Geofísica

NMR is widely applied in Materials Science for the characterization of porous materials. The advantage of this technique is the high correlation between the NMR measurements and the physical-chemical features of the material. Magnetic susceptibility is one of many other properties that have been investigated by time domain NMR. In this work, the study of the influence of magnetic susceptibility on the relaxation process of micro and macroporosity is carried out, which is obtained using the T2-filtered and T1-weighted techniques combined with the CPMG experiment.

Surface wave tomography is considered an efficient method to reveal the physical properties of subsurface geological structures, particularly beneath geologically complex areas where conventional active seismic methods are problematic. The salt-rich DehDasht structural basin, in the SW of Iran, is an example of this area, which is characterized by high seismicity. Despite the complex geology and the great thickness of evaporitic deposits in this region, surface wave tomography can retrieve high-resolution images by applying a dense network of stations.

Extensive phosphorite deposition is observed in the Neoproterozoic after a prolonged hiatus during most of the Mesoproterozoic era. This event is thought to represent an important record of major palaeoenvironmental, palaeoceanographic and biotic changes that shaped Neoproterozoic ecosystems, suggesting close relationships between phosphogenesis and the preservation of key Ediacaran biotas.

The Mesozoic Dipole Low (MDL), when the mean geomagnetic field intensity did not exceed one-third of the mean value in the Late Cenozoic, was suggested from the end of the Early Jurassic to the 

The Ediacaran Period was an interval of significant global transformation, marked by major changes in the biosphere, cryosphere, hydrosphere and atmosphere, and possibly the solid Earth. A better understanding of this interval is thus important to an understanding of the diversification of complex life, the history of long-term climatic change and the evolution of global geochemical cycles. Increasingly detailed temporal records are being acquired from Ediacaran rocks to investigate these changes in time, but we still lack a robust paleogeographic framework to study them in space.

The Ediacaran apparent polar wander path (APWP) for the Rio de la Plata Craton was analyzed and a new alternative path is presented. This revised path was constructed considering an opposite polarity for poles older than ca. 590 Ma. This path is more consistent with that recently proposed for West Africa, whose large oscillations were attributed to two events of inertial interchange true polar wander (IITPW). A compilation and selection of Ediacaran paleomagnetic data from the main cratons were analyzed leading to a set of global paleogeographic reconstructions throughout the Ediacaran.

An innovative inversion code, named “Curupira v1.0”, has been developed using Matlab to determine the vertical distribution of resistivity beneath the subsoil. The program integrates Vertical Electrical Sounding (VES), successful in shallow subsurface exploration and Time Domain Electromagnetic (TEM) techniques, better suited for deeper exploration, both of which are widely employed in geophysical exploration. These methodologies involve calculating subsurface resistivity through appropriate inversion processes.

This work is the first attempt to simulate experimentally the impact of underplating high-Ti basaltic melt from Paraná-Etendeka Magmatic Province (PEMP) on a pre-existing continental crust. Our final aim is to unravel the origin of high volumes of high-Ti Chapecó dacitic melts. A campaign of three new chaotic mixing experiments was performed starting from a natural basaltic melt composition (i.e., high-Ti Pitanga-type) while solely varying the chemical composition of rhyolitic end-member (i.e., the contaminant).

Quantifying the contributions of distinct mineral populations in bulk magnetic experiments greatly enhances the analysis of environmental and rock magnetism studies. Here, we develop a new method of parametric unmixing of susceptibility components in hysteresis loops. Our approach is based on a modified Gamma-Cauchy exponential model that accounts for variable skewness and kurtosis. The robustness of the model is tested with synthetic curves that examine the effects of noise, sampling, and proximity (similar coercivities) of susceptibility components.

Magnetostratigraphy is a powerful technique for high-resolution stratigraphic correlation and accurate dating of the polarity history of the magnetic field. Up to now, magnetostratigraphic studies have been underutilized in Ediacaran successions. Here, we present a magnetostratigraphy coupled with a carbon isotope study in Ediacaran Avellaneda Formation (∼570 Ma), a sedimentary cover sequence in the Tandilia orogenic belt, of the Río de la Plata craton.