论文部分内容阅读
厄瓜多尔奥连特盆地白垩系Napo组UT段发育一套分布广泛的富含海绿石的硅质碎屑岩,针对海绿石的岩相、矿物学、地球化学及时空属性进行分析,可以揭示海绿石的组分、成熟度、形成及成因类型,结合地质约束有助于理解其形成的沉积地质意义.利用偏光显微镜、X射线衍射、电子探针及Qemscan对海绿石矿物的岩相、矿物组成和主量元素进行系统地分析.暗绿色、呈弯曲玫瑰花状的海绿石具有高的K2O含量(平均值为8%,质量百分比),是形成于海相低沉积速率环境的高演化成熟型海绿石云母矿物或狭义范畴的海绿石.化学组分和时空属性揭示研究层段的海绿石经历了一定程度风暴流和/或潮汐流作用的搬运改造,属于层内准原地海绿石.UT段海绿石含量向上的增大趋势和成熟度的变化,以及横向上从盆地东部斜坡区埋深2~3km到西部盆缘露头区相距约120km的海绿石在形态和化学成分上具有相似性,指示其主要是层内准原地海绿石的特点.UT段垂向上海绿石含量增大的趋势同时反映外陆棚物源区原地海绿石向岸方向的短距离迁移,反映了相对海平面持续上升的海进过程;而且同时期海绿石平面上的广泛分布指示沉积时期的环境属于构造稳定的陆表海.
In the UT section of the Cretaceous Napo Formation in the Oriente Basin, Ecuador, a set of widely distributed pyrochlore-rich siliciclastic rocks are developed. The analysis of lithofacies, mineralogy, geochemistry and spatio-temporal properties of glauconite reveals The composition, maturity, formation and genetic type of glauconite can help to understand the sedimentary geological significance of the formation.Using polarized microscope, X-ray diffraction, electron probe and Qemscan to analyze the lithofacies , Mineral composition and major elements of the system.A dark green, curved rosette-shaped glauconite with high K2O content (average 8%, mass percentage) is formed in the low marine sediment rate environment Evolving matospinite or plagioclase in the narrow sense.Chemical composition and spatio-temporal properties reveal that the glauconite in the study interval has undergone a transgression of storm flow and / or tidal flow to some extent within the horizon The upward trend and maturity of the upland glauconite-UT segment in the upper part of the glauconite, and the variation of the glauconite laterally from the depth of 2 ~ 3 km in the eastern slope of the basin to about 120 km away from the outcrop area in the western basin margin Morphology and The similarities in composition indicate that it is mainly characterized by the quasi-original glauconite within the layer.The upward trend of the green stone content in the vertical section of the UT section also reflects the direction of the inland source of the outcrop source The short-distance migration reflects the sea-level process of relative sea level rising continuously. In the mean time, the wide distribution on the glauconite plane indicates that the sedimentary environment belongs to the stable land surface sea.