Cretaceous mid-crustal metamorphism and exhumation of the Koolen gneiss dome, Chukotka Peninsula, northeastern Russia

Akinin, V. V.; Calvert, Andrew T.

doi:10.1130/0-8137-2360-4.147

Cited by 24 publications

(15 citation statements)

References 25 publications

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“…The earliest occurrence of high-grade metamorphism is challenging to identify and date in the Kigluaik and Bendeleben Mountains ( Fig. 6), where multiple pulses of Early and Late Cretaceous magmatism and metamorphism complicate the effort (Amato et al, 1994;Akinin and Calvert, 2002;Gottlieb, 2008). Earliest-formed metamorphic assemblages in amphibolite-facies rocks of the Bendeleben Mountains contain kyanite and staurolite (Gottlieb, 2008).…”

Section: Arctic Alaskamentioning

confidence: 99%

A synthesis of Jurassic and Early Cretaceous crustal evolution along the southern margin of the Arctic Alaska–Chukotka microplate and implications for defining tectonic boundaries active during opening of Arctic Ocean basins

Till

2016

Lithosphere

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A synthesis of Late Jurassic and Early Cretaceous collision-related metamorphic events in the Arctic Alaska-Chukotka microplate clarifies its likely movement history during opening of the Amerasian and Canada basins. Comprehensive tectonic reconstructions of basin opening have been problematic, in part, because of the large size of the microplate, uncertainties in the location and kinematics of structures bounding the microplate, and lack of information on its internal deformation history. Many reconstructions have treated Arctic Alaska and Chukotka as a single crustal entity largely on the basis of similarities in their Mesozoic structural trends and similar late Proterozoic and early Paleozoic histories. Others have located Chukotka near Siberia during the Triassic and Jurassic, on the basis of detrital zircon age populations, and suggested that it was Arctic Alaska alone that rotated. The Mesozoic metamorphic histories of Arctic Alaska and Chukotka can be used to test the validity of these two approaches. A synthesis of the distribution, character, and timing of metamorphic events reveals substantial differences in the histories of the southern margin of the microplate in Chukotka in comparison to Arctic Alaska and places specific limitations on tectonic reconstructions. During the Late Jurassic and earliest Cretaceous, the Arctic Alaska margin was subducted to the south, while the Chukotka margin was the upper plate of a north-dipping subduction zone or a zone of transpression. An early Aptian blueschist-and greenschist-facies belt records the most profound crustal thickening event in the evolution of the orogen. It may have resulted in thicknesses of 50-60 km and was likely the cause of flexural subsidence in the foredeep of the Brooks Range. This event involved northern Alaska and northeasternmost Chukotka; it did not involve central and western Chukotka. Arctic Alaska and Chukotka evolved separately until the Aptian thickening event, which was likely a result of the rotation of Arctic Alaska into central and western Chukotka. In northeastern Chukotka, the thickened rocks are separated from the relatively little thickened continental crust of the remainder of Chukotka by the oceanic rocks of the Kolyuchin-Mechigmen zone. The zone is a candidate for an Early Cretaceous suture that separated most of Chukotka from northeast Chukotka and Alaska. Albian patterns of magmatism, metamorphism, and deformation in Chukotka and the Seward Peninsula may represent an example of escape tectonics that developed in response to final amalgamation of Chukotka with Eurasia.

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Section: Arctic Alaskamentioning

confidence: 99%

A synthesis of Jurassic and Early Cretaceous crustal evolution along the southern margin of the Arctic Alaska–Chukotka microplate and implications for defining tectonic boundaries active during opening of Arctic Ocean basins

Till

2016

Lithosphere

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“…Mafic magmatism was invoked as the heat source for high-grade metamorphism and melting (Amato et al 1994;Amato andWright 1997, 1998). The Koolen gneiss dome was exhumed during magmatically driven diapiric rise of the high-grade rocks during northsouth extension of the Bering Strait region (BSGFP 1997;Akinin and Calvert 2002).…”

Section: Regional Geologic Settingmentioning

confidence: 99%

Dike swarms on Seward Peninsula, Alaska, and their implications for the kinematics of Cretaceous extension in the Bering Strait region

Amato¹,

Miller²,

Wright³

et al. 2003

Can. J. Earth Sci.

