Pore-infillings Characteristics of Siliceous Rocks in Nadanhada Terrane

Abstract

In order to reveal the mineral filling sequence and fluid action process in the dissolution pores of the bedded siliceous rocks in the Dongrong Formation of the Sanjiang Basin, the petrological characteristics, geochemical analysis and testing methods were comprehensively applied to research, and the databases of major amount and rare earth elements of siliceous rocks were established, and the sedimentary environment, origin and source of siliceous materials were systematically judged again. The results show that the siliceous rocks of the Nadanhada terrane exposed in the Sanjiang Basin are biogenic. On the basis of early metasomatic microbial dolomite, the layered siliceous rocks have experienced six stages (three fluid properties) of fluid filling, including magnesium rich hydrothermal fluid, siliceous hydrothermal fluid, asphalt and siliceous hydrothermal fluid. Siliceous rock cavity filling material is the product of fluid rock coupling under different temperatures, concentrations and reaction systems under the control of different tectonic movements and hydrocarbon maturation.