Breakthroughs have been made in natural gas exploration in Sinian reservoirs in the Tongwan Palaeo-uplift,Sichuan Basin,recently.However,there are disputes with regard to the genetic mechanisms of natural gas reservoi...Breakthroughs have been made in natural gas exploration in Sinian reservoirs in the Tongwan Palaeo-uplift,Sichuan Basin,recently.However,there are disputes with regard to the genetic mechanisms of natural gas reservoirs.The development law of asphalts in the Sinian reservoirs may play an extremely important role in the study of the relationships between palaeo oil and gas reservoirs.Accordingly,researches were conducted on the features and development patterns of asphalts in the Sinian reservoirs in this area.The following research results were obtained.(1)Asphalts in the Sinian reservoirs were developed after the important hydrothermal event in the Sichuan Basin,namely the wellknown Emei Taphrogeny in the mid-late Permian Period.(2)Distribution of asphalts is related to palaeo oil reservoirs under the control of palaeo-structures of Indosinian-Yanshanian Period,when the palaeo-structures contained high content of asphalts in the high positions of the palaeo-uplift.(3)Large-scale oil and gas accumulations in the Sinian reservoirs occurred in the Indosinian-Yanshanian Period to generate the Leshan-Ziyang and Gaoshiti-Moxi-Guang'an palaeo oil reservoirs.Cracking of crude oil in the major parts of these palaeo oil reservoirs controlled the development of the present natural gas reservoirs.(4)The development of asphalts in the Sinian reservoirs indicates that hydrocarbons in the Dengying Formation originated from Cambrian source rocks and natural gas accumulated in the Sinian reservoirs are products of late-stage cracking of the Sinian reservoirs.(5)The Sinian palaeo-structures of Indosinian-Yanshanian Period in the Sichuan Basin are favorable regions for the development of the Sinian reservoirs,where discoveries and exploration practices will play an important role in the era of Sinian natural gas development in China.展开更多
The Changning - Menglian belt , located between the Baoshan - Gengma massif and the Simao - Lincang massif in Western Yunnan , preserves the complete record of a suture zone and the most continuous record of deep wate...The Changning - Menglian belt , located between the Baoshan - Gengma massif and the Simao - Lincang massif in Western Yunnan , preserves the complete record of a suture zone and the most continuous record of deep water sedimentation , representing the main branch of the Palaeo - Tethys polyisland ocean in the Hercynian - Indo-sinian stage .This belt could be further subdivided into three tectono - lithofacies zones . In the east zone , terrigenous elastics , argillaceous ,marl-argillaceous and silicate sedi-ments lie on the metamorphosed Early Palaeozoic base ment in concealed unconformity , representing deep water sediments on a passive continental margin . The central zone , although the basement rocks are absent from outcropping here , includes a contemporary complex of various sedimentary types , among them one type is of deep ocean sediments represented by radiolarian bedded chert , appearing from at least early Early Devonian to the Middle Triassic . Another type includes pure carbonates of the Early Carboniferous to the Late Permian , a type of shallow water carbonate platform on seamount or oceanic plateau within an ocean basin . In the west zone , the Permo - Carboniferous terrigenous elastics , argillaceous and silicate sediments appear again -representing the passive continental slope sedimentation in the east of the Baoshan - Gengma massif .As the Permo-Carboniferous rock types,sedimentary environments and palaeontological characters of the east and west zones are quite similar , we hold that these two zones were originally formed all on the eastern continental slope of the Baoshan - Gengma massif , and were separated due to eastward thrust later in the Indosinian orogeny . Intense thrust compacting also resulted in tectonic melange in the central zone , which is displayed by shallow water carbonates overlapping on or embedded in deep