--> ABSTRACT: Sequence Stratigraphy in Eolian Systems, by Christopher S. Swezey; #90906(2001)

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Christopher S. Swezey1

(1) U. S. Geological Survey, Reston, VA

ABSTRACT: Sequence Stratigraphy in Eolian Systems

Sediment may become available for construction of eolian bedforms when there is a change from relatively humid to relatively arid conditions. For example, sand that is stored as a fluvial deposit may be reworked into an eolian deposit when there is a relative fall in sea level or water table, a decrease in precipitation, a reduction in abundance of vegetation, or an increase in wind strength. As arid conditions persist, the eolian sediment supply becomes depleted and wind scours the substrate. This situation will form a regressive surface (or sequence boundary). In the rock record, such a surface will appear as an unconformity. Regressive surfaces in eolian systems are associated with depletion of an eolian sediment source. They are initiated in an upwind area and they extend progressively downwind. The surfaces are deflationary, although deflation may eventually cease if the surface either encounters a water table or produces a lag of coarse sediment that prevents the underlying sediment from additional deflation. In contrast, transgressive surfaces are associated with changes from relatively arid to relatively humid conditions. They can form by a relative rise in sea level or water table, an increase in precipitation, an increase in abundance of vegetation, or a decrease in wind strength. Transgressive surfaces are associated with a restriction of eolian sediment mobility. They are characterized by non-eolian sediments that bury the eolian sediment and/or by pedogenic features that stabilize the eolian sediment.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado