关于“海陆对比”研究的若干实践和思考  

Practice and Thinking on the Study of“Sea-Land Correlation”

作　　者：方念乔[1] FANG Nianqiao(School of Ocean Sciences,China University of Geosciences,Beijing 100083,China)

机构地区：[1]中国地质大学(北京)海洋学院,北京100083

出　　处：《现代地质》2022年第1期1-13,共13页Geoscience

基　　金：国家自然科学基金项目(41276047,41572207)。

摘　　要：通过剖析和总结两个重要的研究经历和学术成果:(1)应用东北印度洋的深海钻心研究喜马拉雅山—青藏高原隆升,(2)应用南海周边陆域的岩浆-沉积记录研究"古南海"的消亡和南海的早期开裂,作者阐释了对于这一特殊的"海陆对比"研究的理解、策划与心得体会。在前一项凭海观山的研究中,首先明确在东北印度洋区存在两类组分、成因各不相同的深海沉积序列,它们分别坐落于孟加拉海底扇和东经90°海岭,在响应山脉隆升的方式上各具优势。经过对两个序列的替代性指标的严格筛选与对比,确定3.6~3.2 Ma和1.0~0.6 Ma是晚中新世以来山脉与高原隆升影响最为深刻的关键时段。在第二项由陆识海的研究中,须要处理的则是较第一项更为复杂的包括岩浆、构造、沉积甚至陆上钻井在内的地质记录,而且其保存条件远逊深海沉积系列。此类研究的优势在于,可以避免单一钻孔记录的局限性,助力研究者在更广阔的区域内综合各种适用的基础材料,构建反映海陆一体化的区域构造演化框架。在华南大陆边缘,存在中生代晚期活动陆缘向新生代被动陆缘的重大构造转换。为建立一个完整的陆缘弧体系,作者于研究区布设了"十字形"考察路线,在东西向追索最初发现于海南的陆缘弧的展布特征,在南北向查明陆缘弧的结构样式,发现在白垩纪中期(110~80 Ma)发生强烈的因板块汇聚而产生的区域隆升,且由南向北隆升强度减弱。经过与同期浙闽陆缘岩浆-沉积记录的综合对比,认为中生代向北俯冲的"古南海"很可能属于业已消亡的特提斯域。中生代末华南陆缘进入全新的发展阶段,三水盆地因展现白垩纪—始新世规模最大且保存最好的岩浆-沉积过程被选为被动陆缘破裂研究的中心地区。古新世晚期(~57 Ma)以碱性玄武岩-粗面岩-钠闪碱流岩为代表的碱性系列双峰式火山喷发活动在研�In this paper the author shares his two important scientific experiences and results on“Sea-Land Correlation”:(1)to research the Himalayan and Tibetan uplift based on data from the NE Indian Ocean,and(2)to research the closure of the“proto-South China Sea(SCS)”and the birth of the SCS based on magmatic-sedimentary records from their neighboring landmasses.The unique sea-land correlation provides an effective access on the understanding of regional evolution.In the first study of monitoring the mountain uplift based on marine deposits,two highly-distinct(in composition and origin)deep-sea sedimentary sequences are discriminated.Located on the Bengal submarine fan and Ninetyeast Ridge,respectively,each sequence has its own respond signals to the Himalayan and Tibetan uplift.By strictly sieving and correlating the proxies from those sequences,this study argues that the most important periods of the uplift of the Himalayan Mountain and Tibetan Plateau occurred since Late Miocene,at 3.6-3.2 Ma and 1.0-0.6 Ma.In the second study of approaching the seas from the continental materials,highly complicated records including magma,structure,sedimentation and logging,whose preserved condition is usually inferior to those records collected from the deep sea,need to be dealt with.The advantage of such study is that researchers are permitted to organize multidisciplinary materials in a large region,and set up the regional evolutionary framework based on land-sea integration,thereby avoiding limitations brought by a single submarine drilling hole.In the southern margin of China continent there was a subversive change from the Late Mesozoic active pattern to Cenozoic passive pattern.To reconstruct systematically a Mesozoic marginal arc,the author established a cross-shaped investigation approach:searching for the extension of arc discovered in Hainan Island in the E-W direction and finding out the arc architecture in the N-S direction.It is found that a drastic regional uplift resulting from the plate convergence occurred

关 键 词：东北印度洋 喜马拉雅—青藏高原隆升 华南陆缘 南海 海陆对比 

分 类 号：P736.1[天文地球—海洋地质] P56[天文地球—海洋科学]