A review of the Pan-African evolution of the Arabian Shield
A review of the Pan-African evolution of the Arabian Shield
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阿拉伯地盾泛非演变回顾
DOI：
10.2113/geoarabia0701103
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
Catherine Truffert
中科院分区：
文献类型：
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作者：
P. Nehlig;A. Genna;Fawzia Asfirane;C. Guerrot;J. Eberle;H. M. Kluyver;J. Lasserre;E. L. Goff;N. Nicol;N. Salpeteur;M. Shanti;D. Thiéblemont;Catherine Truffert
近期的野外工作以及对航磁、地质、构造、地球化学和地质年代学数据的综合与重新评估，为阿拉伯地盾的构造演化和地质历史提供了新的视角。尽管古元古代岩石存在于地盾的东部，但其地质演化主要集中在900至550百万年期间，在此期间几个构造地层地体发生了形成、拼合以及最终的泛非克拉通化。这些地体被主要的西北走向断层以及由蛇纹石化超镁铁岩（蛇绿岩）排列的北、西北和东北走向的缝合带所分隔。利用缝合带、断层带、叠覆盆地和连接深成岩体的岩石地层学和地质年代学进行的地体分析，有助于确定阿拉伯地盾的地质历史。蛇绿岩和火山弧的年龄在900至680百万年之间，其中阿西尔南部地体比北部的米甸地体和东部的阿尔赖因地体更古老。
680至610百万年期间地体的最终克拉通化导致了一个由北走向的纳比塔带、主要的西北走向的左旋压扭断层（早期的纳季德断层）组成的交织走滑断层网络，这些断层伴有片麻岩穹窿并与沉积盆地相关，还有北至东北走向的右旋压扭断层。在泛非克拉通化之后，广泛的碱性花岗岩化与张性拉分盆地中吉巴拉火山岩和沉积岩的沉积同时发生。地壳减薄受左旋转换断层的纳季德断层系统控制，该系统控制了吉巴拉盆地的形成，并与阿拉伯地盾中主要的东向至西北向岩墙群的侵位同时发生。伸展期以一次海侵结束，在此期间碳酸盐沉积在吉巴拉盆地中。减薄过程的持续可能解释了下古生界盖层海相地层的后续沉积。
我们对造山带分布和年代学的解释与早期研究中提出的并不完全一致。特别是，北走向的纳比塔和西北走向的纳季德断层带被证明是同一斜向压扭增生历史的一部分，而不是与地体增生和离散相关的两个不同事件。
Recent fieldwork and the synthesis and reappraisal of aeromagnetic, geologic, structural, geochemical, and geochronologic data have provided a new perspective on the structural evolution and geologic history of the Arabian Shield. Although Paleoproterozoic rocks are present in the eastern part of the Shield, its geologic evolution was mainly concentrated in the period from 900 to 550 Ma during which the formation, amalgamation, and final Pan-African cratonization of several tectonostratigraphic terranes took place. The terranes are separated by major NW-trending faults and by N-, NW- and NE-oriented suture zones lined by serpentinized ultramafic rocks (ophiolites). Terrane analysis using the lithostratigraphy and geochronology of suture zones, fault zones, overlapping basins, and stitching plutons, has helped to constrain the geologic history of the Arabian Shield. Ophiolites and volcanic-arcs have been dated at between 900 and 680 Ma, with the southern terrane of Asir being older than the Midyan terrane in the north and the Ar Rayn terrane in the east.
Final cratonization of the terranes between 680 and 610 Ma induced a network of anastomosing, strike-slip faults consisting of the N-trending Nabitah belt, the major NW-striking left-lateral transpressive faults (early Najd faults), lined by gneiss domes and associated with sedimentary basins, and N- to NE-trending right-lateral transpressive faults. Following the Pan-African cratonization, widespread alkaline granitization was contemporaneous with the deposition of the Jibalah volcanic and sedimentary rocks in transtensional pull-apart basins. Crustal thinning was governed by the Najd fault system of left-lateral transform faults that controlled the formation of the Jibalah basins and was synchronous with the emplacement of major E- to NW-trending dike swarms throughout the Arabian Shield. The extensional episode ended with a marine transgression in which carbonates were deposited in the Jibalah basins. Continuation of the thinning process may explain the subsequent deposition of the marine formations of the lower Paleozoic cover.
Our interpretation of the distribution and chronology of orogenic zones does not correspond entirely to those proposed in earlier studies. In particular, the N-trending Nabitah and NW-trending Najd fault zones are shown to be part of the same history of oblique transpressional accretion rather than being two distinct events related to accretion and dispersion of the terranes.