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The detailed lithospheric structure of South China is the basis for the understanding of tectonic processes of eastern China. Specifically, two essential issues in the study of lithospheric structure are the thermal and compositional structures, which are usually derived from either geophysical or geochemical observations. However, inversions from single geophysical or geochemical datasets have certain limitations, making it necessary to develop joint inversions of geophysical, geochemical and petrological datasets. In this paper, through thermodynamic simulation and probabilistic inversion, we inverted multiple datasets including topography, geoid height, surface heat flow and surface wave dispersion curves for the 3D lithospheric thermal and compositional structure of South China. The results reveal a thin (< 100 km) and flat LAB beneath the South China Fold System Block and the lower Yangtze Craton. Also, we found that the lithospheric mantle is primarily composed of saturated peridotite, indicating that the ancient refractory lithospheric mantle has been replaced by new materials. The dominant dynamic mechanism for lithospheric thinning in eastern South China may be the flat subduction of ancient Pacific slab, while thermal erosion may have also played a significant role. In contrast, the LAB depth beneath the Sichuan Basin is much thicker (> 200 km), suggesting that the thick and cold craton lithospheric roots are retained. There may exist a discontinuous interface beneath the Sichuan Basin, with the saturated lower layer thicker than the refractory upper layer. As a result, the lithospheric mantle of the Sichuan Basin and surrounding regions is mainly composed of saturated and transitional peridotite. [ABSTRACT FROM AUTHOR]

Adakitic rocks in continental settings are commonly considered to be formed by partial melting of thickened or delaminated lower crust. Investigations on this kind of rocks can provide important information about crustal evolution complementary to information from other rocks. This paper reports adakitic granodiorite of the Lingxi pluton in the interior of the Cathayisa Block. LA-ICP-MS zircon U-Pb dating shows that it was formed in the late Early Cretaceous (100±1 Ma). The granodiorite has geochemical features of adakitic rocks derived from partial melting of the thickened lower crust, e.g., high SiO (mainly ranging from 64.4 to 68.9 wt.%) and Sr (624-894 ppm) contents, Sr/Y (49.9-60.8) and La/Yb (23.4-42.8) values, low Y (10.3-17.1 ppm), Ni (5.62-11.8 ppm) and MgO (mostly from 0.86 wt.% to 1.57 wt.%) contents and weak Eu anomaly. It has initial Sr/Sr ratios of 0.7086-0.7091, ε ( t) values of −6.2 to −5.9 and zircon ε ( t) values mostly of −10.1 to −7.6. Based on the geochemical characteristics and simple modelling, it is suggested that the most likely generation mechanism of the Lingxi granodiorite is partial melting of a thickened Proterozoic lower continental crust at a pressure ≥12 kbar (or crust thickness ≥40 km), leaving a garnet-bearing amphibolite residue. Combining our results and previous studies of the tectonic evolution of the Cathaysia Block, we propose that the crust was thickened to over 40 km by a compressive event occurring during the late Early Cretaceous, which is supported by the observation that there is an angular unconformity between the Upper Cretaceous Series and the early Lower Cretaceous or the Jurassic rocks. After this event, the Cathaysia Block experienced a lithospheric extension and thinning probably driven by the high-angle paleo-Pacific subduction. With the attenuation of lithosphere, the lower crust was heated to partial melting by upwelling asthenospheric materials, resulting in generation of the Lingxi granodiorite and other coeval granitoids in the Cathaysia Block. This study provides new information on the crustal evolution of the Cathaysia Block during the Early Cretaceous. [ABSTRACT FROM AUTHOR]

Modern palms are diverse and widespread in the tropics and subtropics, especially the tropical rainforests. However, most fossil palm records have been reported from regions of relatively higher latitude. In this paper seven species of coryphoid palm from the Eocene Changchang Basin of Hainan Island of South China are reported. These are Sabalites asymmetricus sp. nov., S. robustus sp. nov., S. tenufolius sp. nov., S. szei Guo, S. changchagnensis Guo, Livistona sp., and Amesoneuron sp. According to leaf morphological characteristics, they can be classified as members of the subfamily Coryphoideae. In extant flora of Hainan Island, only three species of Livistona have costapalmate leaves. These palm fossils indicate that, during the Eocene, flora in Hainan Island included a diversity of coryphoid palms, which have some bearings on the reconstruction of the palaeoclimate of South China. [ABSTRACT FROM AUTHOR]

