Stratigraphy, age and provenance of the metavolcano-sedimentary succession of the Gurupi Belt, northern Brazil: Implications for the tectonic setting and Rhyacian geodynamic evolution

IF 3.2 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Precambrian Research Pub Date : 2025-05-28 DOI:10.1016/j.precamres.2025.107815

Antonia Railine da Costa Silva , Evandro L. Klein , Jean-Michel Lafon

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Abstract

The Gurupi Belt, northern Brazil, represents a Proterozoic belt, whose rocks were mainly formed during the orogenic events that occurred in the Rhyacian and Ediacaran-Cambrian periods. The Paleoproterozoic lithological association includes the metavolcano-sedimentary Chega Tudo Formation, the main host of gold deposits in the belt, batholiths and stocks of subduction-related and collisional granitoids, orogenic basins, and other minor units. To advance on the understanding of the depositional and tectonic settings of the metavolcano-sedimentary sequence, we investigated outcrop and drill core samples from the NW sector of the belt, which revealed rocks well-preserved from the effects of deformation and metamorphism, which affected the belt. Nine lithofacies were distinguished for the sequence and grouped into pyroclastic, volcaniclastic, epiclastic and volcanic-subvolcanic associations, which indicates a subaqueous depositional environment sedimentation and andesitic-dacitic volcanism interaction. The U-Pb ages in zircon from volcanic, volcaniclastic and epiclastic (detrital zircon) show that the Chega Tudo Formation was deposited between 2.20 and 2.14 Ga, with at least three episodes of volcanic activity at 2.20, 2.18 and 2.16 Ga. A back-arc setting, formed during early stages of the orogeny is indicated. Detrital zircons suggest that only arc-related sources (2.22 to 2.24 Ga) were involved in the early stages of sedimentation (accretionary arc), possibly derived from the São Luís cratonic fragment, switching to older populations (∼2.3 Ga) in the latter stages (collisional arc), probably from the basement of the West African Craton or the Bacajá Domain of the Amazonian Craton. Two subunits are proposed: a Lower Unit, with immature metapelitic and mafic-felsic volcanic rocks, associated to deep waters in the back-arc basin initiation stage; and, an Upper Unit, mainly formed by volcaniclastic rocks and andesite-dacite, formed later, under shallow waters.

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巴西北部古鲁皮带变质火山-沉积演替的地层学、年龄和物源：构造背景和流纹期地球动力学演化的意义

古鲁皮带位于巴西北部，是一个元古代带，其岩石主要形成于古拉纪和埃迪卡拉纪-寒武纪造山活动期间。古元古代岩性组合包括变质火山-沉积车嘎图都组、带内金矿床的主要宿主、俯冲相关和碰撞花岗岩岩基和岩基群、造山盆地及其他小单元。为了进一步认识变质火山-沉积序列的沉积和构造环境，我们对该带NW段的露头和岩心样品进行了研究，发现受变形和变质作用影响的岩石保存完好。在层序上划分出9个岩相，分为火山碎屑岩相、火山碎屑岩相、火山碎屑岩相和火山-次火山相组合，表明其沉积环境为水下沉积和安山岩-英安质火山相互作用。火山锆石、火山碎屑锆石和碎屑锆石的U-Pb年龄表明，车加图都组沉积于2.20 ~ 2.14 Ga之间，在2.20、2.18和2.16 Ga至少有3期火山活动。在早期造山运动中形成了弧后环境。碎屑锆石表明，沉积早期（增生弧）只涉及与弧相关的源（2.22 ~ 2.24 Ga），可能来自于 o Luís克拉通碎屑，在后期（碰撞弧）转换为更古老的源（~ 2.3 Ga），可能来自于西非克拉通的基底或亚马逊河克拉通的bacaja 域。在弧后盆地形成阶段，形成了两个亚单元：下亚单元，由未成熟的变质岩和镁质-长英质火山岩组成，与深水有关；上部单元，主要由较晚形成的火山碎屑岩和安山英安岩组成。

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来源期刊

Precambrian Research 地学-地球科学综合

CiteScore

7.20

自引率

28.90%

发文量

325

审稿时长

12 months

期刊介绍： Precambrian Research publishes studies on all aspects of the early stages of the composition, structure and evolution of the Earth and its planetary neighbours. With a focus on process-oriented and comparative studies, it covers, but is not restricted to, subjects such as: (1) Chemical, biological, biochemical and cosmochemical evolution; the origin of life; the evolution of the oceans and atmosphere; the early fossil record; palaeobiology; (2) Geochronology and isotope and elemental geochemistry; (3) Precambrian mineral deposits; (4) Geophysical aspects of the early Earth and Precambrian terrains; (5) Nature, formation and evolution of the Precambrian lithosphere and mantle including magmatic, depositional, metamorphic and tectonic processes. In addition, the editors particularly welcome integrated process-oriented studies that involve a combination of the above fields and comparative studies that demonstrate the effect of Precambrian evolution on Phanerozoic earth system processes. Regional and localised studies of Precambrian phenomena are considered appropriate only when the detail and quality allow illustration of a wider process, or when significant gaps in basic knowledge of a particular area can be filled.