中国南方含油气区构造-沉积类型及其勘探潜力

南方含油气的复杂构造区根据构造—沉积类型的不同,可将其分为四种类型。通过对不同类型典型含油气区的生烃量及非构造运动天然气散失量的化学动力学计算,认为这四种类型含油气区的油气聚集潜力从好到坏依次为:喜马拉雅运动抬升暴露型、燕山运动抬升暴露型、反复抬升—沉降型和海西—印支运动抬升暴露—后期浅埋型。主要构造运动发生越晚,对油气保存越有利。     

辽北法库变质杂岩的组成、变形与变质特点及构造属性

辽北法库变质杂岩的形成时代、大地构造属性及其与长春-延吉缝合带的形成过程一直以来都是众多地质学者关注的重要科学问题。本文试图通过U-Pb年代学以及物质组成分析、变形变质作用特点分析和区域对比的方法来建立法库变质杂岩的时空格架,大地构造归属及区域构造演化。通过详细的野外工作和镜下分析得到法库变质杂岩存在至少两期变形作用特点及角闪岩相-高绿片岩相至低绿片岩相的变质作用特点。通过对杂岩体中不同类型变质岩的锆石SHRIMP U-Pb年代学研究得到中志留世糜棱岩化黑云母花岗闪长岩原岩年龄为433±3Ma;晚志留世绢云长英质糜棱岩原岩年龄为423±5Ma;早二叠世绢云绿泥方解斜长糜棱岩原岩年龄为292±2Ma;早三叠世长英质糜棱岩原岩年龄为250±3Ma。通过区域对比,笔者认为法库变质杂岩为索伦-西拉木伦缝合带东延的一部分是长春-延吉缝合带的重要组成,其形成演化具有复合型造山的特点,具有复杂的构造演化史。     

文昌B凹陷差异伸展-走滑机制及控藏作用研究

为查明文昌B凹陷油气富集差异性的原因,基于断裂展布和形成期次、构造样式组合、构造演化和断层活动的差异等标志,建立了差异伸展-走滑机制,识别出19洼为伸展-强走滑、14洼为伸展-中等走滑、30洼为伸展-弱走滑。差异伸展-走滑作用控制了优质烃源岩的展布和供烃方向,控制输导体系类型和运移动力,提供物源通道和改造储层,还控制了圈闭类型和力学性质。进一步深化了走滑增压理论,基于先存断裂形态、伸展应力场右旋演化和应变差异,建立了走滑增压圈闭识别方法,识别出S型增压、右行左阶增压、斜交型增压3种走滑增压构造。研究表明,文昌B凹陷的油气富集受伸展-走滑构造背景、源-运时空配置关系所控制,强—中等走滑变形、发育优质中深湖源岩的文昌19洼和14洼是油气富集区。该研究成果成功推动了文昌凹陷近期的多个勘探发现。     

2018年9月8日墨江地震及周边地区构造应力场特征分析

2018年9月8日,云南省墨江县发生MS5.9地震并伴随一系列余震,探究该地震周围的应力场对于理解该地震的发生机制和后续地震的发展趋势具有着重要的参考意义.本研究收集了震源及其邻区中前人研究和Global CMT所给出的震源机制资料,对该地区进行了构造应力场反演,并同时利用反演得到的应力张量模拟墨江地区的震源机制解表现.结果表明:(1)在应力轴整体分布上,自西向东σ₁轴(压轴)从NNE-SSW向逐渐转向NNW-SSE向,σ₃轴(张轴)从WWN-EES向逐渐转向WWS-EEN向,张轴呈弧形分布,压轴呈放射状分布.(2)在应力轴倾伏角上,研究区域内的压应力轴和张应力轴倾伏角都比较小,即两轴均接近水平.(3)R值分布大体是在东南部相较于西北部大,结合当地地质背景分析得到,物质逃逸自西北向东南呈逐渐变缓的趋势.(4)利用反演得到的应力张量和应力状态计算墨江地震震源区的相对剪应力和相对正应力大小.由此推测,墨江地震恰好发生在相对剪切应力值和相对正应力正值最大的节面上.从而可以确定墨江地震的发震节面的基本参数:走向216.32°,倾角86.91°,滑动角...     

