To understand the acoustic and physical properties of piston core samples collected from the Sunda continental shelf and analyze their distribution patterns,the samples were analyzed in laboratory,from which three pro...To understand the acoustic and physical properties of piston core samples collected from the Sunda continental shelf and analyze their distribution patterns,the samples were analyzed in laboratory,from which three provinces were divided in sound speed,sound speed ratio,porosity,wet bulk density,and maximum shear strength.ProvinceⅠhad lower sound speed and sound speed ratio(<1.04),high porosity,and low wet bulk density.ProvinceⅡhad higher sound speed and sound speed ratio(>1.04),low porosity,and high wet bulk density.ProvinceⅢhad the lowest sound speed and sound speed ratio(0.99),highest porosity(81%),and lowest wet bulk density(1.34 g/cm^(3)).The distribution pattern indicates that sediment movement,sediment source,topography,and hydrodynamic conditions influenced the distribution of acoustic and physical properties.Furthermore,we investigated the relationship of the maximum shear strength to the porosity and wet bulk density,and found that the maximum shear strength was proportional to both the porosity and wet bulk density.This finding has significant implications for ocean engineering applications.展开更多
This paper presents the pollen data from deep_sea sediments of station 17962 from the continental slope of the southern South China Sea. The 8 m long profile covers the last 30 000 years including the late stage of Ma...This paper presents the pollen data from deep_sea sediments of station 17962 from the continental slope of the southern South China Sea. The 8 m long profile covers the last 30 000 years including the late stage of Marine Oxygen Isotope Stage 3, the Last Glacial Maximum, the Termination and the Holocene. The pollen results reveal that lowland rainforest covered the emerged southern continental shelf of the South China Sea (Sunda Land) during the last glacial period at low sea level stand. At the same time, upper montane rainforest on the adjacent islands expanded, showing the climate was cooler than that in present day, but no dryness was indicated. The vegetation and climate experienced great fluctuations including abrupt warming and cooling at the end of the ice age. During the Holocene, expansion of mangroves and lowland rainforest, and significant diminution of pollen influx values suggests warming of the climate, rising of the sea level and the submerge of the shelf.展开更多
Seventy seven surface sediment samples and core samples from the outer Sunda Shelf were analyzed and a number of seismic profiles of the shelf were interpreted. The bottom sediments could be divided into six types: te...Seventy seven surface sediment samples and core samples from the outer Sunda Shelf were analyzed and a number of seismic profiles of the shelf were interpreted. The bottom sediments could be divided into six types: terrigenous sand, biogenic sand, silt sand, clay silt sand, clayey silt and coral reef detritus. Our seismic data showed a thick, prograding Pleistocene deltaic sequence near the shelfbreak and a thin Holocene sedimentary layer on the outer shelf. Eleven thermoluminescence (TL) ages were determined. The oldest relict sediments were derived from Late Pleistocene deposits. Based on sediment types, ages, and origins, five sedimentary areas were identified: area of modern Mekong sediments; insular shelf area receiving modern sediments from small Borneo rivers; shelf area near the Natuna Anambas islands in the southeastern Gulf of Thailand Basin off the Malay Peninsula; area of relict sediments on the outer shelf north of the Natuna Islands, and typical coral reefs and detritus sediments.展开更多
The Sunda basin is located at the north of the Sunda Strait situated between Sumatra and Java islands, Indonesia. It is an early Tertiary typical half-graben basin, in which developed a series of terrigenous clastic s...The Sunda basin is located at the north of the Sunda Strait situated between Sumatra and Java islands, Indonesia. It is an early Tertiary typical half-graben basin, in which developed a series of terrigenous clastic sedimentation. Previous work suggested that the early Tertiary sediments were alluvial, fluvial, lacustrine and swamp deposits, of which the Banuwati formation was alluvial and lacustrine deposits, the Zelda member fluvial deposits, and Gita member fluvial and swamp deposits. In this paper, based on the integrated research on core lithology （including lithology succession and structure）, well log shape, and seismic reflection characteristics, a more detailed sedimentation system was set up as follows： l） In addition to the alluvial, lacustrine, fluvial and the swamp deposits presented in previous work, subaqeous fan, shore-shallow lacustrine, deep lacustrine and turbidite fan, fan delta and delta deposits also developed in this basin. 