辽河盆地西部凹陷粘土矿物的成岩作用研究

对辽河盆地西部凹陷兴隆台、马圈子、欢喜岭和曙光等地沙河街组不同深度的层位,高升地区(属弱碱性和弱氧化-弱还原环境的沙四段分别采样,经X-光衍射、电子显微镜、化学分析和差热、红外等项目的分析鉴定,研究区内的粘土矿物有: 蒙脱石 在全区较浅的地层(如欢喜岭地区小于1000米,兴隆台地区小于1500米)中均有分布。其主要成份为二八面体的钙蒙脱石。 皂石 为黑色橄榄-辉石玄武岩的次生产物。

STUDY ON DIAGENESIS OF CLAY MINERALS IN THE WESTERN DEPRESSION OF THE LIAOHE BASIN

Different clay mineral assemblages and their replacement have been formed in different sedimentary and diagenetic environments in the western depression ( Huan-xiling, Xinglongtai and Maquanzhi ): 1.Montmorillonite-I/M-illite-kaolinite mineral assemblage 2.1/M-authigenic illite-atlthigenic chiorite mineral assemblage The weak acidic and weak alkaline environments were transformed into slight alkaine-weak reductive ones with the increase of depth and geothermal and mont-morillonite and I/M turned into illite and trioctahedron chlorite. In the north region of the western depression ( Gaosheng and the local area of Shuguang)t 1. I/M-illie mineral assemblage 2. Glauconite-trioctahedron smectite mineral assemblage 3. Fe-saponite mineral The Sha-4 stage in the area was a slight alkaline-weak reductive sedimentary environment without kaolinite mineral and Ca, Fe3 + Fe2+and Mg were rich in the environment due to the degeneration of the secondary saponite from basalt into trio-dioctahedron smectite. Together with Fe and Mg, K and Al supplied by solubilized K and Al-bearing terrigenous minerals under the higher geothermal moved into I/M crystal lattices and thus forming glauconite. The evidence of mineralogy has shown that the geochemical properties of the sedimentary and diagenetic environments are the principal factors which control low-temperature geochemial behaviors of clay minerals during the diagenesis, and secondly, the temperature also plays an important part during the diagenesis of clay minerals.