Tectonic and Geodynamic Settings of Formation of the Mesozoic Cumulative Dunite–Wehrlite–Olivine Clinopyroxenite—Gabbro Massif in Eastern Chukotka. / Ledneva, G. V.; Bazylev, B. A.; Layer, P. et al.
In: Geotectonics, Vol. 54, No. 4, 01.07.2020, p. 455-476.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Tectonic and Geodynamic Settings of Formation of the Mesozoic Cumulative Dunite–Wehrlite–Olivine Clinopyroxenite—Gabbro Massif in Eastern Chukotka
AU - Ledneva, G. V.
AU - Bazylev, B. A.
AU - Layer, P.
AU - Kuzmin, D. V.
AU - Kononkova, N. N.
N1 - Funding Information: The research was supported by the Russian Science Foundation (grant no. 20-17-00197), by the budget state research projects (nos. 0135-2019-0078 and 0137-2019-0012) and by the state research projects for the Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences. Publisher Copyright: © 2020, Pleiades Publishing, Inc. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2020/7/1
Y1 - 2020/7/1
N2 - The dunite–wehrlite–clinopyroxenite–gabbro massif in Eastern Chukotka, a key object for geodynamic reconstructions of the Vel’may terrane, which represents one of the segments of the southern border of the Chukotka folded system (Chukotka microcontinent, or Arctic Alaska–Chukotka microplate), is investigated. Mineralogical and petrological–geochemical studies of rocks of this massif are carried out. A comparative analysis of the primary mineralogy and formation conditions of cumulative rocks of dunite–wehrlite–pyroxenite–gabbro assemblages from modern island-arc systems, mantle transition zones, and crustal sections of ophiolites and ancient island arcs shows that the rocks studied are cumulates crystallized from a tholeiitic melt in an intraoceanic island arc at a moderately high pressure. The 40Ar/39Ar age of magnesian hornblende from gabbro indicates the massif was formed no later than in the Early–Middle Jurassic. The petrological and geochemical modeling suggests that the analyzed olivine clinopyroxenites and gabbros are probable plutonic comagmates of the Late Triassic island-arc basalts and dolerites of the Vel’may terrane. The arc segment represented by these rocks of the Vel’may terrane was probably part of the system of island arcs which had been reconstructed in this region for the age interval of 163 to 230 Ma. In addition, there is a tendency for the rejuvenation of the Middle Triassic–Late Jurassic island-arc magmatism in the direction from west to east, namely, from the South Anyui terrane of Western Chukotka through the Vel’may terrane of Eastern Chukotka to the Angayucham terrain of Alaska.
AB - The dunite–wehrlite–clinopyroxenite–gabbro massif in Eastern Chukotka, a key object for geodynamic reconstructions of the Vel’may terrane, which represents one of the segments of the southern border of the Chukotka folded system (Chukotka microcontinent, or Arctic Alaska–Chukotka microplate), is investigated. Mineralogical and petrological–geochemical studies of rocks of this massif are carried out. A comparative analysis of the primary mineralogy and formation conditions of cumulative rocks of dunite–wehrlite–pyroxenite–gabbro assemblages from modern island-arc systems, mantle transition zones, and crustal sections of ophiolites and ancient island arcs shows that the rocks studied are cumulates crystallized from a tholeiitic melt in an intraoceanic island arc at a moderately high pressure. The 40Ar/39Ar age of magnesian hornblende from gabbro indicates the massif was formed no later than in the Early–Middle Jurassic. The petrological and geochemical modeling suggests that the analyzed olivine clinopyroxenites and gabbros are probable plutonic comagmates of the Late Triassic island-arc basalts and dolerites of the Vel’may terrane. The arc segment represented by these rocks of the Vel’may terrane was probably part of the system of island arcs which had been reconstructed in this region for the age interval of 163 to 230 Ma. In addition, there is a tendency for the rejuvenation of the Middle Triassic–Late Jurassic island-arc magmatism in the direction from west to east, namely, from the South Anyui terrane of Western Chukotka through the Vel’may terrane of Eastern Chukotka to the Angayucham terrain of Alaska.
KW - Chukotka
KW - cumulative gabbro
KW - cumulative ultramafites
KW - Island arc
KW - subduction geodynamic settings
KW - Vel’may terrane
KW - SPREADING RIDGE
KW - Vel'may terrane
KW - HIGH-PRESSURE ULTRAMAFICS
KW - PEKULNEY COMPLEX
KW - GODZILLA MEGAMULLION
KW - ISLANDS OPHIOLITE
KW - LOWER CRUSTAL ROCKS
KW - TITANIAN PARGASITE
KW - ARM MOUNTAIN MASSIF
KW - OCEANIC CORE COMPLEX
KW - CHROMIAN SPINEL
UR - http://www.scopus.com/inward/record.url?scp=85091316724&partnerID=8YFLogxK
U2 - 10.1134/S0016852120040068
DO - 10.1134/S0016852120040068
M3 - Article
AN - SCOPUS:85091316724
VL - 54
SP - 455
EP - 476
JO - Geotectonics
JF - Geotectonics
SN - 0016-8521
IS - 4
ER -
ID: 25688487