water volcanics . In the Lancangjiang belt , the Permo - Carboniferous are very complicated in sedimentary types which include island arc volcanics , deep water turbidites, silicolites and shallow water carbonates , representing the active continental margin in the west of the Simao massif. Whether there existed by Early Permi an, a Lincang magma tic arc still awaits further evidence . From the Late Permian,both the Changning-Meng-lian belt and the Lancangjiang belt experienced important sedimentary and volanic events which took place contemporaneously or penecontemporaneously but with different characters . Evidence for the Lincang magmatic arc began to be apparent , and the turbidite deep water basin in the Lancangjiang belt closed . Nevertheless , the Palaeo - Tethys oceanic basin , represented by the Changning - Menglian suture zone , existed until the Mid-dle Triassic . In the Late Triassic . massifs of Baoshan -Gengma ,Simao - Lincang ,collided and aggregated ,resulting in the disappearance of the Palaeo - Tethys ocean .展开更多
Estimates of the palaeo subaerial wind direction were studied systematically for the first time by using the anisotropy of loess magnetic susceptibility (AMS) measurements in the northwestern China. One hundred and f...Estimates of the palaeo subaerial wind direction were studied systematically for the first time by using the anisotropy of loess magnetic susceptibility (AMS) measurements in the northwestern China. One hundred and forty undisturbed oriented aeolian loess samples were collected from Lanzhou, Linxia and Wudu areas for AMS measurements, which indicated the subaerial wind directions were not the same while the loess deposited. From the Early Pleistocene to Middle Pleistocene till Late Pleistocene, the wind direction experienced an anticlockwise rotation in the studied area. We suggested this change was related to the uplift of the Qinghai Xizang Plateau and the adjustment of current and landform effects.展开更多
The last deglaciation, a key period for understanding present and future climate changes, has long been the hot topic for palaeoclimatological study. The Qinghai-Tibetan Plateau（QTP） is often a target study area for...The last deglaciation, a key period for understanding present and future climate changes, has long been the hot topic for palaeoclimatological study. The Qinghai-Tibetan Plateau（QTP） is often a target study area for understanding hemispheric, or even global environment changes. The glacial landforms on the QTP provide a unique perspective for its climate change. In order to investigate the onset of the last deglaciation at the QTP and its regional correlation, the terrestrial cosmogenic nuclides（TCN） 10 Be and 26 Al surface exposure dating was chosen to date the roche moutonnée, the polished surface and the moraine debris located at the palaeo-Daocheng Ice Cap（pDIC）, southeastern QTP. Our results show that the onset of the last deglaciation is at about 19 ka, followed by another warming event occurring around 15 ka in the p-DIC area. These timings agree well with other records, e.g. equivalent with a rapid sea level rise at 19 ka and the onset of B？lling warming event at about 15 ka. Thus, our new data can provide good reveal constraint on the climate evolution at the QTP.展开更多
The glacial landforms of the Qinghai-Tibetan Plateau （QTP） provide a unique opportunity to research hemispheric and global environmental changes. In this study, we focus on the glacial history of the palaeo-Daocheng...The glacial landforms of the Qinghai-Tibetan Plateau （QTP） provide a unique opportunity to research hemispheric and global environmental changes. In this study, we focus on the glacial history of the palaeo-Daocheng Ice Cap （p-DIC） in the southeastern QTP during the last glacial cycle. Based on field investigations, morphostratigraphy, and surface exposure dating of roche moutonnée, polished surface and moraine debris through the terrestrial cosmogenic nuclides （TCN） ^10Be and ^26Al. We identify glacial deposits of the last deglaciation, with minimum ages of 14.9±1.3-18.7±1.7 ka, the Last Glacial Maximum （LGM） of 24.7±2.2 ka, and the early part of the last glacial period （marine oxygen isotope stage （MIS） 3） of 37.1±3.4-45.2±3.9 ka. Our results show that in this region, the extent of the glacial advance during MIS 3 was larger than that during the traditional LGM （MIS 2）. These ages are consistent with prior chronologies, and the ^10Be age is consistent with the ^26Al age for the same sample. Thus, these data provide reliable constraints on climate change in the QTP, during the last glaciation.展开更多