2） Alluvial fan, subaqeous fan and fan delta deposits occurred on the steep slope adjacent to the synrift boundary fault; while the deltaic depositional system usually distributed on the gentle slope of the basins. 3） The Zelda member that was interpreted as a fluvial deposit in previous work is now interpreted as a subaqueous fan, fan delta, delta and lacustrine deposit system. 4） From the point of view of sedimentology, the evolution of basin could be divided into four stages： the initial subsidence （matching the Banuwati formation）, the rapid subsidence （matching the low Zelda member of Talang Akar formation）, the steady subsidence or fluctuation （matching the middle Zelda member of Talang Akar formation）, and the uplifting （matching the upper Zelda member and the Gita member of Talang Akar formation）. At the initial subsidence stage, the alluvial fan, flood plain, braided stream deposits developed, and then subaqeous fan sedimentation; at the rapid subsidence stage, shore-shallow lacustrine and deep lacustrine deposits and turbidite fans occurred; at the steady subsidence stage, thick fan deltas and delta sandstones developed; and at the uplifting stage, came fluvial （including meandering fiver and the anastomosed stream） and swamp sediments. Sediment supply was mainly from the northwest, secondly from the east. From the beginning to the end of the terrigenous basin evolution, the area of sedimentation was gradually enlarged. The palaeo-topography became increasingly flat.展开更多
CTD data obtained from two oceanographic cruises during June and October 2012 were used to define the water mass characteristics and degree of stratification at the shallow Sunda shelf located at the southern South Ch...CTD data obtained from two oceanographic cruises during June and October 2012 were used to define the water mass characteristics and degree of stratification at the shallow Sunda shelf located at the southern South China Sea. The water masses during both cruises showed characteristics similar (southwest monsoon) to those observed in the adjacent regions. A clustering method was used in which three water masses were classified from the composite dataset. There are WM1 (T 29°C - 31°C, S 32 - 33.5 psu, & σT, ~19.5 - 20.7 kg/m3), WM2 (T 25°C - 29°C, S 32.8 - 33.8 psu, & σT, ~22.3 - 23 kg/m3) and WM3 (T 23°C - 25°C, S33.5 - 34.0, & σT ~22.3 - 23.3 kg/m3). Even though the water masses found were characterized under southwest monsoon characteristics, the degrees of stratification obtained varied between these cruises. The stability of the stratification also plays roles in the distribution of the water masses in the water column. WM2 was found in thermocline layer and most dominant in June compared to in October. In June, WM3 was found under the thermocline layer and absent in October. The stable thermocline caused the denser WM3 cannot mixed with WM2. Higher temperatures and weaker winds during June may have caused the strong stratification, while decreasing temperature and stronger winds of an upcoming northeast monsoon enhanced the vertical mixing during October.展开更多
From the existing literature and data from museum specimens an overview is presented of all currently known terrestrial and semi-aquatic snakes of the Lesser Sunda Islands, in the Wallacean area of Indonesia. In total...From the existing literature and data from museum specimens an overview is presented of all currently known terrestrial and semi-aquatic snakes of the Lesser Sunda Islands, in the Wallacean area of Indonesia. In total, twenty-nine species are known to inhabit the area. Of these eight are endemic to the area： Boiga hoeseli, Coelognathus subradiatus, Dendrelaphis inornatus, Stegonotus florensis, Cylindrophis opisthorhodus, Broghammerus timoriensis, Liasis mackloti and Typhlops schmutzi. Insular endemism is only found at the subspecific level, including Liasis mackloti dunni （Wetar）, Liasis mackloti savuensis （Sawu）, Ramphotyphlops polygrammicus brongersmai （Sumba）, Ramphotyphlops polygrammicus elberti （Lombok） and Ramphotyphlops polygrammicus florensis （Flores）. Such endemism may be due to the relatively young geological