Pierwsze datowania bezwzględne (K-Ar) granitoidów Mongolii Zachodniej

Edmund Rutkowski, Jerzy Borucki

Abstract


THE FIRST ABSOLUTE AGE DETERMINATION (K-Ar) OF THE WEST MONGOLIAN GRANITES

The paper presents the results of 26 potassium-argon absolute age determinations of the granitoid rooks occurring in West Mongolia. 23 of these determinations concern the samples taken in the region of Kobdo and 3 are related to those from the Gobi-Altai area. 7 plutonic cycles have been distinguished in the Kobdo region on geological evidence and on age dating as follows: 1 - pre--Riphean cycle, 2 - Riphean cycle (both not dated), 3 - Young Caledonian cycle, from Upper Silurian up to Lower Devonian, approximately 210 mil. years, 4 - Old Hercynian cycle, Upper Devonian, about 360 mil. years, 5 - Middle Hercynian cycle, Upper Carboniferous, about 290-300 mil. years, 6 - Young Hercynian (?) cycle, Lower or Middle Triassic, approximately 210 mil. years, and 7 - Alpine cycle (not dated).


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