Generation of talc in the mantle wedge and its role in subduction dynamics in central Mexico
Abstract
Geophysical evidence shows the presence of low-seismic velocity material at the surface of slabs in subduction zones. In the central Mexican subduction zone this appears as a thin (∼4 km) low-velocity zone that absorbs nearly all of the strain. The P-to-S velocity ratio as a function of S wave velocity distinguishes among the various candidate hydrous (low-strength) minerals; the thin layer in the flat-slab region is most consistent with a layer showing enrichment in talc overlying normal MORB-like gabbro. Based on available thermodynamic data for equilibria for talc, its generation at the trench is nearly impossible, and hence we propose it originates from the mantle wedge during the slab flattening process coupled with trench rollback. The evolution of this low-strength zone has important implications for the dynamics of the slab-flattening process as well as the geochemistry of the mantle wedge and arc in central Mexico.
Additional Information
© 2013 Elsevier B.V. Received 13 August 2013; Received in revised form 3 October 2013; Accepted 4 October 2013; Available online 27 October 2013. Editor: P. Shearer This work was funded by the Korea Meteorological Administration Research and Development Program under Grant CATER-2013-8010. This study was also supported by the Gordon and Betty Moore Foundation through the Tectonics Observatory at California Institute of Technology (Contribution number 223) and NSF award EAR 0609707. We used Excel Worksheets and Macros from Hacker and Abers (2004) for calculating seismic speeds. We thank Xyoli Perez-Campos, Arturo Iglesias, and others at the Universidad Nacional Autonoma de Mexico for deploying and maintaining the MASE line. We also thank Joann Stock and Michael Gurnis from California Institute of Technology for discussions. Finally, we thank Editor Peter Shearer, Pascal Audet, and one anonymous reviewer for helpful comments which improved the manuscript.Additional details
- Eprint ID
- 43400
- DOI
- 10.1016/j.epsl.2013.10.006
- Resolver ID
- CaltechAUTHORS:20140116-090617911
- CATER-2013-8010
- Korea Meteorological Administration Research and Development Program
- Gordon and Betty Moore Foundation
- Caltech Tectonics Observatory
- EAR 0609707
- NSF
- Created
-
2014-01-16Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field
- Caltech groups
- Caltech Tectonics Observatory, Seismological Laboratory, Division of Geological and Planetary Sciences
- Other Numbering System Name
- Caltech Tectonics Observatory
- Other Numbering System Identifier
- 223