Wyniki wyszukiwania - BazTech

Ograniczanie wyników

1 Volumina Jurassica

1 2006

Znaleziono wyników: 1

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: Wingate

Sortuj według:

Ogranicz wyniki do:

Onset of erg sedimentation during the Early Jurassic on the Colorado Plateau, southwestern U.S.A.: climatic, eustatic and tectonic controls

Tanner L., Lucas S.

Volumina Jurassica

2006

Vol. 4, no. 1

106-106

Deposition of the Moenave and Wingate formations took place during the latest Triassic to Early Jurassic in a mosaic of terrestrial subenvironments including fluvial, lacustrine, and eolian. Fluvial-lacustrine processes dominated Moenave deposition, which included channelized flow in ephemeral to perennial streams, unconfined flow (sheetwash) in interchannel areas, ephemeral lakes (playas), and perennial lakes that were subject to episodic desiccation. The Moenave terminal floodplain, which was dotted by broad, shallow lakes, interfingered with the Wingate erg, where eolian processes dominated. The Moenave-Wingate outcrop belt exposes a north-south lithofacies gradient from distal (erg margin) to proximal (erg interior) as dominantly fluvial-lacustrine lithofacies in the north are replaced by mainly eolian dune and interdune deposits to the south, recording encroachment of the Wingate erg. The prevalence of ephemeral stream and eolian environments during deposition of these strata indicates a seasonally arid climate during the latest Triassic to earliest Jurassic. We see no sedimentologic evidence for significant climate change at the Triassic/Jurassic boundary, or at any time encompassed by this sedimentary succession. The growth and incursion of the Wingate erg into the Moenave fluvial system may have been driven by the availability of sediment in the up-wind source area, the coastal plain and coastline to which the Moenave streams delivered sediment. We interpret a eustatic signal as responsible for formation of this erg as long-term regression during the Rhaetian and continued Hettangian low-stand exposed a broader area of shallow marine sediments to eolian reworking. Preservation of the erg deposits may have been enhanced by tectonically controlled accommodation space as continental shortening led to crustal flexure during the Early Jurassic.