Antonio Rodríguez-Perea

Tracks and trackways of Myotragus balearicus Bate (Artiodactyla, Caprinae) in Pleistocene aeolianites from Mallorca (Balearic Islands, Western Mediterranean)

Tracks and trackways of the ruminant goat, Myotragus balearicus Bate, 1909 are abundant in the Late Pleistocene aeolianites of the south coast of Mallorca, Spain. The carbonate aeolianites form impressive dunes and related sand ramps that were initiated as echo dunes in front of a 20–40 m high paleocliff of Miocene reefal limestone. Where the dunes built up to the cliff top, they covered it as an aeolian ramp. The dunes and sand ramps were active during the dry summer months but were passive during the wet winter period. The small, goat-like animals were abundant on the island, and for unknown reasons crossed the aeolian accumulations in large numbers. This study deals with the tracks formed in the dune deposits. All preserved trackways indicate impression into moist sand. Special features of the tracks include the structure produced by the withdrawal of the foot, here called the ‘axis’, and a disturbance zone of plastic deformation around this. On dune crests, the disturbance zone surrounds the axis more or less symmetrically. However, in addition, a ‘pressure pad’ of dislocated, slightly rotated sediment bound by curved microfaults is commonly produced posterior to the axis by propulsive pressure of the foot. On steep stoss and lee slopes, the pressure pad becomes oriented in a down-slope position as a result of gravitational slip of the walking animal. Combination of disturbance of the sediment in this way by manus followed by overprinting of similar disturbance by pes produces highly complicated track structure. This structure may be characteristic of artiodactylous mammals in soft sand, particularly aeolian deposits. The structure is designated as Bifidipes aeolis isp. nov.

A structural outline of the Serra de Tramuntana of Mallorca (Balearic Islands)

Abstract The structural and stratigraphic aspects of the Balearic Islands are described by outlining the geology of the Serra de Tramuntana. This range is part of the southeastern margin of the Valencia trough and has the typical features of thrust tectonic areas. A stratigraphic column, a structural map and three cross-sections show the main features of this range. Thrusts dip to the southeast and are arranged in an imbricate system with a transport direction to the NW. The thrusts recorded involve Upper Paleozoic to Middle Miocene rocks. Imbricates-bearing thin slices and duplexes developed where thin sequences with pronounced competency contrasts exist. Folds are also present: they usually trend NE-SW, except in local areas where they are interpreted as being associated with oblique ramps. Fold axes plunge sub-horizontally and folds face the northwest. Thrust displacements of up to 10 km are deduced from the existence of klippes and windows, and shortening of around 50% is deduced from a comparison of deformed and restored cross-sections. The onset of the main contractional event is pre-Miocene (probably Late Oligocene) in age, but major thrust emplacement occurred during the Middle Miocene. The widespread occurrence of compression structures in the Balearic Islands developed from late Oligocene to Middle Miocene put strong constraints on the models explaining the origin of both the Valencia trough and the Algerian basin. The first must be considered, at least in part, as the Balearic foreland basin and the second could be superimposed on the internal zone of the western Mediterranean orogenic belt.

Significance of Inherited Normal Faults during Inversion Tectonics: an example from the Tramuntana Range, Mallorca

The Late Oligocene-Middle Miocene Mallorca fold-and-thrust belt is characterised by a large amount of shortening above a detachment horizon. A regional section of 50 km in length across the island shows shortening of 80 km. Nevertheless, earlier normal faults play a significant role in compressive deformation. Two examples illustrating their role are presented: the first example is a fault-propagation-fold nucleated on a normal fault located in the fold core. We present a simple numerical model of this structure that illustrates how the observed complex structural and stratigraphic geometries might develop. The second example is a normal fault that interrupts the detachment level, giving rise to a step that results in a back-thrust system.

Beaches of Ibiza and Formentera (Balearic Islands): a classification based on their environmental features, tourism use and management

ABSTRACT Roig-Munar, F.X., Mir-Gual, M., Rodríguez-Perea, A., Pons, G.X., Martín-Prieto, J.A., Gelabert, B. and Blázquez, M., 2013. Beaches of Ibiza and Formentera (Balearic Islands): a classification based on their environmental features, tourism use and management, In order to define their character a total of 100 beaches of Ibiza (76) and Formentera (24) are analyzed on the basis of 35 variables of beach use, state and management. We take as a reference a primary classification where three types of beaches have been considered; urban beaches (A), semi-natural beaches with urban features (B), and natural beaches (C). Departing from this scenario, and taking into account the identified variables, statistical analysis (Cluster and PCA analysis) have been done in the sense of identifying the current state of each beach and the differences among them. Currently many of the beaches of Ibiza are urban beaches (A). Furthermore the results suggest a potential trend that some of natural beaches (B-C) can become to A type in the next future. Understanding this classification, and also the recent history of the management applied in the study units, allow predicting trend scenarios. In this sense, management changes should be proposed in order to improve their current situation, and drive them toward a better conservation status.

On the origin of the North Pacific arcs

We present a new hypothesis that relates global plate tectonics to the formation of marginal basins, island arcs, spreading ridges and arc-shaped mountain belts around the North Pacific Ocean. According to our model, the ellipsoidal-shaped Paleogene basins of the South China Sea, Parece-Vela Basin, Shikoku Basin, Sea of Japan and the Sea of Okhotsk in addition to those of the North American Cordillera can be attributed to the change in plate convergence direction at 42 Ma between the Indoaustralian and Eurasian plates. The new direction of convergence was parallel to the eastern continental margin of Asia and resulted in widespread extension perpendicular to this margin and to the western margin of North America. Both margins form part of a circle parallel to the Indoaustralian-Eurasian direction of convergence.

Coastal Management in the Balearic Islands

Coastal dunes represent important natural systems for balancing the beach while providing different functions such as protection against erosion and important ecological niches.

Environmental Analysis and Classification of Coastal Sandy Systems of the Dominican Republic

The Dominican Republic is the most visited insular tourist destination in the Caribbean, being its beaches its main attractiveness. This tourism generates 37% of the total revenues of the country, concentrated in coastal regions. As a result of this pressure, the coastal ecosystems are threatened by the increasing tourist development. Parameters such as site and dune morphology, beach condition, surface character of the seaward 200 m of the dune, pressure of use and recent protection measures make good regional comparison of beach-dune systems. A checklist was developed to calculate Vulnerability Index (VI) and Management Measures (MM) in 99 beach-dune systems of Dominican Republic allowing to identify and prioritize the different pressures. This method of study, associated with Geographical Information Systems (GIS), give more visibility to beach-dunes conditions, and by this facilitate the necessary decisions in the context of a sustainable management of coastal areas. The results indicate that the risk of beach erosion and degradation is directly related to the pressure of use of the coastal area.