TY - JOUR

T1 - Meso-Neoproterozoic Mafic Sills along the South-Eastern Margin of the Siberian Craton, SE Yakutia: Petrogenesis, Tectonic and Geochemical Features

AU - Savelev, Aleksandr D.

AU - Malyshev, Sergey V.

AU - Savatenkov, Valery M.

AU - Ignatov, Daniil D.

AU - Kuzkina, Anastasia D.

N1 - Funding Information: Funding: Nd isotopes analysis of samples AS18-21 and AS18-22 has been carried out within the mega-grant in accordance with Resolution of the RF Government (Agreement No. 14.Y26.31.0012). Other studies were funded by the Russian Science Foundation, grant number 19-77-10048.

PY - 2020/9/12

Y1 - 2020/9/12

N2 - We report major and trace element concentrations, along with Nd isotope compositions, for Late Mesoproterozoic to Early Neoproterozoic dolerite sills from the Sette-Daban ridge (southern Verkhoyansk, south-east Siberia). Based on their major element composition, all rocks correspond to low-Ti (<3 wt% TiO 2) moderately alkaline basalts. The intrusions can be subdivided into two groups based on their trace element compositions. One group includes sills mainly distributed in the southern part of the study area (Yudoma group), with mid-ocean ridge basalt (MORB) trace element patterns enriched in aqueous fluid mobile incompatible (FMI) elements (Sr, Pb, Ba, U). The second group includes sills mostly distributed in the northern part of the study area, enriched in immobile incompatible (II) elements (Th, Nb, light rare earth elements (LREE)) and to a lesser extent, in aqueous fluid mobile elements. The Nd isotope signatures of the dolerites characterize a depleted mantle source, with a small enrichment from recycled continental crust. The geochemical characteristics of these igneous rocks are analogous to low-Ti basalts of large intraplate provinces (e.g., the Karoo and Siberian Traps). We propose that they formed by rifting-induced melting of the heterogeneous metasomatized shallow spinel-bearing mantle zone. We suggest that two different melting sources were involved in the generation of the two geochemically distinct sill groups, including the addition of two different subduction components. The southern sills were formed by melting of depleted lithospheric mantle enriched with FMI elements, corresponding to subduction-induced metasomatic alteration by fluids at shallow depths. The northern dolerites were formed by melting of depleted lithospheric mantle enriched with II elements, associated with the melting of subducted sediments at deeper depths.

AB - We report major and trace element concentrations, along with Nd isotope compositions, for Late Mesoproterozoic to Early Neoproterozoic dolerite sills from the Sette-Daban ridge (southern Verkhoyansk, south-east Siberia). Based on their major element composition, all rocks correspond to low-Ti (<3 wt% TiO 2) moderately alkaline basalts. The intrusions can be subdivided into two groups based on their trace element compositions. One group includes sills mainly distributed in the southern part of the study area (Yudoma group), with mid-ocean ridge basalt (MORB) trace element patterns enriched in aqueous fluid mobile incompatible (FMI) elements (Sr, Pb, Ba, U). The second group includes sills mostly distributed in the northern part of the study area, enriched in immobile incompatible (II) elements (Th, Nb, light rare earth elements (LREE)) and to a lesser extent, in aqueous fluid mobile elements. The Nd isotope signatures of the dolerites characterize a depleted mantle source, with a small enrichment from recycled continental crust. The geochemical characteristics of these igneous rocks are analogous to low-Ti basalts of large intraplate provinces (e.g., the Karoo and Siberian Traps). We propose that they formed by rifting-induced melting of the heterogeneous metasomatized shallow spinel-bearing mantle zone. We suggest that two different melting sources were involved in the generation of the two geochemically distinct sill groups, including the addition of two different subduction components. The southern sills were formed by melting of depleted lithospheric mantle enriched with FMI elements, corresponding to subduction-induced metasomatic alteration by fluids at shallow depths. The northern dolerites were formed by melting of depleted lithospheric mantle enriched with II elements, associated with the melting of subducted sediments at deeper depths.

KW - Geochemistry

KW - Mafic rock

KW - Metasomatized mantle

KW - Sette-Daban

KW - Sills

KW - South-East Siberia

UR - http://www.scopus.com/inward/record.url?scp=85090759646&partnerID=8YFLogxK

U2 - 10.3390/min10090805

DO - 10.3390/min10090805

M3 - Article

VL - 10

SP - 1

EP - 20

JO - Minerals

JF - Minerals

SN - 2075-163X

IS - 9

M1 - 805

ER -