Imbricate architecture of the upper Paleozoic to Jurassic oceanic Cache Creek Terrane, central British Columbia

2001 ◽  
Vol 38 (4) ◽  
pp. 495-514 ◽  
Author(s):  
L C Struik ◽  
P Schiarizza ◽  
M J Orchard ◽  
F Cordey ◽  
H Sano ◽  
...  
Keyword(s):  
British Columbia ◽  
Sedimentary Rocks ◽  
Lower Jurassic ◽  
Spreading Ridge ◽  
Oceanic Plateau ◽  
Upper Paleozoic ◽  
Ophiolite Suite ◽  
Minimum Age ◽  
Thrust Sheets ◽  
Oceanic Rocks

Upper Paleozoic to Lower Jurassic oceanic rocks of the Cache Creek Terrane near Fort St. James, in central British Columbia, form a stack of thrust sheets cut by steeply dipping strike-slip faults. Paleontologically dated upper Paleozoic strata include bioclastic shallow-water limestone and ribbon chert. Isotopically dated Permian rocks consist of tonalite sills and stocks and rhyolite flows intercalated with basalt flows. Paleontologically dated lower Mesozoic rocks include greywacke, sandstone, siltstone, argillite, ribbon chert, conglomerate, limestone, and basalt tuff. Trembleur Ultramafite unit of the Cache Creek Complex, in places part of an ophiolite suite, forms thrust sheets and klippen that overlie lower Mesozoic sedimentary rocks. Sedimentological, lithochemical, paleontological, petrological, and textural comparisons with other areas and established models demonstrate that Cache Creek Terrane is an accretionary complex, a structurally stacked assemblage of rocks that originated in diverse and disparate oceanic paleoenvironments. These environments include spreading ridge, oceanic plateau, atoll, trench fill, and possibly arc. Internal imbrication of the terrane is as young as Early Jurassic, as determined from fossil evidence, and the minimum age of obduction of the thrust stack westward onto Stikine Terrane is Middle Jurassic, as determined from dating of a crosscutting pluton. Triassic blueschist and eclogite of Cache Creek Terrane are interpreted to have been primarily uplifted to upper crustal levels during Triassic subduction. Cache Creek Terrane, as a remnant of that subduction process, and caught in the collision between Stikine and Quesnel terranes, marks the position of a lithosphere-scale suture zone, the Pinchi Suture.

Revised stratigraphy of the Takla Group, north-central British Columbia

1977 ◽  
Vol 14 (2) ◽  
pp. 318-326 ◽  
Author(s):  
J. W. H. Monger ◽  
B. N. Church
Keyword(s):  
British Columbia ◽  
Sedimentary Rocks ◽  
Lower Jurassic ◽  
Upper Triassic ◽  
Late Triassic ◽  
North Central ◽  
Volcaniclastic Rocks ◽  
Jurassic Rocks

The Takla Group of north-central British Columbia as originally defined contained volcanic and sedimentary rocks of Late Triassic and Jurassic ages. As redefined herein, it consists of three formations in the McConnell Creek map-area. Lowest is the Dewar Formation, composed of argillite and volcanic sandstone that is largely the distal equivalent of basic flows and coarse volcaniclastic rocks of the Savage Mountain Formation. These formations are overlain by the volcaniclastic, basic to intermediate Moosevale Formation. These rocks are Upper Triassic (upper Karnian and lower Norian). They are unconformably overlain by Lower Jurassic rocks of the Hazelton Group.