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Late Cretaceous dike swarms on Seward Peninsula, northwestern Alaska, represent the youngest local manifestation of a ~11575 Ma magmatic event in the Bering Strait region. Magmatism accompanied and followed high-grade metamorphism and ductile deformation. A Late Cretaceous extensional tectonic setting for the region is suggested by the thickness and seismic-reflection characteristics of the crust, regional basin development, formation of high-strain tectonites with subhorizontal foliations, bimodal magmatism, and dike swarms. The orientation of the dike swarms is used to address the kinematics of extension. A diabase dike swarm in the Kigluaik Mountains consists of dikes that strike northeast (040°) and dip steeply. Phenocrysts include plagioclase, clinopyroxene, orthopyroxene, and hornblende. Geochemical data indicate that SiO2 ranges from 48% to 56%, and K2O from 1.2% to 4.0%. The dikes are geochemically similar to the mafic to intermediate root of the 90 Ma Kigluaik pluton. Sr- and Nd-isotope data show that initial 87Sr/86Sr ranges from 0.7070 to 0.7077 and initial εNd ranges from 0.85 to 2.90. Field relations and 40Ar/39Ar geochronology bracket the dike ages between 90 and 84 Ma. Diabase dikes in the York Mountains are associated with normal faults that strike eastwest to east-northeast. Dikes in the Bendeleben Mountains are both mafic and felsic, but their orientations are unknown. Alkalic dikes in the Darby Mountains strike 030°050°, similar to those in the Kigluaik Mountains. Regional relationships including the orientation of dikes, normal faults, mineral stretching lineations, and other shear-sense indicators suggest that between 110 and 90 Ma extension on Seward Peninsula was generally oriented northsouth to north-northwestsouth-southeast.

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“…On the Russian side of the Bering Strait, high-grade gneisses are fl anked by variably deformed but little metamorphosed Paleozoic and Mesozoic metasedimentary rocks and thick sections of Cretaceous volcanic and sedimentary rocks of the Okhotsk-Chukotsk volcanic belt (Parfenov and Natal'in, 1977). Amphibolite-facies metamorphic rocks of the gneiss domes were formerly believed to be Precambrian in age (e.g., Belyi, 1964;Shul'diner and Nedomolkin, 1976;Bunker, et al, 1979) but it is now known that metamorphism occurred in the Late Cretaceous, roughly coeval with the formation of the gneiss domes on Seward Peninsula (Bering Strait Geologic Field Party [BSGFP], 1997;Calvert, 1999;Akinin and Calvert, 2002).…”

Section: Regional Geologic Settingmentioning

confidence: 99%

Geologic map and summary of the evolution of the Kigluaik Mountains gneiss dome, Seward Peninsula, Alaska

Amato¹,

Miller²

2004

Gneiss Domes in Orogeny

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Geologic mapping of the Kigluaik gneiss dome on Seward Peninsula, Alaska, was conducted at 1:24,000 scale and compiled with thesis maps and published maps as a colored map covering eight 15″ quadrangles at 1:63,360 scale. The Kigluaik dome consists of an exceptionally well-exposed 15-km-thick structural section of metasedimentary rocks and orthogneisses. A 91 ± 1 Ma upper-amphibolite-to-granulite facies metamorphic event that was syntectonic with gneiss dome fabrics overprints a pre-120 Ma blueschist-to-greenschist facies event. Peak conditions associated with younger metamorphism increase from greenschist facies in the structurally higher rocks of the Nome Group, through biotite, staurolite, sillimanite, and second sillimanite isograds to granulite facies in the rocks of the Kigluaik Group. The high-grade overprint is coeval with mantle-derived magmatism at 90 ± 1 Ma. Mafi c magmatism provided heat for metamorphism and induced partial melting, also enabling fl ow of gneisses. Deformation thinned the crust as the gneiss dome was exhumed, collapsing isograds and juxtaposing rocks that equilibrated at dramatically different structural levels. Lineations in the gneiss dome record a rotation of stretching directions with structural depth. The continuous transition of lineation azimuth and the lack of overprinting relationships indicate orthogonal stretching directions at different structural levels in the gneiss dome during its formation. Based on regional geologic relations, it is likely that the Bering Strait gneiss domes developed within a continental arc that was undergoing extension, probably as the result of rollback of the north-dipping subducting slab along the Pacifi c margin during Late Cretaceous time.

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Cretaceous mid-crustal metamorphism and exhumation of the Koolen gneiss dome, Chukotka Peninsula, northeastern Russia

Cited by 24 publications

References 25 publications

A synthesis of Jurassic and Early Cretaceous crustal evolution along the southern margin of the Arctic Alaska–Chukotka microplate and implications for defining tectonic boundaries active during opening of Arctic Ocean basins

A synthesis of Jurassic and Early Cretaceous crustal evolution along the southern margin of the Arctic Alaska–Chukotka microplate and implications for defining tectonic boundaries active during opening of Arctic Ocean basins

Dike swarms on Seward Peninsula, Alaska, and their implications for the kinematics of Cretaceous extension in the Bering Strait region

Geologic map and summary of the evolution of the Kigluaik Mountains gneiss dome, Seward Peninsula, Alaska

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