Geodynamic Setting of La Réunion

Abstract

The island of La Réunion is located in the complex oceanic environment of the Marscarene Basin. The latter was created by oceanic expansion between the late Cretaceous and the Paleocene. The expansion of the Basin stopped at magnetic chron 27 when the spreading jumped north, between the Seychelles and India, to become the Central Indian Ridge. Dating and geodynamic reconstructions support a hot spot origin for La Réunion volcanism. La Réunion lies in the middle of an approximately 350 km-wide zone bounded by transform faults (Mauritius and Mahanoro-Wilshaw Fracture Zones) and a trough identified as the extinct spreading center (chron 27). This compartment exhibits a substantial depth anomaly (several hundreds of meters), possibly related to the interaction with the hot spot plume. Gravity and seismic data show the virtual absence of flexure beneath and around La Réunion. Near La Réunion the organization of the oceanic crust magnetic anomalies is very different from the classic parallel striped oceanic organization. It has been suggested that this pattern might be interpreted in terms of a paleo-triple junction of oceanic rifts. Many seamounts protrude from the sediments in the La Réunion segment, some associated with the transform faults, others associated with a series of parallel ridges and a few isolated others. All these constructions postdate the oceanic crust, but most of them appear to be much older than La Réunion, with the possible exception of some small seamounts close to La Réunion or on its submarine flanks. Regional Tectonic SettingThe Indian Ocean started to open up around 175 Ma (Schettino and Scotese 2005). The early stages of Gondwanan break-up separated Africa from a block composed

The August 2019 Piton de la Fournaise (La Réunion Island) Eruption: Analysis of the Multi-Source Deformation Pattern Detected through Sentinel-1 DInSAR Measurements

“…La Réunion Island, located east of Madagascar (SW Indian Ocean; Figure 1a), is characterized by a NW-SE-trending elliptical shape (Figure 1b). It is inserted in the largescale geodynamic environment of the Indian Ocean and in the complex tectonic setting of the Marscarene Basin, generated by the oceanic expansion that occurred between the late Cretaceous and the Paleocene [15]. Several authors [14][15][16]25] agree in attributing a hot-spot origin to La Réunion volcanism.…”

“…The emerged part of the island corresponds to a small portion (about 4%) of the entire volcanic edifice, which presents a basal diameter of about 240 km and reaches more than 7000 m above the abyssal plain [15]. La Réunion Island can be considered the result of the overlap of two large basaltic shield-volcanoes, Piton des Neiges and Piton de la Fournaise (Figure 1b).…”

“…Piton de la Fournaise is a hot-spot basaltic volcano located on the southeastern part of La Réunion Island and inserted in the tectonic framework of the Indian Ocean [14][15][16][17] (Figure 1a-c). Thanks to the establishment of the Observatoire Volcanologique du Piton de la Fournaise (OVPF) in 1980, this volcano has been extensively studied by using and integrating geological, petrological, geochemical, geodetic, and geophysical monitoring approaches [17][18][19][20].…”