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针对四川盆地北部上三叠统须家河组硅质砾岩外表单调的物理特性和物源难以明确区分的问题,利用阴极发光技术对米仓山—大巴山前缘9条须家河组砾岩剖面中采集的砂砾岩和胶结物共计36块样品,127片薄片进行砾石和砂级碎屑组分详细的对比分析。结果表明须家河组硅质砾岩中石英质砾石主要有两种阴极发光类型:1以紫光、蓝光为主,变化于蓝-紫、红-紫之间,占40.2%~84.5%,平均为67.97%,其中紫色光占3.2%~13.04%,红色光占3.8%~13%,蓝色光占16.7%~33.3%,蓝紫色光占8.7%~37.5%,紫红色光占17.5%~22.6%,主要来自于岩浆岩(1%~15%),变质岩(40%~80%),主要分布于万源-南江一带;2不发光,占15.49%~59.79%,平均为32.03%,主要来自于沉积-成岩成因的石英(燧石),主要分布于旺苍-金溪,呈现出由东到西递减的趋势。揭示须家河组硅质砾石尽管成分单一,但其硅质来源具有明显的差异,来源于岩浆岩、变质岩、沉积岩等不同的母源。综合分析认为四川盆地北部须家河组砾岩沉积时期存在三大源岩体系,具有明显的多源性。秦岭造山带是川北地区须家河组的主要物源供给区。研究结果亦证明,阴极发光分析方法可作为沉积岩物源分析的一种有效手段。
Aiming at the problem that the monotonous physical properties and provenance of siliceous conglomerate of the Upper Triassic Xujiahe Formation in the northern Sichuan Basin are difficult to distinguish clearly, the gravitropism of 9 Xujiahe Formation in the front of Micangshan-Daba Mountains by cathodoluminescence A total of 36 samples of gritstone and cements collected in the rock profile and 127 thin slices were used to conduct a detailed comparative analysis of the gravel and sand fraction components. The results show that there are mainly two types of cathodoluminescence in the quartz gravels in the Xujiahe Formation silicic conglomerate: 1 mainly consists of violet and blue light, varying between blue-purple and red-purple, accounting for 40.2% -84.5%, with an average of Is 67.97%, of which purple light accounts for 3.2% ~ 13.04%, red light accounts for 3.8% ~ 13%, blue light accounts for 16.7% ~ 33.3%, blue violet light accounts for 8.7% ~ 37.5% and purple light accounts for 17.5% ~ 22.6 %, Mainly from magmatic rocks (1% -15%) and metamorphic rocks (40% -80%), mainly distributed in Wanyuan-Nanjiang area. 2 Non-luminescence accounts for 15.49% -59.79% with an average of 32.03% Mainly from sedimentary-diagenetic quartz (flint), mainly distributed in Wangcang-Jinxi, showing a decreasing trend from east to west. It is revealed that the siliceous gravel in Xujiahe Formation has a significant difference in the source of siliceous rock, although originates from magmatic rocks, metamorphic rocks and sedimentary rocks, despite their simple composition. The comprehensive analysis shows that there are three major source rock systems during the conglomerate deposition in the Xujiahe Formation in the northern Sichuan Basin, with obvious multi-source. The Qinling orogenic belt is the main source of supply for Xujiahe Formation in northern Sichuan. The results also prove that the cathodoluminescence method can be used as an effective means of sedimentary source analysis.