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Very long-term stability of passive margin escarpment constrained by 40 Ar-39 Ar dating of K-Mn oxides
Abstract : The post-rift denudation history of high-elevation divergent continental
margins is central to deciphering source-to-sink systems across
such margins and to unraveling their topographic evolution. We performed
40Ar-39Ar dating of supergene K-Mn oxides from supergene
manganese ore deposits in order to constrain the age of in situ formed
laterites on both the lowland and highland sides of the Western Ghats
Escarpment of Peninsular India. Documentation of laterites as old
as 53 Ma on the highland and 47 Ma at the foot of the escarpment
shows that the escarpment stabilized before 47 Ma (possibly 60 Ma).
The topographic setting of the dated weathering mantles also constrains
denudation of the lowland and the highland since ca. 50 Ma
to maximums of 5 m/m.y. and 15 m/m.y., respectively. Our results
challenge denudation rates derived from apatite fission track thermochronology
by documenting the topography and relief longevity
of the southwest Indian margin and its hinterland. The results preclude
large-magnitude uplift of Peninsular India after the Eocene,
and more generally argue against late Neogene uplift and topographic
rejuvenation of continental shields.
Cited literature [1 references]
https://hal.ird.fr/ird-01419633
Contributor : Anicet Beauvais <>
Submitted on : Monday, December 19, 2016 - 5:06:03 PM
Last modification on : Friday, January 8, 2021 - 10:12:12 AM
Long-term archiving on: : Monday, March 20, 2017 - 4:34:27 PM
Contributor : Anicet Beauvais <>
Submitted on : Monday, December 19, 2016 - 5:06:03 PM
Last modification on : Friday, January 8, 2021 - 10:12:12 AM
Long-term archiving on: : Monday, March 20, 2017 - 4:34:27 PM
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