The uplift of the Ailao Shan-Diancang Shan （ASDS） along the Ailao Shan-Red River （ASRR） shear zone is an important geological event in the southeastern margin of Qinghai-Tibet Plateau tectonic domain in the Late C...The uplift of the Ailao Shan-Diancang Shan （ASDS） along the Ailao Shan-Red River （ASRR） shear zone is an important geological event in the southeastern margin of Qinghai-Tibet Plateau tectonic domain in the Late Cenozoic, and it preserves important information on the structures, exhumationai history and tectonic evolution of the ASRR shear zone. The uplift structural mode and uplift timing of the ASDS is currently an important scientific topic for understanding the ASDS formation and late stage movements and evolution of the ASRR shear zone. The formation of the ASDS has been widely considered to be the consequence of the strike-slip movements of the ASRR shear zone. However, the shaping of geomorphic units is generally direct results of the latest tectonic activities. In this study, we investigated the timing and uplift structural mechanism of the ASDS and provided the following lines of supportive evidence. Firstly, the primary tectonic foliation of the ASDS shows significant characteristic variations, with steeply dipping tectonic foliation developed on the east side of the ASDS and the relatively horizontal foliation on the west side. Secondly, from northeast to southwest direction, the deformation and metamorphism gradually weakened and this zone can be further divided into three different metamorphic degree belts. Thirdly, the contact relationship between the ASDS and the Chuxiong basin-Erhai lake is a normal fault contact which can be found on the east side of the ASDS. 40^Ar/^39 Argeochronology suggests that the Diancang Shan had experienced a fast cooling event during 3-4 Ma. The apatite fission track testing method gives the age of 6.6-10.7 Ma in the Diancang Shan and 4.6-8.4 Ma in the Ailao Shan, respectively. Therefore the uplift of the ASDS can be explained by tilted block mode in which the east side was uplifted much higher than the west side, and it is not main reason of the shearing movements of the ASRR shear zone. The most recent uplift stages of the ASDS happened in the Pliocene （3-4 Ma） and Late Miocene （6-10 Ma）.展开更多
Calcareous nannofossils were observed to reconstruct the surface water conditions during late Pliocene climate transition (2.55 to 2.88 Ma) from the southern Gardar Drift, in the subpolar North Atlantic IODP Site U131...Calcareous nannofossils were observed to reconstruct the surface water conditions during late Pliocene climate transition (2.55 to 2.88 Ma) from the southern Gardar Drift, in the subpolar North Atlantic IODP Site U1314 (56°21.9’1N, 27°53.3’W). A total of 24 species from 14 genera were identified by polarizing microscope observation. The coccolith assemblages are dominated by species belonging to genus Reticulofenestra with different (size-defined) morphotype. Hence, changes in paleoceanographic condition are shown by the size variation of Reticulofenstraspecimens. Before ~2.76 Ma, the studied interval is characterized by the presence of an abundant larger Reticulofenstra group. It indicates warm oligotrophic and stable surface waters. At ~2.76 Ma the abundance of large Reticulofenstra decreased abruptly and alternated with small Reticulofenstra, suggesting collapse of sea surface stability with strong mixing condition. This event coeval with the final closure of the Central American Seaway (CAS) and the onset of intensified North Hemisphere Glaciation (NHG). Subsequently, the size variation of Reticulofenestra specimens exhibits a sequential pattern that is somewhere consistent with the interglacial-glacial cycle. The pattern begins with a gradual increase in size upward during interglacial suggesting warm oligotrophic and stable condition, and ends with an abrupt decrease in coccolith size during glacial suggesting eutrophic or strong mixing condition and destabilized sea surface waters.展开更多
The palaeodiversity of flowering plants in Yunnan has been extensively interpreted from both a molecular and fossil perspective. However, for cryptogamic plants such as ferns, the palaeodiversity remains poorly known....The palaeodiversity of flowering plants in Yunnan has been extensively interpreted from both a molecular and fossil perspective. However, for cryptogamic plants such as ferns, the palaeodiversity remains poorly known. In this study, we describe a new ferny fossil taxon, Drynaria lanpingensis sp. nov. Huang,Su et Zhou(Polypodiaceae), from the late Pliocene of northwestern Yunnan based on fragmentary frond and pinna with in situ spores. The frond is pinnatifid and the pinnae are entirely margined. The sori are arranged in one row on each side of the primary vein. The spores have a semicircular to bean-shaped equatorial view and a tuberculate surface. Taken together with previously described fossils, there are now representatives of three known fossil taxa of Drynaria from the late Pliocene of western Yunnan.These finds suggest that Drynaria diversity was considerable in the region at that time. As Drynaria is a shade-tolerant plant, growing preferably in wet conditions in the understory of forests, its extensive existence may indicate forest vegetation and humid climates in western Yunnan during the late Pliocene.This is in line with results from floristic investigations and palaeoclimatic reconstructions based on fossil floras.展开更多
