Cache Creek Terrane

Cache Creek Terrane
Name	Cache Creek Terrane
Type	Terrane
Region	British Columbia, Yukon, Alaska
Coordinates	58°N 126°W
Age	Paleozoic–Mesozoic
Lithology	Carbonate, chert, basalt, shale, turbidite
Named for	Cache Creek, British Columbia
Country	Canada, United States

Cache Creek Terrane The Cache Creek Terrane is an accreted assemblage of oceanic and continental fragments exposed in western British Columbia, Yukon, and parts of Alaska that records complex interactions among ancient plates including the Farallon Plate, Kula Plate, and continental margins such as Laurentia and Stikine Terrane. Work by investigators from institutions including the Geological Survey of Canada, US Geological Survey, University of British Columbia, Simon Fraser University, and University of Alaska Fairbanks has emphasized its role in Cordilleran tectonics, paleobiogeography, and mineral exploration.

Geologic Overview

The terrane comprises mélanges, oceanic plateau basalts, pelagic carbonates, and cherts that juxtapose with continental shelf assemblages along sutures recognized in maps by the British Columbia Geological Survey and compilations of the Canadian Cordillera. Structural studies linked to researchers at Stanford University, University of Washington, and University of California, Berkeley describe imbrication, thrusting, and strike-slip displacement related to direction changes in plate motions tracked by magnetic anomaly correlations with the Pacific Plate reconstructions and paleomagnetic studies from the Paleomagnetic Laboratory at Oregon State University.

Stratigraphy and Lithology

Stratigraphic columns show an alternation of radiolarian chert, pelagic limestone, submarine basaltic flows, and turbiditic flysch with intercalated olistostromes mapped by teams from Mount Royal University, University of Victoria, and the University of Calgary. Key lithologies include massive carbonate platforms correlated with the Permian and Triassic carbonate sequences, radiolarian-rich chert beds dated alongside conodont assemblages studied at the Smithsonian Institution, Royal Ontario Museum, and the Burke Museum. Detailed petrographic work by laboratories at McGill University and Dalhousie University documents pillow basalts, greenstone alteration, and siliceous sedimentary fabrics.

Tectonic History and Paleogeography

Interpretations place the terrane as an exotic oceanic block accreted during the Mesozoic-Cenozoic orogeny driven by the subduction of the Farallon Plate and later interactions with the Kula Plate and transform motions along the proto-Pacific Plate margin. Models by paleotectonicists associated with Yale University, Princeton University, and the Jet Propulsion Laboratory invoke closure of a back-arc basin and collision against the continental margin of Laurentia near sutures correlated with the Fyfe Fault and the Hackett River Fault analogs. Paleogeographic reconstructions incorporate biogeographic links to the Panthalassa Ocean and to terranes such as the Wrangellia Terrane and the Alexander Terrane.

Paleontology and Fossil Assemblages

Fossil content includes pelagic radiolarians, conodonts, bivalves, and rare ammonoids recognized by paleontologists at the Natural History Museum, London, Canadian Museum of Nature, and Royal BC Museum. Biostratigraphic zonations referencing work at Ohio State University, University of Tennessee, and University of Kansas have refined age assignments from the Devonian through the Triassic by correlating assemblages with repositories at the Field Museum and the American Museum of Natural History. Fossil evidence supports deep-marine depositional environments and affinities with Panthalassic faunas, complementing macrofossil studies undertaken by researchers at the University of California, Los Angeles and the University of Southern California.

Mineralization and Economic Geology

The terrane hosts polymetallic occurrences including Cypress-style volcanogenic massive sulfide prospects, occurrences of copper, zinc, gold, and platinum-group elements documented in assessment reports by the British Columbia Ministry of Energy, Mines and Low Carbon Innovation and by the Yukon Geological Survey. Exploration by junior companies alongside majors such as Teck Resources and consulting groups using geophysical surveys from Geotech Ltd. and geochemical programs at ALS Global has targeted stratabound sulfide lenses, chromite in ultramafic slivers, and placer gold downstream of terrane exposures. Mineral deposit models draw on analogs from the Barite Belt and the Kuroko deposits.

Geochronology and Radiometric Data

Detrital zircon U-Pb geochronology from sedimentary components and SHRIMP and LA-ICP-MS analyses from volcanic and plutonic rocks by labs at American Geophysical Union-affiliated institutions, Geological Survey of Canada facilities, Arizona State University, and University of Melbourne have produced ages spanning Paleozoic to Mesozoic intervals. Metamorphic isotopic systems including Rb-Sr, Sm-Nd, and Ar-Ar studies undertaken at the University of Toronto and Massachusetts Institute of Technology constrain timing of peak metamorphism and cooling during accretionary events correlated with regional thermochronology studies from the Pacific Centre for Isotopic and Geochronological Research.

Regional Correlations and Mapping Studies

Regional mapping conducted by teams from the British Columbia Ministry of Energy, Mines and Low Carbon Innovation, the Geological Survey of Canada, and academic collaborations with Carleton University and Queen's University correlate Cache Creek exposures with equivalent oceanic assemblages in the Intermontane Belt and with fragments identified in the Alaska Range and the Coast Mountains. Integrated synthesis papers in journals such as Geology (journal), Tectonics (journal), and Canadian Journal of Earth Sciences by international coauthors from ETH Zurich, University of Tokyo, and Uppsala University provide updated tectonostratigraphic frameworks and GIS compilations used in modern resource and hazard assessments.

Category:Geology of British Columbia Category:Terranes