The northeastern margin of the Tibetan Plateau is the youngest part of the Tibetan Plateau where tectonic activity is intense and climate change is complex.In this study,combined with field investigations,we explored ...The northeastern margin of the Tibetan Plateau is the youngest part of the Tibetan Plateau where tectonic activity is intense and climate change is complex.In this study,combined with field investigations,we explored accelerator mass spectrometry 14C and optically stimulated luminescence dating and palynological analysis of the sedimentary sequence in the Qingshuihe Basin to explain the origin of soft-sediment deformation layer.Dating and palynological results from the Sanchahe section in the basin revealed a detailed history of vegetation variation and associated climate change from~18 to~5 ka BP.The results indicate that the permafrost developed at~18–11.7 ka BP,and the soft-sediment deformation structures formed at~11.7–5 ka BP.Together with the characteristics of the deformation(meter-scale,continuous symmetrical wave)and paleoclimate,we suggest that the soft-sediment deformation layer in the late Pleistocene was cryoturbated under climatic conditions.The discovery of a series of cryoturbations in the Qingshuihe Basin has further enriched the regional distribution of periglacial phenomena in the west of the Ordos Plateau,expanded the distribution range of periglacial phenomena,and provided evidence for exploring the temporal and spatial changes in permafrost in northern China at the end of the late Pleistocene.展开更多
The Tibetan Plateau is an important area for studying global climate change,but the answers to many scientific problems remain unknown.Here,we present new information from the lacustrine sedimentary record in the west...The Tibetan Plateau is an important area for studying global climate change,but the answers to many scientific problems remain unknown.Here,we present new information from the lacustrine sedimentary record in the western Tibetan Plateau,related to the third most-recent glaciations.Continuous sediment data,including sporopollen,particle size,total organic carbon,mass susceptibility,CaCO_(3),CaSO_(4),BaSO_(4)contents and chronological data,were reconstructed and revealed that climate and environmental conditions obviously and distinctly changed between 600 and 700 thousand years ago.In comparison,the data obtained from the Guliya ice core in this area also corresponds to the global glacial climatic characteristics recorded in basin sediments in the eastern and southeastern regions of the plateau and to the information obtained from ice cores in the Antarctic and Arctic regions.In this study,we conclude that the main reason for the glaciations and new tectonic movement must be a geomagnetic polarity reversal 774 thousand years ago(from Matuyama to Brunhes).Indeed,the results of this study suggest that the described reversal event might have influenced the current global climate pattern and will continue to impact climatic changes in the future.展开更多
There are three transgression-regression events and evolutions of the sedimentary environment by sea level changes since the Pleistocene in the southern section of the Bohai Sea, China. It is obvious that a multi-sour...There are three transgression-regression events and evolutions of the sedimentary environment by sea level changes since the Pleistocene in the southern section of the Bohai Sea, China. It is obvious that a multi-source fluvial delta sedimentary system may be more dominant in a sedimentary environment. Based on previous research and survey or historical data, we carried out studies on the division of sedimentary units, sedimentary facies analysis and strata division and comparison, which aim to establish the sedimentary stratigraph of Laizhou Bay. We focus on the sedimentary procession of the Laizhou Bay since the early Late Pleistocene. It can be divided into two glacial periods and three interglacial periods, corresponding to two regression and three transgression events in Laizhou Bay since Late Pleistocene. In 124.6-72.0 ka BP, 60.0-24.4 ka BP and 10.2-4.0 ka BP, three times warm-wet periods occurred, respectively corresponding to the Cangzhou transgression, Xianxian transgression, and Huanghua transgression. In 72.0-60.0 ka BP and 24.4-10.2 ka BP, two dry and cold periods, it was the continental sedimentary environment, corresponding to Wurm early glacier and Wurm late glacier. The results show:(1) Sediments have the characteristics of phase and stage under the terrestrial input of the Yellow River and middle-small rivers in the southern section of the Bohai Sea.(2) PI moved towards coastal in Cangzhou transgression strata in early Late Pleistocene. PI moved northward from land in Xianxian transgression strata in the late Pleistocene. PI moved further north in the Huanghua transgression strata in Holocene.(3) During the regressive period, the land source input increased and the estuarine or lagoon sedimentation developed, which manifested as progradational superposition.(4) During the transgressive period, it mainly developed shallow coastal sediment and transitionally formed regressive deposition to the south in delta/tidal flat deposition.展开更多
In the later stage of Late Pleistocene, global climate entered into the climax period of Wurm when temperature decreased remarkably and glaciers developed. Information from the East China Sea also confirm that the sea...In the later stage of Late Pleistocene, global climate entered into the climax period of Wurm when temperature decreased remarkably and glaciers developed. Information from the East China Sea also confirm that the sea level fell by at least 130 m at that time (Emery, 1968). The Bohai Sea and Yellow Sea at the climax period were totally exposed, while the East China Sea and South China Sea shelf regions were exposed partly. The exposed shelf area exceeded 1 million km2 and became a salty desert where land plants could not survive. Such were the conditions which led to the desertization of the shelf region.Eolation was the major exogenetic force not only on land but also on the shelf region in the ice age. At the climax period of Wiirm, the northern part of China developed thick layers of loess deposits. The shelf region at that time had similar climatic conditions and sediments. Because the shelf region was not protected by vegetation in the ice age, intensive wind storms remoulded the primarily展开更多
