We present new geochemical and Nd isotopic data on two Mesoproterozoic Listvyanka (1350 ± 6 Ma) and Goloustnaya (1338 ± 3 Ma) mafic dyke swarms located in the Irkutsk Promontory of the southern part of the Siberian craton. Listvyanka dykes are sub-vertical with NNE trend, while Goloustnaya dykes are characterized by prevailing W trend. Listvyanka and Goloustnaya dykes are composed of medium to coarse grained dolerites. All dolerites correspond to sub-alkaline tholeiitic basalts according to their major-element compositions with lower to moderate mg#, varying from 36 to 54. The trace and rare earth element abundances in Listvyanka and Goloustnaya dolerites are generally close to basalts of the oceanic island basalts (OIB) type. The Listvyanka dolerites demonstrate slightly positive eNd(t) values varying from +1.1 to +1.5, while the Goloustnaya dolerites are characterized by lower eNd(t) values ranging from −0.9 to +0.1. Geochemical and isotopic affinities of the Listvyanka dolerites suggest their enrichment by a mantle plume related source. For the Goloustnaya dolerites, we assume also some additional lithospheric input to their mantle plume-related source. The emplacement of both studied dolerites took place in intracontinental extensional setting, caused by a single rising mantle plume. Listvyanka and Goloustnaya dolerites are coeval to several mafic magmatic events in northern Laurentia and likely represent part of the Mesoproterozoic plumbing system of a Siberian–Laurentian Large Igneous Province.

https://www.mdpi.com/2075-163X/8/12/545/pdf

Geochemistry and petrogenesis of mesoproterozoic dykes of the irkutsk promontory, southern part of the Siberian Craton

1.79–1.75 Ga mafic magmatism of the Siberian craton and late Paleoproterozoic paleogeography

Numerous orogenic gold deposits of different age, scale, and mineralization type are located within Northern Transbaikalia. Among them, there is a large group of Early Permian deposits, whose sources and relationships with Late Paleozoic magmatism remain debatable. These issues were solved by the example of the middle-scale (~24 t, Au) Irokinda deposit, localized within the Precambrian rocks of the Baikal–Muya Terrane. 39Ar–40Ar geochronological dating of the ore-hosting altered rocks indicates that hydrothermal–metasomatic process took place about 270 myr ago. Gold mineralization has heterogeneous Pb-, S-, Sr-, and Nd-isotopic characteristics. Variations in the Pb, S, Sr, and Nd isotopic composition of ore and gangue minerals suggest that the mineral-forming components were involved in the hydrothermal system from different sources. Among them, the leading role belonged to the rocks of the Precambrian crust of the Baikal–Muya Terrane. Pb isotopic composition of the second identified source is close to that of the Early Permian alkaline and subalkaline rocks of the Baikal–Muya Terrane. This fact may indicate a genetic relationship between the Irokinda gold mineralization and intraplate alkaline magmatism, which developed in the region simultaneously with ore-forming processes.

Sources and Age of the Gold Mineralization of the Irokinda Deposit, Northern Transbaikalia: Evidence from Pb, S, Sr, and Nd Isotope-Geochemical and 39 Ar– 40 Ar Geochronological Data

The article discusses the history of the development of analytical research at the Institute of the Earth’s Crust, Siberian Branch of the Russian Academy of Sciences over the past 22 years. An overview of the existing scientific equipment, current analytical techniques and some examples of their application in geological research are provided. It is shown that the availability of highly qualified personnel and modern scientific equipment at the Center for Geodynamics and Geochronology allows, both entirely on its base and in cooperation with other Russian and foreign organizations, to conduct state of the art research with the publication of results in leading international journals.

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History and current state of analytical research at the Institute of the Earth’s Crust SB RAS: Centre for geodynamics and geochronology

Lead Isotope Systematics of the Orogenic Gold Deposits of the Baikal-Muya Belt (Northern Transbaikalia): Contribution of the Subcontinental Lithospheric Mantle in Their Genesis

A.V. Chugaev

Papers

Geologic structure of the Mukodek gold field (northern Transbaikalia) and sources of matter (Pb–Pb and Sm–Nd data)