Paleoproterozoic high-Mg low-Ti gabbro-granite series in eastern Sarmatia: Geochemistry and formation conditions

Abstract

We present nomenclature and geochemical classification of Paleoproterozoic LILE-enriched high-Mg low-Ti mafic-granitoid rocks of the eastern margin of the Sarmatia paleocontinent and substantiate their tectonic position. Two differentiated rock series are recognized:(1) biotite-orthopyroxene melanorite-quartz-meladiorite-melagranodiorite and (2) hornblende-biotite quartz-diorite-tonalite-granodiorite. Both series correspond in chemical composition to calc-alkalic gabbro-diorites, diorites, tonalites, and granodiorites. As follows from their mineralogical and geochemical compositions, these are norite-diorite rocks (intrusive analogs of boninites) (SiO 2 = 52-65 wt.%, MgO = 5-20 wt.%, TiO 2 = 0.2-0.8 wt.%) and high-Mg granitoids (SiO 2 = 60-70 wt.%, Na 2 O/K 2 O = 0.65-1.33, MgO = 3.23-7.40 wt.%, K 2 O = 1.9-4.0 wt.%), respectively. Their high Mg# values (67-87) and Cr contents (>100 ppm), on the one hand, and their isotope-geochemical characteristics similar to those of the host metaterrigenous rocks, the magma enrichment in LILE, and the presence of Ni sulfide ores with a predominance of light sulfur isotopes, on the other, testify to crustal contamination of mantle magmas. The rock series are nearly of the same age and belong to the same magmatic system, where high-Mg granitoids are differentiates of parental high-Mg (boninite-like) norite-dioritic magma. This is confirmed by a gradual increase in SiO 2 and K 2 O contents and a decrease in Mg# and Ni, Co, V, and Cr contents in the sequence from norites to granodiorites and by the facies and phase relationships between the series. Intrusion of rocks took place at shallow depths following the low-temperature metamorphism and folding under postcollisional collapse of the East Sarmatian orogen.

The Telychian (early Silurian) oxygenation event in northern Europe: A geochemical and magnetic perspective

“…As can be seen the records available are strongly biased to igneous datasets with limited metasediment data from western Sarmatia and southern Svecofennian basement. Terentiev et al (2016aTerentiev et al ( ,b, 2017Terentiev et al ( , 2018Terentiev et al ( ,2020, Terentiev & Santosh (2016), Terentiev & Savko (2016). South Svecofennian Igneous Åhäll et al (2002), Baginski et al (2001), Dorr et al (2002, Mansfeld (1996), Skridlaitė et al (2003Skridlaitė et al ( , 2007, Soesoo et al (2006), Sundblad et al (1994), Wiszniewska et al (2002Wiszniewska et al ( , 2007.…”

Geochemistry and geochronology of quartz monzogabbro – monzodiorite – granodiorites of the Potudan pluton (Volga-Don orogen)

“…Дискриминантная диаграмма Дж. Пирса с фигуративными точками составов пород Хохольско-Репьевского батолита: зеленые квадраты -потуданский тип, красное поле -павловский тип кварцмонцодиорит-лейкогранодиоритного комплекса внедряются 2.07-2.04 млрд лет назад (Terentiev et al, 2016 a), относятся к известково-щелочной серии и близки к I-гранитам. Предполагается участие в образовании плутонических комплексов как мантийных, так и коровых компонентов (Терентьев, 2014;Терентьев и Савко, 2016;Терентьев и Савко, 2017;.…”

Никеленосный Еланский Комплекс Воронежского Кристаллического Массива: Состав И Номенклатура Пород

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