updated 9/30/2004 keith updated 4/1/2003 kit Georef Data 2000-073550 TI Timing of volcanism in the Sierra Nevada of California; evidence for Pliocene delamination of the batholithic root?. AU Manley-Curtis-R; Glazner-Allen-F; Farmer-G-Lang AF "University of North Carolina at Chapel Hill, Department of Geological Sciences, Chapel Hill, NC, United States" SO "Geology Boulder. 28; 9, Pages 811-814. 2000." PB "Geological Society of America GSA. Boulder, CO, United States. 2000." CP United-States PY 2000 LA English AB "Recent seismic experiments across the southern Sierra Nevada, California, show that the range lacks a thick crustal root. Xenolith studies indicate that delamination and loss of much of the lower crust may have occurred between 10 and 3 Ma. We estimate that delamination occurred ca. 3.5 Ma on the basis of a sudden pulse of mafic potassic magmatism within and just east of the Sierra Nevada from 4 to 3 Ma. This pulse interrupted the low level of volcanism that had prevailed regionally since 13 Ma. Delamination could have promoted magmatism via decompression melting, heating of the shallow lithosphere by upwelling asthenosphere, and foundering of crustal rocks into the mantle, and could have provided dynamic support to the range. Foundering of the lower crust may have occurred spontaneously, owing to negative buoyancy, or may have been triggered by extension between the Sierra Nevada and Death Valley." DE absolute-age; Ar-Ar; batholiths-; California-; Cenozoic-; continental-crust; crust-; dates-; delamination-; igneous-rocks; inclusions-; intrusions-; magmatism-; Nd-Nd; Neogene-; Pliocene-; potassic-composition; Sierra-Nevada; tectonics-; Tertiary-; United-States; uplifts-; volcanic-rocks; volcanism-; xenoliths- CC 05A-Igneous-and-metamorphic-petrology; 03-Geochronology DT Serial BL Analytic NN With GSA Data Repository Item 200085. IL Refs RF "GeoRef, Copyright 2002, American Geological Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States" IS 0091-7613 CO GLGYBA Table Heading Table 1. New Argon Ages of Sierran Volcanic Rocks Sample Data Item Station_Number Age Max_age Min_age Age Max_age Min_age LatDD rock_type material LongDD Loc_prec Location _Name State Units Ma Ma Ma Ma Ma Ma DD DD Method 1 1 1 2 2 2 3 3 3 Sample Name GG97-6 1 3.58 3.78 3.38 36.7806 volcanic mineral -118.8964 0.0001 South of Hume Lake California 97CA-TD-12 2 4.22 4.42 4.02 36.9578 volcanic whole rock -118.9062 0.0001 Cabin Creek California 97CA-TD-1 3 3.36 3.62 3.1 36.9771 volcanic whole rock -118.8411 0.0001 Near Volcanic Cone California SL97-19 4 9.81 10.53 9.09 37.1192 volcanic whole rock -119.393 0.0001 Sugarloaf California SC6A 5 3.15 3.33 2.97 36.9648 volcanic whole rock -118.8 0.0001 Sceptre Creek California ML97-30 6 9.07 9.44 8.7 37.0241 volcanic whole rock -119.5886 0.0001 Table Mtn California ML97-31 7 9.25 9.55 8.95 37.0233 volcanic whole rock -119.5884 0.0001 Table Mtn California ML97-32 8 10.37 10.83 9.91 37.1744 volcanic whole rock -119.5122 0.0001 Kerkhoff Reservoir California KP97-25B 9 3.84 4.18 3.5 37.3991 volcanic whole rock -119.2317 0.0001 Brown Cone California MP97-19 10 3.43 3.62 3.24 37.5937 volcanic whole rock -119.2665 0.0001 Cora Lakes California BK111 11 7.76 8.22 7.3 37.5481 volcanic whole rock -119.3167 0.0001 Blue Knob California Method Data 1 Ar-Ar:PHLOG 346 2 Ar-Ar:WR 346 3 TABLE 2000-073550