ISSN:
1365-3121
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Geosciences
Notes:
The Neogene carbonate stratigraphy of five sites drilled on Ontong Java Plateau during Leg 130 reveals a number of patterns which are unexpected, and which we refer to as loss paradox, equatorial insensitivity, and climate paradox. They denote the following unresolved questions.〈list xml:id="l1" style="custom"〉1The loss of carbonate at depth (as derived from differences in accumulation rates) is much greater than suggested by the change in carbonate percentages (calculated under the assumption that carbonate dissolution is the cause of loss). This indicates an important role for redeposition processes, such as winnowing (bottom currents), sifting (resuspension and catabatic flow) and episodic sloughing or solifluction (presumably stimulated by earthquakes).2Accumulation rates are not markedly increased at the time a site crosses the equator. There are several possible reasons. Equatorial upwelling may be unimportant in controlling sedimentation rates this far in the western Pacific, or its output may be spread over a considerable distance from the equator. Alternatively, increased supply below the equator is compensated for by increased removal (e.g. from resuspension by bioturbation, combined with catabatic flow). It is conceivable that errors in the timescale could also produce the effect seen.3There is an overall tendency for agreement between the stratigraphic patterns of carbonate content and of accumulation rates, but neither pattern is readily explained by reference to changes in climate (represented by benthic δ18O) or in sea-level (as derived from sequence stratigraphy).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-3121.1994.tb00896.x
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