BUSCADOR RECOLECTA

IBERSEIS is a 303 km long deep seismic reflection profile. The transect was recorded in 56 days (from May to July 2001) using a 400 channel SERCEL 388 and five 22 Ton Vibroseis trucks. The asymmetric split spread configuration changed along the profile according to the dips of outcropping structures. To achieve a high resolution at shallow levels and to image steep dips, a 35 m station spacing and a 70 m Vibration Point interval was used with a high fold (60 in average). A relatively long sweep (20 s) was chosen to increase the source energy rather than increasing the number of sweeps per Vibration Point. The migrated and stack dataset derived from this raw data are available in http://hdl.handle.net/10261/220989, IBERSEIS NI: Migrated and stack files: http://dx.doi.org/10.20350/digitalCSIC/12643 ; http://hdl.handle.net/10261/220989, IBERSEIS Normal Incidence (IBERSEIS-NI) is a NE-SW oriented deep seismic reflection profile that provided for the first time a complete section at crustal scale of the Variscan Iberian Massif in the SW of Spain. This seismic profile samples three major tectonic terranes: the South Portuguese Zone, the Ossa-Morena Zone, and the Central Iberian Zone. These terranes show a distinctive seismic signature, as do the sutures separating them. Late strike-slip movements through crustal wedges are apparent in the seismic image and have strongly modified the geometry of sutures. The upper crust appears to be decoupled from the lower crust all along the seismic line, but some deformation has been accommodated at deeper levels. A sill-like structure is imaged in the middle crust as a 1–2 s thick and 175 km long high-amplitude conspicuous reflective band. It is interpreted as a great intrusion of mafic magma in a mid-crustal decollement. Taking into account surface geological data and the revealed crustal architecture, a tectonic evolution is proposed for SW Iberia which includes transpressional collision interacting during Early Carboniferous with a mantle plume. The Moho can be identified along the entire transect as subhorizontal and located at 10 to 11 s, indicating a 30–35 km average crustal thickness. Its seismic signature changes laterally, being very reflective beneath the South Portuguese Zone and the Central Iberian Zone, but discontinuous and diffuse below the Ossa Morena Zone., Comisión Interministerial de Ciencia y Tecnología-Fondo Europeo de Desarrollo Regional (CICYT-FEDER), 1FD1997-2179/RYEN1.-- Junta de Andalucía.-- ENRESA.-- Swedish Research Council.-- Instituto Geológico y Minero de España.-- Spanish Ministry of Science and Technology, BTE2000-0583-C02-01, BTE2000-3035-E, BTE2000-1490-C02-01, Peer reviewed

The wide-angle seismic reflection data set consists of two transects. Transect A coincides with the trace of the IBERSEIS deep seismic reflection profile and transect B is located farther to the SE. The explosive charge was located in a single 20 cm diameter, 50–60-m deep shothole. Explosive shots with charge sizes of 1000, 750 and 500 kg, where distributed along the transect, with the largest charges located at the edges of the profile. 650 digital seismic recorders (590 Texans and 60 3-component Refteks) from IRIS (Incorporated Research Institutions for Seismology) instrument pool where used. These instruments where placed along the 300-km transect A at a 400-m station spacing. For transect B, a denser trace spacing was used. To achieve this, shots were fired twice. The stations were firstly placed at 300–400 m spacing along transect B. Once the shots were fired, the stations were moved 150–200 m toward the north along the profile. All shots were then fired a second time, resulting in shot records with a 150–200 m trace spacing., The IBERSEIS wide-angle seismic reflection dataset consists of two NE-SW oriented transects acquired in the SW of the Iberian Massif. They crossed three major geological zones (South Portuguese Zone, Ossa-Morena Zone, and Central Iberian Zone), with their tectonic contacts and the Pyrite Belt being of greatest interest. The velocity models obtained by forward modeling show a complex crust, especially in the middle crust. The velocity models are the most detailed ones that have been produced in the area and contain a large amount of new features that are relevant to the understanding of the composition of the crust and upper mantle beneath the zone., Spanish Ministry of Science and Innovation, CGL2004-04623, CSD2006-00041.-- Generalitat de Catalunya.-- Junta de Andalucía.--, Peer reviewed

