Hong-Xiang Hu Rong-Sheng Zeng Walter D. Mooney T. McEvilly Rong-Ju Kan 1986 <div class="panel-pane pane-highwire-panel-tabs-container article__body"><div class="pane-content"><div id="panels-ajax-tab-container-highwire_article_tabs" class="panels-ajax-tab-container" data-panels-ajax-tab-preloaded="jnl_sci_tab_art"><div class="panels-ajax-tab-wrap-jnl_sci_tab_art"><div class="panel-display panel-1col clearfix"><div class="panel-panel panel-col"><div><div class="panel-pane pane-highwire-markup"><div class="pane-content"><div class="highwire-markup"><div id="content-block-markup" data-highwire-cite-ref-tooltip-instance="highwire_reflinks_tooltip" data-highwire-glossary-tooltip-instance="highwire_reflinks_tooltip"><div class="article abstract-view "><div id="abstract-1" class="section abstract"><p id="p-1">Seismic refraction, profiles in Yunnan Province, southwestern China, define the crustal structure in an area of active tectonics on the southern end of the Himalaya-Burma arc. The crustal thickness ranges from 38 to 46 kilometers, and the relatively low mean crustal velocity indicates a crustal composition compatible with normal continental crust and consisting mainly of meta-sedimentary and silicic intrusive rocks, with little mafic or ultramafic component. This composition suggests a crustal evolution involving sedimentary processes on the flank of the Yangtze platform rather than the accretion of oceanic island arcs, as has been proposed. An anomalously low upper-mantle velocity observed on one profile but not on another at right angles to it may indicate active tectonic processes in the mantle or seismic anisotropy.</p></div></div><span id="related-urls"></span></div></div></div></div></div></div></div></div></div></div></div> application/pdf 10.1126/science.234.4775.433 en Science Crustal structure of Yunnan Province, People's Republic of China, from seismic refraction profiles article