| 6909 |
Creator |
169f034520be3a0d0aff86e4441f6f0e |
| 6909 |
Creator |
ext-af161252609a57d6779380106a9b787a |
| 6909 |
Creator |
ext-3ea608ae869e7798c6808c52479e04a1 |
| 6909 |
Creator |
ext-2822ea83e396f4d5ab595eb61b560b00 |
| 6909 |
Creator |
ext-9ed70ac7d91dae54beb9741ad014d22b |
| 6909 |
Creator |
ext-ace017b0458cc3fa7d090cd7eb32026c |
| 6909 |
Date |
2001 |
| 6909 |
Is Part Of |
p00223530 |
| 6909 |
Is Part Of |
repository |
| 6909 |
abstract |
New thermal ionization mass spectrometry U-series disequilibrium data are presented
for 24 basaltic to dacitic glasses from active spreading centres in the back-arc Lau
Basin (SW Pacific), together with additional inductively coupled plasma mass spectrometry
trace element analyses and Sr–Nd–Pb isotope data. Valu Fa Ridge samples, adjacent
to the arc front, have high U/Th and (230Th/238U) <1, implying a recent (<<350 ka)
addition of a U-rich slab-derived fluid. The Valu Fa data can be combined with existing
230Th–238U data for the Central Tonga arc to infer a fluid addition event at 50 ka.
The similar sources and time scales for fluid transfer beneath the Valu Fa Ridge and
beneath the arc itself suggest that the Valu Fa Ridge is propagating into the arc-front
region. Central Lau Basin samples, further behind the arc, have lower U/Th and (230Th/238U)
1, similar to typical mid-ocean ridge basalts (MORB). Within the Central Lau Basin,
a water-rich subduction component is seen only in samples closest to the arc, and
this fluid does not have the high-U/Th composition of the fluid at Valu Fa. Melt generation
in the Central Lau Basin appears to be dominated by normal ridge-type processes, but
the relatively low (230Th/238U) for these shallow ridges compared with global MORB
could be a consequence of increased melt productivity as a result of the elevated
water contents. The transition from 238U to 230Th excesses within the back-arc basin
is not a smooth function of decreasing addition of a U-rich fluid moving away from
the arc front, but also reflects the complex dynamics between two major mantle domains
within the mantle wedge (‘Pacific’ beneath Valu Fa Ridge, ‘Indian’ beneath the Central
Lau Basin). |
| 6909 |
authorList |
authors |
| 6909 |
issue |
8 |
| 6909 |
status |
peerReviewed |
| 6909 |
volume |
42 |
| 6909 |
type |
AcademicArticle |
| 6909 |
type |
Article |
| 6909 |
label |
Peate, David W.; Kokfelt, Thomas F.; Hawkesworth, Chris J.; van Calsteren, Peter
W. ; Hergt, Janet M. and Pearce, Julian A. (2001). U-series Isotope Data on Lau Basin
Glasses: the Role of Subduction-related Fluids during Melt Generation in Back-arc
Basins. Journal of Petrology, 42(8) pp. 1449–1470. |
| 6909 |
label |
Peate, David W.; Kokfelt, Thomas F.; Hawkesworth, Chris J.; van Calsteren, Peter W.
; Hergt, Janet M. and Pearce, Julian A. (2001). U-series Isotope Data on Lau Basin
Glasses: the Role of Subduction-related Fluids during Melt Generation in Back-arc
Basins. Journal of Petrology, 42(8) pp. 1449–1470. |
| 6909 |
Title |
U-series Isotope Data on Lau Basin Glasses: the Role of Subduction-related Fluids
during Melt Generation in Back-arc Basins |
| 6909 |
in dataset |
oro |