San Quintín Volcanic Field
Mexico · Americas
About
The San Quintín Volcanic Field is a collection of ten or eleven volcanic cinder cones situated along the Pacific coast of the Baja California peninsula in Mexico. The field formed by repeated eruptions beginning in the Pleistocene and ending about 3000 years ago. It is one of several known Quaternary period volcanic fields in Baja. The lava shields appear to have first grown as subaqueous volcanoes that emerged as islands. Currently located in a shallow bay, the cones are found in two groups and two isolated islands. The Northern group is composed of two cones, formed 126,000–90,000 years ago; the Southern group is larger, with two cones in the lagoon itself, and formed over a much larger and undetermined span of time. Most volcanic complexes in the field have a well-preserved scoria cone and lava apron, dotted with eruptive vents and lava flows. 42 eruptive units can be seen on the ground today. The San Quintín field is the only known location of intraplate-type mafic alkalic volcanism on the Baja California peninsula. The oldest cones mainly erupted primitive magmas with occasional small xenoliths. As the field evolved, differentiated magma became more common, although extremely pure primitive magmas – virtually devoid of xenoliths and unusually rich in olivine phenocrysts – still dominated at the young cones. These primitive magmas originated from progressive partial melting
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