The ALCUDIA transect is a 230 km long, vertical incidence deep seismic reflection profile acquired in 2007. The acquisition parameters, 35 m station spacing, 70 m Vibration Point spacing resulted in a 60-90 fold high resolution seismic reflection image. A 20 s long Vibroseis sweep with frequencies between 8-80 Hz was recorded by a 400 station recording cable and 14 km long split spread configuration., ALCUDIA Normal Incidence (ALCUDIA-NI) is a NE-SW oriented vertical incidence deep seismic reflection transect in the SW of Spain that aimed to image the Variscan Iberian Massif. This transect sampled the Central Iberian Zone and was designed to be the northward continuation of the IBERSEIS-NI seismic profile. The processed image shows a weakly reflective upper crust, a thick, highly reflective and laminated lower crust, and a flat Moho located at 10 s TWTT (30 km depth). The transect can be divided into three segments with different structural styles in the lower crust. In the central segment, the lower crust is imaged by regular, horizontal and parallel reflectors, whereas in the northern and southern segments it displays oblique reflectors interpreted as an important thrust (north) and tectonic wedging involving the mantle (south). The ALCUDIA-NI shows that in an intracontinental orogenic crust, far from the suture zones, the upper and lower crust may react differently to shortening in different sectors, which is taken as evidence for decoupling. The interpreted structures, as deduced from surface geology and the seismic image, show that deformation was distributed homogeneously in the upper crust, whereas it was concentrated in wedge/thrust structures at specific sectors in the lower crust., Spanish Ministry of Science and Innovation, CGL2004-04623/BTE, CSD2006-00041.-- Ministerio de economía y competitividad, CGL2007-63101/BTE.-- Ministerio de economía y competitividad; Fondos Europeos de desarrollo regional (FEDER), CGL2011-24101.-- Junta de Castilla-La Mancha.--, Peer reviewed

The acquisition design included three lines of receivers, having a total length of ca. 350 km. The main line, ALCUDIA-WA, is ca. 310 km long strikes NE-SW to NNE-SSW, it is approximately perpendicular to the structural grain. A 40 km long line of receivers that trends NNW-SSE was deployed perpendicular to the Central System (CS) mountain range. Over 900 TEXANS (single component, digital recording seismic station) from the IRIS-PASSCAL Instrument Pool were deployed from the northern boundary of the Ossa-Morena Zone to the alpine thrust representing the southern boundary of the CS. The entire ALCUDIA-WA survey had a nominal shot and receiver spacing of 70 km and 400m, respectively. Five explosive sources, each one consisting in 1 TM of explosive, were placed in ~55m deep single boreholes, providing a signal rich in high frequencies resulting in shot records characterized by high signal-to-noise ratio. For this reason, these data can be qualified as a high-resolution wide-angle data set., The high-resolution, wide-angle seismic reflection experiment, ALCUDIA-WA, was acquired in 2012 across central Iberia, aiming to constrain the lithospheric structure and resolve the physical properties of the crust and upper mantle. The seismic transect, ca. 310 km long, crossed the Central Iberian Zone from its suture with the Ossa Morena Zone to the southern limit of the Central System mountain range., Spanish Ministry of Science and Innovation, CGL2004-04623/BTE, CGL2007-63101/BTE, CGL2011-24101, CSD2006-00041.--, Peer reviewed

Two onshore profiles were acquired in E-W and N-S directions through the Variscan and Alpine domains of 140 and 65 km length, ESCI-N1 and ESCI-N2 respectively. Also two offshore profiles ESCI-N3 and ESCI-N4 were obtained with a streamer of 4500 m having 360 channels with a 12.5 m gap between them and a 40 l airgun capacity. ESCI-N3 follows a swerved line in a mainly E-W direction crossing the Variscan structures. ESCI-N4 is a N-S direction profile that crosses both the Cantabrian margin and Le Danois bank Alpine structures. Techincal specifications of offshore profiles: streamer length 4,500 m, 360 channels, group interval 12,5 m and sample rate 4 ms., The ESCI-N project in Northwestern Spain was a subprogram of the ESCI Program (Estudios Sísmicos de la Corteza Ibérica). It is formed by four seismic experiments both on and offshore. This project aimed to image the Cantabrian Zone, West Asturian-Leonese Zone and the northern Iberian margin, thus characterizing the crustal structure resulted from the Variscan and Alpine orogenies and the Mesozoic extension related to the opening of the Bay of Biscay., CICYT (Committee of Science and Technology of the Spanish Ministry of Education and Science), GEO90-0660.-- FICYT (Fundación para el Fomento en Asturias de la Investigación Científica Aplicada y la Tecnología).-- Science and Technology for Regional Innovation and Development in Europe-European Commission, Peer reviewed

The study area covers an area of 36 km2 and included approximately 5000 mixed (Vibroseis and explosives) source points recorded with a 25 m inline source and receiver spacing., The Basque–Cantabrian Basin of the northern Iberia Peninsula constitutes a unique example of a major deformation system, featuring a dome structure developed by extensional tectonics followed by compressional reactivation. The occurrence of natural resources in the area and the possibility of establishing a geological storage site for carbon dioxide motivated the acquisition of a 3-D seismic reflection survey in 2010, centered on the Jurassic Hontomín dome. The objectives of this survey were to obtain a geological model of the overall structure and to establish a baseline model for a possible geological CO2 storage site., Spanish Ministry of Industry, Tourism and Trade through the CIUDEN and ICTJA agreement.--European Union through the Technology Demonstration Plant of Compostilla.--Spanish Ministry of Education Science.--Generalitat de Catalunya.--, Peer reviewed