Cinder cone clustering in the TransMexican Volcanic Belt: Implications for structural and petrologic models

Abstract

Cinder cone distributions have most often been characterized using univariate statistics. Here a new technique to volcano distribution studies, cluster analysis, is applied to cinder cone distribution in the central TransMexican Volcanic Belt (TMVB). A total of 1016 cinder cones are identified over an area of approximately 60,000 km2. Application of cluster analysis reveals structure in cinder cone distribution. Using a search radius parameter of 16 km, 75% of the cinder cones within the central TMVB are found within eight clusters of 45–159 cones each. These clusters are each 2000 to 5000 km2 in area. Only 22 cones are found within clusters of three or fewer cinder cones, indicating that clustering is a pervasive phenomenon. Some petrologic variation is evident among clusters; low‐Mg alkaline cinder cones are found within a single cluster, 360–400 km from the trench. Application of alignment analysis techniques, including the two‐point azimuth method, the Hough transform, and two‐dimensional Fourier analysis demonstrates that cinder cone alignments have common orientations on a regional scale within three clusters, all located in the southernmost part of the Michoacán‐Guanajuato volcanic field in the western portion of the study area. These alignments consist of tens of cinder cones, are 20–50 km long, and are all oriented with azimuths of 020°–040°, parallel to the direction of plate convergence. High‐Mg lavas, which last fractionated at pressures in excess of 8 kbar, are only found associated with these alignments, indicating that magma transport is significantly enhanced in these areas. Although local alignments of three to six cinder cones occur within mapped fault zones that transect the area, regional cinder cone alignment patterns, and the distribution of clusters themselves, do not appear to be affected by the presence of these fault zones. The cluster analysis, the alignment analysis, and some petrologic data support the hypothesis that the TMVB is segmented near 101°W.