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ABSTRACT: Titanium and iron concentration data from the anoxic Cariaco Basin, off the Venezuelan coast, can be used to infer variations in the hydrological cycle over northern South America during the past 14,000 years with subdecadal resolution. Following a dry Younger Dryas, a period of increased precipitation and riverine discharge occurred during the Holocene "thermal maximum." Since ~5400 years ago, a trend toward drier conditions is evident from the data, with high-amplitude fluctuations and precipitation minima during the time interval 3800 to 2800 years ago and during the "Little Ice Age." These regional changes in precipitation are best explained by shifts in the mean latitude of the Atlantic Intertropical Convergence Zone (ITCZ), potentially driven by Pacific-based climate variability. The Cariaco Basin record exhibits strong correlations with climate records from distant regions, including the high-latitude Northern Hemisphere, providing evidence for global teleconnections among regional climates. |
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| DATA: Download the Data from the WDC Paleo Archive. |
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Fig. 3. Bulk Ti content of Cariaco Basin sediments from ODP Site 1002 versus age, spanning (a) the last 14 ky (3-point running mean); (b) the last 5 ky (3-point running mean); and (c) the last 1.2 ky (raw data and 3-point running mean). Higher Ti content reflects greater terrigenous input from riverine runoff and is interpreted to indicate greater precipitation and a more northerly mean latitude of the ITCZ. |
| DISCUSSION: This high resolution record of titanium in a sediment core from the Cariaco Basin off the coast of Venezuela show the broad impact of the Younger Dryas and subsequent climate events. Titanium, which is a proxy for precipitation and land runoff, provides a record of the strong cooling and abrupt warming of the Younger Dryas (Figure 3a). Part b of the figure also reveals an increase in variability in the El Niño-Southern Oscillation system around 3,800 years ago, similar to results of Sandweiss et al. (1996) and Moy et al. (2002). Part c provides the finest temporal resolution and shows a generally warm period during the "Medieval Warm Period" and the stronger cooling during the Little Ice Age.
References cited:
Sandweiss, D.H., J.B. Richardson III, E.J. Reitz, H.B. Rollins, and K.A. Maasch. 1996. |
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Contact Us National Oceanic and Atmospheric Administration 10 May 2004
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