Structural geology and tectonics in marine science: Perspectives in the research of deep sea and deep interior

The fields of structural geology and tectonics have witnessed great progress over the last decade and are poised for further expansion in the future. One of the significant breakthroughs is the establishment of the ’Beyond Plate Tectonics Theory’ where a combination of conceptual models and numerical modeling on plume tectonics and plate tectonics has enabled new insights into the structural and tectonic architecture and processes in the deep interior and deep sea. This paper synthesizes developments of structural geology and tectonics from a macroscopic perspective in deep interior and deep sea. Four key techniques are also reviewed: satellite altimetry for surface structures in deep-sea multi-beam sea-floor mapping; tomography for tectonics of the deep interior; diverse modeling approaches and software for unfolding dynamic evolution; and techniques for HT/HP experiments on material rheology and in situ component measurements.     

The tectonics beneath the Okinawa Trough

The nature of the crust of the Okinawa Trough is different from that of the continental shelf in the East China Sea. The crust beneath the Trough is in transformation from continental to oceanic and the depth of MOHO in the northern section of the Trough is deeper than in the southern section. Thick sedimentary strata of Neogene and Pleistocene ages are deposited in the Okinawa Trough, and divided into three layers: the upper horizontal layer, the middle layer lightly folded and the lower deformed layer. They were formed in Pleistocene, Pliocene, and Miocene to Paleogene, respectively. The tectonic movement in the southern section is stronger than that in the northern section. Some volcanic seamounts appear on the bottom of the Trough. On both slopes of the Trough are developed many normal faults and the intrusive igneous rocks. The Okinawa Trough, the back-arc basin, is an embryonic marginal basin in rifting and spreading. The formation of the Okinawa Trough started in the early Pliocene. The transformation of crust and the growth of the Trough progressed from the southern to the northern section. The southern section is a true trough in tectonic sense. Contribution No. 986 from the Institute of Oceanology, Academia Sinica. The paper was presented in the PS-11 of IAPSO Symposium, 18th General Assembly IUGG, Hamburg, 22 August 1983.     

Determination of Antarctic geoid by using global gravity field

With Chinese latest global gravity field model WDM94, the authors providethe geoid height and mean free-air gravity anomaly of Antarctica (The range of latitude is from—60° to—90°). In order to conclude and analyze the characters of Antarctic geoid roundly, the authors collect the latest oversea global gravity field model OSU91 (to degree and order 360) and JGMOSU (to degree and order 360), get the corresponding geoid height and mean free-air gravity anomaly. The results arecompared with the results got from WDM94, thus we get the difference. The standard deviation of geoid height between WDM94 and OSU91 is ± 1.90 re;the deviation of geoid between WDM9 and JGMOSU is ± 2.09 m. The standard deviation of mean gravity anomaly are±8.97 mGal and ± 9.32 mGal respectively.     

重力异常数据处理系统的开发与研究

利用SQL Server建立后台数据库和以面向对象的Delphi语言作为应用程序开发工具，在Windows 2000平台上开发了图形用户界面的重力异常数据处理系统。该系统集重力异常数据处理和数据库管理为一体，包括了数据输入、数据处理、数据查询、数据输出、数据库管理和系统安全管理六大功能模块。系统提供简洁的操作界面和友好的应用环境，便于用户使用。在实例运用中，将西藏地区的重力异常数据用该系统进行了处理。结果表明，系统操作简单方便．不仅能提高处理效率，还能实现对数据的系统管理。     

Application of several potential field separation methods of gravity data in Vientiane of Laos area

Gravity data observed in geophysical surveys are the sum of potential field produced by all underground inhomogeneous geological sources with different scales, different patterns and different depths.The aim of gravity exploration is mainly to extract the meaningful local anomaly from the regional gravity anomaly which is helpful to detect the deep structure and delineate the favorable area for mineral prospecting.In this paper, several anomaly separation methods are theoretically discussed, including trend analysis method, finite element method, interpolating cut method and analytic continuation method.And, these methods are applied to achieve the delineation of potash-mine deposit in Vientiane.Through experiments, analysis and comparison, the separating result of upward continuation is shown to be satisfactory, for that can separate the ore body anomaly from the background field more effectively.Further, with the combination of the geological information and gravity anomaly, it infers four rich potash zones in the study area of Vientiane which is significant for future geological work.     

