北羌塘盆地沙土湾湖地区中晚侏罗世古生物研究及其意义

Palaeontological study of the Middle-Late Jurassic in Shatuwan Lake area of northern Qiangtang Basin and its significance

关键词:  羌塘盆地  沙土湾湖  腕足类  双壳类  侏罗系  索瓦组

Key words:  Qiangtang Basin  Shatuwan Lake area  Brachiopoda  Bivalve  Jurassic  Suowa Formation

摘要:

对北羌塘盆地沙土湾湖地区中晚侏罗世古生物的研究，为建立年代地层格架、恢复沉积环境、指导油气勘探具有重要意义。本次研究通过系统古生物化石鉴定，结合区域地质资料，确定了化石时代并探讨了化石的地层归属。结果表明：（1）原划分的白龙冰河组应归属为索瓦组；（2）地层中产出以腕足类Burmirhynchia、Holcothyris两属组合和双壳类Ceratomya cocentrica(J.Sowerby)、Ceratomya striata(J.Sowerby)、Goniomya cf.trapezicostata(Pusch)、Pholadomya cf.ginghaiensis等为代表的中侏罗世巴通期至卡洛夫早期分子；（3）索瓦组沉积时代的下限应延至中侏罗世巴通期，该组存在穿时特征；（4）化石生物群落的生活习性指示沉积于温暖正常浅海环境。这些地质记录对重建和反演北羌塘盆地沙土湾湖地区索瓦组的时空展布与岩相古地理格局提供了可靠地质依据。

Abstract:

The study of Middle to Late Jurassic paleontology is great significance for establishing chronostratigraphic framework, restoring sedimentary environment and guiding oil and gas exploration in Shatuwan Lake area of Northern Qiangtang Basin. Based on the systematic identification of fossils and regional geological data, the age of fossils is determined and the stratigraphic attribution is discussed. The results show that:(1) The original division of the Bailong-binghe Formation belongs to Suowa Formation; (2) The Burmirhynchia, Holcothyris and Ceratomya cocentrica (J. Sowerby), Ceratomya striata (J. Sowerby) and Goniomya cf. trapezicostata (Pusch)、Pholadomya cf. ginghaiensis were found in the Suowa Formation and represents Mid-Jurassic Bathonian to Early Callovian; (3) The lower limit of the Suowa Formation should be extended to Mid-Jurassic Bathonian, and the formation has the characteristics of penetrating time; (4) The living habits of the fossil indicate that they were deposited in a warm normal shallow marine environment. These geological records provide reliable geological basis for reconstruction and inversion of the time and space distribution and lithofacies paleogeographic pattern of the Suowa Formation in the Shatuwan Lake area of Northern Qiangtang Basin.