The equatorial Pacific underwent a significant climate transition during the late Pliocene, which is characterized by cooling of global sea surface temperatures (SSTs) and formation of a marked SST gradient between th...The equatorial Pacific underwent a significant climate transition during the late Pliocene, which is characterized by cooling of global sea surface temperatures (SSTs) and formation of a marked SST gradient between the eastern and western equatorial Pacific. Moreover, this transition was nearly synchronous with the late Pliocene Northern Hemisphere glaciation. Probing the relationship among solar insolation, low and high latitude processes is the key to unravel the mechanism of this climate transition. A series of statistical methods were used in this study to analyze the orbital components of the equatorial Pacific SST and global ice volume records for the past 5 Ma. We found that integrated solar insolation rather than the monthly mean insolation is the primary external forcing of the late Pliocene climate transition, and that on orbital time scale the SSTs of the eastern and western equatorial Pacific display consistent change rather than a "seesaw" pattern. Changes of Earth’s orbital configuration have been responsible for this climate transition whereas the feedback effects of atmospheric CO2 concentration have further cooled the global climate since the early Cenozoic.展开更多
A number of fossil leaves of the Lauraceae were collected from Tuantian flora of the late Pliocene strata in Yunnan, China. They have a whole leaf shape and well-preserved cuticles. In this paper, features of the arch...A number of fossil leaves of the Lauraceae were collected from Tuantian flora of the late Pliocene strata in Yunnan, China. They have a whole leaf shape and well-preserved cuticles. In this paper, features of the architecture and epidermis of three species of the Lauraceae family with ternate venation are reported. Results of the comparison between the venation characteristics of Lauraceae fossils from four fossil floras in the world and those of extant Lauraceae in China suggest that the proportion of Lauraceae species with ternate venation is increasing. The proportion has risen from 10% in the Eocene to 12.5% in the late Pliocene in China, whereas the proportion in the modern era is 21%. Moreover, the proportion of Australian floras with ternate venation has rised from 8.3% to 10% between the Eocene and the Miocene. Because of the effect of the global drought during the Cenozoic era, we suggested that species with ternate venation in Lauraceae have become increasingly prevalent between the Eocene era and the present day in China. Data on Nerriga flora and Maarlake flora since the Eocene era in the Southern Hemisphere show the same trend. While features of the leaf architecture and epidermis of Lindera acuminatissima differ in details. They all have similar identification characteristics with regard to basal eucamptodromous venation, interior 2° present, minor 2° simple brochidodromous, anticlinal walls, no surface ornamentation, lip-like guard cells, outer stomatal ledge plain or dimness, and paracytic stomatal aperture. These differences are also present in extant species. Compared with Lindera tonkinensis, the nearest living relative(NLR) of L. acuminatissima shows that these differences are relevant to the growth, position, and development of leaves. Leaf-type classification statistics of L. acuminatissima indicate that when all fossil leaves are taken into consideration, A-type leaves account for 24%, B-type leaves make up 56%, and C-typy leaves account for 20%. Comparing the above result with that of NLRs, A-type leaves are generally immature spires and cannot be preserved easily, B-type leaves are regular mature leaves and fossilize more easil, and C-type leaves are usually old leaves occurring at the bottom, broken, ill and consumed by worms.展开更多
The vertebrate fossil record from the Balearic Islands(western Mediterranean)has improved considerably over the past decade,especially in Mallorca and Menorca.In Menorca,the Pliocene terrestrial fauna was updated by t...The vertebrate fossil record from the Balearic Islands(western Mediterranean)has improved considerably over the past decade,especially in Mallorca and Menorca.In Menorca,the Pliocene terrestrial fauna was updated by the discovery and description of the large-sized leporid Nuralagus,several reptiles and an amphibian.In Mal-lorca,paleontological exploration yielded 2 deposits with a Late Miocene/Early Pliocene chronology,Calóden Rafelino(CdR)and Na Burguesa-1(NB-1).So far,4 new mammalian taxa and 2 new reptiles have been iden-tified for the CdR deposit,whereas the faunal assemblage from the recently discovered deposit(Apr 2012)of NB-1 is currently composed of,at least,6 terrestrial mammals,8 reptiles and an amphibian.Its faunal composi-tion and some primitive characteristics of the obtained taxa suggest that the chronology of this deposit is slight-ly earlier than the CdR.The terrestrial vertebrates recorded in these 2 Mallorcan deposits are changing the view of the paleofaunal assemblage previously known for the Plio-Pleistocene of the island.Morphological charac-teristics displayed by some of the taxa suggest that these faunas would be at the beginning of an isolated evo-lution.In this paper we present a preliminary report on the fossils recovered from the NB-1 deposit,as well as some unpublished data from CdR,and we analyze the whole fauna from both Mallorcan deposits,focusing on taxonomical and paleobiogeographical aspects.展开更多
