Lower Cambrian Stratigraphic Studies in the Mcbride area, British Columbia (93h)

1969 ◽  
Author(s):  
F G Young
Keyword(s):  
British Columbia ◽  
Lower Cambrian

The initiation of the early Paleozoic Cordilleran miogeocline: evidence from the uppermost Proterozoic – Lower Cambrian Hamill Group of southeastern British Columbia

1988 ◽  
Vol 25 (1) ◽  
pp. 1-19 ◽  
Author(s):  
William J. Devlin ◽  
Gerard C. Bond
Keyword(s):  
British Columbia ◽  
Lower Cambrian ◽  
Direct Evidence ◽  
Thermal Anomaly ◽  
Passive Margin ◽  
Early Paleozoic ◽  
Upper Proterozoic ◽  
Windermere Supergroup ◽  
Depositional Setting ◽  
Thermal Subsidence

The uppermost Proterozoic–Lower Cambrian Hamill Group of southeastern British Columbia contains geologic evidence for a phase of extensional tectonism that led directly to the onset of thermally controlled subsidence in the Cordilleran miogeocline. Moreover, the Hamill Group contains the sedimentological record of the passage of the ancient passive margin from unstable tectonic conditions associated with rifting and (or) the earliest phases of thermal subsidence to post-rift conditions characterized by stabilization of the margin and dissipation of the thermal anomaly generated during the rift phase (the rift to post-rift transition). Widespread uplift that occurred prior to and during the deposition of the lower Hamill Group is indicated by an unconformable relation with the underlying Windermere Supergroup and by stratigraphic relations between Middle and Upper Proterozoic strata and unconformably overlying upper Lower Cambrian quartz arenites (upper Hamill Group) in the southern borderlands of the Hamill basin. In addition, the coarse grain size, the feldspar content, the depositional setting, and the inferred provenance of the lower Hamill Group are all indicative of the activation of basement sources along the margins of the Hamill basin. Geologic relations within the Hamill Group that provide direct evidence for extensional tectonism include the occurrence of thick sequences of mafic metavolcanics and rapid vertical facies changes that are suggestive of syndepositional tectonism.Evidence of extensional tectonism in the Hamill Group directly supports inferences derived from tectonic subsidence analyses that indicate the rift phase that immediately preceded early Paleozoic post-rift cooling could not have occurred more than 10–20 Ma prior to 575 ± 25 Ma. These data, together with recently reported isotopic data that suggest deposition of the Windermere Supergroup began ~730–770 Ma, indicate that the rift-like deposits of the Windermere Supergroup are too old to represent the rifting that led directly to the deposition of the Cambro-Ordovician post-rift strata. Instead, Windermere sedimentation was apparently initiated by an earlier rift event, probably of regional extent, that was part of a protracted, episodic rift history that culminated with continental breakup in the latest Proterozoic – Early Cambrian.

Archaeocyathids and the Lower Cambrian Continental Shelf of the Canadian Cordillera

1975 ◽  
Vol 12 (12) ◽  
pp. 2014-2020 ◽  
Author(s):  
C. R. Stelck ◽  
A. S. Hedinger
Keyword(s):  
British Columbia ◽  
Continental Shelf ◽  
Lower Cambrian ◽  
Rocky Mountain ◽  
Canadian Cordillera ◽  
Western Canada ◽  
Early Cambrian ◽  
Structural Trend ◽  
East And West

The geographic occurrences of archaeocyathids are plotted for the Cordilleran region of western Canada. The archaeocyathids are found both east and west of, and within the Rocky Mountain Trench in British Columbia and are found east and west of the Tintina Trench in the southern Yukon. The overall pattern of the occurrences indicates that the shallow neritic portion of the continental shelf in Early Cambrian time traces a pattern widely diverse from that of the later, superimposed, Laramide structural trend. Portions of the continental shelf were already in existence west of the Rocky Mountain Trench by Early Cambrian time.

