Abstract The Betic and Rif cordilleras, lying to the north and south of the Alborán sea, form an arc-shaped mountain belt joining across the Straits of Gibraltar. The arc developed during, and partly in response to, late Mesozoic to Cenozoic convergence between Africa and Iberia. Three main pre-Miocene tectonic domains have been identified within the arc (Fig. 16.1a ). The first of these represents the palaeomargins of the southern part of the Iberian plate and the northern (Maghrebian) part of the African plate. Both palaeomargins comprise autochthonous, parautochthonous, and/or allochthonous non-metamorphic Mesozoic and Tertiary cover overlying a Variscan basement. These palaeomargins were deformed in response to Alpine events and now form the External Zones of the two cordilleras. The second major tectonic domain comprises deformed Cretaceous to Miocene deep-water ‘flysch’ sediments located in the western Betics and along the northern part of Africa from the Gibraltar Strait to the Kabylies (Fig. 16.1 ; e.g. Durand-Delga 1980 ). These ‘flysch’ sediments are thought to have been deposited in a basin located between the palaeomargins of Iberia and Africa and the rocks that form the internal part of the mountain belt ( Balanyá & García-Dueñas 1987 ). The third major tectonic unit is known as the Alborán domain or Internal Zones ( Balanyá & García-Dueñas 1987 ), and mainly comprises three nappe complexes of variable metamorphic grade, which are, from bottom to top, the Nevado-Filábride, the Alpujárride and the low-grade Maláguide complexes (Fig. 16.1 ). In addition, sedimentary rocks

Abstract Geological fluids are the major agents of transport of matter and heat in Earth dynamics. Unlike minerals, fluid density may vary by an order of magnitude, resulting in drastic changes in the molecular interactions. Water is a major fluid component, so it is essential to understand the response of hydrogen bonding with respect to pressure and temperature. In addition, geological fluids can be classified as complex chemical systems by a mixture of molecular compounds and ions. Thus, the study of aqueous solutions plays a fundamental role in understanding the behaviour of geological fluids. In the present chapter, focus is first placed on the use of Raman spectroscopy in the study of gases and how their spectral response changes under different pressure/temperature conditions. The ability of Raman spectroscopy to detect structural changes occurring in hydrogen-bonded systems, under thermodynamic conditions ranging from ordinary to extreme pressures and/or temperature is then discussed. Raman spectroscopy will be shown to provide invaluable information for a better understanding of the role played by geological fluids in Earth and crustal processes.