New Perspectives on the Bishop Tuff from Zircon Textures, Ages and Trace Elements

被引:107
作者
Chamberlain, K. J. [1 ]
Wilson, C. J. N. [1 ]
Wooden, J. L. [2 ]
Charlier, B. L. A. [3 ]
Ireland, T. R. [4 ]
机构
[1] Victoria Univ Wellington, Sch Geog Environm & Earth Sci, Wellington 6140, New Zealand
[2] Stanford Univ, Dept Geol & Environm Sci, Stanford, CA 94305 USA
[3] Open Univ, Dept Phys Sci, CEPSAR, Milton Keynes MK7 6AA, Bucks, England
[4] Australian Natl Univ, Res Sch Earth Sci, Canberra, ACT 0200, Australia
关键词
zircon; U-Pb dating; Bishop Tuff; supervolcano; sector zoning; trace elements; MAGMATISM PHASE-EQUILIBRIA; TI-IN-ZIRCON; U-PB AGE; CANYON SANIDINE STANDARD; K-40 DECAY CONSTANTS; LONG-VALLEY; RHYOLITIC MAGMA; RESIDENCE TIMES; MELT INCLUSIONS; JOINT DETERMINATION;
D O I
10.1093/petrology/egt072
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
We present zircon textural, trace element and U-Pb age data obtained by secondary ion mass spectrometry (SIMS) (SHRIMP-RG: sensitive high-resolution ion microprobe, reverse geometry) from 15 stratigraphically controlled Bishop Tuff samples and two Glass Mountain (GM) lava samples (domes OD and YA). Bishop zircon textures divide into four suites: (a) dominant sector-zoned grains, with (b) subordinate grains showing bright rims [lower U, Th, rare earth elements (REE)] in CL imaging, (c) sparse GM-type grains (texturally similar to zircons from GM dome YA) and (d) sparse Mesozoic xenocrysts from Sierran granitoid country rocks. All Bishop zircons from suites (a)-(c) combined have a weighted mean age of 777 center dot 9 +/- 2 center dot 2 ka (95% confidence) and a tail back to similar to 845 ka. Our eruption age estimate using the weighted mean of 166 rim ages of 766 center dot 6 +/- 3 center dot 1 ka (95% confidence) is identical within uncertainty to published estimates from isotope-dilution thermal ionization mass spectrometry (ID-TIMS) (767 center dot 1 +/- 0 center dot 9 ka, 2 Sigma) and 40Ar/39Ar (767 center dot 4 +/- 2 center dot 2 ka, 2 Sigma) techniques, the latter using the 28 center dot 172 Ma age for the Fish Canyon sanidine standard. We estimate also an eruption age for GM dome YA of 862 +/- 23 ka (95% confidence), significantly older than the currently accepted 790 +/- 20 ka K-Ar age. The oldest zircon cores from late-erupted Bishop material (including those with GM-type textures) have a weighted mean age of 838 center dot 5 +/- 8 center dot 8 ka (95% confidence), implying that the Bishop Tuff system was active for only similar to 80 kyr, and had effectively no temporal overlap with the GM system. Trace element variations in Bishop zircons are influenced strongly for many elements by sector zoning, producing up to 3x concentration differences between sides and tips within the same growth zone. Contrasting trends in molar (Sc + Y + REE3+)/P ratios between sides and tips indicate contrasting mechanisms of substitution in different sectors of the same crystal. Concentrations of Ti in tips are double those in the sides of crystals, hindering applicability of the Ti-in-zircon thermometer, in addition to variations inherent to the 0 center dot 15-0 center dot 67 range in values proposed for aTiO(2). The bright-rim portions of grains are inferred to have crystallized from the same magma as that which generated the bright rims seen under cathodoluminescence or back-scattered electron imaging on quartz and feldspar, respectively. This less evolved, slightly hotter magma invaded the deeper parts of the chamber represented in the late-erupted northern units possibly up to similar to 10 kyr prior to eruption, but invaded shallower levels only very shortly before eruption, as shown by our textural information and previously proposed from the sharp delineation of quartz bright rims. By obtaining a large number of analyses from zircon separates that systematically cover the entire Bishop Tuff eruption sequence we can produce an eruption age estimate using SIMS to the same precision and accuracy as ID-TIMS and 40Ar/39Ar techniques.
引用
收藏
页码:395 / 426
页数:32
相关论文
共 109 条
[1]   From mush to eruption in centuries: assembly of the super-sized Oruanui magma body [J].
Allan, Aidan S. R. ;
Morgan, Daniel J. ;
Wilson, Colin J. N. ;
Millet, Marc-Alban .
CONTRIBUTIONS TO MINERALOGY AND PETROLOGY, 2013, 166 (01) :143-164
[2]   Evolution of Bishop Tuff rhyolitic magma based on melt and magnetite inclusions and zoned phenocrysts [J].
Anderson, AT ;
Davis, AM ;
Lu, FQ .
JOURNAL OF PETROLOGY, 2000, 41 (03) :449-473
[3]   On the origin of crystal-poor rhyolites: Extracted from batholithic crystal mushes [J].
Bachmann, O ;
Bergantz, GW .
JOURNAL OF PETROLOGY, 2004, 45 (08) :1565-1582
[4]   VOLCANISM, STRUCTURE, AND GEOCHRONOLOGY OF LONG-VALLEY CALDERA, MONO-COUNTY, CALIFORNIA [J].
BAILEY, RA ;
DALRYMPLE, GB ;
LANPHERE, MA .
JOURNAL OF GEOPHYSICAL RESEARCH, 1976, 81 (05) :725-744
[5]   Petrogenetic connections between ash-flow tuffs and a granodioritic to granitic intrusive suite in the Sierra Nevada arc, California [J].
Barth, A. P. ;
Feilen, A. D. G. ;
Yager, S. L. ;
Douglas, S. R. ;
Wooden, J. L. ;
Riggs, N. R. ;
Walker, J. D. .
GEOSPHERE, 2012, 8 (02) :250-264
[6]   Birth of the Sierra Nevada magmatic arc: Early Mesozoic plutonism and volcanism in the east-central Sierra Nevada of California [J].
Barth, A. P. ;
Walker, J. D. ;
Wooden, J. L. ;
Riggs, N. R. ;
Schweickert, R. A. .
GEOSPHERE, 2011, 7 (04) :877-897
[7]   Coupled elemental and isotopic analyses of polygenetic zircons from granitic rocks by ion microprobe, with implications for melt evolution and the sources of granitic magmas [J].
Barth, Andrew P. ;
Wooden, Joseph L. .
CHEMICAL GEOLOGY, 2010, 277 (1-2) :149-159
[8]   Igneous zircon: trace element composition as an indicator of source rock type [J].
Belousova, EA ;
Griffin, WL ;
O'Reilly, SY ;
Fisher, NI .
CONTRIBUTIONS TO MINERALOGY AND PETROLOGY, 2002, 143 (05) :602-622
[9]   Post-caldera volcanism: in situ measurement of U-Pb age and oxygen isotope ratio in Pleistocene zircons from Yellowstone caldera [J].
Bindeman, IN ;
Valley, JW ;
Wooden, JL ;
Persing, HM .
EARTH AND PLANETARY SCIENCE LETTERS, 2001, 189 (3-4) :197-206
[10]   Oxygen isotope study of the Long Valley magma system, California: isotope thermometry and convection in large silicic magma bodies [J].
Bindeman, IN ;
Valley, JW .
CONTRIBUTIONS TO MINERALOGY AND PETROLOGY, 2002, 144 (02) :185-205