雪玉洞母岩沉积地质特征及其对次生沉积物的影响

发布时间：2018-12-10 08:14

【摘要】：为了研究洞穴母岩对洞穴系统及次生沉积物产生的影响,以重庆丰都雪玉洞母岩为研究对象,对其沉积地质特征进行了详细的研究,同时还探讨母岩的沉积地质特征与洞穴发育及次生沉积物特征之间的关联。结果表明,雪玉洞的母岩层位为下三叠统飞仙关组第二段,其沉积相为颗粒滩。母岩的岩性为砂屑灰岩、鲕粒灰岩、砾屑灰岩,夹少量微晶灰岩。母岩和洞穴次生沉积物的主要矿物成分是低镁方解石(LMC,low magnesium calcite)。母岩较低的Mg/Ca导致洞穴滴水的Mg/Ca也较低,这使得组成次生沉积物的低镁方解石晶体快速侧向生长,并导致方解石晶体纯净、粗大且自形程度高。雪玉洞母岩顶底板岩层沉积期稳定的滩间海沉积环境有助于形成高强度的厚层微晶灰岩从而为洞穴系统的发育提供有效的支撑。这表明洞穴母岩的沉积地质特征会在物质基础的层面对洞穴系统的发育以及洞穴次生沉积物的特征产生显著影响。
[Abstract]:In order to study the effect of cave parent rock on cave system and secondary sediments, the sedimentary geological characteristics of Xueyudong parent rock in Fengdu, Chongqing, were studied in detail. The relationship between sedimentary geological characteristics of parent rock and cave development and secondary sediment characteristics is also discussed. The results show that the parent rock of Xueyudong is the second member of the Feixianguan formation of the Lower Triassic, and its sedimentary facies is granular beach. The lithology of the parent rock is sandclastic limestone, oolitic limestone, conglomerate limestone and a small amount of microcrystalline limestone. The main mineral composition of parent rock and cavernous secondary sediments is low magnesium calcite (LMC,low magnesium calcite).) The lower Mg/Ca of parent rock leads to lower Mg/Ca of cavern water, which makes the low magnesium calcite crystal, which is composed of secondary sediments, grow rapidly laterally, and leads to pure, coarse and high degree of automorphism of calcite crystal. The stable interbeach marine sedimentary environment during the sedimentary period of the top and bottom strata of the Xueyudong mother rock is helpful to the formation of high strength thick layer microcrystalline limestone and thus provides an effective support for the development of cave system. This indicates that the sedimentary geological characteristics of the cave parent rock will have a significant impact on the development of the cave system and the characteristics of the cave secondary sediments at the level of the material basis.
【作者单位】：西南大学地理科学学院;中国石油天然气股份有限公司青海油田分公司勘探开发研究院;中国石油天然气股份有限公司青海油田分公司测试公司;暨南大学地下水与地球科学学院;
【基金】：资助项目:喀斯特槽谷区土地石漠化过程及综合治理技术研发与示范(2016YFC0502300)
【分类号】：P512.2

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