DEPOSITIONAL FRAMEWORK AND CONTROLS ON MIXED CARBONATE SILICICLASTIC GRAVITY FLOWS - PENNSYLVANIAN PERMIAN SHELF TO BASIN TRANSECT, SOUTH-WESTERN GREAT-BASIN, USA

Citation
Rp. Miller et Pl. Heller, DEPOSITIONAL FRAMEWORK AND CONTROLS ON MIXED CARBONATE SILICICLASTIC GRAVITY FLOWS - PENNSYLVANIAN PERMIAN SHELF TO BASIN TRANSECT, SOUTH-WESTERN GREAT-BASIN, USA, Sedimentology, 41(1), 1994, pp. 1-20
Citations number
55
Categorie Soggetti
Geology
Journal title
ISSN journal
00370746
Volume
41
Issue
1
Year of publication
1994
Pages
1 - 20
Database
ISI
SICI code
0037-0746(1994)41:1<1:DFACOM>2.0.ZU;2-H
Abstract
Mixed carbonate-siliciclastic sediment gravity flow deposits of Late P ennsylvanian to Early Permian age are exposed in the Death Valley - Ow ens Valley region of east-central California. The Mexican Spring unit constitutes the upper part of the Keeler Canyon Formation and is chara cterized by turbidites, debris flow deposits and megabreccias, all of mixed carbonate-siliciclastic composition. The mixed composition of th e Keeler Canyon Formation provides an opportunity to link facies archi tecture to controls on depositional system development. Depositional r elationships indicate that the deposits represent a non-channellized b ase of slope carbonate apron system with inner, outer and basinal faci es associations. These gravity flow deposits are characterized by repe ated stacked, small scale (< 15 m) coarsening and thickening upward cy cles with superimposed medium scale (> 100 m) coarsening and thickenin g upward cycles. Contemporaneous outer shelf and upper slope deposits of the Tippipah Limestone are exposed at Syncline Ridge on the Nevada Test Site. The deposits consist of carbonate buildups directly overlai n by cross bedded, quartz-rich sandstone and conglomerate which filled channels that traversed across the previously existing carbonate shel f. Detritus was transported to the west, down the upper slope by gully systems that fed the temporally persistent base of slope apron of the upper part of the Keeler Canyon Formation. This style of deposition d iffers from point-sourced siliciclastic submarine fan depositional sys tems. However, the Keeler Canyon system has lithofacies similar to som e sandy siliciclastic turbidite systems, such as the delta-fed submari ne ramp facies model, which is a line-sourced, shelf-fed system that i s not supply limited. The mixed clastic apron systems of the Keeler Ca nyon Formation differ from classical carbonate aprons in that the form er is characterized by an abundance of sedimentary cycles. Controls on the development of these cycles and of the facies distribution may ha ve resulted from changes in type and rate of sediment supply, relative sea level changes and/or tectonic events. Interpretation of the data is focused on relative changes in sea level as the most significant co ntrol on development of the depositional system. Relative sea level ch anges serve two important functions: (1) they provide a mechanism for bringing coarse siliciclastic and bioclastic grains together on the ou ter shelf, and (2) shelf margin collapse may be initiated during relat ive lowstands allowing for transport of the sediment to the deep basin and development of deep basinal cycles. Therefore, an abundance of mi xed clastic gravity flow deposits such as these in the rock record may be an indicator of periods of high frequency changes in relative sea level, which is a characteristic of Late Palaeozoic sea level history.