scholarly journals Exotic terranes, late Paleozoic to early Mesozoic fossils and circum-Pacific events

1992 ◽  
Vol 6 ◽  
pp. 277-277
Author(s):  
George D. Stanley
Keyword(s):  
Benthic Invertebrate ◽  
Western Pacific ◽  
Late Paleozoic ◽  
The North ◽  
Early Mesozoic ◽  
Marine Fossils ◽  
Show Evidence ◽  
North American Craton ◽  
Invertebrate Fossils ◽  
Oceanic History

In addition to the breakup of Pangea, other major events occurring in the ancient Pacific during late Paleozoic and early Mesozoic time were the development and dispersal of exotic terranes which now characterize large portions of the eastern and western Pacific margins. While the terrane concept made sense out of the geologic crazy quiltwork pattern of these regions, considerable uncertainties still exist concerning terrane origins and their paleogeographic histories. Did terranes of the eastern and western pacific merely border Pangea or did they once exist within far-flung reaches of the ancient Pacific Ocean? Paleontology is now exploring and seeking answers to such issues based on benthic invertebrate fossils.Like examples in the western Pacific rim of Asia, the American Cordillera contains volcanic terranes with fossil content and history quite different from coeval rocks of the adjacent craton. Some terranes may have developed close to ancient North America, but others show evidence of having existed in settings far-removed from the craton. Over time, some terranes could have experienced considerable geographic displacement via tectonic processes (faulting, rift volcanism, seafloor spreading).Many terranes experienced protracted volcanic episodes of oceanic history during Permian and Triassic time. Terrane amalgamations occurred during Triassic and Jurassic time, and later in the Mesozoic were followed by accretion to the North American Craton. Some terranes such as Quesnellia, Cache Creek, Stikine, Wallowa, Eastern Klamath, and Wrangellia yield excellent benthic marine fossils—many of tropical Tethyan derivation, but other fossil assemblages are of mixed paleogeographic affiliations. Two island arc terranes, Stikinia and Wallowa, contribute to evolutionary and biogeographic issues with Triassic and Jurassic, tropical to temperate marine fossils. These include calcareous algae, sponges and corals occurring in reef sequences which can be related to better known examples from Asia and the former Tethys region. Continuing paleontological investigations into fossils from exotic terranes of the Cordilleran region, offer promise in the resolution of late Paleozoic and early Mesozoic circum-Pacific events and in the attainment of unified views of global paleogeography.

Development of late Paleozoic volcanic arcs in the Canadian Cordillera: an example from the Klinkit Group, northern British Columbia and southern Yukon

2003 ◽  
Vol 40 (7) ◽  
pp. 907-924 ◽  
Author(s):  
Renée-Luce Simard ◽  
Jaroslav Dostal ◽  
Charlie F Roots
Keyword(s):  
British Columbia ◽  
North America ◽  
Volcanic Rocks ◽  
Late Paleozoic ◽  
Canadian Cordillera ◽  
Alkali Basalts ◽  
The North ◽  
Pacific Margin ◽  
North American Craton ◽  
Arc Setting

The late Paleozoic volcanic rocks of the northern Canadian Cordillera lying between Ancestral North America to the east and the accreted terranes of the Omineca belt to the west record early arc and rift magmatism along the paleo-Pacific margin of the North American craton. The Mississippian to Permian volcano-sedimentary Klinkit Group extends discontinuously over 250 km in northern British Columbia and southern Yukon. The two stratotype areas are as follows: (1) in the Englishman Range, southern Yukon, the English Creek Limestone is conformably overlain by the volcano-sedimentary Mount McCleary Formation (Lower Clastic Member, Alkali-Basalt Member and Volcaniclastic Member), and (2) in the Stikine Ranges, northern British Columbia, the Screw Creek Limestone is conformably overlain by the volcano-sedimentary Butsih Formation (Volcaniclastic Member and Upper Clastic Member). The calc-alkali nature of the basaltic volcaniclastic members of the Klinkit Group indicates a volcanic-arc setting ((La/Yb)N = 2.77–4.73), with little involvement of the crust in their genesis (εNd = +6.7 to +7.4). Alkali basalts in the Mount McCleary Formation ((La/Yb)N = 12.5–17.8) suggest periodic intra-arc rifting events. Broadly coeval and compositionally similar volcano-sedimentary assemblages occur in the basement of the Mesozoic Quesnel arc, north-central British Columbia, and in the pericratonic Yukon–Tanana composite terrane, central Yukon, suggesting that they all represent pieces of a single long-lived, late Paleozoic arc system that was dismembered prior to its accretion onto Ancestral North America. Therefore, Yukon–Tanana terrane is possibly the equivalent to the basement of Quesnel terrane, and the northern Quesnel terrane has a pericratonic affinity.

