东海南部海域高精度重磁场调查

本文对1987及1988两年中在东海南部海域进行的海洋重力,海上磁测及陆地地磁日变观测工作做了系统介绍。共有5个航次,295条测线,站间距25m,剖面总长度达12172km。资料整理结果表明,测量是高精度的,重力测网各交点闭合差的场方差不超过2mgal,地磁则不超过4nT。     

基于细胞神经网络重力异常提取的东海火成岩分布

岩浆活动是东海盆地在形成发展过程中各期构造运动伴生的产物,由于火成岩一般与围岩具有明显密度差异,从而引起局部重力异常,但火成岩引起的异常往往被区域异常所掩盖,在重力异常图上无法识别。利用改进细胞神经网络方法对东海盆地火成岩引起的重力异常进行提取,能够突出目标异常,将水平(横向)叠加异常区分开以识别火成岩。结果表明,东海盆地火成岩发育广泛,以NNE向条带状分布为主。     

两种不同类型大陆边缘的初步研究

１９８６年１０月－１９８７年５月,中国第三次南极考察暨首次环球科学考察的实测重力资料表明,太平洋型活动陆缘重力异常面貌复杂,空间异常变化剧烈,处于极度不均衡状太民。用ｓｉｎｘ／ｘ法反演了 莫氏面深度,利用水层和地壳引起的垂直引力之和与实测的空间异常之差反演了软流层顶界的深度。     

法国“阿塔郎特”号海洋调查船上的重力取样

在海洋地质调查中，如何取得好的沉积物样品是每一位海洋地质学家所向往的，而获得好的沉积物样品的关键又很大程度上取决于先进的海洋调查仪器的使用。法国“阿塔郎特”号海洋调查船上的重力取样管不管在性能上，还是安全性上都瞰称世界上比较先进的取样设备。     

冲绳海槽西部陆坡碎屑沉积物的搬运方式:滑塌和重力流

通过对冲绳海槽2000多公里的实测单道地震资料(95和99航次)和沉积物柱状样(92航次)分析,认为滑塌和重力流是冲绳海槽西部陆坡(东海陆坡)碎屑沉积物向海槽搬运的重要方式;分析结果表明,西部陆坡这两种作用是广泛存在的。陆坡沉积物堆积速率、地形坡度和构造活动、地震、海啸等因素造成了陆坡南、北和中段之间的滑塌和重力流发育程度存在差异。海底滑塌和重力流这两种作用可以同时发生,也可以单独发生,但柱状样揭示重力流发生得更频繁。从空间分布上看,海底滑塌主要分布于上陆坡的断裂带附近,平行海槽呈带状延伸;而重力流沉积主要分布于断裂带向下一直到槽底的部位。重力流沉积主要有4种表现形式：1)沉积物重力蠕动;2)浊积平原;3)透镜状浊积体;4)沿斜坡的碎屑流沉积。上述研究表明,滑塌和重力流不仅是陆架向海槽输送物质的重要方式,也对陆坡沉积结构的塑造起了重要的作用。     

利用重磁震资料解释推断东海海底火成岩

利用1:100万上海幅海洋区域地质调查项目最新获得的重力、磁力和多道地震数据,根据研究区内重、磁场特征,以及已知的火成岩发育状况,在数据处理的基础上,通过剖面和平面相结合,对东海海底的火成岩进行了推断解释,从而得到火成岩在空间上的展布位置。分析认为东海海底火成岩具有沿北北东向成带发育的特点,沿深大断裂侵入于中生代地层;北北西向火成岩带发育时间较晚,规模小,与北西向断裂形成较晚相对应,火成岩分布呈现东西分带的特点,陆架盆地中低部隆起为喜马拉雅早-中期岩浆岩。     

重力式海洋平台的运动响应

本文在分析重力式海洋平台的力学模型基础上，建立了平台运动的拉格朗日方程，并用多尺度法求解平台的运动响应。     

Predicting Bathymetry from the Earth's Gravity Gradient Anomalies

Historically, prediction of ocean floor depth, or bathymetry, has been based on the isostatic modeling and linearized relationships between gravity anomalies and bathymetry. The need for isostatic modeling limits the application of the resulting bathymetry predictions as constraints in geophysical models. An alternative technique making use of the Earth's vertical gravity gradient for predicting bathymetry is explored in this paper. This technique is based on the fact that the observed gravity gradient anomalies result primarily from local mass concentrations on the ocean floor, and that mass compensation by the oceanic crust has an insignificant effect on the gravity gradients, and can be neglected. The resulting bathymetry prediction therefore is independent of isostatic modeling assumptions, allowing it to be used as a constraint on models of lithospheric compensation and for other geodetic and geophysical applications.     

The Role of Multi-Mission ERS Altimetry in the Determination of the Marine Geoid in the Azores

This study concerns the determination of a regional geoid model in the North Atlantic area surrounding the Azores islands by combining multi-mission altimetry from the ERS (European Remote Sensing) satellites and surface gravity data. A high resolution mean sea surface, named AZOMSS99, has been derived using altimeter data from ERS-1 and ERS-2 35-day cycles, spanning a period of about four years, and from ERS-1 geodetic mission. Special attention has been paid to data processing of points around the islands due to land contamination on some of the geophysical corrections. A gravimetric geoid has been computed from all available surface gravity, including land and sea observations acquired during an observation campaign that took place in the Azores in October 1997 in the scope of a European and a Portuguese project. Free air gravity anomalies were derived by altimetric inversion of the mean sea surface heights. These were used to fill the large gaps in the surface gravity and combined solutions were computed using both types of data. The gravimetric and combined solutions have been compared with the mean sea surface and GPS (Global Positioning System)-levelling derived geoid undulations in five islands. It is shown that the inclusion of altimeter data improves geoid accuracy by about one order of magnitude. Combined geoid solutions have been obtained with an accuracy of better than one decimetre.     

东海陆架盆地南部中生界的残留厚度

以最新的地震资料和重力资料为基础,结合钻井数据,采用密度多界面同时反演方法,得到了东海陆架盆地南部中生界顶底界面的埋深,据此编制了中生界残留厚度图。在此基础上,结合构造单元对中生界展布特征进行了分析。结果表明：除在雁荡低凸起构造高点局部缺失外,东海陆架盆地南部中生代地层分布广泛;中生界残留厚度在各个构造单元分布不均,但总体上具有“西北薄东南厚、南北分块”的特征,东部基隆凹陷为整个研究区的沉降中心。