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

The study of diverse mantle-derived igneous complexes is important for interpreting geodynamic events, ore deposits formation mechanisms, and ore-forming fluid sources. Modern studies of orogenic gold deposits in the Precambrian metamorphosed terranes emphasize the importance of subduction-enriched lithospheric mantle in the ore formation processes. Orogenic gold mineralization in the Nimnyr terrane of the Aldan-Stanovoy shield is confined to the outcrops of mafic granulites from the Medvedev complex, intruded and metamorphosed 1.92–1.90 Ga ago at the final stage of the collision process. The Medvedev complex and ore bodies are intersected by non-metamorphosed dolerites of the 1.87 Ga Timpton-Gynym and 1.75 Ga Timpton-Algamai dike belts formed under conditions of post-collisional and intracontinental extension. The mantle-derived igneous complexes, presenting in a variety of geodynamic settings and ore mineral formation stages, make it possible to identify compositional and evolutionary features of the mantle in connection with ore formation processes. To do this, there were determined rock-forming oxide and trace element concentrations in pre-ore mafic granulites of the Medvedev complex and post-ore dolerites. Based on the geochemical data, there was a reconstruction of rock and mantle source type formation conditions. It was found that the rocks of the Medvedev complex are plume-derived. Doleritic melt formation was contributed to by the subduction-enriched lithospheric mantle material. There is a possility of different degrees of source melting and interaction of plume with the enriched lithospheric mantle at the final stage of the collision process. The obtained results can be used to refine the geodynamic models of gold mineralization formation in the central part of the Aldan-Stanovoy shield. There has been proposed one of the standard models.

Section: Figunclassified

Geodynamics and Ore Content of Proterozoic Maphites in the Central Part of the Aldan-Stanovoy Shield (Southern North Asian Craton)

Kravchenko,

Okrugin,

Beryozkin

et al. 2024

“…Вы полненные с тех пор UPb и Sm/Nd изотопные определения, отвечающие современным требованиям к качеству геохронологических данных, не подтверждают, однако, гипотезу о широком развитии в пределах Ана барского поднятия многочисленных эпизодов позднедокембрийского базитового магматизма. Имеющиеся на настоящий момент современные данные говорят о том, что практически все геохронологически изучен ные позднедокембрийские базитовые тела Анабарско го региона сформировались в относительно небольшом промежутке времени ~1480-1500 млн лет назад и только единичные дайки имеют возраст ~1380 и ~1770 млн лет [Ernst et al, 2000;Gladkochub et al, 2022].…”

Section: Introductionunclassified

“…Геологическая картасхема Анабарского массива и известные прецизионные определения возраста докембрийских интрузивных тел (а); холодный контакт силла (PR 2 ) с карбонатами эдиакарской старореченской свиты (V st ) (б) и горячий контакт силла (PR 2 ) с карбонатами раннерифейской юсмастахской свиты билляхской серии (R1 bl ) (в). 1 -отложения палеозоя; 2 -отложения венда; 3 -отложения рифея; 4 -образования архейпротерозойского фундамента; 5 -интрузивные образования основного состава; 6 -известные достоверные определения возраста: а - [Ernst et al, 2016], б - [Tomshin et al, 2023], в - [Gladkochub et al, 2022], г - [Veselovskiy et al, 2006]; 7 -точки отбора образцов этого исследования: а -пермскотриасовых даек, б -рифейских силлов, в -геохронологической пробы. Tomshin et al, 2023;Wingate et al, 2009;Malyshev et al, 2022].…”

Section: Introductionunclassified

Two Pulses of Magmatic Activity During the Early Riphean Kuonamka Igneous Province Formation: Paleomagnetic Substantiation of the Hypothesis

Pasenko,

Fedyukin,

Pavlov

2024

By the beginning of the 20th century, at least ten different generations of intrusive mafic bodies 1800–900 Ma were distinguished on the territory of the Anabar massif. The first modern age estimates, however, indicate the formation of the bulk of these bodies in a relatively short period of time ~1480–1500 Ma. Based on geochronological and paleomagnetic data, intrusive bodies with this age were combined into the Kuonamka large igneous province (LIP). However, a complex of paleomagnetic studies indicated the probable existence of at least two pulses of magmatic activity during the formation of this province, differing in age, possibly by ~20 Ma. We performed a paleomagnetic study of subvolcanic bodies of the main composition of Permo-Triassic (dykes) and Mesoproterozoic (sills) age, emerging to the surface in the valley of the middle reaches of the Kotui River. As expected, the studied dikes contain an ancient magnetization, the direction of which is typical for Permo-Triassic magmatic bodies of the region and the Siberian platform as a whole, and the paleomagnetic directions of the sills are close to those previously determined in the age-related subvolcanic bodies of the Kuonamka igneous province (1501±3 Ma) of the Anabar massif. The data obtained allow us to test the previously proposed hypothesis about the existence of two magmatic pulses ~1480 and 1500 Ma ago during the formation of the Kuonamka igneous province. The results of the analysis of already known and new paleomagnetic data obtained by us do not support this hypothesis. A refined paleomagnetic pole was proposed for the Siberian platform ~1500 Ma ago with coordinates 22.6° S, 65.0° E and A95=4.3°.

“…-cеверо-северо-западные дайки Восточно-Анабарского роя Тимптонской КМП с возрастом 1774-1750 млн лет [Gladkochub et al, 2010[Gladkochub et al, , 2019[Gladkochub et al, , 2022Ernst et al, 2016a].…”

Section: Introductionunclassified

KENGEDE MAFIC DYKE SWARM AND EXPANSION OF THE 1.50 Ga KUONAMKA LARGE IGNEOUS PROVINCE OF NORTHERN SIBERIA

Tomshin,

Ernst,

Söderlund

et al. 2023

Self Cite

Within the Anabar shield in the northern part of the Siberia, Late Precambrian mafic igneous units are widespread, which form dyke swarms of different ages of different trends. This paper presents new data on the composition, structure and U-Pb dating of the E-W trending Kengede dyke swarm. Three new U-Pb ID-TIMS baddeleyite ages (1496±7, 1494±3 and 1494±5 Ma) were obtained from three dykes, indicating that the Kengede swarm is part of the 1500 Ma Kuonamka large igneous province (LIP). The previously recognized Kuonamka Large Igneous Province (LIP) extends for 700 km from the Anabar shield to the Olenek uplift in the northern part of the Siberia and is potentially linked to coeval dykes and sills of the São Francisco craton and the Congo craton. The newly dated Kengede swarm is parallel to but offset by 50 km from the previously dated 1501±3 Ma Kuonamka swarm, and the identification of these two subparallel dyke subswarms of the Kuonamka LIP supports the earlier interpretation that mantle plume centre was located along the extrapolated trend of the dykes near the eastern or western margin of the Siberia. The paper examines features of sulfide Cu-Ni mineralization in dolerites of the Kengede and East Anabar dyke swarms and discusses potential Cu-Ni-sulfide mineralization linked to the Precambrian mafic dyke swarms of different ages in the north-east of the Siberia.