O.V. Mytrokhyn. PETROLOGY, MINERALOGY AND ORE POTENTIAL OF THE BARCHANS-FORGE GRANITOIDS (ARGENTINE ISLANDS, WEST ANTARCTICA)

https://doi.org/10.15407/mineraljournal.42.02.032

UDC 551.22+552.3+549

PETROLOGY, MINERALOGY AND ORE POTENTIAL OF THE BARCHANS-FORGE GRANITOIDS (ARGENTINE ISLANDS, WEST ANTARCTICA)

O.V. Mytrokhyn, DrSc (Geology), Prof. Kyiv Taras Shevchenko National University

Educational-scientific institute "Institute of Geology"

90, Vasylkivska Str., Kyiv, Ukraine, 03022

E-mail: mitrokhin.a.v@ukr.net

https://orcid.org/0000-0001-6269-0092

V.G. Bakhmutov, DrSc (Geology), Prof., Head of Department.

S.I. Subbotin Institute of Geophysics of the NAS of Ukraine

32, Acad. Palladin Ave., Kyiv, Ukraine, 03142

E-mail: bakhmutovvg@gmail.com

National Antarctic Scientific Center of Ukraine

16, Taras Schevchenko Boul., Kyiv, Ukraine, 01016

E-mail: bakhmutovvg@gmail.com

https://orcid.org/0000-0003-3804-9953

O.L. Marushchenko, MSc student. Kyiv Taras Shevchenko National University

Educational-scientific institute "Institute of Geology"

90, Vasylkivska Str., Kyiv, Ukraine, 03022

E-mail: lesymarush@gmail.com

https://orcid.org/0000-0002-7423-3849

O.V. Andreyev, PhD (Geology), Senior Researcher.

Kyiv Taras Shevchenko National University

Educational-scientific institute "Institute of Geology"

90, Vasylkivska Str., Kyiv, Ukraine, 03022

E-mail: andreev@univ.kiev.ua

https://orcid.org/0000-0003-0954-7777

O.A. Khlon, Lead Engineer. Kyiv Taras Shevchenko National University

Educational-scientific institute "Institute of Geology"

90, Vasylkivska Str., Kyiv, Ukraine, 03022

E-mail: khlon@univ.kiev.ua

https://orcid.org/0000-0001-6750-0489

Language: Ukrainian

Mineralogical journal 2020, 42 (2): 32-45

Abstract:

Paleogen granitoids of Barchans and Forge Islands are the last phase of granitoid magmatism in the Ukrainian Antarctic Station region. The new data concerning the geology and petrographic diversity of the Barchans-Forge granitoids massif (BFGM) were obtained by seasonal investigations in 22nd and 24th Ukrainian Antarctic Expeditions. Optical and electron microscopical investigations, electron microprobe and XRF analyses were carried out. The objectives were the investigation of the geological position of the Barchans-Forge granitoids, the clarification of their petrographical and mineralogical features, and the evaluation of their ore potential. The data testify that only the lateral, marginal part of the large granitoid massif crops out on the Barchans and Forge Islands. Their major part probably locates below sea level north and west from Argentine Islands. The authors argue that the BFGM was formed in the Paleocene as the abyssal level intrusion. Previously published results of K-Ar, Rb-Sr and Ar-Ar isotope dating give an age range 55-60 Ma. The enclosing strata for BFGM are metamorphized volcanic rocks in contact with granitoids on the north-east flank of the massif. Other country rocks are possibly diorites and gabbroids that occur as the xenoliths in the granitoids. The major part of the BFGM consists of granodiorites, as estimated from the petrographical characterization. They are petrographically similar to granodiorites exposed on the Peterman Island located approximately 8 km to the north-east. The Neogene age of exhumation for BFGM was assumed by analogy to the Peterman Island granodiorites, for which previous researchers estimated the exhumation age near 11 Ma. Based on mineralogical and petrographical features, the Barchans-Forge granodiorites are labeled as I-type granitoids. The basic and intermediate igneous rocks are supposedly their magmatic sources. For evaluation of the ore potential of the BFGM the authors recommend to pay attention to their primary magmatic allanite-thorite mineralization as well as to the hydrothermal molybdenite-chalcopyrite mineralization.

Keywords: petrology, mineralogy, granitoids, West Antarctica.

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