The variation of the Asian winter monsoonal strength has seriously affected the climate and environmental conditions in the Asian monsoonal region, and even in marginal islands and the ocean in the East Asian region. ...The variation of the Asian winter monsoonal strength has seriously affected the climate and environmental conditions in the Asian monsoonal region, and even in marginal islands and the ocean in the East Asian region. However, relevant under-standing remains unclear due to the lack of suitable geological materials and effective proxies in the key study areas. Here, we present a grain-size record derived from the palaeo-aeolian sand dune in the southeastern Mu Us Desert, together with other proxies and OSL dating, which reflect a relatively detailed history of the winter monsoon and abrupt environmental events during the past 4.2 ka. Our grain-size standard deviation model indicated that 〉224 μm content can be considered as an indicator of the intensity of Asian winter monsoon, and it shows declined around 4.2–2.1 ka, enhanced but unstable in 2.1–0.9 ka, and obviously stronger since then. In addition, several typical climate events were also documented, forced by the periodic variation of winter monsoonal intensity. These include the cold intervals of 4.2, 2.8, 1.4 ka, and the Little Ice Age （LIA）, and relatively warm sub-phases around 3.0, 2.1, 1.8 ka, and the Medieval Warm Period （MWP）, which were roughly accordant with the records of the aeolian materials, peat, stalagmites, ice cores, and sea sediments in various latitudes of the Northern Hemisphere. Combined with the previous progresses of the Asian summer monsoon, we prelimi-narily confirmed a millennial-scale anti-correlation of Asian winter and summer monsoons in the Late Holocene epoch. This study suggests that the evolution of the palaeo-aeolian sand dune has the potential for comprehending the history of Asian monsoon across the desert regions of the modern Asian monsoonal margin in northern China.展开更多
Palaeo-notch sediment, accumulated in lacustrine environment, is a reliable proxy material for palaeoclimatic and palaeoenvironmental research. In this study, we collected a palaeo-notch sediment profile from the Blom...Palaeo-notch sediment, accumulated in lacustrine environment, is a reliable proxy material for palaeoclimatic and palaeoenvironmental research. In this study, we collected a palaeo-notch sediment profile from the Blomstrandhalv?ya, used multiple geochemical proxies to reconstruct palaleoproductivity variations, and investigated their link to climatic records from surrounding regions. C/N atomic ratios and carbon isotope indicate that organic matter in the sediment is mainly derived from lacustrine algae. Toward the surface sediment, the TOC, TN, P contents and the reconstructed palaeoproductivity show remarkable fluctuations with several peaks and troughs, opposite to the variation trend of the CaCO3 contents. Changes in the reconstructed palaeoproductivity are in good agreement with palaeoclimatic records from the surrounding regions, and three interruptions are likely linked to the well-known cooling periods around 1900 BP, 2800 BP and 4200 BP. Thus palaeoproductivity variations on the Blomstrandhalv?ya are mainly driven by climate changes; palaeoproductivity increase during warmer periods, and vice versa. This study will help the research of Arctic lake ecosystem and its response to climate change.展开更多
