4.5 Article

A suture related accretionary wedge in the Gondwana assembly: Insights from serpentinites in the Hoggar shield, Algeria

期刊

PRECAMBRIAN RESEARCH
卷 369, 期 -, 页码 -

出版社

ELSEVIER
DOI: 10.1016/j.precamres.2021.106505

关键词

Serpentinite; Mantle wedge; Neoproterozoic; Panafrican belt; West Gondwana orogen; Suture

资金

  1. FP7 IRSES-MEDYNA project [PIRSES-GA-2013-612572]
  2. Algerian ministry of Higher Education and Scientific Research
  3. Faculty of Earth Sciences, USTHB, Algeria [PRFU E04N01UN160420220007]

向作者/读者索取更多资源

This study investigates the assembly of the West Gondwana supercontinent and provides evidence for the formation of the Hoggar shield. Petro-geochemical and geochronological analyses of serpentinite lenses and metasomatic chloritite reveal the formation mechanisms and ages of these rocks. The findings support the existence of a significant suture zone, contributing to our understanding of the evolution of the Gondwana supercontinent.
The assembly of West Gondwana supercontinent involved several complex processes that led to the formation of the Hoggar shield during the Panafrican-Brasiliano event. We present the first petro-geochemical, geochronological and field data of serpentinite lenses exposed along the In-Tedeini domain, within deformed talc-schist and magmatic-sedimentary formations. The serpentinites preserved the main characteristics of their parent peridotites (Al/Si: 0.004-0.03; Mg/Si: 1.14-1.62; Al2O3: 0.15-1.37 wt%; Mg#: 85.3-94; Ti: 9.34-120 ppm; Nb: 0.007-0.46 ppm), attesting to a highly depleted mantle wedge protolith involved in a subduction zone. This is in agreement with the high Cr# (0.55-0.6), low to moderate Mg# (0.36-0.65) and low TiO(2 )contents (< 0.1 wt%) of their constitutive Cr-spinels. Geochemical modelling suggest that both the North and South In-Tedeini serpentinite units have experienced intense and similar fluid-induced dynamic melting episodes. The evolution of these two units has diverged, with the Southern In-Tedeini unit being refertilized by a small volume of island-arc basaltic melts generated in the mantle wedge. Serpentinization of these rocks probably occurred under static conditions at high temperature corresponding essentially to amphibolite-facies conditions. Field relations suggest that the exhumation of the massive serpentinites occurred along major sinistral shear zones steeply dipping eastward, assisted by talc-schists that highly localized transpressive deformation. First U-Pb zircon ages obtained from a metasomatic chloritite in North In-Tedeini serpentinites; they may have recorded the age (770 +/- 5 Ma) of the subduction related Panafrican island arcs and the emplacement (631 +/- 10 Ma) of In-Tedeini serpentinites within the crust; or they may rather correspond to the serpentinization events endured by the rocks. All together, the reported results support the presence of a major suture zone, oriented NNW-SSE. This suture is outlined by mantle serpentinite lenses exhumed in a collisional accretionary wedge, which connects the western and the central Hoggar, following a Panafrican east-dipping subduction. This tectonic system would have contributed to the closure of the Goias-Pharusian ocean.

作者

我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。

评论

主要评分

4.5
评分不足

次要评分

新颖性
-
重要性
-
科学严谨性
-
评价这篇论文

推荐

暂无数据
暂无数据