新疆博格达山北缘二叠纪中—晚期构造运动的沉积响应     

鲁智帅  谢庆宾  张津宁  祁利祺  许涛  陈佳  相泓含 《地质论评》2024,70(1):102-122

博格达山北缘是准噶尔盆地与天山造山带之间的关键部位,是研究盆山关系的重点区域。博格达山北缘二叠纪中、晚期的构造演化与沉积时空演变关系存在较大争议。本研究通过野外实地勘测、镜下岩石薄片鉴定、粒度分析实验和地震资料解析等方法,针对博格达山北缘东、西部两条剖面—大龙口剖面和井井子沟剖面开展研究,分析其沉积类型和演变过程,解析盆山构造变形和发育特征,探讨构造运动的沉积响应。研究结果表明：瓜德鲁普统乌拉泊组为湖成三角洲相,井井子沟组至红雁池组为湖泊相,乐平统泉子街组为冲积扇—河流相沉积,梧桐沟组和锅底坑组为滨浅湖—三角洲相沉积;研究区可分为两个主要构造层,下构造层以伸展断陷为主要结构,上构造层以前陆冲断为主要构造变形;多期构造活动控制瓜德鲁普统、乐平统沉积演化过程,在挤压构造背景下,瓜德鲁普统的湖泊相转变为乐平统冲积扇—河流相沉积,晚期构造活动趋于稳定,区域进入准平原化作用阶段。  相似文献   

南祁连清水沟一带奥陶纪盐池湾组岩石地层特征     

张国英 《西北地质》2004,37(1):6-12

在南祁连清水沟一带,盐池湾组呈北西西-南东东向展布．为一套深灰绿色细碎屑浊积岩系夹深海泥岩。主要岩性有变泥质粉砂岩、长石石英杂砂岩、细砂质长石石英粉砂岩、长石杂砂岩、绢云石英千枚岩等。岩石中粒序层理、交错层理不太发育,指示该组岩层层序是倒转的．即北老南新。该组发育不完整鲍玛层序,有3种类型．即ABCD型、韵律型和均一型。综合研究盐池湾组的宏观岩性特征、基本层序、沉积构造、浊流沉积岩石学特征、粒度曲线特征、微量元素、稀土元素指数等蕴藏在沉积岩中的各种地质信息,指示该组形成于次深海至深海相浊流沉积中端相和远端相区。浊积岩与深海泥岩以不同比例重复组合,构成复理石沉积建造。  相似文献   

The Cretaceous sedimentary history of the Pindos Basin (Greece)     

Peter?NeumannEmail author  Wolfgang?Zacher 《International Journal of Earth Sciences》2004,93(1):119-131

The Cretaceous sedimentary rocks of the Pindos Zone in western Greece document the evolution of a Tethyan deep-water basin. New sedimentological and micropalaeontological studies reveal a complex basin history. Siliceous sediments with abundant radiolaria and organic-rich facies prevailed up to the early Late Cretaceous. Within the sediment-starved pre-Middle Cenomanian, marked black shale levels appear that are probably linked to oceanic anoxic events. At the change from the late Early to the early Middle Cenomanian, the sedimentary regime altered abruptly. The early Late Cretaceous is characterized by major calcareous redepositional events (orbitoline horizons) and often associated siliciclastic turbidite deposition (submarine-fan environments). In the late Late Cretaceous, carbonate supply increased rapidly, resulting in the evolution of a carbonate slope and basin-plain setting. Pelagic and allodapic limestones recorded basinwide blooms in planktonic foraminifera (elevata event) and a polyphase redepositional history that is interpreted to reflect the sensitivity of the basin to the tectonic evolution of Apulia.  相似文献   

Retention of Precambrian Rb/Sr phlogopite ages through Caledonian eclogite facies metamorphism, Bergen Arc Complex, W-Norway   总被引：1，自引：0，他引：1  

A. Kühn  J. Glodny  K. Iden  H. Austrheim 《Lithos》2000,51(4):423-330

The Lindås Nappe, Caledonides W-Norway was affected by two major tectonometamorphic events. A Precambrian granulite facies event at T=800–900°C, P<10 kbar was followed by localized Caledonian eclogite facies (T=650–700°C and P>15 kbar) and localized amphibolite facies reworking. During the granulite–eclogite facies transition, anorthositic rocks were converted from garnet granulites to kyanite eclogites, while phlogopite-bearing spinel lherzolite reacted to garnet lherzolite. The eclogite and amphibolite facies reequilibration took place along shear zones and fluid pathways. In the unhydrated and undeformed parts, the minerals preserved their granulite facies composition with constant Fe/Mg ratios from core to rim, suggesting diffusional reequilibration. Rb/Sr age dating was carried out on relict granulite facies minerals from three lenses of ultramafites (Alvfjellet, Hundskjeften and Kvamsfjellet). Phlogopite from phlogopite lherzolite at Alvfjellet give 857±9 Ma, while clinopyroxene, amphibole, phlogopite and whole rock from a lherzolite at Hundskjeften yield an age of 842±12 Ma (MSWD=1.9). Clinopyroxene, feldspar, orthopyroxene phlogopite and whole rock from websterite, Kvamsfjellet, yield an age of 835±7 Ma (MSWD<1), while clinopyroxene, phlogopite and whole rock from a lherzolite from the same lens gives a result of 882±9 Ma. These results are interpreted as minimum ages for the granulite facies event and only slightly younger than, or overlap with previous U–Pb zircon ages (929±1 Ma) and Sm–Nd garnet–pyroxene ages (890–923 Ma) interpreted to date the end of the granulite facies event. By contrast, ages obtained for the eclogite and amphibolite facies range from 460 (U–Pb, sphene), 440 (Ar–Ar), 419 (U–Pb, zircon) to 410 Ma (Rb/Sr mineral ages).

