) yields new Sr-Nd isotopic data (87Sr/86Sr = 0.7071-0.7079; ϵNd -4 to -6) indicating that these melts share the same source as Miocene dacitic dikes from north of the Indus-Tsangpo suture. Moreover, dikes on both sides of this suture represent crustal melts derived largely from mid-lower crust of the Asian plate, exposed today as the Nyainqentanglha gneisses that underlie the Gangdese batholith. We infer that melting of the Asian lithosphere extended south of the surface trace of the suture, requiring southward propagation of anatectic Asian middle crustal material during the Miocene. The emplacement ages of the southern dike swarm (12-9 Ma) thus delimit the timing of active southward ductile flow of Asian material. [ABSTRACT FROM AUTHOR]