Abstract:

Petrological evidence was acquired by orderly connections such as core,optical microscopy,electron probe microscopy and MAPS technology,in order to analyse the formation process of the Guanyinqiao Bed in the top of the Upper Ordovician Wufeng Formation in Sichuan Basin and its adjacent area. The results indicate that the formation process of the Guanyinqiao Bed was divided into two subprocesses and seven stages. The sedimentary subprocess went through three stages in sequence: gravity flow in shore,gravity flow in shallow sea and deep-water sandy-muddy debris flow. The four stages of the diagenetic subprocess were generally characterized by strong compaction and pressure solution,as well as the transformation of sedimentary organic matter into the porous pyrobitumen and the nonporous pyrobitumen. Based on integrating petrological features,the Guanyinqiao Bed was characterized as the deep-water sandy-muddy debris flow with complex structures formed by four subsystems: terrestrial clasts,shallow sea bioclasts,deep-water bio-clasts and organic matters. It is recommended to comprehensively apply outcrop,core,optical microscopy,electron probe microscopy and MAPS technology to systematically study the sedimentary environment and facies of the Ordovician-Silurian boundary strata in South China and even globally.

Key words: MAPS technology, petrological evidence, deep-water sandy-muddy debris flow, Wufeng Formation, Ordovician, Sichuan Basin, Guanyinqiao Bed

摘要： 通过岩心、光学显微镜、电子探针显微镜、MAPS技术等有序衔接提供的岩石学证据,约束四川盆地及邻区上奥陶统五峰组观音桥层的形成过程。结果表明,观音桥层的形成过程划分为沉积作用和埋藏成岩作用2个子过程和7个阶段。沉积作用子过程依次经历滨岸重力流、浅水重力流、深水砂泥质碎屑流等3个阶段; 埋藏成岩作用子过程的4个阶段总体表现为强烈的压实和压溶作用以及沉积有机质转化为富孔隙和无孔隙的焦沥青。融合岩石学特征,将观音桥层表征为由滨岸碎屑、浅水生屑、深水生屑、有机质等4个子系统形成的具有复杂结构的深水砂泥质碎屑流沉积。建议综合应用露头、岩心、光学显微镜、电子探针显微镜、MAPS技术等有序衔接,开展华南甚至全球奥陶系—志留系界线地层的沉积环境和沉积相研究。

关键词: MAPS技术, 岩石学证据, 深水砂泥质碎屑流, 五峰组, 奥陶系, 四川盆地, 观音桥层

CLC Number: 

• P588.2