About This Item
- Full TextFull Text(subscription required)
- Pay-Per-View PurchasePay-Per-View
Purchase Options Explain
Share This Item
Sussex sandstone produces oil in a stratigraphic trap at House Creek field in the south-central Powder River basin. The total thickness of the Sussex is 40 ft (12 m) and reservoir sandstone is as much as 30 ft (9 m) thick, about 1 mi (1.6 km) wide, and 25 mi (40 km) long. The sandstone is probably of marine origin but has an unexpected bedding sequence: (1) an upper bioturbated mudstone that contains scattered granules of chert; (2) thin, coarse-grained, pebbly sandstone; (3) thin-bedded, cross-laminated sandstone with deformed shale clasts; (4) ripple-bedded sandstone with shale laminae; and (5) a basal shale that contains ripple lenses of sandstone and rare bioturbation. Mean size of quartz is 0.22 mm (fine grained), and grain size increases upward from 0.13 mm at the b se to 0.28 mm in the pebbly sandstone. The sandstone contains monocrystalline quartz, 48 percent; feldspar, 11; polycrystalline quartz, 10; chert, 13; and clay matrix, glauconite, and chlorite, 15 percent. The Sussex represents a prograding sequence of sand that was transported southeastward by low-flow-regime currents along a relatively shallow, marine shelf. Bioturbation, stratigraphic position, and similarity to other sandstones in the same sequence suggest a neritic environment of water depths in the range of 100 to 200 ft (31 to 62 m). The thin, pebbly sandstone is not fully explained because its coarse texture suggests stronger, perhaps channelized, currents. Nevertheless, the narrow, prograding sequence probably represents a major transport route for sand across the shelf toward a deeper basin beyond.
Pay-Per-View Purchase Options
The article is available through a document delivery service. Explain these Purchase Options.
|Protected Document: $10|
|Internal PDF Document: $14|
|Open PDF Document: $24|
Members of AAPG receive access to the full AAPG Bulletin Archives as part of their membership. For more information, contact the AAPG Membership Department at [email protected].