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Meng H.-H.,CAS Xishuangbanna Tropical Botanical Garden | Meng H.-H.,University of Chinese Academy of Sciences | Jacques F.M.B.,CAS Xishuangbanna Tropical Botanical Garden | Su T.,CAS Xishuangbanna Tropical Botanical Garden | And 5 more authors.
BMC Evolutionary Biology | Year: 2014

Background: Given that most species that have ever existed on earth are extinct, it stands to reason that the evolutionary history can be better understood with fossil taxa. Bauhinia is a typical genus of pantropical intercontinental disjunction among the Asian, African, and American continents. Geographic distribution patterns are better recognized when fossil records and molecular sequences are combined in the analyses. Here, we describe a new macrofossil species of Bauhinia from the Upper Miocene Xiaolongtan Formation in Wenshan County, Southeast Yunnan, China, and elucidate the biogeographic significance through the analyses of molecules and fossils. Results: Morphometric analysis demonstrates that the leaf shapes of B. acuminata, B. championii, B. chalcophylla, B. purpurea, and B. podopetala closely resemble the leaf shapes of the new finding fossil. Phylogenetic relationships among the Bauhinia species were reconstructed using maximum parsimony and Bayesian inference, which inferred that species in Bauhinia species are well-resolved into three main groups. Divergence times were estimated by the Bayesian Markov chain Monte Carlo (MCMC) method under a relaxed clock, and inferred that the stem diversification time of Bauhinia was ca. 62.7 Ma. The Asian lineage first diverged at ca. 59.8 Ma, followed by divergence of the Africa lineage starting during the late Eocene, whereas that of the neotropical lineage starting during the middle Miocene. Conclusions: Hypotheses relying on vicariance or continental history to explain pantropical disjunct distributions are dismissed because they require mostly Palaeogene and older tectonic events. We suggest that Bauhinia originated in the middle Paleocene in Laurasia, probably in Asia, implying a possible Tethys Seaway origin or an "Out of Tropical Asia", and dispersal of legumes. Its present pantropical disjunction resulted from disruption of the boreotropical flora by climatic cooling after the Paleocene-Eocene Thermal Maximum (PETM). North Atlantic land bridges (NALB) seem the most plausible route for migration of Bauhinia from Asia to America; and additional aspects of the Bauhinia species distribution are explained by migration and long distance dispersal (LDD) from Eurasia to the African and American continents. © 2014 Meng et al.; licensee BioMed Central Ltd.


PubMed | CAS Xishuangbanna Tropical Botanical Garden, Zhejiang Institute of Geological Survey, CAS Kunming Institute of Botany and Kunming University of Science and Technology
Type: | Journal: BMC evolutionary biology | Year: 2015

Given that most species that have ever existed on earth are extinct, it stands to reason that the evolutionary history can be better understood with fossil taxa. Bauhinia is a typical genus of pantropical intercontinental disjunction among the Asian, African, and American continents. Geographic distribution patterns are better recognized when fossil records and molecular sequences are combined in the analyses. Here, we describe a new macrofossil species of Bauhinia from the Upper Miocene Xiaolongtan Formation in Wenshan County, Southeast Yunnan, China, and elucidate the biogeographic significance through the analyses of molecules and fossils.Morphometric analysis demonstrates that the leaf shapes of B. acuminata, B. championii, B. chalcophylla, B. purpurea, and B. podopetala closely resemble the leaf shapes of the new finding fossil. Phylogenetic relationships among the Bauhinia species were reconstructed using maximum parsimony and Bayesian inference, which inferred that species in Bauhinia species are well-resolved into three main groups. Divergence times were estimated by the Bayesian Markov chain Monte Carlo (MCMC) method under a relaxed clock, and inferred that the stem diversification time of Bauhinia was ca. 62.7 Ma. The Asian lineage first diverged at ca. 59.8 Ma, followed by divergence of the Africa lineage starting during the late Eocene, whereas that of the neotropical lineage starting during the middle Miocene.Hypotheses relying on vicariance or continental history to explain pantropical disjunct distributions are dismissed because they require mostly Palaeogene and older tectonic events. We suggest that Bauhinia originated in the middle Paleocene in Laurasia, probably in Asia, implying a possible Tethys Seaway origin or an Out of Tropical Asia, and dispersal of legumes. Its present pantropical disjunction resulted from disruption of the boreotropical flora by climatic cooling after the Paleocene-Eocene Thermal Maximum (PETM). North Atlantic land bridges (NALB) seem the most plausible route for migration of Bauhinia from Asia to America; and additional aspects of the Bauhinia species distribution are explained by migration and long distance dispersal (LDD) from Eurasia to the African and American continents.


