Universität zu Köln

Hoffmann, J., Bahr, A., Voigt, S., Schoenfeld, J., Nuernberg, D. and Rethemeyer, J. (2014). Disentangling abrupt deglacial hydrological changes in northern South America: Insolation versus oceanic forcing. Geology, 42 (7). S. 579 - 583. BOULDER: GEOLOGICAL SOC AMER, INC. ISSN 1943-2682

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Abstract

Paleoenvironmental studies and climate models demonstrate that fluvial runoff and moisture availability in the Caribbean hinterland react very sensitively to climatic variations. Late Pleistocene and Holocene climate records document pronounced dry and wet periods over tropical South America mainly caused by shifts of the Intertropical Convergence Zone (ITCZ). However, forcing mechanisms for changes in the ITCZ position remain controversial. Here we present high-resolution foraminiferal Ba/Ca and delta O-18(seawater) records from a core located within the Orinoco River outflow documenting abrupt hydrological changes in the Orinoco catchment area during the deglacial and Holocene. Our data, obtained from the surface-dwelling foraminifera Globigerinoides ruber (pink), show an abrupt increase in Ba/Ca ratios in the early Holocene, starting similar to 600 yr after the end of the Younger Dryas (YD) cold interval at ca. 10.8 ka and suggesting a massive reorganization of moisture sources in northern South America. In contrast, the salinity dependent delta O-18(seawater) from the same samples shows a gradual decrease starting at the end of the YD. The offset of our Ba/Ca peak excludes meltwater release in conjunction with the northern Andean glacier retreat well before the end of the YD as a forcing mechanism. We suggest that the Ba/Ca record documents an abrupt increase in Ba-rich waters of a northern Andean source caused by the insolation-driven shift of the ITCZ and/or enhanced monsoon activity.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Hoffmann, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bahr, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Voigt, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Schoenfeld, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Nuernberg, D. UNSPECIFIED UNSPECIFIED UNSPECIFIED Rethemeyer, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-435289
DOI:	10.1130/G35562.1
Journal or Publication Title:	Geology
Volume:	42
Number:	7
Page Range:	S. 579 - 583
Date:	2014
Publisher:	GEOLOGICAL SOC AMER, INC
Place of Publication:	BOULDER
ISSN:	1943-2682
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language INTERTROPICAL CONVERGENCE ZONE; SEA-SURFACE TEMPERATURE; LAKE VALENCIA BASIN; TROPICAL ATLANTIC; THERMOHALINE CIRCULATION; FLUVIAL GEOCHEMISTRY; LAST DEGLACIATION; CLIMATE-CHANGE; ORINOCO; VARIABILITY Multiple languages Geology Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/43528