Cycle stratigraphy as a paleogeographic tool: Point Lookout Sandstone, southeastern San Juan basin, New Mexico

Wright, Robyn

doi:10.1130/0016-7606(1986)97<661:csaapt>2.0.co;2

Cited by 15 publications

(16 citation statements)

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“…23), dense Thalassinoides bioturbation (Fig. 20) is interpreted to have formed in a brackish lagoon perhaps 20-30km landward of the shoreline; Teredolites in the same unit provide additional evidence for saline conditions (Wright 1986). Similarly, the incursion of salt water onto the coastal plain in sequence G (Fig.…”

Section: Transgressive Systems Tractmentioning

confidence: 95%

Marine and nonmarine systems tracts in fourth-order sequences in the Early-Middle Cenomanian, Dunvegan Alloformation, northeastern British Columbia, Canada

Plint

1996

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The Early to Middle Cenomanian Dunvegan Alloformation is a 3rd-order clastic sequence that was deposited on the western margin of the Alberta foreland basin. The alloformation, comprising ten allomembers (A-J) has been mapped over 33 000 km 2 using 1500 well logs and 40 outcrops. Regional flooding surfaces are used to define allomembers because they are more reliably identified in well logs than are Exxon-type unconformities (although in many instances unconformities and flooding surfaces are coplanar). The Dunvegan records episodic deltaic progradation from NW to SE along the axis of the foreland basin. This paper focuses on an 800 km 2 study area in NE British Columbia where both shallow marine and coastal plain strata are exposed in the valleys of the Peace and Beatton rivers. Marine strata comprise sandier-upward successions that grade from platy mudstone through era-scale interbeds of wave rippled fine sandstone to dm-scale beds of HCS, commonly including large gutter casts. Successions may be capped by SCS and crossbedded, fine-grained sandstone, sometimes with a rooted top. The succession of facies suggests a strongly wave-influenced deltaic shoreline. Gutter casts are consistently orientated shore-normal and appear to have been formed by oscillatory wave scour during storms. Sandstone distribution varies between successive progradational packages ('shingles') in allomember J, suggesting that delta switching was an important control on depositional cyclicity. Coastal plain deposits include small-scale (few metres) coarseningupward successions of carbonaceous mudstone, siltstone and fine sandstone interpreted as lake and bay-fill deposits. Decimetre scale sharp-based sandstones may represent crevasse splays whereas lenticular, rippled and crossbedded sandstones were probably deposited in distributary channels. Rooted palaeosols are abundant. Both coastal plain and marine strata are locally replaced by erosive-based bodies of cross-bedded sandstone up to 25 m thick and 0.5-3 km wide, interpreted as incised valley falls underlain by type 1 sequence boundaries. Additional evidence of relative sea-level fall is provided by regressive surfaces of marine erosion beneath sharp-based shoreface sandstones. If attached to highstand deposits, these sandstones are assigned to the falling stage systems tract, whereas detached sandstones are assigned to the lowstand systems tract. During the early part of the transgressive systems tract, sedimentation was confined to incised valleys but later, interfluves were buried by sediments that locally contain dense Thalassinoides burrow systems, Teredolites and welldeveloped mud drapes, suggestive of brackish, tidally-influenced conditions. Overlying coastal plain strata lack evidence of marine influence and are attributed to the highstand systems tract.

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Section: Transgressive Systems Tractmentioning

confidence: 95%

Marine and nonmarine systems tracts in fourth-order sequences in the Early-Middle Cenomanian, Dunvegan Alloformation, northeastern British Columbia, Canada

Plint

1996

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“…6; sections 1 and 2). In the Campanian of the San Juan Basin, similar features are thought to be typical of delta front settings (Wright, 1986). Overlying the amalgamated hummocky cross-stratified facies are massive, slightly finer grained and better sorted sandstones that are inferred to represent the middle shoreface environment ( Fig.…”

Section: Lithofacies Environments and Processesmentioning

confidence: 90%

Cyclic facies architecture as a key to depositional controls in a distal foredeep: Campanian Mesaverde Group, Wyoming, USA

