Latest Caledonian to Present tectonomorphological development of southern Norway     

Roy H. Gabrielsen  Jan Inge Faleide  Christophe Pascal  Alvar Braathen  Johan Petter Nystuen  Bernd Etzelmuller  Sejal O'Donnell 《Marine and Petroleum Geology》2010

The regional resultant stress field of the northeastern North Atlantic has shifted significantly throughout the Phanerozoic. In Fennoscandian parts of the Caledonian orogen, mountain building, which was characterized by NW-SE contraction (reference to present North), was followed by a collapse with transport both parallel and transverse to the mountain chain. The Late Palaeozoic – Mesozoic saw several stages of E-W to NW-SE extension, varying in time and position. Local episodes of inversion are traceable in some cases, particularly in connection with deep-seated and long-lived zones of weakness. The Cenozoic has to a larger degree been affected by compression, including folding and basin inversion. Again some of the more pronounced effects of local inversion are related to pre-existing fault systems. Neogene uplift of the western mountainous area in Scandinavia can be unravelled by potential field study, AFT data and reflection seismic sections. Assuming that the region is close to isostatic equilibrium, the uplifted areas must be supported at depth by substantial volumes of low-density material within the crust or the mantle, close to the crust/mantle interface or close to the lithosphere/asthenosphere interfaces.  相似文献   

Segmentation and differential post-rift uplift at the Angola margin as recorded by the transform-rifted Benguela and oblique-to-orthogonal-rifted Kwanza basins   总被引：1，自引：0，他引：1  

M. Guiraud  A. Buta-Neto  D. Quesne 《Marine and Petroleum Geology》2010

We analyse tectonic and sedimentary field and subsurface data for the Angola onshore margin together with free-air gravity anomaly data for the offshore margin. This enables us to characterize the mode of syn-rift tectonism inherited from the Precambrian and its impact on the segmentation of the Angola margin. We illustrate that segmentation by the progressive transition from the Benguela transform-rifted margin segment to the oblique-rifted South Kwanza and orthogonal-rifted North Kwanza margin segments. The spatial variation in the intensity of post-rift uplift is demonstrated by the study of a set of geomorphic markers detected in the post-rift succession of the coastal Benguela and Kwanza Basins: Upper Cretaceous to Cenozoic uplifted palaeodeltas, erosional unconformities, palaeovalleys, Quaternary marine terraces and perched Gilbert deltas. The onshore Benguela transform margin has a distinctive, mainly progradational stratigraphic architecture with long-term sedimentary gaps and high-elevation marine terraces resulting from moderate Upper Cretaceous–Cenozoic to major Quaternary uplifting (i.e. 775–1775 mm/ky or m/Ma). By contrast, repeated synchronous episodes of minor Cenozoic to Quaternary uplift occurred along the orthogonal-rifted North Kwanza segment with its Cenozoic aggradational architecture, short-term sedimentary gaps and low-elevation Pleistocene terraces. Margin style likewise governs spatial variations in the volume of offshore sediment dispersed in the associated deep-sea fans. Along the low-lying North Kwanza margin, sedimentation of the broad Cenozoic to Pleistocene Kwanza submarine fan was probably governed by the width of the Kwanza interior palaeodrainage basin combined with the wet tropical Neogene climate. Along the high-rising Benguela margin, the small size of the Benguela deep-sea fan is related to the interplay between moderate continental sediment dispersal from long-lived small catchments and a warm, very arid Neogene climate. However, the driving forces behind the epeirogenic post-rift uplift of the Angola coastal bulge remain a matter of speculation.  相似文献   

南黄海中部隆起地层分布特征   总被引：11，自引：1，他引：10  

欧阳凯  张训华  李刚 《海洋地质与第四纪地质》2009,(1)

南黄海中部隆起是南黄海盆地构造最稳定的地区之一,也是下古生界含油气远景区之一,其找油前景引起人们极大的关注。应用小波分析等方法处理南黄海重磁异常场,揭示中部隆起区结晶基底起伏特征,同时结合区域地质以及地震剖面资料,对中部隆起地层分布特征提出了几点新认识:南黄海中部隆起结晶基底的起伏特征并非"平板"一块,其平面总体轮廓可概括为"三隆两坳";受印支运动的影响,中部隆起区发育的主要地层是震旦系-下二叠统,下三叠统青龙灰岩和上二叠统龙潭煤系已基本剥蚀殆尽;下古生界沉积中心大致位于结晶基底"坳陷"部位;上古生界受火山活动和岩浆侵入的影响,分布特征是分段而不连片;中部隆起分布着火山岩,分布特征是"东强西弱"。  相似文献   

Timing and mechanisms for the generation and modification of the anomalous topography of the Borborema Province,northeastern Brazil     

J.M. Morais Neto  K.A. Hegarty  G.D. Karner  F.F. Alkmim 《Marine and Petroleum Geology》2009

