【作者】 沈鹏飞；

【导师】 方念乔；

【作者基本信息】 中国地质大学（北京） ， 海洋地质， 2014， 博士

【摘要】 南雄与丹霞盆地位于南海北缘的大陆基底之上，它们在同一构造体系下与南海海盆经历了彼此之间具有密切联系的地质过程，其主要形成与活动时间，正好处于南海构造转换过程的时间段，在一定程度上可以作为南海演化的“陆基监视器”。本文通过对南雄盆地和丹霞盆地沉积序列、碎屑岩地球化学、碎屑组分以及重矿物组合等特征进行分析和研究，认为盆地底部以岩屑砾岩、杂砂岩和长石砂岩相为代表的磨拉石堆积为主的特征，多显示活动的陆缘弧特征；盆地上部在火山活动时期发生由细到粗变化的沉积组合，显示以二元结构为标志的裂谷环境。通过南雄盆地和丹霞盆地构造环境分析表明，96Ma前后存在一重要的构造环境转换节点，推测是古南海俯冲条件下活动陆缘弧后挤压环境向张裂环境转换的标志，可能与古南海俯冲向现代南海开裂即活动陆缘向被动陆缘的转换无关。通过沉积序列及物源的研究发现，南雄盆地和丹霞盆地构造环境在时间上由弧后前陆环境向裂谷盆地环境转换，在空间上活动中心由丹霞盆地迁移至南雄盆地。另外，裂谷环境的沉积物源与被动陆缘的比较相似，但由于裂谷环境的复杂性以及火山活动的参与，单一使用碎屑岩的化学特征鉴别裂谷环境具有局限性，需要应用综合的方法从总体上对裂谷盆地的构造环境进行探讨。更多还原

【Abstract】 Nanxiong and Danxia basins are located on the continental basement of thenorthern margin of South China Sea. They, together with South China Sea basins,experience geological processes in close contact with each other in the same tectonicsystem. Most of formation and activities time just had happened in the South ChinaSea tectonic transition process. Accordingly, they could be the "land-base monitors"of South China Sea evolution to a certain extent.The characteristics of sedimentary sequences, clastic geochemical, clasticcomponents and heavy mineral combination in Nanxiong and Danxia basins havebeen discussed and researched. The main components of the basin floor is molasseaccumulation, which is represented by cuttings conglomerate, greywacke, feldsparsandstone facies. The components mostly show active continental marginal arcfeatures, while the changes of sedimentary association of the upper basin shows therift environment，which marked by dual structure. Through tectonic environment ofNanxiong and Danxia basins analysis, there exists conversion node of tectonicconditions in about96Ma. It is a sign of extrusion environment of active continentalmarginal arc conversion to rifting environment in the subduction of Pre-South ChinaSea conditions. And it may not be related to conversion of subduction of Pre-SouthChina Sea to the rift of South China Sea, that is, conversion of active continentalmargin to passive continental margin.Through the study of sedimentary sequence and source, the tectonicenvironment of Nanxiong and Danxia basins had converted from foreland basin ofposterior-arc to rift basin in time and activity center migrated from Danxia basin toNanxiong basin in space. The rift sedimentary source material is similar to passivecontinental margin. Because of the complexity of volcano activity participation andpre rift stage tectonic background, the discrimination and analysis of single detritaland chemical composition is limitation in rift stage. Therefore, the tectonicenvironment of rift basin should be studied by composite approach as a whole.更多还原