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This article includes a review of the structure and evolution of the Antarctic Earth crust (the Antarctic continent and the Southern Ocean) from the Archean to the Late Cenozoic, accompanied by the sketch of Antarctic tectonic provinces. It is based on the long-term research and preparation of the second edition of the Tectonic Map of the Antarctica at a scale of 1 : 10 000 000 with a detailed explanatory note in the International Commission for the Geological Map of the World. In the course of the work a large volume of geological and geophysical data of Russian Antarctic expeditions and expeditions of other countries were combined, analyzed, and interpreted, first of all, the data of geochemical and geochronological studies of rock specimens from outcropped regions and numerous geophysical surveys in the Southern Ocean. The structure and tectonic history of the Archean cratons and Proterozoic orogens of East Antarctica (with indication of the controversial issues of Precambrian evolution), the orogens of the Pacific margin, intraplate fold systems, continental margins, and the early sea floor spreading are considered. [ABSTRACT FROM AUTHOR]

The mountain framework of the Denman Glacier is a poorly explored area. However, it is a key region of East Antarctica in the context of studying the Precambrian geological history and geodynamic evolution of the Archean protocratons of the Antarctic Shield and in their comparison with the Archean crust-forming events of other regions of the Earth. Original U–Pb isotope geochronology data from zircons of metamorphic and intrusive rocks sampled from the western side of the Denman Glacier are reported. A geotectonic interpretation of the data was carried out. The Paleoarchean age of crystallization (3355 ± 5.4 Ma) of the magmatic protolith of tonalitic orthogneisses of the Davis granite–gneiss complex was obtained for the first time in this sector of Antarctica. In the Archean time interval, the Davis Paleoarchean protocraton was affected by multistage polymetamorphism in the intervals ~3100–3000 and 2900–2800 Ma ago. A crustal extension associated with the late stage is indicated by syntectonic intrusion of ultramafic dikes and pyroxenite sills (2827 ± 6 Ma). The time when granite veins and subalkaline granitoid plutons formed corresponds to the time of tectono-thermal Pan-African activization in the interval of 550–510 Ma typical for the Rayner Province of East Antarctica. The terrane of Davis craton is similar to the Paleo-Mesoarchean protocratons of East Antarctica, India, and Australia for the time of formation and the evolution of geodynamic processes. [ABSTRACT FROM AUTHOR]

This paper presents a complex interpretation of structural–petrological studies and new geochemical and isotope–geochronological data on the Paleoarchean metamorphic and metaintrusive rocks of Mts. Rymill and Bloomfield in the northern part of the granite-greenstone Ruker terrane (Prince Charles Mountains, East Antarctica). The detailed sequence of changing Archean tectonomagmatic processes in the northern block of the Ruker area has been revealed and the main stages of tectonic deformations and metamorphism of Precambrian geodynamic evolution are shown, which is a key for the understanding of the geological evolution of the Archean metamorphic complexes of East Antarctica and ancient Earth's regions. The northern part of the Ruker Terrane is composed of the Meso-Neoarchean granite–gneiss domes, which are tectonically framed by fragments of greenstone belt of the metavolcanosedimentary Meso-Neoarchean Menzies Series. The detached blocks or packages of sheets of metavolcanosedimentary sequences are a section of weakly metamorphosed intermediate–felsic sandstones, quartzites, and micaceous schists. An assemblage of rocks spans a significant period from 3.2 to 2.5 Ga. The composition of the Mesoarchean granite–gneiss domes of the Mawson Series (3.2–3.1 Ga) corresponds to those of ancient granitoids, is similar to tonalite–trondhjemite–granodiorite (TTG) complexes, and is comparable with similar associations of ancient cratons of Australia, Canada, and Fennoscandia. The rocks of the Mawson Series are polymetamorphic and a significant part of their recrystallization is related to the Mesoarchean stage of metamorphism, whose end is comparable with the formation of the Meso-Neoarchean blocks of the granite–gneiss association of the TTG dome of ~2.8 Ga identified by the author. The age of the striking tectonothermal event of ~2.7 Ga is determined by overgrowths of zircons from the TTG gneisses. The Mawson Orthogneiss and TTG gneisses are compared with intraplate A‑granitoids and are ascribed to low-Ti high-K Archean granitoids. The geochemistry of the rocks indicates that primary melts of the Meso-Archean Mawson Orthogneiss formed in crust at shallower depths (P < 8–10 kbar) in comparison with Meso-Archean TTG gneisses, whose formation is possibly caused by the increasing thickness of the crust followed by its extension and thinning at a boundary of ~2.5 Ga. [ABSTRACT FROM AUTHOR]

Abstract–In order to determine the paleointensity of the geomagnetic field in the Precambrian, a collection of rocks from 83 samples of 19 sites selected from the Mesoproterozoic (1133 Ma) dikes of the Bunger Oasis (East Antarctica) was studied. The magnetic and thermomagnetic properties of rocks have been studied in details, the domain structure of magnetic grains, carriers of natural remanent magnetization, has been evaluated, and micromagnetic and X-ray studies have been carried out. It is shown that the carriers of the characteristic component of natural remanent magnetization are single- and/or small pseudo-single-domain grains. Paleointensity was determined by the Thellier-Coe method with the check-points procedure and, in addition to it, the express Wilson method. For 11 sites, low to extremely low values of paleointensity Banc were obtained, which meet modern reliability criteria, the main array of Banc determinations by sites is grouped around (1.5–5) μT. The calculated values of the virtual dipole moment VDM vary from 3 to 8 (×1021 Am2), which is an order of magnitude (and more) less than the current VDM value. Such low values of paleointensity do not agree with the hypothesis of an increased intensity of the geomagnetic field in the Middle Proterozoic and testify against the hypothesis of the formation of the Earth's inner core in the time interval from 1.5 to 1 Ga ago. An analysis of the VDM values presented in 2022 in the world database over the interval of 3600–500 Ma showed that the behavior of the geomagnetic field in the Precambrian is characterized by the alternation of long periods of low and high intensity with a tendency to its gradual weakening from the Archean to the Neoproterozoic. A linear approximation of such a dependence of the VDM value on time has a correlation coefficient of 0.22 at a confidence level of 0.98. The noted features of the behavior of the intensity of the geomagnetic field in the Proterozoic and Paleozoic testify in favor of the hypothesis of the origin of the Earth's solid core not earlier than the Late Neoproterozoic. [ABSTRACT FROM AUTHOR]

