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1.
西藏阿里札达盆地上新世--早更新世河湖相地层的重新厘定与划分 总被引：7，自引：3，他引：7
通过对札达盆地河湖相地层的野外地质调查和剖面实测，对分布于盆地内的新近系上新统-第四系下更新统地层进行了详细的研究和划分，重新厘定了该区上新世-早更新世岩石地层单元，建立了生物地层和年代地层层序。首次提出了该区上新统-下更新统三分方案，将该套河湖相地层重新划分为第四系下更新统香孜组（Qp^1-1x）、新近系上新统古格组（N2^2g）和上新统托林组（N2^1t）3个组、7个沉积相、11个岩性段，并为确定上新统与下更新统的界线位置提出了具体意见，为青藏高原乃至全球新近系上新统与第四系的研究、划分提供了重要依据。 相似文献
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鱼卡煤田是青海省重要的煤炭资源基地,主要含煤地层为中侏罗统。区内含煤地层角度不整合于奥陶系上统滩间山群之上。根据野外实剖地质剖面岩性特征自下而上划分为侏罗系中统大煤沟组、上统采石岭组、红水沟组。其中大煤沟组分为下含煤段、砂岩段、上含煤段、页岩段;采石岭组分为下部砂岩段、上部砂泥岩段。大煤沟组与以往划分的大煤沟组、石门沟组相当。 相似文献
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<正> 福建境内魏坊地区的奥陶系出露最完整、研究也最详细,1931年王绍文于魏坊之西十余公里的罗峰溪村一带创立“罗峰溪千枚岩”,罗峰溪群一名系指整合于震旦系之上、不整合于晚泥盆世粗碎屑岩之下的一套厚度巨大的浅变质砂、泥、硅质复理石建造。时代统归下古生界。福建省区调队将本套地层划分成四个群五个岩性段,创建东坑口群、魏坊群 相似文献
4.
米仓山基底周缘震旦纪岩石地层及层序地层特征 总被引：4，自引：0，他引：4
本文详细描述了米仓山南缘南江杨坝震旦纪地层剖面,将该区上震旦统划分为观音崖组和灯影组,并首次将灯影组细分为四个岩性段,同时查明了各组段的岩石组合及空间变化规律,根据岩石学,沉积环境及沉积地层界面特征将米仓山周缘地区上震旦统划分为两个沉积层序及一个超层序,分析了各体系域特征及海平面变化规律。 相似文献
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应用钻井、测井、古生物及地震资料,对埕岛地区中生代地层进行了综合研究。结果表明:中生代地层自下而上划分为坊子组、三台组、蒙阴组和西洼组,其中坊子组和三台组细分为上、下两段;受控于断层活动,除埕岛低凸起上缺失中生代地层外,其余地带均发育;坊子组、蒙阴组地层分布较为稳定,厚度变化较小,三台组、西洼组在横向分布不稳定,局部地层缺失;中生代地层接触关系复杂,除发育顶底两个不整合面以外,在三台组与坊子组、蒙阴组与三台组及西洼组与蒙阴组之间至少发育了2个地层不整合。 相似文献
7.
豫皖交界中新生代地层特征及盆地演化 总被引：4，自引：0，他引：4
豫皖交界地段中新生代盆地位于合肥盆地的南缘。该区中新生界划分方案不一。通过超覆不整合的厘定及区域对比将其自下而上划分为中侏罗统三尖铺组、凤凰台组，上侏罗统金刚台组，下白垩统段集组、陈棚组，第三系戚家桥组和第四系。中新生界沉积物以陆相红色类磨拉石建造和陆相火山碎屑岩建造为主，陆相红色类磨拉石的建造分析表明其形成于洪积扇和扇前河湖环境，碎屑来源是沉积区南侧的大别隆起和向北逆冲的浅变质岩带。其盆地类型为复合盆地，具有由南向北、由西向东迁移的特点，而盆地的性质则发生了从前陆盆地向断陷盆地的转变 相似文献
8.
介绍了对东寒武系进行层序地层学研究所采用的方法，层序的基本特征及取得的主要成果。确定有１０个层序，其时限为１－１０Ｍａ，其中下寒统武有６个，中上，上寒武统各２个。此外还划分出次层序２７个，组合层序２个。此项研究工作对本区寒武系地层划分与对比，界线的确定具有重要意义：１．沧浪阶生物地层的争论，是由于滇东存在两个Ⅰ型层序边界，乌龙箐段与红井哨段为假整合关系，故生物带发育不完整；２．双龙潭组与西王庙组应 相似文献
9.