Rong J.Y.,CAS Nanjing Institute of Geology and Palaeontology | Zhan R.B.,CAS Nanjing Institute of Geology and Palaeontology | Xu H.G.,Zhejiang Institute of Geological Survey | Huang B.,CAS Nanjing Institute of Geology and Palaeontology | Yu G.H.,Zhejiang Institute of Geological Survey
Science China Earth Sciences | Year: 2010

Located northwest of the Jiangshan-Shaoxing Fault Zone, western and northwestern Zhejiang and northeastern Jiangxi provinces experienced major changes in bio- and litho-facies and paleogeography through the Ordovician-Silurian transition (late Katian, Hirnantian, and early Rhuddanian), as manifested by stratigraphic, paleontologic and synecologic records. Three geographic units under consideration are South, Central, and North areas. The western margin of the South area was occupied by the Huaiyu Mountains, whereas the other two parts were covered by the Zhe-Gan Sea during late Katian (Late Ordovician) time. In the early stage of the Changwu Formation deposition (late Katian), the sea was deepening northeastward, but with shallower conditions in the southwest and deeper conditions in the northeast. During mid to late stages of Changwu Formation deposition (latest Katian), the sea became much shallower and the sea bottom was uplifted substantially, which occurred somewhat prior to the global trend. During the Hirnantian (latest Ordovician) and early Rhuddanian (earliest Silurian), the study region became a shallow bay under expansion of the Cathaysian Oldland. There occurred a major drop of sea level and great changes in benthic biota with the occurrence of many new immigrants through the Ordovician-Silurian transition, which are closely related to a unique regional orogeny. The Yangtze and Cathaysian blocks may have amalgamated within the South China Paleoplate during this interval to cause the continuous uplifting and northwestward expansion of the Cathaysian Oldland. © Science China Press and Springer-Verlag Berlin Heidelberg 2010.


Li Z.,Zhejiang University | Zhou J.,Zhejiang University | Mao J.,Nanjing Institute of Geology and Mineral Resources | Santosh M.,China University of Geosciences | And 7 more authors.
Lithos | Year: 2013

Granitoids (175-80Ma) representing a prominent Yanshanian (Jurassic to Cretaceous) magmatic event in South China widely intrude the Precambrian crystalline basement and Paleozoic strata. Here we report zircon U-Pb age data, geochemical characteristics and Sr-Nd isotopes of the Late Jurassic and Early Cretaceous granitoids from the northwestern Zhejiang Province (ZXB) of southeastern China. Our results reveal two distinct episodes for the Yanshanian magmatism. The Jiemeng and Datongkeng granodiorites formed at 148.6±1.1Ma, whereas the Huangshitan, Jiuligang and Ruhong aluminous A-type granites were generated between 129.0±0.6Ma and 126.1±1.1Ma. The two magmatic phases represent a tectonic transition from an active continental margin to post-orogenic setting during the Late Jurassic (ca. 150Ma) to Early Cretaceous (ca. 128Ma). Geochemically, these intrusions are granodioritic to granitic in composition and show an affinity of S-type and A-type granitoids, respectively. The S-type granodiorites of Jiemeng and Datongkeng are characterized by moderate SiO2 (65.0-69.6wt.%), high K2O+Na2O (5.0-7.6wt.%), K2O/Na2O (1.2-1.5), Zr (31-109ppm), Sr (71-190ppm) and high field strength elements, low to intermediate Mg#, and moderate Nb depletion. The A-type granites of Huangshitan, Jiuligang and Ruhong are characterized by high SiO2 (72.7-77.2wt.%), K2O+Na2O (6.9-8.8wt.%), K2O/Na2O (1.3-2.1), FeT/(FeT+Mg), Ga (17-29ppm, >20ppm commonly), Zr (96-197ppm) and Sr (8-45ppm) with slight Nb depletion. The S-type granodiorites have higher Mg#, A/NK, Sr, Sr/Ba, Sr/Y, (La/Yb)N, and LREE/HREE, and lower SiO2, K2O+Na2O, Ga and Zr with weak negative Eu anomalies compared to those of the A-type granites with negative Eu anomalies. All these rocks show Y/Nb ratios >1.2, high initial 87Sr/86Sr (ISr) ratios and low εNd(t), and are depleted in Nb, Ti and Sr, indicating crustal origin with subduction zone signatures. We suggested that the ZXB S-type granitic bodies might have been derived from the Mesoproterozoic metamorphic basement rocks through partial melting induced by mantle-derived magma, followed by limited fractional crystallization. The ZXB aluminous A-type granites were also derived from a similar magma source but underwent fractional crystallization at higher crustal levels. The A-type granites in the ZXB correlate with a post-orogenic tectonic setting. A geological comparison between ZXB and adjacent areas indicates that the geochemical features of the ZXB A-type granites are comparable with the Baijuhuajian A-type granites and also the adjacent areas A-type granites, but are distinct from the Late Cretaceous A-type granites (105-90Ma) distributed along the southeastern coastal area of South China. We correlate the formation of the ZXB S-type granodiorites to inland compression associated with the subduction and collision of the paleo-Pacific plate in the Late Jurassic (170-145Ma). In contrast, the A-type granites formed under a post-orogenic setting during the Early Cretaceous period (145-120Ma) resulting from lithospheric thinning and continent extension accompanied by slab roll-back of the paleo-Pacific plate following the subduction-collision event. © 2013 Elsevier B.V.


