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1.
初论胶北隆起地壳伸展作用 总被引：7，自引：0，他引：7
晚元古宙，胶北隆起在造山运动后期开始发生ＮＷ（Ｗ）→ＳＥ（Ｅ）方向的地壳伸展作用，突出表现于前寒武纪结晶基底内部，持续时间很长久（自晚元宙开始，断续到中生代印支－燕山期），具有改造期伸展作用特点，区域构造处于十分散化的状态，导致褶皱变形及大规模花岗质岩浆侵位。 相似文献
2.
燕山及邻区中新生代挤压与伸展的转换和成矿作用 总被引：7，自引：2，他引：7
通过燕山及邻区中新生代区域性不整合界面、断裂演化、盆地演化、变质核杂岩和岩浆活动等地质事实论述了燕山及邻区中新生代挤压与伸展的转换过程及其与区域成矿作用的关系。认为燕山及邻区中新生代的构造演化过程是在前中生代华北克拉通岩石圈基础上发育起来的克拉通内（陆内）成盆沉积与挤压变形的交替演化过程，在这一构造演化过程中，存在中三叠世末（老虎沟组或杏石口组前，峰值年龄≥215Ma)、早侏罗世末（海房沟组或九龙山组前，峰值年龄≥178Ma)、晚侏罗世末（义县组或东岭台组前，峰值年龄≥135Ma）、白垩纪末（古近系前，峰值年龄65Ma)、古近纪末（新近系前，峰值年龄25Ma)5个挤压作用时期。5个挤压期在时间上相对较短，期间为早中三叠世、晚三叠世－早侏罗世、中晚侏罗世、白垩纪、古近纪、新近纪至第四纪6个时间较长，相对和缓或伸展的成盆沉积期一一隔开。在时间上，主成矿期与强烈伸展期相对应；在空间上外生矿产受伸展地所控制，内生矿产的分布受盆地间隆起带控制。总体上，挤压作用由强变弱，伸展作用由弱变强。伸展作用持续的时间长，挤压作用持续时间相对较短。挤压作用和伸展作用交替出现，挤压机构和伸展构造间互发育，成矿作用与挤压和伸展的转换存在着密切的成生联系。 相似文献
3.
燕山地区燕山期的挤压与伸展作用 总被引：16，自引：2，他引：16
燕山地区中生代断裂演化、区域性不整合界面和盆地演化的地质事实显示，燕山期不仅存在强烈的挤压作用，而且存在强烈的伸展作用。如果把整个侏罗、白垩纪期间的构造运动理解为燕山运动的话，那么燕山运动既形成强烈褶皱和逆冲推覆，又形成断陷地和为质核杂岩。整个燕山运动（旋回）包括3次挤压事件和3个伸展阶段，即早侏罗世末挤压事件（北票组沉积之后，海房沟组沉积之前）、晚株罗世末挤压事件（土城子组沉积之后，义县组沉积之前）和白垩末挤压事件（第三系沉积之前）；早侏罗世盆地伸展阶段、中晚侏罗世盆地伸展阶段和白垩纪盆地伸展阶段。燕山期内发生了3次由伸展到挤压的转换。 相似文献
4.
云开地区构造演化的岩石组构特征 总被引：2，自引：0，他引：2
在综合研究测试云开地区岩石组构的基础上，初步划分出云开地区至少有５期变形组构；晋宁期的组构表现为深层次ＮＮＥ（Ｎ）－ＳＳＷ（Ｓ）近水平伸展体制下的流变剪切滑脱，并发生区域变质和混合岩化；加里东期的组构表现为ＮＮＥ（Ｎ）－ＳＳＷ（Ｓ）挤压体制下的流变剪切，并在滑脱带形成大量同构造重熔型花岗岩；海西－印支期的组构反映了ＮＮＷ→ＳＳＥ的挤压逆冲推覆；燕山早期的组构反映了ＮＮＷ－ＳＥＥ挤压应力场作用了的专 相似文献
5.