基金supported by the National Natural Foundation of China(No.40872149,40472100 and 40930419)
文摘The uplift of the Ailao Shan-Diancang Shan （ASDS） along the Ailao Shan-Red River （ASRR） shear zone is an important geological event in the southeastern margin of Qinghai-Tibet Plateau tectonic domain in the Late Cenozoic, and it preserves important information on the structures, exhumationai history and tectonic evolution of the ASRR shear zone. The uplift structural mode and uplift timing of the ASDS is currently an important scientific topic for understanding the ASDS formation and late stage movements and evolution of the ASRR shear zone. The formation of the ASDS has been widely considered to be the consequence of the strike-slip movements of the ASRR shear zone. However, the shaping of geomorphic units is generally direct results of the latest tectonic activities. In this study, we investigated the timing and uplift structural mechanism of the ASDS and provided the following lines of supportive evidence. Firstly, the primary tectonic foliation of the ASDS shows significant characteristic variations, with steeply dipping tectonic foliation developed on the east side of the ASDS and the relatively horizontal foliation on the west side. Secondly, from northeast to southwest direction, the deformation and metamorphism gradually weakened and this zone can be further divided into three different metamorphic degree belts. Thirdly, the contact relationship between the ASDS and the Chuxiong basin-Erhai lake is a normal fault contact which can be found on the east side of the ASDS. 40^Ar/^39 Argeochronology suggests that the Diancang Shan had experienced a fast cooling event during 3-4 Ma. The apatite fission track testing method gives the age of 6.6-10.7 Ma in the Diancang Shan and 4.6-8.4 Ma in the Ailao Shan, respectively. Therefore the uplift of the ASDS can be explained by tilted block mode in which the east side was uplifted much higher than the west side, and it is not main reason of the shearing movements of the ASRR shear zone. The most recent uplift stages of the ASDS happened in the Pliocene （3-4 Ma） and Late Miocene （6-10 Ma）.
文摘Calcareous nannofossils were observed to reconstruct the surface water conditions during late Pliocene climate transition (2.55 to 2.88 Ma) from the southern Gardar Drift, in the subpolar North Atlantic IODP Site U1314 (56°21.9’1N, 27°53.3’W). A total of 24 species from 14 genera were identified by polarizing microscope observation. The coccolith assemblages are dominated by species belonging to genus Reticulofenestra with different (size-defined) morphotype. Hence, changes in paleoceanographic condition are shown by the size variation of Reticulofenstraspecimens. Before ~2.76 Ma, the studied interval is characterized by the presence of an abundant larger Reticulofenstra group. It indicates warm oligotrophic and stable surface waters. At ~2.76 Ma the abundance of large Reticulofenstra decreased abruptly and alternated with small Reticulofenstra, suggesting collapse of sea surface stability with strong mixing condition. This event coeval with the final closure of the Central American Seaway (CAS) and the onset of intensified North Hemisphere Glaciation (NHG). Subsequently, the size variation of Reticulofenestra specimens exhibits a sequential pattern that is somewhere consistent with the interglacial-glacial cycle. The pattern begins with a gradual increase in size upward during interglacial suggesting warm oligotrophic and stable condition, and ends with an abrupt decrease in coccolith size during glacial suggesting eutrophic or strong mixing condition and destabilized sea surface waters.
基金supported by the National Natural Science Foundation of China (31300187,U1502231)the Major Program of National Science Foundation of China (31590823)
文摘The palaeodiversity of flowering plants in Yunnan has been extensively interpreted from both a molecular and fossil perspective. However, for cryptogamic plants such as ferns, the palaeodiversity remains poorly known. In this study, we describe a new ferny fossil taxon, Drynaria lanpingensis sp. nov. Huang,Su et Zhou(Polypodiaceae), from the late Pliocene of northwestern Yunnan based on fragmentary frond and pinna with in situ spores. The frond is pinnatifid and the pinnae are entirely margined. The sori are arranged in one row on each side of the primary vein. The spores have a semicircular to bean-shaped equatorial view and a tuberculate surface. Taken together with previously described fossils, there are now representatives of three known fossil taxa of Drynaria from the late Pliocene of western Yunnan.These finds suggest that Drynaria diversity was considerable in the region at that time. As Drynaria is a shade-tolerant plant, growing preferably in wet conditions in the understory of forests, its extensive existence may indicate forest vegetation and humid climates in western Yunnan during the late Pliocene.This is in line with results from floristic investigations and palaeoclimatic reconstructions based on fossil floras.