淮河流域特大暴雨洪水灾害严重威胁经济社会发展,其防洪减灾和水资源开发利用,急需超长时间尺度河流洪水水文学数据资料的支撑。全新世古洪水水文学的研究,为淮河流域全新世洪水水文数据发掘提供了重要途径。利用河流地貌学、沉积学、...淮河流域特大暴雨洪水灾害严重威胁经济社会发展,其防洪减灾和水资源开发利用,急需超长时间尺度河流洪水水文学数据资料的支撑。全新世古洪水水文学的研究,为淮河流域全新世洪水水文数据发掘提供了重要途径。利用河流地貌学、沉积学、水文学和年代学等多学科交叉的方法,获取淮河中上游全新世万年来实际发生过的特大暴雨洪水事件的沉积学记录,采用多种水文模型模拟恢复与检验,获得古洪水事件的洪峰水位和流量数据。淮河干流桐柏东段基岩峡谷的研究发现,过去10 000 a以来发生多次特大洪水事件,尤其是发生在3.1 ka B.P.和1.5 ka B.P.时期的古洪水事件,洪峰水位最高,洪峰流量可达14 300~16 000 m^(3)/s,淮河支流汝河遂平段的调查研究和测年断代表明,在(12.0-11.2) ka B.P.、(4.2-4.0) ka B.P.和(3.2-3.0) ka B.P.,分别发生过3期古洪水事件。而支流沙河在(1.45-1.55) ka B.P.发生过特大泛滥洪水事件,对应于中国历史上南北朝时期的严重气候恶化阶段。这些时段处在全球性气候事件、气候恶化或气候转折阶段。在这些时段,季风状态极其不稳定,变率增大,导致气候异常,极端性变化频繁,既有严重干旱,又有特大洪水事件发生。因此,在全新世来说,淮河流域特大暴雨洪水事件并不必然的与温暖湿润气候阶段相联系。这些研究丰富了高分辨率气候水文事件的内涵,对于深刻理解区域气候水文系统对于全球变化的响应规律具有重要的科学意义。展开更多
Middle Permian palaeo-seamounts in the area of Bayan Har are generally com-posed of volcanic basement and carbonate cap. Basaltic lava, volcanic breecia and polymictic breccia can be identified as the main kinds of ro...Middle Permian palaeo-seamounts in the area of Bayan Har are generally com-posed of volcanic basement and carbonate cap. Basaltic lava, volcanic breecia and polymictic breccia can be identified as the main kinds of rock in the basement of palaeo-seamounts. Mas-sive bioclastic limestone and reef framestone formed the carbonate cap of the palaeo-sea- mounts. The contact relationship between carbonate cap and volcanic basement is a kind of conformity or depositional unconformity. Study of the structure and petrology of palaeo-sea- mounts suggests that the evolution history of the palaeo-seamounts in this area can be divided into five stages at least. They are the origin of the first volcanic basement, the formation of the first carbonate cap, the breaking of the first carbonate cap by renewed volcanism, the deposition of red calcareous mudstone and the rebuilding of the second carbonate cap at last. In one of the palaeo-seamounts, volcanic activation took place even after the reconstruction of the second carbonate cap. Lots of fusulinid fossils, such as Neoschwagerina craticulifera Schwager, Schwagerina sp. and Verbeekina sp., were found both in the carbonate cap and volcanic base-ment, showing that the palaeo-seamounts were originated and developed within the Maokou stage of Middle Permian.展开更多
The palaeo-forest vestige has been found for the first time on the sea floor of Shenhuwan Gulf, Jinjiang County, Fujian Province (N24°38′, E118°39′) during my seismic investigation in July, 1986.
The Nansha sea area is located in the place where the Pacific Ocean plate, In-dian-Australian plate and Eurasian plate meet, and therefore, its formation and evolu-tion are both constrained by those three plates. It i...The Nansha sea area is located in the place where the Pacific Ocean plate, In-dian-Australian plate and Eurasian plate meet, and therefore, its formation and evolu-tion are both constrained by those three plates. It is a semi-closed marginal sea area,which is only connected with the Indian and the Pacific Ocean by channels. TheSr-O isotopic composition of sediments in this area was systematically studied for fur-ther understanding of its formation and evolution. The range of our investigation islimited to the area of 105-118°E and 3 - 12°N. The surface sediments from 36 sta-tions, which are distributed in the above area, were analyzed. All of the展开更多
黄河流域古河道的变迁对文化遗址形成的影响,是黄河文化研究的重要科学问题之一。内蒙古巴彦淖尔国家地质公园位于黄河中上游的河套盆地,公园内汉代临戎古城遗址的位置一直存在争论,确定黄河古河道与其相对位置关系是关键。通过对临戎...黄河流域古河道的变迁对文化遗址形成的影响,是黄河文化研究的重要科学问题之一。内蒙古巴彦淖尔国家地质公园位于黄河中上游的河套盆地,公园内汉代临戎古城遗址的位置一直存在争论,确定黄河古河道与其相对位置关系是关键。通过对临戎古城遗址周边10 km范围进行网格化槽型钻取心,利用钻孔数据构建三维粒度属性模型与沉积结构模型,对隐伏的古河道位置进行了较为精准地确定;并通过钻孔岩心沉积相分析与年代学测试,对古河道的沉积结构与年代进行了验证。结果表明,临戎古城遗址西3 km处存在(2.39±0.24) ka~(1.36±0.05) Cal ka BP的黄河古河道,自南向北流经临戎城西。以此确定的黄河与朔方郡各属县治城的相对位置符合史料的记载。本研究从沉积学角度为巴彦淖尔国家地质公园临戎古城遗址位置的考证提供了地质科学依据。展开更多