3D Joint inversion of gravity and gravity tensor data

The processing and interpretation of gravity and gradient data plays an important role in geophysics. The cross gradient joint inversion is usually used for achieving structure coupling of multiple geophysical mod-els.In order to realize the coupling of gravity and gravity tensor data, the authors analyzed each component. The results show that different types of data contain different direction information, and derived the joint inver-sion based on cross gradient function and applied it to model data.The theoretical model results show that the cross gradient method can reduce the multi solution and significantly improve the resolution of the inversion. The method was also applied to inverse the gravity tensor data in Vinton salt dome, showing that this method can get higher resolution results than the separate linear inversion, and be closer to the real density from drilling data.     

Active tectonics and erosional unloading at the eastern margin of the Tibetan Plateau

Introduction The eastern margin of the Tibetan Plateau, adjacent to the Sichuan Basin (Figure 1), has become a testing ground for a variety of models that contrast mechanisms of extrusion and crustal thickening associated with the India-Asia collision (Avouac and Tapponnier 1993, England and Houseman 1986),but that also address the extent to which the upper crust and upper mantle are coupled (Royden et al. 1997, Holt 2000). The margin is characterized by topographic relief of over 5 km an…     

Elastic-plastic analysis for pile-anchor supporting system of deep foundation pit

By using numerical analysis methods to simulate the deep excavation, a lot of analyses are established on the basis of two-dimensional plane strain, ignoring the fact that foundation pit possesses three dimensions. For soil constitutive relation, people always take linear and nonlinear model, without considering the plastic behavior of soil. Using plastic-elastic hardening model to simulate constitutive relation of soil characteristics, the authors carried out mechanical analysis for pit excavation and support. The results show that the analysis for the stress state of pile anchor system is an effective way which provides theoretical basis for calculation of soil displacement.     

Elastic-plastic analysis for pile-anchor supporting system of deep foundation pit

By using numerical analysis methods to simulate the deep excavation, a lot of analyses are established on the basis of two-dimensional plane strain, ignoring the fact that foundation pit possesses three dimensions. For soil constitutive relation, people always take linear and nonlinear model, without considering the plastic behavior of soil. Using plastic-elastic hardening model to simulate constitutive relation of soil characteristics, the authors carried out mechanical analysis for pit excavation and support. The results show that the analysis for the stress state of pile anchor system is an effective way which provides theoretical basis for calculation of soil displacement.     

青海省锡铁山铅锌矿成矿元素物质场结构及深部找矿潜力

青海省柴达木盆地北缘锡铁山铅锌矿是我国大型的喷流沉积型(SEDEX)矿床，赋矿围岩主要是大理岩和片岩，浅部主要为大理岩型矿体，深部主要为片岩型矿体。系统描述了不同矿石类型中铅锌矿体与黄铁矿的空间共生关系、矿体空间形态三维变化规律；利用局部奇异性分析方法、相关性分析方法对矿区Pb、Zn、Ag、Au等成矿元素物质场结构特征及变化趋势进行了系统分析，2种分析方法均可表现元素物质场不同的结构特征，即:Pb、Zn、Au元素整体上沿着矿体的侧伏方向仍然有明显的向深部富集的趋势，且不受大理岩的影响，在片岩中物质场所反映的元素富集程度依然很强；Ag元素整体上从浅部到深部在矿化空间内均有明显的不连续富集特征。锡铁山铅锌矿水平方向上元素分带由远至近(由西向东)依次为Mn-Fe-S-Ag-Pb-Zn-S-Au，垂向上元素分带由上到下依次为Mn-S-Ag-Pb-Zn-S-Au，同时系统研究了成矿元素物质场中元素富集结构的变化规律，分析讨论了锡铁山深部找矿潜力。      

Seismic stratigraphy of the Qiongdongnan deep sea channel system,northwest South China Sea

Based on more than 4000 km 2D seismic data and seismic stratigraphic analysis, we discussed the extent and formation mechanism of the Qiongdongnan deep sea channel. The Qiongdongnan deep sea channel is a large incised channel which extends from the east boundary of the Yinggehai Basin, through the whole Qiongdongnan and the Xisha trough, and terminates in the western part of the northwest subbasin of South China Sea. It is more than 570 km long and 4–8 km wide. The chaotic (or continuous) middle (or high) a...     

