Permian of the Western United States

Wardlaw, Bruce R.; Snyder, W.S.; Spinosa, Claude; Gallegos, Dora M.

doi:10.1007/978-3-642-78590-0_2

Cited by 8 publications

(3 citation statements)

References 20 publications

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“…The same applies for western Canada where the upper part of the Fantasque chert could range into the Lopingian (Table 1, Henderson and Mei, 2000) and may be overlain conformably by Early Triassic mudrocks of the Spray River Group (Wang et al, 1994). Lopingian strata are missing beneath the Early Triassic Dinwoody Formation in the Phosphoria Basin of the western USA (Wardlaw et al, 1995), but Lopingian cherts most occur widely in the upper part of the various allochtonous and exotic units from Alaska to California (Cordey, 1998;Cordey et al, 1999).…”

Section: Zenith Of Pce: Lopingianmentioning

confidence: 97%

“…1), which also locally contain some dropstones (Beauchamp, 1994). The impoverished biotic composition of the Degerbo « ls carbonates, the lack of marine cement, and the presence of dropstones (£oating ice) and of glauconite (slow sedimentation rate) indicate that the Sverdrup Basin area was bathed by Wardlaw, 1980;Mytton et al, 1983;Wardlaw and Collinson, 1986;Breuninger et al, 1989;Wardlaw et al, 1995 3. SW Alberta …”

Section: Expansion Of Pce: Guadalupianmentioning

confidence: 99%

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Growth and demise of Permian biogenic chert along northwest Pangea: evidence for end-Permian collapse of thermohaline circulation

Beauchamp

Baud

2002

Palaeogeography, Palaeoclimatology, Palaeoecology

267

132

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The Permian Chert Event (PCE) was a 30 Ma long episode of unusual chert accumulation along the northwest margin of Pangea, and possibly worldwide. The onset of the PCE occurred at about the Sakmarian^Artinskian boundary in the Sverdrup Basin, Canadian Arctic, where it coincides with a maximum flooding event, the ending of high-frequency/high-amplitude shelf cyclicity, the onset of massive biogenic chert deposition in deep-water distal areas, and a long-term shift from warm-to cool-water carbonate sedimentation in shallow-water proximal areas. A similar and coeval shift is observed from the Barents Sea to the northwestern USA. A landward and southward expansion of silica factories occurred during the Middle and Late Permian at which time warm-water carbonate producers disappeared completely from the northwest margin of Pangea. Biotically impoverished and increasingly narrow cold-water carbonate factories (characterised by non-cemented bioclasts of sponges, bryozoans, echinoderms and brachiopods) were then progressively replaced by silica factories. By Late Permian time, little carbonate sediments accumulated in the Barents Sea and in the Sverdrup Basin, where the deep-to shallow-water sedimentary spectrum was occupied by siliceous sponge spicules. By that time, biogenic silica sedimentation was common throughout the world. Silica factories collapsed in the Late Permian, abruptly bringing the PCE to an end. In northwest Pangea, the end-Permian collapse of the PCE was associated with a major transgression and with a return to much warmer oceanic and continental climatic conditions. Chert deposition resumed in the distal oceanic areas during the early Middle Triassic (Anisian) after a 8^10 Ma interruption (Early Triassic Chert Gap). The conditions necessary for the onset, expansion and zenith of the PCE were provided by the thermohaline circulation of nutrient-rich cold waters along the northwestern and western margin of Pangea, and possibly throughout the world oceans. These conditions provided an efficient transportation mechanism that constantly replenished the supply of silica in the area, created a nutrient-and oxygen-rich environment favouring siliceous biogenic productivity, established cold sea-floor conditions, hindering silica dissolution, while increasing calcium carbonate solubility, and provided conditions adverse to organic and inorganic carbonate production. The northwest margin of Pangea was, for nearly 30 Ma, bathed by cold waters presumably derived from the seasonal melting of northern sea ice, the assumed engine for thermohaline circulation.This process started near the Sakmarian^Artinskian boundary, intensified throughout Middle and Late Permian time and ceased suddenly in latest Permian time. It led to oceanic conditions much colder than normally expected from the palaeolatitudes, and the influence of cold northerly-derived water was felt as far south southern Nevada. The demise of silica factories was caused by the rapid breakdown of these conditions and the establishment of a much warm...

