Tectonic Subdivision of the Prince Charles Mountains: A Review of Geologic and Isotopic Data

Abstract

Abstract. The Prince Charles Mountains have been subject to extensive geological and geophysical investigations by former Soviet,Russian and Australian scientists from the early 1970s. In this paper we summarise, and review available geological and isotopic data, and report results of new isotopic studies (SmNd, Pb-Pb, and U-Pb SHRIMP analyses); field geological data obtained during the PCMEGA 2002/2003 are utilised. The structure of the region is described in terms of four tectonic terranes. Those include Archaean Ruker, Palaeoproterozoic Lambert, Mesoproterozoic Fisher, and Meso-to Neoproterozoic Beaver Terranes. Pan-African activities (granite emplacement and probably tectonics) in the Lambert Terrane are reported. We present a summary of the composition of these terranes, discuss their origin and relationships. We also outline the most striking geological features, and problems, and try to draw attention to those rocks and regional geological features which are important in understanding the composition and evolution of the PCM and might suggest targets for further investigations. Previous WorkThe Prince Charles Mountains (PCM) constitute by far the best exposed cross section through the East Antarctic Shield, extending for over 500 km along the drainage basin of the Lambert Glacier -Amery Ice Shelf system (Fig. 2.7-1). Australian geologists first visited this region between 1955 and 1957. The results of geological observations were presented by Stinear (1956) and Crohn (1959), who recorded in the northern PCM (NPCM) a range of high-grade metamorphic rocks of both sedimentary and igneous origin, as well as orthopyroxene granitoids, and an overlying coal-bearing Permian-Triassic sedimentary sequence. Geological investigations in the southern PCM (SPCM) showed that the rocks there are generally of much lower metamorphic grade (green-schist to amphibolite facies) than those of the NPCM; they include thick metasedimentary sequences and are cut by abundant mafic dykes. The early workers (Tingey 1982(Tingey , 1991, and references therein), on the basis of numerous Rb-Sr ages, reported the PCM as comprising two major tectonic provinces roughly corresponding to the two parts of the mountain range (NPCM and SPCM). One of the most interesting results of this study (Tingey 1982(Tingey , 1991 was the recognition that presumed granitic basement and overlying metasediments in the SPCM were of Archaean age (whole-rock Rb-Sr isochrons 2 700 ±90, 2 750 ±400, and 2 760 ±200 Ma), whereas granulite-facies rocks of the NPCM were Meso-to Neoproterozoic (whole-rock Rb-Sr isochrons from 769 ±36 to 1033 ±85 Ma). This was at variance with earlier ideas that the higher-grade rocks were likely to be older (e.g., Solov ev 1972). Muscovite-bearing pegmatites cutting the metasediments in the SPCM were dated at 2 589, 2 100, 1 995, and 1 708 Ma, and it was suggested that Palaeoproterozoic, as well as Archaean sequences may be present. A few imprecise Mesoproterozoic isochron ages were also obtained (ca. 1 170 ±230, 1 400 ±150 Ma); these w...

Major and Trace-Element Chemistry of Cr-Spinel in Upper Mantle Xenoliths from East Antarctica

“…1400-1000 Ma or ca. 580-500 Ma; see [6,13] and references therein). The precise timing of such reactivation is not clear yet, but it could have happened between the infiltration of the MORB-like melts incorporation of the xenoliths to the ascending host magma (150-140 Ma [1]).…”

“…The difference in composition and lithology of the xenoliths found in the ca. 580-500 Ma through continental collision (see [6,13] and references therein). In either scenario, the continental crust and the SCLM beneath the region are not homogeneous [14,15].…”

Geophysical Evidence of the Collisional Suture Zone in the Prydz Bay, East Antarctica

“…This region is characterized by the convergence of three prominent Precambrian cratons, namely East Antarctica, Africa, and Australia (Fitzsimons, 2000b). The geological imprints of tectonic evolution during the Neoproterozoic‐Early Paleozoic period have been preserved in this area, making the Prydz Bay area pivotal for understanding the formation and evolution of the supercontinent Gondwana (Boger et al., 2001; Harley, 2003; Mikhalsky et al., 2006; Tingey, 1991). It is widely accepted that this region represents a Proterozoic continental suture, potentially connected to the Darling orogenic belt in Western Australia toward the northeast, with potential extensions to the northern margin of the Indian plate (Fitzsimons, 2000a).…”

Geophysical Evidence of the Collisional Suture Zone in the Prydz Bay, East Antarctica

“…This region is characterized by the convergence of three prominent Precambrian cratons, namely East Antarctica, Africa, and Australia (Fitzsimons, 2000b). The geological imprints of tectonic evolution during the Neoproterozoic-Early Paleozoic period have been preserved in this area, making the Prydz Bay area pivotal for understanding the formation and evolution of the supercontinent Gondwana (Boger et al, 2001;Harley, 2003;Mikhalsky et al, 2006;Tingey, 1991). It is widely accepted that this region represents a Proterozoic continental suture, potentially connected to the Darling orogenic belt in Western Australia towards the northeast, with potential extensions to the northern margin of the Indian plate (Fitzsimons, 2000a).…”