海塔盆地中部断陷带反转构造特征及其对油气的控制

为研究海塔盆地中部断陷带反转构造的类型、分布、形成机制、与油气藏的关系及成藏模式和控藏特征,分析地震、油气藏开发及地球化学等资料.结果表明:伊敏组晚期,海塔盆地中部断陷带在近东西向压扭应力场作用下发生大规模反转,形成断层型、褶皱型和混合型3类5个亚类反转构造,并与上部含油气系统的大二段次生油气藏具有良好耦合关系.大二段次生油气藏为反转期原生油气藏沿主干反转断裂向上调整形成,以南一中段及下段烃源岩形成的原生油气藏为源,以大二段砂岩为储层,以伊敏组泥岩为盖层,以主反转断层为疏导为成藏模式;该次生油气藏的形成与反转程度密切相关,主要形成于反转程度较弱的塔南凹陷隐伏断展型反转构造发育的区域,北北东向的隐伏断展型反转构造圈闭是寻找该类次生油气藏的首选目标.     

雄安新区高阳地热田东北部深部古潜山聚热机制

为查明雄安新区深部碳酸盐岩热储的赋存特征与聚热机制,中国地质调查局近两年组织实施的雄安新区地热清洁能源调查评价工作,综合地温场背景、深部地质结构、凹凸相间构造格局、深浅断裂系统控热导热、地球物理场特征、区域水动力场、水化学场与温度场的多场耦合指示等综合探测手段,分析总结了高阳地热田东北部深部古潜山地热资源的最新勘查成果,阐述了雄安新区深部高温古潜山热田的聚热机制:①受太平洋板块向西俯冲影响,华北克拉通东部破坏明显,岩石圈、地壳厚度大嵋减薄,有利于幔源热向浅部的传导;②区域马西断层等深大走滑断裂切穿了岩石圈,有利于深部的幔源热物质和深部岩浆上侵入地壳;③热流由低热导率的凹陷区向高热导率的凸起区聚集,地下水沿断裂的深循环对流加热,区域岩溶地下水的汇流区等也有一定的聚热效应。在雄安新区深部碳酸盐岩热储聚热机制理论指导下,在高阳地热田东北部古潜山布设施工了两眼高温、高产地热井,井口水温分别达到109.2℃,123.4℃,揭示验证了雄安新区深部存在地热开发的第二空间——蓟县系碳酸盐岩热储,深部碳酸盐岩地热水温度高、流量大、开发潜力巨大。研究成果对雄安新区乃至华北盆地高温、高产地热井位的布设与深部碳酸盐岩热储开发利用的科学部署具有很好的示范与指导意义。      

南海北部莺-琼盆地典型重力流沉积特征与物源体系

简述了莺-琼盆地横向沉积分布、纵向沉积序列、动态沉积过程,以及浅海重力流的沉积特征与形成机制。南海北部莺歌海盆地黄流组发育了浅海背景下的大型重力流沉积,琼东南盆地发育了半深海沉积环境下的陵水组、三亚组、梅山组海底扇。其中浅海重力流沉积的主要特征体现在：(1)沉积规模大小不等,且展布形态存在较大差异;(2)海平面变化造成沉积特征的复杂性和多变性;(3)浅海重力流沉积通常不具备扇体亚相分异;(4)浅海重力流的水道沉积砂体迁移快、堆积厚,表现为水道富集且多期次叠加。莺-琼盆地物源演化与对比揭示了源-汇过程及不同物源输入的动态时空变化,主控因素包括物源供给、相对海平面变化、差异沉降、古地貌(古坡折及坡度)等。     

Numerical simulation of seepage flow field in groundwater source heat pump system and its influence on temperature field

Energy utilization in the aquifers is a new technology closely related to development of heat pump technique. It is significant for the flow distribution to be predicted in the aquifer surrounding the Groundwater Source Heat Pump System （GSHPS）. The authors presented a new concept of ＂flow transfixion＂ by analyzing general features of aquifers, and then discussed interaction of the flow transfixion with the beat transfixion, which has practical significance to projects. A numerical model of groundwater flow was established based on the basic tenets of water-heat transferring in the aquifer. On this basis the flow field and the temperature field of GSHPS for a site in Shenyang City were numerically simulated. The basis of the flow transfixion was obtained; it was discussed for the influence of the flow transfixion on the heat transfixion. To a certain extent, the study offers some reference for the projects＇ design of GSHP in the studied area.     

Numerical simulation of seepage flow field in groundwater source heat pump system and its influence on temperature field

Energy utilization in the aquifers is a new technology closely related to development of heat pump technique. It is significant for the flow distribution to be predicted in the aquifer surrounding the Groundwater Source Heat Pump System (GSHPS). The authors presented a new concept of "flow transfixion" by analyzing general features of aquifers, and then discussed interaction of the flow transfixion with the heat transfixion, which has practical significance to projects. A numerical model of groundwater flow was established based on the basic tenets of water-heat transferring in the aquifer. On this basis the flow field and the temperature field of GSHPS for a site in Shenyang City were numerically simulated. The basis of the flow transfixion was obtained; it was discussed for the influence of the flow transfixion on the heat transfixion. To a certain extent, the study offers some reference for the projects' design of GSHP in the studied area.     