Thermal evolution of source rocks and dynamic sealing evolution of cap rocks are both subjected to tectonic evolution. The marine sequences in South China have experienced superposed structural deformation from multiple tectonic events. To investigate the effectiveness of preservation conditions, it is of great importance to understand the controls of key tectonic events on the dynamic evolution of cap rocks. This paper discusses the controls of Late Jurassic-Early Cretaceous (J-K) tectonic event on source and cap rocks in marine sequences in South China based on the relationships between J-K tectonic event and the burial history types of the marine sequences, the hydrocarbon generation processes of marine source rocks, the sealing evolution of cap rocks, the preservation of hydrocarbon accumulations, and the destruction of paleo-oil pools. The study has the following findings. In the continuously subsiding and deeply buried areas during the J-K period, marine source rocks had been generating hydrocarbons for over a long period of time and hydrocarbon generation ended relatively late. At the same time, the sealing capacity of the overburden cap rocks had been constantly strengthened so that hydrocarbons could be preserved. In the areas which suffered compressional deformation, folding and thrusting, uplifting and denudation in J-K, the burial history was characterized by an early uplifting and the hydrocarbon generation by marine source rocks ended (or suspended) during the J-K period. The sealing capacity of the cap rocks was weakened or even vanished. Thus the conditions for preserving the hydrocarbon accumulations were destroyed. The continuously subsiding and deeply buried areas during the J-K period are the strategic precincts of the petroleum exploration in marine sequences in South China. [ABSTRACT FROM AUTHOR]

Marine red beds occur frequently in China through geological time. Despite their complex environments, the red beds are found in three depositional settings: 1) oceanic, deep water, as in the Upper Cretaceous of southern Tibet; 2) outer shelf, deeper water, as in the Lower-Middle Ordovician of South China; and 3) inner shelf, shallow water, as in the Silurian and Triassic in South China. The Silurian marine red beds are recurrent in the lower Telychian, upper Telychian, and upper Ludlow. This paper is to document the marine nature of the lower Telychian red beds (LRBs) in the Upper Yangtze Region and to discuss the spatial and temporal distribution of the LRBs and their depositional environments. The LRBs are best developed on the north side of the Cathaysian Oldland, which can be interpreted as the source area. It is inferred that they were deposited during a marine regression, characterized by the lack of upwelling, low nutrition and organic productivity with a decrease of biodiversity and a high rate of sedimentation. The iron-rich sediments may have been transported by rivers on the oldland into the Upper Yangtze Sea, as rates of deposition were rapid enough to counteract normal reducing effect around sediment-water interface. The LRBs are different from the off-shore, deeper water red beds of lower Telychian in Avalonia and Baltica and further from the oceanic, deep water red beds of Upper Cretaceous in southern Tibet chiefly in palaeogeographic settings, biotic assemblages and marine environments. [ABSTRACT FROM AUTHOR]

The ages of hydrothermal Hg deposits are difficult to constrain because of the lack of suitable minerals for dating. The South China low-temperature metallogenic domain hosts numerous Hg deposits, including the Jianyan Hg deposit that is composed mainly of cinnabar and calcite. There are two stages of calcite in the deposit: syn-ore calcite (Cal-I) and post-ore/barren calcite (Cal-II). Cal-I is mainly euhedral-subhedral and fine-grained, has homogeneous grey luminescence, and is associated with cinnabar. Subhedral-anhedral Cal-II crosscuts Cal-I and is relatively coarse-grained. The syn-ore Cal-I has high U contents (0.1–1.3 ppm) and U/Pb ratios (up to 4.2), and is thus suitable for U-Pb dating. Using a laser ablation-inductively coupled plasma-mass spectrometer equipped with ion counters, we obtained a U-Pb age of 426.3±5.7 Ma (MSWD=1.5) for Cal-I. This age is interpreted to represent the timing of Hg mineralisation at Jianyan and is similar to ages of 440–400 Ma reported for many carbonate-hosted Pb-Zn and Ba-F deposits in South China. Based on the present results in combination with existing geochemical and geochronological data, we infer that these deposits belong to a Paleozoic Hg-Pb-Zn-Ba-F mineralisation system that was controlled by Caledonian tectonism. [ABSTRACT FROM AUTHOR]

