南大西洋中段被动陆缘阿普特盐岩研究进展  

Progress in the study of the Aptian salt basins in the passive continental margin of the central South Atlantic

作　　者：李海滨 陈全红 毕素萍[2] 陈杰 LI Haibin;CHEN Quanhong;BI Suping;CHEN Jie(CNOOC International Ltd.,Beijing 100028,China;PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China)

机构地区：[1]中国海洋石油国际有限公司,北京100028 [2]中国石油勘探开发研究院,北京100083

出　　处：《海洋地质前沿》2025年第1期1-10,共10页Marine Geology Frontiers

基　　金：中海油“十四五”重大科技项目“两岸一带重点区油气勘探评价关键技术”(KJGG2022-0902)。

摘　　要：南大西洋两岸被动陆缘盆地在早白垩世阿普特期沉积了一套分布广泛的蒸发岩,其成分和成因不仅对研究南大西洋的形成和演化具有重要意义,也是油气勘探关注的重点。通过综合分析近年来有关盐岩的分布、时代、成因和构造沉积背景等研究进展,总结目前存在的主要争议,指出分歧的原因和解决的方法:(1)盐岩厚度大,变形复杂,两侧宽度和对称性变化与盆地的伸展模式及板块破裂的位置有关;(2)生物地层和同位素定年表明,盐岩在各盆地的沉积下限约为118~116 Ma,上限为115~110 Ma,阿普特阶生物层型不完善和同位素年代数据太少是造成其差异的主要原因,化学地层学精细对比为确定其时代提供了新的方法;(3)盐盆北部较南部更富含易溶成分,相对于海水源自南部大洋和蛇纹石化脱水两种模式,源自北部大洋的热液卤水模式更能解释其成分差异,且与古生物、古地理及古气候证据相吻合;(4)基于对洋陆边界、不整合成因和盆地沉降机制认识的差异,对盐岩沉积于大洋形成前、形成后或是形成过程中仍存在不同观点,明确盐下基底的性质是解决这一问题的关键;(5)需要结合古气候、古地理综合分析盐岩沉积于浅水深盆还是浅水浅盆环境,而且随着蒸发作用的进行,盐盆水平面并非一直保持不变。A set of widespread evaporates was deposited in the conjugate basins in the passive continental mar-gin of the central South Atlantic during the early Cretaceous Aptian Stage,and the composition of the evaporates and the origin of the basins are important for the study of the southern Atlantic Ocean evolution and hydrocarbon exploration.We reviewed the recent progresses in the study of the distribution,age,origin,tectonic and sediment-ary settings of the evaporates,summarized the main disputes that exist today,and pointed out the reasons of the disagreements and the resolutions.Results show that①the thick evaporates were deformed strongly and vari-ations in width and symmetry are related to the pattern of basin extension and location of the plate breakup.②Biostratigraphy and isotopic dating indicate the salt deposition started at 118-116 Ma and ended at 115-110 Ma,and the differences are caused by incomplete Aptian international framework and scarce radiometric data,which could be solved by precise correlation of chemostratigraphy.③The northern part of the salt basin is richer in soluble components than the southern part.Compared with the two models of seawater that originated from the southern ocean and from serpentinization dehydration,the hydrothermal brine model in which seawater is origin-ated from the northern ocean can better explain its compositional differences and is consistent with paleontologic-al,paleogeographic and paleoclimate materials.④Based on the differences in understanding of ocean-continent boundaries,the origin of unconformities,and the mechanism of basin subsidence,there are different views on whether the evaporates were deposited before,after,or during the rifting.Clarifying the nature of the subsalt base-ment is the key to solving this problem.⑤It is necessary to comprehensively analyze whether the salt rock was deposited in a shallow water deep basin or a shallow water shallow basin environment based on paleoclimate and paleogeography.Moreover,as evaporation proceeds,the level

关 键 词：阿普特盐盆 盐岩时代 成分差异 盐岩成因 构造沉积背景 

分 类 号：A736[哲学宗教—马克思主义哲学] P313[天文地球—固体地球物理学]