In an effort to improve our understanding of the seismic character of the crust beneath southeast Australia and how it relates to the tectonic evolution of the region, we analyse teleseismic earthquakes recorded by 24 temporary and 8 permanent broadband stations using the receiver function method. Due to the proximity of the temporary stations to Bass Strait, only 13 of these stations yielded usable receiver functions, whereas seven permanent stations produced receiver functions for subsequent analysis. Crustal thickness, bulk seismic velocity properties, and internal crustal structure of the southern Tasmanides – an assemblage of Palaeozoic accretionary orogens that occupy eastern Australia – are constrained by H – κ stacking and receiver function inversion, which point to the following: a ∼ 39.0 km thick crust; an intermediate–high Vp/Vs ratio (∼ 1.70–1.76), relative to ak135; and a broad (> 10 km) crust–mantle transition beneath the Lachlan Fold Belt. These results are interpreted to represent magmatic underplating of mafic materials at the base of the crust. a complex crustal structure beneath VanDieland, a putative Precambrian continental fragment embedded in the southernmost Tasmanides, that features strong variability in the crustal thickness (23–37 km) and Vp/Vs ratio (1.65–193), the latter of which likely represents compositional variability and the presence of melt. The complex origins of VanDieland, which comprises multiple continental ribbons, coupled with recent failed rifting and intraplate volcanism, likely contributes to these observations. stations located in the East Tasmania Terrane and eastern Bass Strait (ETT + EB) collectively indicate a crust of uniform thickness (31–32 km), which clearly distinguishes it from VanDieland to the west. Moho depths are also compared with the continent-wide AusMoho model in southeast Australia and are shown to be largely consistent, except in regions where AusMoho has few constraints (e.g. Flinders Island). A joint interpretation of the new results with ambient noise, teleseismic tomography, and teleseismic shear wave splitting anisotropy helps provide new insight into the way that the crust has been shaped by recent events, including failed rifting during the break-up of Australia and Antarctica and recent intraplate volcanism. [ABSTRACT FROM AUTHOR]

The information on the composition, structure, P-T conditions of metamorphic facies, evolution, and time of the metamorphic events in the largest Precambrian tectonic provinces of the Antarctic Crystalline Shield gained over more than a half-century is summarized in this paper. The joining up of the ortho- and paracrystalline rocks into complexes and groups according to their geographic position, composition, age, and the character of their metamorphism allowed us to consider the main features of the structure and evolution of the provinces including (1) the near-latitudinal polycyclic Late Precambrian-Early Paleozoic Wegener-Mawson Mobile Belt, extended for more than 4000 km, which started to evolve in the Mesoproterozoic and stabilized only at the end of Cambrian; (2) the Early Precambrian relict crystalline protocratonic blocks adjoining this mobile belt; their history is traced from the Eoarchean; and (3) the near-latitudinal Late Precambrian-Early Paleozoic aulacogen in the southern protocratonic block. The P-T conditions of the metamorphism from the pyroxene-granulite subfacies in the protocratonic blocks to the greenschist facies in aulacogen, as well as the age of the magmatic and metamorphic events in all the tectonic provinces of the shield, are characterized. This made it possible to consider the metamorphic history and conditions of the continental crust's formation in Antarctica, where the oldest crystalline rocks are dated to the Eoarchean (4060-3850 Ma) and the youngest rocks are ∼500 Ma old. [ABSTRACT FROM AUTHOR]

Abstract: The Southern Prince Charles Mountains (SPCM) are mostly occupied by the Archaean Ruker Terrane. The Lambert Terrane crops out in the northeastern part of the SPCM. New geochemical and zircon U–Pb SHRIMP ages for felsic orthogneisses and granitoids from both terranes are presented. Orthogneisses from the Ruker and Lambert terranes differ significantly in their major and trace-element compositions. Those from the Ruker Terrane comprise two distinct groups: rare Y-depleted and abundant Y-undepleted. U–Pb isotopic data provide evidence for tonalite−trondhjemite emplacement at 3392±9 and 3377±9 Ma, pre-tectonic granite emplacement at 3182±9 Ma, metamorphism(?) at c. 3145 Ma, and thermal events at c. 1300(?) and 626±51 Ma. The Lambert Terrane orthogneisses probably originated in a continental magmatic arc. Zircon dating shows a very different geological history: pre-tectonic granitoid emplacement at 2423±18 Ma, metamorphism at 2065±23 Ma, and syn-tectonic granitoid emplacement at 528±6 Ma, syn-tectonic pegmatite emplacement at 495±18 Ma. The Lambert Terrane can be correlated with neither the Meso- to Neoproterozoic Beaver Terrane in the Northern PCM, which differs in isotopic composition, nor with the Archaean Ruker Terrane, which differs in both granitoid chemical composition and the timing of major geological events. It represents a Palaeoproterozoic orogen which experienced strong tectonic re-activation in Pan-African times. The Lambert Terrane has some geochronological features in common with the Mawson Block, which comprises south Australia and some areas in East Antarctica. [Copyright &y& Elsevier]