基金supported by the National Natural Science Foundation of China (Grant No. 40776028 and 40621063)National Basic Research Program of China (Grant No. 2007CB 815902)the FANEDD (Grant No. 2005036),and Fok Ying Tong Education Founda-tion (Grant No. 111016)
文摘The equatorial Pacific underwent a significant climate transition during the late Pliocene, which is characterized by cooling of global sea surface temperatures (SSTs) and formation of a marked SST gradient between the eastern and western equatorial Pacific. Moreover, this transition was nearly synchronous with the late Pliocene Northern Hemisphere glaciation. Probing the relationship among solar insolation, low and high latitude processes is the key to unravel the mechanism of this climate transition. A series of statistical methods were used in this study to analyze the orbital components of the equatorial Pacific SST and global ice volume records for the past 5 Ma. We found that integrated solar insolation rather than the monthly mean insolation is the primary external forcing of the late Pliocene climate transition, and that on orbital time scale the SSTs of the eastern and western equatorial Pacific display consistent change rather than a "seesaw" pattern. Changes of Earth’s orbital configuration have been responsible for this climate transition whereas the feedback effects of atmospheric CO2 concentration have further cooled the global climate since the early Cenozoic.
基金supported by the National Basic Research Program of China(2012CB822003)the National Natural Science Foundation of China(41172022 and 41172021)the Fundamental Research Funds for the Central Universities(lzujbky-2012-127)
文摘A number of fossil leaves of the Lauraceae were collected from Tuantian flora of the late Pliocene strata in Yunnan, China. They have a whole leaf shape and well-preserved cuticles. In this paper, features of the architecture and epidermis of three species of the Lauraceae family with ternate venation are reported. Results of the comparison between the venation characteristics of Lauraceae fossils from four fossil floras in the world and those of extant Lauraceae in China suggest that the proportion of Lauraceae species with ternate venation is increasing. The proportion has risen from 10% in the Eocene to 12.5% in the late Pliocene in China, whereas the proportion in the modern era is 21%. Moreover, the proportion of Australian floras with ternate venation has rised from 8.3% to 10% between the Eocene and the Miocene. Because of the effect of the global drought during the Cenozoic era, we suggested that species with ternate venation in Lauraceae have become increasingly prevalent between the Eocene era and the present day in China. Data on Nerriga flora and Maarlake flora since the Eocene era in the Southern Hemisphere show the same trend. While features of the leaf architecture and epidermis of Lindera acuminatissima differ in details. They all have similar identification characteristics with regard to basal eucamptodromous venation, interior 2° present, minor 2° simple brochidodromous, anticlinal walls, no surface ornamentation, lip-like guard cells, outer stomatal ledge plain or dimness, and paracytic stomatal aperture. These differences are also present in extant species. Compared with Lindera tonkinensis, the nearest living relative(NLR) of L. acuminatissima shows that these differences are relevant to the growth, position, and development of leaves. Leaf-type classification statistics of L. acuminatissima indicate that when all fossil leaves are taken into consideration, A-type leaves account for 24%, B-type leaves make up 56%, and C-typy leaves account for 20%. Comparing the above result with that of NLRs, A-type leaves are generally immature spires and cannot be preserved easily, B-type leaves are regular mature leaves and fossilize more easil, and C-type leaves are usually old leaves occurring at the bottom, broken, ill and consumed by worms.
基金This paper is included in the projects CGL2012-38087,CGL2009-12703-C03-03,EHU 10/32(Universidad del País Vasco UPV/EHU)and CGL2012-38358.
文摘The vertebrate fossil record from the Balearic Islands(western Mediterranean)has improved considerably over the past decade,especially in Mallorca and Menorca.In Menorca,the Pliocene terrestrial fauna was updated by the discovery and description of the large-sized leporid Nuralagus,several reptiles and an amphibian.In Mal-lorca,paleontological exploration yielded 2 deposits with a Late Miocene/Early Pliocene chronology,Calóden Rafelino(CdR)and Na Burguesa-1(NB-1).So far,4 new mammalian taxa and 2 new reptiles have been iden-tified for the CdR deposit,whereas the faunal assemblage from the recently discovered deposit(Apr 2012)of NB-1 is currently composed of,at least,6 terrestrial mammals,8 reptiles and an amphibian.Its faunal composi-tion and some primitive characteristics of the obtained taxa suggest that the chronology of this deposit is slight-ly earlier than the CdR.The terrestrial vertebrates recorded in these 2 Mallorcan deposits are changing the view of the paleofaunal assemblage previously known for the Plio-Pleistocene of the island.Morphological charac-teristics displayed by some of the taxa suggest that these faunas would be at the beginning of an isolated evo-lution.In this paper we present a preliminary report on the fossils recovered from the NB-1 deposit,as well as some unpublished data from CdR,and we analyze the whole fauna from both Mallorcan deposits,focusing on taxonomical and paleobiogeographical aspects.
