滇东北会泽灯影组硅质岩成因及沉积环境——来自岩石学和地球化学证据

通过1：50 000区域地质调查，发现云南省会泽县一带灯影组中普遍发育硅质岩。本文通过硅质岩岩石学特征和地球化学特征分析，重点探讨了灯影组各段硅质岩的成因机制和沉积环境。结果表明：震旦系-寒武系灯影组下段硅质岩中相对富集Al和Ti，总稀土（ΣREE）相对较高，Ce呈负异常，Eu呈正异常；中段硅质岩中相对富集Ca和Mg，总稀土较低，LREE>HREE，Ce呈负异常，Eu呈正异常；上段硅质岩总稀土较低，LREE>HREE，Ce大部分呈负异常，Eu呈正负异常。综合硅质岩岩石学、地球化学特征，并结合震旦纪区域地质构造演化，认为研究区内下段硅质岩表现为正常海水沉积、中段硅质岩表现为典型热水沉积、上段表现出正常海水沉积受热水沉积影响的特征。硅质岩形成于复杂大陆边缘的浅海陆棚环境。

Petrogenesis and Sedimentary Environment of Cherts of Dengying Formation in Huize County,Northeastern Yunnan: Evidence from Petrology and Geochemistry

The cherts of Dengying Formation are widely distributed in Huize County in northeastern Yunnan in the 1:50 000 regional survey. This paper mainly focuses on the petrogenesis and their petrological and geochemical characteristics. The cherts in the lower segment of the Sinian-Cambrian Dengying Formation are relatively rich in Al, Ti and ΣREE, with negative Ce anomaly and positive Eu anomaly; the cherts in the middle segment are characterized by high contents of Ca and Mg, relatively low contents of ΣREE (total LREE> total HREE), with negative Ce anomaly and various Eu anomalies; the cherts in the upper segment display relatively low contents of ΣREE (total LREE> total HREE), with negative Ce anomaly and various Eu anomalies. Combined with the regional tectonic evolution in the Sinian-Cambrian region, the petrological and geochemical characteristics indicate that the lower segment chert is deposited in a normal seawater environment, the middle segment chert is a product of a hydrothermal sedimentary environment, and the upper segment chert belongs to a product of normal seawater influenced obviously by hydrothermal fluids. The Dengying Formation chert in the Huize area is formed in a shallow sea shelf environment on the edge of heterogeneous continent.