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通过露头实测、踏勘、取样、薄片分析取得扬子地台北缘寒武系露头的基础资料,详细分析露头沉积相并消化吸收前人资料的基础上,对扬子地台北缘岩相古地理特征、控制因素及油气勘探意义进行综合研究.扬子地台北缘受断裂的控制,发育两套地层系统,即扬子地台区地层系统和盆地区(古秦岭洋)地层系统.浅水地台区发育滨岸、浅海陆棚、碳酸盐岩局限台地、碳酸盐岩开阔台地、浅滩、云坪、泥坪等沉积相类型,斜坡区发育垮塌沉积岩相,盆地可以分为页岩盆地、硅质岩盆地、碳酸盐岩盆地类型.扬子地台北缘岩相古地理特征受构造及海平面升降综合控制.板块运动提供了扬子地台北缘类似于被动大陆边缘的古地貌;持续断裂活动导致的斜坡区同沉积作用使得研究区斜坡沉积厚度巨大,并且地台区、斜坡区、盆地区的古地理位置基本保持不变;深大断裂提供的硅质热流体为深海盆地层状硅质岩提供物质来源.海平面主要控制了地台区岩相古地理特征.早寒武世梅树村期发生海侵,研究区整体被淹没,广泛发育碳酸盐岩台地,末期海水退去;筇竹寺期发生寒武纪最大规模海侵,发育大量暗色泥岩;沧浪铺期,古陆上升,海水变浅,发育大量的碎屑沉积物,此时期以沉积碎屑沉积物为主;龙王庙期海平面进一步降低,古陆隆升的幅度变小,提供的碎屑沉积物减少,大面积发育碳酸盐岩;中寒武世又发生海侵,发育碳酸盐岩;晚寒武世发生海退,斜坡区演化成陡斜坡,地台区沉积加速.浅水地台区岩石类型主要有砾岩、砂岩、颗粒灰岩、白云岩等储集岩类型,盆地区发育厚层暗色页岩、硅质岩、碳酸盐岩等可以作为烃源岩的岩石类型.在空间上储集岩和烃源岩具有很好的配置关系,故研究区具有很好的油气勘探前景.
The basic data of Cambrian outcrops in the northern margin of Yangtze platform are obtained through field survey, reconnaissance, sampling and slice analysis. Based on the detailed analysis of outcrop sedimentary facies and the digestion and absorption of previous data, the lithofacies palaeogeographical features in the northern margin of Yangtze platform are controlled Factors and exploration significance of oil and gas.According to the fracture control in the northern margin of Yangtze platform, two stratigraphic systems are developed, namely the stratigraphic system of the Yangtze platform area and the system of the basin area (ancient Qinling ocean) Shallow sea shelf, carbonate restricted platform, carbonate open platform, shoal, cloud floor, mud floor and other sedimentary facies, and the slope area develops collapsed sedimentary lithofacies. The basins can be divided into shale basins, silicalite basins, Carbonate basins.The lithofacies palaeogeographical features in the northern margin of the Yangtze platform are controlled synthetically by the structure and sea level rise and fall.The plate movement provides the paleogeomorphology similar to the passive continental margin to the northern margin of the Yangtze platform, Sedimentary effect makes the thickness of slopes in the study area huge, and the paleogeographic positions in the platform area, slope area and basin area remain basically unchanged; Geothermal fluids provide the material source for stratiform chert in the deep basin.The sea level mainly controls the lithofacies palaeogeographical features in the platform area.At the Precambrian plum age, transgression occurs and the study area is submerged as a whole and carbonate is widely developed Rock platform, the end of seawater receded; Qiongzhu period Cambrian occurrence of the largest sea transgression, the development of a large number of dark mudstone; Canglang shop, the ancient land rose, sea water shallow, the development of large amounts of detrital sediments, this period to sediment The sediments of the clastic sediments are dominant; the sea level of the Longwangmiao Period further decreases; the extent of the uplift of the Proterozoic in the Palaeozoic becomes smaller and the sedimentary supplies provided are reduced; carbonate rocks are developed over a large area; transgression occurs during the Middle Cambrian and carbonate Salt rocks, late retreat in the Late Cambrian, steep slopes evolving into steep slopes and sedimentary facies accelerated in the platform area.The rock types in the shallow platform include mainly conglomerate, sandstone, particulate limestone and dolomite, In the area, thick-bedded dark shale, silicalite and carbonate rock can be used as the rock type of source rock, and there is a good relationship between reservoir rock and source rock in space, so the study area has good Oil and gas exploration prospects.