A new approach to the basic composition char- acter of deep sea sediment is discussed in this paper for indi- cating its paleoenvironment meaning. For this purpose high precision grain size character of sediments from...A new approach to the basic composition char- acter of deep sea sediment is discussed in this paper for indi- cating its paleoenvironment meaning. For this purpose high precision grain size character of sediments from core NS93-5 was analysed by using the Laser Diffraction Particle Size Analyzer, combining with results of micropalaeontologic counting and trace element and calcium carbonate testing, to illustrate some main grain size indexes and their relationship with micropalaeontologic makeup and terrigenous input. It was showed that the grain sizes of deep sea sediment may reflect materials properties and their buildup framework. There are obvious relations between indexes of grain size ranges and abundances of different micropalaeontologic groups and terrigenous matters, in which grain size of <2 μm represents terrigenous composition, that of >5 μm is mainly made up of various microfossil shells, except for containing volcanic dust layers, and median diameter (MD) of grain size may be taken as proxy of paleoproductivity or paleoecologi- cal dynamic. These index and proxy were consistent with micropaleontologic records for well indicating important features of paleoceanographic ecology, showing that the mi- cropalaeontologic growth in the southwestern slope area of the South China Sea (SCS) was negatively correlated to ter- rigenous input since late Pleistocene and corresponded to glacial-interglacial global climatic changes incompletely, but had a regional particularity in this sea area.展开更多
The Mudui stratigraphic section represents the typical records of sedimentation processes of sand dunes and interdune depressions on the east coast of Hainan Island.Based on high-density sampling and optically stimula...The Mudui stratigraphic section represents the typical records of sedimentation processes of sand dunes and interdune depressions on the east coast of Hainan Island.Based on high-density sampling and optically stimulated luminescence(OSL) dating of the strata of the section,the grain-size composition,grain-size parameters,cumulative distribution probability curve,and grain-size-sensitivity indexes(SC/D) were analyzed.The analyzed results show that the grain-size features of aeolian sand,weakly developed sandy paleosol,two-facies(aeolian and aqueous) deposits,and lagoon deposits are all different.This indicates four evolutionary phases of the sedimentary environment of the east coast of Hainan Island since 38 ka B.P.Phase I:38-22 ka B.P.;phase II:22-17 ka B.P.;phase III:17-10 ka B.P.;phase IV:10 ka B.P.-present.The climate experienced the hot-wet/hot-dry,hot-wet/hot-dry,and warm-wet/hot-wet fluctuations,and the sedimentary environment also underwent lagoon deposition,dune and interdune depression deposition,dune stabilization and soil development,shifting sand deposition,and evolutionary processes.展开更多
对杭州湾北岸3处现代潮滩沉积物进行高精度粒度分析,查找研究区潮滩不同微相的粒度特征和差异,提取基于粒度分析的潮滩微相识别敏感指标,并将其应用到该区域的全新世钻孔潮滩沉积物中,识别钻孔潮滩沉积微相,据此建立研究区全新世早期的...对杭州湾北岸3处现代潮滩沉积物进行高精度粒度分析,查找研究区潮滩不同微相的粒度特征和差异,提取基于粒度分析的潮滩微相识别敏感指标,并将其应用到该区域的全新世钻孔潮滩沉积物中,识别钻孔潮滩沉积微相,据此建立研究区全新世早期的海平面曲线。研究表明:杭州湾北岸现代高潮滩盐沼沉积物粘土含量明显高于高潮滩下部和中潮滩,而砂含量与之相反;高潮滩盐沼平均粒径等粒度参数明显小于中、高潮滩的粒度参数;盐沼沉积物粒度频率曲线峰态宽缓,明显区别于高潮滩下部和中潮滩。上述现代潮滩微相粒度敏感指标可成功应用到钻孔潮滩沉积微相划分中,并建立了该区域全新世早期海平面曲线。曲线显示,9700~8700 cal a BP期间海平面上升约11.6 m,海平面上升速率可达1.2 cm/a。现代潮滩不同位置沉积物粒度参数的规律性差异可作为潮滩微相识别的有效指标,为古潮滩沉积微相识别和古海平面重建提供参考依据。展开更多
基金This work was supported by the Knowledge In-novation Project of the Chinese Academy of Sciences(Grant No.KZCX3-SW-220)the National Natural Science Foundation of China(Grant No.40476024)+1 种基金the National Key Project for Basic Research of China(Grant No.2000078500)the Ministry of Science and Tech-nology of China(Grant No.2003DEA6N041).
