U-Pb-Hf-REE-Ti zircon and REE garnet geochemistry of the Cambrian Attunga eclogite, New England Orogen, Australia: Implications for continental growth along eastern Gondwana

被引:14
作者
Manton, Ryan J. [1 ]
Buckman, Solomon [1 ]
Nutman, Allen P. [1 ]
Bennett, Vickie C. [2 ]
Belousova, Elena A. [3 ]
机构
[1] Univ Wollongong, Sch Earth & Environm Sci, GeoQuEST Res Ctr, Wollongong, NSW, Australia
[2] Australian Natl Univ, Res Sch Earth Sci, Canberra, ACT, Australia
[3] Macquarie Univ, GEMOC, N Ryde, NSW, Australia
关键词
eclogite; New England Orogen; Eastern Gondwana; Weraerai terrane; zircon U-Pb; zircon; garnet REE; NEW-SOUTH-WALES; LACHLAN FOLD BELT; ULTRAHIGH-PRESSURE METAMORPHISM; LU-HF; NEW-CALEDONIA; FORE-ARC; K-AR; ACCRETIONARY OROGENESIS; FRANCISCAN SUBDUCTION; SERPENTINITE MELANGE;
D O I
10.1002/2016TC004408
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
The timing and location of eclogite metamorphism is central to understanding subduction events responsible for the assembly of eastern Gondwana. The Attunga eclogite is one of only six eclogites in Australia and occurs as small blocks within a schistose serpentinite melange known as the Weraerai terrane, along the Peel Fault of the southern New England Orogen. Our zircon data reveal the presence of high Th/U oscillatory zoned magmatic zircon with a weighted mean Pb-206/U-238 age of 53414Ma and recrystallized metamorphic domains with an age of 49014Ma. The latter have lower Th/U ratios, mostly no Eu anomalies and heavy rare earth element (HREE)-depleted patterns. Garnet rims demonstrate that the final stages of garnet growth occurred in a HREE-depleted environment, due to coeval formation with metamorphic zircon. Direct application of the Ti-in-zircon thermometer to metamorphic zircon yields temperatures of 770-610 degrees C. Hf isotopic analyses of the zircons have an average epsilon Hf-(t) of +13, indicating a juvenile crustal signature. We interpret the Attunga eclogite to be an indicator of Late Cambrian subduction beneath an oceanic suprasubduction zone prior to accretion against eastern Gondwanan in the latest Devonian. Phillips et al. () suggest two metamorphic age populations within the Attunga eclogite, based on U-Pb zircon and 40Ar/39Ar phengite data. These are similar to 515Ma and similar to 480Ma. We confirm these data, but our zircon trace element chemistry data indicate that the Early Cambrian age (530Ma) represents igneous protolith formation rather than eclogite metamorphism.
引用
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页码:1580 / 1613
页数:34
相关论文
共 209 条
[1]   Transient, synobduction exhumation of Zagros blueschists inferred from P-T, deformation, time, and kinematic constraints:: Implications for Neotethyan wedge dynamics [J].
Agard, P. ;
Monie, P. ;
Gerber, W. ;
Omrani, J. ;
Molinaro, M. ;
Meyer, B. ;
Labrousse, L. ;
Vrielynck, B. ;
Jolivet, L. ;
Yamato, P. .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 2006, 111 (B11)
[2]   Exhumation of oceanic blueschists and eclogites in subduction zones: Timing and mechanisms [J].
Agard, P. ;
Yamato, P. ;
Jolivet, L. ;
Burov, E. .
EARTH-SCIENCE REVIEWS, 2009, 92 (1-2) :53-79
[3]  
Aitchison J, 1994, Volcanism associated with extension at consuming plate margins, V81, P155, DOI DOI 10.1144/GSL.SP.1994.081.01.09
[4]   EARLY PERMIAN TRANSFORM MARGIN DEVELOPMENT OF THE SOUTHERN NEW-ENGLAND OROGEN, EASTERN AUSTRALIA (EASTERN GONDWANA) [J].
AITCHISON, JC ;
FLOOD, PG .
TECTONICS, 1992, 11 (06) :1385-1391
[5]   PALEOZOIC OPHIOLITIC ASSEMBLAGES WITHIN THE SOUTHERN NEW-ENGLAND OROGEN OF EASTERN AUSTRALIA - IMPLICATIONS FOR GROWTH OF THE GONDWANA MARGIN [J].
AITCHISON, JC ;
BLAKE, MC ;
FLOOD, PG ;
JAYKO, AS .
TECTONICS, 1994, 13 (05) :1135-1149
[6]  
AITCHISON JC, 1992, GEOLOGY, V20, P125, DOI 10.1130/0091-7613(1992)020<0125:MZAFOF>2.3.CO
[7]  
2
[8]   AGE PROFILE OF OPHIOLITIC ROCKS ACROSS THE LATE PALEOZOIC NEW-ENGLAND OROGEN, NEW-SOUTH-WALES - IMPLICATIONS FOR TECTONIC MODELS [J].
AITCHISON, JC ;
IRELAND, TR .
AUSTRALIAN JOURNAL OF EARTH SCIENCES, 1995, 42 (01) :11-23
[9]   Accordion vs. quantum tectonics: Insights into continental growth processes from the Paleozoic of eastern Gondwana [J].
Aitchison, Jonathan C. ;
Buckman, Solomon .
GONDWANA RESEARCH, 2012, 22 (02) :674-680
[10]   THE NATURE AND ORIGIN OF ECLOGITE BLOCKS IN SERPENTINITE FROM THE TAMWORTH BELT, NEW-ENGLAND FOLD BELT, EASTERN AUSTRALIA [J].
ALLAN, AD ;
LEITCH, EC .
AUSTRALIAN JOURNAL OF EARTH SCIENCES, 1992, 39 (01) :29-35