Metamorphic Processes in East Antarctic Crustal Development

The East Antarctic Shield preserves a complex metamorphic record spanning Neoproterozoic to Paleozoic orogenies. High-grade metamorphism was driven by successive tectonothermal events associated with supercontinent assembly and breakup, notably the Grenvillian continental collisions and the Pan-African orogeny. Granulite-facies rocks in the Larsemann Hills record peak conditions of ca 870 °C and 9–10 kbar, indicative of crustal thickening and subsequent exhumation during arc-continent and continent-continent collisions. Subsequent Pan-African reworking introduced polymetamorphic signatures, resetting isotopic systems in monazite, rutile and hornblende while preserving older high-temperature fabrics. Geophysical imaging of subglacial domains has revealed suture-related discontinuities in Moho geometry and low-resistivity channels, marking collisional belts such as the Prydz and Kuunga orogens. Integrating petrological P–T paths with zircon U–Pb and Lu–Hf data has refined the timing of metamorphic pulses and crustal growth processes, elucidating the assembly of Gondwana. Ongoing work emphasises heterogeneity in basement affinity, with Australian and Indian crustal fragments traced offshore and onshore via detrital zircons. These insights not only chart the thermal–tectonic evolution of the East Antarctic craton but also inform resource potential and global reconstructions of ancient supercontinents.

Research from Nature Portfolio

Recent studies have employed offshore detrital zircon geochronology to delineate two distinct basement provinces in coastal East Antarctica, of Indian versus Australian affinity. Combining U–Pb ages with geophysical lineaments, researchers have located the buried Kuunga orogen and marked the Indo-Australo-Antarctic suture beneath ice. These findings provide a refined map of crustal block boundaries and reconstruct Ediacaran–Cambrian displacements of 3000–5000 km during Gondwana formation, thereby illuminating the tectonic underpinnings of high-grade metamorphic domains in the interior shield.

Metamorphic Processes in East Antarctic Crustal Development publication trend

The graph below shows the total number of articles in metamorphic processes in east antarctic crustal development across all publications each year (not limited to Nature Index journals).

Technical terms

Suture zone: A deep crustal boundary marking the collision interface between terranes or continental blocks.

Moho discontinuity: The boundary separating Earth’s crust from the underlying mantle, identified by seismic velocity contrasts.

Granulite facies metamorphism: High-temperature, moderate-pressure metamorphism producing minerals such as garnet, sillimanite and orthopyroxene.

U–Pb geochronology: Radiometric dating method using uranium-lead decay in zircon to determine crystallisation and metamorphic ages.

P–T path: The pressure–temperature trajectory experienced by a rock during metamorphism, revealing burial and exhumation history.

References

1. Geophysical Evidence of the Collisional Suture Zone in the Prydz Bay, East Antarctica. Geophysical Research Letters (2024).
2. A cryptic Gondwana-forming orogen located in Antarctica. Scientific Reports (2018).
3. Grenville-age metamorphism in the Larsemann Hills: P-T evolution of the felsic orthogneiss in the Broknes Peninsula, East Antarctica. International Geology Review (2020).
4. The impact of the Pan-African-aged tectonothermal event on high-grade rocks at Mount Brown, East Antarctica. Antarctic Science (2020).