江南古陆变质基底地层年代的修正和武陵运动构造意义

江南古陆变质基底的研究中,最突出的基础地质问题依然是地层年代的精确标定。地层年代标定涉及到成矿地层的划分和对比及其构造演化的时限,也直接影响层控矿床找矿中涉及的基础地质问题。在最新的中国地层年表中,前寒武纪地层对比和构造背景解释已发生重大变化。本文依据扬子块体和华夏块体新元古代地层中最新的系列锆石U—Pb测年结果,初步揭示“江南古陆”变质基底地层火山事件和分布范围。结合全球格林威尔造山运动基本特征,对江南古陆变质基底地层年代的修正将有利于重新厘定江南造山带的成矿背景,提供层控矿床基础年代地层资料,为新的矿产资源大调查服务。     

江南古陆东段两类玄武岩成因的地球化学制约

在江南古陆东段,广泛发育晚元古代的玄武岩,据岩相学和地球化学特征可区分为明显不同的两类:低钛玄武岩和高钛玄武岩.它们由上地幔的不同程度部分熔融产生的岩浆结晶形成.     

姬塬地区延长组长2油层地层的精细划分与对比

地层的精细划分与对比是油气勘探研究的基础工作,地层划分的好坏直接影响着油气勘探后续的研究。在收集大量的地质资料基础上,以鄂尔多斯盆地姬塬油田主要生油层——延长组长2油层组为研究目的,在全区内寻找分布比较稳定的主要标志层K9和长2底砂岩以及K7辅助标志层,将延长组长2油层组地层划分为3个小层。本研究为该地区的开发提供可靠的依据,并为下一步大规模开发建产作好了技术储备。     

河南灵宝盆地中新生代陆相地层的新划分与对比研究

灵宝盆地位于华北板块南缘与秦岭造山带之间,是豫西北一系列北东-南西向断陷盆地之一.盆地内沉积地层主体为一套厚约2000m陆相碎屑岩夹泥灰岩、薄煤层沉积.本文根据盆地内的恐龙蛋、介形虫、腹足类、哺乳动物化石及少量孢粉等,将地层自下而上划分为下白垩统枣窳组、上白垩统南朝组、古近系古新统-下始新统项城群、中始新统川口组、上始新统庄里坡组及新近系上-中新世（组名暂未定）等6个地层单元.研究表明：下、上白垩统之间及其与项城群之间为不整合或超覆,上中新统与川口组或庄里坡组为不整合接触,整个地层是一套河流相沉积、局部洪泛洼地或小浅湖相沉积.     

泥河湾组的时代、地层划分和对比问题

通过泥河湾盆地大道坡和洞沟两个剖面的古地磁和古气候学研究,对泥河湾组的时代和地层划分提出了新的认识.泥河湾组Ⅰ ,顶底分别距今约2.48Ma和3.40Ma,属上新世,可与黄土高原的红粘土层对比;泥河湾组Ⅱ段,距今2.48～0.97Ma,可与午城黄土对比;泥河弯组Ⅲ段,距今0.97～0.13 Ma,大致可与离石黄土对比.根据上述地层划分方案,建立了泥河湾组地层框架,并进而与其他剖面做了对比分析.     

浙江温州北部地区白垩系地层划分与对比

本文根据温州北部地区的火山一沉积岩地层的剖面,进行了岩石地层、生物地层、年代地层的综合研究和区域对比,针对以往1：25万、1：20万和1：5万区域地质调查的划分和归属提出了新的看法。浙东南下白垩统火山一沉积岩分为上、下两个岩系,下岩系称磨石山群,上岩系称永康群。研究认为,温州北部地区的火山-沉积岩系主体为下白垩统下岩系的磨石山群,并非均为上岩系的永康群馆头组;在永嘉枫林、澄田一带的火山-沉积岩地层分别属于磨石山群大爽组和茶湾组,而桥下一带的沉积岩地层则属于永康群馆头组。     

沈阳市城区第四纪地层的划分

根据第四纪地层所构成的地貌单元、地层的成因类型、岩性组份及其层次，采用区域地层对比方法。划分了沈阳市城区的第四纪地层。结果表明，这一地区的第四地层具有岩性均一、分布连续等特点，地层厚度变化大致在10-80m的范围内。     

