Upper Triassic Invertebrates from the Antimonio Formation, Sonora, Mexico

1994 ◽  
Vol 68 (S36) ◽  
pp. 1-33 ◽  
Author(s):  
George D. Stanley ◽  
Carlos González-León ◽  
Michael R. Sandy ◽  
Baba Senowbari-Daryan ◽  
Peter Doyle ◽  
...  
Keyword(s):  
North America ◽  
North American ◽  
Weak Link ◽  
Upper Triassic ◽  
Marine Fauna ◽  
Western Tethys ◽  
The North ◽  
Tethys Realm ◽  
First Occurrence ◽  
North American Craton

A diverse Upper Triassic tropical marine fauna from northwestern Sonora, Mexico, includes 31 taxa of tropical invertebrates including scleractinian corals, spongiomorphs, disjectoporoids, “hydrozoans,” thalamid and nonthalamid sponges, spiriferid and terebratulid brachiopods, gastropods, bivalves, coleoids, and anomuran microcoprolites. They occur within the late Karnian to Norian part of the Antimonio Formation (Antimonio terrane), which is juxtaposed against a fragmented portion of the North American craton. Most of the fauna is also known from the Tethys region. Sixteen Sonoran taxa co-occur in the western Tethys and five have never been known outside this region. Four additional taxa (one identified only at genus level) are geographically widespread. Some taxa occur in displaced terranes of North America, especially in west-central Nevada (Luning Formation). A weak link exists with the California Eastern Klamath terrane but stronger ties exist with Peru. Among Sonoran sponges,Nevadathalamia polystomawas previously recognized only from the Luning Formation, western Nevada. SpongesCinnabaria expansa, Nevadathalamia cylindrica, and a coral,Astraeomorpha sonorensisn. sp., are also known from Nevada. The coralsDistichomeandra austriaca, Chondrocoenia waltheri, Pamiroseris rectilamellosa, andAlpinophyllia flexuosaco-occur in central Europe. Two new taxa, a spongiomorph hydrozoan,Stromatoporidium lamellatumn. sp., and a disjectoporoid,Pamiropora sonorensisn. sp., have distinct affinities with the Tethys. The geographically widespread North American brachiopod,Spondylospira lewesensis, andPseudorhaetina antimoniensisn. gen. and sp. are among the Sonoran fauna. The Sonoran coleoid (aulacocerid)Dictyoconites(Dictyoconites) cf.D. reticulatumoccurs in the Tethys realm andCalliconitescf.C. drakeiis comparable with a species from the Eastern Klamath terrane.Calliconites millerin. sp. is the first occurrence of the genus outside Sicily. The bivalvesMyophorigonia jaworskii, M. salasi, andPalaeocardita peruvianaare known from Sonora and Peru. Eight gastropod taxa includeGuidoniacf.G. intermediaandG.cf.G. parvula, both previously known from Peru, andEucycloscala subbisertusfrom the western Tethys. The gastropods are unlike those already known from other North American terranes.

The occurrence of the hydrozoan genus Cassianastraea from Upper Triassic (Carnian) rocks of Williston Lake, British Columbia, Canada

2011 ◽  
Vol 85 (1) ◽  
pp. 29-31
Author(s):  
George D. Stanley ◽  
John-Paul Zonneveld
Keyword(s):  
British Columbia ◽  
North America ◽  
Coral Reefs ◽  
North American ◽  
Upper Triassic ◽  
Geological Survey ◽  
The North ◽  
Lake Region ◽  
First Occurrence ◽  
North American Craton

Cassianastraea is an enigmatic colonial Triassic cnidarian first described as a coral but subsequently referred to the Hydrozoa. We report here the first occurrence in Canada of fossils we designate as Cassianastraea sp. from the Williston Lake region of British Columbia. The specimens come from older collections of the Geological Survey of Canada, collected in Upper Triassic (Carnian) strata assigned to either the Ludington or Baldonnel Formations. While well known in reef associations of the former Tethys region, Cassianiastraea is relatively rare in North America. The Carnian Baldonnel Formation contains the earliest coral reefs from the North American craton and we suspect that Cassianastraea sp. also came from this reef association.

