Coeval development of Silurian stromatolite reefs in Alaska and the Ural Mountains: Implications for paleogeography of the Alexander terrane

Soja, Constance M.; Антошкина, А. И.

doi:10.1130/0091-7613(1997)025<0539:cdossr>2.3.co;2

Cited by 47 publications

(19 citation statements)

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“…The perireefal talus slopes accumulated at angles up to 40°. The original vertical dimension of large blocks indicates the minimum amount of primary relief present in these reefs and was locally at least 15 m. Similar displaced blocks do not appear to be known in well-studied Silurian patch reef complexes elsewhere (see Copper & Fay, 1988;Desrochers & Bourque, 1988;Brunton & Copper, 1994;Soja & Antoshkina, 1997;Antoshkina, 1998). The displaced blocks described here show that early Silurian (430 Ma) patch reefs, which were mainly built by stromatoporoid sponges, tabulates and calcareous red algae and cyanobacteria, were capable of developing relief and rigidity comparable with some modern scleractinian coral patch reefs.…”

Section: Introductionmentioning

confidence: 73%

Growth of rigid high‐relief patch reefs, Mid‐Silurian, Gotland, Sweden

Watts

Riding

2000

Sedimentology

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Patch reefs up to 35 m thick and generally 100–150 m wide, separated by bedded inter‐reef sediment, dominate the Högklint Formation (Lower Wenlock) of north‐west Gotland. The spacing between adjacent patch reefs is variable, but is commonly 150–350 m. The Högklint is a shallowing sequence, and the patch reefs exhibit a well‐developed vertical succession: (1) Axelsro‐type patch reefs developed in the underlying Visby Formation; (2) halysitid tabulates capped by laminar stromatoporoids; (3) domical and bulbous stromatoporoids and red algae; (4) cyanobacterial–algal reef crest. The patch reefs expand upwards from an initial bioherm phase with a small base to a laterally extensive biostrome phase. This gives them a thumb‐tack appearance. In stage 2 of the bioherm phase, rigid framework development and high reef relief resulted in breakage of angular blocks up to 15 m long, which were incorporated into the reefs or fell into adjacent sediments. Poorly sorted talus haloes (Millingsklint Member) also developed adjacent to stage 2 of the bioherm phase. These include angular blocks and exhibit depositional slopes up to 40° away from the reefs. Stage 3 biostrome development was mainly non‐rigid cluster reef, which shed skeletal debris (Domkyrka Member) but few lithified blocks. Stage 4 biostrome development was a reef crest with open to closed frame structure. Storm breakage and overturning produced large blocks with complex cavity fill sequences including double geopetals. Relief during the bioherm phase, indicated by fallen blocks and talus slopes, was up to at least 15 m; during the biostrome phase, it was up to 10 m.

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Section: Introductionmentioning

confidence: 73%

Growth of rigid high‐relief patch reefs, Mid‐Silurian, Gotland, Sweden

Watts

Riding

2000

Sedimentology

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“…Only two species have been described fi'om Emsian-Eifelian strata of the Cordilleran Region: Ivdelinia grinnellensis BRICE 1982, and tvdelinia (Ivdelinetla) ellesmerensis BRICE 1982, both of which occur in the Canadian Arctic Islands. The only other part of present-day North Ameriea with similar algal buildups of equivalent age is the Alexander Terrane ofsoutheastern Alaska (SOJA 1994;SOJA & ANTOSHKINA 1997), which also is of accretionary origin. The rhynchonellid brachiopod Sibirirhynchia alata (KHODALEVlCH 1951) occurs in the Shellabarger Pass late Emsian beds; ir has not previously been reported from North America.…”

Section: Biogeographic Significance Of Shellabarger Pass Emsian Brachmentioning

confidence: 99%

Late Early Devonian (Late Emsian) eospiriferinid brachiopods from Shellabarger Pass, south-central Alaska, and their biogeographic importance; further evidence for a Siberian origin of the Farewell and allied Alaskan accreted terranes

