Morphological Study of Jaraguay and San Borja Volcanic Fields, Baja California, Mexico.
Abstract
Volcanism younger than 12.5 Ma has occurred mainly as monogenetic volcanic fields along the Baja California Peninsula, but until now very little attention has been given to the morphological description of this type of volcanism. In this study we present the preliminary results of the first stage of elaboration of a Geographical Information System (GIS) of the northernmost volcanic fields of the Peninsula; Jaraguay and San Borja, which are among the less studied fields in the region. The present status of the GIS includes the main morphological characteristics and localization of over 350 eruptive centers identified in both volcanic fields. Our data show that over 90% of the eruptive centers are cinder cones, whereas the rest of volcanic structures include some stratovolcanos, shield volcanoes and calderas. Detailed analysis of digital elevation models and 14 m resolution Landsat TM images show a remarkable diversity of the size of reported eruptive centers: the average height lies around 720 m with peaks that reaches 1,412 m asl. Preliminary graphic analyses show local concentrations of the biggest volcanic structures in some areas in both fields. This spatial distribution is more evident at the San Borja volcanic field where the biggest volcanic centers are systematically located in its south and north-western boundaries. A similar concentration of bigger volcanic structures is found at the western edge of Jaraguay volcanic field where cinder cones are largely confined to its eastern most edge. The observed morphological changes of volcanic structures occur in both cases within a distance of less than 100 km. We interpret such variations as the result of heterogeneities of the low velocity zone below this particular area of the Baja California Peninsula, although the final evaluation of the distribution of the regional stress field and its relationship with the actual spatial distribution of eruptive centers must wait until more information becomes available. In any case, the results obtained so far can be used to guide future surveys aiming to elucidate the tectonic association of post-subduction volcanism in the Baja California Peninsula.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2005
- Bibcode:
- 2005AGUFM.V21D0641N
- Keywords:
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- 8413 Subduction zone processes (1031;
- 3060;
- 3613;
- 8170);
- 8485 Remote sensing of volcanoes;
- 8499 General or miscellaneous