The Hozameen fault system and related Coquihalla serpentine belt of southwestern British Columbia

1986 ◽  
Vol 23 (7) ◽  
pp. 1022-1041 ◽  
Author(s):  
G. E. Ray
Keyword(s):  
British Columbia ◽  
Sedimentary Rocks ◽  
Oceanic Island ◽  
Fault System ◽  
Ultramafic Rocks ◽  
Spreading Ridge ◽  
Early Triassic ◽  
Directed Movement ◽  
Serpentine Belt ◽  
Back Arc

The Hozameen Fault of southwestern British Columbia is associated with the Coquihalla serpentine belt and separates two distinct crustal units. Northeast of the fault are greenstones of the Early Triassic (?) Spider Peak Formation, which are unconformably overlain by Jurassic to Cretaceous turbidite and successor basin deposits of the Pasayten Trough. The oldest sedimentary rocks in the trough, the Ladner Group, contain a locally developed basal unit that hosts the Carolin mine gold orebody. Southwest of the fault, the Permian to Jurassic Hozameen Group represents a dismembered ophiolite succession comprising ultramafic rocks of the Petch Creek serpentine belt, overlain in turn by greenstone and chert units. The greenstones in the Hozameen Group and the Spider Peak Formation are geochemically distinguishable; the latter represent sodic, ocean-floor, subalkaline basalts formed in a spreading ridge environment, while the former include both arc tholeiites and oceanic island–seamount subalkaline basalts.Farther west, the major Petch Creek Fault separates the Hozameen Group from the Custer–Skagit Gneiss. This fault is locally associated with the Petch Creek serpentine belt and is considered to be a northern extension of the Ross Lake Fault of Washington State.The rocks in the Hozameen Group, Spider Peak Formation, and Pasayten Trough were probably deposited within a single basin that initiated as an extensive, multirifted, marginal back-arc basin and eventually evolved into the steadily narrowing Pasayten Trough.Following Early to Middle Cretaceous closure of the Pasayten Trough, oblique, easterly-directed movement along westerly-dipping thrusts caused the Custer–Skagit Gneiss to override the Hozameen Group, which in turn overrode rocks of the Pasayten Trough farther east; these boundary thrusts formed precursor structures for the Hozameen and Petch Creek faults. Ultramafic basement material underlying the Spider Peak Formation and the Hozameen Group was thrust up the bounding fractures, producing the Coquihalla and Petch Creek serpentine belts, respectively.Large-scale dextral transcurrent displacement, possibly related to movement along the Fraser Fault system, occurred subsequently along the Petch Creek and Hozameen faults. This wrench movement was preceded by the Mid-Eocene (?) intrusion of the Needle Peak pluton and was followed by emplacement of the 16–35 Ma Chilliwack batholith.

Regional imbrication within Quesnel Terrane, central British Columbia, as suggested by conodont ages

1988 ◽  
Vol 25 (10) ◽  
pp. 1608-1617 ◽  
Author(s):  
L. C. Struik
Keyword(s):  
British Columbia ◽  
North American ◽  
Lower Jurassic ◽  
Thrust Sheet ◽  
Pillow Basalt ◽  
Stacking Order ◽  
Lower Unit ◽  
Upper Paleozoic

Quesnel Terrane, at Quesnel Lake, consists of two regional Triassic–Jurassic age-equivalent units, the Takla–Nicola and Slocan – King Salmon assemblages, as determined from conodonts and macrofossils. The upper mainly volcanic unit (Takla–Nicola) overlies the mainly pelitic unit (Slocan – King Salmon) and was probably emplaced by thrusting. The lower unit consists of dark grey pelite, siltite, limestone, and lesser amounts of fragmental basalt and greywacke. The upper unit consists of fragmental basalt, diorite, greywacke, and lesser amounts of dark grey siltite and pelite and limestone. The unit age and stacking order suggest that during the Jurassic, the volcanic-rich thrust sheet was transported northeastward over an eastern, more pelitic facies of the terrane. The northwesterly trending thrust trace is approximately 300 km long. The Triassic and Lower Jurassic subduction-generated volcanic unit may have been deposited on sediments and volcanics equivalent to the upper Paleozoic Harper Ranch Group; the eastern Triassic and Lower Jurassic pelite unit may have been deposited on the pillow basalt and ribbon chert of the upper Paleozoic Slide Mountain Group. The upper Paleozoic Harper Ranch and Slide Mountain group rocks may have rested on attenuated North American crust.