Blodgett

Boucot

1999

Senckenbergiana lethaea

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“…Many of the Paleozoic-Mesozoic terranes that make up the northern North American Cordillera have origins in circum-Arctic regions (e.g., Siberia, Bal-tica), intraoceanic settings in the Panthalassic Ocean, or represent displaced peri-Laurentian crustal fragments that developed in proximity to the western margin of ancestral North America (e.g., Nokleberg et al, 2000;Colpron et al, 2007;Colpron and Nelson, 2009;Miller et al, 2011). The Farewell terrane was initially thought to have originated along the western margin of Laurentia (Coney et al, 1980;Box, 1985;Decker et al, 1994;Plafker and Berg, 1994); however, more recent paleontological studies have made the case for an Arctic-margin origin, which could include localities such as Siberia or northern Laurentia (Soja and Antoshkina, 1997;Blodgett et al, 2002;Dumoulin et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Sedimentology, U-Pb detrital geochronology, and Hf isotopic analyses from Mississippian–Permian stratigraphy of the Mystic subterrane, Farewell terrane, Alaska

Malkowski¹,

Hampton²

2014

Lithosphere

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The Farewell terrane of western Alaska is one of the more remote and understudied crustal fragments in the North American Cordillera. Although it is generally accepted that the oldest, Precambrian parts of the Farewell terrane originated along the Arctic margin (i.e., Siberia), the paleogeographic history of the Farewell terrane during much of the middle and late Paleozoic remains unknown. Here, we present new sedimentologic and provenance data from upper Paleozoic clastic strata of the Mystic subterrane, which represents the youngest part of the Farewell terrane. Sedimentary facies consist of high-and low-density sediment-gravity-flow deposits and are interpreted to represent a submarine fan depositional system. Sandstone modal composition trends show a relative abundance of lithic volcanic fragments (~65%) and subordinate occurrences of lithic sedimentary fragments (~15%) and chert (~13%). Laser-ablation-inductively coupled plasma-mass spectrometry analyses of detrital zircons reveal a bulk U-Pb age distribution of Precambrian-Paleozoic grains. U-Pb detrital zircon age spectra from Mississippian strata have a primary peak age between 400 and 325 Ma and secondary peak ages between 480 and 415 Ma and 2000 and 1800 Ma. Devonian-Mississippian zircons exhibit enriched e Hf isotopic values (-3 to-35), whereas Ordovician-Silurian zircons have both enriched (-5 to-25) and depleted (+5 to +14) e Hf values. Age spectra from Permian strata show primary peaks between 320 and 275 Ma and 460 and 415 Ma, with isolated occurrences of Precambrian-age zircons. Pennsylvanian-Permian zircons exhibit depleted e Hf values (+2 to +14). Youngest peak ages support a Mississippian-Early Permian maximum depositional age for this part of the Mystic subterrane. Overall, provenance trends reflect primary detrital contributions from arc and recycled orogen source areas, which included both enriched and primitive magmatic sources. New U-Pb and Hf isotope analyses from the Mystic assemblage match most closely with magmatic source areas of the Alexander and Wrangellia terranes. Findings are consistent with a model where the Farewell terrane was proximal to both the Alexander and Wrangellia terranes by Mississippian-Permian time.

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Coeval development of Silurian stromatolite reefs in Alaska and the Ural Mountains: Implications for paleogeography of the Alexander terrane

Cited by 47 publications

References 0 publications

Growth of rigid high‐relief patch reefs, Mid‐Silurian, Gotland, Sweden

Growth of rigid high‐relief patch reefs, Mid‐Silurian, Gotland, Sweden

Late Early Devonian (Late Emsian) eospiriferinid brachiopods from Shellabarger Pass, south-central Alaska, and their biogeographic importance; further evidence for a Siberian origin of the Farewell and allied Alaskan accreted terranes

Sedimentology, U-Pb detrital geochronology, and Hf isotopic analyses from Mississippian–Permian stratigraphy of the Mystic subterrane, Farewell terrane, Alaska

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