A preliminary study on the tectonics and evolution of the Fujian Coast Changle—Nanao metamorphism zone

The Fujian coast Changle—Nanao metamorphism zone rocks are composed of gneiss, schist and hornblendite which had gone through metamorphism of amphilbolite facies, and followed the large-scale intrusive mass of gneissic granite. The zone was originally composed of Early Palaeozoic continental margin and island arc volcanic and sedimentary rocks. In 180-150 Ma, the zone underwent ductile shear deformation and amphibolite facies metamorphism; and in 130-80 Ma, rose rapidly and collided with the Southeastern China continental margin volcanic rocks along the NE trending ductile shear belt. The above geologic setting laid the present Fujian coast tectonic foundation whose formation and evolution are known to be interrelated with the subduction and collision of the Taiwan. Central Range. Contribution No. 2589 from the Institute of Oceanology, Chinese Academy of Sciences. The project was supported by NSFC (No. 49472148).     

鄂尔多斯盆地南部彬长区块延长组长6-长7段深水重力流沉积特征分析

鄂尔多斯盆地南部彬长区块的延长组长6-长7段发育厚层无沉积构造的块状砂岩,具有良好的油气显示和开发效益,然而关于该套砂岩的形成机制尚不清晰。确定长6-长7段砂岩的沉积相及沉积模式,对于该套低渗砂岩储层"甜点"形成机制的理解,"甜点"分布模式的预测,以及后续勘探开发都具有重要的指导意义。对彬长区块36口取心井的长6-长7段1 024 m长的岩心进行了沉积学特征描述,结合粒度分析资料及地质制图分析,确定了该套厚层砂岩的沉积相及沉积模式。结果表明:鄂尔多斯盆地南部彬长区块的延长组长6-长7段砂岩共发育15种岩相和3种主要沉积微相类型,即:砂质碎屑流、浊积岩和震积滑塌岩微相,以及它们在空间上的3类组合关系。其深水重力流沉积模式可以概括为扇根（坡折带斜坡上半部分）的震积滑塌相-砂质碎屑流亚相（沉积组合）、扇中（斜坡中下部位-坡脚）的砂质碎屑流-浊积岩沉积亚相（沉积组合）和扇端（坡脚-盆底）浊积砂等亚相（沉积组合）。通过对彬长区块延长组长6-长7段发育的致密砂岩沉积特征的分析与讨论,确定了该厚层块状砂岩的主要沉积相及沉积微相的特征及分布,为致密砂岩储层的高效开发及"甜点"预测提供了科学依据与良好借鉴。      

The effect of sloping bottom topography on the source-driven deep tropical circulation

ImODUCTIONInasedrinalseriesofPapersduringthelatel95osandl96()s,StonimlandANns(l958;l96()a,b)PresentedatheoreticalpictUreofthesoaree-drivendeepcirculaionintheoceanbasedongeOst-cd~cs.ItconsistsofaPole-wAninteriorflowresultingforavortexshetchingassociatedwithaslowuniformuPwellingthInllghouttheocean,andawestemboUndeqctirrentbalancingthemassbudget.Kawse(1987)formulatedalinear,tWo-layerbaxlinicmodeltostud}thedeeptroPicalcirculationdrivenbydeepwaterproduction.DistinctlydifferentfromtheStomm…     

Uncertainty analysis of gravity data inversion

The traditional gravity modelling methods fail to deal with ambiguity zones.These zones are likely to be associated with uncertain boundaries.Source boundaries can be divided into "hard" and "soft" types."Hard" boundary stands for distinguished margin of discontinuity of source distributions.Traditional modelling method is based on this type of boundary.Uncertain boundaries of ambiguity zones belong to"soft" boundary. The authors put forward the uncertainty analysis because lots of uncertainty factors need to be taken into consid-eration.Any powerful system designed to interpret gravity data for a real source distribution must be able to deal with uncertain information.Uncertainty analysis ( UA) is a useful tool to estimate the ambiguity of the data in-terpretation.It is often applied in conjunction with a specific modelling or inversion method.In this study, we use an iterative inversion and its results are evaluated using uncertainty analysis and proved to be effective.