Long-lived transcontinental sediment transport pathways of East Gondwana

Sara Morón,Stephen J Gallagher,Peter W Haines,Christopher J Lewis,Sabin Zahirovic,Louis Moresi,Peter A Cawood

doi:10.1130/g45915.1

Abstract

Few modern sediment dispersal pathways predate the breakup of Pangea. This suggests that river lifespan can be controlled by continental assembly and dispersal cycles, with the longest-lived river systems present during supercontinent regimes. Based on the strikingly similar age spectra and Hf isotopic array extracted from Paleozoic to early Mesozoic sedimentary sequences from the Paleo-Tethyan margin basins, we argue that a long-lived supercontinental- scale system, with headwaters originating in Antarctica, flowed northward to finally debouch on the margin with the Paleo-Tethys Ocean. Channel-belt thickness scaling relationships, which provide an estimate of drainage area, support the notion that this was a supercontinental-scale system. Sediments were eroded from Proterozoic orogenic belts and flanked resistant kernels of Archean cratons. Remnants of this system, which can still be traced today as topographic lows, controlled post-breakup drainage patterns in Gondwanan fragments in Western Australia. We conclude that supercontinental regimes allow sediment dispersal systems to be long-lived, as they provide both an abundant sediment supply, due to erosion of large-scale, collision-related internal mountain systems, and a stable, large-scale configuration that lasts until breakup.

Highlights

Sediment dispersal pathways are ubiquitous systems that transverse continental domains, and as such, their evolution and longevity are likely associated with the Wilson cycle (Potter and Hambling, 2006; Gibling, 2017)
To explore the scale and lifespan of sediment transport pathways during supercontinental regimes and the controls involved, we investigate the sediment dispersal patterns of Ordovician–Triassic sequences that were deposited on the Paleo-Tethyan Gondwanan margin
Detrital zircon age spectra and Lu-Hf isotopes from these sequences document a long-lived transcontinental sediment dispersal system with its headwaters in Antarctica, draining through central Australia to final debouch off northwestern Australia

Summary

INTRODUCTION

Sediment dispersal pathways are ubiquitous systems that transverse continental domains, and as such, their evolution and longevity are likely associated with the Wilson cycle (Potter and Hambling, 2006; Gibling, 2017). The origin of large-scale drainage systems such as the Niger (West Africa), Orange (southern Africa), and Paraná (eastern South America) date back to the breakup of Pangea (Reijers et al, 1997; Dingle and Hendry, 1984). This observation poses the questions: what happens to sediment transport pathways during superconti nental regimes, and what, if any, is the relationship between pre- and post-breakup sediment dispersal patterns?. Dated detrital zircons from drill-core samples of Triassic rocks from the Northern Carnarvon Basin, Western Australia (Fig. 1), were analyzed for Lu-Hf isotopes by inductively coupled plasma–mass spectrometry (ICP-MS) (see the GSA Data Repository).

Panthalassa New Guinea

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