Multiple P–T–d–t paths reveal the evolution of the final Nuna assembly in northeast Australia

Abstract

This is the author manuscript accepted for publication and has undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as

Structural Evolution of a 1.6 Ga Orogeny Related to the Final Assembly of the Supercontinent Nuna: Coupling of Episodic and Progressive Deformation

“…Tectonics with the development of a steep (60-80°), ESE dipping pervasive axial planar cleavage S1 (Figures 5b-5g) defined by biotite shape preferred orientation (SPO) and minor fine-grained quartz-opaque aggregates ( Figure 4). It is axial planar (S1) to the observed F1 folds, confirming that it is the first tectonic fabric recorded in this area, that is characterized by a greenschist facies mineral assemblage (i.e., M1 in Volante et al, 2020). Mineral lineation and S0/S1 intersection lineations (L1) plunge southeast, parallel to the F1 fold hinges (Figure 5f).…”

“…Locally, S1 is statically overgrown by randomly oriented centimeter-scale andalusite porphyroblasts, which are generally localized in the most micaceous layers. Hence, andalusite is postkinematic to S1, but it is not accompanied by the development of a new fabric (i.e., M2a in Volante et al, 2020) Figure 5f) in the northern area (e.g., Western Creek). The S3 cleavage becomes progressively more pervasive and penetrative southward (e.g., Townley Station).…”

“…This S2 fabric truncates the D1 structures at a high angle in the northern part of the study area ( Figure 3), but farther south D1 and D2 structures tend to be realigned into D3 orientations, where F3 folds are more intensely developed. Volante et al, 2020). Proterozoic rocks overlay a greyscale mosaic of total field magnetic intensity (TMI) data where the first vertical derivatives (1VD) was applied.…”

“…Evolution of the 1.60-1.50 Ga Orogenic Event in the GTI 5.1.1. First Deformation Event (D1) D1 structures (e.g., S1a and S1b) in the western and central domains were identified microstructurally and dated using Lu-Hf in garnet and U-Pb in monazite geochronology at circa 1600 Ma (Volante et al, 2020). Regional mapping of the Western Creek area has identified the original orientation of the F1 folds and the associated S1 fabric, to be NNE trending ( Figure 5).…”

“…The second deformation event is extensively recorded in the central and eastern domains but not in the western domain where static overgrowth of andalusite over S1 at circa 1550 Ma (M2a in Volante et al, 2020) also indicate that D2 did not affect the domain. This dichotomy might reflect the presence of a tectonic contact between the western and the central domains, which is pervasively overprinted by the D2/M2 event (see discussion below).…”