Moho discontinuity relief and the distribution of kimberlites and carbonatites in the northern Siberian Platform
Kravchenko, S.; Schachotko, L. I.; Rass, I. T.
published: Jul 31, 1996
ArtNo. ESP136000602009, Price: 19.00 €
The paper presents the results of a comparative analysis of Moho discontinuity ridges, the distribution of kimberlites and carbonatites and supposed mantle convection cell boundaries. Current thinking is that the rift zones have a minimum of crustal thickness and the shallowest Moho level. Chernishov & Bokaya have constructed a map for Moho relief beneath the northern Siberian Platform using deep seismic data and the correlation with crustal thickness and other geophysical characteristics. The constructed map shows that relief of the Moho defines a ridge system with the Moho elevated in some regions more than 14 km above the deepest parts of the Moho. The ridges are 50-80 to 150 km wide and form closed cells, which are 500-800 km across. These Moho ridges are interpreted to mark paleorift zones that have low crustal thickness, contain the thickest platform cover sequences in the western portion of the northern Siberian Platform and, sometimes, also contain neotectonic depressions. The Moho ridges are aligned with deep faults and ring structures 40-60 to 60-80 km across. Some include fields of kimberlite pipes. New data about alkaline ultramafic complexes on the northern Siberian Platform were recently obtained by Kravchenko et al., Rass, Schachotko and Komarov & Ilupin. The ages of the alkaline ultramafic rocks in this region range from Late Proterozoic to Mesozoic. More than 75 % of the kimberlites and carbonatites are localized in the Moho ridges. This suggests that the Moho ridge structures had developed by the Late Proterozoic.