age of the Lesser Sunda Islands and that the snake fauna is still underestimated. Taxonomy of the genus Cylindrophis, the species Coelognathus subradiatus, Dendrelaphis inornatus, Cryptelytrops insularis, and the five subspecies of Ramphotyphlops polygrammicus need to be reviewed. Ecological studies are urgently required to establish if the species Broghammerus timoriensis and Liasis mackloti savuensis are endangered and which conservation measures should be taken. Telah dilakukan pengamatan ulang dari kepustakaan yang ada, data dari databank Western Australian Museum, maupun koleksi museum. Hasil tersebut dirangkum dalam suam tinjauan mengenai semua jenis ular yang hidup di darat maupun di air-tawar dari daerah Nusa Tenggara sebagai bagian dari daerah Wallacea. Jumlah jenis yang dapat dipastikan berjumlah dua puluh sembilan jenis, dan delapan di antaranya merupakan jenis yang endemik, yaitu Boiga hoeseli, Coelognathus subradiatus, Dendrelaphis inornatus, Stegonotus florensis, Cylindrophis opisthorhodus, Broghammerus timoriensis, Liasis mackloti dan Typhlops schmutzi. Jenis endemic dalam daerah pulau hanya meliputi anak jenis： Liasis mackloti dunni （Wetar）, Liasis mackloti savuensis （Sawu）, RamphotyphIops polygrammicus brongersmai （Sumba）, Ramphotyphlops polygrammicus elberti （Lombok） dan Ramphotyphlops polygrammicus florensis （Flores）. Hal ini diperkirakan merupakan konsekuensi langsung dari sejarah geologi yang relatif singkat namun dapat juga disebabkan karena kekayaan jenis ular kurang dipelajari dengan lebih seksama. Kedudukan sistematik dari Coelognathus subradiatus, Dendrelaphis inornatus, Cylindrophis boulengeri, C. opisthorhodus, dan ke-lima subspecies Ramphotyphlops polygrammicus serta Cryptelytrops insularis perlu ditinjau kembali. Jenis-jenis yang diperkirakan terancam dan perlu perlindungan adalah jenis-jenis piton Broghammerus timoriensis dan Liasis maekloti savuensis. Penelitian ekologi perlu segara dilakukan untuk menentukan apakah jenis-jenis tersebut perlu perlindungan, dan juga tindakan konservasi yang mana bisa diambil.展开更多
The Sunda Shelf is a prime biodiversity hotspot where some of the planet's most endemic species can be found.Much of the diversity in this important bioregion has been shaped by sea-level fluctuations that took pl...The Sunda Shelf is a prime biodiversity hotspot where some of the planet's most endemic species can be found.Much of the diversity in this important bioregion has been shaped by sea-level fluctuations that took place during the Pleistocene.Using depth contours obtained from the General Bathymetric Chart of the Oceans Grid 2023,we provide high-resolution reconstruction of land areas and palaeo-drainages on the Sunda Shelf at the 50,75,100,and 120 m isobaths,as well as palaeo-catchments at the 120 m isobath,in order to elucidate the history of this region.The maps presented here aim to reconstruct the connection between palaeo-rivers in the Sunda Shelf and contemporary rivers and identify possible dispersal routes and barriers for the floras and faunas/biotas associated with riverine systems found here.展开更多
Using literature published from 2010 onwards, this study investigates the ~3 500 km extension of the shallow shelf current in the South China Sea(SCS) during the winter and summer monsoons. This current is later ackno...Using literature published from 2010 onwards, this study investigates the ~3 500 km extension of the shallow shelf current in the South China Sea(SCS) during the winter and summer monsoons. This current is later acknowledged as the South China Sea shallow shelf Current(SCSSC). This current is primarily driven by monsoonal winds, and influenced by regional river plumes [Zhujiang(Pearl) River, Hong River, Mekong River] and the prominent South China Sea Warm Current(SCSWC) and South China Sea Western Boundary Current(SCSWBC). The current exhibits significant seasonal variations in both direction and pattern. During winter, it flows along the northern South China Sea's(NSCS) shelf and splits into two branches at the east of Hainan Island. One branch enters the Beibu Gulf through the Qiongzhou Strait and forms a major cyclonic circulation within the gulf, while the other branch flows southwestward along the southern coast of Hainan Island. These branches converge around 16°N latitude at the east of the Vietnamese shelf, then flow southward along the Sunda Shelf, where they deflect southwestward in “broadband”forms before curving southeastward along the east coast of Peninsular Malaysia(ECPM) and exiting via the