苏北废黄河三角洲是中国东部沿海研究海陆交互作用的重要区域,在该区域开展槽型钻和基坑剖面调查,同时采集泥炭层样品进行^(14)C测年,结果显示废黄河三角洲区域浅表主要分布以淤泥质黏土、黏土或砂黏互层的“千层饼”状沉积物为主的潮坪...苏北废黄河三角洲是中国东部沿海研究海陆交互作用的重要区域,在该区域开展槽型钻和基坑剖面调查,同时采集泥炭层样品进行^(14)C测年,结果显示废黄河三角洲区域浅表主要分布以淤泥质黏土、黏土或砂黏互层的“千层饼”状沉积物为主的潮坪-潟湖-砂坝相沉积层,以及以细砂、粉砂等砂质为主的废黄河沉积层,其形成时间分别为5—7 ka B.P.(中全新世早—中期)及12—19世纪黄河夺淮期间。因此认为全球性气候变化是废黄河三角洲区域沉积环境演变的主导因素,中全新世早—中期全球性的气温升高和降雨增多造成入海沉积物的增加,形成了全区广泛分布的以潮坪、潟湖、砂坝等微地貌为主的海陆交互相沉积;12—19世纪黄河夺淮期间携带大量泥沙入海,与人类改造活动共同控制了废黄河三角洲现代地貌的形成。展开更多
A total of 98 samples from two boreholes in shallow sea area and two oyster reefs in adjacent coastal plain in the northwestern coast of Bohai Bay were collected for diatom analyses and species identification.The rati...A total of 98 samples from two boreholes in shallow sea area and two oyster reefs in adjacent coastal plain in the northwestern coast of Bohai Bay were collected for diatom analyses and species identification.The ratio of the marine species Thalassionema nitzschioides to the intertidal-coastal species complex Cyclotella striata/stylorum serves as a novel proxy for assessing the strength of marine influence.Chronological data,corrected for the local residence time effect,facilitated the construction of a diatom proxy-based marine influence curve for the study area.This curve delineates the dynamics of marine influence and their correlations with paleo-climate fluctuations and the East Asian monsoon variability,as well as their role in chenier formation.Results include:(1)eight periods of intensified marine influence have been documented since 7000 a BP in the study area.The peak of each period,as determined by the diatom proxy,corresponds closely to the warm climatic phases and stronger East Asian summer monsoons,suggesting that the peaks marine influence indicate typically the periods of climatic warmth and monsoon activity intensification in the region;(2)a strong correlation exists between the development of cheniers and marine influence,and chenier formation began with the increasing marine influence and terminated at the end of warm periods as marine influence weakens.The climatic changes in the coastal area,as indicated by the diatom proxy,hold significant potential for future related research endeavors.展开更多
The southern margin of the Gurbantunggut Desert,China,is characterized by alternating layers of aeolian and alluvial deposits.Investigating the characteristics of arenaceous sediment in this area is of significant imp...The southern margin of the Gurbantunggut Desert,China,is characterized by alternating layers of aeolian and alluvial deposits.Investigating the characteristics of arenaceous sediment in this area is of significant importance for understanding the interactive processes of wind and water forces,as well as the provenance of sediment.However,there are relatively few investigations on the characteristics of such sediment at present.In this study,we researched three aeolian-alluvial interactive stratigraphic profiles and different types of surface sediment on the desert-oasis transitional zone of southern margin of the Gurbantunggut Desert.Based on the optically stimulated luminescence(OSL)dating of aeolian sand and analyses of quartz sand grain size and surface micro-texture,we explored the aeolian-alluvial