Cretaceous volcanic rocks of the South Tethyan suture zone, Pakistan: implications for the Réunion hotspot and Deccan Traps |
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Authors: | JJ Mahoney RA DuncanW Khan E GnosGR McCormick |
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Institution: | a School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, HI 96822, USA b College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA c Geological Survey of Pakistan, Quetta, Pakistan d Mineralogisch-Petrographisches Institut, University of Bern, 3012 Bern, Switzerland e Department of Geology, University of Iowa, Iowa City, IA 52242, USA |
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Abstract: | The location, ages, and geochemical characteristics of marine volcanic rocks preserved in the South Tethyan suture zone of Pakistan suggest that the Réunion hotspot was active off northwestern Greater India well before the emplacement, far to the south, of the Deccan flood basalts, the great bulk of which were erupted at 65-66 Ma and are widely believed to be associated with the hotspot’s plume-head phase. Most of the suture zone samples have Nd-Pb-Sr isotopic ratios (e.g. age-corrected ?Nd(t)=+3.0 to +4.6) close to those expected for modern-type Réunion source mantle in the Late Cretaceous, and their incompatible element patterns resemble those of recent Réunion shield lavas. 40Ar-39Ar incremental heating yields ages of 73.4-72.0 Ma. Nevertheless, unless even older ages are discovered among the suture zone rocks, a pre-Deccan marine phase of Réunion hotspot activity on the Tethyan side of Greater India can be accommodated within the framework of the plume-head model. |
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Keywords: | hot spots flood basalts Deccan Traps Reunion Tethys |
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