东海陆架的古河道和古三角洲
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摘要
基于 1996年中法东海海洋地质调查电火花单道地震资料 ,确定了晚更新世早期和中期长江 (黄河 )水下三角洲的分布范围和大致时间。中更新世晚期东海陆架为一自西南向东北倾斜的广阔的河流冲积平原 ,晚更新世以来自西北方向的大型河流的三角洲受此控制主要发育在东北部较低地区。东海陆架较大古河道多发育在末次冰期中的亚间冰期 (氧同位素 3期 )。
Based on seismic records using SIG sparker from a joint Sino French study on marine geology of the East China Sea in 1996,the distribution area of submarine paleodeltas of the Yangtze River(and/or the Yellow River)during the early and middle time of the late Pleistocene is determined. (1)In the early time of the late Pleistocene,about 80～70 ka BP,the Yangtze River(and /or the Yellow River)submarine deltas widely spread in the northeast of the middle outer ECS shelf where the deltas lay at water depth of 40～90 m and had a thickness of about 10～35 m.In the middle time of the late Pleistocene,about 50～43 ka BP,the deltas settled in the middle of the outer ECS shelf and went down 70～ 120 m from the sea surface.They advanced all the time from northwest to southeast as the sea level dropped. (2)The fluvial affection was less during the early and late time of the last glaciation(the oxygen isotopic stage 4 and stage 2)than it was during the sub interglacial of the last glaciation,especially around 40 ka BP when many big paleochannels formed. (3)The alluvial plain U7 on the ECS shelf sloped gradually from southwest to northeast in the upper of the middle Pleistocene(oxygen isotopic stage 6).It is certain that high ground was affected a little by transgression.Meanwhile,it made that in late Pleistocene,deltas mainly appeared in the low ground in the northeastern part.
Based on seismic records using SIG sparker from a joint Sino French study on marine geology of the East China Sea in 1996,the distribution area of submarine paleodeltas of the Yangtze River(and/or the Yellow River)during the early and middle time of the late Pleistocene is determined. (1)In the early time of the late Pleistocene,about 80～70 ka BP,the Yangtze River(and /or the Yellow River)submarine deltas widely spread in the northeast of the middle outer ECS shelf where the deltas lay at water depth of 40～90 m and had a thickness of about 10～35 m.In the middle time of the late Pleistocene,about 50～43 ka BP,the deltas settled in the middle of the outer ECS shelf and went down 70～ 120 m from the sea surface.They advanced all the time from northwest to southeast as the sea level dropped. (2)The fluvial affection was less during the early and late time of the last glaciation(the oxygen isotopic stage 4 and stage 2)than it was during the sub interglacial of the last glaciation,especially around 40 ka BP when many big paleochannels formed. (3)The alluvial plain U7 on the ECS shelf sloped gradually from southwest to northeast in the upper of the middle Pleistocene(oxygen isotopic stage 6).It is certain that high ground was affected a little by transgression.Meanwhile,it made that in late Pleistocene,deltas mainly appeared in the low ground in the northeastern part.
引文
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2 金翔龙主编 .东海海洋地质 .北京 :海洋出版社 ,1992 .5 2 4
3 石斯器 ,杨长恕 .东海外陆架浅层地震地层学的初步研究 .见 :杨子赓 ,林和茂主编 .中国近海及沿海地区第四纪进程与事件 ,北京 :地质出版社 ,1989.62～ 67
4 袁迎如 .东海大陆架外部的晚更新世晚期长江河口 .海洋学报 ,1992 ,14 ( 6) :5 2～ 60
5 刘振夏 ,Berne S.中更新世以来东海陆架的古环境 .海洋地质与第四纪地质 ,1999,19( 2 ) :1～ 10
6 唐保根 .东海陆架第四纪地层 .见 :杨子赓 ,林和茂主编 .中国第四纪地层与国际对比 ,北京 :地质出版社 ,1996.5 6～ 75
7 Berne S( ed) . Donghai Cruise preliminary report. IF REMERcruise report DRO/ GN/ 96/ 2 9,1996,74
8 Chappell J,Omura A,Esat T,Mc Culloch M,Pandolfi J,Ota Y,Pillans B.Reconciliation of late Quaternary sea levels derivedfrom coral terraces at Huon Peninsula with deep sea oxygen iso-tope records.Earth and Plainetary Science Letters,1996,14 1:2 2 7～ 2 3 6
9 Martinson D G,et al..Age dating and the orbital theory of theice age:development of a high resolution 0 to 3 0 0 0 0 0 yearschronostratigraphy.Quaternary Research,1987,2 7:1～ 2 9
10 黄庆福 ,苟淑名 ,孙维敏等 ,东海 DC-2孔柱状岩心的地层划分 .海洋地质与第四纪地质 ,1984,4( 1) :11～ 2 6
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