文摘Breakthroughs have been made in natural gas exploration in Sinian reservoirs in the Tongwan Palaeo-uplift,Sichuan Basin,recently.However,there are disputes with regard to the genetic mechanisms of natural gas reservoirs.The development law of asphalts in the Sinian reservoirs may play an extremely important role in the study of the relationships between palaeo oil and gas reservoirs.Accordingly,researches were conducted on the features and development patterns of asphalts in the Sinian reservoirs in this area.The following research results were obtained.(1)Asphalts in the Sinian reservoirs were developed after the important hydrothermal event in the Sichuan Basin,namely the wellknown Emei Taphrogeny in the mid-late Permian Period.(2)Distribution of asphalts is related to palaeo oil reservoirs under the control of palaeo-structures of Indosinian-Yanshanian Period,when the palaeo-structures contained high content of asphalts in the high positions of the palaeo-uplift.(3)Large-scale oil and gas accumulations in the Sinian reservoirs occurred in the Indosinian-Yanshanian Period to generate the Leshan-Ziyang and Gaoshiti-Moxi-Guang'an palaeo oil reservoirs.Cracking of crude oil in the major parts of these palaeo oil reservoirs controlled the development of the present natural gas reservoirs.(4)The development of asphalts in the Sinian reservoirs indicates that hydrocarbons in the Dengying Formation originated from Cambrian source rocks and natural gas accumulated in the Sinian reservoirs are products of late-stage cracking of the Sinian reservoirs.(5)The Sinian palaeo-structures of Indosinian-Yanshanian Period in the Sichuan Basin are favorable regions for the development of the Sinian reservoirs,where discoveries and exploration practices will play an important role in the era of Sinian natural gas development in China.
文摘The Changning - Menglian belt , located between the Baoshan - Gengma massif and the Simao - Lincang massif in Western Yunnan , preserves the complete record of a suture zone and the most continuous record of deep water sedimentation , representing the main branch of the Palaeo - Tethys polyisland ocean in the Hercynian - Indo-sinian stage .This belt could be further subdivided into three tectono - lithofacies zones . In the east zone , terrigenous elastics , argillaceous ,marl-argillaceous and silicate sedi-ments lie on the metamorphosed Early Palaeozoic base ment in concealed unconformity , representing deep water sediments on a passive continental margin . The central zone , although the basement rocks are absent from outcropping here , includes a contemporary complex of various sedimentary types , among them one type is of deep ocean sediments represented by radiolarian bedded chert , appearing from at least early Early Devonian to the Middle Triassic . Another type includes pure carbonates of the Early Carboniferous to the Late Permian , a type of shallow water carbonate platform on seamount or oceanic plateau within an ocean basin . In the west zone , the Permo - Carboniferous terrigenous elastics , argillaceous and silicate sediments appear again -representing the passive continental slope sedimentation in the east of the Baoshan - Gengma massif .As the Permo-Carboniferous rock types,sedimentary environments and palaeontological characters of the east and west zones are quite similar , we hold that these two zones were originally formed all on the eastern continental slope of the Baoshan - Gengma massif , and were separated due to eastward thrust later in the Indosinian orogeny . Intense thrust compacting also resulted in tectonic melange in the central zone , which is displayed by shallow water carbonates overlapping on or embedded in deep water volcanics . In the Lancangjiang belt , the Permo - Carboniferous are very complicated in sedimentary types which include island arc volcanics , deep water turbidites, silicolites and shallow water carbonates , representing the active continental margin in the west of the Simao massif. Whether there existed by Early Permi an, a Lincang magma tic arc still awaits further evidence . From the Late Permian,both the Changning-Meng-lian belt and the Lancangjiang belt experienced important sedimentary and volanic events which took place contemporaneously or penecontemporaneously but with different characters . Evidence for the Lincang magmatic arc began to be apparent , and the turbidite deep water basin in the Lancangjiang belt closed . Nevertheless , the Palaeo - Tethys oceanic basin , represented by the Changning - Menglian suture zone , existed until the Mid-dle Triassic . In the Late Triassic . massifs of Baoshan -Gengma ,Simao - Lincang ,collided and aggregated ,resulting in the disappearance of the Palaeo - Tethys ocean .