在中生代山东分为鲁东、鲁西、华北平原三个地层分区。鲁西地层分区在不同时期、不同研究者建立和使用了许多不同的岩石地层单位，使用比较混乱。本文对相关的岩石地层单位进行了讨论，提出了新的划分方案。侏罗系建议使用淄博群，划分为中、下侏罗统的坊子组和中、上侏罗统的三台组；白垩系建议使用下白垩统蒙阴组和西洼组；上白垩统固城组。其中固城组的时代根据所产化石由原来归为古新统而改为上白垩统。同时建议，废除“汶南（亚）组”和“分水岭（亚）组”，并且在鲁西地层分区不使用鲁东地层分区的“杨家庄组”、“曲格庄组”、“八亩地组”等岩石地层单位。 相似文献
10.
据岩石地层、气候地层、生物地层和磁性地层等方法综合,将上海疏松地层划分为上第三系和第四系。古地磁测量表明,第四系和上第三系之间的界限位于考克斯年表上高斯正极性期凯纳事件或为英斯事件处。这与河北阳原盆地泥河湾、云南元谋盆地、华北平原东部及长江三角洲可以对比。上第三系为中新统白龙港玄武岩和陆相沉积的上新统崇明组组成。第四系划分为四个“统”,十“个组”。 相似文献
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第四代福建省1：50万地质图对我省侵入岩建立了一套较完整的岩石谱系单位,且可供我省今后在地质工作中使用。本文以1：25万三明幅侵入岩为例,讨论使用福建省岩石谱系单位时所出现的问题,并提出处理意见、同时认为单元仅有较小区域的意义,在全省范围内对比有困难,应以超单元作为岩体对比的基本单位。 相似文献
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We present a compilation of published data(field,petrography,ages and geochemistry)from 73 ophiolitic complexes of the Central Asian Orogenic Belt.The ophiolitic complexes,ranging in age from Neoproterozoic to Triassic.have been geochemically classified as subduction-related and subductionunrelated categories applying recent,well-established discrimination diagrams.The subductionunrelated category is further subdivided into Mid-Ocean Ridge type(MOR),a common rift-drift stage and Plume type,and the subduction-related category is subdivided into Backarc(BA),Forearc(FA).Backarc to Forearc(BA-FA)and Volcanic Arc(VA)types.The four subduction-related types define highly different geochemical features,with the BA and FA types defining end members showing subduction influence of 10%-100%and 90%-100%subduction influence,respectively,and the two other types(BAFA and VA)define values between the two end members.The subduction-related category comprises79%of the examined ophiolites,of which the BA type ophiolites is by far the dominant group,followed by the BA-FA type,and with FA and VA types as subordinate groups.The Neoproterozoic and Ordovician complexes exhibit the highest,whereas those of Silurian age exhibit the lowest subduction-influence.Of the remaining 21%subduction-unrelated ophiolites,the MOR type dominates.Both the subductionrelated and subduction-unrelated types,in particular the latter,are commonly associated with alkaline basalts taken to represent ocean island magmatism.Harzburgite,dunite,gabbro and basalt are the common lithologies in all ophiolite types,whereas the BA-FA,FA and VA types generally contain intermediate to felsic rocks,and in the FA type boninites occur.The subduction-related ophiolites types generally show low metamorphic grade,whereas greenschist.amphibolite and blueschist grades occur in the subduction-unrelated and BA types.The highly different subduction contribution(from 0 to 100%in the MOR and FA,respectively),attest to variable dips of the subducting slab,as well as variable flux of subduction-related elements into the mantle above subducting slabs,from where the ophiolite magmas got their geochemical fingerprints.As most MOR ophiolites get subducted to the deep mantle,the subduction-related ophiolites have become a dominant ophiolitic type on Earth’s surface through all times supporting the idea about the early start of Plate Tectonics. 相似文献
14.
根据区域构造、古地理和地层资料,中国奥陶纪的诸多板块、地体和活动带应分属11个地理区。文章重点研究了各地理区的边界。这些相邻的地理区块在奥陶纪曾处于远距离分离状态,除华北区南界和华南区北界明显由同期秦岭活动带限定之外,地理区的界线大多只能沿发生在奥陶纪之后的构造拼贴结合带划定,只有塔里木区北界和北疆区南界,得以通过追索代表曾在奥陶纪时段内发育于塔里木板块/哈萨克斯坦中间板块/西伯利亚板块之间的局限洋盆或深海盆地遗迹（即残留缝合带）来予以确定。中国大陆的最终形成经历了从晚石炭世至新生代的长期地质演化过程,主要包括活动带的消减以及板块和地体的漂移、增生与会聚。 相似文献
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The Newmarket Till forms a regionally extensive aquitard separating two major aquifer systems in the Greater Toronto area,
Canada. The till is incised, and sometimes eroded entirely, by a network of sand- and gravel-filled channels forming productive
aquifers and, locally, high-conductivity windows between aquifer systems. Leakage through the till may also be substantial
in places. This study investigates the spatial variability of aquitard leakance in order to assess the relative importance
of recharge processes to the lower aquifers. With a large database derived from water-well records and containing both hard
and soft information, the Sequential Indicator Simulation method is used to generate maps of aquitard thickness and window
probability. These can be used for targeting channel aquifers and for identifying potential areas of recharge to the lower
aquifers. Conductivities are modeled from sparse data assuming that their correlation range is much smaller than the grid
spacing. Block-scale leakances are obtained by upscaling nodal values based on simulated conductivity and thickness fields.
