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31.
太平洋板块俯冲与中国东部中生代地质事件 总被引:44,自引:0,他引:44
中国东部至少自侏罗纪开始就一直处于俯冲大洋板块之上,但是有关俯冲板块对其影响程度一直有不同的认识。最近的研究表明,太平洋海山岛链的时空分布显示太平洋板块的漂移方向曾发生多次转折,这些转折与白垩纪中国东部的构造演化和岩浆事件有着密切的时空耦合关系。从时代和力学性质上看,太平洋板块俯冲方向的改变在很大程度上控制着中国东部中生代的盆地演化和郯庐断裂活动等重要地质事件。这些认识为理解中国东部构造演化提供了新的视角,包括岩石圈减薄的机制、郯庐断裂的演化,以及燕山期大规模岩浆活动等。本文重点分析了太平洋板块俯冲与中国东部中生代岩浆活动的对应关系。在125~140Ma太平洋板块向南西方向俯冲,造成中国东部岩石圈减薄,软流圈卸载上涌,发生减压部分熔融;约125Ma,太平洋板块漂移方向发生了大幅度转折,形成安第斯式的俯冲挤压,岩石圈停止减薄和减压部分熔融,出现岩浆宁静期。随着俯冲的深入,到110Ma前后俯冲板块后撤,形成弧后拉张,岩浆活动又重新开始。 相似文献
32.
H. Zöllner K. Reicherter P. Schikowsky 《International Journal of Earth Sciences》2008,97(5):1013-1027
The pre-Alpine structural and geological evolution in the northern part of the North German Basin have been revealed on the
basis of a very dense reflection seismic profile grid. The study area is situated in the coastal Mecklenburg Bay (Germany),
part of the southwestern Baltic Sea. From the central part of the North German Basin to the northern basin margin in the Grimmen
High area a series of high-resolution maps show the evolution from the base Zechstein to the Lower Jurassic. We present a
map of basement faults affecting the pre-Zechstein. The pre-Alpine structural evolution of the region has been determined
from digital mapping of post-Permian key horizons traced on the processed seismic time sections. The geological evolution
of the North German Basin can be separated into four distinct periods in the Rerik study area. During Late Permian and Early
Triassic evaporites and clastics were deposited. Salt movement was initiated after the deposition of the Middle Triassic Muschelkalk.
Salt pillows, which were previously unmapped in the study area, are responsible for the creation of smaller subsidence centers
and angular unconformities in the Late Triassic Keuper, especially in the vicinity of the fault-bounded Grimmen High. In this
area, partly Lower Jurassic sediments overlie the Keuper unconformably. The change from extension to compression in the regional
stress field remobilized the salt, leading to a major unconformity marked at the base of the Late Cretaceous. 相似文献
33.
Albrecht Steck 《Swiss Journal of Geoscience》2008,101(2):515-546
This study presents a review of published geological data, combined with original observations on the tectonics of the Simplon
massif and the Lepontine gneiss dome in the Western Alps. New observations concern the geometry of the Oligocene Vanzone back
fold, formed under amphibolite facies conditions, and of its root between Domodossola and Locarno, which is cut at an acute
angle by the Miocene, epi- to anchizonal, dextral Centovalli strike-slip fault. The structures of the Simplon massif result
from collision over 50 Ma between two plate boundaries with a different geometry: the underthrusted European plate and the
Adriatic indenter. Detailed mapping and analysis of a complex structural interference pattern, combined with observations
on the metamorphic grade of the superimposed structures and radiometric data, allow a kinematic model to be developed for
this zone of oblique continental collision. The following main Alpine tectonic phases and structures may be distinguished:
It is suggested that movements of shortening in fan shaped NW, W and SW directions accompanied the more regular NW- to WNW-directed
displacement of the Adriatic indenter during continental collision.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Editorial Handling: Stefan Bucher 相似文献
1. | NW-directed nappe emplacement, starting in the Early Eocene (~50 Ma); |
2. | W, SW and S-verging transverse folds; |
3. | transpressional movements on the dextral Simplon ductile shear zone since ~32 Ma; |
4. | formation of the Bergell – Vanzone backfolds and of the southern steep belt during the Oligocene, emplacement of the mantle derived 31–29 Ma Bergell and Biella granodiorites and porphyritic andesites as well as intrusions of 29–25 Ma crustal aplites and pegmatites; |
5. | formation of the dextral discrete Rhone-Simplon line and the Centovalli line during the Miocene, accompanied by the pull-apart development of the Lepontine gneiss dome – Dent Blanche (Valpelline) depression. |
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Editorial Handling: Stefan Bucher 相似文献
34.
