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Late Quaternary kinematics of the Pallatanga strike-slip fault (Central Ecuador) from topographic measurements of displaced morphological features

Winter, Thierry and Avouac, Jean-Philippe and Lavenu, Alain (1993) Late Quaternary kinematics of the Pallatanga strike-slip fault (Central Ecuador) from topographic measurements of displaced morphological features. Geophysical Journal International, 115 (3). pp. 905-920. ISSN 0956-540X. http://resolver.caltech.edu/CaltechAUTHORS:20120910-151739673

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Abstract

The northeast-trending Pallatanga right-lateral strike-slip fault runs across the Western Cordillera connecting N50°E-N70°E trending normal faults in the Gulf of Guayaquil with N-S reverse faults in the Interandean Depression. Over most of its length, the fault trace has been partly obscured by erosional processes and can be inferred in the topography only at the large scale. Only the northern fault segment, which follows the upper Rio Pangor valley at elevations above 3600 m, is prominent in the morphology. Valleys and ridges cut and offset by the fault provide an outstanding record of right-lateral cumulative fault displacement. The fault geometry and kinematics of this particular fault segment can be determined from detailed topographic levellings. The fault strikes N30°E and dips 75° to the NW. Depending on their size and nature, transverse morphological features such as tributaries of the Rio Pangor and intervening ridges, reveal right-lateral offsets which cluster around 27 ± 11m, 41.5 ± 4 m, 590 ± 65 m and 960 ± 70 m. The slip vector deduced from the short-term offsets shows a slight reverse component with a pitch of about 11.5° SW. The 41.5 ± 4 m displacements are assumed to be coeval with the last glacial termination, yielding a mean Holocene slip-rate of 2.9- 4.6 mm yr^(−1). Assuming a uniform slip rate on the fault in the long term, the 27 m offset appears to correlate with an identified middle Holocene morphoclimatic event, and the long term offsets of 590 m and 960 m coincide with the glacial terminations at the beginning of the last two interglacial periods.


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http://dx.doi.org/10.1111/j.1365-246X.1993.tb01500.x DOIUNSPECIFIED
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-246X.1993.tb01500.x/abstractPublisherUNSPECIFIED
Additional Information:© 1993 RAS. Accepted 1993 May 4. Received 1993 May 4; in original form 1993 January 14. Article first published online: 2 Apr. 2007. We thank Peter Molnar and Bob Yeats for constructive and thorough reviews. This study has benefited from fruitful discussions with Gilles Peltzer, Yves Gaudemer, Bertrand Meyer, Rolando Armijo and Paul Tapponnier. Special thanks are due to Guy Aveline for the illustration. This study was supported by IFEA and ORSTOM (Contract IPGH-EPN-CLIRSEN-ORSTOM-IFEA in Ecuador).
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Record Number:CaltechAUTHORS:20120910-151739673
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20120910-151739673
Official Citation:Winter, T., Avouac, J.-P. and Lavenu, A. (1993), Late Quaternary kinematics of the Pallatanga strike-slip fault (Central Ecuador) from topographic measurements of displaced morphological features. Geophysical Journal International, 115: 905–920. doi: 10.1111/j.1365-246X.1993.tb01500.x
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ID Code:33978
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:10 Sep 2012 22:29
Last Modified:28 Aug 2014 18:51

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