The late Mesozoic antimony (Sb) mineralization belt in South China hosts a large portion of the world's Sb reserves. However, the source and mineralization processes of these Sb deposits remain controversial. Here, we measured mercury (Hg) concentrations and isotopic compositions of stibnite in the Banpo Sb-only and Woxi Sb-polymetallic ore deposits, as well as associated rocks in the Yangtze Block in order to constrain the metal sources and ore formation processes in the South China Sb mineralization belt. Stibnite samples from both deposits exhibit significant enrichment in Hg (4.23–50.6 ppm) and have higher δ202Hg values (−0.47‰ to 2.03‰) than the studied Precambrian basement rocks (−1.42‰ to 0.59‰), Paleozoic sedimentary rocks (−2.40‰ to −0.32‰), and other natural Hg reserves (e.g., marine and continental systems). This indicates that significant mass-dependent fractionation of Hg isotopes occurred during hydrothermal processes. Negative to slightly positive Δ199Hg values of −0.17‰ to 0.02‰ were obtained for stibnite from the studied deposits, similar to values for the Precambrian basement rocks, but different from those of the Paleozoic sedimentary rocks and data previously reported for mantle materials. This suggests that Precambrian basement rocks were the source of Hg and associated metals. Our data and the tectonic evolution of South China indicate that late Mesozoic asthenospheric upwelling, in response to the Paleo-Pacific oceanic slab foundering, generated heat that drove the circulation of fluids in the basement and crustal basinal rocks. These fluids leached Sb, Hg, and other metals from the Precambrian basement rocks and formed the world-class Sb mineralization belt in South China. [ABSTRACT FROM AUTHOR]

South China preserves a rich archaeological record elucidating the evolution of early modern humans during the Late Pleistocene. However, few studies on plant utilization were conducted in this region. We used phytolith analysis from Yahuai Cave, Guangxi, to infer human use of plant resources over the past 30000 years. AMS 14C dating was used to constrain the chronological framework. Results indicate that several economically essential species were present throughout the sequence including Urticineae (cf. Ulmus sp.), which appears in the lower layers of the sequence (Marine Isotope Stage 3 through Heinrich 1); bamboo and palm which appear throughout the sequence, and wild rice which appears in a clear archaeological context dating to 16000 years ago. This is the earliest record of wild rice in South China and a prerequisite for rice domestication. The unique stone tool assemblages, which resemble those in north China as opposed to South China, point to the possibility that humans, seeking refuge from the colder north, brought their tool kit with them and utilized familiar northern taxa. Warmer South China would have served as a refuge for human populations escaping the cold, harsh climate in the north with more ameliorate conditions in the south. [ABSTRACT FROM AUTHOR]

Little is known regarding characteristics and evolution of radiolarian fossils in the early Cambrian due to its rarity and poor preservation. Here we report a new radiolarian fauna from the Cambrian Shuijingtuo Formation corresponding to the Chiungchussuan Stage (Cambrian Series 2) in western Hubei, China. It contains over 300 radiolarian tests and these fossils belong to 4 morphotypes, including Paraantygopora porosa gen.et sp. nov., Braunosphaera sinensis gen.et sp. nov., Tetrasphaera? sp. and incertae spherical radiolarians. In taxonomy, Spumellaria predominates in the fauna and comprises 92% of the total. In shell structure, about 73% of all specimens are similar to the early Ordovician radiolarian fossils, with the shell walls characterized by perforated plate structures. The spherical radiolarians with latticed shells constitute another feature of the early Cambrian radiolarian fauna. The radiolarian fauna reported here contains many fossil specimens and covers different taxonomical taxa. These specimens usually consist of distinctive concentric multi-layers with complex structure. These characteristics indicate that Radiolaria had already thrived during the Cambrian Chiungchussuan Stage (Series 2, Stage 3), which may have occurred synchronously with the explosion and prosperity of macrobiota recorded in the strata deposited in shallower water condition. [ABSTRACT FROM AUTHOR]

