A “FINAL” PULSE OF MAGMATISM IN THE WALLOWA TERRANE, NORTHEASTERN OREGON: LATE TRIASSIC (NORIAN) SLAB DETACHMENT RECORDED IN THE HURWAL FM., SOUTHERN WALLOWA MOUNTAINS

2016 ◽  
Author(s):  
Wesley Gareth Massoll ◽  
◽  
Todd A. LaMaskin
Keyword(s):  
Late Triassic ◽  
Wallowa Terrane

Systematics and Paleoecology of Norian (Late Triassic) Bivalves from a Tropical Island Arc: Wallowa Terrane, Oregon

1987 ◽  
Vol 61 (S22) ◽  
pp. 1-83 ◽  
Author(s):  
Cathryn R. Newton ◽  
Michael T. Whalen ◽  
Joel B. Thompson ◽  
Nienke Prins ◽  
David Delalla
Keyword(s):  
North American ◽  
Island Arc ◽  
Late Triassic ◽  
Small Scale ◽  
Long Distance ◽  
Tropical Island ◽  
North American Cordillera ◽  
The North ◽  
Wallowa Terrane ◽  
Hells Canyon

Early Norian silicified bivalves from Hells Canyon in the Wallowa terrane of northeastern Oregon are part of a rich molluscan biota associated with a tropical island arc. The Hells Canyon locality preserves lenses of silicified shells formed as tempestites in a shallow subtidal carbonate environment. These shell assemblages are parautochthonous and reflect local, rather than long-distance, transport. Silicification at this locality involved small-scale replacement of original calcareous microstructures, or small-scale replacement of neomorphosed shells, without an intervening phase of moldic porosity. This incremental replacement of carbonate by silica contrasts markedly with void-filling silicification textures reported previously from silicified Permian bivalve assemblages.The bivalve paleoecology of this site indicates a suspension feeding biota existing on and within the interstices of coral-spongiomorph thickets, and inhabiting laterally adjacent substrates of peloidal carbonate sand. The bivalve fauna is ecologically congruent with the reef-dwelling molluscs associated with Middle Triassic sponge-coral buildups in the Cassian Formation of the Dolomites (Fuersich and Wendt, 1977). Hells Canyon is a particularly important early Norian locality because of the diversity of substrate types and because the site includes many first occurrences of bivalves in the North American Cordillera. These first occurrences include the first documentation of the important epifaunal families Pectinidae and Terquemiidae in Triassic rocks of the North American Cordillera.The large number of biogeographic and geochronologic range extensions discovered in this single tropical Norian biota indicates that use of literature-based range data for Late Triassic bivalves may be very hazardous. Many bivalve taxa formerly thought to have gone extinct in Karnian time have now been documented from Norian strata in this arc terrane. These range extensions, coupled with the high bivalve species richness of the Hells Canyon site, suggest that the Karnian mass extinction in several literature-based compilations may be an artifact of incomplete sampling. Even for the Norian, present compilations of molluscan extinction may have an unacceptably large artifactual component.Thirty-five bivalve taxa from the Hells Canyon locality are discussed. Of these, seven are new: the mytilid Mysidiella cordillerana n. sp., the limacean Antiquilima vallieri n. sp., the true oyster Liostrea newelli n. sp., the pectinacean Crenamussium concentricum n. gen. and sp., the unioid Cardinioides josephus n. sp., the trigoniacean Erugonia canyonensis n. gen. and sp., and the carditacean Palaeocardita silberlingi n. sp.

Giant Upper Triassic bivalves of Wrangellia, Vancouver Island, Canada

2013 ◽  
Vol 50 (2) ◽  
pp. 142-147
Author(s):  
George D. Stanley ◽  
Thomas E. Yancey ◽  
Hannah M.E. Shepherd
Keyword(s):  
North America ◽  
Vancouver Island ◽  
Upper Triassic ◽  
Warm Water ◽  
Late Triassic ◽  
Fine Grained ◽  
Large Size ◽  
Wallowa Terrane ◽  
Volcanic Islands ◽  
First Time