Geological and geochemical evidence for variable magmatism and tectonics in the southern Canadian Cordillera: Paleozoic to Jurassic suites, Greenwood, southern British Columbia

2001 ◽  
Vol 38 (1) ◽  
pp. 75-90 ◽  
Author(s):  
J Dostal ◽  
B N Church ◽  
T Hoy
Keyword(s):  
British Columbia ◽  
Middle Triassic ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Deep Ocean ◽  
Island Arc ◽  
Canadian Cordillera ◽  
South Central ◽  
Upper Paleozoic ◽  
Paleozoic Rocks

The Paleozoic and early Mesozoic rocks of the Greenwood mining camp in southern British Columbia are a part of the Quesnel terrane in the eastern part of the Intermontane Belt of the Canadian Cordillera. Upper Paleozoic rocks include the Knob Hill Group composed of oceanic tholeiitic basalts (with (La/Yb)n [Formula: see text] 0.4–1.2), associated with deep ocean sedimentary rocks and serpentinites; the Attwood Group that comprises island-arc tholeiites (with (La/Yb)n [Formula: see text] 1–4 and positive εNd values), clastic sedimentary rocks and limestones; and a unit of oceanic gabbros with (La/Yb)n < 0.5. These lithologically defined units occur as tectonically emplaced slivers of oceanic crust probably produced during the closure of the Slide Mountain basin during the Permian. They are unconformably overlain by Middle Triassic calc-alkaline volcanic and sedimentary rocks of the Brooklyn Group. The Brooklyn Group volcanic rocks have characteristics of mature island-arc rocks, including (La/Yb)n [Formula: see text] 2.5–4.5 and positive εNd values. The Paleozoic rocks are crosscut by a 200 million years old granodioritic intrusion containing zircon with an Early Proterozoic inheritance age (~2.4 Ga). By inference, southern Quesnellia may have been well offshore from the ancestral North American margin in the Mississippian, in close proximity to the margin by the Middle Triassic, and contiguous with it by the Early Jurassic. It is suggested that the complex tectonic history of extension and contraction of the southern Canadian Cordillera during the post Middle Jurassic can be extended in south-central British Columbia as far back as the upper Paleozoic.

Bridge River tephra: revised distribution and significance for detecting old carbon errors in radiocarbon dates of limnic sediments in southern British Columbia

1980 ◽  
Vol 17 (11) ◽  
pp. 1454-1461 ◽  
Author(s):  
Rolf W. Mathewes ◽  
John A. Westgate
Keyword(s):  
British Columbia ◽  
Sedimentary Rocks ◽  
Lacustrine Sediments ◽  
Igneous Rocks ◽  
The South ◽  
Radiocarbon Dates ◽  
Carbon Contamination ◽  
Horseshoe Lake ◽  
Tephra Beds

Ash-grade Bridge River tephra, identified as such on the basis of shard habit, modal mineralogy, and composition of ilmenite, occurs in sedimentary cores from three lakes located to the south of the previously documented plume and necessitates a significant enlargement of the fallout area of that tephra in southwestern British Columbia.These new, more southerly occurrences are probably equivalent to the ~2350 year old Bridge River tephra, although it can be argued from the evidence at hand that the 14C dates and biotite-rich nature support relationship to a slightly earlier Bridge River event.Large differences exist in the 14C age of sediments immediately adjacent to the Bridge River tephra at these three lake sites; maximum ages of 3950 ± 170 years BP (GX-5549) and 3750 ± 210 years BP (I-10041) were obtained at Phair and Fishblue lakes, respectively, whereas the corresponding age at Horseshoe Lake is only 2685 ± 180 years BP (GX-5757). The two older dates are considered to be significantly affected by old carbon contamination for the bedrock locally consists of calcareous sedimentary rocks and the lacustrine sediments are very calcareous. The 14C date from Horseshoe Lake, which occurs in an area of igneous rocks, appears to be only slightly too old relative to the ~2350 year old Bridge River tephra.Well-dated tephra beds, therefore, can be very useful in assessing the magnitude of old carbon errors associated with radiocarbon dates based on limnic sediments. Calcareous gyttja deposits beneath Bridge River tephra within the study area exhibit old carbon errors of the order of 1350–1550 years.

