TY - JOUR

T1 - Clarification of Pasha Rift Structure in Pasha-Ladoga Basin Based on AMT and Gravity Data

AU - Stepanov, K.

AU - Antashchuk, Kseniya

AU - Saraev, Alexander

PY - 2016

Y1 - 2016

N2 - Clarification of the Pasha-Ladoga Basin structure was conducted using a joint interpretation of audiomagnetotelluric (AMT) and gravity data. AMT investigations were performed along a regional profile with a length of 86 km, and three additional 10 km profiles within the south-eastern part of the basin. A four-layered geoelectrical model was obtained up to a depth of 2 km according to 2D inversion results of AMT data, and model interpretation enabled determination of the upper and lower boundaries of Riphean rocks in the Ladoga-Pasha Basin. Maximum thickness of the zone of the Riphean deposits was established in the central part of the regional profile, and two conductive zones were determined in the crystalline basement structure; these are probably related to faults and graphitic zones. Joint AMT and gravity data interpretation results clarified a division of the Pasha-Ladoga Basin area and determined two fore deeps and a central linear zone with a trough structure, where the zone is characterized by a maximum thickness of Riphean deposits and corresponds to the linear positive anomaly of the gravity field in a north-western direction. Results of gravity field modeling show that this anomaly relates to dense rocks, which are probably basalts and mafic volcanic rocks, and which have a lower boundary depth of 4–5 km. The structure of this zone and its filling by mafic volcanic rocks can be interpreted as a rift structure, and based on gravity data the rift structure is found to extend to the Ladoga Lake area, with an observed length of about 140 km and a width of 17–25 km. The results obtained in this study allow better definition of the borders and specification of the Pasha structure’s rift origin.

AB - Clarification of the Pasha-Ladoga Basin structure was conducted using a joint interpretation of audiomagnetotelluric (AMT) and gravity data. AMT investigations were performed along a regional profile with a length of 86 km, and three additional 10 km profiles within the south-eastern part of the basin. A four-layered geoelectrical model was obtained up to a depth of 2 km according to 2D inversion results of AMT data, and model interpretation enabled determination of the upper and lower boundaries of Riphean rocks in the Ladoga-Pasha Basin. Maximum thickness of the zone of the Riphean deposits was established in the central part of the regional profile, and two conductive zones were determined in the crystalline basement structure; these are probably related to faults and graphitic zones. Joint AMT and gravity data interpretation results clarified a division of the Pasha-Ladoga Basin area and determined two fore deeps and a central linear zone with a trough structure, where the zone is characterized by a maximum thickness of Riphean deposits and corresponds to the linear positive anomaly of the gravity field in a north-western direction. Results of gravity field modeling show that this anomaly relates to dense rocks, which are probably basalts and mafic volcanic rocks, and which have a lower boundary depth of 4–5 km. The structure of this zone and its filling by mafic volcanic rocks can be interpreted as a rift structure, and based on gravity data the rift structure is found to extend to the Ladoga Lake area, with an observed length of about 140 km and a width of 17–25 km. The results obtained in this study allow better definition of the borders and specification of the Pasha structure’s rift origin.

KW - Audiomagnetotelluric sounding

KW - Gravity survey

KW - Pasha rift

KW - Pasha-Ladoga Basin

M3 - Article

VL - 51

SP - 51

EP - 67

JO - Geophysica

JF - Geophysica

SN - 0367-4231

IS - 1-2

ER -