Ling M.-X.,CAS Guangzhou Institute of Geochemistry | Zhang H.,Northwest University, China | Li H.,CAS Guangzhou Institute of Geochemistry | Liu Y.-L.,CAS Guangzhou Institute of Geochemistry | And 5 more authors.
Lithos | Year: 2014

Granitoids near the Bayan Obo giant rare earth element (REE) deposit at the north margin of the North China Craton (NCC), the world's largest light REE (LREE) deposit, have been taken by some authors as the key factors that controlled the mineralization. In contrast, others proposed that the REE deposit has been partially destructed by these granitoids. Here we report systematic studies on geochronology and geochemical characteristics of granitoids of different distances from the orebodies, to investigate the genesis and their relationship to the giant Bayan Obo deposit. Granitoids studied here, including granites and quartz monzonites, are peraluminous with A/CNK=0.99-1.11, LREE enriched and heavy REE (HREE) depleted, with variable REE concentrations (total REE=54-330ppm) and large negative Eu anomaly (δEu=0.19-0.70). The REE patterns are distinct from those of ore-bearing dolomites. Some samples have slightly higher LREE concentrations, which may have been contaminated by the orebodies during intrusion. Trace elements of the granitoids are characterized by positive Pb anomaly, strong negative Ti anomaly and Nb, Ta and Sr anomalies. The granites exhibit negative Ba anomaly. The granitoids plot within the post-collision granite field in the Pearce diagram, which is consistent with the tectonic regime. The quartz monzonites and one granite have A-type granite characteristics and belong to the A2 subgroup. Zircons in these granitoids have high Th/U values, which are typical for magmatic zircons. High precision U-Pb dating for these zircons by secondary ion mass spectrometry (SIMS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) yields Permian-Triassic 206Pb/238U ages ranging from 243.2 to 293.8Ma. The formation of the granitoids is >55Ma later than the latest ore forming age. The zircons have low La concentrations (0.02-12ppm), high (Sm/La)N (0.8-685) and Ce/Ce* (1.4-80). The Ti-in-zircon temperature of the granitoids ranges from 590 to 770°C. All these evidences suggest that the granitoids have no contribution to the formation of the Bayan Obo deposit. Granitoids that are close to the orebodies had limited interaction with it and gained some LREE-enriched characteristics during magmatisms. Nevertheless, their effects to the orebodies are subtle. All the granitoids formed in a post-collisional tectonic regime at convergent margins, which is consistent with plate subduction during the closure of the Palaeo-Asian Ocean, which started in the Neoproterozoic and lasted until the Carboniferous/Permian. © 2014 Elsevier B.V.


