Journal articles
Pop-down tectonics, fluid channelling and ore deposits within ancient hot orogens
Abstract : Many Archaean and Paleoproterozoic deformation zones, often rich in ore resources, show particular structural patterns in particularmarked by regional vertical stretch. These zones are not restricted to greenstone-bearing Archaean domains that may have suffered gravity-driven sagduction of heavy supra-crustals, as extensively discussed since the last twenties. Structures are actually best explained by pop-down tectonics of upper-crustal unitswithin an underlyingweak crust submitted to horizontal regional shortening.Herewe present three complementary examples fromtwo Archaean greenstone belts (Abitibi sub-Province, Quebec, andMurchison belt, South Africa) and one greenstone-lacking Paleoproterozoic belt (Thompson belt,Manitoba). In the three examples, ore is concentrated along steeply dipping deformation zones, rich in syntectonic deposits and marked by substantial sub-vertical crustal stretch. On the other hand, the three regions show differences in age, in metamorphic grade (from sub-greenschist facies to upper amphibolite facies), in metal contents (gold, antimony, nickel), in metal sources, transfers and concentration histories. Our compared analysis emphasizes that pop-down tectonics associatedwith horizontal shortening of weak lithospheres may account for observed geometric patterns and provide a new and promising frame for the analysis of relationships between structural patterns and ore concentrations within old cratons.
Cited literature [2 references]
https://hal-insu.archives-ouvertes.fr/insu-00965100
Contributor : Isabelle Dubigeon <>
Submitted on : Monday, March 24, 2014 - 3:52:00 PM
Last modification on : Thursday, January 14, 2021 - 11:45:46 AM
Contributor : Isabelle Dubigeon <>
Submitted on : Monday, March 24, 2014 - 3:52:00 PM
Last modification on : Thursday, January 14, 2021 - 11:45:46 AM
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Gapaisetal.2014-HAL.pdf
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