【作者】 罗宇鹏；

【导师】 王训练； 张海军；

【作者基本信息】 中国地质大学（北京） ， 古生物学与地层学， 2010， 硕士

【摘要】 本文研究阿克塞钦湖地区晚白垩世铁隆滩群碳酸盐岩特征及意义,取得了以下主要认识:1.详细研究了铁隆滩群的岩石学特征。铁隆滩群主要由碳酸盐岩组成,其次为碎屑岩和石膏,此外极偶尔还见少量凝灰岩夹层。将该区铁隆滩群碳酸盐岩进一步分为颗粒-基质灰岩类、生物灰岩/礁灰岩类以及白云岩-灰岩过渡类型和灰岩-碎屑岩过渡类型。2.研究了铁隆滩群沉积相特征,将铁隆滩群的沉积相划分为碳酸盐台地、台缘-斜坡和陆棚三个相区,其中主要为碳酸盐台地相,包括局限台地、开阔台地2个沉积相带,每个相带又包括若干亚相和不同的岩石微相类型。3.研究了铁隆滩群碳酸盐岩沉积环境演化,在这一演化过程中总体上表现为两个海平面升降旋回。铁隆滩群沉积早期为局限台地环境,其中主要以具明显周期性潮汐活动为主,随后开始出现首次海进,沉积环境以开阔台地相中的台内滩为主,海进时间较短。铁隆滩群沉积中期发生海退,沉积环境逐渐变为局域台地相,随后发生第二次海进,一直持续到整个铁隆滩群沉积结束,沉积环境主要以开阔台地相中的台内滩为主。4.元素地球化学表明,研究区晚白垩世Turonian-Campanian期间的浅水碳酸盐岩旋回层红色调灰岩形成于相对更强氧化环境,Fe³⁺很可能是造成该区碳酸盐岩呈红色的主要原因。5.同位素地球化学表明,研究区晚白垩世Turonian-Campanian期间浅水碳酸盐岩的δ¹³C值普遍偏高,认为其主要要原因是白垩纪OAE时期,大量的有机碳被快速埋藏造成的,可能还与白垩纪OAE时期古海洋的分层结构及其碳同位素分馏作用有关。氧同位素分析显示研究区在晚白垩世Turonian-Campanian时期温度总体呈升高趋势。更多还原

【Abstract】 The Akesaiqin Lake area, between Karakorum and west Kunlun Mountains, northwest Tibet, is one of the areas in China where the Late Cretaceous marine strata are well developed. The Upper Cretaceous in studied area, named Tielongtan Group, is distributed in Mesozoic fault basins along E-W or SEE-NWW direction. It forms a series of shallow-marine and littoral deposits and a little terrestrial clastic rock overlying unconformably Carboniferous fine clastic rocks or Jurassic carbonate rocks.1. A detailed study in characteristics of the rock of Tielongtan group shows: Tielongtan group is composed of carbonate rocks, which predominates in the group, clastic rocks and gypsum followed, and very occasionally to see little tuff interlayer. Carbonate rocks of Tielongtan group in the area can be further divided into several types: particle - matrix limestone, bioclastic limestone / reef limestone, dolomite - limestone peperite and limestone - clastic rocks peperite.2. A study in sedimentary facies of Tielongtan group shows: According to the rock types, fossil assemblage and sedimentary structure, the types of sedimentary facies in the Tielongtan Group in study area include restricted platform facies, open platform facies. Each phase is consisting of several different rock facies and microfacies3. A study of the evolution of carbonate sedimentary environment of Tielongtan group shows: in the evolution of the overall performance have two marine transgressions. In the early-term of deposition of Tielongtan group, the sedimentary facies in study area is mainly restricted platform facies. Subsequently, the first transgression started in the study area, the sedimentary facies in study area is mainly open platform facies, and the time of the first transgression is short. In the medium-term of deposition of Tielongtan group, the second marine transgression occurred, and until the end of the Tielongtan group. In this time, the sedimentary facies in study area is mainly open platform facies.4. The elemental geochemistry characteristics indicate that the Late Cretaceous Turonian-Campanian shallow-water red-white carbonate cycles was formed in a relatively more oxidizing environment. The red colour is mainly due to presence of hematite pigment.5. Isotope geochemistry characteristic show that theδ¹³C values of the Late Cretaceous Turonian-Campanian shallow-water carbonate rocks are generally high, that the main reason for this is caused by a large number of organic carbon rapid burial, during the period of the Cretaceous OAE.更多还原