古陆、古隆与古地理

Old land,old uplift and palaeogeography

地质历史中有两种性质不同的陆源区:一是格林威尔期或更早期的构造事件,导致陆块拼合、固结、基底克拉通化,在边缘形成古老剥蚀区,称之为古陆;二是震旦纪至显生宙期间,由于洋陆转换、盆山转换构造事件,原沉积盆地反转成隆起,形成新的物源区,称之为隆起,可分为克拉通边缘隆起和克拉通内隆起。克拉通内隆起具穿时性,制约下伏盆地沉积物进积和上覆晚古生代海侵上超边界。穿时的界面在三维空间上即是沉积和层控矿床的储集空间,也是油气成藏的关键因素之一。而克拉通边缘隆起则具有构造障壁的作用。

There are two distinct terrigenous areas in the geological records.One is the old lands which were formed by landmass matching,consolidation and basement cratonization in Grenville orogeny or even earlier.For instance,the North China landmass was consolidated during the Luliang movement,and the Tarim and Yangtze landmasses were consolidated during the Sibao-Jinning movement.The differences of time durations for the landmass consolidation may exercise a major control on the Early Palaeozoic sedimentary basins.The other is old uplifts which resulted from the inversion of the pre-existing sedimentary basins caused by the ocean-continent transition and basin-range transition during the Sinian to the Phanerozoic.The uplifts can be divided into two types： the pericratonic uplift and intracratonic uplift.The intracratonic uplifts are diachronous,and may exercise the controls on the progradation of the underlying sedimentary terrains,the boundary and distribution of the overlying Late Palaeozoic marine basins,and sea-level fluctuation and tectonic subsidence,resulting in the formation of several sequence unconformities.These uplifts may provide valid spaces for sedimentary and/or stratabound ore deposits,and for hydrocarbon accumulation.The pericratonic uplifts tend to act as the tectonic barriers.