environmental change at southern margin of the desert in Holocene,as well as the provenance of sediment.The results indicated that the grain size characteristics of different types of sediment in the stratigraphic profiles were similar to those of modern dune sand,interdune sand,muddy desert surface soil,and riverbed sand.Their frequency curves were unimodal or bimodal,and cumulative probability curves were two-segment or three-segment,mainly composed of suspension load and saltation load.The quartz sand in the sediment at southern margin of the desert had undergone alternating transformation of various exogenic forces,with short transportation distance and time,and sedimentary environment was relatively humid.In Holocene,southern margin of the desert primarily featured braided river deposits,and during intermittent period of river activity,there were also aeolian deposits such as sand sheet deposits,stabilized dune deposits,and mobile dune deposits.The provenance for Holocene alluvial deposits at southern margin of the desert remains relatively constant,with the debris of the Tianshan Mountains being the primary provenance.Aeolian sand is mainly near-source recharge,which is formed by in situ deposition of fluvial or lacustrine materials in southern margin of the desert transported by wind erosion,and its provenance was still the weathered debris of the Tianshan Mountains.In addition,the sand in interior of the desert may be transported by northwest wind in desert-scale,thus affecting the development of dunes in southern margin of the desert.The results of this study provide a reference for understanding the composition and provenance changes of desert sand in the context of global climate change.展开更多
笔者在琼州海峡西口第四系松散沉积物中新发现碳酸盐胶结岩,通过生物碎屑AMS14C同位素定年、全岩X衍射定量分析、扫描电镜、阴极发光、全岩主微量元素地球化学测试等方法对其进行了年代学和成因研究。结果显示,碳酸盐胶结岩的成岩时代...笔者在琼州海峡西口第四系松散沉积物中新发现碳酸盐胶结岩,通过生物碎屑AMS14C同位素定年、全岩X衍射定量分析、扫描电镜、阴极发光、全岩主微量元素地球化学测试等方法对其进行了年代学和成因研究。结果显示,碳酸盐胶结岩的成岩时代为早—中全新世,具有等厚纤柱状环边胶结、重力悬挂胶结、马牙状胶结、(似)共轴增生胶结、非等轴胶结等5种胶结物特征;阴极发光环带具有广泛发育、环带密集,可见淡水和海水相互作用的咸淡水混合带,说明其成岩环境包括淡水渗流带、咸淡水混合带、海水渗流带、海水潜流带;结合其沉积主微量元素特征,其赋存层位的沉积环境为海岸沉积环境,滨岸沉积相障壁岛亚相,属于海滩岩。综合雷州半岛西南部灯楼角珊瑚礁的海平面记录,重建了全新世琼州海峡西口地区海平面演化历史:9.9~6.7 ka BP海侵期、6.7~6.2 ka BP海退期、6.2~4.2 ka BP海侵期和4.2 ka BP至今的稳定期等四个阶段。展开更多
作为全球主要的粉尘源区之一,亚洲中部干旱区全新世环境变化备受关注,但目前仍缺乏连续的风成沉积记录。本文利用蒙古西北部Tolbo湖岩芯(TB19-A,332 cm)沉积物,在AMS 14 C定年和粒度分析基础上,采用对数正态分布函数拟合及粒级-标准偏...作为全球主要的粉尘源区之一,亚洲中部干旱区全新世环境变化备受关注,但目前仍缺乏连续的风成沉积记录。本文利用蒙古西北部Tolbo湖岩芯(TB19-A,332 cm)沉积物,在AMS 14 C定年和粒度分析基础上,采用对数正态分布函数拟合及粒级-标准偏差相结合的方法分离出沉积物中风成组分以重建区域风沙活动历史。结果显示,Tolbo湖沉积物中值粒径为15~84μm和大于84μm的组分分别是区域尘暴和局地风沙活动的良好指标。蒙古西北部地区末次冰消期晚期(13.7511.6 cal ka BP),Tolbo湖流域内有较强的局地风沙活动,可能与YD寒冷事件有关。全新世以来,流域内局地风沙活动与蒙古西北部区域尘暴活动的变化具有一致性,具体表现为:早中全新世风沙活动总体较弱,其中9.78.6 cal ka BP和76 cal ka BP为区域尘暴较强时段;5 cal ka BP之后局地风沙活动与区域尘暴强度显著增加,直至0.7 cal ka BP两者均维持在较高水平;0.3 cal ka BP以来区域尘暴活动再次增强。蒙古西北部与中国北方公海、博斯腾湖记录的尘暴历史具有一致的变化趋势,反映了与西伯利亚高压相联系的大气环流对于干旱区大范围风沙活动的影响。晚全新世风沙活动的增强可能还与冬季太阳辐射的增加有关,最近300年来强烈的区域尘暴活动除了自然因素外,可能还叠加了人类活动的影响。展开更多