福州盆地埋藏晚第四纪沉积地层划分

文中以14个钻孔地层编录为基础,结合前人研究资料,初步总结了福州盆地埋藏第四纪地层的沉积特征。福州盆地沉积始于晚更新世中期(约56.5ka BP),由砾石、砂、黏土、淤泥组成,总体表现为从下至上粒度变细的沉积序列,地层岩性横向变化较大;盆地内发育3层淤泥,第1,2层淤泥发育于全新世中晚期,时代为1.44～7.86ka BP,为“长乐海侵”的产物,第3层淤泥发育于晚更新世晚期,时代约为44～20ka BP,为“福州海侵”的产物;盆地埋藏晚第四纪地层可划分为上更新统和全新统,分为4个组,从老至新分别为龙海组(Q3pl)、东山组(Qhd)、长乐组(Qhc)与江田组(Qhj)。龙海组归属上更新统,划分为3段,其余3个组归属全新统     

华北中元古代燕山盆地生物群演化及其与地质事件的耦合关系

对华北中、新元古代燕山盆地发育的三个主要阶段的生物群面貌进行了总结,三个阶段分别为:长城系下部碎屑岩沉积阶段(A),长城系上部至蓟县系碳酸盐岩沉积阶段(B),蓟县系上部至青白口系碎屑岩沉积阶段(C).其中阶段B是本研究的重点研究层位.B阶段的页岩相化石虽然不甚丰富,但燧石相生物化石却有着较高的分异度和丰度,并具有多种类型的形态及纹饰.此外B阶段中缺乏大直径个体.阶段B的生物群丰度、分异度、浮游生物和底栖生物分异度比例、底栖球状化石平均直径、球形化石最大直径在时间尺度上具有明显的变化规律.笔者从中识别出了两个典型的生物群演变事件,两个事件都和地质事件相耦合.事件一发生于大红峪组三段,这一时期生物群中大个体浮游生物化石十分繁盛,推测可能与火山活动有关.事件二发生于高于庄组三段,这一时期的生物群发生了整体面貌的更替,该更替事件与叠层石衰减、海洋元素地球化学指标以及碳同位素等多个因素的变化耦合.     

江西弋阳铁砂街中元古代海底火山喷流成矿作用

江西弋阳铁砂街铜矿产于中元古代晚期海相火山岩中,矿床在大地构造环境、含矿地层建造、矿体形态、喷流岩组合、喷流岩主量－微量－稀土元素地球化学、同位素地球化学方面都具有海底火山喷流沉积的典型特征,是扬子板块、华夏板块边缘中元古代裂谷海底火山喷流沉积作用的产物。     

Geochemical constraints on the petrogenesis of basalts from eastern Jiangnan orogen, South China

The basalts crop out widely in the eastern part of late Proterozoic Jiangnan orogen. In terms of their petrographical and geochemical characteristics, they can be divided into two distinct types: low- and high-Ti. basalts. They crystallized from the magmas derived from the depleted upper mantle differing in partial melting degree. Project supported by the National Natural Science Foundation of China.     

Sedimentary environment and development controls of the hydrocarbon source beds:Middle and Upper Proterozoic in northern North China

Problem on development control of marine source bed hold in Chinese petroleum industry progression. The Hongshuizhuang Formation,Tieling Formation and Xiamaling Formation in the Middle and Upper Proterozoic are important hydrocarbon source beds in northern North China, and investigation of their sedimentary environments and the controls has great significance for petroleum exploration in North China. Based on sedimentology (sequence stratigraphy), palaeoecology, sedimentary geochemistry, and sedimentary palaeogeography, their development pattern is discussed. All these studies indicate that the development controls of the hydrocarbon source beds include a favorite palaeogeographic location, exceeding propagation of biomes in low and middle latitudes, anoxic environments, enrichment of phosphorus element and the adsorption of clay minerals during the preservation of organic matter in the marine carbonates.     

地震横波勘探及其在浅层岩土分层中的应用

简单论述了横波的基本特点,指出在松散层勘探中,横波勘探的优势主要在于探测精度高且不受饱水度的影响.因此,可以选择地震横波勘探进行第四纪松散层层序划分及厚度探测.并以广州市城市地质调查项目为例,介绍了地震横波勘探在浅层地层勘测中的数据采集方法,分析了地质解释依据,并结合波速测井方法对地层层面进行了划分.分析结果表明了多数岩土层与反射界面有较好的对应关系,用地震横波勘探结合波速测井进行第四纪松散层层序划分及厚度探测是可行的.     

