Analysis of Different GNSS Data Filtering Techniques and Comparison of Linear and Non-Linear Times Series Solutions: Application to GNSS Stations in Central America for Regional Geodynamic Model Determination

At present, different methods are used for processing GPS time series data obtained from a network of GNSS stations. Solutions converted to velocity and displacement allow the generation of different geodynamic models in areas influenced by tectonic and volcanic activity. This study focuses on the comparative analysis of the solutions obtained through different processing techniques: Precise Point Positioning (PPP) and Relative Positioning using specialized scientific software (Bernese 5.2). Another important objective of this study is the analysis of the convergence of linear and non-linear time series to determine the accuracy in each component (east, north, up), in addition to the application of statistical techniques and data filtering (1-sigma, 2-sigma, kalman, wavelets, and CATS analysis) to check the behavior of the series. These processing and analysis techniques will be applied to different series obtained from the main stations used for tectonic and volcanic monitoring in the Central America region (Guatemala, El Salvador, Honduras, Nicaragua, and Costa Rica) in order to establish a regional geodynamic model.

MAGMATOLOGICAL TECTONICS: ALFRED RITTMANN’S PARADIGM

ABSTRACT The aim of this research is to present the life and research of Alfred Rittmann (1893–1980). He was an Earth scientist in the broadest sense: a petrographer, mineralogist, magmatologist, tectonist, geodynamicist, planetologist, volcanologist and, what is more, a philosopher of geosciences. He is considered the founder of contemporary, volcanology by combining in his interdisciplinary research the study of volcanic phenomena at the surface with tectonic activity and magmatology. In his books, Rittmann discussed the first correlations between volcanism and tectonics; his geodynamic model comprises complex studies of geology, volcanology, magmatology and geodynamics. We propose to name his scientific worldview ‘Magmatological Tectonics’ (MT) and to describe it as a Kuhnian paradigm. The leading concept of all geological processes is the fundamental law. Rittmann also made abundant use of Chamberlin’s method, the method of multiple working hypotheses. Some brief interpretations will be proposed regarding the importance of Rittmann in the history of geosciences in the twentieth century and the emergence of some philosophical problems deriving from this research.

Tectono-metamorphic evolution of the continental units along the edge between Alpine and Hercynian Corsica

In this work the central area of Corsica island was studied in order to reconstruct the tectono-metamorphic history of the continental and oceanic high pressure units that occupy the structurally deeper levels of the tectonic stacking of Alpine Corsica and their stratigraphic and structural relationship with the European margin (Hercynian Corsica). The study includes the geological mapping, the mesoscale and microscale structural analysis, the acquisition of chemical analyzes and micromaps with the microprobe, thermobarometric estimation through specific methodologies for metapelites, U-Th-Pb dating of zircons and allanites. The results obtained allows to reconstruct the geodynamic model of this sector of the Alpine belt from the Permian to the Burdigalian.

The role of megacontinents in the supercontinent cycle

Supercontinent Pangea was preceded by the formation of Gondwana, a “megacontinent” about half the size of Pangea. There is much debate, however, over what role the assembly of the precursor megacontinent played in the Pangean supercontinent cycle. Here we demonstrate that the past three cycles of supercontinent amalgamation were each preceded by ~200 m.y. by the assembly of a megacontinent akin to Gondwana, and that the building of a megacontinent is a geodynamically important precursor to supercontinent amalgamation. The recent assembly of Eurasia is considered as a fourth megacontinent associated with future supercontinent Amasia. We use constraints from seismology of the deep mantle for Eurasia and paleogeography for Gondwana to develop a geodynamic model for megacontinent assembly and subsequent supercontinent amalgamation. As a supercontinent breaks up, a megacontinent assembles along the subduction girdle that encircled it, at a specific location where the downwelling is most intense. The megacontinent then migrates along the girdle where it collides with other continents to form a supercontinent. The geometry of this model is consistent with the kinematic transitions from Rodinia to Gondwana to Pangea.

Geodynamic Emplacement Setting of Late Jurassic Dikes of the Yana–Kolyma Gold Belt, NE Folded Framing of the Siberian Craton: Geochemical, Petrologic, and U–Pb Zircon Data

We present the results of geostructural, mineralogic–petrographic, geochemical, and U–Pb geochronological investigations of mafic, intermediate, and felsic igneous rocks from dikes in the Yana–Kolyma gold belt of the Verkhoyansk–Kolyma folded area (northeastern Asia). The dikes of the Vyun deposit and the Shumniy occurrence intruding Mesozoic terrigenous rocks of the Kular–Nera and Polousniy–Debin terranes were examined in detail. The dikes had diverse mineralogical and petrographic compositions including trachybasalts, andesites, trachyandesites, dacites, and granodiorites. The rocks showed significant similarities in distributions of REE, and their concentrations of most HFSEs were close to the intermediate ones between ocean islands basalts and enriched middle ocean ridge basalts. We propose that the subduction that was ongoing during the collision of the Kolyma–Omolon superterrane with Siberia led to melting in the asthenospheric wedge and in the lithosphere, which formed a mixed source for the dike systems from both an enriched and a depleted mantle source. The U–Pb SHRIMP-II dates obtained for the dikes corresponded to the Late Jurassic interval of 151–145 Ma. We present a geodynamic model for the northeastern margin of the Siberian Craton for the Tithonian age of the Late Jurassic.