通过对巢湖湖泊沉积物的总有机碳(TOC)、总氮(TN)、有机碳同位素(δ^(13)Corg)、氮同位素(δ^(15)N)和粒度参数的研究,重建了全新世以来湖泊初级生产力的变化,从而揭示了巢湖地区全新世环境变化历史。早全新世时期(10100—8200 cal a B...通过对巢湖湖泊沉积物的总有机碳(TOC)、总氮(TN)、有机碳同位素(δ^(13)Corg)、氮同位素(δ^(15)N)和粒度参数的研究,重建了全新世以来湖泊初级生产力的变化,从而揭示了巢湖地区全新世环境变化历史。早全新世时期(10100—8200 cal a BP),较高的TOC和TN、在波动中逐渐升高的δ^(13)Corg值以及高δ^(15)N值、高黏土(<4μm)含量指示了较高的湖泊初级生产力,反映气候温暖较湿;中全新世时期(8200—4200 cal a BP),TOC、TN、δ^(13)Corg值和黏土(<4μm)含量总体上较高但呈波动降低趋势,粉砂(4—64μm)含量升高,δ^(15)N值总体较低但变化幅度较大,指示初级生产力由较高水平开始逐渐降低,气候由温暖湿润逐渐向凉干方向发展;7300—5800 cal a BP和4300—3800 cal a BP的低δ^(15)N和高TN值可能受到固氮蓝藻的影响,分别对应着7500—7000 cal a BP和4200—4000 cal a BP气候事件时期夏季风强度的减弱;晚全新世前期(4200—2000 cal a BP),TOC、TN、δ^(13)Corg值、黏土(<4μm)含量的低值和较高的δ^(15)N值、高粉砂(4—64μm)含量代表初级生产力继续降低,气候环境进一步向冷干转变。全新世以来湖泊初级生产力的逐渐下降反映了季风的逐步减弱,而逐渐减少的30oN夏季太阳辐射是驱动季风减弱的主要因素。晚全新世后期(2000 cal a BP至今),各环境代用指标的变化表现出不同于全新世环境演化趋势的异常,说明湖泊环境及沉积物受人类活动的影响加剧。展开更多
通过对西天山温泉湿地钻孔沉积物Rb/Sr、Sr/Ca、Ti/Sr、Mg/Ca、Zr/Sr 5种特征元素比值综合分析与对比研究,识别温泉湿地全新世气候变化驱动模式。结果表明:(1)温泉湿地沉积物提供了新疆全新世气候变化的可靠记录,其全新世气候经历了暖干...通过对西天山温泉湿地钻孔沉积物Rb/Sr、Sr/Ca、Ti/Sr、Mg/Ca、Zr/Sr 5种特征元素比值综合分析与对比研究,识别温泉湿地全新世气候变化驱动模式。结果表明:(1)温泉湿地沉积物提供了新疆全新世气候变化的可靠记录,其全新世气候经历了暖干(10300—7700 cal a BP)-暖干向温湿过渡期(7700—7000 cal a BP)-温湿(7000—4200 cal a BP)-温干(4200—2900 cal a BP)-冷湿(2900—81 cal a BP)5个阶段变化过程。(2)与邻近区域其他替代性指标所指示的气候变化相吻合,验证了新疆地区全新世早期暖干、中晚期冷湿的气候变化模式,表明新疆地区全新世气候类似于西风模式。(3)温泉湿地沉积物化学元素比值在7700—7000 cal a BP期间指示的降温过程是8200 cal a BP全球变冷事件的响应;4200—2900 cal a BP期间指示的升温过程或许与3000—2900 cal a BP敦德冰芯反映的全新世次高温事件相关。同时,与周边区域其他替代性指标对比发现,新疆地区逐渐湿润的变化趋势可能是全新世温度降低与降水增加共同作用的结果。展开更多
文摘苏北废黄河三角洲是中国东部沿海研究海陆交互作用的重要区域,在该区域开展槽型钻和基坑剖面调查,同时采集泥炭层样品进行^(14)C测年,结果显示废黄河三角洲区域浅表主要分布以淤泥质黏土、黏土或砂黏互层的“千层饼”状沉积物为主的潮坪-潟湖-砂坝相沉积层,以及以细砂、粉砂等砂质为主的废黄河沉积层,其形成时间分别为5—7 ka B.P.(中全新世早—中期)及12—19世纪黄河夺淮期间。因此认为全球性气候变化是废黄河三角洲区域沉积环境演变的主导因素,中全新世早—中期全球性的气温升高和降雨增多造成入海沉积物的增加,形成了全区广泛分布的以潮坪、潟湖、砂坝等微地貌为主的海陆交互相沉积;12—19世纪黄河夺淮期间携带大量泥沙入海,与人类改造活动共同控制了废黄河三角洲现代地貌的形成。
基金Supported by the Youth Fund of National Natural Science Foundation of China(No.41806109)the project of China Geological Survey(Nos.DD20230091,DD20211301)。
文摘A total of 98 samples from two boreholes in shallow sea area and two oyster reefs in adjacent coastal plain in the northwestern coast of Bohai Bay were collected for diatom analyses and species identification.The ratio of the marine species Thalassionema nitzschioides to the intertidal-coastal species complex Cyclotella striata/stylorum serves as a novel proxy for assessing the strength of marine influence.Chronological data,corrected for the local residence time effect,facilitated the construction of a diatom proxy-based marine influence curve for the study area.This curve delineates the dynamics of marine influence and their correlations with paleo-climate fluctuations and the East Asian monsoon variability,as well as their role in chenier formation.Results include:(1)eight periods of intensified marine influence have been documented since 7000 a BP in the study area.The peak of each period,as determined by the diatom proxy,corresponds closely to the warm climatic phases and stronger East Asian summer monsoons,suggesting that the peaks marine influence indicate typically the periods of climatic warmth and monsoon activity intensification in the region;(2)a strong correlation exists between the development of cheniers and marine influence,and chenier formation began with the increasing marine influence and terminated at the end of warm periods as marine influence weakens.The climatic changes in the coastal area,as indicated by the diatom proxy,hold significant potential for future related research endeavors.
