TY - JOUR

T1 - The Age of Rift-Related Basalts in East Antarctica

AU - Leitchenkov, G. L.

AU - Belyatsky, B. V.

AU - Kaminsky, V. D.

PY - 2018/1

Y1 - 2018/1

N2 - The Lambert Rift, which is a large intracontinental rift zone in East Antarctica, developed over a long period of geological time, beginning from the Late Paleozoic, and its evolution was accompanied by magmatic activity. The latest manifestation of magmatism is eruption of alkaline olivine–leucite basalts on the western side of the Lambert Rift; Rb–Sr dating referred its time to the Middle Eocene, although its genesis remained vague. In order to solve this problem, we found geochronometer minerals in basaltic samples and 68 apatite grains appeared to be suitable for analysis. Their ages and ages of host basalts, determined by the U–Pb local method on the SIMS SHRIMP-II, were significantly different (323 ± 31 Ma) from those assumed earlier. This age corresponds to the earliest stage of crustal extension in East Antarctica and to most of Gondwana. The new data crucially change the ideas about the evolution of Lambert Rift and demonstrate the ambiguity of К–Ar dates of the alkali effusive formed under long-term rifting.

AB - The Lambert Rift, which is a large intracontinental rift zone in East Antarctica, developed over a long period of geological time, beginning from the Late Paleozoic, and its evolution was accompanied by magmatic activity. The latest manifestation of magmatism is eruption of alkaline olivine–leucite basalts on the western side of the Lambert Rift; Rb–Sr dating referred its time to the Middle Eocene, although its genesis remained vague. In order to solve this problem, we found geochronometer minerals in basaltic samples and 68 apatite grains appeared to be suitable for analysis. Their ages and ages of host basalts, determined by the U–Pb local method on the SIMS SHRIMP-II, were significantly different (323 ± 31 Ma) from those assumed earlier. This age corresponds to the earliest stage of crustal extension in East Antarctica and to most of Gondwana. The new data crucially change the ideas about the evolution of Lambert Rift and demonstrate the ambiguity of К–Ar dates of the alkali effusive formed under long-term rifting.

UR - http://www.scopus.com/inward/record.url?scp=85042558605&partnerID=8YFLogxK

U2 - 10.1134/S1028334X18010051

DO - 10.1134/S1028334X18010051

M3 - Article

AN - SCOPUS:85042558605

VL - 478

SP - 11

EP - 14

JO - Doklady Earth Sciences

JF - Doklady Earth Sciences

SN - 1028-334X

IS - 1

ER -