Phyllite fragments are essential for accumulating and generating talus slope at the toes of hillslopes,however,how they are linked to slope failure remains unknown.This paper reports the directional arrangement of phy...Phyllite fragments are essential for accumulating and generating talus slope at the toes of hillslopes,however,how they are linked to slope failure remains unknown.This paper reports the directional arrangement of phyllite fragments(DAPF)in phyllite talus slope at the eastern margin of the Tibetan Plateau.Field investigation,mathematical statistics and model experiments were performed in order to systematically understand the influencing factors,which include fragment shape,flat ratio,dip angle(α),and fine particle content(c).The results show that the quadrilateral fragmentgenerates a similar imbricate structure more easily than the triangular and rod fragments in the phyllite talus slope.Additionally,the flat phyllite fragments easily accumulate as imbricated structures on the phyllitetalus slope.When the dip angle(α)is in the range of 20°–30°,the minimum orientation ratio(P)is more than 50%,which means thatthe DAPF phenomenon is more obviousin the phyllite talus slope.For the fine particle content(c)at the same dip angle(α),the minimum orientation ratio(P)is 54%,and the minimum orientation ratio(P)correlates positively with the fine particle content(c).Therefore,compared with the homogeneous talusslope,the phyllite talusslopedisplays a special DAPF phenomenon.This study provides a valuable reference and presents novel knowledgefor risk assessment and engineering design against the phyllite talus slope failure mechanism.展开更多
1 Introduction Studies on lakes have become an important concern for many scientists since it is well known that lakes can monitor detailed information about ecological,hydrological and sedimentary cycles which can be
通过青藏高原中部兹格塘错湖泊沉积物总碳（TC）、总有机碳（TOC）、总氮（TN）、总硫（TS）、氢指数（HI）、氧指数（OI）和有机质的碳同位素（δ^13Corg）等多项指标的综合分析,在判断沉积物中有机质来源的基础上,根据各指标的变化特...通过青藏高原中部兹格塘错湖泊沉积物总碳（TC）、总有机碳（TOC）、总氮（TN）、总硫（TS）、氢指数（HI）、氧指数（OI）和有机质的碳同位素（δ^13Corg）等多项指标的综合分析,在判断沉积物中有机质来源的基础上,根据各指标的变化特征阐明了各自的气候指示意义,建立了兹格塘错全新世以来的古气候演化序列.10100 cal a BP兹格塘错地区进入全新世,全新世早中期为暖湿气候特征,在8600～8400和7400～7000 cal a BP发生两次强烈冷事件;中晚全新世以来气候变冷变干.这一气候演化过程与其邻近的错鄂的研究结果相近,代表了青藏高原中部全新世的气候演化特点.青藏高原中部全新世气候变化主要受太阳辐射控制.展开更多
Multi-proxies of lacustrine sediments, such as total carbon (TC), total organic carbon (TOC), total inorganic carbon (TIC), total nitrogen (TN), total sulfur (TS), hydrogen index (HI), oxygen index (OI) and stable car...Multi-proxies of lacustrine sediments, such as total carbon (TC), total organic carbon (TOC), total inorganic carbon (TIC), total nitrogen (TN), total sulfur (TS), hydrogen index (HI), oxygen index (OI) and stable carbon isotopic composition of organic matter (δ 13Corg), were analyzed using a 7.3 m core from Zigê Tangco. The source of the organic matter in the sediment was mainly from autochthonous phytoplankton, therefore the significances of proxies can be interpreted as that high TOC, TOC/TS, HI and δ13Corg values, low TC, TIC values corresponded to warm and wet climatic condition, and vice versa. The process of climatic development in the Zigê Tangco region was hence recovered. During the early and Mid-Holocene, the climate was warm and wet and intensive cold events occurred during the periods of 8600 to 8400 cal a BP and 7400 to 7000 cal a BP. In the second half of Holocene, the climate became cold and dry gradually. The palaeoclimatic process during Holocene in Zigê Tangco region matched well with that in Co Ngoin region which is ca 40 km to the south-east. Therefore this palaeoclimatic process represents the Holocene climatic feature in the Central Tibetan Plateau which has the same pattern in the Northern Tibetan Plateau, but the time and duration of some climatic events might be different. We can conclude that in Holocene solar insolation controlled the climatic pattern on the central Tibetan Plateau.展开更多
基金This study has been supported by the National Natural Science Foundation of China(Grant No.41672295)Science and Technology Project of Department of Transportation of Sichuan Province(Grant No.2015B1-1)+1 种基金Sichuan Provincial Science and Technology Plan Project(Grant No.2017JY0264)Scientific and Technological Research and Development Plan of China Railway Corporation(Grant No.P2018G047).
