摘要
岩溶作用改变了原始碳酸盐沉积物(岩)的化学成分,因此地球化学特征可以作为鉴别古岩溶的重要依据。山西省兴县奥陶系马家沟组第五段第一亚段(马五_1)沉积于低能的、局限的、盐度较高的陆表海环境,基本上是经过岩溶作用长期改造的碳酸盐岩。根据分析118个样品的CaO,MgO,SiO_2,Al_2O_3,Fe_2O_3,Na_2O,K_2O,Co,Ba,Zr,Zn,V,Th,Ti,Si,P,Ni,Mn,La,Ce,Cu,Cr,Li,Se,U,B含量,得出沉积作用、岩溶作用、埋藏成岩作用控制着岩石的地球化学成分。其中岩溶作用起着最重要的作用。在这些作用的共同影响下,马五_1地层中有高的SiO_2,Al_2O_3,Fe_2O_3,Na_2O,Ba,Ti,Ce,Li含量,有略高的Th,Ni,Cu,Cr,La含量,有低的MgO,K_2O,Sr,P,Mn含量。
Karstification changes the chemical composition of original carbonate sediments/rocks; therefore geochemical characteristics may serve as important grounds for identification of palaeokarst.The first submember of the fifth member of the Lower Ordovician Majiagou Formation (M5_1) in Xingxian,Shanxi Province,which was deposited in shallow and confined epicontinental environments with low energy and high salinity,consists of carbonate rocks modified by palaeokarstification for a long period.In the light of contents of CaO,MgO,SiO_2,Al_2O_3, Fe_2O_3,Na_2O,K_2O,Co,Ba,Zr,Zn,V,Th,Ti,Si,P,Ni,Mn,La,Ce,Cu,Cr,Li,Se,U and B of 118 samples from M5_1,it may be concluded that sedimentation,karstification,and burial diagenesis controlled the geochemical composition of carbonate rocks,of which karstification played the most important role.As a result of the combined effects of sedimentation,karstification, and burial diagenesis,there are high values of SiO_2,Al_2O_3,Fe_2O_3,Na_2O,Ba,Ti,Ce and Li,higher values of Th,Ni,Cu,Cr and La,and low values of MgO,K_2O,Sr,P and Mn in the M5_1.
出处
《地质论评》
CAS
CSCD
北大核心
1996年第S1期62-69,382,共9页
Geological Review
关键词
地球化学特征
古岩溶
奥陶系
山西兴县
geochemical characteristics
paleokarst
Ordovician
Xingxian
Shanxi province
