We investigate the anisotropic nature of the mantle in a part of the Arabia-Eurasia collision zone where several of the constituent tectonic blocks of Iran come into contact. Our aim is to identify the dominant source of anisotropy in order to infer the pattern of mantle deformation as it responds to the forces of continental convergence.
The broadband seismic data used in this study were recorded by 68 seismic stations in three temporary arrays in NW Iran (between 45º00'E - 51º00'E and 35º00'N - 39º00'N) installed and operated non-concurrently between 2008 and 2016 by the Institute for Advanced Studies in Basic Sciences (IASBS) and the University of Cambridge, and one permanent station of the Iranian National Seismic Network (INSN). The stations were repositioned during deployment and the recording span at individual stations varied between 4 and 31 months. The temporary arrays were mainly linear profiles that traversed the Talesh and western Alborz Mountains, NW Iran, and parts of the central Iran Plateau to the vicinity of the UDMA.
Our dataset includes seismic records of S and SK(K)S phases. For the SK(K)S splitting measurements we used teleseismic earthquakes with magnitudes greater than 5.5 and epicentral distances between 90º and 130º, and for the direct S phase analysis we considered events larger than magnitude 5.5 in the distance range of 40º to 80º.
We investigate the anisotropic nature of the mantle in a part of the Arabia-Eurasia collision zone where several of the constituent tectonic blocks of Iran come into contact. Our aim is to identify the dominant source of anisotropy in order to infer the pattern of mantle deformation as it responds to the forces of continental convergence.
The broadband seismic data used in this study were recorded by 68 seismic stations in three temporary arrays in NW Iran (between 45º00'E - 51º00'E and 35º00'N - 39º00'N) installed and operated non-concurrently between 2008 and 2016 by the Institute for Advanced Studies in Basic Sciences (IASBS) and the University of Cambridge, and one permanent station of the Iranian National Seismic Network (INSN). The stations were repositioned during deployment and the recording span at individual stations varied between 4 and 31 months. The temporary arrays were mainly linear profiles that traversed the Talesh and western Alborz Mountains, NW Iran, and parts of the central Iran Plateau to the vicinity of the UDMA.
Our dataset includes seismic records of S and SK(K)S phases. For the SK(K)S splitting measurements we used teleseismic earthquakes with magnitudes greater than 5.5 and epicentral distances between 90º and 130º, and for the direct S phase analysis we considered events larger than magnitude 5.5 in the distance range of 40º to 80º.
Objective: Aim: to determine the physical properties of the granitic basement in the soultz hdr borehole. General information: description: the core samples obtained from the granite section of the soultz gpk-1 borehole will be analysed to determine the properties of the granite such as strength and fracture toughness, thermal parameters, heat production (radiogenic content), and acoustic, electrical and magnetic properties. Achievements: The results of studies carried out on cores and cutting materials of three boreholes to a depth of 3.6 km are summarised. The physical property programme included measurements of density, ultrasonic velocities, seismic anisotropy, elasticity, fracture behaviour, electric and magnetic parameters, thermal properties including radioactive heat production, and radioactive age dating. Heat production in the Soultz granite is 2 to 3 times greater than that in other granites at the surface, although all surface granites in the vicinity show the same intrusion age. The physical property measurement programme has demonstrated that continuous measurements on cores and cuttings are essential for both operational drilling procedures and down hole condition assessment in crystalline rock formations. The European Geothermal Project involved teams from France and Germany who collaborated to test a site in the Upper Rhine Valley for its suitability for terrestrial heat mining (hot dry rock (HDR) energy production). Some British scientists participated in specific tasks. The site was chosen near Soulz-sous-Forets in Alsace at the location of the old oil field of Pechelbronn which was the first oil field exploited in Europe since the 18th century. It is situated on 1 of the summits of a very large thermic anomaly (200 km long and 20 km wide) where the mean geothermal gradient between the surface and 1500 m is known to be higher than 6.5 C/100 m. The programme began in July 1987 with a 2000 m deep borehole. Below at 1375 m thick sediment cover, the granitic basement was penetrated to a depth of 2000 m. The temperature at the bottom of the hole was 140 C. The geothermal gradient within the sediments was unusually high (10 C per 100 m) and diminished to a normal after a series of fractures inside the Buntsandstein producing some water at 116 C with a total salinity 98 g/l. At the depth of 1820 m, hydraulically active natural fissure was reached. The artesian outflow from this zone was 0.15 l/s, with well head pressure of 1.6 bars. The thermal water produced from the well had a high chloride contents and clearly had an identical origin with the fluid collected from the Buntsandstein just above the granite. During the water injection tests, a second active natural fissure was detected normally closed out but which seemed to aquire a noticeable permeability at a well head pressure of about 40 bars.