Provenance of Jurassic sedimentary rocks of south-central Quesnellia, British Columbia: implications for paleogeography

2004 ◽  
Vol 41 (1) ◽  
pp. 103-125 ◽  
Author(s):  
Nathan T Petersen ◽  
Paul L Smith ◽  
James K Mortensen ◽  
Robert A Creaser ◽  
Howard W Tipper
Keyword(s):  
Detrital Zircon ◽  
Middle Jurassic ◽  
Sedimentary Rocks ◽  
Source Area ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Late Triassic ◽  
Nd Isotopes ◽  
South Central ◽  
History Of

Jurassic sedimentary rocks of southern to central Quesnellia record the history of the Quesnellian magmatic arc and reflect increasing continental influence throughout the Jurassic history of the terrane. Standard petrographic point counts, geochemistry, Sm–Nd isotopes and detrital zircon geochronology, were employed to study provenance of rocks obtained from three areas of the terrane. Lower Jurassic sedimentary rocks, classified by inferred proximity to their source areas as proximal or proximal basin are derived from an arc source area. Sandstones of this age are immature. The rocks are geochemically and isotopically primitive. Detrital zircon populations, based on a limited number of analyses, have homogeneous Late Triassic or Early Jurassic ages, reflecting local derivation from Quesnellian arc sources. Middle Jurassic proximal and proximal basin sedimentary rocks show a trend toward more evolved mature sediments and evolved geochemical characteristics. The sandstones show a change to more mature grain components when compared with Lower Jurassic sedimentary rocks. There is a decrease in εNdT values of the sedimentary rocks and Proterozoic detrital zircon grains are present. This change is probably due to a combination of two factors: (1) pre-Middle Jurassic erosion of the Late Triassic – Early Jurassic arc of Quesnellia, making it a less dominant source, and (2) the increase in importance of the eastern parts of Quesnellia and the pericratonic terranes, such as Kootenay Terrane, both with characteristically more evolved isotopic values. Basin shale environments throughout the Jurassic show continental influence that is reflected in the evolved geochemistry and Sm–Nd isotopes of the sedimentary rocks. The data suggest southern Quesnellia received material from the North American continent throughout the Jurassic but that this continental influence was diluted by proximal arc sources in the rocks of proximal derivation. The presence of continent-derived material in the distal sedimentary rocks of this study suggests that southern Quesnellia is comparable to known pericratonic terranes.

The Lower Jurassic phosphorites of southeastern British Columbia and terrane accretion to western North America

1989 ◽  
Vol 26 (8) ◽  
pp. 1612-1616 ◽  
Author(s):  
T. P. Poulton ◽  
J. D. Aitken
Keyword(s):  
British Columbia ◽  
North America ◽  
Oceanic Crust ◽  
West Coast ◽  
Cold Water ◽  
Lower Jurassic ◽  
Depositional Model ◽  
Western North America ◽  
The West ◽  
Terrane Accretion

Sinemurian phosphorites in southeastern British Columbia and southwestern Alberta conform with the "West Coast type" phosphorite depositional model. The model indicates that they were deposited on or near the Early Jurassic western cratonic margin, next to a sea or trough from which cold water upwelled. This suggests that the allochthonous terrane Quesnellia lay well offshore in Sinemurian time. The sea separating Quesnellia from North America was partly floored by oceanic crust ("Eastern Terrane") and partly by a thick sequence of rifted, continental terrace wedge rocks comprising the Purcell Supergroup and overlying Paleozoic sequence. This sequence must have been depressed sufficiently that access of upwelling deep currents to the phosphorite depositional area was not impeded.