Karimata Strait. In summer, the current exhibits a complex pattern. At the Sunda Shelf, it flows northwestward along the ECPM,then deflects northeastward around 6°N latitude, forming the Sunda Shelf's anti-cyclonic eddy(SSE) and causing upwelling on the east coast of Peninsular Malaysia(ECPMU). Near the eastern Vietnamese shelf, the current splits around 11°-12°N latitude into three distinct currents: the southward-flowing Vietnam Current, the northward-flowing Vietnam Meandering Current(VMC), and the southward-flowing SCSWBC. The VMC flows northward and then deflects northeastward south of Hainan Island, continuing northeastward along the NSCS's shelf and exiting through the Taiwan Strait.展开更多
This paper presents 16500-year-long high-resolution pollen and spore records from sediments of core 18287 on the continental slope of the southern South China Sea. In the period of 16.5―13.9 ka B.P., the low-mountain...This paper presents 16500-year-long high-resolution pollen and spore records from sediments of core 18287 on the continental slope of the southern South China Sea. In the period of 16.5―13.9 ka B.P., the low-mountain rainforest dominated the continental slope of the South China Sea. And in the period of 13.9―10.2 ka B.P., the lowland rainforest and ferns expanded greatly, while the low-mountain rainforest shrank, which indicated a warming at the last deglaciation. Also during this period, the pollen sedi-mentation rates reduced sufficiently. This might imply a rise of the sea level and therefore the sub-mergence of the shelf, resulting in the broadening of the distance between the source area and the slope. After 10.2 ka B.P, decreasing of the fern indicates the early Holocene (10.2―7 ka B.P.) is a cold period, while the increasing of fern marks the rising temperature (7―3.6 ka B.P.).展开更多
This paper presents a 40000-year-long high-resolution mangrove record from sediments of Core 18300,18302 and 18323 on the continental shelf of the southern South China Sea and reconstructs the coast-line changes on Su...This paper presents a 40000-year-long high-resolution mangrove record from sediments of Core 18300,18302 and 18323 on the continental shelf of the southern South China Sea and reconstructs the coast-line changes on Sunda Shelf since the last 40000 years. In the period Marine Isotope 3,the old Sunda Shelf had low sea level,and it was partly exposed. Flourishing vegetations grew on the exposed old land. Mangroves developed along the coastline. On the Last Glacial Maximum,the sea level dropped greatly,coastline moved from inner shelf to outer shelf,the Old Sunda Land exposed further,and the lowering sea level induced the gradual disappearing of mangroves from the inner Sunda Shelf to the outer Sunda Shelf. And pioneer vegetation ferns covered the broadly exposed old land immediately. At the time of the last Deglaciation,sea level rose greatly,the coastline moved to the sea and the Sunda Shelf was drown again. Mangroves were emergent again from outer shelf to inner shelf and developed quickly.展开更多
基金Supported by the National Key R&D Program of China(No.2021YFF0501202)the National Natural Science Foundation of China(Nos.12374428,42176191,U22A2012,12304507)+2 种基金the Guangdong Special Support Key Team Program(Nos.2019BT02H594,GML2021GD0810)the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(No.SML2023SP232)the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(No.24lgqb006)。
文摘To understand the acoustic and physical properties of piston core samples collected from the Sunda continental shelf and analyze their distribution patterns,the samples were analyzed in laboratory,from which three provinces were divided in sound speed,sound speed ratio,porosity,wet bulk density,and maximum shear strength.ProvinceⅠhad lower sound speed and sound speed ratio(<1.04),high porosity,and low wet bulk density.ProvinceⅡhad higher sound speed and sound speed ratio(>1.04),low porosity,and high wet bulk density.ProvinceⅢhad the lowest sound speed and sound speed ratio(0.99),highest porosity(81%),and lowest wet bulk density(1.34 g/cm^(3)).The distribution pattern indicates that sediment movement,sediment source,topography,and hydrodynamic conditions influenced the distribution of acoustic and physical properties.Furthermore,we investigated the relationship of the maximum shear strength to the porosity and wet bulk density,and found that the maximum shear strength was proportional to both the porosity and wet bulk density.This finding has significant implications for ocean engineering applications.