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Section: Zenith Of Pce: Lopingianmentioning

confidence: 97%

Section: Expansion Of Pce: Guadalupianmentioning

confidence: 99%

Growth and demise of Permian biogenic chert along northwest Pangea: evidence for end-Permian collapse of thermohaline circulation

Beauchamp

Baud

2002

Palaeogeography, Palaeoclimatology, Palaeoecology

267

132

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“…Rather, it may simply reflect the lack of preservation of any coeval cratonal rock units outside the Phosphoria basin. Wardlaw et al (1994) documented a major unconformity that removed most of the Guadalupian through Lower Triassic strata in the western United States. Within the study area, the only preserved Guadalupian rocks are those of the Phosphoria Formation and time-equivalent strata deposited on anomalously low areas on the Wyoming shelf (Fig.…”

Section: Source Of Meade Peak Siltstonementioning

confidence: 99%

Eolian-derived siltstone in the Upper Permian Phosphoria Formation: Implications for marine upwelling

Carroll

Stephens

Hendrix

et al. 1998

Geol

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Previously described organic-rich shale facies of the Meade Peak Member of the Phosphoria Formation at Soda Springs, Idaho, consist of well-sorted, laminated siltstone containing little or no clay. The planar-parallel fabric preserved in many of the siltstone beds suggests suspension settling onto the outer shelf or upper slope, most likely under low oxygen conditions. Evidence for transport of silt to the depositional site by sediment gravity flows is absent, as are sandstone beds. We propose that Meade Peak siltstone facies record subaqueous deposition of windborne silt that was transported southward from central Montana. As such, they provide the first direct geologic evidence of a wind regime favorable for marine upwelling, the process commonly postulated to have localized the deposition of Permian phosphatic sediments. They may also provide indirect evidence of upwind eolian sand transport at that time. Figure 1. Paleogeography of Phosphoria Formation (modified from Maughan, 1984), and surface wind directions derived from GENESIS v. 2.0 global climate model (J. E. Kutzbach and M. Gibbs, 1998, personal commun.). "Winter" wind direction is averaged over December-January-February; "summer" is over June-July-August.

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High‐resolution Lopingian (Late Permian) timescale of South China

et al. 2010

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The Lopingian represents the last epoch of the Palaeozoic Era and is bracketed by two severe biotic mass extinctions associated with dramatic environmental changes. The Lopingian Epoch lasted about 7 millions years and was also bracketed by large volcanic eruptions with the Emeishan volcanics at the base and the Siberian traps at the top. Considerable data have accumulated recently and in this paper we attempt to summarize these findings in a high-resolution Lopingian (Late Permian) timescale that integrates currently available multiple biostratigraphic, isotope chemostratigraphic, geochronologic and magnetostratigraphic data. In South China at least 13 conodont zones, multiple polarity zones and large carbon isotope fluctuations in the Lopingian are recognized and provide the high-resolution calibration that is essential to study this Late Permian interval characterized by Earth's largest biotic extinction. We also present a global correlation chart for the marine Lopingian Series.

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Permian of the Western United States

Cited by 8 publications

References 20 publications

Growth and demise of Permian biogenic chert along northwest Pangea: evidence for end-Permian collapse of thermohaline circulation

Growth and demise of Permian biogenic chert along northwest Pangea: evidence for end-Permian collapse of thermohaline circulation

Eolian-derived siltstone in the Upper Permian Phosphoria Formation: Implications for marine upwelling

High‐resolution Lopingian (Late Permian) timescale of South China

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