One of the most distinctive components of the Late Triassic warm-water biota are alatoform, reclining bivalves of the genus Wallowaconcha. Wallowaconcha raylenea was first described from shallow-water, fine-grained Upper Triassic carbonate rocks of the Wallowa terrane, northeastern Oregon, and later found in coeval limestone in the Yukon. Fossils of the family Wallowaconchidae are easily recognized and readily distinguished from other fossil groups by their large size (over a metre in length), alatoform morphology, and especially the chambered wing-like extensions likely associated with photosymbiosis. Several different taxa of Norian age inhabited lagoon and reef-related settings on four separate terranes of western North America (Antimonio terrane, Sonora, Mexico; Wallowa terrane, northeastern Oregon; Stikine terrane in the Yukon; Chulitna terrane of Alaska), which during Triassic time existed as volcanic islands in the eastern Panthalassa Ocean. Outside eastern Panthalassa in the eastern Tethys, two other species of Wallowaconcha come from distant localities in Asia and Arabia. We here report for the first time, in presumed Rhaetian limestone of the upper part of the Parson Bay Formation, Vancouver Island, newly discovered examples of Wallowaconcha. They are from Wrangellia and, based on size and shape of the chambers, are assignable to W. raylenea but unlike other examples they appear to be Rhaetian in age. This species of giant bivalve inhabited warm-water locales outboard of North America during the Late Triassic, and its presence provides possible paleobiogeographic links of Wrangellia with both Stikinia and the Wallowa terrane.

Late Triassic dasycladacean alga from northeastern Oregon: significance of first reported occurrence in western North America

1989 ◽  
Vol 63 (3) ◽  
pp. 374-381 ◽  
Author(s):  
Erik Flügel ◽  
Baba Senowbari-Daryan ◽  
George D. Stanley
Keyword(s):  
United States ◽  
North America ◽  
Western Europe ◽  
The United States ◽  
Upper Triassic ◽  
Late Triassic ◽  
Western North America ◽  
Dispersal Abilities ◽  
Wallowa Terrane ◽  
Fossil Alga

An Upper Triassic metaspondyle dasycladacean alga,Diplopora oregonensisn. sp., is described from the Hurwal Formation, southern Wallowa Mountains, northeastern Oregon. It occurs in the accreted Wallowa terrane, which is interpreted as far-travelled relative to the craton of North America. The fossil alga is found in limestone clasts within a limestone–chert–volcanic clast conglomerate of the Hurwal Formation. The new species is related toDiploplora borzaiBystricky, known from the Upper Triassic of the Carpathian Mountains and Sicily, but is distinguished by very small branches and a distinct segmentation of the thalli.Diplopora oregonensisis the first Triassic dasycladacean alga known from the United States, and perhaps from all of North America. The absence of calcareous green algae from rocks of cratonal North America, as well as from most Triassic displaced terranes of the eastern and western Pacific, is in stark contrast to counterparts in the former Tethys region of central Europe, where dasycladacean algae were abundant and contributed significantly to the sediment. This paucity of algae may be related to differences in environment, but more likely is linked to the paleogeographic situation and dispersal abilities of the algae. The similarity of the Oregon dasyclads to species in western Europe, coupled with the lack of dasyclad algae in any other part of North America, is evidence in support of a far-travelled nature for the Wallowa terrane.

New Late Triassic gastropods from the wallowa Terrane (Idaho) and their biogeographic significance

Facies ◽  
2001 ◽  
Vol 45 (1) ◽  
pp. 87-92 ◽  
Author(s):  
Alexander Nützel ◽  
Douglas H. Erwin
Keyword(s):  
Late Triassic ◽  
Wallowa Terrane

Late Triassic (Late Norian) gastropods from the Wallowa Terrane (Idaho, USA)

PalZ ◽  
2004 ◽  
Vol 78 (2) ◽  
pp. 361-416 ◽  
Author(s):  
Alexander Nützel ◽  
Douglas H. Erwin
Keyword(s):  
Late Triassic ◽  
Wallowa Terrane

Triassic sponges (Sphinctozoa) from Hells Canyon, Oregon

1988 ◽  
Vol 62 (03) ◽  
pp. 419-423 ◽  
Author(s):  
Baba Senowbari-Daryan ◽  
George D. Stanley
Keyword(s):  
Endemic Species ◽  
Upper Triassic ◽  
Island Arc ◽  
Tropical Island ◽  
The Family ◽  
Wallowa Terrane ◽  
Unique Condition ◽  
Hells Canyon

Two Upper Triassic sphinctozoan sponges of the family Sebargasiidae were recovered from silicified residues collected in Hells Canyon, Oregon. These sponges areAmblysiphonellacf.A. steinmanni(Haas), known from the Tethys region, andColospongia whalenin. sp., an endemic species. The latter sponge was placed in the superfamily Porata by Seilacher (1962). The presence of well-preserved cribrate plates in this sponge, in addition to pores of the chamber walls, is a unique condition never before reported in any porate sphinctozoans. Aporate counterparts known primarily from the Triassic Alps have similar cribrate plates but lack the pores in the chamber walls. The sponges from Hells Canyon are associated with abundant bivalves and corals of marked Tethyan affinities and come from a displaced terrane known as the Wallowa Terrane. It was a tropical island arc, suspected to have paleogeographic relationships with Wrangellia; however, these sponges have not yet been found in any other Cordilleran terrane.

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