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211.
贵州桐梓松坎剖面中、下三叠统发育齐全,化石丰富,出露良好,是研究上扬子地区海相地层的理想剖面之一。根据地层划分与对比,将其分为下三叠统夜郎组、茅草铺组和中三叠统关岭组。该剖面以碳酸盐岩和碎屑岩为主,其中碳酸盐岩占67%,在夜郞组、茅草铺组和关岭组均有分布;碎屑岩占24%,主要分布于夜郎组。研究表明,松坎剖面中、下三叠统是一套多旋回沉积,其中夜郎组包括2个海进海退旋回,属于潮坪、开阔台地和浅滩沉积环境;茅草铺组包括3个海进海退旋回,属于开阔台地和局限台地沉积环境;关岭组总体上为海退沉积,属于局限台地和潮坪沉积环境。在沉积环境分析的基础上,建立了松坎剖面中、下三叠统的沉积模式,即潮坪-局限台地-浅滩-开阔台地沉积模式。 相似文献
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Jun Chen Tyler W. Beatty Charles M. Henderson Harry Rowe 《Journal of Asian Earth Sciences》2009,36(6):442
Several continuous Permian–Triassic boundary (PTB) sections are well exposed in the interior of the Great Bank of Guizhou (GBG) on the east limb of the Bianyang syncline, Luodian County, Guizhou Province, South China. Fourteen conodont taxa are identified, including Clarkina kazi, Clarkina lehrmanni n. sp., Clarkina taylorae, Clarkina zhejiangensis, Hindeodus eurypyge, Hindeodus inflatus, Hindeodus sxlatidentatus, Hindeodus parvus erectus, Hindeodus parvus parvus, Hindeodus postparvus, Hindeodus praeparvus, Hindeodus typicalis, Isarcicella staeschei, and Merrillina ultima based on a detailed study of the Permian-Triassic interval at the Dawen section. The first occurrence (FO) of H. parvus parvus in the lower Daye Formation, at about 7.45 m above the contact surface between the Upper Permian skeletal packstone and a calcimicrobial framestone unit, is correlated with the Permian–Triassic boundary; the occurrence of H. eurypyge, H. praeparvus and M. ultima immediately below and H. postparvus above the interval supports this interpretation. A morphometric analysis of 31 Hindeodus specimens helped distinguish H. parvus erectus from H. parvus parvus and H. postparvus. Correlation with the Meishan section (PTB GSSP) using both conodont biostratigraphy and carbon isotopes, indicates that the major extinction at the two localities is simultaneous and coincides with the top of the skeletal packstone at Dawen. The contact between the skeletal packstone and the calcimicrobialite is very irregular and has previously been interpreted as a dissolution surface and correlated with a surface in the lower part of bed 27 at Meishan. Our results confirm this interpretation and reveal that the dissolution event postdated the extinction. 相似文献
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以深圳市电信管线断面详查工程为背景,论述了电信管线断面详查的要求、方法、技术和内容,以将成果融入深圳市规划国土局地下管线管理信息系统为目标,讨论了电信管线断面图形数据库的设计与建立. 相似文献
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《International Geology Review》2012,54(10):1184-1202
Based on metamorphic studies of the Yadong high-pressure (HP) granulite and multiple thermochronological investigations of granitoids from both upper and lower parts, the Yadong section in the eastern Himalaya constrains the Cenozoic tectonic evolution of the Greater Himalayan Sequence (GHS). The Yadong HP granulite, located at the top of the GHS, underwent a peak-stage HP granulite facies metamorphism and two stages of retrograde metamorphism. Granulite and hornblende facies retrograde metamorphism took place at 48.5 and 31.8 Ma, respectively, marking the time of exhumation of the subducted Indian slab to lower and middle crustal levels. Subsequently, an average young zircon U–Pb age obtained from the Yadong HP granulite indicated that this unit was captured by its surroundings in a partially molten condition at 16.9 Ma. In addition, three granitoids from both the lower and the upper parts of the GHS yielded biotite 40Ar/39Ar ages of 11.0, 11.3, and 11.5 million years. These consistent ages suggest that the GHS along the Yadong section was laterally extruded and synchronously cooled to ~300°C at ~11.3 Ma. Furthermore, the granitic gneisses yield apatite fission track ages of ~7 million years, documenting the cooling of the GHS to ~110°C. A two-stage model describes the Cenozoic tectonic evolution of the GHS: (1) the Indian slab had subducted under Tibet before ~55 Ma, and was exhumed to the lower crust (50-40 km) at 48.5 Ma, and to the middle crust (22-15 km) at 31.8 Ma; and (2) the partial melting occurred at middle crustal levels during the period 31.8 to 16.9 Ma, causing channel flow. In the late stage, the GHS was laterally extruded by ductile mid-crustal flow during the period 16.9 to ~7 Ma, characterized by a fast cooling rate of ~2 mm per year. 相似文献
219.
滇西北兰坪盆地北部上三叠统含盐层位的厘定及其意义 总被引:1,自引:0,他引:1
通过野外实测剖面和大量室内岩矿工作,首次指出兰坪盆地上三叠统至少存在2套含盐层位,上含盐层位于三合洞组上段(T3s2),盐类物质以石膏、天青石为主,下含盐层位于三合洞组下段(T3s1),以天青石为主。天青石和石膏均呈中厚层层状产出,与顶底板地层产状一致。不同地区含盐层岩石组合及序列不同,横向上不具有可对比性,提出其并非正常蒸发沉积产物的认识。同时,含盐地层又是盆地内铅锌矿重要的赋矿层位,因此上三叠统含盐建造层序的厘定对深化认识区域铅锌矿床成矿机制、指导盐类矿床和铅锌矿找矿具有重要的意义。 相似文献
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对拟建设的新疆且末地磁台进行场址勘选,采取十字剖面测量和密跨度测量方法进行地磁场总强度F测量,对测量结果进行初步分析.分析结果表明,且末地磁台的地质条件、磁场梯度分布和背景噪声环境等地磁观测环境条件,符合国家地磁台建设规范的要求,适宜地磁基准台站建设. 相似文献