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经过详细的野外地质调查和室内薄片观察,在大别山北淮阳带西段原“定远组”变质火山岩中发现新元古代侵位的浅变质花岗岩.对其中两个浅变质花岗岩样品进行了锆石SHRIMPU-Pb定年和初步的岩石学研究.结果表明,这些浅变质花岗岩经过了强烈的构造变形和绿帘角闪岩相变质作用,它们的形成时代分别为(726±6)和(758±12)Ma,并且与北淮阳带东段庐镇关杂岩的形成时代一致.结合前期发现的(635±5)Ma浅变质(橄榄)辉长岩,证明北淮阳带至少存在两类新元古代侵入岩,即726～758Ma的变质花岗岩和635Ma的变质辉长岩.这些新元古代岩石出露于变质的奥陶纪岩火山岩带(原“定远组”)中,二者之间为构造接触以及分别形成于不同的大地构造背景,并且它们与华南陆块北缘湖北随州-枣阳一带发育的二期大规模新元古代中、晚期基性岩墙群和花岗岩的时代以及大别山超高压岩石的原岩时代一致.这进一步证明,它们可能是印支期华南陆块发生俯冲的初始阶段最早被拆离、解耦的岩片,并在南、北陆块汇聚、碰撞及造山过程中被推覆到华北陆块南缘古生代浅变质岩系之上.
After detailed field geological survey and in-house thin film observation, the Neoproterozoic emplacement metamorphic granite was found in the original “Dingyuan Formation” metamorphic volcanic rocks in the western section of Beihuaiyang Belt of the Dabie Mountains. Two of the two metamorphic granite samples Zircon SHRIMPU-Pb dating and preliminary petrological studies. The results show that these super-metamorphic granites experienced strong tectonic deformation and metamorphism of epidrine amphibolite, and their formation ages were (726 ± 6) and (758) ± 12) Ma, and coincides with the age of the Luzhauanuan complex in the eastern segment of the Northern Huaiyang Belt.According to the (635 ± 5) Ma superficial metamorphic (olivine) gabbro previously discovered, it is proved that there are at least two Neoproterozoic intrusive rocks, metamorphic granites of 726 ~ 758Ma and metamorphic gabbro of 635Ma, these Neoproterozoic rocks are exposed in metamorphic Ordovician volcanic rocks (formerly “Dingyuan Formation”), both of which And they are formed on different tectonic backgrounds respectively and they are associated with the large-scale Neoproterozoic Neoproterozoic Mesozoic and Late Mafic dikes and granite developed in the Suizhou-Zaoyang area, northern part of the South China Block. As well as the original of the EHV rocks in the Dabie Mountains This further proves that they may be the earliest detachment and decoupling fragments in the initial stage of Indosinian continental block subduction and are pushed over to the North China during the convergence of the South and North continental blocks, collision and orogeny On the southern margin of Paleozoic metamorphic shallow metamorphic rocks.