华北地台北缘中晚元古代地壳运动分为燕辽旋回（１８～８．５亿ａ）、满家滩旋回（８．５～６亿ａ）。燕辽旋回为本区中、晚元古代坳拉谷发生发展消亡阶段，即地台第一盖层沉积地槽中晚元古代洋壳形成阶段。此阶段的白云鄂博亚旋回（１８～１４亿ａ）伸展裂陷作用为坳拉谷发生发展期，形成长城系；什那干亚旋回伸展拗陷作用为坳担谷发展萎缩期，形成蓟县系；汛河亚旋回收缩拗折作用为坳拉谷萎缩消亡期，沉积青白口系。地台北缘为被动大陆边缘。满家滩旋回地槽区向地台俯冲作用使地台第一次抬升隆起遭受剥蚀，仅在局部坳陷沉积震旦系、地台北部边缘为活动大陆边缘。 相似文献
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关于太古宙—元古宙界线的新认识 总被引：6，自引：1，他引：6
２５００Ｍａ作为太古宙－元古宙界线的提议被２８届国际地质大会通过，但并不意味着２５００Ｍａ作为太古宙－元古宙界线是永恒的最佳选择。事实上，太古宙－元古宙界线划在何处还存在很多争论，现行的界线划分依据也期分期标准相悖。大量资料表明），２３００Ｍａ时曾发生全球地质环境的灾变，灾变前后的地质作用（尤其是表生地质作用），有明显变化，导致了太古宙与元古宙的一系列差别。该灾变与元古宙－显生宙，古生代－中生代， 相似文献
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阴山超大型硫化物矿床形成的有利条件 总被引：1，自引：0，他引：1
阴山中元古代成矿带（狼山 渣尔泰山）属于华北地台元古宙巨大成矿带的西段，产有多处硫铁 多金属矿床，一些已经达到超大型矿床的规模。它们形成的时代和地质环境具显著的热水沉积成矿的特征，可与世界中元古代ＳＥＤＥＸ对比。已经判别出成矿盆地及热水通道等。充足的物质来源、巨大的热源、热水系统演化的完整性、成矿盆地极好的封闭性保证了同生期成矿的高强度，造山期的后生作用也有明显叠加 改造作用 相似文献
9.
云开地块的构造演化史及其动力学特征 总被引：8，自引：0，他引：8
云开地块构造演化史可筛分为６个构造期：（１）前晋宁期（〉１４００×１０＾ａ），发生ＮＥ向超深层次的伸展型顺层滑脱，滑脱带下部发展为区域深熔混合岩和溶熔花岗岩；（２）晋宁期（１４００×１０＾６～８００×１０＾６ａ）发生ＮＮＥ向深层次伸展剪切，剪切带下部逐渐形成条带状深熔混合岩和片麻状深熔花岗岩；（３）加里东期（８００×１０＾６～３７０×１０＾６ａ）发生Ｓ→Ｎ中深层次推覆剪切，剪切带形成高侵位片麻状深 相似文献
10.
碰撞造山作用期后伸展体制下的成矿作用——以小秦岭金矿集中区为例 总被引：3，自引：0，他引：3
小秦岭在中生代期间经历了强烈的构造活动变迁，区域构造体制由挤压向伸展过渡，并最终在伸展体制下于晚燕山期形成小秦岭变质核杂岩，其深部过程为中国东部大陆岩石圈拆沉作用而引起软流圈物质上涌。小秦岭是中国重要的金矿集中区，主要产出3种类型的金矿床，其空间分布规律和成矿时代特征表明，本区金的成矿作用奏始于碰撞造山作用的后期，主成矿期发生在造山作用期后以伸展体制为主导的晚燕山期。碰撞造山带在造山作用期后常常发育伸展构造，伸展体制下的变形变质演化和多源流体活动使大规模成矿作用成为可能。 相似文献
11.