The 'Old Red Sand' is a type of semicemented medium-fine sandy sediment that is red(10R_4/8) or brown red(2.5YR_4/8) in colour and is found in late Quaternary deposits. The sediments have distinctive character...The 'Old Red Sand' is a type of semicemented medium-fine sandy sediment that is red(10R_4/8) or brown red(2.5YR_4/8) in colour and is found in late Quaternary deposits. The sediments have distinctive characteristics and are a critical archive for understanding climatic changes in the coastal areas of East Asia. The ages of the late Quaternary aeolian sand dunes from Haitan Island in the coastal area of South China are still in debate. In this study, three sets of marine terraces were identified in the northern region of Haitan Island. Aeolian dune sands are well preserved on the top of these terraces. Quartz Optically Stimulated Luminescence dating and the distribution of the formation ages demonstrated that the palaeo-dunes are deposits from the middle-late period of the Late Pleistocene(Q_3^(2-3)). The period may be divided into three stages, 100-90 ka, 70-60 ka, and 40-20 ka, in which the palaeo-dunes of the first two stages are more widespread and were formed separately during a low-sea level period of the Marine Isotope Stages 5 b and 4. Several depositional palaeo-flood event records were preserved during the last stage due to the increasing gradient of mountain gullies formed during the Last Glacial Maximum.展开更多
Geochemistry analysis has been done on Core E (37 07’ N, 118 55’ E; depth: 82.1 m) taken from the Laizhou Bay in 1994. Nine kinds of invariable elements, 15 kinds of microelements and the content of lime carbonate a...Geochemistry analysis has been done on Core E (37 07’ N, 118 55’ E; depth: 82.1 m) taken from the Laizhou Bay in 1994. Nine kinds of invariable elements, 15 kinds of microelements and the content of lime carbonate are measured by means of ICP. The results indicate that most of the invariable elements and microelements in Core E show significant changes in the boundary stratotype, and the ratios between elements (Mn/Fe, Sr/Ba, Ti/Al) in particular. So they can be used as characteristic indicator to stratigraphic division of Quaternary. The changes of invariable elements are primarily controlled by the host minerals, and they mainly indicate the provenance as well as the sedimentation and depositional environment. Several elements, such as Fe, Al, Ca, Mg, Mn and Ti, are very sensitive to the provenance and environment. The distribution of microelements differs in four depositional periods: last stage of Middle Pleistocene, last interglacial period, last glacial period and Recent epoch, and especially in the "cold period" and "warm period". The loops in the cycle curves of the most microelements correspond with the sand bed sediments, among which there are six sand units representing "warm period" sediments, and one representing "cold period" sediments. The carbonate is on the high side in the aeolian silt sediments formed in the glacial lowering of sea level in Core E, but on the low side in the transgressive sand beds formed in the interglacial period. The content variation of carbonate has a direct bearing on the grain size and the styles of sediments, and is a good indicator to the climate, environment and stratigraphic division.展开更多
Lithological,geochronological,granulometric,and scanning electron microscope(SEM)analyses of eight lacustrine outcrops indicate the existence of a large palaeolake in Dali Nor area during 149-24.6 ka(MIS5-3)and a smal...Lithological,geochronological,granulometric,and scanning electron microscope(SEM)analyses of eight lacustrine outcrops indicate the existence of a large palaeolake in Dali Nor area during 149-24.6 ka(MIS5-3)and a small one in upstream of the Xilamulun River during 12.96-11.69 ka.The large palaeolake recorded its highest water level above 1300 m during the MIS3 and covered the whole Dali Nor basin and upstream of the Xilamulun River within an area of about 3000 km^2.However,the small palaeolake with a highest water level above 1200 m,covered an area of about 600 km^2.Besides the reconstruction of palaeolake areas,this study also looked into the evolutionary process of the palaeolake during the Late Pleistocene.Our data provide insights on the timing of appearance of the large palaeolakes and a better understanding of the mechanism responsible for variations in the environment conditions of dry lands in middle latitudes.展开更多
Based on the evidences of lithostratigraphy, palynology, micropaleontolopy and geochronology, paleoenvironments since the Late Pleistocene in the study area have been reconstructed. One of the most important inference...Based on the evidences of lithostratigraphy, palynology, micropaleontolopy and geochronology, paleoenvironments since the Late Pleistocene in the study area have been reconstructed. One of the most important inferences is that two marine transgressions have occurred, one in Wurm Sub-interglacial and the other Postglacial. The former had caused the study area to be in an estuary-bay envirment over the transgression maximum, with a sea level of no less than 10 m below present; foe latter reached its maximum over the Atlantic stage, with sedimentary environments of estuary-bay, hay or shallow sea, and the sea level arrived at the highest elevation in about 6 - 5 ka B.P. Furthermore, it is notable that, during the Late Wurm Glacial, the study area area had principally been in an estuary-bay environment, although the climate, like many other areas, turned cold and dry, It reflects a general trend of crustal subduction in Jiulong Estudrine Plain over this pened.展开更多
Signal processing techniques of cross-correlation, power spectral analysis and cross-power spectral analysis are used to determine the relationships between paleomagnetic properties and the oxygen isotope record of th...Signal processing techniques of cross-correlation, power spectral analysis and cross-power spectral analysis are used to determine the relationships between paleomagnetic properties and the oxygen isotope record of the South China Sea during the late Pleistocene. On the basis of correlation tests between the δ18O time series of cores V3 and A15 with the paleomagnetic properties of core SCS01, five events of susceptibility and intensity of natural remanent magnetization are identified as glacial events corresponding to δ18O positive events. The magnetic properties of the sediments which are independent of the geomagnetic field are sensitive climatic indicators which have frequencies corresponding to the Milankovitch orbital parameters.展开更多