New Lower Jurassic ammonite faunas from the Fernie Formation, southern Canadian Rocky Mountains

1987 ◽  
Vol 24 (8) ◽  
pp. 1688-1704 ◽  
Author(s):  
Russell L. Hall
Keyword(s):  
British Columbia ◽  
North American ◽  
Rocky Mountains ◽  
Red Deer ◽  
First Record ◽  
Lower Jurassic ◽  
Canadian Rocky Mountains ◽  
Poker Chip

New ammonite faunas are described from sections along Bighorn and Scalp creeks in central-western Alberta where Lower Jurassic parts of the Fernie Formation are exposed. The first record of the upper Sinemurian Obtusum Zone from the Fernie is based on the occurrence of Asteroceras cf. stellare and Epophioceras cf. breoni in the basal pebbly coquina on Bighorn Creek. The overlying Red Deer Member has yielded Amaltheus cf. stokesi, representing the upper Pliensbachian Margaritatus Zone; in immediately superjacent strata the first North American examples of ?Amauroceras occur together with Protogrammoceras and ?Aveyroniceras. In the basal parts of the overlying Poker Chip Shale a fauna including Harpoceras cf. falciferum, Harpoceratoides, Polyplectus cf. subplanatus, Hildaites cf. serpentiniformis, and Dactylioceras cf. athleticum is correlated with the lower Toarcian Falciferum Zone.The upper parts of the Poker Chip Shale on Fording River in southeastern British Columbia contain a fauna representing some part of the upper Toarcian, but owing to poor preservation, generic identifications are only tentatively made.

A Lower Jurassic heteroporid bryozoan and associated biota, Turnagain Lake, British Columbia

1981 ◽  
Vol 18 (3) ◽  
pp. 457-468 ◽  
Author(s):  
C. M. Henderson ◽  
D. G. Perry
Keyword(s):  
British Columbia ◽  
North America ◽  
Green Alga ◽  
Marine Environment ◽  
High Energy ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Associated Fauna ◽  
North Central ◽  
Commensal Relationship

Late Early Jurassic heteroporid bryozoa occur in arenaceous carbonates near Turnagain Lake, north-central British Columbia. The occurrence of Heteropora tipperi n. sp. marks the first documentation of Early Jurassic cyclostome bryozoa in North America. The associated fauna, comprising the ammonite Harpoceras, the foraminifer Reinholdella, and the pelecypod Weyla, establish the age as Early Toarcian. Other associated biota include an endolithic green alga(e), which is demonstrated to have a commensal relationship with H. tipperi n. sp. Sedimentologic and biotic data from the host strata point to a shallow, temperate, high-energy, normal marine environment.

scholarly journals Ngwevu intloko: a new early sauropodomorph dinosaur from the Lower Jurassic Elliot Formation of South Africa and comments on cranial ontogeny in Massospondylus carinatus

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7240 ◽  
Author(s):  
Kimberley E.J. Chapelle ◽  
Paul M. Barrett ◽  
Jennifer Botha ◽  
Jonah N. Choiniere
Keyword(s):  
South Africa ◽  
New Species ◽  
Sexual Dimorphism ◽  
New Genus ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Adult Size ◽  
Minimum Age ◽  
Cranial Ontogeny ◽  
Morphological Differences

Our knowledge of Early Jurassic palaeobiodiversity in the upper Elliot Formation of South Africa has increased markedly in recent years with the discovery of new fossils, re-assessments of previously collected material and a better understanding of Stormberg Group stratigraphy. Here, Ngwevu intloko, a new genus of upper Elliot basal sauropodomorph is named on the basis of a complete skull and partial skeleton (BP/1/4779) previously assigned to Massospondylus carinatus. It can be distinguished from all other basal sauropodomorphs by a combination of 16 cranial and six postcranial characters. The new species is compared to a small ontogenetic series of M. carinatus as well as to a range of closely related taxa. Taphonomic deformation, sexual dimorphism and ontogeny are rejected as possible explanations for the morphological differences present between BP/1/4779 and other taxa. Osteohistological examination reveals that BP/1/4779 had nearly reached adult size at the time of its death at a minimum age of 10 years.

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