沉积岩中稳定重砂矿物的成岩蚀变特征及其指示意义  

Diagenesis Alteration of Heavy Minerals of Garnet,Zircon,Rutile,Apatite,Tourmaline and Titanite during Diagenesis and Its Geological Significance

作　　者：刘嵘[1] 董月霞[2] 谭靖[1] 张素新[3] 

机构地区：[1]中国地质大学地球科学学院,武汉430074 [2]中国石油天然气股份有限公司冀东油田公司,河北唐山063004 [3]中国地质大学地质过程与矿产资源国家重点实验室,武汉430074

出　　处：《地质科技情报》2007年第6期10-16,共7页Geological Science and Technology Information

基　　金：中国石油天然气股份有限公司冀东油田公司科研项目"南堡凹陷东营组沉积体系;盆-源耦合及成藏贡献研究"

摘　　要：结合矿物物理化学特征解释了沉积岩中常见的稳定重砂矿物石榴石、锆石、金红石、磷灰石、电气石和榍石的碎屑形态和稳定性;借助扫描电镜下呈现出来的形貌特征,如溶蚀、裂开、圆化程度等,分析了控制稳定重砂矿物蚀变作用的物理化学因素;认为稳定重砂矿物之间的相对稳定性受沉积环境和成岩条件的控制。在同生和成岩过程中,有机酸参与的流体可以改变部分稳定重砂矿物(如磷灰石、石榴石、电气石)的稳定性,并导致其分解,因此稳定重砂矿物的蚀变特征一方面可以辅助解释重砂矿物组合的空间变化,另一方面还可以揭示沉积过程中的气候条件、植被发育程度,从而指示沉积相,并约束成岩过程中流体的化学性质;此外,导致稳定重砂矿物溶蚀的流体对于其他造岩矿物的影响以及对次生孔隙的贡献程度值得进一步研究。The general shape and stability of six common elastic heavy minerals of garnet, zircon, rutile, apatite, tourmaline and titanite are discussed based on their physical properties and chemistry. This paper focuses on surface characteristics, such as etched pits, cleavage and rounded level with an effort to make clear the possibility and degree of dissolution once happened on different heavy minerals. It is found that the relative stability between heavy minerals during diagenesis is changeable with depositional environment. Groundwater, where organic acid accommodates, can modify stabilities of some heavy minerals, such as apatite, garnet and tourmaline, and results in dissolution of these minerals. Therefore, alteration characteristics of heavy minerals can be used to explain spacial variation of heavy mineral assemblages, and as indicators of depositional environment. On the other hand, it is very important to notice that organic acid bearing fluid, which can even dissolve stable heavy minerals, should affact other rock forming minerals either, and contributes to secondary porosity, thus is worthy of being investigated further more.

关 键 词：重砂矿物 沉积相分析 溶蚀 成岩作用 次生孔隙 

分 类 号：P571[天文地球—矿物学]