根据国内外发现的地洼区及其与铀成矿时代的关系,分为早元古代、中元古代、晚元古代、早古生代、晚古生代,中生代和新生代等7个不同时代的地洼区。铀的成矿富集,发生在地洼阶段激烈期向余动期的过渡时间内。元古代地洼区地壳固结早,铀成矿年龄值大,地洼余动期时间长。中新生代地洼区地壳固结晚,铀成矿年龄值小,地洼余动期时间较短。 相似文献
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《Gondwana Research》2014,25(3-4):886-901
The Late Mesoproterozoic (1085–1040 Ma) Ngaanyatjarra Rift, previously referred to as the Giles Event, is the dominant component of the Warakurna Large Igneous Province (LIP) that affected much of central and western Australia. This rift is well preserved and provides excellent examples of rift structure at a variety of crustal levels and times in the rift's evolution. Geological knowledge is integrated with geophysical interpretations and models to understand the crustal structure and evolution of this rift. Two phases are identified: an early rift stage (1085–1074 Ma) that is characterised by voluminous magmatism within the upper crust and relatively little tectonic deformation; and a late rift stage that is characterised by tectonic deformation, synchronous with the deposition of a thick pile of volcanic and sedimentary rocks (1074–1040 Ma). Compared to modern rift examples, this rift is unusual in that the crust was thickened by ~ 15 km and overall extension was very limited. However, its structure and evolution are very similar to the near-contemporaneous Midcontinent Rift, which shows the addition of a similar quantity of magmatic material as well as crustal thickening and limited extension. For these Mesoproterozoic rifts, we suggest that magmatism was the dominant process, and that the extension observed was a response to magmatism-induced crustal thickening and the gravitational collapse of the crustal column. Other Proterozoic rifts show similar characteristics (e.g. Transvaal Rift), whereas most Phanerozoic rifts are dissimilar, showing instead a dominance of extension, with magmatism largely a result of this extension. This change in the style of rifting from the Precambrian to the Phanerozoic may relate to the influence of a typically cooler and stronger lithosphere, which has caused stronger strain localisation and a greater role for extension as the controlling factor in rift evolution. 相似文献
13.
巴尔喀什成矿带晚古生代地壳增生与构造演化 总被引：6，自引：4，他引：2
巴尔喀什成矿带是中亚成矿域重要的晚古生代斑岩铜钼成矿带。巴尔喀什成矿带晚古生代花岗岩类(石炭-二叠纪)主要为高钾钙碱性系列,晚期出现钾玄岩系列岩石,主要为I型花岗岩类;石炭纪处在同碰撞和火山弧环境,二叠纪为后碰撞环境。分析表明,博尔雷属于经典的岛弧花岗岩区,科翁腊德、阿克斗卡和萨亚克属于埃达克岩(Adakite)区。巴尔喀什成矿带内花岗岩类εNd(t)值为(-5.87～+5.94),εSr(t)值为(-17.16～+51.10)。以巴尔喀什中央断裂为界,成矿带东、西分带,断裂两侧具有不同的地壳生长历史:断裂以东的萨亚克和阿克斗卡地区εNd(t)值较高,具有亏损地幔组分特征,为古生代增生的新生陆壳;以西的科翁腊德和博尔雷εNd(t)值较低,主要是壳幔岩浆混合的结果,反映了古老基底的存在,主要为新元古代增生地壳。成矿带花岗岩类206Pb/204Pb、207Pb/204Pb和208Pb/204Pb比值范围分别为18.3346～20.9929、15.5213～15.7321和38.2874～40.0209,为造山带花岗岩类,具有与天山、阿尔泰和准噶尔花岗岩类的亲缘性。 相似文献
14.
The three intracratonic sedimentary basins located in central Baltoscandinavia, namely the Bothnian Gulf basin, the Bothnian Sea basin and the Baltic basin, developed in response to Middle Proterozoic and Late Proterozoic tectonic events, separated in time by about 800 Ma. Only the Baltic basin was subsequently affected by Caledonian orogenesis and Mesozoic rifting. Crustal extension was minor or did not take place during the Proterozoic basin evolution phases. However, according to the Moho topography, crustal thinning did take place. This was probably a result of subcrustal magmatism. On a craton-wide scale, the ages of granitoids, which intruded during the Middle Proterozoic basin formation, generally decrease from east to west. This fact, combined with the evidence provided by mantle-derived flood basalt magmatism, points to a moving asthenospheric diapir as the cause for basin development. Asthenospheric upwelling was probably also responsible for the second, Late Proterozoic, basin evolution phase, as evidenced by the lack of crustal thinning and extension, and the occurrence of tholeiitic intrusions. In addition, a Late Proterozoic thermally induced palaeo-high, located at about the position of the intracratonic basins, is