Recent kinematics of the tectonic plates surrounding the Red Sea and Gulf of Aden

The Red Sea and Gulf of Aden represent two young basins that formed between Africa and Arabia since the early Oligocene, floored by oceanic crust or by transitional and thinned continental crust. While in the easternmost Gulf of Aden the rift–drift transition can be dated chron C6 (~20.1 Ma), here we show that in the Red Sea the first pulse of sea floor spreading occurred during chron C3n.2n (~4.6 Ma) around ~17.1°N (present–day coordinates) and propagated southwards from this location, separating the Danakil microplate from Arabia. It is also shown that sea floor spreading between Arabia and Nubia started later, around chron 2A (~2.58 Ma), and propagated northwards. At present, there is no magnetic evidence for the existence of a linear spreading center in the northern Red Sea at latitudes higher than ~24°N and in the southern Red Sea below ~14.8°N. The present–day plate kinematics of this region can be described with high accuracy by a network of five interacting plates (Nubia, Arabia, Somalia, Sinai, and Danakil) and six triple junctions. For times older than anomaly 2A (~2.58 Ma) and up to anomaly 3, the absence of marine magnetic anomalies between Arabia and Nubia prevents a rigorous kinematic description of the five–plates system. However, there is strong evidence that the unique changes in plate motions during the last five Myrs were a dramatic slowdown at chron C2 (~1.77 Ma) in the spreading or extension rates along the ridge and rift axes, thereby a good representation of the real plate motions can be obtained anyway by backward extension of the oldest Arabia – Nubia and Arabia – Danakil stage rotations determined on the basis of marine magnetic anomalies, respectively C2 – C2A and C2A – C3. The proposed kinematic reconstructions are accompanied by a geodynamic explanation for the genesis of large continent–continent fracture zones at the rift–drift transition and by an analysis of the strain associated with plate motions in Afar, northeastern Egypt, and Sinai

The opening of the Tyrrhenian basin and the Apennine chain formation in the kinematic context of Africa - Europe collision

EGU2020: Sharing Geoscience Online, 4-8 may 2020The Africa Europe collision, which produces the formation of the Alpine arc, in the Mediterranean area is accompanied by passive subduction processes, resulting from the sinking of the remnant Alpine Tethys and the Ionian lithosphere, and from the fragmentation of the Adriatic plate. In this complex deformation, back-arc basins (Alboran, Balearic, Tyrrhenian and Hellenic) and circum - Mediterranean mountain ranges are formed. In this work we focus our attention on the opening of the Tyrrhenian basin and the contemporary formation of the Apennine chain. In order to describe the evolution of the geodynamic processes that guided the formation of the Tyrrhenian basin and the Apennine chain we used the plate kinematics technique. Through careful observation of the regional structures we have divided the area of the Apennine Chain and the Tyrrhenian basin into polygons (crustal blocks or microplates) distinguished on the basis of the direction of the Tyrrhenian extension. The boundary between the polygons has been placed coinciding with the large structures that characterize the Tyrrhenian-Apennine area. The rotation poles of the individual polygons, in the frame of reference of the Sardo-Corso block, are based on the Tyrrhenian extension directions that characterize them. The velocity ratio between the polygons was determined by the slip vector of the structure (plate boundary) that separates them. To determine the rotation time of the polygons we used the stratigraphic records of the syn-rift sequences, while the rotation angle of the polygons is obtained comparing the crustal balance with the speed ratios. Finally, the kinematic framework obtained, included in the global rotation model, allowed us to reconstruct the tectonic evolution of the central Mediterranean during the opening of the Tyrrhenian basin

Geo-environmental changes and historical events in the area of the Greek archaeological site of Selinunte (Western Sicily, Italy)

Detailed geomorphological and geo-archaeological surveys were carried out in this study at the Greek archaeological site of Selinunte to reconstruct the landscape evolution that occurred before and during the anthropization of the site and to verify the possible correlations between geo-environmental changes and human events that characterized almost four centuries of the history of the city. By using a multidisciplinary approach and different survey techniques, this study testified the role played by climate, geomorphological setting and georesources in conditioning the development of the city and the close relationship sometimes observed between the historical events and natural processes. This included the controversial and never discovered hydraulic work of Empedocles who, according to textual sources, in 444 BC, resolved a public health problem linked to the presence of marshy areas

Controls of Radiogenic Heat and Moho Geometry on the Thermal Setting of the Marche Region (Central Italy): An Analytical 3D Geothermal Model

none7sìopenSantini, S.; Basilici, M.; Invernizzi, C.; Jablonska, D.; Mazzoli, S.; Megna, A.; Pierantoni, P.P.Santini, S.; Basilici, M.; Invernizzi, C.; Jablonska, D.; Mazzoli, S.; Megna, A.; Pierantoni, P. P

A New Southern North Atlantic Isochron Map: Insights Into the Drift of the Iberian Plate Since the Late Cretaceous

This paper presents a new southern North Atlantic plate model from Late Cretaceous to present, with the aim of constraining the kinematics of the Iberian plate during the last 83.5 Myr. This model is presented along with a detailed isochron map generated through the analysis of 3 aeromagnetic tracks and ~400 ship tracks from the National Centers for Environmental Information database. We present a new technique to obtain well‐constrained estimates of the Iberia‐North America plate motions from magnetic anomalies, overcoming the scarcity of large‐offset fracture zones and transform faults. We build an integrated kinematic model for NW Africa, Morocco, Iberia, Europe, and North America, which shows that the deformation is partitioned between Pyrenees and Betic‐Rif orogenic domain during the Late Cretaceous‐Oligocene time interval. In the Eastern Betics domain, the calculated amount of NW Africa‐Iberia convergence is ~80 km between 83.5 and 34 Ma, followed by ~150 km since the Oligocene. The motion of Iberia relative to Europe in the Central Pyrenees is characterized by overall NE directed transpressional motion during the Campanian and the Paleocene, followed by NW directed transpressional movement until the Lutetian and overall NNW directed convergence from Bartonian to Chattian. This motion occurs along the axis of the Bay of Biscay from the Santonian–Campanian boundary to the middle Priabonian, subsequently jumping to King's Trough at Anomaly 17 (36.62 Ma)

Stratigraphic framework of the late Miocene Pisco Formation at Cerro Los Quesos (Ica Desert, Peru)

The enormous concentration of marine vertebrates documented within the Pisco Formation is unique for Peru and South America and places this unit among the prime fossil Lagerstätten for Miocene to Pliocene marine mammals worldwide. In order to provide a robust stratigraphic framework for the fossil-bearing locality of Cerro Los Quesos, this study presents a 1:10,000 scale geological map covering an area of about 21 km2, a detailed measured section spanning 290 m of strata, and a refined chronostratigraphy for the studied succession well constrained by diatom biostratigraphy and high-resolution 40Ar/39Ar isotopic dating of three interbedded ash layers. Within the apparently monotonous, diatomite-dominated sedimentary section, the Pisco Formation has been subdivided into six local members, with stratigraphic control over the different outcrops facilitated by the establishment of a detailed marker bed stratigraphy based on fifteen readily distinguishable sediment layers of different nature