TY - JOUR
T1 - U-Th isotopes in arc magmas
T2 - Implications for element transfer from the subducted crust
AU - Hawkesworth, C. J.
AU - Turner, S. P.
AU - McDermott, F.
AU - Peate, D. W.
AU - Van Calsteren, P.
PY - 1997/4/25
Y1 - 1997/4/25
N2 - Uranium-thorium isotope results from island arc volcanic rocks were used to investigate the rates of transfer of fluids and sediments from the downgoing slab. Uranium, but not thorium, is readily mobilized in the fluid. A negative array between thorium/cerium and neodymium-143/neodymium-144 indicates that significant amounts of the thorium in arc rocks are derived from subducted sediments, although perhaps only about 30 percent of the thorium in subducted sediments is returned to the crust in this way. The transfer times for fluid through the mantle wedge are about 30,000 to 120,000 years, whereas those for sediment melts may be several million years. The low average uranium/thorium ratios of bulk crust primarily reflect different crustal generation processes in the Archaean.
AB - Uranium-thorium isotope results from island arc volcanic rocks were used to investigate the rates of transfer of fluids and sediments from the downgoing slab. Uranium, but not thorium, is readily mobilized in the fluid. A negative array between thorium/cerium and neodymium-143/neodymium-144 indicates that significant amounts of the thorium in arc rocks are derived from subducted sediments, although perhaps only about 30 percent of the thorium in subducted sediments is returned to the crust in this way. The transfer times for fluid through the mantle wedge are about 30,000 to 120,000 years, whereas those for sediment melts may be several million years. The low average uranium/thorium ratios of bulk crust primarily reflect different crustal generation processes in the Archaean.
UR - http://www.scopus.com/inward/record.url?scp=0030620728&partnerID=8YFLogxK
U2 - 10.1126/science.276.5312.551
DO - 10.1126/science.276.5312.551
M3 - Article
C2 - 9110968
AN - SCOPUS:0030620728
VL - 276
SP - 551
EP - 555
JO - Science (New York, N.Y.)
JF - Science (New York, N.Y.)
SN - 0036-8075
IS - 5312
ER -