东海陆架南部海域及周边陆域白垩纪海侵标志及地质意义

CRETACEOUS TRANSGRESSION IN THE SOUTHERN EAST CHINA SEA SHELF BASIN AND ADJACENT LAND AREAS:EVIDENCE AND GEOLOGICAL SIGNIFICANCE

东海陆架盆地南部在新生界有诸多油气发现,其下很可能发育了巨厚的、规模巨大的中生界,但对古地理背景的认识尚不清楚,制约了对其进一步开展工作。利用少量钻井及前人关于周边陆域白垩系的零星资料,从多因素入手,综合分析了白垩纪岩相古地理背景,结果表明,在东海陆架盆地南部及周边陆域广泛发育了岩石、化石、生物标志物等各类海侵标识,且其特征和分布具有区域规律性:从花东海盆的放射虫—台湾的菊石、瓣腮类—东海陆架盆地的海绿石—沿海石浦地区的灰岩—浙东付鲚鱼—武夷山及邻区的红藻、褐藻及线叶植物,对应指示的沉积环境自SE至NW依次为深海、浅海、海陆过渡、陆地的总趋势,推测古海侵方向为自SE往NW向。而海侵事件控制了早白垩世东海南部周边邻域的岩相古地理背景,也塑造了如茶湾组这样的有利烃源岩层。

There seems sin under the Cenozoic, a thick and in which Mesozoic palaeogeographic pattern wide Mesozoic in the southern part of the East China Sea Shelf Ba- a large reserve of gas and oil has been discovered. However, the of the area remains unclear, that restrict the further exploration of the basin. In this paper, we made an integrated analysis of lithofacies and palaeogeography for the Cretaceous with a few drilling data and incomplete outcrops upon the basis of single factor facies anal- ysis. It is revealed that the distribution of depositional characteristics, such as the paleontological, mineralogical and geochemical indicators, is all in a transgressive pattern from Radiolarian （Huatung basin）-Ammonite and Lamellibranchia （Taiwan）-Glauconite （the East China Sea Shelf Basin）-Shipu Limestone （Xiangshan, Zhejiang）-Marine fish （Zhejiang）-Phaeophyta, Rhodophyta and Plants （Wuy- ishan, Fujian） from SE to NW. The depositional environment changes in a general trend from abys- mal environment to shallow sea, transitional zone, and to land. This trend probably indicates that the direction of transgression in the early Cretaceous was from SE to NW, which controlled the lithofacies and palaeogeographic pattern of the early Cretaceous in the southern part of the East China Sea Shelf Basin and adjacent land areas. High quality source rocks, such as those in the Chawan Formation, were formed in the transgression.