Upper Triassic sponges (Sphinctozoa) from southern Yukon, Stikinia terrane

1987 ◽  
Vol 24 (5) ◽  
pp. 882-902 ◽  
Author(s):  
Baba Senowbari-Daryan ◽  
R. Pamela Reid
Keyword(s):  
Pacific Ocean ◽  
North America ◽  
North American ◽  
Upper Triassic ◽  
The North ◽  
North American Craton ◽  
First Time ◽  
Sponge Reefs

The first Tethyan-type Upper Triassic sponge reefs in North America have recently been discovered in the southern Yukon, in Stikinia terrane. Sphinctozoa from these reefs and inter-reef limestones are represented by 18 species and 12 genera belonging to six families. The genus Yukonella with one species, Y. rigbyi, and the species Polytholosia ramosa and Polycystocoelia norica are described for the first time. Some of the Yukon sponges were previously known only from the Tethyan realm (Colospongia, Dictyocoelia, Polycystocoelia, and Uvanella?); others, from Tethyan and North American localities (Ascosymplegma, Follicatena, Paradenigeria, and Salzburgia?). One (Polytholosia cylindrica) is probably endemic to North America. The mixed affinities of the Yukon sponges may reflect the paleogeographic origin of Stikinia as an island in the ancestral Pacific Ocean, between Tethys and the North American craton.

Kilometre-scale folding in the Teslin zone, northern Canadian Cordillera, and its tectonic implications for the accretion of the Yukon-Tanana terrane to North America

1999 ◽  
Vol 36 (3) ◽  
pp. 479-494 ◽  
Author(s):  
Martin de Keijzer ◽  
Paul F Williams ◽  
Richard L Brown
Keyword(s):  
North America ◽  
Shear Zone ◽  
North American ◽  
Root Zone ◽  
Fault System ◽  
Canadian Cordillera ◽  
The West ◽  
The North ◽  
South Central ◽  
North American Craton

The Teslin zone in south-central Yukon has previously been described as a discrete zone with a steep foliation unique to the zone. It includes the Anvil assemblage and the narrowest portion of the Yukon-Tanana terrane (the Nisutlin assemblage), and is defined by post-accretionary faults: the Big Salmon fault to the west and the d'Abbadie fault system to the east. The zone was interpreted as a lithospheric suture or a crustal-scale transpression zone, and as the root zone of klippen lying on the North American craton to the east. We demonstrate that deformation and metamorphism are the same inside and outside the zone. The steep transposition foliation in the zone, in contrast to adjacent rocks to the east, coincides with the steep limb of a regional F3 structure. This fold has a shallow limb in the easternmost part of the zone and immediately east of the zone. Thus we reject earlier interpretations. If a suture exists between the obducted Anvil and Yukon-Tanana Nisutlin assemblages and North America, it is a shear zone that occurs at the base of the obducted rocks, which has been folded by the F3 fold. However, evidence that this thrust boundary is a lithospheric suture is lacking. A consequence of our interpretation is that North American rocks pass under the eastern Teslin zone and outcrop to the west of the Nisutlin and Anvil assemblages. This geometry precludes the possibility of the Teslin zone being the root zone of the klippen.

scholarly journals Graptolite and conodont faunas in Ordovician Vinini Formation, Roberts Mountains, central Nevada, demonstrate that the Roberts Mountains allochthon is not an exotic terrane

1992 ◽  
Vol 6 ◽  
pp. 97-97
Author(s):  
Stanley C. Finney ◽  
Raymond L. Ethington
Keyword(s):  
North America ◽  
Shallow Water ◽  
North American ◽  
Cold Water ◽  
Turbidity Currents ◽  
Plate Tectonic ◽  
Continental Rise ◽  
The North ◽  
North American Craton ◽  
Back Arc

Two very different plate-tectonic models have been proposed to explain the development and emplacement of the Robert Mountains allochthon (RMA) onto the North America craton during the Late Devonian-Early Mississippian Antler Orogeny. In one model, the RMA represents a far-traveled accretionary prism that migrated eastwards over a west-dipping subduction zone. In the other, the eugeoclinal strata of the RMA were deposited on the continental rise of western North America within a closed back-arc basin. Siliciclastic sediments, especially quartz sandstones, compose much of the RMA, yet knowledge of their provenance is poor even though such knowledge is essential for evaluating the two plate-tectonic models.We have recently obtained large collections of graptolites and conodonts from turbiditic quartz sandstones in the Lower Member of the Vinini Formation in the Roberts Mountains. These sandstones of lower Whiterockian age are correlative with the lower Antelope Valley Limestone that deposited on the western shelf of North America. The diverse graptolite fauna represents the oceanic isograptid fauna. However, it also includes pendent didymograptids and rooted dendroids that were restricted to shallow shelf seas. The dendroids (Cactograptus, Dendrograptus, Desmograptus, and Dictyonema) were benthic organisms, could not have lived in a deep marine setting, and are also common in shallow-water carbonate strata of western Utah. All specimens within the turbiditic quartz sandstones of the Vinini were broken before final deposition and burial, but specimens from Utah are generally complete. The diverse conodont fauna is virtually identical to that found in the lower Antelope Valley Limestone, as well as in coeval strata in western Utah. Although it includes a few deep (cold) water, cosmopolitan species, it is dominated by species that are otherwise known only from shallow water strata deposited on the North American craton.We conclude that turbidity currents transported these exotic graptolites and conodonts down from the shelf and onto the rise along with the quartz sands in which they occur. Thus, the Whiterockian quartz sandstones in the Vinini Formation must have a North American provenance just as the fossils do. This is strong evidence that 1) the RMA is not exotic to North America, 2) the eugeoclinal strata of the RMA were deposited on the western continental rise of North America and on the eastern side of a back-arc basin, and 3) the RMA was thrust onto the western shelf of North America by closure of this back-arc basin.

