OceanRep
Heat flow over the descending Nazca plate in Central Chile, 32° to 41°S: evidence from the ODP leg 202 and the occurrence of natural gas hydrates.
Grevemeyer, Ingo , Diaz-Naveas, J. L., Ranero, C. R. and Villinger, H. and Ocean Drilling Program Leg 202 Scientific Party (2003) Heat flow over the descending Nazca plate in Central Chile, 32° to 41°S: evidence from the ODP leg 202 and the occurrence of natural gas hydrates. Earth and Planetary Science Letters, 213 (3-4). pp. 285-298. DOI 10.1016/S0012-821X(03)00303-0.
Text
1-s2.0-S0012821X03003030-main.pdf - Published Version Restricted to Registered users only Download (901kB) | Contact |
Abstract
ottom simulating reflectors (BSRs) were detected in multichannel seismic reflection data acquired in the vicinity of Isla Mocha across the southern Chile margin and near 33°S. Geothermal gradients were determined from the depth of the BSR that is interpreted to mark the thermally controlled base of a gas hydrate layer. Ground truth for the assessment and additional thermal constraints were provided by downhole measurements obtained during Ocean Drilling Program (ODP) Leg 202 in Site 1233 at 41°S and Sites 1234 and 1235 near 36°S. Both BSR-derived data and downhole temperatures were used to calculate heat flow anomalies and provide new constraints on the thermal regime of the continental slope and downgoing slab in Chile between 32°S and 41°S. Downhole chemical logs of Th, U, and K from Site 859 of ODP Leg 141 have been used to assess the radiogenic heat production in the margin wedge. Heat production is low (∼0.8 μW/m3). However, knowledge of this reduces the errors of estimating the contribution from frictional heating along the subduction thrust fault. With respect to the Eocene age of the incoming oceanic lithosphere, heat flow appears to decrease landward of the deformation front as expected due to the advective transport of heat into the subduction zone by the downgoing slab. Calculations of conductive fore-arc heat flow show that the modelled seafloor heat flow agrees with the measured heat flow only if there is negligible frictional heating. At 33°S, temperatures in the fault zone reach 100°C approximately 60 km landward of the deformation front and are coincident with the onset of earthquake activity and hence mark the up-dip limit of the seismogenic zone. The up-dip limit shifts seaward going to the south, reflecting the progressive southward decrease of lithospheric age of the subducting plate.
Document Type: | Article |
---|---|
Keywords: | Ocean Drilling Program; gas hydrates; heat flow; thermal state; shear heating; radioactive heat generation |
Research affiliation: | OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics |
Refereed: | Yes |
Open Access Journal?: | No |
Publisher: | Elsevier |
Projects: | ODP |
Date Deposited: | 18 Feb 2008 17:26 |
Last Modified: | 15 Nov 2016 10:59 |
URI: | https://oceanrep.geomar.de/id/eprint/2844 |
Actions (login required)
View Item |
Copyright 2023 | GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel | All rights reserved
Questions, comments and suggestions regarding the GEOMAR repository are welcomed
at bibliotheksleitung@geomar.de !