文摘Phyllite fragments are essential for accumulating and generating talus slope at the toes of hillslopes,however,how they are linked to slope failure remains unknown.This paper reports the directional arrangement of phyllite fragments(DAPF)in phyllite talus slope at the eastern margin of the Tibetan Plateau.Field investigation,mathematical statistics and model experiments were performed in order to systematically understand the influencing factors,which include fragment shape,flat ratio,dip angle(α),and fine particle content(c).The results show that the quadrilateral fragmentgenerates a similar imbricate structure more easily than the triangular and rod fragments in the phyllite talus slope.Additionally,the flat phyllite fragments easily accumulate as imbricated structures on the phyllitetalus slope.When the dip angle(α)is in the range of 20°–30°,the minimum orientation ratio(P)is more than 50%,which means thatthe DAPF phenomenon is more obviousin the phyllite talus slope.For the fine particle content(c)at the same dip angle(α),the minimum orientation ratio(P)is 54%,and the minimum orientation ratio(P)correlates positively with the fine particle content(c).Therefore,compared with the homogeneous talusslope,the phyllite talusslopedisplays a special DAPF phenomenon.This study provides a valuable reference and presents novel knowledgefor risk assessment and engineering design against the phyllite talus slope failure mechanism.
基金financially supported by NSFC grant 40971003DFG grants Wu 290/10-3, Wu 290/11-1
文摘1 Introduction Studies on lakes have become an important concern for many scientists since it is well known that lakes can monitor detailed information about ecological,hydrological and sedimentary cycles which can be
文摘通过青藏高原中部兹格塘错湖泊沉积物总碳（TC）、总有机碳（TOC）、总氮（TN）、总硫（TS）、氢指数（HI）、氧指数（OI）和有机质的碳同位素（δ^13Corg）等多项指标的综合分析,在判断沉积物中有机质来源的基础上,根据各指标的变化特征阐明了各自的气候指示意义,建立了兹格塘错全新世以来的古气候演化序列.10100 cal a BP兹格塘错地区进入全新世,全新世早中期为暖湿气候特征,在8600～8400和7400～7000 cal a BP发生两次强烈冷事件;中晚全新世以来气候变冷变干.这一气候演化过程与其邻近的错鄂的研究结果相近,代表了青藏高原中部全新世的气候演化特点.青藏高原中部全新世气候变化主要受太阳辐射控制.
基金National Natural Science Foundation of China (Grant Nos. 40471001 and 90411017)
文摘Multi-proxies of lacustrine sediments, such as total carbon (TC), total organic carbon (TOC), total inorganic carbon (TIC), total nitrogen (TN), total sulfur (TS), hydrogen index (HI), oxygen index (OI) and stable carbon isotopic composition of organic matter (δ 13Corg), were analyzed using a 7.3 m core from Zigê Tangco. The source of the organic matter in the sediment was mainly from autochthonous phytoplankton, therefore the significances of proxies can be interpreted as that high TOC, TOC/TS, HI and δ13Corg values, low TC, TIC values corresponded to warm and wet climatic condition, and vice versa. The process of climatic development in the Zigê Tangco region was hence recovered. During the early and Mid-Holocene, the climate was warm and wet and intensive cold events occurred during the periods of 8600 to 8400 cal a BP and 7400 to 7000 cal a BP. In the second half of Holocene, the climate became cold and dry gradually. The palaeoclimatic process during Holocene in Zigê Tangco region matched well with that in Co Ngoin region which is ca 40 km to the south-east. Therefore this palaeoclimatic process represents the Holocene climatic feature in the Central Tibetan Plateau which has the same pattern in the Northern Tibetan Plateau, but the time and duration of some climatic events might be different. We can conclude that in Holocene solar insolation controlled the climatic pattern on the central Tibetan Plateau.
