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91.
通过华北板块南缘北东地区的弧形构造特征、形成时代和瓦斯分布特征的研究,得出如下结论:1徐宿弧形构造限于丰沛断裂与蚌埠隆起北缘的五河断裂间,为形成于早三叠世后、晚侏罗世前的推覆构造;其形成与动力来源可能是扬子板块沿着郯庐断裂带向西或北西方向俯冲于华北板块之下的碰撞拼贴作用。2徐宿弧形推覆构造中和面外侧引张、内侧挤压的构造应力场是导致位于弧形内侧的宿东向斜内煤矿瓦斯富集、外侧闸河向斜瓦斯含量相对较少的主因之一;煤矿区内岩浆岩体(脉)的侵入改变了这种本应规律的瓦斯分布图案。岩浆活动和构造作用共同构建了华北板块南缘北东地区的构造和瓦斯分布图案。 相似文献
92.
本文介绍一种利用宽谱系岩墙群的空间展布特征进行靶区定位的数值方法.基于透岩浆流体成矿理论,岩浆-屏蔽层强相互作用过程中将涌现最大主压应力分布在竖直方向的近场应力场.在这种条件下,屏蔽层中的裂隙系统不同于传统矿田构造学描述的裂隙系统.依岩浆上升速率及屏蔽层岩石学结构和力学性质变化,屏蔽层中可出现不同类型的同成矿裂隙系统,后者往往被成矿期的脉岩充填.由于应力中心的作用力强度大于远离应力中心的部位,自生长裂隙和先存裂隙的密度呈现规律性的空间变化.这种变化控制了含矿流体的运动学特征.因此,可以将岩墙密度和延伸方向数作为定量化指标揭示含矿流体大规模聚集的空间位置,后者也是成矿作用的潜在发生部位.用滑动平均法绘制岩墙分布密度图和岩墙延伸方向密度图,将极密区作为有利找矿靶区,分析结果与地质学方法的预测结果高度相似.因此,可以认为本文提供的靶区圈定方法是一种简便有效的方法. 相似文献
93.
94.
利用-套基于非结构网格且能计算海水漫堤溢流的超高分辨率风暴潮漫滩数值模式模拟由9417号台风特大风暴潮引起的漫滩,结果与实测吻合良好。此外,选取超强台风强度并以9417台风路径为南路径,往北每间隔30 km为中路径和北路径设计了3条台风路径,进行了-系列数值模拟得出:近岸围堤加大了风暴潮、漫滩淹没对温州的威胁,而且由南路径引起的漫滩深度和中路径引起的漫滩面积影响最大。究其原因,近岸围堤对外海风暴潮在温州近海及瓯江口传播的阻隔和分流作用,两者综合变相加大了风暴潮往瓯江口北侧海域、瓯江北口、瓯江中上游的输送量。 相似文献
95.
晋冀蒙交界地区五期岩墙群的界定及其构造意义 总被引:13,自引:0,他引:13
以幔源岩浆侵位为标志的岩墙群是伸展作用的产物。根据同位素年龄测定 ,华北克拉通北缘晋冀蒙交界地区基性岩墙群可分为 :180 0~ 170 0 Ma,80 0~ 70 0 Ma,2 30 Ma,14 0~ 12 0 Ma,5 0~ 4 0 Ma五个年龄组。本文通过这五组岩墙群的地质、岩石及同位素地球化学特征的研究 ,探讨本地区地幔物质组分随时间的演变规律 ;并将本地区出现的五期伸展作用与华北克拉通乃至全球同期的重要构造事件进行对照。 相似文献
96.
不同结构离岸式潜堤消浪效果试验研究 总被引:1,自引:0,他引:1
在某保滩促淤工程中,应用了离岸式潜堤技术。为了验证其不同结构形式的消浪效果,通过物理模型试验,对斜坡堤、大圆筒以及板桩直立堤的3种潜堤断面,在3种不同水位、波高作用下的消波效果作观测比较,并对其结果进行分析研究,旨在为工程设计和建设提供科学依据。 相似文献
97.
98.
