Depositional environment and diagenesis of Teapot Sandstone (Upper Cretaceous), Converse and Natrona counties, Wyoming
The Teapot Sandstone forms the upper member of the Upper Cretaceous Mesa Verde Formation in the Powder River basin. Previous interpretations of the Teapot based on outcrop or subsurface data range from nearshore marine to fluvial. Marine lithofacies coarsen upward from bioturbated offshore siltstone to nearshore sandstone with large, pellet-lined ophiomorpha and overlying well-sorted, horizontally laminated foreshore sandstone exhibiting ridge and runnel topography. Marine foreshore sandstone is overlain by complexly interbedded sandstone and carbonaceous shale in stacked fining-upward sequences of the delta plain. Fining-upward units are interpreted as abandoned channels, whereas coarsening-upward sequences are interpreted as interdistributary bay or lagoonal deposits. Capping the sequence is a thick, cross-bedded fluvial section consisting of levee, point bar, and channel sand deposits. The Teapot Sandstone has a complex diagenetic history. Siderite and framboidal pyrite formed early in the diagenetic sequence at shallow depths of burial under anaerobic conditions. Pore-filling kaolinite, chlorite, and quartz overgrowths formed coevally following dissolution of relatively unstable framework grains. Poikilotopic calcite cement is locally abundant and extensively replaces framework grains. Nearshore marine and fluvial sandstone are potentially hydrocarbon reservoirs, although authigenic clays have significantly reduced permeability. Reservoir potential of well-sorted foreshore marine sandstone was destroyed by pore-filling calcite cement. However, tightly cemented sandstone forms a potential diagenetic trapping mechanism.
- Research Organization:
- AGAT Consultants, Inc., Denver, CO
- OSTI ID:
- 6386250
- Report Number(s):
- CONF-8309274-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 67:8; Conference: AAPG Rocky Mountain Section meeting, Billings, MT, USA, 18 Sep 1983
- Country of Publication:
- United States
- Language:
- English
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