文摘This paper presents the pollen data from deep_sea sediments of station 17962 from the continental slope of the southern South China Sea. The 8 m long profile covers the last 30 000 years including the late stage of Marine Oxygen Isotope Stage 3, the Last Glacial Maximum, the Termination and the Holocene. The pollen results reveal that lowland rainforest covered the emerged southern continental shelf of the South China Sea (Sunda Land) during the last glacial period at low sea level stand. At the same time, upper montane rainforest on the adjacent islands expanded, showing the climate was cooler than that in present day, but no dryness was indicated. The vegetation and climate experienced great fluctuations including abrupt warming and cooling at the end of the ice age. During the Holocene, expansion of mangroves and lowland rainforest, and significant diminution of pollen influx values suggests warming of the climate, rising of the sea level and the submerge of the shelf.
文摘Seventy seven surface sediment samples and core samples from the outer Sunda Shelf were analyzed and a number of seismic profiles of the shelf were interpreted. The bottom sediments could be divided into six types: terrigenous sand, biogenic sand, silt sand, clay silt sand, clayey silt and coral reef detritus. Our seismic data showed a thick, prograding Pleistocene deltaic sequence near the shelfbreak and a thin Holocene sedimentary layer on the outer shelf. Eleven thermoluminescence (TL) ages were determined. The oldest relict sediments were derived from Late Pleistocene deposits. Based on sediment types, ages, and origins, five sedimentary areas were identified: area of modern Mekong sediments; insular shelf area receiving modern sediments from small Borneo rivers; shelf area near the Natuna Anambas islands in the southeastern Gulf of Thailand Basin off the Malay Peninsula; area of relict sediments on the outer shelf north of the Natuna Islands, and typical coral reefs and detritus sediments.
文摘The Sunda basin is located at the north of the Sunda Strait situated between Sumatra and Java islands, Indonesia. It is an early Tertiary typical half-graben basin, in which developed a series of terrigenous clastic sedimentation. Previous work suggested that the early Tertiary sediments were alluvial, fluvial, lacustrine and swamp deposits, of which the Banuwati formation was alluvial and lacustrine deposits, the Zelda member fluvial deposits, and Gita member fluvial and swamp deposits. In this paper, based on the integrated research on core lithology （including lithology succession and structure）, well log shape, and seismic reflection characteristics, a more detailed sedimentation system was set up as follows： l） In addition to the alluvial, lacustrine, fluvial and the swamp deposits presented in previous work, subaqeous fan, shore-shallow lacustrine, deep lacustrine and turbidite fan, fan delta and delta deposits also developed in this basin. 2） Alluvial fan, subaqeous fan and fan delta deposits occurred on the steep slope adjacent to the synrift boundary fault; while the deltaic depositional system usually distributed on the gentle slope of the basins. 3） The Zelda member that was interpreted as a fluvial deposit in previous work is now interpreted as a subaqueous fan, fan delta, delta and lacustrine deposit system. 4） From the point of view of sedimentology, the evolution of basin could be divided into four stages： the initial subsidence （matching the Banuwati formation）, the rapid subsidence （matching the low Zelda member of Talang Akar formation）, the steady subsidence or fluctuation （matching the middle Zelda member of Talang Akar formation）, and the uplifting （matching the upper Zelda member and the Gita member of Talang Akar formation）. At the initial subsidence stage, the alluvial fan, flood plain, braided stream deposits developed, and then subaqeous fan sedimentation; at the rapid subsidence stage, shore-shallow lacustrine and deep lacustrine deposits and turbidite fans occurred; at the steady subsidence stage, thick fan deltas and delta sandstones developed; and at the uplifting stage, came fluvial （including meandering fiver and the anastomosed stream） and swamp sediments. Sediment supply was mainly from the northwest, secondly from the east. From the beginning to the end of the terrigenous basin evolution, the area of sedimentation was gradually enlarged. The palaeo-topography became increasingly flat.
文摘CTD data obtained from two oceanographic cruises during June and October 2012 were used to define the water mass characteristics and degree of stratification at the shallow Sunda shelf located at the southern South China Sea. The water masses during both cruises showed characteristics similar (southwest monsoon) to those observed in the adjacent regions. A clustering method was used in which three water masses were classified from the composite dataset. There are WM1 (T 29°C - 31°C, S 32 - 33.5 psu, & σT, ~19.5 - 20.7 kg/m3), WM2 (T 25°C - 29°C, S 32.8 - 33.8 psu, & σT, ~22.3 - 23 kg/m3) and WM3 (T 23°C - 25°C, S33.5 - 34.0, & σT ~22.3 - 23.3 kg/m3). Even though the water masses found were characterized under southwest monsoon characteristics, the degrees of stratification obtained varied between these cruises. The stability of the stratification also plays roles in the distribution of the water masses in the water column. WM2 was found in thermocline layer and most dominant in June compared to in October. In June, WM3 was found under the thermocline layer and absent in October. The stable thermocline caused the denser WM3 cannot mixed with WM2. Higher temperatures and weaker winds during June may have caused the strong stratification, while decreasing temperature and stronger winds of an upcoming northeast monsoon enhanced the vertical mixing during October.
