Is the Proterozoic Ladoga Rift (SE Baltic Shield) a rift?

Artemieva, Irina M. and Shulgin, Alexey (2015) Is the Proterozoic Ladoga Rift (SE Baltic Shield) a rift? Precambrian Research, 259 . pp. 34-42. DOI 10.1016/j.precamres.2014.08.011.

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The southern part of the Baltic Shield hosts a series of mafic dykes and sills of Mesoproterozoic ages, including a ca. 1.53–1.46 Ga sheet-like gabbro-dolerite sills and the Salmi plateau-basalts from the Lake Ladoga region. Based on chiefly geochemical data, the region is conventionally interpreted as an intracratonic Ladoga rift (graben). We question the validity of this geodynamic interpretation by analyzing regional geophysical data (crustal structure, heat flow, Bouguer gravity anomalies, magnetic anomalies, and mantle Vs velocities). We provide a complete list of tectonic, magmatic, and geophysical characteristics typical of continental rifts in general and demonstrate that, except for magmatic and, perhaps, some gravity signature, the Lake Ladoga region lacks any other rift features. We also compare the geophysical data from the Lake Ladoga region with similar in age Midcontinent and Valday rifts, and provide alternative explanations for Mesoproterozoic geodynamic evolution of the southern Baltic Shield. We propose that Mesoproterozoic mafic intrusions in southern Fennoscandia may be associated with a complex deformation pattern during reconfiguration of (a part of) Nuna (Columbia) supercontinent, which led to magma intrusions as a series of mafic dykes along lithosphere weakness zones and ponding of small magma pockets within the cratonic lithosphere. Consequent magma cooling and its partial transition to eclogite facies could have led to the formation of a series of basement depressions, similar to intracratonic basins of North America, while spatially heterogeneous thermo-chemical subsidence, with phase transitions locally speeded by the presence of (subduction-related) fluids, could have produced a series of faults bounding graben-like structures.

Document Type: Article
Additional Information: WOS:000350516900003
Keywords: Continental rifting; Rift definitions; Intracratonic basins; Nuna supercontinent; East European craton
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
DOI etc.: 10.1016/j.precamres.2014.08.011
ISSN: 0301-9268
Date Deposited: 09 Dec 2014 12:27
Last Modified: 03 Nov 2016 11:26

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