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Skały w krajobrazie obszaru Barberton (RPA) i ich potencjał geoturystyczny

Radwanek-Bąk Barbara, Bąk Bogusław

Przegląd Geologiczny

2023

Vol. 71, nr 1

44--50

The area around the city of Barberton in the north-east part of South Africa is built of varied rocks belonging to the so-called Barberton Greenstone Belt (BGB), which are among the oldest (Paleo-and Mesoarchaic) and best preserved in the world. Their observation directly in the field is possible thanks to the “Barberton Makhonjwa Geotrail” created in 2014. The article briefly presents the geological structure of this area and provides important information on the development of the Earth in the Archaic, in the light of the latest research. Examples of representative outrops of BGB rocks and the close relationship between the geological structure and morphology are presented. The important raw materials of this area, including rich gold deposits (“Sheba”and others), known since the 19th century, are also mentioned.

Wstępne wyniki badań petrograficznych archaicznych gnejsów Uivak (Prowincja Nain, Labrador)

Sałacińska A., Kusiak M. A.

Przegląd Geologiczny

2017

Vol. 65, nr 6

383--391

The Saglek Block of the Nain Complex in Northern Labrador forms the westernmost part of the North Atlantic Craton. It is one of the few regions on Earth where early Archaean crust is preserved. It consists of regionally metamorphosed gneisses to either granulite-facies from 2.74 to 2.71 Ga or amphibolite-facies at ca. 2.70 Ga. The Saglek Block is dominated by two suites of metaigneous gneisses: the Uivak I TTG suite (>3.6 Ga) and the Uivak II augen gneisses (ca. 3.4 Ga). Four samples offelsic Uivak I orthogneiss were selected to petrographi- cal and mineralogical studies: Johannes Point Cove (L1419), TigigakyukInlet (L1434; L1440) and Big Island (L1443). Sample composition (granodiorite-tonalite) and mineralogy (mostly plagioclase and quartz, with minor K-feldspar and biotite, and accessory zircon and apatite) for three of the four samples are consistent with published data of the Uivak I gneiss. Sample L1434 contains ferroean diopside and hornblende, which are absent in the other samples. Based on detailed mineralogical analyses, authors concluded that more mafic sample, can not belong to the suite of the Uivak I gneisses. Most probably it represents the younger Uivak II. Further, geochronological study is going to be conducted to characterise both, Uivak I and Uivak II gneisses isotopically.