文摘A new approach to the basic composition char- acter of deep sea sediment is discussed in this paper for indi- cating its paleoenvironment meaning. For this purpose high precision grain size character of sediments from core NS93-5 was analysed by using the Laser Diffraction Particle Size Analyzer, combining with results of micropalaeontologic counting and trace element and calcium carbonate testing, to illustrate some main grain size indexes and their relationship with micropalaeontologic makeup and terrigenous input. It was showed that the grain sizes of deep sea sediment may reflect materials properties and their buildup framework. There are obvious relations between indexes of grain size ranges and abundances of different micropalaeontologic groups and terrigenous matters, in which grain size of <2 μm represents terrigenous composition, that of >5 μm is mainly made up of various microfossil shells, except for containing volcanic dust layers, and median diameter (MD) of grain size may be taken as proxy of paleoproductivity or paleoecologi- cal dynamic. These index and proxy were consistent with micropaleontologic records for well indicating important features of paleoceanographic ecology, showing that the mi- cropalaeontologic growth in the southwestern slope area of the South China Sea (SCS) was negatively correlated to ter- rigenous input since late Pleistocene and corresponded to glacial-interglacial global climatic changes incompletely, but had a regional particularity in this sea area.
文摘The Mudui stratigraphic section represents the typical records of sedimentation processes of sand dunes and interdune depressions on the east coast of Hainan Island.Based on high-density sampling and optically stimulated luminescence(OSL) dating of the strata of the section,the grain-size composition,grain-size parameters,cumulative distribution probability curve,and grain-size-sensitivity indexes(SC/D) were analyzed.The analyzed results show that the grain-size features of aeolian sand,weakly developed sandy paleosol,two-facies(aeolian and aqueous) deposits,and lagoon deposits are all different.This indicates four evolutionary phases of the sedimentary environment of the east coast of Hainan Island since 38 ka B.P.Phase I:38-22 ka B.P.;phase II:22-17 ka B.P.;phase III:17-10 ka B.P.;phase IV:10 ka B.P.-present.The climate experienced the hot-wet/hot-dry,hot-wet/hot-dry,and warm-wet/hot-wet fluctuations,and the sedimentary environment also underwent lagoon deposition,dune and interdune depression deposition,dune stabilization and soil development,shifting sand deposition,and evolutionary processes.
基金国家自然科学基金项目《杭州湾北岸全新世早期(10-9 cal ka BP)高精度海平面重建及沉积环境响应》(批准号:41706098)《基于微体化石识别全新世高海面阶段长江口外水团相互作用及调控机制》(批准号:42076081)。
文摘对杭州湾北岸3处现代潮滩沉积物进行高精度粒度分析,查找研究区潮滩不同微相的粒度特征和差异,提取基于粒度分析的潮滩微相识别敏感指标,并将其应用到该区域的全新世钻孔潮滩沉积物中,识别钻孔潮滩沉积微相,据此建立研究区全新世早期的海平面曲线。研究表明:杭州湾北岸现代高潮滩盐沼沉积物粘土含量明显高于高潮滩下部和中潮滩,而砂含量与之相反;高潮滩盐沼平均粒径等粒度参数明显小于中、高潮滩的粒度参数;盐沼沉积物粒度频率曲线峰态宽缓,明显区别于高潮滩下部和中潮滩。上述现代潮滩微相粒度敏感指标可成功应用到钻孔潮滩沉积微相划分中,并建立了该区域全新世早期海平面曲线。曲线显示,9700~8700 cal a BP期间海平面上升约11.6 m,海平面上升速率可达1.2 cm/a。现代潮滩不同位置沉积物粒度参数的规律性差异可作为潮滩微相识别的有效指标,为古潮滩沉积微相识别和古海平面重建提供参考依据。