文摘Estimates of the palaeo subaerial wind direction were studied systematically for the first time by using the anisotropy of loess magnetic susceptibility (AMS) measurements in the northwestern China. One hundred and forty undisturbed oriented aeolian loess samples were collected from Lanzhou, Linxia and Wudu areas for AMS measurements, which indicated the subaerial wind directions were not the same while the loess deposited. From the Early Pleistocene to Middle Pleistocene till Late Pleistocene, the wind direction experienced an anticlockwise rotation in the studied area. We suggested this change was related to the uplift of the Qinghai Xizang Plateau and the adjustment of current and landform effects.
基金supported by the National Excellent Doctoral Dissertation cultivation project of Nanjing Normal University (Grant No. 2012BS0005)the National Natural Science Foundation of China (Grant No. 40572097)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘The last deglaciation, a key period for understanding present and future climate changes, has long been the hot topic for palaeoclimatological study. The Qinghai-Tibetan Plateau（QTP） is often a target study area for understanding hemispheric, or even global environment changes. The glacial landforms on the QTP provide a unique perspective for its climate change. In order to investigate the onset of the last deglaciation at the QTP and its regional correlation, the terrestrial cosmogenic nuclides（TCN） 10 Be and 26 Al surface exposure dating was chosen to date the roche moutonnée, the polished surface and the moraine debris located at the palaeo-Daocheng Ice Cap（pDIC）, southeastern QTP. Our results show that the onset of the last deglaciation is at about 19 ka, followed by another warming event occurring around 15 ka in the p-DIC area. These timings agree well with other records, e.g. equivalent with a rapid sea level rise at 19 ka and the onset of B？lling warming event at about 15 ka. Thus, our new data can provide good reveal constraint on the climate evolution at the QTP.
基金supported by the National Natural Science Foundation of China (Grant No.40572097)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) (Grant No.164320H116)by the Yulong Mountain tourism development and management committee special project
文摘The glacial landforms of the Qinghai-Tibetan Plateau （QTP） provide a unique opportunity to research hemispheric and global environmental changes. In this study, we focus on the glacial history of the palaeo-Daocheng Ice Cap （p-DIC） in the southeastern QTP during the last glacial cycle. Based on field investigations, morphostratigraphy, and surface exposure dating of roche moutonnée, polished surface and moraine debris through the terrestrial cosmogenic nuclides （TCN） ^10Be and ^26Al. We identify glacial deposits of the last deglaciation, with minimum ages of 14.9±1.3-18.7±1.7 ka, the Last Glacial Maximum （LGM） of 24.7±2.2 ka, and the early part of the last glacial period （marine oxygen isotope stage （MIS） 3） of 37.1±3.4-45.2±3.9 ka. Our results show that in this region, the extent of the glacial advance during MIS 3 was larger than that during the traditional LGM （MIS 2）. These ages are consistent with prior chronologies, and the ^10Be age is consistent with the ^26Al age for the same sample. Thus, these data provide reliable constraints on climate change in the QTP, during the last glaciation.