This study examines the effectiveness of an ensemble Kalman filter based on the weather research and forecasting model to assimilate Doppler-radar radial-velocity observations for convection-permitting prediction of convection evolution in a high-impact heavy-rainfall event over coastal areas of South China during the pre-summer rainy season. An ensemble of 40 deterministic forecast experiments (40 DADF) with data assimilation (DA) is conducted, in which the DA starts at the same time but lasts for different time spans (up to 2 h) and with different time intervals of 6, 12, 24, and 30 min. The reference experiment is conducted without DA (NODA).To show more clearly the impact of radar DA on mesoscale convective system (MCS) forecasts, two sets of 60-member ensemble experiments (NODA EF and exp37 EF) are performed using the same 60-member perturbed-ensemble initial fields but with the radar DA being conducted every 6 min in the exp37 EF experiments from 0200 to 0400 BST. It is found that the DA experiments generally improve the convection prediction. The 40 DADF experiments can forecast a heavy-rain-producing MCS over land and an MCS over the ocean with high probability, despite slight displacement errors. The exp37 EF improves the probability forecast of inland and offshore MCSs more than does NODA EF. Compared with the experiments using the longer DA time intervals, assimilating the radial-velocity observations at 6-min intervals tends to produce better forecasts. The experiment with the longest DA time span and shortest time interval shows the best performance. However, a shorter DA time interval (e.g., 12 min) or a longer DA time span does not always help. The experiment with the shortest DA time interval and maximum DA window shows the best performance, as it corrects errors in the simulated convection evolution over both the inland and offshore areas. An improved representation of the initial state leads to dynamic and thermodynamic conditions that are more conducive to earlier initiation of the inland MCS and longer maintenance of the offshore MCS. [ABSTRACT FROM AUTHOR]

The genus Paliurus is characterized by its distinctive orbicular-winged fruits and a trilocular (or bilocular) ovary. Macrofossil records suggested this genus was distributed widely in North America, Europe, and Asia during the Paleogene and Neogene, before its present limitation to Eurasia. In this study, we describe some Paliurus fossil winged fruits from the lower part of Youganwo Formation (middle Eocene) and Huangniuling Formation (late Eocene) of the Maoming Basin, South China. These fruits are recognized as Paliurus favonii Unger based on a detailed study on the fossil morphology and cuticle characteristics. This represents the earliest occurrence of Paliurus fossil fruits in eastern Asia, and to date is the world's lowest latitude appearance for this genus. The most ancient records of Paliurus throughout the world are from the middle Eocene of North America and the late Eocene of Japan, leading some researchers to conclude the Paliurus may have originated in North America. Molecular data, however, do not support this hypothesis. The present Paliurus fossil fruits provide new evidence for the origin and phytogeographic history of this genus. [ABSTRACT FROM AUTHOR]

Fossil cyprinids from the upper part of the upper Eocene Youganwo Formation of Maoming, Guangdong, China were first studied in 1957 by Liu, who referred the only specimen to the genus Cyprinus as a new species, C. maomingensis. And this was suggested as one of the earliest records for fossil cyprinids. Unfortunately, this specimen is poorly preserved and reveals no more morphological information than its serrated last unbranched dorsal and anal fin rays. Recently, some new specimens were unearthed from the same locality, where C. maomingensis was discovered. In addition to the serrated dorsal and anal fin rays, these new materials also show that the pattern and shape of their pharyngeal teeth obviously differ from that of Cyprinus but resemble that of Procypris. However, its number of the branched dorsal fin rays and number of vertebrae are much less than that in Procypris. Morphologically, these specimens are closer to Procypris than to Cyprinus. This is the first report of fossil Procypris-like fish, and it implies that Procypris-like fish is an early member of the Tribe Cyprinini sensu stricto ( sensu Yang et al., 2010) and the origin of this group can be traced back at least to the late Eocene. [ABSTRACT FROM AUTHOR]

