IMPORTANCE OF LINKED FIELD, CORE, AND PETROGRAPHIC STUDIES IN MARINE VOLCANICLASTIC SUCCESSIONS IN SPACE AND TIME: BUILDING ON FIELD STUDIES SPEARHEADED BY CATHY BUSBY IN BAJA CALIFORNIA

Petrographic studies integrated with field or core observations can provide important data for interpretation of marine volcaniclastic successions. In ancient lithified successions, post-depositional diagenesis/metamorphism often modifies or removes vitric and crystal components but variably preserves particle textures. Interpretation of these units must rely on comparison of textural evidence with that of unaltered Cenozoic analogues. We discuss linkages made between Mesozoic outcrop studies of marine magmatic-arc facies spearheaded by Cathy Busby on Baja California and Cenozoic core studies from DSDP, ODP, and IODP exploration of intraoceanic magmatic-arc systems in the western Pacific. We then expand to potential applications and new discoveries in Guaymas Basin, Mexico, where volcaniclastic intervals cored on IODP Expedition 385 and DSDP Leg 64 have epiclastic to pyroclastic origins based on particle textures. Petrographic analyses demonstrate that morphological attributes of Guaymas volcanic particles reveal fundamental information about the types of eruptions occurring in and surrounding Guaymas Basin, along with the mechanisms driving the transport and deposition of volcanic debris, including epiclastic detritus from Isla Tortuga. These interpretations are also used to establish preliminary intrabasinal correlations that will aid in the construction of a more robust chronostratigraphic framework for the basin and provide insight into the interactions between magmatism and sedimentation in the central Gulf of California. These studies broaden models of textural modes based on petrography of magmatic-arc products to products of mafic magmatism associated with oceanic spreading ridges and intraplate volcanic islands.