基金funded by the Knowledge Innovation Program of the Chinese Academy of Sciences (No. KZZD-EW-04-04)the National Natural Science Foundation of China (Nos., 41271215, 41501220)+1 种基金the China Postdoctoral Science Foundation (No. 2015M570861)the State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University (No. 2015-KF-13)
文摘The variation of the Asian winter monsoonal strength has seriously affected the climate and environmental conditions in the Asian monsoonal region, and even in marginal islands and the ocean in the East Asian region. However, relevant under-standing remains unclear due to the lack of suitable geological materials and effective proxies in the key study areas. Here, we present a grain-size record derived from the palaeo-aeolian sand dune in the southeastern Mu Us Desert, together with other proxies and OSL dating, which reflect a relatively detailed history of the winter monsoon and abrupt environmental events during the past 4.2 ka. Our grain-size standard deviation model indicated that 〉224 μm content can be considered as an indicator of the intensity of Asian winter monsoon, and it shows declined around 4.2–2.1 ka, enhanced but unstable in 2.1–0.9 ka, and obviously stronger since then. In addition, several typical climate events were also documented, forced by the periodic variation of winter monsoonal intensity. These include the cold intervals of 4.2, 2.8, 1.4 ka, and the Little Ice Age （LIA）, and relatively warm sub-phases around 3.0, 2.1, 1.8 ka, and the Medieval Warm Period （MWP）, which were roughly accordant with the records of the aeolian materials, peat, stalagmites, ice cores, and sea sediments in various latitudes of the Northern Hemisphere. Combined with the previous progresses of the Asian summer monsoon, we prelimi-narily confirmed a millennial-scale anti-correlation of Asian winter and summer monsoons in the Late Holocene epoch. This study suggests that the evolution of the palaeo-aeolian sand dune has the potential for comprehending the history of Asian monsoon across the desert regions of the modern Asian monsoonal margin in northern China.
基金supported by Chinese Polar Environment Comprehensive Investigation&Assessment Programs(Grant nos.CHINARE2017-02-01,CHINARE2017-04-04)
文摘Palaeo-notch sediment, accumulated in lacustrine environment, is a reliable proxy material for palaeoclimatic and palaeoenvironmental research. In this study, we collected a palaeo-notch sediment profile from the Blomstrandhalv?ya, used multiple geochemical proxies to reconstruct palaleoproductivity variations, and investigated their link to climatic records from surrounding regions. C/N atomic ratios and carbon isotope indicate that organic matter in the sediment is mainly derived from lacustrine algae. Toward the surface sediment, the TOC, TN, P contents and the reconstructed palaeoproductivity show remarkable fluctuations with several peaks and troughs, opposite to the variation trend of the CaCO3 contents. Changes in the reconstructed palaeoproductivity are in good agreement with palaeoclimatic records from the surrounding regions, and three interruptions are likely linked to the well-known cooling periods around 1900 BP, 2800 BP and 4200 BP. Thus palaeoproductivity variations on the Blomstrandhalv?ya are mainly driven by climate changes; palaeoproductivity increase during warmer periods, and vice versa. This study will help the research of Arctic lake ecosystem and its response to climate change.