The Chihsia Formation is one of the four sets of regional marine hydrocarbon source rocks from South China. In the past two decades, detailed geochemical and sedimentological studies have been carried out to investigate its origination, which have demonstrated that the high primary productivity plays a primary role in the deposition of sediments enriched in the organic matter. However, the mechanism of this high productivity and the path of the deposition and burial of the organic matter have always been a mystery. Based on the previous studies on the Shangsi Section in Guangyuan City, Sichuan Province, we proposed that the development of the equatorial upwelling due to the sea level rise is responsible for the relatively high productivity in the Chihsia Formation. The sea waters with high nutrient were transported by the sub-surface currents along the equator. High organic carbon flux was deposited on the deeper shelf, and then decomposed by bacteria, leading to the occurrence of anaerobic respiration. The metabolism of the microorganisms consumed the dissolved oxygen in waters, which was in favor of the preservation of the organic matter. This suggested geobiological model integrating with paleoclimatology, paleoceanography and geomicrobiology will help us to understand the causes of this particular sedimentary sequence. [ABSTRACT FROM AUTHOR]

The well-known Permian Changhsingian calcisponge reef located at Panlongdong section, Xuanhan county, northeastern Sichuan Basin has attracted wide attention. Due to severe dolomitization and poor quality of the fossils, the P-T boundary in this section is difficult to determine. This study, for the first time, recognized six communities in the Upper Permian Changhsingian Changxing Formation through the Lower Triassic Induan Feixianguan Formation of the Panlongdong section. They are Bryozoan- Archaeolithoporella-calcisponge Community, Calcareous green algae-foraminifer-crinoid Community, Microgastropod-foraminifer Community, Ostracod-microgastropod-cystic microbe Community, Ostracod-small brachiopod Community, and Non-calcified cyanobacteria Community. By using community replacement and palaeoenvironmental analysis, for the first time, we set the P-T boundary of the Panlongdong section at the middle of the calcimicrobialite containing cystic microbes. The community replacement sequence in the Panlongdong section is similar to that in other contemporaneous sections in reef areas of South China, indicating universal palaeoenvironmental changes during the Permian-Triassic transition. The results show that: (1) Changhsingian calcisponge reefs in South China generally vanished before the mass extinction and may be related to the large regression in the Late Permian. (2) The Calcareous green algae-foraminifer-crinoid Community replaced reef community and continued till the mass extinction. The mass extinction was probably related to the global sea-level drop. (3) The first aftermath community was dominated by specialized microgastropods, followed by the microbes, and then by the specialized microgastropods and small brachiopods. The succession of the three communities reflected the change in environmental conditions from dysoxic to anoxic and again to dysoxic. (4) In the Early Triassic, the relict community in shallow sea had very low diversity and low abundance, and was dominated by crinoids, gastropods, and bivalves. [ABSTRACT FROM AUTHOR]

The onset timing of the Kwangsian Orogeny might differ among localities across South China. Refined stratigraphic works at different localities are necessary to reveal the details of this likely distinction. Recently, we recollected some graptolite specimens from the Ordovician Shixing and Longtouzhai formations (corresponding to the Longxi Formation of southern Jiangxi Province) at many localities in Guangdong Province. The palaeontological and biostratigraphical studies of these graptolite faunas indicate that the facies change from graptolitic shale to nearshore shallow-water, coarse clastics in Guangdong is slightly earlier than that in southern Jiangxi. This timing difference may imply a northward progression of the Kwangsian Orogeny. Based on the biostratigraphy and palaeontology of the Ordovician in the Zhujiang Basin (western part) and Chiangnan Slope Belt (including western Fujian, eastern Guangdong, northern Guangxi, northern Hunan, northeastern Jiangxi, southern Anhui, and western Zhejiang), the Sandbian to late Katian distribution and replacement of biofacies and lithofacies in the two regions are proposed and discussed, which display distinct features at different stages of the Kwangsian Orogeny. [ABSTRACT FROM AUTHOR]