文摘From the existing literature and data from museum specimens an overview is presented of all currently known terrestrial and semi-aquatic snakes of the Lesser Sunda Islands, in the Wallacean area of Indonesia. In total, twenty-nine species are known to inhabit the area. Of these eight are endemic to the area： Boiga hoeseli, Coelognathus subradiatus, Dendrelaphis inornatus, Stegonotus florensis, Cylindrophis opisthorhodus, Broghammerus timoriensis, Liasis mackloti and Typhlops schmutzi. Insular endemism is only found at the subspecific level, including Liasis mackloti dunni （Wetar）, Liasis mackloti savuensis （Sawu）, Ramphotyphlops polygrammicus brongersmai （Sumba）, Ramphotyphlops polygrammicus elberti （Lombok） and Ramphotyphlops polygrammicus florensis （Flores）. Such endemism may be due to the relatively young geological age of the Lesser Sunda Islands and that the snake fauna is still underestimated. Taxonomy of the genus Cylindrophis, the species Coelognathus subradiatus, Dendrelaphis inornatus, Cryptelytrops insularis, and the five subspecies of Ramphotyphlops polygrammicus need to be reviewed. Ecological studies are urgently required to establish if the species Broghammerus timoriensis and Liasis mackloti savuensis are endangered and which conservation measures should be taken. Telah dilakukan pengamatan ulang dari kepustakaan yang ada, data dari databank Western Australian Museum, maupun koleksi museum. Hasil tersebut dirangkum dalam suam tinjauan mengenai semua jenis ular yang hidup di darat maupun di air-tawar dari daerah Nusa Tenggara sebagai bagian dari daerah Wallacea. Jumlah jenis yang dapat dipastikan berjumlah dua puluh sembilan jenis, dan delapan di antaranya merupakan jenis yang endemik, yaitu Boiga hoeseli, Coelognathus subradiatus, Dendrelaphis inornatus, Stegonotus florensis, Cylindrophis opisthorhodus, Broghammerus timoriensis, Liasis mackloti dan Typhlops schmutzi. Jenis endemic dalam daerah pulau hanya meliputi anak jenis： Liasis mackloti dunni （Wetar）, Liasis mackloti savuensis （Sawu）, RamphotyphIops polygrammicus brongersmai （Sumba）, Ramphotyphlops polygrammicus elberti （Lombok） dan Ramphotyphlops polygrammicus florensis （Flores）. Hal ini diperkirakan merupakan konsekuensi langsung dari sejarah geologi yang relatif singkat namun dapat juga disebabkan karena kekayaan jenis ular kurang dipelajari dengan lebih seksama. Kedudukan sistematik dari Coelognathus subradiatus, Dendrelaphis inornatus, Cylindrophis boulengeri, C. opisthorhodus, dan ke-lima subspecies Ramphotyphlops polygrammicus serta Cryptelytrops insularis perlu ditinjau kembali. Jenis-jenis yang diperkirakan terancam dan perlu perlindungan adalah jenis-jenis piton Broghammerus timoriensis dan Liasis maekloti savuensis. Penelitian ekologi perlu segara dilakukan untuk menentukan apakah jenis-jenis tersebut perlu perlindungan, dan juga tindakan konservasi yang mana bisa diambil.
基金supported by grants from the Selangor Water Management Authority(Grant No:53-31-08-02-008(SC))Senheng Electric(KL)Sdn.Bhd.(Grant No:55-31-08-02-007(SC))
文摘The Sunda Shelf is a prime biodiversity hotspot where some of the planet's most endemic species can be found.Much of the diversity in this important bioregion has been shaped by sea-level fluctuations that took place during the Pleistocene.Using depth contours obtained from the General Bathymetric Chart of the Oceans Grid 2023,we provide high-resolution reconstruction of land areas and palaeo-drainages on the Sunda Shelf at the 50,75,100,and 120 m isobaths,as well as palaeo-catchments at the 120 m isobath,in order to elucidate the history of this region.The maps presented here aim to reconstruct the connection between palaeo-rivers in the Sunda Shelf and contemporary rivers and identify possible dispersal routes and barriers for the floras and faunas/biotas associated with riverine systems found here.