Oldest scleractinian coral reefs on the North American craton: Upper Triassic (Carnian), northeastern British Columbia, Canada

2007 ◽  
Vol 243 (3-4) ◽  
pp. 421-450 ◽  
Author(s):  
John-Paul Zonneveld ◽  
Charles M. Henderson ◽  
George D. Stanley ◽  
Michael J. Orchard ◽  
Murray K. Gingras
Keyword(s):  
British Columbia ◽  
Coral Reefs ◽  
North American ◽  
Scleractinian Coral ◽  
Upper Triassic ◽  
The North ◽  
North American Craton

Lithospheric processes and products in the southern Canadian Cordillera: a Lithoprobe perspective

1995 ◽  
Vol 32 (10) ◽  
pp. 1803-1824 ◽  
Author(s):  
Frederick A. Cook
Keyword(s):  
North America ◽  
North American ◽  
Time Interval ◽  
Canadian Cordillera ◽  
Plate Convergence ◽  
The North ◽  
Early Tertiary ◽  
Fracture Systems ◽  
North American Craton ◽  
Oceanic Plates

Analyses of Lithoprobe and other data from southwestern Canada provide new insights on how this portion of the Cordillera formed during plate convergence along the western margin of North America. Crustal rocks are detached from their mantle lithosphere, which must have been consumed during subduction. Detachment occurred at or near the base of the crust beneath the Intermontane and (or) Omineca belts, probably along the tips of tectonic wedges while the rocks were still outboard of the relatively cool, mechanically rigid, North American craton. During the Late Cretaceous and early Tertiary, rotation of detached rocks caught between the North American craton and the oceanic plates accounts for some apparently conflicting results between paleomagnetic data that indicate large northward translation of rocks in the western Cordillera, and regional geological features that appear to preclude comparable amounts of translation of rocks in the eastern Cordillera during the same time interval. Transpression associated with rotation in the Foreland and Omineca belts ceased by the early Tertiary because detached allochthonous rocks of the crust became mechanically attached to, and thus physically part of, North America. Continued plate convergence led to regional transtensional shearing and associated crustal extension in the southern Canadian Cordillera, and perhaps as far inboard as northern Montana, where coeval magmatism was probably associated with new, or reactivation of ancient, lithosphere-penetrating fracture systems.

The occurrence of the brachiopods Nanukidium and Atrypoidea in the Late Silurian of southeastern Alaska, Alexander terrane

1989 ◽  
Vol 63 (4) ◽  
pp. 530-533 ◽  
Author(s):  
Norman M. Savage
Keyword(s):  
North America ◽  
North American ◽  
Canadian Arctic ◽  
The North ◽  
Middle Paleozoic ◽  
History Of ◽  
North American Craton ◽  
Alexander Terrane

Previously described faunas of Early Silurian through Late Pennsylvanian age from the Alexander terrane have been endemic, or have variously suggested North American or Asiatic affinities, leaving the paleogeographic history of the terrane uncertain although indicating a location closer to North America than to Asia (Armstrong, 1970; Douglass, 1971; Savage, 1981, 1985, 1989; Savage et al., 1978; Savage and Barkeley, 1985; Soja, 1988; Vaskey, 1982). The occurrence reported here of the Canadian Arctic brachiopods Nanukidium cf. N. cunninghamensis and Atrypoidea scheii in the Alexander terrane during the Late Silurian could be additional evidence supporting the view that the Alexander terrane was not far removed from the North American craton during middle Paleozoic time.

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