基金the National Natural Science Foundation of China(42071011)the 2023 Annual Postgraduate Research and Innovation Foundation of Fujian Normal University,China.
文摘The southern margin of the Gurbantunggut Desert,China,is characterized by alternating layers of aeolian and alluvial deposits.Investigating the characteristics of arenaceous sediment in this area is of significant importance for understanding the interactive processes of wind and water forces,as well as the provenance of sediment.However,there are relatively few investigations on the characteristics of such sediment at present.In this study,we researched three aeolian-alluvial interactive stratigraphic profiles and different types of surface sediment on the desert-oasis transitional zone of southern margin of the Gurbantunggut Desert.Based on the optically stimulated luminescence(OSL)dating of aeolian sand and analyses of quartz sand grain size and surface micro-texture,we explored the aeolian-alluvial environmental change at southern margin of the desert in Holocene,as well as the provenance of sediment.The results indicated that the grain size characteristics of different types of sediment in the stratigraphic profiles were similar to those of modern dune sand,interdune sand,muddy desert surface soil,and riverbed sand.Their frequency curves were unimodal or bimodal,and cumulative probability curves were two-segment or three-segment,mainly composed of suspension load and saltation load.The quartz sand in the sediment at southern margin of the desert had undergone alternating transformation of various exogenic forces,with short transportation distance and time,and sedimentary environment was relatively humid.In Holocene,southern margin of the desert primarily featured braided river deposits,and during intermittent period of river activity,there were also aeolian deposits such as sand sheet deposits,stabilized dune deposits,and mobile dune deposits.The provenance for Holocene alluvial deposits at southern margin of the desert remains relatively constant,with the debris of the Tianshan Mountains being the primary provenance.Aeolian sand is mainly near-source recharge,which is formed by in situ deposition of fluvial or lacustrine materials in southern margin of the desert transported by wind erosion,and its provenance was still the weathered debris of the Tianshan Mountains.In addition,the sand in interior of the desert may be transported by northwest wind in desert-scale,thus affecting the development of dunes in southern margin of the desert.The results of this study provide a reference for understanding the composition and provenance changes of desert sand in the context of global climate change.