The Quaternary sediments in the Yili Basin can serve as archives for studying the Cenozoic basin-mountain relationship. In this study, based on typical natural sections and boreholes, the surficial sediments of the Hu...The Quaternary sediments in the Yili Basin can serve as archives for studying the Cenozoic basin-mountain relationship. In this study, based on typical natural sections and boreholes, the surficial sediments of the Huocheng area were studied, and their sedimentary ages were obtained using the optically stimulated luminescence(OSL) and electron spin resonance(ESR) dating methods. These dates, combined with changes in the sedimentary facies, provided details of the neotectonic movement in the Yili Basin and adjacent areas. By dating sediments from five sections and three boreholes, we determined that the surficial sediments of the Huocheng area were mainly formed in the Late Pleistocene, with scattered instances of Holocene sediments. The surficial sediments mainly consisted of alluvial fan facies, fluvial facies, lacustrine facies, and desert facies. Based on the activity on the Hongshanzui fault and the northern margin fault of the Wusun Mountains, the Huocheng area was uplifted synchronously with the Tianshan Mountains during the last stage of the Late Pleistocene, causing the desert facies sediments to be superimposed on the former paleo-lake sediments.展开更多
In 1999, Diexi paleo-dammed lake(2349 m a.s.l.) was discovered around Diexi town along the Minjiang River in Sichuan province. Diexi is located where the eastern edge of the Tibetan Plateau and the Sichuan Basin meet....In 1999, Diexi paleo-dammed lake(2349 m a.s.l.) was discovered around Diexi town along the Minjiang River in Sichuan province. Diexi is located where the eastern edge of the Tibetan Plateau and the Sichuan Basin meet. The dammed lake was formed during the Last Glacial Maximum of the Late Pleistocene(~30,000 years ago) and began to empty about 15,000 years ago. The lacustrine sediments(up to 240 m thick) preserve abundant paleoenvironment information. In this paper, a mass of oxygen isotopes and 14 C dating from drilled cores are analyzed and discussed. The δ18 O curve on the paleo climate from this section is comparable with the coeval paleo climatic curves of ice cores and karsts in China and others. Furthermore, the physical model testing has confirmed that the disturbed zones in the core are caused by strong earthquakes occurred at least 10 times, which implies strong crustal deformation, as an important driving force, affecting climate change. This study provides a new window to observe East Asian monsoon formation, paleoenvironmental evolution and the global climate change.展开更多
The Rhinocerotidae is one of the most common and important families in the Pleistocene mammalian fauna of South China.Since the last century,most of the Pleistocene rhinocerotid fossils were prematurely assigned to Rh...The Rhinocerotidae is one of the most common and important families in the Pleistocene mammalian fauna of South China.Since the last century,most of the Pleistocene rhinocerotid fossils were prematurely assigned to Rhinoceros sinensis,which has resulted in confusion of taxonomy for decades,especially in South China.The Yanjinggou area in Chongqing Municipality of China,where the neotype of R.sinensis came from,has yielded abundant rhinocerotid fossils and is a key area to solve this problem.A recently discovered juvenile skull from a karstic fissure in this area can be referred to Dicerorhinus sumatrensis(Fischer,1814),which is the first confirmed non-Rhinoceros rhinocerotid from the area.This new finding indicates that non-Rhinoceros fossils might have been mixed in AMNH collection from Yanjinggou and thus the diagnosis of Rhinoceros sinensis needs reformation.On the other hand,Stephanorhinus?kirchbergensis is also detected in Granger’s collection based on our reobservation.The coexistence of Rhinoceros,Dicerorhinus and Stephanorhinus shows the higher diversity of Pleistocene rhinocerotids in South China.展开更多
Fifteen basaltic rock samples were collected from central Jordan at the Atarous volcanism basaltic flow area. The samples cover about 8 km2 from the Atarous Basalt flow (AB). The AB flow was introduced in the Miocene ...Fifteen basaltic rock samples were collected from central Jordan at the Atarous volcanism basaltic flow area. The samples cover about 8 km2 from the Atarous Basalt flow (AB). The AB flow was introduced in the Miocene to Pleistocene periods. The samples analyze major and trace elements by using XRF. Petrography, Geochemistry and Petrogensis have investigation to carried out for the AB. The petrography analyses of the AB rocks show they are composed of plagioclase (labradorite and bytownite), pyroxene (augite), and olivine (forsterite);accessory minerals include apatite and secondary minerals magnetite, ilmenite, spinel and iddingsite. The AB is classified within alkaline to sub-alkaline and tholeiitic to Calc-Alkaline basalt. The Mg# range between 0.39 and 0.49 of basalt samples exhibits different degrees of fractionation with a low degree of melting < 15% as indicated from the varying concentration of incompatible trace elements Ba, Rb, Sr. Trace elements of primary magna show low variable abundances of compatible and incompatible elements, which reflecs a homogenous source. Geochemical parameters such as Mg# and high Ti contents indicate that the corresponding magmas are of primary origin. The tectonic setting of AB is explained by using discrimination diagrams, Ti-Zr-Sr and Nb-Zr-Y and Ti-Zr-Y, the AB plotted within the plate basalt, alkali basalt and Calk alkaline basalt field, respectively. The spider diagram shows the samples AB enrichment of the Ba, K, Nb and Ce, depletion of Nb and Y. The AB exhibited positive Nb, Ce and Ti anomalies, and negative anomalies of Ba, Sr, and P. It is attributed to the fractionation of feldspar for Ba and Sr and apatite for P depletion. The spider diagram showed a positive Nb peak, which conforms to the tertiary and to recent continental alkali basalt provinces and indicates that the AB is the product of lithosphere from upwelling asthenosphere mantle.展开更多
