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首页> 外文期刊>Brazilian Journal of Geology >Lithogeochemistry and geochronology of the subalkaline felsic plutonism that marks the end of the Paleoproterozoic orogeny in the Salvador-Esplanada belt, S?o Francisco craton (Salvador, state of Bahia, Brazil)
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Lithogeochemistry and geochronology of the subalkaline felsic plutonism that marks the end of the Paleoproterozoic orogeny in the Salvador-Esplanada belt, S?o Francisco craton (Salvador, state of Bahia, Brazil)

机译：盐碱岩长岩质岩性的岩石地球化学和年代学标志着萨尔瓦多-埃斯普兰达带的古元古代造山运动的终结，圣弗朗西斯科克拉通（萨尔瓦多，巴西巴伊亚州）

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Studies conducted over the last decade concerning the rocks that underlie the municipality of Salvador have shown a complex geological history with a great diversity of medium- to high-grade metamorphic lithotypes, deformed in several phases and frequently cut by tabular mafic dykes and irregular granitic bodies. The latter, which were the subject of this study, frequently outcrop along the coastline of Salvador and are classified petrographically as monzo-syenogranites. They are classified as subalkaline and peraluminous according to their geochemical data, and stand out for being enriched in light rare earth elements and having a strong negative Europium (Eu) anomaly. These rocks are produced from anatectic melts or through the interaction of mantle-derived magmas with crustal materials. The negative values of εNd(t) (-6.08) corroborate with the crustal character and in the diagrams of tectonic ambience, they are plotted in the field of post-tectonic granites. The Sm-Nd model age (TDM) around 2.9 Ga indicates a neoarchean source for these lithotypes, whereas their U-Pb zircon age (LA-ICPMS) of 2,064 ± 36 Ma is similar to the U-Pb (SHRIMP) and Pb-Pb (evaporation) ages for late-tectonic granites of the Itabuna-Cura?á-Salvador belt. Considering the results of recent studies in the area of Salvador, the monzo-syenogranites can be interpreted as late-tectonic intrusions, since they are affected by dextral shear zones correlated with the last stage of deformation registered in the granulites of Salvador.
机译：在过去的十年中，对萨尔瓦多市内的岩石进行的研究表明，地质历史复杂，具有中到高级变质岩性的多种多样，在几个阶段中变形，并且经常被板状基性岩脉和不规则的花岗岩体切割。 。后者是本研究的主题，经常在萨尔瓦多的海岸线上露头，并在岩相学上被归类为门多-正长花岗岩。根据它们的地球化学数据，它们被分为亚碱性和高铝的，并且因富含轻稀土元素并且具有很强的负Euro（Eu）异常而脱颖而出。这些岩石是由南极熔融物或地幔衍生岩浆与地壳物质的相互作用产生的。 εNd（t）（-6.08）的负值与地壳特征相吻合，在构造环境图中，它们绘制在后构造花岗岩领域。大约2.9 Ga的Sm-Nd模型年龄（TDM）指示出这些岩性的新陈代谢来源，而它们的U-Pb锆石年龄（LA-ICPMS）为2,064±36 Ma类似于U-Pb（SHRIMP）和Pb- Itabuna-Cura？á-Salvador带晚期构造花岗岩的Pb（蒸发）年龄。考虑到萨尔瓦多地区最近的研究结果，单晶型片岩可以解释为晚构造侵入，因为它们受到与萨尔瓦多颗粒中记录的变形的最后阶段相关的右旋剪切带的影响。

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