2016
The Kabul Block (Afghanistan), a segment of the Columbia Supercontinent, with a Neoproterozoic metamorphic overprint
FARYAD, Shah Wali, Stephen COLLETT, Fritz FINGER, Sergey A SERGEEV, Renata ČOPJAKOVÁ et. al.Základní údaje
Originální název
The Kabul Block (Afghanistan), a segment of the Columbia Supercontinent, with a Neoproterozoic metamorphic overprint
Autoři
FARYAD, Shah Wali (203 Česká republika, garant), Stephen COLLETT (250 Francie), Fritz FINGER (40 Rakousko), Sergey A SERGEEV (643 Rusko), Renata ČOPJAKOVÁ (203 Česká republika, domácí) a Pavol SIMAN (703 Slovensko)
Vydání
Gondwana Research, AMSTERDAM, Elsevier, 2016, 1342-937X
Další údaje
Jazyk
angličtina
Typ výsledku
Článek v odborném periodiku
Obor
10500 1.5. Earth and related environmental sciences
Stát vydavatele
Nizozemské království
Utajení
není předmětem státního či obchodního tajemství
Impakt faktor
Impact factor: 6.959
Kód RIV
RIV/00216224:14310/16:00094064
Organizační jednotka
Přírodovědecká fakulta
UT WoS
000384702600015
Klíčová slova anglicky
Kabul Block; Neoarchean orthogneiss; Paleoproterozoic and Neoproterozoic orogenies
Změněno: 14. 4. 2017 14:53, Ing. Andrea Mikešková
Anotace
V originále
We report field relationships, petrography and isotopic ages from two superposed basement units of the Kabul Block, the so called Lower Sherdarwaza and Upper Welayati formations. The Sherdarwaza Formation is represented mostly by migmatites and gneisses that are derived from pelitic and psammitic lithologies with lenses and layers of mafic and carbonate rocks. Several bodies of orthogneisses are also exposed in the Sherdarwaza Formation. The Upper Welayati Formation is characterized by micaschist, quartzite and amphibolites. SHRIMP U-Pb data on zircon from the orthogneiss in the Sherdarwaza Formation indicates a Neoarchean age of ca 25-2.8 Ga for their magmatic crystallization. The rocks exhibit granulite facies conditions of 5-7 kbar and 800 degrees C that are documented by the presence of orthopyroxene and Ti-rich biotite in the orthogneiss and by olivine and phlogopite in some talc-silicate rocks at contact with marble. A Paleoproterozoic age of ca. 1.85-1.80 Ga for this metamorphism was obtained using U-Pb SHRIMP dating on zircon and U-Th dating on monazite. Mineral textural relations also show a younger amphibolite facies metamorphism that is documented in both the Sherdarwaza and Welayati formations. This metamorphism occurred at relatively higher pressure conditions of up to 9 kbar at ca. 650 degrees C, compared to the granulite facies event. A Neoproterozoic age of ca 0.85-0.9 Ga, for this metamorphism is confirmed by Ar-Ar data on biotite and white mica as well as by U-Th data on monazite. By combining the presented results on the metamorphic petrology, geochronology and geochemistry, we conclude that: (1) The Kabul basement is a fragment of an Archean block (craton); (2) the ca. 1.85-1.8 and 0.9-0.85 Ga metamorphism marks an important orogenic events for the basement rocks of the Kabul Block which was stabilized during the early Precambrian; (3) the two metamorphic ages correlate well with global-scale orogenies related to the assembly of the Paleoproterozoic Columbia and Neoproterozoic Rodinia supercontinents; (4) based on metamorphic characteristics and ages, the Kabul basement rocks show an affinity to the Neoarchean rocks of the Tarim and/or South China cratons. (C) 2015 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.