Petrographic Analysis of Rocks and Sediments Around the Seven Lakes of San Pablo Laguna: Implications to Sulfate Distribution and Provenance

Rene Juna R. Claveria, Teresita R. Perez, Jona Kristel V. Tesorero, Benica Joy D. Pasaporte and Gillian Mari S. Bayugo

Department of Environmental Science
Aterneo de Manila University

Abstract

The 7 lakes of San Pablo are among the 20 small monogenetic volcanoes found at the Macolod Corridor of the Southwestern Luzon Volcanic Field. This study has evaluated the relationship of sulfate distribution and provenance in sediments to the volcanic geology and origin of the lakes. Rock and sediment mineralogy indicated the absence of sulfur-sulfate bearing minerals. This is supported by the very low sulfate values in rocks from previous analyses. The elevated sulfate values previously noted in sediments however are not related to volcanism but are attributed to anthropogenic sources. Considered possible sources of sulfate are sewage, fertilizers, algicides and fungicides.