Reply to comment on “Accordion vs. quantum tectonics: Insights into continental growth processes from the Paleozoic of eastern Gondwana”

Aitchison, Jonathan C.; Buckman, Solomon

doi:10.1016/j.gr.2012.12.014

Cited by 2 publications

(1 citation statement)

References 16 publications

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“…This is in contrast to the “accordion tectonics” hypothesis endorsed in this study that supports a nearly continuous continental arc, that is, accretionary orogen undergoing periods of extension during slab retreat and compression during slab advance (Cawood et al, ; Collins, ). For our purposes, we interpret our data within the model of accretionary orogenesis because it has been widely applied to zircon Hf isotope data sets along the paleo‐Pacific margin of Gondwana (e.g., Kemp et al, ; Li et al, ; Pepper et al, ; Phillips et al, ; Rey et al, ), and there remains no consensus on the appropriate tectonic model for the evolution of the margin (Aitchison & Buckman, ; Fergusson, ).…”

Section: Discussionmentioning

confidence: 99%

Long‐Term Geochemical and Geodynamic Segmentation of the Paleo‐Pacific Margin of Gondwana: Insight From the Antarctic and Adjacent Sectors

Nelson

Cottle

2017

Tectonics

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Combined zircon geochemistry and geochronology of Mesozoic volcaniclastic sediments of the central Transantarctic Mountains, Antarctica, yield a comprehensive record of both the timing and geochemical evolution of the magmatic arc along the Antarctic sector of the paleo‐Pacific margin of Gondwana. Zircon age populations at 266–183 Ma, 367–328 Ma, and 550–490 Ma correspond to episodic arc activity from the Ediacaran to the Jurassic. Zircon trace element geochemistry indicates a temporal shift from granitoid‐dominated source(s) during Ediacaran to Early Ordovician times to mafic sources in the Devonian through Early Jurassic. Zircon initial εHf shifts to more radiogenic Hf isotope compositions following the Ross Orogeny and is inferred to reflect juvenile crustal growth within an extensional arc system during progressive slab rollback. These new ages and Hf isotopic record are similar to those from the Australian sector, indicating that these regions constituted an ~3,000 km laterally continuous extensional arc from at least the Carboniferous to the Permian. Conversely, the South American sector records enriched zircon Hf isotopic compositions and compressional/advancing arc tectonics during the same time period. Our new data constrain the location of this profound along‐arc geochemical and geodynamic “switch” to the vicinity of the Thurston Island block of West Antarctica.

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