基金Long-Term Research Grant Scheme (LRGS:56041)Interaction of Ocean Dynamics With The Climate System of Past,Present,and Future Using Ocean Observation Integrated Data and Numerical Modeling。
文摘Using literature published from 2010 onwards, this study investigates the ~3 500 km extension of the shallow shelf current in the South China Sea(SCS) during the winter and summer monsoons. This current is later acknowledged as the South China Sea shallow shelf Current(SCSSC). This current is primarily driven by monsoonal winds, and influenced by regional river plumes [Zhujiang(Pearl) River, Hong River, Mekong River] and the prominent South China Sea Warm Current(SCSWC) and South China Sea Western Boundary Current(SCSWBC). The current exhibits significant seasonal variations in both direction and pattern. During winter, it flows along the northern South China Sea's(NSCS) shelf and splits into two branches at the east of Hainan Island. One branch enters the Beibu Gulf through the Qiongzhou Strait and forms a major cyclonic circulation within the gulf, while the other branch flows southwestward along the southern coast of Hainan Island. These branches converge around 16°N latitude at the east of the Vietnamese shelf, then flow southward along the Sunda Shelf, where they deflect southwestward in “broadband”forms before curving southeastward along the east coast of Peninsular Malaysia(ECPM) and exiting via the Karimata Strait. In summer, the current exhibits a complex pattern. At the Sunda Shelf, it flows northwestward along the ECPM,then deflects northeastward around 6°N latitude, forming the Sunda Shelf's anti-cyclonic eddy(SSE) and causing upwelling on the east coast of Peninsular Malaysia(ECPMU). Near the eastern Vietnamese shelf, the current splits around 11°-12°N latitude into three distinct currents: the southward-flowing Vietnam Current, the northward-flowing Vietnam Meandering Current(VMC), and the southward-flowing SCSWBC. The VMC flows northward and then deflects northeastward south of Hainan Island, continuing northeastward along the NSCS's shelf and exiting through the Taiwan Strait.
基金Suppored by the National Key Basic Development Research Program (Grant No. G2000078500)
文摘This paper presents 16500-year-long high-resolution pollen and spore records from sediments of core 18287 on the continental slope of the southern South China Sea. In the period of 16.5―13.9 ka B.P., the low-mountain rainforest dominated the continental slope of the South China Sea. And in the period of 13.9―10.2 ka B.P., the lowland rainforest and ferns expanded greatly, while the low-mountain rainforest shrank, which indicated a warming at the last deglaciation. Also during this period, the pollen sedi-mentation rates reduced sufficiently. This might imply a rise of the sea level and therefore the sub-mergence of the shelf, resulting in the broadening of the distance between the source area and the slope. After 10.2 ka B.P, decreasing of the fern indicates the early Holocene (10.2―7 ka B.P.) is a cold period, while the increasing of fern marks the rising temperature (7―3.6 ka B.P.).
基金the National Key Basic Develop Research Program (Grant No.G2000078500)
文摘This paper presents a 40000-year-long high-resolution mangrove record from sediments of Core 18300,18302 and 18323 on the continental shelf of the southern South China Sea and reconstructs the coast-line changes on Sunda Shelf since the last 40000 years. In the period Marine Isotope 3,the old Sunda Shelf had low sea level,and it was partly exposed. Flourishing vegetations grew on the exposed old land. Mangroves developed along the coastline. On the Last Glacial Maximum,the sea level dropped greatly,coastline moved from inner shelf to outer shelf,the Old Sunda Land exposed further,and the lowering sea level induced the gradual disappearing of mangroves from the inner Sunda Shelf to the outer Sunda Shelf. And pioneer vegetation ferns covered the broadly exposed old land immediately. At the time of the last Deglaciation,sea level rose greatly,the coastline moved to the sea and the Sunda Shelf was drown again. Mangroves were emergent again from outer shelf to inner shelf and developed quickly.