A marine stratigraphic sequence across the Pliocene / Pleistocene boundary has been found in the north-ern continental shelf of the South China Sea. The marine Quaternary deposits in the Yinggehai Basin may ex-ceed 2,...A marine stratigraphic sequence across the Pliocene / Pleistocene boundary has been found in the north-ern continental shelf of the South China Sea. The marine Quaternary deposits in the Yinggehai Basin may ex-ceed 2,000 m in thickness, probably providing the best section for studying the lower boundary of the marinePleistocene in South China. The vertical succession with planktonic foraminifers and nannofossils revealed inboreholes in the basin has been well correlated with that in the international stratotype section of thePliocene / Pleistocene boundary at Vrica, Italy, resulting in the acquirement of a biostratigraphic boundary at1.64 Ma. This boundary, however, does not coincide with any prominent lithological palaeoenvironmentalchanges in the study area and can hardly be used in geological practice. There are, in contrast, significantchanges at the level of LAD of Globorotalia multicamerata sensu lato located below the above-mentionedboundary. The percentage of planktonic foraminifers in the total population and preservation of foraminiferaltests display great changes at this level corresponding to a clear onlap on the seismic profiles and indicating adepositional hiatus at ca. 2.0-2.5 Ma. Since the level can be widely traced in the Pearl River Mouth Basin andthe Beibu Gulf Basin and well corresponds with the marked depositional environmental changes recorded inthe west Pacific and other regions, it is recommended that the Plio / Pleistocene boundary be drawn at the levelof Gr. multicamerata sensu lato LAD, roughly concurrent with the Gauss / Matuyama turn.展开更多
The environmental changes during the Late Pleistocene were more obvious in the eastern China than in other areas at the same latitude, which either between northern and southern, or between land and sea of the eastern...The environmental changes during the Late Pleistocene were more obvious in the eastern China than in other areas at the same latitude, which either between northern and southern, or between land and sea of the eastern China were mostly non-synchronous. The transitional period prior to the last glaciation came about in the northern part of the eastern China about 115,000 yr. ago. The desert environments of the inland of the north China were developed both in the glacial maximum and in the warm interglacial period, but the loess accumulation mostly took place during the glacial period. The sand dunes and the periglacial solifluctions in the lower Changjiang (Yangtze) River region were formed during the last glacial period. The event of lowest surface temperature occurred at 98,000 yr. B.P. and 59,000 yr. B.P. in the northern part of the South China Sea but not during the full-glacial stage. The phenomena mentioned . above were the result of the following reasons that the paleo-environmental changes in展开更多
Tibet is the largest and highest plateau on the Earth (having 82% of the world’s land surface area falling >4km above sea level) attributed to the India and Asian convergence tectonics. Recently, high\|resolution ...Tibet is the largest and highest plateau on the Earth (having 82% of the world’s land surface area falling >4km above sea level) attributed to the India and Asian convergence tectonics. Recently, high\|resolution digital topography data (Fielding et al., 1994) confirmed the earlier observations about flat erosional surfaces in the central part of the plateau (Jujin, et al., 1995) and suggested extraordinary flatness at a wide range of scales. Much of the Tibetan plateau across different accreted terranes has shallow slopes between 5°～10° and variation in relief of about 1 km, except in its marginal parts (Himalayan ranges; Kunlun mountains) where rough and high topography with intense fluvial dissections (variations in relief up to 7km) is quite frequent. However, in the southern and south\|central part of the plateau along the Pliocene\|Quaternary grabens, slopes generally steepen.展开更多
A complex history of the Late Pleistocene vegetation and environmental changes for the northern part of the deciduous forest is revealed in an exceptionally well dated pollen diagram from Dongganchi in Beijing area. I...A complex history of the Late Pleistocene vegetation and environmental changes for the northern part of the deciduous forest is revealed in an exceptionally well dated pollen diagram from Dongganchi in Beijing area. In 15?800- 14?700 a B.P., the arbors and aquatic plants were sparse, and the climate was cold and dry. In 14 700-13?400 a B.P., forest growth was limited, it was dominated by conifers, presumably in responded to a cooling climate. Aquatic plants became abundant. During 13?400 to 12?600 a B.P., there was a widespread development of coniferous and broad leaved mixed forest, aquatic plants decreased which corresponded to climate gradually becoming warming and dry. In 12?600-11?400 a B.P., there was alternation of coniferous and broad leaved mixed forest, so were aquatic plants. From 11?400 to 9?600 a B.P., the decreasing of trees and increasing of herbs and shrubs suggested an opening up of the vegetation in responded to cooling, probably corresponded to Younger Dryas from 10?600 to 10?300 a B.P. About 9600-7270 a B.P., the climate changed from cooler and dry to warmer and humid. About 7270-3390 a B.P., the coniferous and the broad leaved mixed forest increased, it was in responding to the “climatic optimum". About 3390-1000 a B.P., climate became cooler and dry. After 1000 a B.P., there was a severe fluctuation, indicating the temperature drop and the environmental deterioration.展开更多
The Casablanca region is world famous for its fossil sites,ranging from the Mio-Pliocene to the Holocene. The"gazelles cave"at Tamaris I in the region of Casablanca(Morocco),was recently discovered during co...The Casablanca region is world famous for its fossil sites,ranging from the Mio-Pliocene to the Holocene. The"gazelles cave"at Tamaris I in the region of Casablanca(Morocco),was recently discovered during construction work.It forms a pocket,cut into the marine calcarenite of the A(i|¨)n Roumman Member and is filled with continental sediments(Lahlalfa member) of Upper Pleistocene age.The fauna is largely dominated by gazelles,hence the name given to this locality.Ankle bones discovered at the展开更多