Lower Cambrian pediculate lingulids from Yunnan, China

1993 ◽  
Vol 67 (5) ◽  
pp. 788-798 ◽  
Author(s):  
Jin Yugan ◽  
Hou Xianguang ◽  
Wang Huayu
Keyword(s):  
New York ◽  
British Columbia ◽  
Lower Cambrian ◽  
Structure And Function ◽  
The Other ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
Middle Ordovician ◽  
Early Ordovician ◽  
And Function

The vermiform pedicle is one of the most distinctive organs of modern lingulids, but it is rarely preserved. Only two fossil specimens of lingulids with pedicle casts have been reported, one from the Ordovician and the other from the Devonian. No record of fossil pedicles of Lingulella and Lingulepis, the dominant Cambrian and Early Ordovician lingulids, is known. Fossil lingulids from the Lower Cambrian of Chengjiang County, Yunnan, suggest that the structure and function of the pedicle of the lingulids has not changed significantly from its first appearance. A comparison of fossil pedicle of lingulids from the Lower Cambrian, Chengjiang County (China), the Burgess Shale, Middle Cambrian, British Columbia (Canada), the Trenton Formation, Middle Ordovician, New York (U.S.A.), and the Devonian, Devonshire (England, U.K.) shows that the delthyrial area to which the pedicle muscles are attached was reduced in length through time until these muscles were completely embraced by the two valves.Two species, Lingulella chengjiangensis n. sp. and Lingulepis malongensis Rong, are described.

Cambrian Lagerstätten: their distribution and significance

1985 ◽  
Vol 311 (1148) ◽  
pp. 49-65 ◽  
Keyword(s):  
British Columbia ◽  
Special Reference ◽  
Community Ecology ◽  
Lower Cambrian ◽  
South Australia ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
Upper Cambrian ◽  
Exceptional Preservation ◽  
Biotic Diversity

The geological setting, biotic diversity and taphonomy of Cambrian soft-bodied Lagerstätten are reviewed with special reference to the Lower Cambrian Emu Bay Shale (South Australia) and Kinzers Formation (Pennsylvania), and the Middle Cambrian Stephen Formation (Burgess Shale and adjacent localities, British Columbia). Brief mention is made also of a number of more minor occurrences in the U.S.A., China and Spain. Exceptional preservation in the Upper Cambrian is discussed by K. J. Müller (this symposium). These soft-bodied Lagerstätten afford a series of special insights into the nature of Cambrian life. Emphasis is laid on the information they provide with regards (i) levels of diversity and the proportion of skeletized taxa; (ii) the origin and relative success of bodyplans; (iii) community ecology and evolution.

Lower and Early Middle Cambrian Formations near Mount Robson, British Columbia and Alberta

1975 ◽  
Vol 12 (2) ◽  
pp. 119-131 ◽  
Author(s):  
W. H. Fritz ◽  
E. W. Mountjoy
Keyword(s):  
British Columbia ◽  
Lower Cambrian ◽  
Middle Cambrian ◽  
Physical Evidence ◽  
Control Section ◽  
Middle Unit

Five formations and part of a sixth were examined in order to resolve conflicting reports as to their age and lateral relationship. The formations are redescribed at their type sections and equivalent strata are described at a control section. It is concluded that the Lower Cambrian Mural, Mahto, and Hota Formations and the Middle Cambrian Chetang Formation are valid and that the Tah (= Mural) and Adolphus (= Hota) Formations should be suppressed. The boundary between the Nevadella and Bonnia-Olenellus Zone falls within the middle unit of the Mural. The Lower – Middle Cambrian boundary is located at or very near the contact between the Hota and overlying Chetang Formation. This is a sharp lithologic contract, but no physical evidence of an unconformity was noted.

New Lower Cambrian olenelloid trilobite genera Cirquella and Geraldinella from southwestern Canada

1993 ◽  
Vol 67 (5) ◽  
pp. 856-868 ◽  
Author(s):  
W. H. Fritz
Keyword(s):  
British Columbia ◽  
Rocky Mountains ◽  
Lower Cambrian ◽  
Type Species ◽  
Canadian Rocky Mountains

The genus Cirquella is erected for small, smooth nevadiid trilobites that lack genal spines. The type species, C. nummularia, is associated with taxa in the Dogtooth Mountains, British Columbia, that belong to the Nevadella Zone. A second species, C. espinata, is described from the southern Canadian Rocky Mountains, where it is associated with the new archaeaspid genus Geraldinella. Strata in the latter locality can be physically correlated to documented strata of the Nevadella Zone. The same zone in Nevada contains C. nummularia?.

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