桂林晚白垩世红色岩溶建造中溶积钙质泥岩的成因及地质意义初探

GENESIS AND GEOLOGICAL SIGNIFICANCE OF THE SOLUTION-DEPOSITED CALCAREOUS MUDSTONE OF LATE CRETACEOUS RED KARST FORMATION IN GUILIN

本文从土壤学的角度,探讨桂林晚白垩世红色岩溶建造中溶积钙质泥岩的成因及其所反映的岩溶环境和岩溶发育特征。通过溶积钙质泥岩与石灰土两者特征的比较,论证前者为古溶蚀残余成土作用的产物,经沉积-堆积再固结而成。并通过两者形成条件及演化过程的分析,推论桂林在晚白垩世时期主要为炎热多雨的气候环境,岩溶发育,地貌组合形态以峰丛洼地为主。

The red karst formation formed in Late Cretaceous is scattered in Guilin karst area. There are different point of views about the karst environment reflected by the red karst formation. The authors have studied the red karst formation on lithology and palaeontology, and considered that it is the deposits occurred in negative karst forms under a humid-hot climate environment. This paper, however, goes further into the genesis and forming environment of the solution-deposited calcareous mudstone(SDCM)in terms of the pedology prin-ceples. Through comparing the SDCM with the limestone soils in their occurrence and composition, we consider that the SDCM is formed by deposition-accumulation and solidification of the products during palaeosolution - residue earth- forming process. Tn addition, based on the analysis of forming condition and evolution of SDCM and limestone soils, we also found that the characteristics of both reflected a climate environment of humid- hot during Late Cretaceous in Guilin area. During that time, karst was well - developed, and peak-cluster depression was the major landform. The red karst formation formed in Late Cretaceous often can be seen in South China. Hence, to study the genesis of SDCM of red karst formation has important significance for reconstruction of palaokarst environment.