Spatial Patterns in Distribution of Kimberlites: Relationship to Tectonic Processes and Lithosphere Structure

TY - ABST

T1 - Spatial Patterns in Distribution of Kimberlites: Relationship to Tectonic Processes and Lithosphere Structure

AU - Chemia, Zurab

AU - Artemieva, Irina

AU - Thybo, Hans

PY - 2014/12/1

Y1 - 2014/12/1

N2 - Since the discovery of diamonds in kimberlite-type rocks more than a century ago, a number of theories regarding the processes involved in kimberlite emplacement have been put forward to explain the unique properties of kimberlite magmatism. Geological data suggests that pre-existing lithosphere weakness zones may control the spatial patterns of kimberlites, but this hypothesis has never been tested by geophysical methods. As the first step in our analysis of tectonic and lithosphere control of kimberlite-type magmatism, we perform a detailed global analysis of the spatial patterns of kimberlites, and present the first results. The analysis is based on the assumption that the kimberlite emplacement is a two-stage process, and the two stages are controlled by the crustal and lithospheric mantle rheologies, respectively. Stage 1 includes the first-order, lithosphere-scale process that initiate the rise of kimberlite melts through the lithospheric mantle, which forms the major pipe. Stage 2 (second-order process) begins when the major pipe splits into daughter sub-pipes (tree-like pattern) at crustal depths. We apply cluster analysis to the spatial distribution of all known kimberlite fields with the goal of establishing characteristic scales for the stage 1 and stage 2 processes. The results indicate that characteristic scales for the stage 2 are almost globally uniform and thus are almost independent of the structure and the mantle lithosphere. In contrast, the characteristic scales for stage 1 vary over very broad limits and are, apparently controlled, by the past structure of the lithosphere and a "vigor" of lithosphere-mantle interaction, which caused kimberlite emplacements.

AB - Since the discovery of diamonds in kimberlite-type rocks more than a century ago, a number of theories regarding the processes involved in kimberlite emplacement have been put forward to explain the unique properties of kimberlite magmatism. Geological data suggests that pre-existing lithosphere weakness zones may control the spatial patterns of kimberlites, but this hypothesis has never been tested by geophysical methods. As the first step in our analysis of tectonic and lithosphere control of kimberlite-type magmatism, we perform a detailed global analysis of the spatial patterns of kimberlites, and present the first results. The analysis is based on the assumption that the kimberlite emplacement is a two-stage process, and the two stages are controlled by the crustal and lithospheric mantle rheologies, respectively. Stage 1 includes the first-order, lithosphere-scale process that initiate the rise of kimberlite melts through the lithospheric mantle, which forms the major pipe. Stage 2 (second-order process) begins when the major pipe splits into daughter sub-pipes (tree-like pattern) at crustal depths. We apply cluster analysis to the spatial distribution of all known kimberlite fields with the goal of establishing characteristic scales for the stage 1 and stage 2 processes. The results indicate that characteristic scales for the stage 2 are almost globally uniform and thus are almost independent of the structure and the mantle lithosphere. In contrast, the characteristic scales for stage 1 vary over very broad limits and are, apparently controlled, by the past structure of the lithosphere and a "vigor" of lithosphere-mantle interaction, which caused kimberlite emplacements.

KW - 8434 Magma migration and fragmentation

KW - VOLCANOLOGY

KW - 8439 Physics and chemistry of magma bodies

KW - 8450 Planetary volcanism

KW - 8486 Field relationships

M3 - Conference abstract in proceedings

BT - AGU Abstract Database

T2 - American Geophysical Union Fall Meeting 2014

Y2 - 15 December 2014 through 19 December 2014

ER -