Evincing the presence of a trans‐Gondwanian mobile belt in the interior of the Princess Elizabeth Land, East Antarctica: insights from offshore detrital sediments, rock fragments, and monazite geochronology

Abstract

East Gondwana was assembled through the stitching of the Indo‐Antarctica and Australo‐Antarctica domains which also represents the key Gondwana‐forming regions in present‐day East Antarctica. However, the Indo‐Antarctica and Australo‐Antarctica boundaries remain speculative and contentious, as the thick Antarctic Ice sheet precludes direct geological characterization of these terranes. In addition, the exact role of the Gamburtsev Subglacial Mountains, present in the interior of Princess Elizabeth Land (PEL), during the amalgamation of Gondwana, has not been well understood. We present new mineralogical data of offshore sediments from Prydz Bay to infer the geology of the interior of the PEL terrain, East Antarctica. Coast marginal outcrops dominantly expose igneous and granulite facies metamorphic rocks. Heavy minerals characterization of the rock fragments followed by consideration of the outcrop geology indicate a possible contribution of sediments from the far interior of PEL terrain. Total U–Pb chemical geochronology of detrital monazites dominantly shows a bimodal age distribution ascribable to Stenian to Tonian (~1,100 Ma, 900 Ma) event ages and a younger Pan‐African event (~500 Ma). Besides these, Tonian‐Cryogenian (~700 Ma) ages from texturally constrained monazites of a low‐grade schist rock fragment is reported for the first time from this sector. Consideration of glacial flow directions and the nature of rock fragments indicate their sourcing from the distal hinterland. The possible provenance is inferred to be from the Gamburtsev Subglacial Mountains.

Unravelling the complex sub-ice geology of the Wilkes Subglacial Basin region of East Antarctica from marine sediment provenance analyses

“…This is further supported by the newly emerged evidence of Tonian-Cryogenian (c. 700-800 Ma) metamorphic/magmatic events from Neoproterozoic shields worldwide (e.g. Africa: Itano et al 2016, Sommer et al 2017China: Ge et al 2016, Haozheng et al 2020East Antarctica: Jacobs et al 2015, Arora et al 2020, Sadiq et al 2021Gupta et al 2022, and concordant zircon ages of Mikhalsky et al 2020, Zong et al 2020India: Bose et al 2016, Arora et al 2017southern Kazakhstan: Tretyakov et al 2019). Although these ages are reported from almost every Gondwanan component, the events corresponding to c. 700-800 Ma (Tonian-Cryogenian) essentially remain enigmatic in the global orogenic context.…”

“…Marine sedimentary records recovered from the Antarctic continental margin provide the most accessible proxy information on the palaeoclimatic and tectono-thermal evolution of East Antarctica, as these sediments represent source rock domains (Pant et al 2013, Gupta et al 2022). Heavy mineral fractions of the marine sediments reflect provenance characteristics, and the utility of heavy minerals in provenance and process interpretation is widely recognized (e.g.…”

Alpine topography of the Gamburtsev Subglacial Mountains, Antarctica, mapped from ice sheet surface morphology

“…Given that the GSMs are very unlikely to have been deglaciated since this time (Jamieson et al, 2010), it is reasonable to assume that the mapped fluvial network also predates 33.7 Ma (Rose et al, 2013;Paxman et al, 2016), having subsequently been preserved beneath continually cold-based, non-erosive ice (Van Liefferinge and Pattyn, 2013). The maximum age calculated for this landscape of 230 Ma (Paxman et al, 2016), based on minimal erosion rates (Cox et al, 2010), implies uplift of the GSMs much more recently than is otherwise suggested by detrital thermochronology of Prydz Bay marine sediments (van de Flierdt et al, 2008;Gupta et al, 2022) but potentially consistent with cooling histories of subglacial cobbles derived from the interior of East Antarctica (Fitzgerald and Goodge, 2022). The Prydz Bay sediments are presumed to have been sourced from the northern GSMs via the Lambert Graben; however, the valley network (Fig.…”

“…Several hypotheses have been proposed, including geologically recent thermal uplift associated with mantle hot spot activity (Sleep, 2006), ancient orogeny in a continental collision zone (Fitzsimons, 2000(Fitzsimons, , 2003Block et al, 2009), crustal shortening in response to long-distance stress transmission (Veevers, 1994) and uplift associated with rifting during continental breakup (Ferraccioli et al, 2011). Attempts have been made to date their formation using detrital materials of likely ancestral GSM provenance from coastal and offshore sediment deposits in the Prince Charles Mountains and Prydz Bay van de Flierdt et al, 2008;Gupta et al, 2022), producing ages generally in the ranges ca. 1200-800 Ma and ca.…”

“…620-460 Ma van de Flierdt et al, 2008), with another potential period of activity at ca. 700 Ma (Gupta et al, 2022). More recently, dates from intact rock clasts in the Transantarctic Mountains, which may have been transported there subglacially from the GSMs, indicate crustal formation spanning the period of ca.…”