Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: Central Asian Orogenic Belt

Sortuj według:

Ogranicz wyniki do:

Zastosowanie metody K-Ar do oznaczenia wieku deformacji skał metaosadowych formacji Yargait terranu Zavkhan (Khasagt, Mongolia) : wstępne wyniki badań

Sikora Rafał, Wójcik Antoni, Szczerba Marek, Bazarnik Jakub, Madej Stanisław

Przegląd Geologiczny

2021

Vol. 69, nr 7

448--453

The SW margin of the Zavkhan terrane is significant for research on Paleozoic amalgamation of the Central Asian Orogenic Belt (CAOB). The study area is located in the western part of the Khasagt Mountains, western Mongolia. We present a new preliminary K-Ar dating of metasedimentary rocks from the Yargait Formation which were deformed during collision of the Zavkhan terrane with the Lake Zone terrane. Our results include two dating that are similar to earlier data by other authors (Stípskáetal., 2010; Bold et al., 2016b). The first dating equal to 544.1 ±13.7 Ma can be interpreted as the age ofmetamorphism and the subduction of the SW margin ofthe Zavkhan terrane under the Lake Zone terrane during the late Ediacaran-early Cambrian. The second dating of 441.1 ±11.7 Ma indicates the Late Ordovician - Silurian regional extension event.

Late Ordovician palaeogeography and the positions of the Kazakh terranes through analysis of their brachiopod faunas

Popov L. E., Cocks L. R. M.

Acta Geologica Polonica

2017

Vol. 67, no. 3

323--380

Detailed biogeographical and biofacies analyses of the Late Ordovician brachiopod faunas with 160 genera, grouped into 94 faunas from individual lithotectonic units within the Kazakh Orogen strongly support an archipelago model for that time in that area. The Kazakh island arcs and microcontinents within several separate clusters were located in the tropics on both sides of the Equator. Key units, from which the Late Ordovician faunas are now well known, include the Boshchekul, Chingiz-Tarbagatai, and Chu-Ili terranes. The development of brachiopod biogeography within the nearly ten million year time span of the Late Ordovician from about 458 to 443 Ma (Sandbian, Katian, and Hirnantian), is supported by much new data, including our revised identifications from the Kazakh Orogen and elsewhere. The Kazakh archipelago was west of the Australasian segment of the Gondwana Supercontinent, and relatively near the Tarim, South China and North China continents, apart from the Atashu-Zhamshi Microcontinent, which probably occupied a relatively isolated position on the south-western margin of the archipelago. Distinct faunal signatures indicate that the Kazakh terranes were far away from Baltica and Siberia throughout the Ordovician. Although some earlier terranes had joined each other before the Middle Ordovician, the amalgamation of Kazakh terranes into the single continent of Kazakhstania by the end of the Ordovician is very unlikely. The Late Ordovician brachiopods from the other continents are also compared with the Kazakh faunas and global provincialisation statistically determined.