Klug¹

1993

Geol Rundsch

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The Mesaverde Group consists of a thick wedge of fluvial, littoral-deltaic and shallow marine clastics shed into the Cretaceous Western Interior Seaway of North America. The western parts of the seaway lay within the strongly subsiding foredeep of the active Sevier fold and thrust belt further to the west. The study area is located east of the axis of maximum subsidence and is thus in a favourable position to record competing effects of eustasy, sediment supply and thrust-load induced subsidence. Facies and sequence analysis carried out on high quality outcrop and well log data led to the recognition of a complex depositional cycle hierarchy within the typical storm-and wavedominated inner shelf/shoreface/strand plain and delta systems of the Mesaverde.Fourth-order parasequences and parasequence bundles of estimated 1 0 0 -4 0 0 k a duration are the best recognizable, ubiquitous and most useful stratigraphic units. Their arrangement with respect to sequence boundaries, however, varies with their overall stratigraphic position and also differs from the Exxon models. Mesaverde progradation was interrupted by a major transgression that occurred out of phase with the aggradational to progradational stacking trend of third-order sequences. A proposed genetic model relates large-scale (secondorder) sequence architecture to tectonics: a Sevier thrust event as well as Laramide uplift within the foredeep controlled non-linear changes in the accommodation/supply ratio. Parasequence stacking patterns and sequence boundary formation, in contrast, were the product of (global?) eustasy enhanced by short-term, perhaps local, changes in the rates of subsidence and detrital influx.

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“…5) suggests that these horizons represent periods of reduced clastic input associated with transgression and deepening. Similar transgression planes overlain by thin mudstone units are reported from stacked regressive shoreline sediments of the Cretaceous Point Lookout Sandstone of New Mexico (Wright 1986). Stacked regressive shoreline sandstones are recorded from elsewhere in the Cretaceous western interior seaway of North America, where up to six coarseningupwards, marine sheet sands may occur separated by thin transgressive marine mudstones (Balsley 1980;Levey 1985).…”

Section: Depositional Environmentsmentioning

confidence: 92%

A composite tectonic–eustatic origin for shelf sandstones at the Cambrian–Ordovician boundary in North Greenland

Bryant

Smith

1990

JGS

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Shelf sandstones deposited at the Cambrian-Ordovician boundary in central and western North Greenland have a sheet-like large-scale geometry, and extend for over 300 km along strike within a shallow marine, carbonate-dominated, platform sequence. Conodont faunas from units above and below the most extensive sand sheet, the Kap Coppinger Member of the Cass Fjord Formation and the Permin Land Formation, indicate that deposition of the sands spanned the proauus, intermedius and lindstromi conodont biozones. Sand was derived by reworking of older, quartzitedominated formations following the uplift and unroofing of a platform bulge to the east. During the Cambrian, this sediment was transported northwards from the uplifted area across an unstable platform into a deep-water trough. However, during sea-level lowstands within the CambrianOrdovician boundary interval this clastic material was deflected westwards and transported across the stable platform by progradation of tide-and storm-dominated shorelines. Facies sequences in the thickest part of the Permin Land Formation suggest at least three such regressive cycles combined to form a composite sand body. Each regressive cycle comprises a shallowing upward transition from tide-and storm-deposited marine sediments to clean sandstones of marine or terrestrial origin. The cycles are separated by thin but laterally extensive dolomites interpreted to represent drowning events. Thinner sequences further to the east are attributed to reduced accommodation space as a consequence of lower subsidence rates close to the uplifted source area, whilst thin sequences in the west are ascribed to the effect of increasing distance from the sediment source so that only the youngest of the three regressive cycles is present.

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Cycle stratigraphy as a paleogeographic tool: Point Lookout Sandstone, southeastern San Juan basin, New Mexico

Cited by 15 publications

References 0 publications

Marine and nonmarine systems tracts in fourth-order sequences in the Early-Middle Cenomanian, Dunvegan Alloformation, northeastern British Columbia, Canada

Marine and nonmarine systems tracts in fourth-order sequences in the Early-Middle Cenomanian, Dunvegan Alloformation, northeastern British Columbia, Canada

Cyclic facies architecture as a key to depositional controls in a distal foredeep: Campanian Mesaverde Group, Wyoming, USA

A composite tectonic–eustatic origin for shelf sandstones at the Cambrian–Ordovician boundary in North Greenland

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