This study deals with the relationship between sea-level changes and paleoclimatic fluctuations based on the analysis of stratigraphy, grain sizes, palynology, and radiometric dating of the Yellow River delta since th...This study deals with the relationship between sea-level changes and paleoclimatic fluctuations based on the analysis of stratigraphy, grain sizes, palynology, and radiometric dating of the Yellow River delta since the Late Pleistocene. Evidence from the sedimentary record, grain sizes, and pollen provides a paleoenvironmental history of the Late Pleistocene from the boreholes of the delta. Based on a combination of grain-size analysis with lithological studies, marine deposit units contain the intervals of 13.85–16.9, 18.5–19.69, 27.9–34.8, 36.4–37.2, 48.4–51.6, and 54.1–55.9 m, and transitional facies units contain the intervals of 10.25–13.85, 16.9–18.5, 19.69–27.9, 34.8–36.4, 37.2–48.4, 51.6–54.1, and 55.9–60 m, compared with fluvial(terrestrial facies) deposit units(3.36–10.25 m). Based on pollen analysis and pollen assemblages, there were three warm-wet periods from 9.1–0.16 ka BP, 16.1–60 ka BP, and 90.1–94.6 ka BP From the top to the bottom of the borehole, the paleoclimate has an evident fluctuation: warm and moist(Holocene Optimum) —cool and dry(Younger Dryas Event)—mild semi cool—cool and dry—warm and moist. There were three warm-wet periods from 9.1–0.16 ka BP, 16.1–60 ka BP, and 90.1–94.6 ka BP, corresponding to the Holocene Optimum stage, MIS 3, and MIS 5, respectively. The warm period allowed monsoonal evergreen and broadleaved deciduous forests that corresponded to Holocene hypsithermal climatic conditions and the Late Pleistocene climatic Optimum. Three warm-wet periods occurred in marine deposit units from 9.1–0.16 ka BP, 60.1–16.1 ka BP, and 94.6–90.1 ka BP. These periods correspond to the Cangzhou transgression, Xianxian transgression, and Huanghua transgression, respectively. From 90.1–60.1 ka BP, 17.5–9.1 ka BP, and 0. 16 ka BP–1855 AD, three dry and cold phases are recognized. The phases indicate the fluvial(flood plain) sedimentary environment, corresponding to cooler and mild dry periods based on palynological results and grain-size distribution.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.41972119)the Geological Investigation Project of the China Geological Survey(Grant Nos.DD20190018 and DD20221644)。
文摘The northeastern margin of the Tibetan Plateau is the youngest part of the Tibetan Plateau where tectonic activity is intense and climate change is complex.In this study,combined with field investigations,we explored accelerator mass spectrometry 14C and optically stimulated luminescence dating and palynological analysis of the sedimentary sequence in the Qingshuihe Basin to explain the origin of soft-sediment deformation layer.Dating and palynological results from the Sanchahe section in the basin revealed a detailed history of vegetation variation and associated climate change from~18 to~5 ka BP.The results indicate that the permafrost developed at~18–11.7 ka BP,and the soft-sediment deformation structures formed at~11.7–5 ka BP.Together with the characteristics of the deformation(meter-scale,continuous symmetrical wave)and paleoclimate,we suggest that the soft-sediment deformation layer in the late Pleistocene was cryoturbated under climatic conditions.The discovery of a series of cryoturbations in the Qingshuihe Basin has further enriched the regional distribution of periglacial phenomena in the west of the Ordos Plateau,expanded the distribution range of periglacial phenomena,and provided evidence for exploring the temporal and spatial changes in permafrost in northern China at the end of the late Pleistocene.
基金supported by grants from the China Geological Survey(Grant Nos.1212010610102,DD20190065).
文摘The Tibetan Plateau is an important area for studying global climate change,but the answers to many scientific problems remain unknown.Here,we present new information from the lacustrine sedimentary record in the western Tibetan Plateau,related to the third most-recent glaciations.Continuous sediment data,including sporopollen,particle size,total organic carbon,mass susceptibility,CaCO_(3),CaSO_(4),BaSO_(4)contents and chronological data,were reconstructed and revealed that climate and environmental conditions obviously and distinctly changed between 600 and 700 thousand years ago.In comparison,the data obtained from the Guliya ice core in this area also corresponds to the global glacial climatic characteristics recorded in basin sediments in the eastern and southeastern regions of the plateau and to the information obtained from ice cores in the Antarctic and Arctic regions.In this study,we conclude that the main reason for the glaciations and new tectonic movement must be a geomagnetic polarity reversal 774 thousand years ago(from Matuyama to Brunhes).Indeed,the results of this study suggest that the described reversal event might have influenced the current global climate pattern and will continue to impact climatic changes in the future.
文摘There are three transgression-regression events and evolutions of the sedimentary environment by sea level changes since the Pleistocene in the southern section of the Bohai Sea, China. It is obvious that a multi-source fluvial delta sedimentary system may be more dominant in a sedimentary environment. Based on previous research and survey or historical data, we carried out studies on the division of sedimentary units, sedimentary facies analysis and strata division and comparison, which aim to establish the sedimentary stratigraph of Laizhou Bay. We focus on the sedimentary procession of the Laizhou Bay since the early Late Pleistocene. It can be divided into two glacial periods and three interglacial periods, corresponding to two regression and three transgression events in Laizhou Bay since Late Pleistocene. In 124.6-72.0 ka BP, 60.0-24.4 ka BP and 10.2-4.0 ka BP, three times warm-wet periods occurred, respectively corresponding to the Cangzhou transgression, Xianxian transgression, and Huanghua transgression. In 72.0-60.0 ka BP and 24.4-10.2 ka BP, two dry and cold periods, it was the continental sedimentary environment, corresponding to Wurm early glacier and Wurm late glacier. The results show:(1) Sediments have the characteristics of phase and stage under the terrestrial input of the Yellow River and middle-small rivers in the southern section of the Bohai Sea.(2) PI moved towards coastal in Cangzhou transgression strata in early Late Pleistocene. PI moved northward from land in Xianxian transgression strata in the late Pleistocene. PI moved further north in the Huanghua transgression strata in Holocene.(3) During the regressive period, the land source input increased and the estuarine or lagoon sedimentation developed, which manifested as progradational superposition.(4) During the transgressive period, it mainly developed shallow coastal sediment and transitionally formed regressive deposition to the south in delta/tidal flat deposition.