The results of apatite fission-track analysis in 14 granitic-gneissic samples from two regional transects across the Borborema Plateau, northeastern Brazil, show evidence for two dominant paleothermal events: a Late Cretaceous cooling event beginning sometime between 100 and 90 Ma, and a second cooling event in the Neogene. The distribution of the fission-track results suggests that the cooling events have a broad regional expression and are consistent with the geologic record in the Araripe Basin, western Borborema Province, which attests to a post-Albian uplift of the whole region. We hypothesize that the first event is due to the uplift and denudation of regional, permanent topography generated after the breakup of Brazil and Africa. Such topography is predicted by models of continental margin extension in which continental lithosphere thinning is followed by thickening of the adjacent hinterland lithosphere and crust (Kusznir, N.J., Karner, G.D., 2007. Continental lithospheric thinning and breakup in response to upwelling divergent mantle flow: application to the Woodlark, Newfoundland and Iberia margins. In: Karner, G.D., Manatschal, G., Pinheiro, L. (Eds), Imaging, mapping and modeling continental lithosphere extension and breakup. Special Publication 282, Geological Society, London, pp. 389–419.). In northeastern Brazil, this extension-engendered topography may have been amplified by magmatic underplating related to the Saint Helena and Ascension plumes. The Miocene cooling event (20–0 Ma) occurred at a time characterized by the transition from carbonate ramp to progradational clastic systems on the Pernambuco–Paraíba margin and the offshore Potiguar Basin. This same stratigraphic response characterizes the Neogene stratigraphy of many passive margins and attests to a global increase in the delivery of clastics to margins, the simplest explanation of which is a climate change that accentuated erosion of pre-existing topography. Thus, the present rugged landscape of northeastern Brazil is interpreted to be a product of this younger denudation event. A corollary of this study is that the history, distribution and delivery of clastics to the northern and northeastern margins of Brazil are a function of the regional development of the continental landscape during the Late Cenozoic.  相似文献   

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薄万举  杨国华 《大地测量与地球动力学》2008,28(6):11-15

??????Ms8.0?????????????????????????GPS??????α???????1???????????????????????????????????????????????180 mm?????2??????GPS??????????????????????????Σ????????????????3?????????????κβ??????????????????????????????Σ????????????????????,???????8???????????????????顣  相似文献   

利用两种时序InSAR技术进行地面抬升监测与研究     

张允涛  王宏昌  王新田  王博  梁菲 《测绘通报》2020,(10):157

近年来,地面沉降监测与治理在防灾减灾方面受到政府重视,但是对地面抬升现象及机理少有研究。本文采用PS-InSAR和NSBAS两种技术,利用Sentinel-1影像升、降轨数据对淄博市4个市辖区进行形变监测,并通过资料分析该区域的地面抬升与煤矿开采情况的一致性。  相似文献   

青藏高原莫霍面形态的重力模拟及其对探讨高原隆升机制的意义   总被引：10，自引：2，他引：10  

吕庆田  姜枚  高锐 《地球学报》1997,18(1):78-86

青藏高原是印度板块板欧亚板块碰撞形成的巨大变形带，岩石圈地幔的变形特征对高原的隆或意义重大。本文分析了远震ＰＫＰ走时残差沿高原中部剖面的变化，发现莫霍面的断错在整个高原是普遍存在的；利用人工地震资料作为约束，用重力资料对莫霍面的形态进行了反演模拟，认为岩石圈地幔的断错和叠覆可能是青藏高原隆升的重要机制；最后讨论了板块中部热和密度不均匀性以及地幔流动对青藏高原岩石圈变形的影响。  相似文献   

雪峰山陆内造山带变形特征及挤压推覆—伸展滑脱构造的物理模拟   总被引：13，自引：2，他引：13       下载免费PDF全文

冯向阳  孟宪刚  邵兆刚  王建平  朱大岗  赵建光 《地球学报》2001,22(5):419-424

本文分析了雪峰山陆内造山带的变形特征，认为雪峰山造山带是在克拉通边缘裂陷槽基础上发育起来的，历经了加里东陆缘褶皱始造山、印支－早燕山陆内褶断主造山、晚燕山－早喜马拉雅陆内盆后（重）造山等过程而最后定型的。中生代以来，岩石圈向西北的俯冲，地壳层次向西挤压产生基底滑脱、推覆增厚，进而在松弛伸展过程出现山链两侧双极性的重力滑脱。在分析变形特征的基础上，对本区的挤压推覆－伸展滑脱构造进行了物理模拟实验，实验表明，来自于SE方向的挤压作用是产生大规模的推覆－滑脱构造的动力来源。在后期的应力松弛阶段，产生伸展滑脱构造。  相似文献   

江南隆起带褶皱基底变质变形温压条件研究   总被引：6，自引：0，他引：6  

李民  章泽军 《地球学报》2006,27(6):543-550

江南隆起带褶皱基底变质变形温压环境是地学界所关注的重要基础地质问题。作者通过对该区有代表性剖面中样品的伊利石结晶度指数、b0值、流体包裹体测温以及变质矿物相的分析,认为该区变质变形具非均匀性,但总体处于低温、低中压环境(估计温度为300~400℃,压力为3~5kbar,地热梯度为25℃/km)。结果还表明,褶皱基底中块体的垂向相对运动约为2km,造山过程表现为大范围的整体抬升,不同的构造单元有大致相近的变质变形环境。因此,江南隆起带褶皱基底这一宏观变形强烈、微观变形甚弱的现象属于低温下准塑性变形结果。  相似文献   

Lower bound solutions for uplift capacity of strip anchors adjacent to sloping ground in clay     

Jagdish Prasad Sahoo  Sunil Khuntia 《Marine Georesources & Geotechnology》2018,36(4):405-416

Numerical solutions have been obtained for the vertical uplift capacity of strip plate anchors embedded adjacent to sloping ground in fully cohesive soil under undrained condition. The analysis was performed using finite element lower bound limit analysis with second-order conic optimization technique. The effect of anchor edge distance from the crest of slope, angle and height of slope, normalized overburden pressure due to soil self-weight, and embedded depth of anchor on the uplift capacity has been examined. A nondimensional uplift factor defined as F_cγ owing to the combined contribution of soil cohesion (c_u), and soil unit weight (γ) is used for expressing the uplift capacity. For an anchor buried near to a sloping ground, the ultimate uplift capacity is dependent on either pullout failure of anchor or overall slope failure. The magnitude of F_cγ has been found to increase with an increase in the normalized overburden pressure up to a certain maximum value, beyond which either the behavior of anchor transfers from shallow to deep anchor or overall slope failure occurs.  相似文献