泌阳凹陷核桃园组湖相碳酸盐岩系藻类组合及古环境  

Alga Assembtages and Palaeoenvironment of Eogene Hetaoyuan Formation Lacustrine Carbonate Rocks in Biyang Depression, Henan Province

作　　者：闫存凤[1] 黄杏珍[1] 王随继[1] 

机构地区：[1]中国科学院兰州地质研究所,北京大学

出　　处：《沉积学报》1996年第A00期57-62,共6页Acta Sedimentologica Sinica

基　　金：国家自然科学基金

摘　　要：本文研究了我国泌阳凹陷下第三系核桃园组核三上段──核二段湖相碳酸盐岩系中的藻类化石，划分出三个藻类组合，Ｆｒｏｍｅａｃｈｙｔｒａ组合，Ｄｉｃｔｙｏｔｉｄｉｕｍ组合和Ｒｕｇａｓｐｈａｅｒａ－Ｄｉｃｔｙｏｔｉｄｉｕｍ－Ｃｏｎｃｅｎｔｒｉｃｙｓｔｅｓ组合，它们反映的盐度变化依次由高到低。藻类的纵向分布呈现出繁盛—衰亡—繁盛的旋回变化，在藻类繁盛期指示高盐度的藻类组合与指示低盐度藻类组合交替出现。藻类组合特征及旋回变化表明：泌阳凹陷核桃园组核三上段—核二段沉积时期，古湖泊水体的盐度在微咸水环境的背景下，存在三次咸化期和两次淡化期的波动，古气候经历了三次相对炎热于旱期和两次温暖湿润期的演变。微量元素含量变化也反映了这一特征。Biyang Depression is a Mesozoic-Cenozoic interior oil-bearing basin, with an area of 1000 km2, in eastern China. The lacustrine carbonate rocks of the Eogene Hetaoyuan Formation deposited in the center of this basin. They are mainly composed of mudstone, dolomitic mudstone, argillic dolostone, dolostone, silty dolostone and intercalated with alkali beds. The alga fossils from the lacustrine carbonate rocks in the upper third to the second member of Hetaoyuan Formation were studied. They could be dentified as three assemblages, Fromea chytra assemblage, Dictyotidium assemblage and Rugasphaera-Dictyotidium-Concentricystes It reflected that the palaeo-lake water salinity changed from the higher to lower successively. In addition, the vertical alga distribution assumed a cyclical change of flourishing and declining. The higher silinity alga assemlage and the lower one alternately appeared in the algae flourishing periods. It was showed that the palaeo-lake water salinity might undergo three relatively Salty water stages and two relatively fresh water stages under the brackish water setting and the palaeclimate period might include two relatively warm and wet stages and three relatively hot and dry stages in the depositional period of the upper third to the second member of Hetaoyuan Formation.

关 键 词：碳酸盐岩 藻类组合 古环境 泌阳凹陷 

分 类 号：P588.245[天文地球—岩石学] P531[天文地球—地质学]