{"id":230,"date":"2012-02-12T19:48:11","date_gmt":"2012-02-12T19:48:11","guid":{"rendered":"http:\/\/www.geol.umd.edu\/facilities\/seismology\/?p=230"},"modified":"2013-02-13T19:49:53","modified_gmt":"2013-02-13T19:49:53","slug":"lithospheric-thinning-beneath-rifted-regions-of-southern-california","status":"publish","type":"post","link":"https:\/\/www.geol.umd.edu\/facilities\/seismology\/lithospheric-thinning-beneath-rifted-regions-of-southern-california\/","title":{"rendered":"Lithospheric thinning beneath rifted regions of Southern California"},"content":{"rendered":"

Conversions of teleseismic shear (S) waves to compressional (P) waves across velocity interfaces (such as the Moho or the lithosphere-asthenosphere boundary) allow us to map out variations in plate thickness across Southern California. Anomalously thin lithosphere is observed beneath rifted regions, such as the Salton Trough.<\/p><\/blockquote>\n

The stretching and break-up of lithosphere through a process called rifting controls the evolution\u00a0of continents and formation of oceans. Constraints on the kinematics and dynamics of rifting are\u00a0almost exclusively provided by surface geologic and geochemical observations combined with\u00a0geophysical imaging of the crust. What happens to the underlying mantle lithosphere during\u00a0rifting is poorly known, in large part because seismologists have yet to image lithospheric\u00a0variations across an active rift system. Here, we detect mode conversions of teleseismic shear\u00a0waves across the lithosphere-asthenosphere boundary (LAB) beneath Southern California, and present the first maps of lithospheric thickness that resolve variations on lengthscales relevant for\u00a0constraining continental rifting. LAB depth varies from ~90 to ~40 km below the region, with thick lithosphere present beneath the Peninsular and Transverse Ranges, and thin lithosphere\u00a0beneath the Salton Trough and the Continental Borderland. In the Salton Trough, lithospheric\u00a0thinning is substantially greater than crustal thinning; the two can be reconciled if substantial\u00a0mafic underplating \/ intrusion and\/or rapid metamorphosis of sediment into basement rock are\u00a0occurring. Our results demonstrate that lithospheric thinning occurs over very similar lengthscale\u00a0as and is not systematically offset with respect to surficial and crustal expressions of rifting,\u00a0consistent with a mode of deformation that is either pure-shear or simple-shear along steeply\u00a0dipping shear zones. Furthermore, rapid horizontal variations in \u00a0lithospheric thinning suggest\u00a0efficient strain localization within the lithosphere.<\/p>\n

 <\/p>\n

You can read more about this work in a recently published Report in\u00a0Science<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

Conversions of teleseismic shear (S) waves to compressional (P) waves across velocity interfaces (such as the Moho or the lithosphere-asthenosphere boundary) allow us to map out variations in plate thickness across Southern California. Anomalously thin lithosphere is observed beneath rifted regions, such as the Salton Trough. The stretching and break-up of lithosphere through a process […]<\/p>\n","protected":false},"author":1,"featured_media":231,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[5],"tags":[],"class_list":["post-230","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-research"],"_links":{"self":[{"href":"https:\/\/www.geol.umd.edu\/facilities\/seismology\/wp-json\/wp\/v2\/posts\/230","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.geol.umd.edu\/facilities\/seismology\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.geol.umd.edu\/facilities\/seismology\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.geol.umd.edu\/facilities\/seismology\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.geol.umd.edu\/facilities\/seismology\/wp-json\/wp\/v2\/comments?post=230"}],"version-history":[{"count":1,"href":"https:\/\/www.geol.umd.edu\/facilities\/seismology\/wp-json\/wp\/v2\/posts\/230\/revisions"}],"predecessor-version":[{"id":232,"href":"https:\/\/www.geol.umd.edu\/facilities\/seismology\/wp-json\/wp\/v2\/posts\/230\/revisions\/232"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.geol.umd.edu\/facilities\/seismology\/wp-json\/wp\/v2\/media\/231"}],"wp:attachment":[{"href":"https:\/\/www.geol.umd.edu\/facilities\/seismology\/wp-json\/wp\/v2\/media?parent=230"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.geol.umd.edu\/facilities\/seismology\/wp-json\/wp\/v2\/categories?post=230"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.geol.umd.edu\/facilities\/seismology\/wp-json\/wp\/v2\/tags?post=230"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}