江南造山带南段电性结构特征及地学意义研究

华南板块是中国大陆的重要组成部分,普遍认为其由华夏和扬子地块沿江南造山带拼合而成,之后又经历了多期次的构造、岩浆活动.对华南板块的形成与演化研究一直是热点问题.本文采用一条始于扬子地块内部并南东向穿越江南造山带南段、华夏地块的大地电磁测深剖面,经过数据处理与分析,反演与模型验证等工作后,获得了可靠的岩石圈二维电阻率模型,并对江南造山带南段的边界、扬子地块和华夏地块与江南造山带的接触关系等重要问题进行了讨论.电阻率模型显示扬子地块、江南造山带南段和华夏地块之间电阻率差异明显,其中华夏地块岩石圈整体表现为大范围的高阻,扬子地块由浅至深表现为高-低-高阻的层状结构,而两者之间的江南造山带南段深部表现为明显的低阻.根据电阻率模型的特征,得出如下主要结论：江南造山带南段西界为开远-平塘断裂,东界为萍乡-茶陵断裂;江南造山带南段深部的大范围低阻区域是二叠纪沉积岩的电性反映;华夏地块下方南东向倾斜低阻区解释为早三叠纪右江盆地持续下沉导致江南造山带俯冲到华夏地块之下的电性反映.

     

Geochemistry and tectonic implications of Proterozoic amphibolites in the northeastern part of the Yeongnam massif, South Korea

Abstract   Amphibolites in the Haenggongni area (Haenggongni amphibolite) and the Okbang area (Okbang amphibolite) in northeastern Yeongnam massif, South Korea occur as a sill-like body or inclusions within the metasedimentary sequences of the Proterozoic Wonnam Group. Major and trace element characteristics demonstrate that both amphibolites have tholeiitic chemical affinity. They are characterized by nearly flat rare earth element (REE) patterns, and low contents of immobile incompatible elements and have low values of Zr/Y, Ti/Y, La/Nb and Ta/Yb ratios, indicating enriched (E)-type mid-oceanic ridge basalt (MORB) affinities for their protoliths. This suggests that amphibolite protoliths formed in an extensional rift setting leading up to ocean opening. In combination with the previous studies in Yeongnam massif, three protolith types of amphibolites are assumed (E-type MORB, within-plate basalt and volcanic arc basalt). They could have been originated in different tectonic settings and/or different episodes. These characteristics are clearly different from the amphibolites in the Gyeonggi massif and Okcheon belt, in which most of the amphibolites show a within-plate basalt affinity that developed in continental rift zone.     

时频分析在地层旋回性分析中的应用

时频分析技术是一项十分有效和直观的地震资料特殊解释技术,它通过一定的处理方法,把时间域的数据转换为频率域时频数据,时频分析在地质勘探中具有广泛的应用,表现在地层旋回性方面,它可以实现对不同类型沉积旋回的研究、层序界面的追踪和对比以及不同规模沉积旋回的研究。     

Turbidity dynamics in karstic systems. Example of Ribaa and Bittit springs in the Middle Atlas (Morocco)

Abstract

The identification of the turbidity mechanisms in two karstic springs (Ribaa and Bittit) located in the Middle Atlas Plateau in Morocco was performed by means of correlation and spectral analyses applied to time series of rainfall, flow rates, and turbidity. Time series analyses of rainfall and discharges revealed high inertia and storage capacities of the karstic systems. However, the occurrence of turbidity in the springs proved independent of discharges. A causal relationship between rainfall and the occurrence of turbidity in the form of waves was established. Accordingly, turbidity was assumed to be related to the hydrodynamic conditions prevailing in the karst. Turbulent quickflows in the karst transmissive conduits, following heavy rainfall, are thought to provoke the resuspension of solid particles deposited in the conduits, as well as their transport towards outlets. An external origin has also been contemplated, concerning infiltration waters may be loaded with suspended matters washed from the watershed.     

Application of radiolarians and other fossils in non-Smith strata

The main character of melange strata in an orogenic belt is the integration of mixed materials due to the superposition, displacement or loss of various tectonic slices (blocks) of different origins and environments, different scales, different grades of deformation and metamorphism, and different stages of tectonic evolution. The approach to non-Smith strata in an orogenic belt is to focus on the understanding of the age, facies, tectonic setting of the original formation and the process of deformation-metamorphism of each tectonic slice, reconstruct the history of dispersal and integration of these tectonic slices in time and space, i.e. 4-dimensional. This paper studies the age and facies of the original formation of tectonic slices in the A’nyêmaqên melange belt based on new data of radiolarians, sporo-pollen and trace fossils, and cast new lights on the research of the evolution process of that belt.