Gondwana dispersion and Asian accretion: Tectonic and palaeogeographic evolution of eastern Tethys

Antarctica — Before and after Gondwana

Precambrian crustal evolution of Peninsular India: A 3.0 billion year odyssey

Assembling Australia: Proterozoic building of a continent

Carbonate clumped isotope bond reordering and geospeedometry

[1] The Ross-Delamerian orogenic belt formed along the early Paleozoic active Pacific margin of the newly merged Gondwana supercontinent. In its northernmost segment in the Townsville region of northeastern Australia, we have identified a short contractional phase of the Delamerian orogeny in the Argentine Metamorphics postdating formation of a mafic breccia with a U-Pb zircon age of 500 ± 4 Ma. Contraction was followed by widespread inferred extensional deformation with formation of flat-lying foliation, domal features, and amphibolite grade and greenschist retrograde metamorphism all synchronous with latest Cambrian to Early Ordovician extensional back-arc volcanism, sedimentation, and intrusions. One of these intrusions gives a U-Pb zircon age of 480 ± 4 Ma. Foliation related to the extensional deformation is crosscut by a late granodiorite dike with a U-Pb zircon age of 461 ± 4 Ma. Late east-west contractional deformation affected the higher-grade part of the assemblage. In contrast to the Ross-Delamerian orogenic belt in the Transantarctic Mountains and southeastern Australia, the orogenic belt in northeastern Australia was affected by a short episode of contraction at ∼495 Ma followed by long-lived back-arc extension from ∼490 Ma to 460 Ma with subsequent contractional deformation.

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Structural, metamorphic, and geochronological constraints on alternating compression and extension in the Early Paleozoic Gondwanan Pacific margin, northeastern Australia

The Early Palaeozoic Cape River Metamorphics consist mainly of psammitic gneiss and schist and occur as an extensive linear belt at the western margin of the Charters Towers Province 200 km southwest of Townsville in the northern Tasmanides A prominent foliation (S2) is the main structure in the belt and is associated with tight to isoclinal folds, subparallel mineral and intersection lineations, and boudinaged pods of vein quartz and pegmatite In the southwest, the main foliation is a crenulation cleavage (S2) related to D2 deformation It overprints steeply dipping foliation (S1) formed in a D1 deformation but no associated folds have been found Gently plunging, upright, open folds (D3 deformation) with axial planar S3 crenulation cleavage have affected the main foliation (S2) These deformations were associated with upper greenschist to lower amphibolite facies metamorphism Amphibolite-grade orthogneiss containing S2 and S3, deformed granite and migmatite of the Fat Hen Creek Complex occurs in the 

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Structure of the Early Palaeozoic Cape River Metamorphics, Tasmanides of north Queensland: evaluation of the roles of convergent and extensional tectonics

K. J. Lewthwaite

Papers

Structural, metamorphic, and geochronological constraints on alternating compression and extension in the Early Paleozoic Gondwanan Pacific margin, northeastern Australia

Structure of the Early Palaeozoic Cape River Metamorphics, Tasmanides of north Queensland: evaluation of the roles of convergent and extensional tectonics