Universität zu Köln

Binnie, S. A., Reicherter, K. R., Victor, P., Gonzalez, G., Binnie, A., Niemann, K., Stuart, F. M., Lenting, C., Heinze, S., Freeman, S. P. H. T. and Dunai, T. J. (2020). The origins and implications of paleochannels in hyperarid, tectonically active regions: The northern Atacama Desert, Chile. Glob. Planet. Change, 185. AMSTERDAM: ELSEVIER. ISSN 1872-6364

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Abstract

Preserved remnants of fluvial activity in deserts constitute evidence for changing boundary conditions. The Atacama Desert of northern Chile is the global end-member for aridity, so the history of relict stream networks in this region is a record of how landscapes develop under extreme conditions. On Pampa de Tana in northern Chile (19.4 degrees S), a series of channel forms that are presently inactive but in the past flowed westward are incised into the surface of a fault bounded, topographically elevated portion of the El Diablo Formation, a regionally extensive, relict pediment. We measure cosmic-ray produced Be-10, Al-26 and Ne-21 in fluvial deposits to date the timing of abandonment of three channels and couple this with topographic profile information from a SPOT-6 derived, 2 m resolution digital elevation model. We find two of the channels were abandoned approximately > 5.6 Myr and 2.0 Myr ago. One channel is still capable of flow and has ages suggesting it was fluvially active within the last few hundred thousand years. Using the paleochannel ages measured here and published ages for the end of aggradation of the El Diablo Formation we estimate the rates of fluvial channel incision before channel abandonment, and uplift rates on the faults after channel abandonment. Maximum uplift rates of similar to 12 m/Myr over the last 2 Myr are found. In general, while rates of uplift are relatively low they are several-fold more rapid than the rates of fluvial incision prior to channel abandonment. This implies that westward channel flow was interrupted by uplift of topography above a blind NW-SE striking reverse fault that affects the Central Depression, an alluvial forearc basin. We consider also that shrinkage of the upstream catchment area by stream capture, promoted via headward erosion and lateral expansion of adjacent canyons (quebradas) could be a factor in the abandonment of the channels on Pampa de Tana. Our results highlight the polygenetic nature of this landscape and show that relatively minor amounts of fault displacement in hyperarid regions can have implications for stream network evolution. Even subtle topographic uplift upstream should be taken into account when fluvial deposits are used as proxies for long-term environmental conditions.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Binnie, S. A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Reicherter, K. R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Victor, P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Gonzalez, G. UNSPECIFIED UNSPECIFIED UNSPECIFIED Binnie, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Niemann, K. UNSPECIFIED UNSPECIFIED UNSPECIFIED Stuart, F. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Lenting, C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Heinze, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Freeman, S. P. H. T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Dunai, T. J. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-351640
DOI:	10.1016/j.gloplacha.2019.103083
Journal or Publication Title:	Glob. Planet. Change
Volume:	185
Date:	2020
Publisher:	ELSEVIER
Place of Publication:	AMSTERDAM
ISSN:	1872-6364
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language WIND-GAP FORMATION; LANDSCAPE EVOLUTION; DENUDATION RATES; COSMOGENIC NE-21; EXPOSURE AGES; LATE MIOCENE; HALF-LIFE; CLIMATE; BE-10; NEOGENE Multiple languages Geography, Physical; Geosciences, Multidisciplinary Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/35164