郑州市城区深部基岩层热储特征分析

通过对郑州市城区深部基岩层热储的岩性、构造、热源及盖层条件分析研究,总结了该区热储特征,并首次提出了断裂循环型带状热储构造网络体系的构思,这对该区今后深部基岩层热储的研究具有一定的参考意义。     

Two belts of HTLP sub-regional metamorphism in the New England Orogen,eastern Australia: occurrence and characteristics exemplified by the Wongwibinda Metamorphic Complex

Abstract

Two north–south-trending belts of high-temperature–low-pressure (HTLP) sub-regional metamorphism have been identified in the New England Orogen of eastern Australia. Metamorphic complexes in the ～1300?km long Early-Permian Inland belt have ages ca 300–290?Ma, and those of the ～400?km long Mid-Permian Coastal belt ca 275–270?Ma. These periods correspond to the beginning and end of an extended (early–mid Permian) phase of subduction rollback and crustal thinning in eastern Australia. This paper describes and incorporates recent work on the Wongwibinda Metamorphic Complex in the southern New England Orogen as a basis for comparison with thirteen other HTLP sub-regional occurrences within the orogen. These are described in as much detail as is currently available. Some outcrops of HTLP rocks in difficult terrain have been subject to limited study and only conditional comparisons can be made. However, a significant number of characteristics shared between the complexes including: their location at the higher-temperature end of broad areas of very low-grade to greenschist facies metamorphic rocks, indicative of tilted crustal blocks; their association with major shear zones; the presence of migmatite at the high-temperature end of a steep metamorphic field gradient; the presence of two-mica granite formed by the melting of the local sedimentary pile; and temporal association with S-type granites; imply a common extension-related mechanism of formation for these HTLP belts. The connection with major faults and shear zones suggests the belts trace major crustal-scale extensional structures that migrated eastwards from ca 300 to 270?Ma.

1. KEY POINTS

2. Two previously undocumented belts of HTLP subregional metamorphism are identified within the NEO.

3. Available dating indicates that metamorphism occurred along the belts at the beginning and end of a major early–mid Permian extensional phase in eastern Gondwana/Australia.

4. The characteristics of the HTLP complexes including their association with shear zones indicates they may delineate major loci of extension.

     

南秦岭东段冷水河向斜构造解析

在系统测量褶皱、断层、节理、线理、擦痕等构造形迹位移参数的基础上,通过构造解析方法,获得了该区自古生代以来的四期构造应力场。四期应力场的方向及性质分别为:(1)以264°～290°方向挤压为主,辅以335°～15°方向拉伸的伸展期;(2)以360°～15°方向挤压为主的压缩期;(3)以50°～60°方向挤压为主的压缩期;(4)以340°～10°方向位伸为主,后辅以284°～295°方向位伸的伸展期。研究表明,四期构造应力场的特征与构造演化的表现是基本一致的。     

德雷克海峡的扩张历史及其影响

本文利用首次南大洋考察期间获得的德雷克海峡地球物理场资料,解释海峡海底板块扩张历史以及海峡扩张对南极环境形成的影响.     

东秦岭松树沟蛇绿岩的形成环境探讨

东秦岭松树沟蛇绿岩是秦岭造山带中出露于变质基底岩系之上的、形成于中元古代晚期（１０００～１２５０Ｍａ）的异地蛇绿岩构造岩片，与周围变质地层里构造接触关系，为一自南而北的逆冲推覆岩片，于９８３Ｍａ±发生构造侵位及变质作用。蛇绿岩主要由超镁铁岩和镁铁岩两个单元组成，变质橄榄岩（纯橄榄岩、方辉橄榄岩）具地幔残余成因，ΣＲＥＥ低，ＲＥＥ特征为ＬＲＥＥ富集、ＨＲＥＥ近平坦型式。变质基性火山岩的常量元素、微量元素和稀土元素地球化学特征显示以Ｔ－ＭＯＲＢ为主，兼具有ＯＩＢ特征，形成于小洋盆构造环境，于晋宁期北秦岭活动大陆边缘的俯冲－碰撞过程中发生变形变质并侵位于陆壳当中。     

Provenance, diagenesis, tectonic setting and geochemistry of Tawil Sandstone (Lower Devonian) in Central Saudi Arabia

The Tawil Sandstone (Lower Devonian) in Central Saudi Arabia overlies the Sharwara Member of the Tayyarat Formation (Silurian) and succeeded conformly by the Shaiba Member of the Jauf Formation. Petrographical data reveal that the Tawil Sandstone comprises 96% quartz, 3% feldspar, and 1% rock fragments and all samples are classified as quartz arenites. The presence of well sorted, altered to fresh feldspar, and discriminate function analysis suggests that the sediments have been subjected to substartial reworking resulting in a high level of maturity. Modal analysis data (Q–F–L) suggest a stable cratonic provenance for the sediments and accumulation in a passive margin basin is indicated (binary plot of SiO₂ vs K₂O/Na₂O). Diagenetic features include dissolution of feldspar and rock fragments, compaction, reduction of the existing pore space through rearrangements, and rotation and fragmentation of grains resulting in dissolution of quartz grains and cementation.