马岭地区嘉陵江组沉积环境演化分析:来自沉积学和主微量元素的证据

马岭地区位于贵州省兴义市，其沉积地层经历了二叠纪-三叠纪之交的沉积环境演化，是研究早三叠世沉积环境变化的理想地区。通过对马岭地区嘉陵江组的野外踏勘，以获得的实测剖面资料为基础，结合室内薄片观察，并根据14种主微量元素的结果，进而探讨其沉积环境的演变。马岭河剖面主要出露碳酸盐岩与碎屑岩，可分为四段，共取16件岩石样品进行送样分析，结合沉积相、古气候指标SiO₂/Al₂O₃比值和古盐度指标，古水深指标CaO/MgO、Sr/Ba比值，可指示马岭地区在早三叠世经历了如下变化:①由异常炎热、干燥气候逐渐过渡为整体湿润的气候，这可能为早三叠世及后期生物复苏提供了适宜的气候条件；②发生浅海、深海的交替变化。嘉陵江组一~四段分别以开阔台地相、潮坪相、开阔-局限-开阔台地相、局限台地相沉积为主，每段的古盐度变化、海平面升降等现象，加上腹足、双壳等生物碎屑的局部出现，印证了该区早三叠世海洋环境异常多变，并具有多期次恶化-改善的演化过程。 

Sedimentary environment evolution of the Jialingjiang Formation in the Maling area: Evidence from sedimentology and major and trace elements

The Maling area is located in Xingyi City, Guizhou Province.It is an idea area to study the evolution of the sedimentary environment in the Early Triassic for its sedimentary strata saddle the Permian and Triassic transition.Based on the integrations of field survey of the Jialingjiang Formation in this area, measured profile data, microscopic observation in the laboratory, and 14 major and trace elements, the evolution of its depositional environment was discussed.Carbonate rocks and clastic rocks are mainly exposed in Maling area, which can be divided into four members.A total of 16 rock samples were collected for analysis.Combined with sedimentary facies, palaeoclimate index (SiO₂/Al₂O₃ ratio), paleosalinity index, paleobathymetric index (CaO/MgO and Sr/B aratio), the following changes are identified in the Early Triassic: ① The abnormally hot and dry climate gradually transitioned to an overall humid climate, which may be the result of the Early Triassic and the biological recovery provided suitable climatic conditions; ②The alternation of shallow sea and deep sea occurred. The first to fourth members of the Jialingjiang Formation are dominated by open platform facies, tidal flat facies, open-limited-open platform facies, and limited platform facies, respectively. The local appearance of bioclasts such as bivalves confirms that the Early Triassic marine environment in this area was abnormally variable and had multiple stages of deterioration-improvement evolution.