Abstract

Holocene fluvial sands derived from the same type of crystalline parent rocks in humid-temperate and arid/semi-arid climates have distinct compositions. For a particular climate and parent rock, the similarity in composition of the fluvial sands and the sand-size fraction of soils collected from the associated interfluves indicates that climatically controlled weathering of a specific parent rock type is a primary control of sand composition. Published estimates of the magnitude of destruction of lithic fragments and feldspars associated with stream transport and deposition in a beach/coastal dune environment permit the simulation of quantitative approximations of compositional maturation of sand. For transport distances of <75 km the simulated maturation does not significantly modify the distinctive climatic imprints on composition. However, simulated maturation due to deposition in beach/coastal dune environment effectively destroys the climatic imprint. Although marine processes are highly capable of mechanically destroying lithic fragments and feldspar, our study suggests that large-scale production of first-cycle quartz arenites in such an environment is not probable. Only a rare, unique combination of extreme conditions of climate (tropical), relief (low), and sedimentation rate (slow) can give rise to first-cycle quartz arenites. Therefore we conclude that the bulk of ancient quartz arenite is multicycle in origin.

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