Geochronology and provenance of the Late Paleozoic accretionary wedge and Gympie Terrane, New England Orogen, eastern Australia

被引:54
作者
Korsch, R. J. [1 ]
Adams, C. J. [2 ]
Black, L. P. [1 ]
Foster, D. A. [3 ]
Fraser, G. L. [1 ]
Murray, C. G. [4 ]
Foudoulis, C. [1 ]
Griffin, W. L. [5 ]
机构
[1] Geosci Australia, Onshore Energy & Minerals Div, Canberra, ACT 2601, Australia
[2] GNS Sci, Lower Hutt, New Zealand
[3] Univ Florida, Dept Geol Sci, Gainesville, FL 32611 USA
[4] Geol Survey Queensland, Indooroopilly, Qld 4068, Australia
[5] Macquarie Univ, ARC Natl Key Ctr Geochem Evolut & Metallogeny Con, Dept Earth & Planetary Sci, N Ryde, NSW 2109, Australia
关键词
accretionary wedge; argon-argon dating; Carboniferous; geochronology; New England Orogen; provenance; turbidites; uranium-lead dating; U-PB ZIRCON; FORE-ARC-BASIN; FOLD BELT; DETRITAL-ZIRCON; SUBDUCTION COMPLEX; TAMWORTH BELT; CONODONT BIOSTRATIGRAPHY; 40AR/39AR GEOCHRONOLOGY; TECTONIC IMPLICATIONS; ISOTOPIC CONSTRAINTS;
D O I
10.1080/08120090902825776
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
In easternmost Australia, the New England Orogen contains a geological record dominated by subduction-related rocks, with plate convergence during the Late Devonian to Triassic being related to a west-dipping subduction system, assuming present-day orientation, at the boundary of eastern Gondwanaland and the Panthalassan Ocean. A well-preserved Late Paleozoic accretionary wedge contains deep-marine turbidites deposited as trench fill, plus infaulted slices of oceanic crust. The turbidites are mostly first-cycle, immature, quartz-poor, volcanic-derived sedimentary rocks, some of which contain detrital hornblende, along with less-common quartz-rich sandstones to the east. In this study, detrital zircons from sandstones in various tectonic blocks of the New England Orogen are dated by the U-Pb SHRIMP and LA-ICPMS techniques and detrital hornblendes by the Ar-Ar technique to constrain the age and provenance of sedimentary rocks in the accretionary wedge. All samples, except two quartz-rich sandstones from the northern Shoalwater Formation, have maximum depositional ages of 355-316 Ma, indicating that the accretionary wedge evolved over a period of at least 40 Ma, with principal sources from a contemporaneous active continental margin volcanic arc. Quartz-rich sandstones from the easternmost part of the accretionary wedge (Shoalwater Formation and eastern Beenleigh Block) contain a greater range of individual detrital zircon ages from Late Paleozoic to Archean (several individual grains3000 Ma). These ages indicate that, although detritus from Carboniferous volcanic arc sources was involved, quartz-rich detritus mostly derived from the continental interior dominated the depocentres. We suggest that these quartz-rich sandstones accumulated from longitudinal transport along the trench, like the modern-day Barbados Ridge accretionary wedge, along with breaching of the marginal arc by streams draining the continental interior.
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页码:655 / 685
页数:31
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