台湾海峡地区新生代的构造演化

根据采集反射剖面,结合区域地质资料,分析了晋江凹陷、九龙江凹陷、新竹凹陷、台中凹陷和台湾凹陷为半地堑结构。新竹凹陷和台中凹陷下拗,演变为前陆盆地。晋江凹陷和九龙江凹陷因岩石圈上隆,其沉积较薄。这种模式决定了在台湾海峡地区,西部的生油气层为下第三系,而东部的生油气层为下第三系和上第三系。     

陕西省数字地震台下方壳幔速度结构研究

利用广义反、透射系数的传递矩阵计算理论地震图，用快速模拟退火法搜索最佳模型，通过与地震台站实际记录的P波波形进行拟合对比，反演了陕西省13个数字地震台下方的P波速度结构。台站分布区域涉及到秦岭造山带、渭河盆地及鄂尔多斯地台三个构造区域。结果显示，3个构造区的地下速度结构差异明显，呈现了各自的构造特点。其中秦岭造山带上地壳乃至地表速度高，中下地壳出现多个低速层，可能与岩石脱水、构造滑脱带等有关；渭河盆地内上中地壳高低速度层交替出现，反映了断层活动在浅部的影响；鄂尔多斯地台有部分台站保持稳定的匀速构造。反映了古老地台地层稳定发展的特性，部分台站受到后期改造，低速层位增多。因为变化剧烈的台站分布在盆地的南部和西部。而且震源机制解显示该区主应力场方向为近东西向，可以说秦岭北缘的断裂作用以及后来来自青藏高原的挤压应力是导致渭河盆地形成和发展的主要因素。最后我们讨论了速度结构与强震、地震分布以及不同构造演化的关系。     

Fault population investigation and estimating magnitude of extension in Guma Graben, Central Afar, Ethiopia

Extension in the Afar depression occurs on steeply dipping normal faults of many scales. An estimate for cumulative extension can be derived by summing the heave of these faults using digital topographic data, supplemented by field observations of fault dip. If it can be established that the distribution of faults exhibits self-similarity, an estimate of the contribution from faults too small to appear on the digital imagery can be incorporated into the integrated estimate for cumulative extension. A field study of faulting was undertaken within the Dobe and Guma grabens of Central Afar. A fractal dimension of 0.48 was obtained for the measured population of fault throws (n = 92) in 3 traverses totaling 42 km, a value interpreted to represent the dominant contribution to extension from faults with large throw. The local extension rate across Guma graben is estimated to be between 0.06 and 0.24 mm/year. The higher topographic position of the floor of Guma graben, relative to the sediment filled, adjacent floors of Dobe and Immino grabens is perhaps an indication of a slower rate of extension across Guma graben as compared to Dobe and Immino grabens, assuming they all initiated at the same time.     

广东梅县嵩溪早侏罗世火山活动及其地质构造与成矿意义

从熔岩——玄武岩的岩石学、岩石化学、微量元素、稀土元素和锶同位素组成，以及火山旋回中玻璃碎屑岩诸方面特征，详细地研究了下侏罗统含矿层位内海底基性火山活动，阐述矿区玄武岩形成环境为夭折的大陆裂谷前期地壳槽形裂陷地堑系——裂陷槽。并讨论该裂陷槽环境中基性火山活动的银锑成矿意义     

Hydrogeological evolution of the Luni river basin,Rajasthan, western India: A review

The Luni river basin has been evolved as a result of typical hydrogeomorphic processes of arid zone, operating under the influence of active tectonic lineaments. A detailed analysis of stream morphology in relation to geology and lineaments carried out on selected windows indicated the morphological control of the streams while flowing over the lineaments from the eastern to the western part of the basin. Typical valley fills indicated by dark green tone on digitally processed images and the pediments showing greenish white tone appear in sharp contrast and indicate respectively the graben and horst structures. A detailed identification of lineaments for the georesources and geological evaluation has been carried out. Earlier analysis carried out on Bouguer anomalies correlate with graben and horst structures in the subsurface. Quaternary sequences have been dated from 80 ka to 3 ka indicating a range of fluvial to aeolian deposits reflecting prevailing climatic conditions. However, the changes in sediment type from coarse and mixed of all size grades to fine in a vertical litho-column warrant further studies on fine resolution stratigraphy and high resolution stratigraphy for understanding climatic variations in the region     