文摘笔者在琼州海峡西口第四系松散沉积物中新发现碳酸盐胶结岩,通过生物碎屑AMS14C同位素定年、全岩X衍射定量分析、扫描电镜、阴极发光、全岩主微量元素地球化学测试等方法对其进行了年代学和成因研究。结果显示,碳酸盐胶结岩的成岩时代为早—中全新世,具有等厚纤柱状环边胶结、重力悬挂胶结、马牙状胶结、(似)共轴增生胶结、非等轴胶结等5种胶结物特征;阴极发光环带具有广泛发育、环带密集,可见淡水和海水相互作用的咸淡水混合带,说明其成岩环境包括淡水渗流带、咸淡水混合带、海水渗流带、海水潜流带;结合其沉积主微量元素特征,其赋存层位的沉积环境为海岸沉积环境,滨岸沉积相障壁岛亚相,属于海滩岩。综合雷州半岛西南部灯楼角珊瑚礁的海平面记录,重建了全新世琼州海峡西口地区海平面演化历史:9.9~6.7 ka BP海侵期、6.7~6.2 ka BP海退期、6.2~4.2 ka BP海侵期和4.2 ka BP至今的稳定期等四个阶段。
文摘作为全球主要的粉尘源区之一,亚洲中部干旱区全新世环境变化备受关注,但目前仍缺乏连续的风成沉积记录。本文利用蒙古西北部Tolbo湖岩芯(TB19-A,332 cm)沉积物,在AMS 14 C定年和粒度分析基础上,采用对数正态分布函数拟合及粒级-标准偏差相结合的方法分离出沉积物中风成组分以重建区域风沙活动历史。结果显示,Tolbo湖沉积物中值粒径为15~84μm和大于84μm的组分分别是区域尘暴和局地风沙活动的良好指标。蒙古西北部地区末次冰消期晚期(13.7511.6 cal ka BP),Tolbo湖流域内有较强的局地风沙活动,可能与YD寒冷事件有关。全新世以来,流域内局地风沙活动与蒙古西北部区域尘暴活动的变化具有一致性,具体表现为:早中全新世风沙活动总体较弱,其中9.78.6 cal ka BP和76 cal ka BP为区域尘暴较强时段;5 cal ka BP之后局地风沙活动与区域尘暴强度显著增加,直至0.7 cal ka BP两者均维持在较高水平;0.3 cal ka BP以来区域尘暴活动再次增强。蒙古西北部与中国北方公海、博斯腾湖记录的尘暴历史具有一致的变化趋势,反映了与西伯利亚高压相联系的大气环流对于干旱区大范围风沙活动的影响。晚全新世风沙活动的增强可能还与冬季太阳辐射的增加有关,最近300年来强烈的区域尘暴活动除了自然因素外,可能还叠加了人类活动的影响。
文摘通过对巢湖湖泊沉积物的总有机碳(TOC)、总氮(TN)、有机碳同位素(δ^(13)Corg)、氮同位素(δ^(15)N)和粒度参数的研究,重建了全新世以来湖泊初级生产力的变化,从而揭示了巢湖地区全新世环境变化历史。早全新世时期(10100—8200 cal a BP),较高的TOC和TN、在波动中逐渐升高的δ^(13)Corg值以及高δ^(15)N值、高黏土(<4μm)含量指示了较高的湖泊初级生产力,反映气候温暖较湿;中全新世时期(8200—4200 cal a BP),TOC、TN、δ^(13)Corg值和黏土(<4μm)含量总体上较高但呈波动降低趋势,粉砂(4—64μm)含量升高,δ^(15)N值总体较低但变化幅度较大,指示初级生产力由较高水平开始逐渐降低,气候由温暖湿润逐渐向凉干方向发展;7300—5800 cal a BP和4300—3800 cal a BP的低δ^(15)N和高TN值可能受到固氮蓝藻的影响,分别对应着7500—7000 cal a BP和4200—4000 cal a BP气候事件时期夏季风强度的减弱;晚全新世前期(4200—2000 cal a BP),TOC、TN、δ^(13)Corg值、黏土(<4μm)含量的低值和较高的δ^(15)N值、高粉砂(4—64μm)含量代表初级生产力继续降低,气候环境进一步向冷干转变。全新世以来湖泊初级生产力的逐渐下降反映了季风的逐步减弱,而逐渐减少的30oN夏季太阳辐射是驱动季风减弱的主要因素。晚全新世后期(2000 cal a BP至今),各环境代用指标的变化表现出不同于全新世环境演化趋势的异常,说明湖泊环境及沉积物受人类活动的影响加剧。
文摘通过对西天山温泉湿地钻孔沉积物Rb/Sr、Sr/Ca、Ti/Sr、Mg/Ca、Zr/Sr 5种特征元素比值综合分析与对比研究,识别温泉湿地全新世气候变化驱动模式。结果表明:(1)温泉湿地沉积物提供了新疆全新世气候变化的可靠记录,其全新世气候经历了暖干(10300—7700 cal a BP)-暖干向温湿过渡期(7700—7000 cal a BP)-温湿(7000—4200 cal a BP)-温干(4200—2900 cal a BP)-冷湿(2900—81 cal a BP)5个阶段变化过程。(2)与邻近区域其他替代性指标所指示的气候变化相吻合,验证了新疆地区全新世早期暖干、中晚期冷湿的气候变化模式,表明新疆地区全新世气候类似于西风模式。(3)温泉湿地沉积物化学元素比值在7700—7000 cal a BP期间指示的降温过程是8200 cal a BP全球变冷事件的响应;4200—2900 cal a BP期间指示的升温过程或许与3000—2900 cal a BP敦德冰芯反映的全新世次高温事件相关。同时,与周边区域其他替代性指标对比发现,新疆地区逐渐湿润的变化趋势可能是全新世温度降低与降水增加共同作用的结果。
