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首页> 外文期刊>Brazilian Journal of Geology >K'Mudku A-type magmatism in the southernmost Guyana Shield, central-north Amazon Craton (Brazil): the case of Pedra do Gavi?o syenogranite
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K'Mudku A-type magmatism in the southernmost Guyana Shield, central-north Amazon Craton (Brazil): the case of Pedra do Gavi?o syenogranite

机译：中北部亚马逊克拉通（巴西）最南端的圭亚那盾牌的K'Mudku A型岩浆作用：Pedra do Gavi？o榴辉岩的案例

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The Mesoproterozoic K'Mudku event (1490 - 1147 Ma) is represented by a britlle-ductile shear belt that cuts across the Paleoproterozoic units in the southernmost Guyana shield, central-north Amazon craton. This event produced mylonitization and cataclasites at low/medium- to high-grade metamorphic, and local within-plate magmatism. In the Amazonas State, Brazil, A-type magmatism chronologically associated to K'Mudku has been reported for the Pedra do Gavi?o and Samaúma syenogranites. However, the spatial relationship between K′Mudku event and A-type magma generation are not yet adequately clarified in the region. The Pedra do Gavi?o syenogranite is a high-K alkaline, metaluminous, reduced A-type granite with a post-collisional to within-plate geochemical signature. It has U-Pb zircons crystallization age of 1218 Ma and inherited zircons with ages between 1820 and 1720 Ma, which, together with the Sm-Nd data, suggest melting of Paleoproterozoic basement rocks of the Cauaburi Complex (1810 - 1780 Ma) regional unit. These data demonstrate that the effects of the A-type magmatism associated to the end of the Grenvillian-Sunsas orogeny, reported primarily in the southwestern margin of the Amazon craton, may also be extended for the central-northern part of the Amazon craton. Probably the generation or emplacement mechanisms of A-type magma occurred with some degree of involvement in the final stages of the K′Mudku event. However, this tectonic framework conception still needs more geological and geophysical investigations. Therefore, these news data should instigate to the return of geological research in the region, as well as to debate on the tectonic evolution and A-type granites production during the Ectasian-Stenian period in the central-north Amazon craton.
机译：中古生代的K'Mudku事件（1490年至1147年）以硬毛延展性剪切带为代表，该带剪切穿过最南端的圭亚那盾构，中北部亚马逊克拉通的古元古代生代单元。该事件在低/中到高级变质作用和局部板内岩浆作用中产生了髓鞘化和崩裂。在巴西的亚马孙州，据报道，佩德拉·杜·加维奥和萨摩玛正长花岗岩与卡穆德按时间顺序相关的A型岩浆作用。然而，该地区尚没有充分阐明K′Mudku事件与A型岩浆生成之间的空间关系。 Pedra do Gavi？o榴辉岩是一种高K碱，金属，还原的A型花岗岩，具有碰撞后到板内的地球化学特征。它的U-Pb锆石结晶年龄为1218 Ma，遗传的锆石年龄在1820和1720 Ma之间，再加上Sm-Nd数据，表明Cauaburi Complex（1810-1780 Ma）区域单元的古元古代基底岩石融化了。 。这些数据表明，主要在亚马逊克拉通的西南边缘报道的与格勒维利亚-桑萨斯造山运动结束有关的A型岩浆作用也可能扩展到亚马逊克拉通的中北部。可能是A型岩浆的生成或沉积机制，在某种程度上参与了K'Mudku事件的最后阶段。但是，这种构造框架概念仍然需要更多的地质和地球物理研究。因此，这些新闻数据应促使该地区恢复地质研究，并就亚马逊北部克拉通中东部至斯腾时期的构造演化和A型花岗岩生产进行辩论。

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