基金Project sponsored by the National Natural Science Foundation of China
文摘In the later stage of Late Pleistocene, global climate entered into the climax period of Wurm when temperature decreased remarkably and glaciers developed. Information from the East China Sea also confirm that the sea level fell by at least 130 m at that time (Emery, 1968). The Bohai Sea and Yellow Sea at the climax period were totally exposed, while the East China Sea and South China Sea shelf regions were exposed partly. The exposed shelf area exceeded 1 million km2 and became a salty desert where land plants could not survive. Such were the conditions which led to the desertization of the shelf region.Eolation was the major exogenetic force not only on land but also on the shelf region in the ice age. At the climax period of Wiirm, the northern part of China developed thick layers of loess deposits. The shelf region at that time had similar climatic conditions and sediments. Because the shelf region was not protected by vegetation in the ice age, intensive wind storms remoulded the primarily
基金funded by the National Natural Science Foundation of China (Grants Nos. 41301012, 41771020 and U1405231)Natural Science Foundation of Fujian (Grant No. 2018R1034-5)Innovation Research Team Fund of Fujian Normal University (Grant No. IRTL1705)
文摘The 'Old Red Sand' is a type of semicemented medium-fine sandy sediment that is red(10R_4/8) or brown red(2.5YR_4/8) in colour and is found in late Quaternary deposits. The sediments have distinctive characteristics and are a critical archive for understanding climatic changes in the coastal areas of East Asia. The ages of the late Quaternary aeolian sand dunes from Haitan Island in the coastal area of South China are still in debate. In this study, three sets of marine terraces were identified in the northern region of Haitan Island. Aeolian dune sands are well preserved on the top of these terraces. Quartz Optically Stimulated Luminescence dating and the distribution of the formation ages demonstrated that the palaeo-dunes are deposits from the middle-late period of the Late Pleistocene(Q_3^(2-3)). The period may be divided into three stages, 100-90 ka, 70-60 ka, and 40-20 ka, in which the palaeo-dunes of the first two stages are more widespread and were formed separately during a low-sea level period of the Marine Isotope Stages 5 b and 4. Several depositional palaeo-flood event records were preserved during the last stage due to the increasing gradient of mountain gullies formed during the Last Glacial Maximum.
基金This study was supported by the National Natural Science Foundation of China under contract Nos 49776296 and 49894170.
文摘Geochemistry analysis has been done on Core E (37 07’ N, 118 55’ E; depth: 82.1 m) taken from the Laizhou Bay in 1994. Nine kinds of invariable elements, 15 kinds of microelements and the content of lime carbonate are measured by means of ICP. The results indicate that most of the invariable elements and microelements in Core E show significant changes in the boundary stratotype, and the ratios between elements (Mn/Fe, Sr/Ba, Ti/Al) in particular. So they can be used as characteristic indicator to stratigraphic division of Quaternary. The changes of invariable elements are primarily controlled by the host minerals, and they mainly indicate the provenance as well as the sedimentation and depositional environment. Several elements, such as Fe, Al, Ca, Mg, Mn and Ti, are very sensitive to the provenance and environment. The distribution of microelements differs in four depositional periods: last stage of Middle Pleistocene, last interglacial period, last glacial period and Recent epoch, and especially in the "cold period" and "warm period". The loops in the cycle curves of the most microelements correspond with the sand bed sediments, among which there are six sand units representing "warm period" sediments, and one representing "cold period" sediments. The carbonate is on the high side in the aeolian silt sediments formed in the glacial lowering of sea level in Core E, but on the low side in the transgressive sand beds formed in the interglacial period. The content variation of carbonate has a direct bearing on the grain size and the styles of sediments, and is a good indicator to the climate, environment and stratigraphic division.
基金supported by the National Natural Science Foundation of China(Grant No.41320003)Special Research of the Ministry of Land and Resources,China(Grant No.20121107703)
文摘Lithological,geochronological,granulometric,and scanning electron microscope(SEM)analyses of eight lacustrine outcrops indicate the existence of a large palaeolake in Dali Nor area during 149-24.6 ka(MIS5-3)and a small one in upstream of the Xilamulun River during 12.96-11.69 ka.The large palaeolake recorded its highest water level above 1300 m during the MIS3 and covered the whole Dali Nor basin and upstream of the Xilamulun River within an area of about 3000 km^2.However,the small palaeolake with a highest water level above 1200 m,covered an area of about 600 km^2.Besides the reconstruction of palaeolake areas,this study also looked into the evolutionary process of the palaeolake during the Late Pleistocene.Our data provide insights on the timing of appearance of the large palaeolakes and a better understanding of the mechanism responsible for variations in the environment conditions of dry lands in middle latitudes.
文摘Based on the evidences of lithostratigraphy, palynology, micropaleontolopy and geochronology, paleoenvironments since the Late Pleistocene in the study area have been reconstructed. One of the most important inferences is that two marine transgressions have occurred, one in Wurm Sub-interglacial and the other Postglacial. The former had caused the study area to be in an estuary-bay envirment over the transgression maximum, with a sea level of no less than 10 m below present; foe latter reached its maximum over the Atlantic stage, with sedimentary environments of estuary-bay, hay or shallow sea, and the sea level arrived at the highest elevation in about 6 - 5 ka B.P. Furthermore, it is notable that, during the Late Wurm Glacial, the study area area had principally been in an estuary-bay environment, although the climate, like many other areas, turned cold and dry, It reflects a general trend of crustal subduction in Jiulong Estudrine Plain over this pened.
文摘Signal processing techniques of cross-correlation, power spectral analysis and cross-power spectral analysis are used to determine the relationships between paleomagnetic properties and the oxygen isotope record of the South China Sea during the late Pleistocene. On the basis of correlation tests between the δ18O time series of cores V3 and A15 with the paleomagnetic properties of core SCS01, five events of susceptibility and intensity of natural remanent magnetization are identified as glacial events corresponding to δ18O positive events. The magnetic properties of the sediments which are independent of the geomagnetic field are sensitive climatic indicators which have frequencies corresponding to the Milankovitch orbital parameters.
基金financial support of the Natural Science Foundation of China (No. 41772200)China Earthquake Administration teacher research Fund (No. 20140103)+1 种基金China Geological Survey Program (No. 121201011000150021, No.DD20190351)Innovation Leading Talents Program of Qingdao (19–3–2–19–zhc)
文摘The Quaternary sediments in the Yili Basin can serve as archives for studying the Cenozoic basin-mountain relationship. In this study, based on typical natural sections and boreholes, the surficial sediments of the Huocheng area were studied, and their sedimentary ages were obtained using the optically stimulated luminescence(OSL) and electron spin resonance(ESR) dating methods. These dates, combined with changes in the sedimentary facies, provided details of the neotectonic movement in the Yili Basin and adjacent areas. By dating sediments from five sections and three boreholes, we determined that the surficial sediments of the Huocheng area were mainly formed in the Late Pleistocene, with scattered instances of Holocene sediments. The surficial sediments mainly consisted of alluvial fan facies, fluvial facies, lacustrine facies, and desert facies. Based on the activity on the Hongshanzui fault and the northern margin fault of the Wusun Mountains, the Huocheng area was uplifted synchronously with the Tianshan Mountains during the last stage of the Late Pleistocene, causing the desert facies sediments to be superimposed on the former paleo-lake sediments.