辽东南地区晚中生代地层发育不甚完全,具有两期盆地叠合演化的特征,即早中侏罗世和早白垩世两个演化阶段,经历了2次伸展裂陷和2次挤压反转。在详细研究辽东南地区各盆地岩石地层序列、生物化石组合特征、年代地层格架以及区域地层对比的基础上,讨论了盆地的演化阶段和演化规律,指出是古太平洋板块向东亚大陆边缘不同方向的俯冲与走滑,以及来自北方西伯利亚板块的持续碰撞挤压的联合构造应力场制约了中国东北地区晚中生代盆地的裂陷过程和构造反转的演化,进而为揭示华北克拉通晚中生代岩石圈演化的动力学机制提供参考依据。 相似文献
35.
Based on the determination of composition of volcanic volatiles and petrologic estimation of the total mass of volatiles erupted,
we showed important advances in the study of the impact of Mesozoic and Cenozoic volcanic activities on paleo-environmental
changes in China. The volcanic activities include western Liaoning and Zhangjiakou Mesozoic intermediate-acidic explosive
eruptions, southern Tibet and Shanwang Cenozoic volcanism, and Mt. Changbai volcanic eruption around one thousand years ago.
The paper predominantly discusses the earth’s surface temperature changes, ozone depletion, acidic rain formation and mass
mortalities of vertebrate induced by the Mesozoic and Cenozoic volcanism in China.
__________
Translated from Bulletin of Mineralogy, Petrology and Geochemistry, 2007, 26(4): 319–322 [译自: 矿物岩石地球化学通报] 相似文献
36.
辽宁中部一些地区的含煤地层以前被认为是白垩系下统的沙海组、阜新组,该观点导致区域地层对比混乱。通过对该区含煤地层组合特征综合分析,认为其应属下侏罗统北票组含煤岩系。此结论对进一步明确该地区找煤方向、确定找煤远景区具有重要意义。 相似文献
37.
38.
喜马拉雅山是由印度板块和欧亚板块相碰撞而形成,这已被当代多数有关科学家所认识。一些测量数据也表明喜马拉雅山现在仍在快速隆升。而喜马拉雅山主峰——珠穆朗玛峰的高程的测定,也成为当代地学界的热点。本文结合最新资料对精确测定珠峰高程的一些问题,诸如水准基面、峰顶标志和积雪等进行了讨论。 相似文献
39.
豫西后造山阶段存在变质核杂岩吗? 总被引:2,自引:1,他引:1
不少学者用变质核杂岩模式解释豫西造山阶段基底隆起和与之相伴的盆岭构造的构造格局。介一本区基底隆起的形态、机制、时限和地壳剥露层次均没有变质核杂岩特征与基底隆起相伴的断陷人舅地也不同于变质核杂岩模式中的半地堑。 相似文献
40.
Variability in Early Amazonian Tharsis stress state based on wrinkle ridges and strike-slip faulting
We present evidence for a decrease in the magnitude of Tharsis-circumferential compressive stress during the Late Hesperian to the Middle Amazonian based on chronologic changes in the predominant style of faulting in southern Amazonis Planitia. Using high-resolution MOLA topography, we identify a population of strike-slip faults that exhibit Middle Amazonian-aged displacements of regional chrono-stratigraphic units. These strike-slip faults are adjacent to an older population of previously documented Late Hesperian-aged thrust faults (wrinkle ridges). Along-strike orientations of these thrust and strike-slip faults reveal the Tharsis-radial stress to be the area's most compressive remote principal stress and that this stress orientation and magnitude persisted throughout the Late Hesperian to the Middle Amazonian. We show that the change in the predominant style of faulting from thrust faulting to strike-slip faulting during this time requires a decrease of the Tharsis-circumferential compressive stress to a magnitude less than lithostatic load, with negligible change in stress orientation. 相似文献