文摘淮河流域特大暴雨洪水灾害严重威胁经济社会发展,其防洪减灾和水资源开发利用,急需超长时间尺度河流洪水水文学数据资料的支撑。全新世古洪水水文学的研究,为淮河流域全新世洪水水文数据发掘提供了重要途径。利用河流地貌学、沉积学、水文学和年代学等多学科交叉的方法,获取淮河中上游全新世万年来实际发生过的特大暴雨洪水事件的沉积学记录,采用多种水文模型模拟恢复与检验,获得古洪水事件的洪峰水位和流量数据。淮河干流桐柏东段基岩峡谷的研究发现,过去10 000 a以来发生多次特大洪水事件,尤其是发生在3.1 ka B.P.和1.5 ka B.P.时期的古洪水事件,洪峰水位最高,洪峰流量可达14 300~16 000 m^(3)/s,淮河支流汝河遂平段的调查研究和测年断代表明,在(12.0-11.2) ka B.P.、(4.2-4.0) ka B.P.和(3.2-3.0) ka B.P.,分别发生过3期古洪水事件。而支流沙河在(1.45-1.55) ka B.P.发生过特大泛滥洪水事件,对应于中国历史上南北朝时期的严重气候恶化阶段。这些时段处在全球性气候事件、气候恶化或气候转折阶段。在这些时段,季风状态极其不稳定,变率增大,导致气候异常,极端性变化频繁,既有严重干旱,又有特大洪水事件发生。因此,在全新世来说,淮河流域特大暴雨洪水事件并不必然的与温暖湿润气候阶段相联系。这些研究丰富了高分辨率气候水文事件的内涵,对于深刻理解区域气候水文系统对于全球变化的响应规律具有重要的科学意义。
基金supported by the National Natural Science Foundation of China(Grant No.40172013).
文摘Middle Permian palaeo-seamounts in the area of Bayan Har are generally com-posed of volcanic basement and carbonate cap. Basaltic lava, volcanic breecia and polymictic breccia can be identified as the main kinds of rock in the basement of palaeo-seamounts. Mas-sive bioclastic limestone and reef framestone formed the carbonate cap of the palaeo-sea- mounts. The contact relationship between carbonate cap and volcanic basement is a kind of conformity or depositional unconformity. Study of the structure and petrology of palaeo-sea- mounts suggests that the evolution history of the palaeo-seamounts in this area can be divided into five stages at least. They are the origin of the first volcanic basement, the formation of the first carbonate cap, the breaking of the first carbonate cap by renewed volcanism, the deposition of red calcareous mudstone and the rebuilding of the second carbonate cap at last. In one of the palaeo-seamounts, volcanic activation took place even after the reconstruction of the second carbonate cap. Lots of fusulinid fossils, such as Neoschwagerina craticulifera Schwager, Schwagerina sp. and Verbeekina sp., were found both in the carbonate cap and volcanic base-ment, showing that the palaeo-seamounts were originated and developed within the Maokou stage of Middle Permian.
文摘The palaeo-forest vestige has been found for the first time on the sea floor of Shenhuwan Gulf, Jinjiang County, Fujian Province (N24°38′, E118°39′) during my seismic investigation in July, 1986.
文摘The Nansha sea area is located in the place where the Pacific Ocean plate, In-dian-Australian plate and Eurasian plate meet, and therefore, its formation and evolu-tion are both constrained by those three plates. It is a semi-closed marginal sea area,which is only connected with the Indian and the Pacific Ocean by channels. TheSr-O isotopic composition of sediments in this area was systematically studied for fur-ther understanding of its formation and evolution. The range of our investigation islimited to the area of 105-118°E and 3 - 12°N. The surface sediments from 36 sta-tions, which are distributed in the above area, were analyzed. All of the
文摘黄河流域古河道的变迁对文化遗址形成的影响,是黄河文化研究的重要科学问题之一。内蒙古巴彦淖尔国家地质公园位于黄河中上游的河套盆地,公园内汉代临戎古城遗址的位置一直存在争论,确定黄河古河道与其相对位置关系是关键。通过对临戎古城遗址周边10 km范围进行网格化槽型钻取心,利用钻孔数据构建三维粒度属性模型与沉积结构模型,对隐伏的古河道位置进行了较为精准地确定;并通过钻孔岩心沉积相分析与年代学测试,对古河道的沉积结构与年代进行了验证。结果表明,临戎古城遗址西3 km处存在(2.39±0.24) ka~(1.36±0.05) Cal ka BP的黄河古河道,自南向北流经临戎城西。以此确定的黄河与朔方郡各属县治城的相对位置符合史料的记载。本研究从沉积学角度为巴彦淖尔国家地质公园临戎古城遗址位置的考证提供了地质科学依据。
