Nikolas I. Christensen Howard G. Wilshire Thomas E. Parsons 1995 <div id="15576312" class="article-section-wrapper js-article-section js-content-section " data-section-parent-id="0"><p>To reconcile differences between the assessments of crustal composition in the southern Basin and Range province on the basis of seismic refraction and reflection data and lower-crustal xenoliths, we measured velocities of xenoliths from the Cima volcanic field in southern California. Lower-crustal samples studied included gabbro, microgabbro, and pyroxenite. We find that the mafic xenolith velocities are compatible with regional in situ measurements from seismic refraction studies, provided that a mixture of gabbro and pyroxenite is present in the lower crust. Supporting this model are observations that many of the lower-crustal xenoliths from the Cima volcanic field are composites of these rock types, with igneous contacts. Vertical incidence synthetic seismograms show that a gabbroic lower crust with occasional pyroxenite layering can produce a reflective lower crust that is similar in texture to that shown by seismic reflection data recorded nearby.</p></div> application/pdf 10.1130/0091-7613(1995)023<0129:VOSBAR>2.3.CO;2 en Geological Society of America Velocities of southern Basin and Range xenoliths: Insights on the nature of lower crustal reflectivity and composition article