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首页> 外文期刊>Brazilian Journal of Geology >A preserved early Ediacaran magmatic arc at the northernmost portion of the Transversal Zone central subprovince of the Borborema Province, Northeastern South America
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A preserved early Ediacaran magmatic arc at the northernmost portion of the Transversal Zone central subprovince of the Borborema Province, Northeastern South America

机译：在南美洲东北部Borborema省中部横穿带中部最北端保留的早期Ediacaran岩浆弧

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Magmatic arcs are an essential part of crust-forming events in planet Earth evolution. The aim of this work was to describe an early Ediacaran magmatic arc (ca. 635-580 Ma) exposed in the northernmost portion of the Transversal Zone, central subprovince of Borborema Province, northeast Brazil. Our research took advantage of several syntheses by different authors, including theses and dissertations, carried out on magmatic rocks of the study area for the last 30 years. The ca. 750 km long and up to 140 km wide arc, trending ENE-WSW, is preserved to the south of the Patos Lineament, between 35?o15' and 42?o30'W and 7?o15' and 8?oS. About 90 different stocks and batholiths of I-type granitic rocks were mapped along this orogenic zone, preferentially intruding low-grade schists of the Cryogenian-Ediacaran Pianc?3-Alto Br?-gida (SPAB) belt. Three igneous supersuites are recognized: a) epidote-bearing granodiorites and tonalites ("Concei?§?￡o" type); b) high-K calc-alkaline granites ("Itaporanga" type); c) biotite granodiorites of trondhjemite affinity ("Serrita" type). A fourth group of peralkalic and shoshonitic rocks occurs to the south of the previous ones, reflecting special tectonic conditions. NNE-SSW trending Paleoproterozoic fold belts, surrounding Archean nuclei, characterize the continental part of the northern lower plate. The oceanic fraction of this lower plate was recycled by subduction and scarce remnants of which may be seen either within the enclosing low-grade schists or as xenoliths within the arc intrusions. The upper continental plate presents WSW-ENE structural trends and is composed of Neoproterozoic fold belts and Paleoproterozoic reworked basement inliers. Available data bear clear evidence of an Ediacaran magmatic arc built at the northern portion of the Transversal Zone in the Borborema Province, northeast Brazil.
机译：岩浆弧是地球演化过程中地壳形成事件的重要组成部分。这项工作的目的是描述一个早期的Ediacaran岩浆弧（约635-580 Ma），它暴露于巴西东北部Borborema省中部横穿带的最北部。我们的研究利用了不同作者在过去30年中在研究区岩浆岩上进行的几项综合研究，包括论文和论文。该ca。帕诺斯线（Patos Lineament）的南部保存着长750公里，宽140公里的弧线，趋势为ENE-WSW，介于35？o15'和42？o30'W之间以及7？o15'和8？oS之间。沿该造山带绘制了约90种I型花岗岩的储层和岩基，优先侵入了深冷-爱迪亚卡拉·潘安奇？3-阿尔托？布鲁-吉达（SPAB）带的低品位片岩。识别出三个火成岩的超级套装：a）带有附子的花岗闪长岩和孔雀石（“ Concei？§？￡ o”类型）; b）高钾钙碱性花岗岩（“ Itaporanga”型）; c）变白云母亲和力（“ Serrita”型）的黑云母花岗闪长岩。第四组过碱性和斜生岩石出现在前者的南部，反映了特殊的构造条件。 NNE-SSW系古生界核周围的古元古代褶皱带，是北部下部板块的大陆部分。该下部板块的海相部分通过俯冲来再循环，其稀少的残余物可能在封闭的低级片岩中或在弧侵入体中被视为异岩。上大陆板块显示了WSW-ENE的构造趋势，由新元古代褶皱带和古元古代返修的地下室组成。现有数据清楚地表明，在巴西东北部Borborema省横向带的北部建造了一个Ediacaran岩浆弧。

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