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TitleGeochronology and structural setting of Latest Devonian - Early Carboniferous magmatic rocks, Cape Kiber, northeast Russia
 
AuthorLane, L SORCID logo; Cecile, M P; Gehrels, G E; Kos'ko, M K; Layer, P W; Parrish, R R
SourceCanadian Journal of Earth Sciences vol. 52, no. 3, 2015 p. 147-160, https://doi.org/10.1139/cjes-2013-0184 Open Access logo Open Access
Image
Year2015
Alt SeriesEarth Sciences Sector, Contribution Series 20120464
PublisherCanadian Science Publishing
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
AreaCape Kiber; Chukotka; Russian Federation
Lat/Long WENS 172.5000 173.0000 70.0000 69.7500
Subjectsgeochronology; structural geology; geochemistry; tectonics; magmatic rocks; uranium lead dates; argon argon dates; petrographic analyses; deformation; geochemical analyses; igneous rocks; granites; major element analyses; trace element analyses; Aptian; Albian; dykes; tectonic setting; magmatism; Carboniferous; Devonian
Illustrationsgeological sketch maps; analyses
ProgramGEM: Geo-mapping for Energy and Minerals Yukon Sedimentary Basins
Released2015 01 15
AbstractCape Kiber on the Arctic coast of Chukotka, northeast Russia, consists of a granite intruding Devonian (and older?) strata in the core of a large southeast trending anticline. These strata are structurally overlain by Carboniferous and younger strata. A U-Pb age of 351.4 ± 5.6 (2s) Ma shows that the granite is Early Carboniferous in age. A large granite cobble extracted from a Carboniferous conglomerate produced a Late Devonian or Early Carboniferous U-Pb age of ~355-361 Ma. Also, a deformed and altered granitic dyke yielded an age of 363.7 ± 5.7 (2s) Ma. Major and trace elements suggest a syn-collisional (orogenic) setting. The granite's (biotite) Ar release spectrum is reset. The granitic dyke also shows a disturbed Ar-Ar whole-rock spectrum implying an Early Cretaceous age (~122-130 Ma) for closure of the Ar system. We interpret this as due to widespread greenschist metamorphism accompanying regional deformation of the Anyuy-Chukotka Fold Belt that accompanied closure of the South Anyuy Ocean. Regionally, this event predates deposition of Aptian and Albian strata and the eruption of Okhotsk-Chukotsk magmatic rocks. An Ar-Ar (biotite) plateau age of 96.4 ± 1.0 (2s) Ma from a mildly deformed, lamprophyre dyke reflects intrusion in a setting of regional extension. Its deformation reflects a younger tectonic event. The record of Devonian-Carboniferous magmatism and early Carboniferous unroofing is younger and less complex than that of Arctic Alaska. However, evidence for Early Devonian (Caledonian) or Late Devonian (Ellesmerian) deformation could have been masked by intense Mesozoic deformation. Outcrop data and geochronology support and refine regional interpretations of Early Cretaceous deformation and mineral growth accompanying accretion of Chukotka to north Asia, followed by regional extension and subsequent convergent deformation.
Summary(Plain Language Summary, not published)
Comparisons of chemistry and age data for granites of similar ages around the Arctic provide important clues to the geological evolution of the Arctic Ocean basins. Up to one-quarter of the world's undiscovered petroleum resources are predicted to occur there. Other governments and major multinational companies are currently spending billions of dollars assessing the region's petroleum potential. These data, collected during a previous scientific exchange with Russia, are compiled and interpreted in this study. The study area in northeastern Russia is remote and poorly accessible to westerners, making these rare data timely and valuable.
GEOSCAN ID292412

 
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