Ding X.,CAS Guangzhou Institute of Geochemistry | Hu Y.,Zhejiang Institute of Geological Survey | Zhang H.,CAS Guangzhou Institute of Geochemistry | Zhang H.,Northwest University, China | And 3 more authors.
Journal of Geology | Year: 2013

Mobilities and fractionations of high-field-strength elements, especially Nb and Ta within a subducting slab, are important for deciphering the formation of the continental crust (CC). Here we report geochemical results on an epidote garnet amphibolite facies metagabbro body in the Tongbai-Dabie orogenic belt, central China. Our samples were hydrated during prograde metamorphism of the Triassic plate subduction. Major minerals such as amphibole, garnet, rutile, and ilmenite and garnet amphibolite bulk rocks show varied and overall lower Nb/Ta and/or Zr/Hf ratios than the continental crust. Magma differentiation might have contributed to variations of Zr/Hf but not those of Nb/Ta, suggesting major Nb/Ta fractionations during plate subduction. LA-ICPMS in situ trace element analyses of amphibole and especially rutile grains exhibit obvious chemical zonations. Typically, the rutile cores are usually small with higher Nb and Ta concentrations and lower Nb/Ta ratios compared to the thick rims. Chemical and fabric characteristics of the zonations may be explained by diverse external fluid activities: the gabbro first absorbed low Nb/Ta fluids that were released during blueschist to amphibolite transformation in deeper portions of the subducting slab, followed by acquiring external fluids with elevated Nb/Ta released during amphibolite to eclogite transformation. Our results imply that fluids with low Nb/Ta released during blueschist to amphibolite transformation can be transferred to cold regions within a subducted plate and also to the mantle wedge through fluid-rock reaction. Such regions are more easily melted during further subduction, especially in the early history of the earth, providing a plausible explanation for the low Nb/Ta in the CC. © 2013 by The University of Chicago.


Gu M.-G.,Hubei University | Gu M.-G.,Zhejiang Institute of Geological Survey | Feng L.-X.,Zhejiang Institute of Geological Survey | Hu Y.-H.,Zhejiang Institute of Geological Survey | And 2 more authors.
Geological Bulletin of China | Year: 2011

The LA-ICP-MS U-Pb dating of zircons was carried out for two representative rock samples from Guangshan and Zhaxi plutons, which are closely related to mineralization of the Lizhu iron ore deposit. Based on the obtained results and regional chronologic data of mineralization, this paper has dealt with the mineralization age of the Lizhu iron ore deposit. The samples from Zhaxi pluton yielded the age of 150.1±2.6Ma, which is interpreted as its petrogenic age, and the sample from Guangshan pluton shows a number of magmatic events, with the main petrogenic age 147.2±1.7Ma, suggesting that both plutons belong to Yanshannian granitoids. Geological features of the Lizhu iron ore district show that mineralization of the Lizhu iron ore deposit was closely related to the magmatic hydrothermal event of Guangshan and Zhaxi plutons. In other words, the formation age of Guangshan and Zhaxi plutons represents the ore-forming age of the Lizhu iron ore deposit, i.e., Lizhu iron ore bodies were formed in Jurassic (~150Ma). Precise mineralization age of the Lizhu iron ore deposit plays a guiding role in search for the same type of ore deposits in adjacent areas.


Zeng J.-N.,Wuhan University | Li J.-W.,Wuhan University | Chen J.-H.,Wuhan University | Chen J.-H.,Zhejiang Institute of Geological Survey | Lu J.-P.,Wuhan University
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | Year: 2013

The SHRIMP zircon U-Pb dating of granodiorite-porphyry, the main rock type of Anjishan rock mass yields the age of 106.9±0.9 Ma, as the formation age of the Anjishan rock mass, which shows that the Anjishan rock mass formed in the late Early Cretaceous. Anjishan rock mass is younger than the high-K calc-alkaline intermediate-acidic intrusive rocks in Tongling and other districts and it illustrates that the intermediate-acidic intrusive rocks in Ningzhen District belongs to another diagenetic event in the middle to lower Yangtze metallogenic belt's Mesozoic large magmatism. The Ningzhen District's Cu-polymetallic mineralization is closely related with the 107 Ma calc-alkaline intermediate-acidic magmatism in time, space and origin. The petrogenesis- mineralization has been a continuous process in this district. The geodynamics background of the Ningzhen District's calc-alkaline intermediate-acidic magmatism corresponds to the Mesozoic lithospheric delamination thinning event in Eastern China. It demonstrates that the middle to lower Yangtze lithosphere delamination began at about 130 Ma, and lasted to 107 Ma or later.