基金financially supported by the China National Nature Science Foundation(No.41072230,No.41572308,No.41977226)the State Key Laboratory of Geo-hazard Prevention&Geo-environment Protection(No.SKLGP2012Z008,No.SKLGP2016Z015)
文摘In 1999, Diexi paleo-dammed lake(2349 m a.s.l.) was discovered around Diexi town along the Minjiang River in Sichuan province. Diexi is located where the eastern edge of the Tibetan Plateau and the Sichuan Basin meet. The dammed lake was formed during the Last Glacial Maximum of the Late Pleistocene(~30,000 years ago) and began to empty about 15,000 years ago. The lacustrine sediments(up to 240 m thick) preserve abundant paleoenvironment information. In this paper, a mass of oxygen isotopes and 14 C dating from drilled cores are analyzed and discussed. The δ18 O curve on the paleo climate from this section is comparable with the coeval paleo climatic curves of ice cores and karsts in China and others. Furthermore, the physical model testing has confirmed that the disturbed zones in the core are caused by strong earthquakes occurred at least 10 times, which implies strong crustal deformation, as an important driving force, affecting climate change. This study provides a new window to observe East Asian monsoon formation, paleoenvironmental evolution and the global climate change.
基金supported by the Chinese Academy of Sciences(Grant No.XDB26000000)the National Natural Science Foundation of China(Grant No.41430102,41702001)State Key Laboratory of Palaeobiology and Stratigraphy(Nanjing Institute of Geology and Palaeontology,CAS)(Grant No.173102)。
文摘The Rhinocerotidae is one of the most common and important families in the Pleistocene mammalian fauna of South China.Since the last century,most of the Pleistocene rhinocerotid fossils were prematurely assigned to Rhinoceros sinensis,which has resulted in confusion of taxonomy for decades,especially in South China.The Yanjinggou area in Chongqing Municipality of China,where the neotype of R.sinensis came from,has yielded abundant rhinocerotid fossils and is a key area to solve this problem.A recently discovered juvenile skull from a karstic fissure in this area can be referred to Dicerorhinus sumatrensis(Fischer,1814),which is the first confirmed non-Rhinoceros rhinocerotid from the area.This new finding indicates that non-Rhinoceros fossils might have been mixed in AMNH collection from Yanjinggou and thus the diagnosis of Rhinoceros sinensis needs reformation.On the other hand,Stephanorhinus?kirchbergensis is also detected in Granger’s collection based on our reobservation.The coexistence of Rhinoceros,Dicerorhinus and Stephanorhinus shows the higher diversity of Pleistocene rhinocerotids in South China.
文摘Fifteen basaltic rock samples were collected from central Jordan at the Atarous volcanism basaltic flow area. The samples cover about 8 km2 from the Atarous Basalt flow (AB). The AB flow was introduced in the Miocene to Pleistocene periods. The samples analyze major and trace elements by using XRF. Petrography, Geochemistry and Petrogensis have investigation to carried out for the AB. The petrography analyses of the AB rocks show they are composed of plagioclase (labradorite and bytownite), pyroxene (augite), and olivine (forsterite);accessory minerals include apatite and secondary minerals magnetite, ilmenite, spinel and iddingsite. The AB is classified within alkaline to sub-alkaline and tholeiitic to Calc-Alkaline basalt. The Mg# range between 0.39 and 0.49 of basalt samples exhibits different degrees of fractionation with a low degree of melting < 15% as indicated from the varying concentration of incompatible trace elements Ba, Rb, Sr. Trace elements of primary magna show low variable abundances of compatible and incompatible elements, which reflecs a homogenous source. Geochemical parameters such as Mg# and high Ti contents indicate that the corresponding magmas are of primary origin. The tectonic setting of AB is explained by using discrimination diagrams, Ti-Zr-Sr and Nb-Zr-Y and Ti-Zr-Y, the AB plotted within the plate basalt, alkali basalt and Calk alkaline basalt field, respectively. The spider diagram shows the samples AB enrichment of the Ba, K, Nb and Ce, depletion of Nb and Y. The AB exhibited positive Nb, Ce and Ti anomalies, and negative anomalies of Ba, Sr, and P. It is attributed to the fractionation of feldspar for Ba and Sr and apatite for P depletion. The spider diagram showed a positive Nb peak, which conforms to the tertiary and to recent continental alkali basalt provinces and indicates that the AB is the product of lithosphere from upwelling asthenosphere mantle.
文摘A marine stratigraphic sequence across the Pliocene / Pleistocene boundary has been found in the north-ern continental shelf of the South China Sea. The marine Quaternary deposits in the Yinggehai Basin may ex-ceed 2,000 m in thickness, probably providing the best section for studying the lower boundary of the marinePleistocene in South China. The vertical succession with planktonic foraminifers and nannofossils revealed inboreholes in the basin has been well correlated with that in the international stratotype section of thePliocene / Pleistocene boundary at Vrica, Italy, resulting in the acquirement of a biostratigraphic boundary at1.64 Ma. This boundary, however, does not coincide with any prominent lithological palaeoenvironmentalchanges in the study area and can hardly be used in geological practice. There are, in contrast, significantchanges at the level of LAD of Globorotalia multicamerata sensu lato located below the above-mentionedboundary. The percentage of planktonic foraminifers in the total population and preservation of foraminiferaltests display great changes at this level corresponding to a clear onlap on the seismic profiles and indicating adepositional hiatus at ca. 2.0-2.5 Ma. Since the level can be widely traced in the Pearl River Mouth Basin andthe Beibu Gulf Basin and well corresponds with the marked depositional environmental changes recorded inthe west Pacific and other regions, it is recommended that the Plio / Pleistocene boundary be drawn at the levelof Gr. multicamerata sensu lato LAD, roughly concurrent with the Gauss / Matuyama turn.