A re-examination of the type area of the Devono-Mississippian Cariboo Orogeny, central British Columbia

1981 ◽  
Vol 18 (12) ◽  
pp. 1767-1775 ◽  
Author(s):  
L. C. Struik
Keyword(s):  
British Columbia ◽  
North American ◽  
Volcanic Rocks ◽  
The Other ◽  
Type Locality ◽  
The Third ◽  
The North ◽  
Early Mesozoic ◽  
Type Area ◽  
North American Craton

Three tectonostratigraphic successions are established from remapping of the area near Barkerville and Cariboo River. The first, of Late Proterozoic to Cambrian sediments, was deposited on the shallow to moderately deep platformal shelf west of and derived from the exposed North American craton. The second is an unconformably overlying Ordovician to Permian sequence of sedimentary and volcanic rocks representing a basinal environment with periodic highs. These packages of sediments were deposited on the North American craton and its western transitional extensions. The third succession, composed of oceanic chert and basalt of the Permo-Pennsylvanian Antler Formation, was thrust eastward over the other two during the early Mesozoic. The three successions were folded, faulted, and metamorphosed during the mid-Mesozoic Columbian Orogeny. The Devono-Mississippian Cariboo Orogeny, which was thought to have affected all of the first sequence and part of the second, could not be documented in its type locality. The geology of the Barkerville – Cariboo River area has many similarities with that of Selwyn Basin and Cassiar platform of northern British Columbia and Yukon.

A note on the Quesnel Lake Gneiss, Caribou Mountains, British Columbia

1989 ◽  
Vol 26 (7) ◽  
pp. 1503-1508
Author(s):  
John R. Montgomery ◽  
John V. Ross
Keyword(s):  
British Columbia ◽  
Late Paleozoic ◽  
Structural Studies ◽  
Western Margin ◽  
Metasedimentary Rocks ◽  
The North ◽  
Deformational History ◽  
Isotope Studies ◽  
Caribou Mountains ◽  
North American Craton

The Quesnel Lake Gneiss is one of several large bodies of gneiss emplaced into the westernmost exposure of the Hadrynian to Paleozoic(?) metasedimentary rocks of the Snowshoe Group in the Omineca Belt, central British Columbia. The gneiss has a deformational history comparable to that of its enveloping rocks, and isotope studies indicate that its age of emplacement is Late Devonian to Early Mississippian and that its age of synkinematic metamorphism is mid-Jurassic. From petrochemical analyses and structural studies, we interpret the gneiss as being a late Paleozoic igneous intrusion into the probable western margin of the North American craton.

Subsurface stratigraphy and basin-fill architecture of the late Paleozoic eastern Taos trough, northern New Mexico, U.S.A.

2020 ◽  
Vol 57 (3) ◽  
pp. 149-176
Author(s):  
Nur Uddin Md Khaled Chowdhury ◽  
Dustin E. Sweet
Keyword(s):  
New Mexico ◽  
Sediment Accumulation ◽  
Late Paleozoic ◽  
North Central ◽  
The North ◽  
Basement Rocks ◽  
Basin Geometry ◽  
Deformation Event ◽  
Thrust System ◽  
Basin Fill

The greater Taos trough located in north-central New Mexico represents one of numerous late Paleozoic basins that formed during the Ancestral Rocky Mountains deformation event. The late Paleozoic stratigraphy and basin geometry of the eastern portion of the greater Taos trough, also called the Rainsville trough, is little known because the strata are all in the subsurface. Numerous wells drilled through the late Paleozoic strata provide a scope for investigating subsurface stratigraphy and basin-fill architecture of the Rainsville trough. Lithologic data obtained predominantly from petrophysical well logs combined with available biostratigraphic data from the greater Taos trough allows construction of a chronostratigraphic framework of the basin fill. Isopach- and structure-maps indicate that the sediment depocenter was just east of the El Oro-Rincon uplift and a westerly thickening wedge-shaped basin-fill geometry existed during the Pennsylvanian. These relationships imply that the thrust system on the east side of the Precambrian-cored El Oro-Rincon uplift was active during the Pennsylvanian and segmented the greater Taos trough into the eastern Rainsville trough and the western Taos trough. During the Permian, sediment depocenter(s) shifted more southerly and easterly and strata onlap Precambrian basement rocks of the Sierra Grande uplift to the east and Cimarron arch to the north of the Rainsville trough. Permian strata appear to demonstrate minimal influence by faults that were active during the Pennsylvanian and sediment accumulation occurred both in the basinal area as well as on previous positive-relief highlands. A general Permian decrease in eustatic sea level and cessation of local-fault-controlled subsidence indicates that regional subsidence must have affected the region in the early Permian.

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