Detrital composition of Tiesiao Formation and Liangjiehe Formation of Nanhua System in Songtao Highland of the northeastern Guizhou Province and tectonic setting of its source regions
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摘要: 雪峰运动的构造属性一直存在较大争议。统计黔东北松桃高地南华系铁丝坳组和两界河组的陆源碎屑组分,并应用Dickinson三角图解原理进行分析。研究结果显示: 铁丝坳组和两界河组沉积时期陆源碎屑的物源主要来自火山弧源区和再旋回造山带,伴随有火山活动; 铁丝坳组的碎屑成分成熟度较低,主要投点在火山弧物源区,显示了近源剥蚀、搬运堆积的特征,两界河组的石英矿物屑含量比铁丝坳组高,趋向于再旋回造山带物源; 碎屑组分中岩屑的岩性组合为玄武岩、安山质玄武岩、粗面岩、凝灰岩、熔结凝灰岩、流纹岩、长英质糜棱岩等,表明在铁丝坳组和两界河组沉积时期或沉积之前,研究区就已进入陆内裂陷和板内造山的大地构造背景。研究可为该地区雪峰运动的构造属性提供微观证据。Abstract: The tectonic properties of Xuefeng movement has significant controversies. This study anglyzed the terrigenous detrital composition of Tiesiao Formation and Liangjiehe Formation of Nanhua System in Songtao Highland of the northeastern Guizhou Province, using Dickinson triangle diagrams theory. The results show that the terrigenous detrital source mainly comes from arc orogen sources and recycled orogen provenances, accompanied by volcanic activities. The maturity of the detrital components in Tiesiao Formation is relatively low, and the components mainly landed around the volcanic arc source area, showing the characteristics of near erosion and transporting accumulation. The quartz content in Liangjiehe Formation is higher than that in Tiesiao Formation, which lands in the recycled orogen provenances. The detrital composition contains basalt, andesitic basalt, trachyte, tuff, ignimbrite, rhyolite, felsic mylonites and so on, indicating that intracontinental rift and intraplate orogenic mechanism occurred during or before the sedimentation of Tiesiao Formation and Liangjiehe Formation in the study area. This research could provide some microscopic evidence for tectonic attribute of Xuefeng movement.
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