文摘The environmental changes during the Late Pleistocene were more obvious in the eastern China than in other areas at the same latitude, which either between northern and southern, or between land and sea of the eastern China were mostly non-synchronous. The transitional period prior to the last glaciation came about in the northern part of the eastern China about 115,000 yr. ago. The desert environments of the inland of the north China were developed both in the glacial maximum and in the warm interglacial period, but the loess accumulation mostly took place during the glacial period. The sand dunes and the periglacial solifluctions in the lower Changjiang (Yangtze) River region were formed during the last glacial period. The event of lowest surface temperature occurred at 98,000 yr. B.P. and 59,000 yr. B.P. in the northern part of the South China Sea but not during the full-glacial stage. The phenomena mentioned . above were the result of the following reasons that the paleo-environmental changes in
文摘Tibet is the largest and highest plateau on the Earth (having 82% of the world’s land surface area falling >4km above sea level) attributed to the India and Asian convergence tectonics. Recently, high\|resolution digital topography data (Fielding et al., 1994) confirmed the earlier observations about flat erosional surfaces in the central part of the plateau (Jujin, et al., 1995) and suggested extraordinary flatness at a wide range of scales. Much of the Tibetan plateau across different accreted terranes has shallow slopes between 5°～10° and variation in relief of about 1 km, except in its marginal parts (Himalayan ranges; Kunlun mountains) where rough and high topography with intense fluvial dissections (variations in relief up to 7km) is quite frequent. However, in the southern and south\|central part of the plateau along the Pliocene\|Quaternary grabens, slopes generally steepen.
文摘A complex history of the Late Pleistocene vegetation and environmental changes for the northern part of the deciduous forest is revealed in an exceptionally well dated pollen diagram from Dongganchi in Beijing area. In 15?800- 14?700 a B.P., the arbors and aquatic plants were sparse, and the climate was cold and dry. In 14 700-13?400 a B.P., forest growth was limited, it was dominated by conifers, presumably in responded to a cooling climate. Aquatic plants became abundant. During 13?400 to 12?600 a B.P., there was a widespread development of coniferous and broad leaved mixed forest, aquatic plants decreased which corresponded to climate gradually becoming warming and dry. In 12?600-11?400 a B.P., there was alternation of coniferous and broad leaved mixed forest, so were aquatic plants. From 11?400 to 9?600 a B.P., the decreasing of trees and increasing of herbs and shrubs suggested an opening up of the vegetation in responded to cooling, probably corresponded to Younger Dryas from 10?600 to 10?300 a B.P. About 9600-7270 a B.P., the climate changed from cooler and dry to warmer and humid. About 7270-3390 a B.P., the coniferous and the broad leaved mixed forest increased, it was in responding to the “climatic optimum". About 3390-1000 a B.P., climate became cooler and dry. After 1000 a B.P., there was a severe fluctuation, indicating the temperature drop and the environmental deterioration.
文摘The Casablanca region is world famous for its fossil sites,ranging from the Mio-Pliocene to the Holocene. The"gazelles cave"at Tamaris I in the region of Casablanca(Morocco),was recently discovered during construction work.It forms a pocket,cut into the marine calcarenite of the A(i|¨)n Roumman Member and is filled with continental sediments(Lahlalfa member) of Upper Pleistocene age.The fauna is largely dominated by gazelles,hence the name given to this locality.Ankle bones discovered at the
基金granted by the national Natural Science Foundation(Grant No.41406079,41676052)the NSFC-Shandong Joint Fund for Marine Science Research Centers(No.U1606401)+2 种基金the National Key Research and Development Program of China(Grant No.2017YFC0306603)the China Ocean Mineral Resources R&D Association Project(Grant No.DY135-S1-1-02)the Foundation of Geological Survey of China(Grant No.DD20190578)。
文摘This study deals with the relationship between sea-level changes and paleoclimatic fluctuations based on the analysis of stratigraphy, grain sizes, palynology, and radiometric dating of the Yellow River delta since the Late Pleistocene. Evidence from the sedimentary record, grain sizes, and pollen provides a paleoenvironmental history of the Late Pleistocene from the boreholes of the delta. Based on a combination of grain-size analysis with lithological studies, marine deposit units contain the intervals of 13.85–16.9, 18.5–19.69, 27.9–34.8, 36.4–37.2, 48.4–51.6, and 54.1–55.9 m, and transitional facies units contain the intervals of 10.25–13.85, 16.9–18.5, 19.69–27.9, 34.8–36.4, 37.2–48.4, 51.6–54.1, and 55.9–60 m, compared with fluvial(terrestrial facies) deposit units(3.36–10.25 m). Based on pollen analysis and pollen assemblages, there were three warm-wet periods from 9.1–0.16 ka BP, 16.1–60 ka BP, and 90.1–94.6 ka BP From the top to the bottom of the borehole, the paleoclimate has an evident fluctuation: warm and moist(Holocene Optimum) —cool and dry(Younger Dryas Event)—mild semi cool—cool and dry—warm and moist. There were three warm-wet periods from 9.1–0.16 ka BP, 16.1–60 ka BP, and 90.1–94.6 ka BP, corresponding to the Holocene Optimum stage, MIS 3, and MIS 5, respectively. The warm period allowed monsoonal evergreen and broadleaved deciduous forests that corresponded to Holocene hypsithermal climatic conditions and the Late Pleistocene climatic Optimum. Three warm-wet periods occurred in marine deposit units from 9.1–0.16 ka BP, 60.1–16.1 ka BP, and 94.6–90.1 ka BP. These periods correspond to the Cangzhou transgression, Xianxian transgression, and Huanghua transgression, respectively. From 90.1–60.1 ka BP, 17.5–9.1 ka BP, and 0. 16 ka BP–1855 AD, three dry and cold phases are recognized. The phases indicate the fluvial(flood plain) sedimentary environment, corresponding to cooler and mild dry periods based on palynological results and grain-size distribution.
