Early cretaceous tectonic setting of eastern Australia: Evidence from the subduction-related Morton Igneous Association of Southeast Queensland

Henderson, Robert, Spandler, C., Foley, E.K., Kemp, A.I.S., Roberts, E.M., and Fisher, C. (2022) Early cretaceous tectonic setting of eastern Australia: Evidence from the subduction-related Morton Igneous Association of Southeast Queensland. Lithos, 410. 106573.

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Abstract

Early Cretaceous magmatic rocks of the central east coast of Australia are recognized as a lithologically, geochemically, and geochronologically distinctive rock package herein named the Morton Igneous Association. The association embraces small plutons and hypabyssal intrusions within the Jurassic and Lower Cretaceous Nambour and Maryborough basins. It also includes volcanics of the Grahams Creek Formation, basal infill of the Marybomugh Basin with an indicated volume exceeding 0.25 M km(3), representing a much more substantial igneous assemblage. Plutonic rocks vary from hornblende-rich gabbro to granodiorite, and syenite. The Grahams Creek Formation consists of volcanic to volcaniclastic rocks of basaltic to dacitic composition. The association is U-Pb zircon dated at 145-140 Ma, and is characterized by distinctive subduction-related trace element compositions typical of magmatic rocks from continental arc settings. Oxygen isotope and EHf compositions obtained from zircon are consistent with a largely mantle source for the host magmas. Trace element data for the 130-95 Ma Whitsunday Igneous Province, of more northerly location on the east Australian coast, are consistent with a continental back-arc association. The MIA and Whitsunday Igneous Province represent small parts of an extensive Cretaceous active margin system developed for east Gondwana, mainly located on continental crust comprising northern Zealandia which is now separated from east Australia, largely submerged and little documented. East Australia records both older (145-140 Ma) continental arc magmatism and younger (132-95 Ma) continental back-arc magmatism attributed to progressive Cretaceous roll-back of a consuming plate boundary to east Gondwana.

Item ID: 73283
Item Type: Article (Research - C1)
ISSN: 0024-4937
Keywords: Eastern Australia, Magmatic arc, Early Cretaceous, Geochemistry, Zircon U-Pb, Lu-Hf, O isotopes
Copyright Information: © 2021 Elsevier B.V. All rights reserved.
Funders: Australian Research Council (ARC)
Projects and Grants: ARC Discovery Project Jurassic Arc DP180102851
Date Deposited: 30 Mar 2022 08:00
FoR Codes: 37 EARTH SCIENCES > 3705 Geology > 370503 Igneous and metamorphic petrology @ 25%
37 EARTH SCIENCES > 3703 Geochemistry > 370303 Isotope geochemistry @ 50%
37 EARTH SCIENCES > 3705 Geology > 370511 Structural geology and tectonics @ 25%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280107 Expanding knowledge in the earth sciences @ 80%
25 MINERAL RESOURCES (EXCL. ENERGY RESOURCES) > 2599 Other mineral resources (excl. energy resources) > 259999 Other mineral resources (excl. energy resources) not elsewhere classified @ 20%
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