摘要
四川盆地北部地区以下三叠统嘉陵江组四段—五段的大套膏岩层为分割层,将其分为上下两个构造层,上构造层断裂以膏岩层作为主滑脱层,上、下构造层断裂均终止于膏岩层。区内东部构造运动最为强烈,断裂非常发育。中部地区上构造层断裂相对发育,下构造层不发育。西部受构造运动影响最小,断裂不发育。断裂样式主要表现为"Y"或反"Y"字型组合、"树枝状"、平行及对冲断裂等。三叠系主要在平昌—达州—宣汉一带发育北东—南西向断裂,通江以东地区以北西—南东走向为主,中部平昌—龙岗一带受力复杂,断裂走向较不规律,元坝地区发育有南北走向断裂,往西断裂逐渐不发育。全区可划分为7大构造带,其中米仓山前缘褶皱构造带包含了西部九龙山背斜和东部通南巴构造;川北凹陷构造带仅在上构造层有少量断裂发育;川北平缓构造带上构造层发育大量中小型断裂;大巴山前陆盆地构造带属于断褶发育的凹陷带;川东高陡构造带构造变形强烈,上构造层多发育披覆背斜及较陡断背斜,下构造层发育断背斜并伴有断堑、断垒特征。该地区下构造层断裂发育开始于印支早期构造运动,印支中后期断裂活动进一步加强;上构造层断裂发育始于印支中后期构造运动,盆地北部整体开始抬升使雷口坡组顶部遭受剥蚀;燕山期上、下构造层断裂进一步发育,山前褶皱构造带挤压变形强烈,构造格局基本定型,喜马拉雅山期运动对研究区构造具有叠加改造作用。
In northern Sichuan Basin,it is divided into upper and lower structural layer by large set of gypsum of Lower Triassic Jialingjiang Formation 4th -5th section. At the upper structural layer, gypsum is the main decollement. And faults of upper and lower structural layers terminate in the gypsum. In eastern, tectonic movement is most intense, faults are very developmental. In the central region, faults are relative developmental in the upper structural layer and non developmental in the lower layer. The western part have minimal impact of tectonic movement with non developmental faults. There are some main fault styles,such as the ＂Y＂ or anti-＂Y＂ combination,branching, parallel and ramp faults. Triassic developed NE-SW trending faults in Pingchang-Dazhou-Xuanhan area, NW-SE trending faults in the east area to Tongjiang, irregular trending faults in Pingchang-Longgang area in where it suffered complicated forces, N-S trending faults in Yuanba area, and gradually non developmental fault in the western part. The region can be divided into seven major tectonic belt. Micang-Mountain front folded belt contains Jiulong-Mountain anticline in western and Tongnanba structure in eastern. Northern Sichuan depression just have a small amount of faults in the upper layer. Northern Sichuan gentle belt have a large number of small and medium-sized faults in the upper layer. Eastern Sichuan high- steep structure deforms strongly, upper layer mainly developed drape anticlines and steep anticlines, and lower layer developed faulted anticline with fault grabens and fault horsts. The faults＇ development of lower structural layer began in the early Indosinian Movement, its activity has been further strengthened in the Mid-Late Indosinian. And the faults＇ development of the upper layer began in the Mid-Late Indosinian, the movement brought overall uplift of the northern basin and the erosion of the top of Leikoupo Formation. In the Yan-Mountain Movement, faults of the upper and lower structural layer has been further developed, which resulting in the piedmont fold belt squeeze deformation strongly. Then, the tectonic framework has been shaped basically. Himalayan Movement has a superimposed and reformed influence on the tectonic in the study area.
出处
《地质科学》
CAS
CSCD
北大核心
2013年第1期71-92,共22页
Chinese Journal of Geology(Scientia Geologica Sinica)
基金
国家自然科学基金项目(编号:40739906)资助
关键词
四川盆地
川北地区
三叠系
地震解释
构造特征
演化分析
Sichuan Basin, Northern region of Sichuan,Triassic, Seismic interpretation, Structure characteristics, Evolution analysis