compatible with indications from glaciations. As the ages of Late Proterozoic intracratonic basins also decrease from east to west across the craton, the location of asthenospheric diapirism during this time interval was also moving. For the Fennoscandian lithosphere, the presence of fundamental lithospheric weakness zones (e.g. terrane boundaries) might be an explanation for the formation of two generations of basins originating from asthenospheric upwelling at about the same location in the Fennoscandian Shield. The spacing and size of the Proterozoic intracratonic basins suggest that the asthenospheric diapirism was not deep seated. Therefore, sublithospheric convective processes might be the cause for the asthenospheric upwellings. Such processes are related to Rayleigh–Taylor instabilities in the sublithospheric mantle. Emplacement of an asthenospheric diapir causes a thermal bulge at the surface of the lithosphere. Modelling results demonstrate that erosion of the surficial high, succeeded by cooling of the lithosphere, can explain the accumulation of early Palaeozoic sediments in the Bothnian Sea basin, taking into account post-Ordovician vertical and lateral erosion of the basin fill. 相似文献
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华北板块周边地区板块的俯冲与碰撞对华北后来的岩石圈破坏可能产生了重要影响.对南口前岩体进行了锆石LA-ICP-MS U-Pb年代学和岩石地球化学研究,确定其时代及形成的构造背景.测年结果表明,岩石为晚三叠世(224±1 Ma)岩浆侵入的产物.地球化学研究表明岩石为高钾钙碱性系列,A/CNK值为0.98~1.07,属准铝质-过铝质花岗岩类.高Sr(394×10-6~545×10-6),低Yb(0.61×10-6~0.93×10-6),判断岩石属于埃达克岩类.岩石的εHf(t)值为-13.2~-6.9,二阶段模式年龄(TDM2)变化于1 669~1 825 Ma之间,判断岩石源于元古代地壳岩石的部分熔融.综合前人研究成果,认为岩石形成于古亚洲洋闭合后的造山后拉张环境. 相似文献
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The formation of manganese rocks and ores occurred during the whole geological history of the Earth. Five metallogenic epochs
(Early to Middle Proterozoic, Late Proterozoic, Early to Middle Paleozoic, Late Paleozoic, and Meso-Cenozoic) and 7 very important
phases (Early, Middle, and Late Proterozoic, Early to Middle Paleozoic, Late Paleozoic, Late Mesozoic, and Meso-Cenozoic)
can be distinguished. The phases of manganese ore genesis at many stratigraphic levels are closely related to the global climatic
and tectonic reconstructions (the breakup of the continent of Gondwana and periods of glaciations and aridization) and biotic
events (mass extinction of organisms). Based on carbon isotopic composition in manganese carbonates, participation of oxidized
organic carbon is established. 相似文献
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本文以内蒙古西部英巴地区一个典型剖面为例,开展了详细的构造解析和年代学研究,初步构建这一地区晚古生代-中生代的构造岩浆事件框架。这一地区至少发育三期岩浆活动和三期构造变形事件。锆石U-Pb定年结果和前人的资料显示,三期岩浆活动分别为石炭纪（325~313 Ma）的花岗闪长岩和花岗岩、早二叠世（291~277 Ma）的钾长花岗岩和中细粒花岗岩及早白垩世（~134~130 Ma）的伟晶岩和石英二长岩。第一期构造变形事件为NW-SE向挤压,发生在早二叠世之后,使花岗闪长岩和钾长花岗岩发生挤压变形,形成主体低角度北西倾的片麻理,局部发育同期褶皱,变形温度为450~600℃;第二期为NW-SE向伸展,大致发生在早白垩世,使片麻状花岗闪长岩和片麻状钾长花岗岩发生中高温（450~650℃）的糜棱岩化作用,形成南东倾的低角度韧性剪切带,具有正断性质,后被伟晶岩脉切穿。第三期为NW-SE向伸展,发生在早白垩世之后,形成北西倾的中角度脆性正断层,断距2~10米,并使伟晶岩变形为碎裂岩。 相似文献
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The south-eastern Bohemian Massif consolidated during the Late Variscan orogeny by the oblique collision of two continental crustal blocks after closure of an oceanic realm. One microcontinent comprises portions which are now distributed among Moravian and Moldanubian units and which are characterized by Late Proterozoic tectonothermal events, especially by granitoid intrusions. The other microcontinent includes the Gföhl gneiss and granulites (Gföhl nappe) of probable Early Palaeozoic protolith ages. Both continental blocks are separated by an ophiolite-like assemblage, which is preserved in portions of the Raabs unit.Oblique crustal stacking is accompanied by north-eastward propagation of nappes in a dextral transpressive regime. Exhumation of previously thickened crust is achieved by equally oriented bulk extension but partitioned in distinct displacement paths. Coeval stacking and extension at different crustal levels is suggested.Correspondence to: H. Fritz 相似文献