龙门山造山带构造地层学研究

龙门山造山带属青藏高原东缘的陆内造山带 ,是一个独立的地层复合体 ,地层记录具有复杂性、混杂性、不连续性、不完整性和分带性等特征 ;根据龙门山造山带地层的构造变形、变位和变质特征以及边界断裂特征 ,可将龙门山造山带划分为 A、B、C三个构造地层带 ,其中 A带位于青川—茂汶断裂与北川—映秀断裂之间 ,属变形变质构造地层带 ,主要由志留系—泥盆系浅变质岩和前寒武系杂岩构成 ;B带位于北川—映秀断裂与彭灌断裂之间 ,属变形变位构造地层带 ,主要由上古生界—三叠系沉积岩构成 ;C带位于彭灌断裂与广元—大邑断裂之间 ,属变形构造地层带 ,主要由侏罗系至第三系红层构成。对不同类型构造地层带采用了不同的地层学研究方法 ,并建立了各个构造地层带的独立的地层系统 ,其中 A带采用构造—地 (岩 )层分析方法 ,B带采用构造片—地层分析方法 ,C带采用构造层序地层分析方法。

Tectostratigraphy of Longmenshan Orogen

Longmenshan orogen is an intracontinental orogen on the eastern margin of the Xizang plateau. There are three types of tectostratigraphic zones to be recognized in this complicated tectonic collage based on characteristics of deformation, displacement and metamorphism of strata. Zone A, lying between the Qingchuan Maowen fault (F 1) and Beichuan Yingxiu fault (F 2), is a tectostratigraphic zone of deformation and metamorphism and mainly composed of Silurian to Dvernian epmetamorphic rocks and Precambrian complex. Zone B, lying between the Beichuan Yingxiu fault (F 2) and Pengxian Guanxian fault(F 3), is a tectostratigraphic zone of deformation and displacement and consists of Palaeozoic to Triassic rocks . Zone C, lying between the Pengxian Guanxian fault (F 3)and Guangyuan Dayi fault(F 4), is a tectostratigraphic zone of deformation and consists mainly of Jurassic to Neogene strata. Three different types of tectostratigraphic methodology has been applied to establish original stratigraphic succession of each tectostratigraphic belts, including tectono sequence stratigraphy, tectonic slice stratigraphy and tectostratigraphy(lithostratigraphy).