J 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

Štítky

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.