Under the "aquifer-flow' assumption, upscaling is performed by arithmetic spatial averaging. Histograms and maps of upscaled
leakances show that heterogeneities associated with aquitard windows have the largest effect on regional groundwater flow
patterns.
Electronic Publication 相似文献
17.
介绍了创新地勘设备管理的手段,提出要强化人员的学习培训,设备维护要科学化,引进条码技术,实行设备的电子化管理和动态管理,强化设备的经济管理。 相似文献
18.
Garth van der Kamp 《Hydrogeology Journal》2001,9(1):5-16
Shallow clay-rich aquitards limit groundwater recharge to underlying aquifers, but they also protect the aquifers from contamination.
The bulk hydraulic conductivity of such shallow aquitards can range from less than 1 mm/year to more than 100 m/year and may
be much greater than the hydraulic conductivity of small intact samples of the aquitard material. This enhanced hydraulic
conductivity diminishes the qualities of the aquitards for the protection of underlying aquifers but allows a higher rate
of recharge. For aquifers that are overlain by aquitards, management and protection of groundwater resources may be critically
dependent on reliable determinations of aquitard permeability.
A variety of methods for determining bulk hydraulic conductivities of shallow clay aquitards is available; each has drawbacks
and advantages, and each is based on simplifying assumptions. These methods include slug tests, pumping tests, response of
the aquitard to mechanical loading, and analysis of natural pore-pressure fluctuations. Several of the commonly used methods
require an independent measurement of specific storage. Laboratory methods for determining specific storage are probably not
representative of in situ conditions and may lead to overestimation of aquitard permeability. Much of the theory developed
to date depends on the assumption that horizontal displacement of the solid material is negligible, and this may not be a
valid assumption for highly deformable media such as clay aquitards. However, with judicious selection of the most suitable
methods for a particular site, good test design, careful instrumentation, and respect for the underlying assumptions, reliable
determinations of aquitard permeability can be obtained.
Electronic Publication 相似文献
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罗田片麻岩杂岩位于大别造山带腹地，东、西大别变质带之间，面积约６０００ｋｍ２。主要由一套花岗片麻岩系组成。它们经历过早期高角闪岩相至麻粒岩相变质和晚期低角闪岩相叠加变质。该杂岩的原始建造以古老变质变形侵入体为主，与其周边构造变质单元的原始建造迥然不同，后者皆为沉积型或火山－沉积型原始建造。罗田片麻岩杂岩与其周边环境的地质特征不一致，是个造山带规模的外来变质地体。其下存在广泛的低密度岩层，相当于混合岩化或花岗岩化的硅铝质岩系。罗田片麻岩杂岩是华南、华北陆块碰撞期间，可能曾经存在的古岛弧深成岩系发生深变质强变形，并在仰冲机制作用下，于 地壳深层次拼贴到高压／超高压碰撞混杂岩之上的，具有推覆体属性的构造岩片。 相似文献
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P. McMahon 《Hydrogeology Journal》2001,9(1):34-43
Several important biogeochemical reactions are known to occur near the interface between aquifer and aquitard sediments.
These reactions include O2 reduction; denitrification; and Fe3+, SO4
2–, and CO2 (methanogenesis) reduction. In some settings, these reactions occur on the aquitard side of the interface as electron acceptors
move from the aquifer into the electron-donor-enriched aquitard. In other settings, these reactions occur on the aquifer side
of the interface as electron donors move from the aquitard into the electron-acceptor-enriched, or microorganism-enriched,
aquifer. Thus, the aquifer/aquitard interface represents a mixing zone capable of supporting greater microbial activity than
either hydrogeologic unit alone. The extent to which biogeochemical reactions proceed in the mixing zone and the width of
the mixing zone depend on several factors, including the abundance and solubility of electron acceptors and donors on either
side of the interface and the rate at which electron acceptors and donors react and move across the interface. Biogeochemical
reactions near the aquifer/aquitard interface can have a substantial influence on the chemistry of water in aquifers and on
the chemistry of sediments near the interface.
Electronic Publication 相似文献