Based on the well-preserved specimens from the Nanba section in Yiyang, Hunan Province, the definition of the graptolite genus Acrograptus is revised here. The revised Acrograptus is a dichograptid form with stipes subhorizontal to deeply declined, sicula long and slender; th1 budding from the top of the metasicula, proximal development of isograptid type with th1 as the dicalycal theca; asymmetric proximal end resulting from the divergence of th1 and th1 from the sicula at different levels; slender crossing canals composed of extremely slender prothecae of th11 and th1. According to the revised definition, Acrograptus is assigned to the subfamily Sigmagraptinae of the family Dichograptidae, including six species, i.e., A. affinis (Nicholson), A. filiformis (Tullberg), A. gracilis (Törnquist), A. nicholsoni (Lapworth), A. pusillus (Tullberg), and A. saukros (Ni). During the Early-Middle Ordovician, these six species were widely distributed in South China, especially in the Upper Yangtze Region as well as the central and eastern Jiangnan Region. This study further indicates that Acrograptus first appeared in a deep-water setting on the Jiangnan Slope in South China during early Floian ( Tetragraptus approximatus Biozone), and subsequently expanded into the shallow-water region on the Yangtze Platform due to a remarkable dispersion event in middle Floian ( Pendeograptus fruticosus Biozone). It is here indicated that the dispersal of Acrograptus may be directly controlled by the large-scale transgression event occurring in middle Floian. [ABSTRACT FROM AUTHOR]

Fossil reproductive structure from the Eocene of the Changchang Basin (Hainan Island, South China) is recognized as Chaneya hainanensis sp. nov. This new species is characterized by persistent corolla of five obovate petals with three subparallel primary venation linked by arching secondary veins, circular central disk bearing two orbicular ovaries or fruit bodies. This discovery confirms the presence of the extinct fruit genus Chaneya in low-latitude tropical area, providing significant fossil evidence for investigating the origin, migration, and phytogeography of this genus and discussing the Tertiary floristic exchanges among North America, eastern Asia, and Europe. Considering the distribution of this genus and its extant relatives and the climate changes during the Cenozoic, we hypothesize that Chaneya was a widespread tropical or subtropical taxon, but, with climate cooling, became extinct in northern latitudes and evolved into Picrasma (Simaroubaceae) and Rutaceae mainly in modern tropics and subtropics. [ABSTRACT FROM AUTHOR]

The water contents of nominally anhydrous clinopyroxene (cpx), orthopyroxene (opx) and olivine (ol) in peridotite xenoliths hosted by Cenozoic basalts from Yingfengling, Zhangchouchun, Fujitian and Lindi, South China, were measured by Micro-FTIR. All cpx and opx grains contained a certain amount of water, which was indicated by the presence of hydroxyls in the crystal structure. The water contents (HO, ppm) of cpx and opx from peridotite xenoliths of the study areas were 293-981, 183-752, 73-586 and 51-423 ppm, and 82-471, 74-571, 53-170 and 9-135 ppm, respectively. No prominent OH absorption bands were detected for any ol grains, indicating that the water contents were below the detection limit (approximately 2 ppm). The entire rock contents recalculated according to mineral volume proportions were 49-163, 48-168, 21-111 and 8-40 ppm, respectively. Combined with previously reported data describing the water contents of peridotite xenoliths worldwide, the results presented here suggest that water distribution in the continental lithospheric mantle is spatially heterogeneous at a global scale. The lithospheric mantle of South China is much richer in water than that of the North China Craton, and is close to that typical of off-craton localities, such as the Basin and Range Province, and Massif Central. [ABSTRACT FROM AUTHOR]