共查询到19条相似文献，搜索用时 265 毫秒
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利用电子探针等方法研究了青岛榴辉岩相变质古洋壳(蛇纹岩、C类榴辉岩和基性糜棱岩)的岩石学和地球化学特征。确定了它们为华南陆块与华北陆块拼合前的古洋壳,当其俯冲于华北陆块之下时在深部发生碱质交代及低温高压变质作用(C类榴辉岩相)。 相似文献
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提出胶东—苏北构造带以广泛出露榴辉岩和超基性岩、普遍发育韧性剪切带和糜棱岩带为特征,具混杂岩特点。它经历了早元古代大陆推覆构造事件(2000～2400Ma)、早元古代末低角闪岩相变质热事件(1800～2000Ma)和元古代末大陆推覆构造事件(6O0～800Ma)。该构造带是华北陆块与华南陆块之间的过渡带。 相似文献
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本文报道了胶东—苏北古碰撞带附近存在的高温低压变质的麻粒岩相、高温高压变质的A—B类榴辉岩相和高压低温变质的C类榴辉岩相三种变质相系,以及与高温低压麻粒岩相有关的Ⅰ型花岗岩带,它们在空间上相协调,在时间上相一致。其经历了早元古代早期的华南—华北陆块碰撞事件、早元古代角闪岩相变质事件和早元古代末期大陆推覆构造事件,使得高温低压麻粒岩相岩石发生退变质作用,低温高压C类榴辉岩相岩石发生进变质作用,蓝闪石片岩消失,并导致高温高压的A—B类榴辉岩相和高压低温的C类榴辉岩相在空间上相叠置。 相似文献
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胶东—鲁南榴辉岩带的岩石学矿物学地球化学及其成因研究 总被引：1，自引：0，他引：1
本文报道了笔者对分布于山东荣成、文登、威海、青岛、胶南、诸城、日照和莒南等地的榴辉岩所作的岩石学矿物学和地球化学研究。确定了这一巨型榴辉岩带是由两条相互重合的榴辉岩带所构成;一条为高温高压成因的A—B类榴辉岩带;另一条为低温高压成因的C类榴辉岩带。它们形成于早元古代早期华南陆块向华北陆块的俯冲,并经受了早元古代角闪岩相变质作用的迭加。早元古代早期华北陆块发生向南运动的大陆推覆体构造,使两种不同成因类型的榴辉岩带在空间上重迭。最后推测这一榴辉岩带的分布代表着我国东部华北陆块与华南陆块的分界界限。 相似文献
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青岛C类榴辉岩的岩石学矿物学及其地质意义 总被引：2，自引：0，他引：2
本文利用X荧光光谱定量分析、电子探针分析和X衍射分析对青岛C类榴辉岩作了岩石学、岩石化学和矿物化学研究,计算了青岛C类榴辉岩的成岩温度、压力条件及古地温梯度,最后提出了其成因是早元古代早期华南陆块向华北陆块俯冲时,大洋碱性橄榄玄武岩在低温高压环境发生变质作用形成C类榴辉岩和蓝闪石片岩。早元古代的变质作用使C类榴辉岩平衡温度升高,蓝闪石片岩消失。 相似文献
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鲁苏榴辉岩套以广泛分布各类榴辉岩、密切伴生石榴石橄榄岩、石榴石麻粒岩等高压岩石组合 ,普遍发育韧性变形带 ,大量出露燕山晚期碱性花岗岩及深源脉岩为特征。它已经历三迭纪早期华南陆块与华北陆块的碰撞事件、大陆逆掩推覆构造事件及后期白垩纪早期开始的大陆伸展构造事件 ,是我国华南陆块与华北陆块之间的重要过渡单元。 相似文献
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讨论山东诸城胶南混杂岩系中的榴辉岩属地壳角闪岩相变质成因,其Sm—Nd等时年龄为222±6Ma,~(143)Nd/~(144)Nd初始比值为0.51136±0.00003,θ(T) 为-19.4±0.5,代表了早三叠世华南陆块与华北陆块碰撞拼合,并发生高压变质作用。后期的陆壳推覆及伸展构造使深部榴辉岩上升侵位于胶南混杂岩系中。 相似文献
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《海洋地质与第四纪地质》2017,(4)
中国东部的苏鲁造山带印支期先后经历了大洋消减俯冲、大陆碰撞、陆壳深俯冲、陆内造山等复杂过程。综合苏鲁造山带的构造地质学、岩石学、岩相古地理学、年代学进展,发现以下事实用传统的华南向华北俯冲难以解释:(1)徐淮地区形成了明显的朝北西拓展的逆冲构造变形,此外,苏鲁造山带中还存在大量的北西向逆冲推覆构造;(2)苏鲁造山带中出露的白垩纪花岗岩中来自古元古代的继承锆石,以及Sr、Nd、Pb同位素示踪结果都显示与华北地块南缘地质体更为相似;(3)苏鲁造山带北侧的胶莱盆地以及胶北隆起缺乏晚古生代到中生代的弧后火山岩证据;(4)华北南缘三叠纪时期的古地理环境更接近被动大陆边缘。基于这些事实,本文认为,晚古生代-早三叠世早期苏鲁段的商丹洋可能向南东俯冲,不同于秦岭-大别段的商丹洋向北俯冲,消减到秦岭-大别微陆块苏鲁段之下,发生华北地块与该微陆块的拼合,华北地块整体向南东楔入秦岭-大别微陆块,导致大别-苏鲁超高压岩石垂向折返剥露;中三叠世-晚三叠世,勉略洋自东向西的剪刀式闭合,华南地块向北秦岭-大别微陆块俯冲拼合,并逐渐将华南地块与华北地块之间的秦岭-大别微陆块向西、向北侧向挤出,到了中生代华北地块持续向南东俯冲并楔入华南地块,将苏鲁-大别造山带沿郯庐断裂错断并最终形成该区总体构造格局。 相似文献
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The smear zone, which develops during the placement of the prefabricated vertical drain (PVD) in the ground using a steel mandrel, is a significant factor that influences the performance of PVDs. The determination of the width and hydraulic conductivity of smear zone is an important consideration in designing ground improvement by preloading with PVDs. Thus, the extent and hydraulic conductivity of the PVD smear zone have received significant attention; however, there is still uncertainty and the topic remains discrepant among investigators. There is limited or no smear zone hydraulic conductivity data that is directly produced by laboratory or field tests. In this study, a laboratory