Magmatic ocean-continent transitions
Type | Article | ||||||||||||||||
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Date | 2019-06 | ||||||||||||||||
Language | English | ||||||||||||||||
Author(s) | Guan Huixin1, 2, Geoffroy Laurent1, 2, Gernigon Laurent3, Chauvet Francois1, 2, Grigne Cecile1, 2, Werner Philippe4 | ||||||||||||||||
Affiliation(s) | 1 : Univ Bretagne Occidentale, F-29238 Brest, France. 2 : CNRS, UMR 6538, Lab Domains Ocean, F-29280 Plouzane, France. 3 : Geol Survey Norway NGU, Trondheim, Norway. 4 : Univ Strasbourg, F-67089 Strasbourg, France. |
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Source | Marine And Petroleum Geology (0264-8172) (Elsevier Sci Ltd), 2019-06 , Vol. 104 , P. 438-450 | ||||||||||||||||
DOI | 10.1016/j.marpetgeo.2019.04.003 | ||||||||||||||||
WOS© Times Cited | 23 | ||||||||||||||||
Keyword(s) | Volcanic passive margins, SDRs, Polyphased lithospheric, Extension | ||||||||||||||||
Abstract | Continental extension may, or may not, be coeval with significant mantle melting, leading to the formation of distinct types of passive margins (respectively magma-poor or volcanic), with distinct crustal structures. Especially in inter-cratonic mobile areas, magmatic breakup and development of volcanic passive margins (VPMs) may postdate the early development of a non-magmatic continental rift system. The time-span between the amagmatic and the magmatic systems may be relatively short or, conversely, long (tens of millions years). Such evolution is often associated with a significant apparent asymmetry in the wideness of conjugate VPMs. In this paper, we attempt to re-interpret the structure of three paired VPMs which developed close to, but separately from, a previous amagmatic aborted rift system. Due to opposite dips in major crustal detachment faults accommodating extension from sedimentary to volcanic stages, those composite margins tend to individualize a fault-dissected continental block (here designed as L-Block) along one of the conjugate margins. In addition to the amount and distribution of amagmatic extension, the time-span between amagmatic and magmatic extension exerts a major structural and rheological control on the final structure of the ocean-continent transitions, The finite margin geometry may be erroneously interpreted as resulting from a continuous process from hyper extension to the final magmatic breakup. However, the early syn-sedimentary extension appears, in many cases, to be low-rate or episodic. Consequently, the VPM final breakup of the lithosphere may shift away from the original amagmatic stretched area to the rifted margin. |
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