半地堑式断陷盆地的油气成藏模式--以松辽盆地梨树断陷为例

半地堑式断陷盆地是松辽盆地深部断陷的主要类型，是今后油气勘探重点。以梨树断陷为例，根据半地堑式断陷盆地的构造和层序地层发育特点，针对此类盆地的生储盖组合规律，总结出该类盆地中主要存在有滚动背斜油气藏、断层油气藏、超覆型上倾尖灭岩性油气藏、相变型上倾尖灭岩性油气藏、透镜型岩性油气藏、潜山油气藏等6种类型；探讨了半地堑式断陷盆地的油气成藏模式。     

Analysis Method for Predicting Strain in Interior Beds and Sub-Resolution Faults from Area Balance Theory in Extensional Basins

Extensional basins include mainly grabens and half grabens displaced along a lower detachment. Based on area balance theory, there is a linear relationship between a height of regional and the lower detachment h on the outside of the basin and “lost area S“ from the regional in the basin. The pre-growth beds above lower detachment are of the same extensional displacement so that an “S-h diagram“ can be used to determine the depth to lower detachment and to calculate the total extensional displacement of the beds above the lower detachment. The extensional displacement is dominated by the heave of various scale normal faults. The displacement of obvious faults can be immediately figured out from the measured bed-length. The requisite extension calculated by area balance is the layer-parallel strain, which could be accommodated by displacement on sub-resolution faults. Accordingly, the layer-parallel strain can help us predict the magnitude and distribution of sub-resolution faults on the basis of analysis of the structural style and rheological behavior.     

依舒地堑汤原、方正断陷古近纪边界断裂活动特征

依舒地堑位于黑龙江省东部,为一新生代断陷盆地,汤原断陷和方正断陷为其两个面积较大的二级构造单元。通过对汤原断陷和方正断陷边界断裂的研究,可以进一步了解依舒断裂带的形成和演化过程。研究发现,在始新世-渐新世依舒地堑边界断裂的活动整体上具有多中心、不均衡的特征,汤原断陷东部的边界断裂为控盆断裂,方正断陷东、西两侧的边界断裂对盆地的发展都具有一定的控制作用,但西部边界断裂为主要控盆断裂。断层的生长指数分析表明,依舒地堑内部的北西向断裂与边界断裂的活动具有一致的规律性,都起到协调边界断裂演化发展的作用。依舒地堑边界断裂转换引张方向是由莫霍面梯度带的倾斜方向所决定,梯度带的倾向与地堑的整体伸展方向相同。     

Geomorphic assessment of active tectonics in the Acambay graben,Mexican Volcanic Belt

Spatial variations of Quaternary deformation and tectonic activity of faults along the Acambay graben are assessed using geomorphic and morphometric approaches. The Acambay graben is an east–west trending structure of apparent Quaternary age, located in the central part of the Mexican Volcanic Belt, which gives rise to pronounced scarps over a distance of about 80 km. Continuing tectonic activity in the Acambay graben is confirmed by recent well documented seismic episodes. The intensity of active tectonics has been interpreted through a detailed geomorphic study of the fault-generated mountain fronts and fluvial systems. The combined geomorphic and morphometric data provide evidence for relative variations in tectonic activity among the Acambay graben faults. Geomorphic indices suggest a relatively high degree of tectonic activity along the Venta de Bravo and the Acambay–Tixmadeje faults, followed, in order of decreasing activity, by the Pastores, Temascalcingo and Tepuxtepec faults. Spatial variations within faults have also been identified, suggesting a higher level of tectonic activity at the tips of the faults. This pattern of variation in the relative degree of tectonic activity is consistent with field evidence and seismic data for the Acambay graben. Geomorphic evaluation of the Acambay graben faults suggests that the Acambay–Tixmadeje and Venta de Bravo faults, and specifically the tips of these faults and a central segment near the town of Venta de Bravo, should be considered as areas of potentially high earthquake risk. © 1998 John Wiley & Sons, Ltd.