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扬子地台北缘在寒武纪筇竹寺期—沧浪铺期出现海退,该时期的仙女洞组属浅海碳酸盐岩与碎屑岩的混合沉积单元,分布于陕西南部及四川北部。陕南南郑福成和碑坝剖面组成完整仙女洞组序列,其中包含8期生物礁相单元。单层礁体为米级厚度,形态特征显示丘状隆起或平缓延伸。水体的清澈度、深度以及水动力强度变化对各期礁相单元生长的控制力度因时而异,陆源碎屑数次侵入导致海水浑浊度增高,点断了礁体生长。礁灰岩微相类型包括钙质微生物粘结岩、古杯-钙质微生物绑结岩、古杯漂砾-砾屑灰岩、粒泥状-泥粒状灰岩以及泥状灰岩。早期礁灰岩中钙质微生物粘结岩含量丰富,之后古杯绑结岩在礁灰岩构建中具有丰度增长的趋势,且上部礁灰岩层位中不规则古杯占主要地位。仙女洞组沉积晚期海水变浅和水动力条件增强,常见漂砾灰岩和砾屑灰岩。
The northern margin of the Yangtze platform developed during the Cambrian Qiongzhu period-Canglang formation, and the fairy cave belongs to the mixed sedimentary units of shallow sea carbonate rocks and clastic rocks in southern Shaanxi and northern Sichuan. South Shaanxi section of Fucheng and Bei dam profile complete fairy cave group sequence, which contains 8 reef phase units. The monolayer reef is of rice thickness, and the morphological features show mound bulge or gentle extension. The intensity of water body clarity, depth and hydrodynamic strength change control the unit cell growth of various stages of reefs from time to time. Several times intrusion of terrigenous debris leads to the increase of turbidity of seawater and the discontinuous growth of reefs. Reef limestone microfacies types include calcareous microbial bond rock, ancient cup-calcareous microbial binding rock, ancient beaker boulder-conglomerate limestone, grainy-mud granular limestone, and muddy limestone. In the early reef limestone, the content of calcareous microbial binding rock was rich. After that, the ancient cupbound lithic rock showed a trend of abundance growth in reef limestone, and the irregular ancient cup in the upper reef limestone dominated. In the fairy cave group, the sea water became lighter and the hydrodynamic conditions were enhanced later in the sedimentary period. Common boulder limestone and gravelly limestone.