Yu Y.-W.,Zhejiang Institute of Geological Survey | Jin X.-S.,Zhejiang Museum of Natural History | Wu X.-L.,Zhejiang Institute of Geological Survey | Zhang Z.-F.,Zhejiang Institute of Geological Survey
Geology in China | Year: 2010

Dinosaur and egg fossils were found in 12 Upper Cretaceous basins of Zhejiang Province, and in some basins both dinosaur and egg fossils were observed. Except for Jinqu Basin where dinosaur fossils were found in Zhongdai Formation of Lower Qujiang Group, dinosaurs and egg fossils in all other basins were exclusively produced in the middle and upper strata, i.e., Chaochuang and Fangyan Formations of Yongkang Group, Jinhua and Quxian Formations of Qujiang Group, and Liangtoutang and Chichengshan Formations of Tiantai Group. According to characteristics of biostratigraphy, isotopic data (101 -90Ma) and positive polarity paleomagnetism, the authors consider that the age of some fossil eggs in Zhejiang is Late Cretaceous, whereas the age of Faveoloolithidae may be the end of Cretaceous. Researches on dinosaurs and dinosaur egg fossils of Zhejiang Province are of great significance in the subdivision of die Upper Cretaceous strata in Zhejiang Province.


Wang X.-L.,Nanjing University | Shu L.-S.,Nanjing University | Xing G.-F.,Nanjing Institute of Geology and Mineral Resources | Zhou J.-C.,Nanjing University | And 4 more authors.
Precambrian Research | Year: 2012

We present a systematic geochronological and geochemical study on ca 800-760Ma volcanic rocks in the eastern part of the Jiangnan orogen. The Xucun composite dykes are dated at ca 805Ma; the mafic components have OIB-like trace-element patterns and positive anomalies in Zr and Hf. The least-contaminated sample has relatively depleted Nd isotopic features, suggesting the Xucun mafic dykes may have been generated from the partial melting of OIB-like asthenosphere with later crustal contamination. The Xucun felsic dykes have decoupled Nd-Hf isotopes, and the Hf-isotope compositions of zircons indicate that the dykes may be derived from the partial melting of the early Neoproterozoic juvenile crustal materials, with minor incorporation of Paleoproterozoic crustal components. The ca 800-790Ma Shangshu volcanics include two compositional series: calc-alkaline and tholeiitic. The Shangshu calc-alkaline volcanics in the Minjiawu area have low abundances of LILE, HFSE and high Na2O contents and Sr/Y ratios, similar to adakitic rocks. The evident arc-like geochemical features and radiogenic Nd isotopes (εNd(t) values of +3.7 to +4.8) suggest that these rocks may have been generated from the partial melting of juvenile lithospheric mantle metasomatized by Na-rich melts released from the subducted slab. The tholeiitic mafic rocks from the Shangshu bimodal volcanics represent two different magma sources. The partial melting of metasomatized lithospheric mantle led to the formation of arc-like basalts with low TiO2 contents, negative anomalies in Zr and Hf, and high values of Mg# and εNd(t) (+6.2), whereas the partial melting of asthenospheric mantle generated volcanic rocks with high TiO2 contents and low positive εNd(t) (+1.4 to +2.7), without negative anomalies of Nb, Ta, Zr and Hf. The Shangshu felsic rocks were formed by the reworking of early Neoproterozoic juvenile arc crustal materials. The ca 760Ma mafic rocks from the Puling bimodal volcanics generally have low TiO2 contents (<0.9wt%), nearly flat REE distributions and arc-like trace-element patterns. They may have been generated from the high-degree partial melting of metasomatized lithospheric mantle. One sample has a high TiO2 content (2.41wt%) and high εNd(t) (+6.2), with overall OIB-like trace-element patterns, implying the local partial melting of asthenospheric mantle. The occurrence of significant volumes of bimodal volcanics in the eastern part of the Jiangnan orogen suggests an extensional setting in the period ca 800-760Ma. The evident partial melting of newly-metasomatized lithospheric mantle and subordinate partial melting of asthenosphere suggest that post-orogenic extension shortly after the Neoproterozoic orogenesis may be a better explanation for the genesis of the mid-Neoproterozoic magmatic rocks in the eastern part of the Jiangnan orogen. Post-orogenic extension may be diachronous along the whole orogenic belt, and probably has no direct relationship with the Rodinia rifting event. A more detailed model is presented to illustrate the evolution of the eastern part of the Jiangnan orogen. © 2011 Elsevier B.V.

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