The Yong' an basin developed on the Pre-Devonian basement, locating on the southern margin of the Cathaysian block, distributing along the Zhenghe-Dapu fault zone in NE-SW direction. Making use of the method of sequence stratigraphy and being supplemented by field investigation, writers studied the stratigraphic sequences and rock assemblages of the basin :① An analysis on the stratigraphic framework and geological column from Late Paleozoic to Early Triassic shows that marine deposit sequence is episodic with the fluctuation of sea level, and different sedimentary facies have disproportion in the eastern part, central part and western part of the basin. The center of deposition and subsidence is approximately in the areas of Longyan and Meixian. ② A research on the cross sections traversing the basin and the intrabasinal auxiliary sections shows that the block faulting has played a main part during Meso-Cenozoic, reformed the Late Paleozoic strata and formed compound fault-fold strata. ③ The layers with organic carbon provide the time limits for the land-sea changes in the basin, and their locations and shapes can demonstrate the dynamic mechanism of the tectonic evolution in the basin. Based on analyzing tectonic events, paleogeography and provenances, deep seated structures, boundary structures, and so on, studying the tectonic setting evolution and its stress mechanism, we can get the conclusions as follows; ① During Late Paleozoic, the speed of incursion and regression of the sea was controlled by the strong and weak alternation of tectonic events in different time, for this reason, the ablation of coastal uplifting areas and weathering denudation of mountain mass with the drafting background provided sedimentary source materials for the basin, and there were two provenance areas in the north and south of the basin. During Meso-Cenozoic, the basin had totally the piedmont and river-lake sedimentary facies on volcanic environment. ② The basin is characterized by devoloping uplift-extension structures, and it has mainly undergone phases of Variscan paralic tremendous thick deposition, Indosinian transition from sustained platform to active continental margin accompanied by compressing and uplifting and Meso-Cenzoic tectonic reworking with the conversion from compressing to pulling after Indosinian. The knowledge from above could provide new fundamental referential information for the weak basic research of the basins in southeast China.%永安盆地发育在前泥盆纪基底之上,位于华夏块体南缘,沿NE向政和—大埔断裂带展布.利用层序地层学方法,辅之以野外调查,研究了永安盆地的地层序列和岩石组合:①对晚古生代至早三叠世地层格架及柱状剖面的分析表明,伴随海平面的升降,海相沉积序列具有阶段性,不同沉积相在盆地东、中、西区段分布不均,盆地沉积沉降中心大致位于龙岩和梅县地区；②对横贯盆区的地质剖面及盆内辅助剖面的研究表明,中—新生代,盆内以断块作用为主,改造了晚古生代地层,代之以断褶复合地层；③有机碳质层为盆地的海陆变迁作了时域界定,并且其赋存部位和形态也在空间上表征了盆地构造演化的力学机制.通过分析构造事件、古地理及物源区、深部构造、边界构造等盆地要素,研究了盆地的沉积构造环境演化及其应力机制,结果表明:①晚古生代,海进海退的快慢受控于不同时期构造事件的强弱变化,由此产生的沿岸隆起区的剥蚀以及拉张背景的山体风化剥蚀为盆地提供了物源,存在北、南两个物源区；中—新生代,盆地总体为火山活动背景下的山前及河湖相沉积环境.②盆地具有隆起—伸展构造发育的特点,主要经历了华力西期海陆交互相巨厚沉积阶段,印支期稳定的台地向活动大陆边缘转变阶段并伴随挤压隆升,以及印支期后中—新生代由挤压向拉张机制转换的构造改造阶段.以上认识为中国东南部盆地的薄弱基础研究提供了新的基础参考信息.
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