福建大田县北部船山组地层沉积特征及沉积环境分析

Sedimentary characteristics and sedimentary environment analysis of the Chuanshan Formation in the northern part of Datian County,Fujian

福建大田县北部船山组位于南武夷晚古生代拗陷区大田—龙岩拗陷带北侧边部,近年来发现厚度较大的灰岩矿。根据地层、岩性、岩相资料分析,认为大田北部船山组按照沉积旋回自下而上可划分为三个岩性段,并划分出白云质灰岩相、微晶灰岩相、(含)生物碎屑微晶灰岩相、扁豆状砾屑灰岩相、豹纹状灰岩相、角砾状灰岩相、海百合生物碎屑泥晶灰岩相等7种岩相类型,在此基础上,将船山组沉积环境划分为局限台地、开阔台地、台地边缘浅滩、开阔海陆棚和台地边缘斜坡等5种类型,其中开阔台地是主要沉积环境,属于典型的浅水碳酸盐岩台地相。指出区内船山组厚度较大主要受沉积期时水体较浅和地壳下降幅度同沉积物堆积速度基本相同的两个因素所致。

The Chuanshan Formation in the northern part of Datian County,Fujian is located at the northern edge of the Datian-Longyan depression zone in the Late Paleozoic depression area of South Wuyi area.In recent years,thick limestone deposits have been discovered.According to the analysis of stratigraphic,lithology and lithoface data,it is considered that the Chuanshan Formation in the northern part of Datian County can be divided into three lithological sections from bottom to top according to the sedimentary cycle.There are seven types of lithofacies including dolomitic limestone face,microcrystalline limestone face,bioclastic microcrystalline limestone face,lentilar-like gravel limestone face,leopard-like limestone face,breccia-like limestone face,and crinoids bioclastic micrite face.The sedimentary environment of the Chuanshan Formation is divided into five types,confined platform,open platform,platform margin shoal,open sea shelf and platform margin slope.Among them,the open platform is the main sedimentary environment and belongs to the typical shallow-water carbonate platform face.It is pointed out that the larger thickness of the Chuanshan Formation in the area is mainly caused by two factors,the shallow water body during the sedimentary period and the fact that the magnitude of the crustal decline is basically the same as the sediment accumulation rate.