Marek Lewandowski

Compared to other continents, Antarctica suffers from a poverty of geophysical data that would allow for a better understanding of its geological structure, as well as isostatic response of the continent to the volumetric change of the ice cover. Antarctica, and in particular its rocky unhabituated oases, could be utilized for the installation of geophysical, autonomous devices that would measure and record unique seismic (both volumetric and surface) waves, gravimetric, geomagnetic (including magnetotelluric) or ionospheric data, not handicapped by an impact from anthropogenic sources. Such data could significantly contribute to our understanding of the Earth's internal structure, from the core, through the structure of the mantle and crust, to the dynamics of glaciers as well as ionospheric processes that are related to space weather effects.An example is the rocky oasis of Bunger Hills, located in the Australian part of the Southern Ocean and several dozen kilometres away from the Ocean. During the IVth Polish Antarctic Research Expedition to the Antoni B. Dobrowolski Station (located in the central part of the oasis), test geophysical measurements in the fields of seismology, meteorology, geomagnetism, and ionosphere research were carried out in the summer of 2021/2022. The results obtained are of high quality and clearly indicate the potential of the Dobrowolski Station for the location of autonomous and automatic geophysical stations providing measurement data to global databases. Since the Station is equipped with a concrete pole, built in 1958/59 for gravimetric measurements (see: https://www.ats.aq/devph/en/apa-database/126), it also could be used for isostatic movements of the Antarctic crust as the ice cover recedes.Given expansion of EPOS ERIC beyond the continental Europe, the Dobrowolski Station would be a strong node in the Antarctic geophysical infrastructure network, providing high-quality recordings to topical data exchange platforms (Thematic Core Services - TCS) within EPOS ERIC, as well as to other global data centers.

Najbardziej niezwykła rzecz we Wszechświecie kryje się w twojej głowie. Bill Bryson

The Rodinia supercontinent broke apart during the Neoproterozoic. Rodinia break-up is associated with widespread intraplate magmatism on many cratons, including the c. 720–719 Ma Franklin large igneous province (LIP) of Laurentia. Coeval magmatism has also been identified recently in Siberia and South China. This extensive magmatism terminates ∼1 myr before the onset of the Sturtian Snowball Earth. However, LIP-scale magmatism and global glaciation are probably related. U–Pb isotope dilution–thermal ionization mass spectrometry (ID-TIMS) baddeleyite dating herein identifies remnants of a new c. 724–712 Ma LIP on the eastern Kalahari Craton in southern Africa and East Antarctica: the combined Mutare–Fingeren Dyke Swarm. This dyke swarm occurs in northeastern Zimbabwe (Mutare Dyke Swarm) and western Dronning Maud Land (Fingeren Dyke Swarm). It has incompatible element-enriched mid-ocean ridge basalt-like geochemistry, suggesting an asthenospheric mantle source for the LIP. The Mutare–Fingeren LIP probably formed during rifting. This rifting would have occurred almost ∼100 myr earlier than previous estimates in eastern Kalahari. The placement of Kalahari against southeastern Laurentia in Rodinia is also questioned. Proposed alternatives, invoking linking terranes between Kalahari and southwestern Laurentia or close to northwestern Laurentia, also present challenges with no discernible resolution. Nevertheless, LIP-scale magmatism being responsible for the Sturtian Snowball Earth significantly increases.

In this study, we investigated the geomagnetic ground observatory data from 1980 to 2011 collected from World Data Center from 134 stations. To analyze the data we have applied spherical harmonic decomposition to obtain components associated with the Earth’s main magnetic field and to calculate how the Earth’s dipole was varying in the aforementioned recent 31-year period. There is a visible ~ 2.3% decay of the dipole magnetic field of the Earth. We note that the present-day value of the magnetic dipole intensity is the lowest one in the history of modern civilization and that further drop of this value may pose a risk for different domains of our life.

Natural mineral particulate matter deposited from aerosols and trapped in glaciers—herein defined as “cryodust”—may be an excellent indicator of atmospheric circulation, if terrestrial sources of dust can be identified. In this study, we analyzed the composition of cryodust in shallow ice cores taken from five glaciers in Southern Spitsbergen (Svalbard Archipelago, Northern Norway). The chemical composition, magnetic properties and radiogenic ages of individual grains were measured, where possible, to provide indicators of source areas. To identify mineral and rock fragments, solid particulates were examined by Scanning Electron Microscope fitted with a backscattered electron and Energy Dispersive Spectroscopic detectors. An Electron MicroProbe was employed for the U-Th-Pb chemical dating of monazite grains. Magnetic measurements comprised analyses of magnetic susceptibility (κ) vs. temperature (T) variations and determination of magnetic hysteresis parameters. Monazite ages span 445–423 Ma, consistent with mineral growth during the Caledonian orogeny. Caledonian rocks are exposed in the Nordaustlandet area of North-Eastern Svalbard, and this is the most probable source for monazite grains. Magnetic analyses show a predominance of ferrous (Fe^II) over ferric (Fe^III) phases, consistent with a lack of input from subtropical sources. The results from both methods are consistent with local sources of dust from exposures in the Svalbard archipelago.

On the nature of the Teisseyre-Tornquist Zone

The Teisseyre‐Tornquist Zone (TTZ) is generally regarded as a fossil plate boundary in Europe that extends 2000 km from the Baltic Sea to the Black Sea. We used an integrated approach merging potential fields and seismic data to explore crustal architecture across the TTZ in central Poland. The aim of the study was to test whether the TTZ coincides with an early Paleozoic (Caledonian) suture formed through the closure of the Tornquist Ocean along the SW Baltica margin. The suture is presumed to separate the East European Craton (EEC) from the Paleozoic terranes of Western Europe. Two seismic reflection lines from the PolandSPAN™ experiment were used to image the deep structure at the SW margin of the EEC. Lines PL‐5300 and PL‐5400 run NE‐SW in central and northern Poland, respectively. The seismic interpretation down to top of basement was integrated with 2‐D gravity and magnetic modeling to highlight the structure of the deep crust. Both the gravity and magnetic models show a suture that welds together two blocks at the base of crust. However, top of basement above the suture dips uniformly to the SW and is overlain by undisturbed lower Paleozoic and younger sediments. By implication, the suture must have developed in the Precambrian and both crustal blocks amalgamated belong to the EEC. Consequently, the Caledonian suture, formed by the closure of the Tornquist Ocean between Avalonia and Baltica, must be located farther southwest beneath thick upper Paleozoic and Mesozoic sediments.