为初步探讨锆石铀含量在花岗岩型铀矿远景区预测方面的应用前景,以勘探研究程度较高的诸广南部花岗岩为样本,经花岗岩类样品概率统计显示产铀岩体锆石平均铀含量略大于贫铀岩体,总体差别不明显;样品分期次、岩性对比分析表明产铀岩体锆石平均铀含量也并非普遍高于贫铀岩体,印支期产铀岩体二云母花岗岩锆石平均铀含量甚至低于贫铀岩体;统计发现产铀岩体花岗岩岩脉中具有超高的锆石铀含量(平均铀含量3000×10-6以上)。初步分析认为依据花岗岩类锆石铀含量暂不能有效判别诸广山复式岩体成矿能力;岩脉锆石铀含量超高可能是铀矿找矿的重要标志,因而具超高锆石铀含量的花岗岩岩脉是否发育可能是该区域寻找工业铀矿床的关键。 相似文献
99.
Petrogenesis of Early Cretaceous mafic dikes in southeastern Jiaolai basin,Jiaodong Peninsula,China 总被引:1,自引:0,他引:1
Mafic dikes of mainly Early Cretaceous age (130–110 Ma) are widely developed on the Jiaodong Peninsula, China. Previous studies of the dikes, which have focused mainly on occurrences in the Jiaobei uplift and in the Sulu orogenic belt, have thoroughly examined their petrogenesis and geodynamic setting. This study identified four previously unknown mafic dikes (dolerite and lamprophyre) in southeastern Jiaolai basin (near Haiyang city), Jiaodong Peninsula. Detailed geochemical and geochronological analyses were conducted to determine the petrogenesis of the dikes and to infer their geodynamic setting. Zircon U–Pb dating by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) indicates that the dikes were emplaced at ~126 Ma. The dikes are characterized by low SiO2 contents (44.3–52.3 wt.%), high contents of MgO (7.28–10.13 wt.%), Cr (267–652 ppm), and Ni (93–335 ppm), and high Mg# values (63–73); they are enriched in large ion lithophile elements (LILEs; Ba, K, and Sr), depleted in high field strength elements (HFSEs; Nb, Ta, P, and Ti), and are characterized by high (87Sr/86Sr)i isotope ratios (0.707226–0.708222), low εNd(t) values (?12.3 to ?13.6), and zircon εHf(t) values (?15.6 to ?23.6). These features suggest that the dikes were derived from enriched subcontinent lithospheric mantle (SCLM). The wide range of Rb/Sr (0.04–0.18) and Ba/Rb (5–34) ratios, and the low and limited range of Dy/Yb (1.93–2.52) and K/Yb (5.71–11.99) ratios of the dikes indicate that the magmas originated from a low degree of partial melting of an amphibole- and phlogopite-bearing lherzolite in the spinel–garnet transition zone. The parental magma might have experienced fractionation of olivine and clinopyroxene during its ascent without significant crustal contamination. Evident depletion of Nb–Ta and Zr–Hf, low and limited range of Th/Yb ratios, elevated Ba/La ratios, constant chondritic Zr/Hf ratios, and a large range of Hf/Sm ratios further indicate that the mantle sources of the dikes were altered by carbonate-related metasomatism from subducted slab-derived fluids, which were most likely related to subduction of the Palaeo-Pacific plate during the Mesozoic. The mafic dikes in the southeastern Jiaolai basin resemble the arc-like mafic dikes in the Jiaobei terrain and the Sulu orogenic belt, and possibly indicate lithospheric thinning induced by slab rollback of the Palaeo-Pacific plate. 相似文献
100.
Widely applied in maintaining estuarial waterway depth, the spur dike has played an important role in currents and sediment exchange between channel and shoal and sediment back-silting in the channel. Through establishing a generalized physical model at a bifurcated estuary and conducting current tests under the joint action of runoff and tide, the influence of the spur dike length on current exchange between channel and shoal is analyzed. Results show that when the spur dike length reaches a certain value, the direction of the flow velocity shear front between the channel and shoal will change. The longer the spur dike, the larger the transverse fluctuating velocity at the peak of flood in the channel shoal exchange area, while the transport of the transverse hydrodynamics is obvious in the process of flood. There is an optimum length of spur dike when the shear stress in the channel and the longitudinal velocity in flood and ebb reach the maximum, and the flow velocity will decrease when the spur dike length is smaller or larger than the optimum. For a certain length of spur dike, the larger the channel shoal elevation difference, the larger the peak longitudinal flow velocity in the middle of the navigation channel in flood and ebb. However, the transverse flow velocity will first decrease and then increase. The transverse transportation is obvious when the channel shoal elevation difference increases. 相似文献