Diagenesis and Metamorphism of Triassic Flysch Along Profile Zoigê‐Lushan, Northwest Sichuan, China
Diagenesis and Metamorphism of Triassic Flysch Along Profile Zoigê‐Lushan, Northwest Sichuan, China
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DOI：
10.1111/j.1755-6724.2008.tb00647.x
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发表时间：
2008-08
期刊：
影响因子：
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通讯作者：
Wang Hejing;M. Rahn;Tao Xiao-feng;Zheng Nan;Xu Tingjing
中科院分区：
文献类型：
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作者：
Wang Hejing;M. Rahn;Tao Xiao-feng;Zheng Nan;Xu Tingjing
利用伊利石和伊利石堆积、指标矿物、矿物组合、白色云母多型和晶畴大小、电子探针分析（EMPA）、b 0地质压力计和B 0地质温度计等方法，对松潘-甘孜造山带若尔盖-芦山剖面三叠系复理石建造的成岩和变质叠加作用进行了定量研究。根据所获得的数据，确定了两个锚定带、两个表带、一个成岩带和它们之间的过渡带。伊利石结晶度与云母的最佳平均晶畴尺寸密切相关，与微晶度适度相关。在浅成带中观察到2 M1白色云母多型体，而在浅成带和成岩带中观察到2 M1和1 M多型体。浅成变质作用在低压至中压条件下达到最高温度370°C±21°C。粘土矿物在变质作用中经历了奥斯特瓦尔德熟化作用。龙门山断裂两侧的岩石显示出不同程度的变质叠加：在龙门山断裂的西北侧，浅变质条件与东南侧的成岩条件形成对比。
We used illite and chlorite crystallinities, index minerals, mineral assemblages, polytype and domain size of white mica, electron microprobe analysis (EMPA), b0 geobarometer and chlorite geothermometer to quantify the diagenetic and metamorphic overprint on the Triassic flysch formations in the Songpan‐Garzê orogen along profile Zoigê‐Lushan, northwest Sichuan. Two anchizones, two epizones, one diagenetic zone and a transition belt in‐between them are defined on the basis of the obtained data. Illite crystallinity correlates strongly with the best mean domain size of mica and moderately with chlorite crystallinity. 2M1 white mica polytype are observed within the epizone whilst 2M1 and 1M polytypes occur in the anchizone and diagenetic zone. Epizonal metamorphism reached maximum temperatures of 370°C±21°C at low‐to intermediate pressure conditions. Clay minerals underwent Ostwald ripening during metamorphism. Rocks from both sides of the Longmenshan fault reveal contrasting degrees of metamorphic overprint: on the northwest side of the Longmenshan fault, epimetamorphic conditions contrast with diagenetic rocks on the southeast side.