These results demonstrate that the reopening temperature for the Rb/Sr system in phlogopite–biotite under dry and static high-pressure conditions is, in the given mineral assemblages, at least 650°C, considerably higher than the 300–400°C assumed as the closure temperature of this system. We ascribe this elevated reopening temperature to fluid absent conditions that prevented element transport and rehomogenization.  相似文献   

Evolution of a post-batholith dike swarm in central coastal Queensland, Australia: arc-front to backarc?   总被引：8，自引：0，他引：8  

Charlotte M. Allen 《Lithos》2000,51(4):331-349

A swarm of felsic and mafic dikes cuts a Late Carboniferous–Permian batholith called the Urannah Suite in central coastal Queensland. Late Permian–Triassic westward thrusting (Hunter–Bowen Orogeny) exposed this mid-crustal Suite and the crosscutting dikes, thus enabling examination of dikes that range in age from syn- to post-batholithic. Although both mafic and felsic dikes have the same dominant northerly strike, field, geochronologic and geochemical examination reveal that the swarm is composite; felsic dikes are older (285 Ma) and geochemically and isotopically distinct from mafic dikes (273–229 Ma). Dike compositions are compared to those of the host plutonic rocks, and to volcanic rocks the same age as the dikes. Whereas the felsic (older) dikes are compositionally similar to their host granites (initial ⁸⁷Sr/⁸⁶Sr>0.7045), the mafic (younger) dikes are isotopically (Sr, Nd, Pb) less radiogenic. Moreover, several different types of mafic dikes are evident based on geochemistry; most of these have mixed characteristics in terms of tectonic classification. All but two dikes of basalt and basaltic andesite composition classify as ‘with-in plate' on Ti–Zr–Y tectonic classification plots. Many of the basalts have high TiO₂ contents (1.5–3.0 wt.%). Most of these have REE and spider diagram patterns like calc-alkaline tholeiites, the exceptions being a few alkali basalts recognized by their alkali content, and high Ti, Ce, Nb and Zr contents. When put into the context of all plutonic rocks in the area (late Paleozoic and Mesozoic), these dikes record a transition at 280 Ma, after which time, all magmatism in the region is less isotopically evolved (initial ⁸⁷Sr/⁸⁶Sr=0.7033–0.7044). A model of slab retreat and hinge movement to the east in the latest Permian explains the change of geochemical signature from arc-front to backarc at about 280 Ma.  相似文献   

三维参照变形及应变相研究评述   总被引：2，自引：0，他引：2  

王新社  郑亚东 《地质科技情报》2000,19(4):1-6

三维参照变形和应变相是最近构造地质学领域中取得的重要进展,三维参照变形是理想化的三维变形分类,每一参照变形是共轴级分（拉伸、压扁或纯剪）和与其垂直的简单切组分同时作用的产物,三种可能的面理取向和三种可能的线理取向的不同组合构成六咱应变相,三维参照变形和应变相研究证明糜陵面理未必平行剪切带,可与剪切带斜交,甚至垂直,线理未必与剪切方向一致,可与剪切方向斜交,甚至垂直,出现横向面理时,剪切指向标志位于该面理内,出现横向线理时,剪切指向出现在与线理垂直的ａｃ面理内,三维变形分析不公可解决三维分析难以解释的横向面理和线理,而且可确定共轴组分的类型及其与单剪组分的结合方式。  相似文献   

Application of radiolarians and other fossils in non-Smith strata     

Kexin Zhang  Jichun Huang  Hongfu Yin  Guocan Wang  Yongbiao Wang  Qinglai Feng  jun Tian 《中国科学D辑(英文版)》2000,43(4):364-374

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.  相似文献   

河北省平原地区水资源利用的边际效益分析   总被引：9，自引：0，他引：9  

王智勇  王劲峰  于静洁  刘昌明 《地理学报》2000,55(3):318-328

从经济学的角度给出了利用统计资料计算工农业用水边际效益的方法。并以保定地区为例 ,详细阐述实际运算过程中的数据处理、转换等方法 ,计算出河北省 7个平原地区的工农业用水边际效益值 ,并讨论边际效益在水资源分配中确定合理供水量的作用  相似文献   

准噶尔盆地东北缘中-下侏罗统层序地层与油气   总被引：3，自引：3，他引：0       下载免费PDF全文

方国庆  李育慈  刘德良 《地质科学》2000,35(4):414-421

通过对边缘露头、钻井和地震等资料的综合层序地层分析,划分出下八道湾、上八道湾、三工河和西山窑等4个层序以及湖退体系域(RST)、湖进体系域(TST)、高位体系域(HST)和冲积体系域(AST)等四种类型的9个体系域.层序形成主要受控于构造作用和湖水进退.RST中形成区域上广布的工业煤层;TST中的粗粒退积型辫状三角洲沉积体系中发育很好的储层.快速湖进形成的TST与构造长期稳定形成的HST反复叠置构成良好的生储盖组合.  相似文献   

苏北地区陆相中生界地层问题探讨     

姚柏平  张建球  郭念发 《江苏地质》2000,24(3):140-143

长期以来苏北地工陆相中生界地层问题突出,表现在对钻井地层划分对比上观点很不统一,对地层发育与分布的认识模糊不清。通过地层古生物、钻井地层划分对比研究,结合多方面最新资料和成果,对象山群的分布范围、葛村组的发育与分布、“黑浦口”的归属等问题,提出了新观点。  相似文献