smear zone model experiment that was developed as a performance test for determining the extent of the smear zone and measuring directly its hydraulic conductivity was used. Based on the findings obtained from two different materials (Craney Island dredgings and Hydrite R kaolinite soil), it is indicated that the disturbed zone is made up of two areas, namely smear zone and transition zone, and that the hydraulic conductivity in these areas is lower than the undisturbed soil. The ratio of the hydraulic conductivity of the smear and transition zones to that of the undisturbed soil was found to vary between 0.32 and 0.50 and between 0.57 and 0.82, respectively in different soils. The diameter of the smear zone was found to be 2.3–3.3 times higher than the equivalent diameter of the mandrel depending on the soil. The diameter of the transition zone extended 5.2–7.3 times the equivalent diameter of mandrel again depending on the soil. These directly measured values, in general, are supportive of the published values based on indirect means and the test device can be used to study the impact of mandrels of different size and shape and other factors by minor modification. 相似文献
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A physical parameter, μb, which was used to meet the forcing of primary short waves to be off-resonant before wave breaking, has been considered as an applicable parameter in the infra-gravity wave generation. Since a series of modulating wave groups for different wave conditions are performed to proceed with the resonant mechanism of infra-gravity waves prior to wave breaking, the amplitude growth of incident bound long wave is assumed to be simply controlled by the normalized bed slope, βb. The results appear a large dependence of the growth rate, α, of incident bound long wave, separated by the three-array method, on the normalized bed slope, βb. High spatial resolution of wave records enables identification of the cross-correlation between squared short-wave envelopes and infra-gravity waves. The cross-shore structure of infra-gravity waves over beaches presents the mechanics of incident bound- and outgoing free long waves with the formation of free standing long waves in the nearshore region. The wave run-up and amplification of infra-gravity waves in the swash zone appear that the additional long waves generated by the breaking process would modify the cross-shore structure of free standing long waves. Finally, this paper would further discuss the contribution of long wave breaking and bottom friction to the energy dissipation of infra-gravity waves based on different slope conditions. 相似文献
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海底天然气水合物稳定带的特征分析 总被引：14，自引：1，他引：14
水合物稳定带（HSZ）控制着海底天然气水合物的成矿作用和分布规律，其厚度及分布范围决定了天然气水合物的蕴藏量，所以水合物稳定带的分析对天然气水合物的成矿与分布规律、成因与演化机制以及资源研究具有重要的指导意义。水合物稳定带本身受海底温度、压力和甲烷量等因素的影响，其变化会影响水合物稳定带的范围、稳定带底界的位置，并制约着天然气水合物的稳定性和甲烷气的释放。 相似文献
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黄河冲淡水及其混合锋面的观测研究 总被引：1，自引：0，他引：1
本文主要论述了黄河冲淡水入海后混合锋面的变异特性。作者于1983、1986、1987年秋进行了三次跟踪定位观测,获得了有益的資料。发现淡水舌向SE,E,NE方向伸延;大量泥沙在距岸10km的海域內运移。 相似文献