Geofísica

The Ediacaran-Cambrian transition documents a critical stage in the diversification of animals. The global fossil record documents the appearance of cloudinomorphs and other shelled tubular organisms followed by non-biomineralized small carbonaceous fossils and by the highly diversified small shelly fossils between ~ 550 and 530 Ma.

The regional-residual separation of gravity anomalies in crustal and mineral exploration was a graphical-based procedure before the advent of fast digital computers and the need for more efficient algorithms to process large data sets. However, since requiring the supervision of an experienced interpreter, the results once obtained with graphical procedures are often accepted as second to none in producing anomalies with geological significance.

Dating archaeological materials is essential to understand time and rate of changes in different civilizations. For this purpose, different dating methods are used in several materials, including organic remains, sediments, and ceramics. Archaeomagnetic dating is a developing dating tool that has been improving rapidly due to the advances in geomagnetic model curves.

We developed a short-period Pn magnitude scale m_b(Pn) for earthquakes along the equatorial Mid-Atlantic Ridge. Due to low signal-to-noise ratios, teleseismic body wave magnitude and long-period surface wave magnitude cannot be confidently determined for small earthquakes of m_b < 4. Local magnitude scales are also not useful for these events because the oceanic environment does not allow the propagation of crustal phases.

The Neoproterozoic phosphogenic event records biotic and biogeochemical changes that seem to indicate intrinsic relationships between phosphogenesis and phosphatic fossil preservation. However, chemo-litho and biostratigraphic correlations conducted on fossiliferous, phosphatic successions of the Doushantuo Formation, South China, evidence a highly heterogeneous record, featuring diachronic depositional ages, variable taxonomic diversity and inconsistent, “noisy” δ¹³C records.

Commonly used speleothem-based paleoclimate proxies such as δ¹⁸O, δ¹³C, and trace element ratios are capable of high temporal resolution, but their interpretations are often ambiguous due to the conflated effects of multiple forcings. This complexity motivates the development of targeted proxies that can track specific local hydrological conditions. To this end, the concentration of ferromagnetic Fe-oxide particles in speleothem laminae has been suggested as a potential tracer for local precipitation.