This study presents the first U-Pb geochronological data on detrital zircon grains from the metas... more This study presents the first U-Pb geochronological data on detrital zircon grains from the metasedimentary successions of the Sierra Albarrana Domain (SW Iberian Massif) obtained by SHRIMP and LA-ICP-MS. We provide new information on the Maximum Depositional Ages (MDA) during the middle Cambrian through a systematic study, together with age comparisons of the successions, using Kernel Density Estimates (KDE) diagrams, Cumulative Age Distributions (CADs) and the Kolmogorov–Smirnov (K-S) test. On the other hand, the U-Pb zircon data presented in this study have been compared with all the existing data from detrital zircon grains in Neoproterozoic and Cambrian rocks of the Iberian Massif (20 samples, 2706 U–Pb zircon ages). For the comparison, in addition to the KDEs, CADs and K-S test, we apply 3D multidimensional scaling techniques (3D-MDS). The results, together with the geochemical and isotopic characterisation from previous studies, suggest that this domain is likely to be part of the autochthonous section of the Central Iberian Zone (CIZ). Zircon age patterns indicate a probable sedimentary provenance from the Saharan Metacraton with, or without, minor input from the Tuareg Shield. The most important local detrital source corresponds to Cadomian magmatism developed during a magmatic event (535–515 Ma) followed by back-arc extension and early Paleozoic rifting (535–460 Ma). The remaining Mesoproterozoic, Paleoproterozoic and Archean zircon grains would have been provided by the Paleoproterozoic basement and/or the older continental crust recycled in the western sections of the Gondwana margin
Abstract Iberia, Avalonia and the “Armorican” terranes form key constituents of the Variscan–Appa... more Abstract Iberia, Avalonia and the “Armorican” terranes form key constituents of the Variscan–Appalachian orogen, but their Neoproterozoic origins along the northern Gondwanan margin continue to be strongly debated. Here, we present a new detrital zircon U–Pb–Hf dataset from Neoproterozoic–Silurian sedimentary sequences in NW Iberia and Avalonia, in conjunction with the comprehensive existing datasets from potential source cratons, to demonstrate that the provenance of each terrane is relatively simple and can be traced back to three major cratons. The enigmatic Tonian–Stenian detrital zircons in autochthonous Iberian rocks were derived from the Saharan metacraton in the latest Neoproterozoic–early Cambrian. Avalonia is commonly considered to have been derived from the Amazonian margin of Gondwana, but the hafnium isotopic characteristics of the detrital zircon grains in early Neoproterozoic rocks bear much stronger similarities to Baltica. The hafnium isotopic array also suggests the early Avalonian oceanic arc was built on a sliver of “Grenvillian-type crust” (~ 2.0–1.0 Ga) possibly of Baltican affinity at ~ 800 Ma, prior to accretion with a continental margin at ~ 640 Ma. The Upper Allochthon of Iberia is frequently linked to the West African Craton in the late Neoproterozoic–early Cambrian, however the hafnium isotopic array presented here does not support this connection; rather it is more similar to the hafnium array from Avalonia. The Armorican terranes have strong detrital zircon isotopic links to the West African Craton during the late Neoproterozoic–Cambrian.
This study presents the first U-Pb geochronological data on detrital zircon grains from the metas... more This study presents the first U-Pb geochronological data on detrital zircon grains from the metasedimentary successions of the Sierra Albarrana Domain (SW Iberian Massif) obtained by SHRIMP and LA-ICP-MS. We provide new information on the Maximum Depositional Ages (MDA) during the middle Cambrian through a systematic study, together with age comparisons of the successions, using Kernel Density Estimates (KDE) diagrams, Cumulative Age Distributions (CADs) and the Kolmogorov–Smirnov (K-S) test. On the other hand, the U-Pb zircon data presented in this study have been compared with all the existing data from detrital zircon grains in Neoproterozoic and Cambrian rocks of the Iberian Massif (20 samples, 2706 U–Pb zircon ages). For the comparison, in addition to the KDEs, CADs and K-S test, we apply 3D multidimensional scaling techniques (3D-MDS). The results, together with the geochemical and isotopic characterisation from previous studies, suggest that this domain is likely to be part of the autochthonous section of the Central Iberian Zone (CIZ). Zircon age patterns indicate a probable sedimentary provenance from the Saharan Metacraton with, or without, minor input from the Tuareg Shield. The most important local detrital source corresponds to Cadomian magmatism developed during a magmatic event (535–515 Ma) followed by back-arc extension and early Paleozoic rifting (535–460 Ma). The remaining Mesoproterozoic, Paleoproterozoic and Archean zircon grains would have been provided by the Paleoproterozoic basement and/or the older continental crust recycled in the western sections of the Gondwana margin
Abstract Iberia, Avalonia and the “Armorican” terranes form key constituents of the Variscan–Appa... more Abstract Iberia, Avalonia and the “Armorican” terranes form key constituents of the Variscan–Appalachian orogen, but their Neoproterozoic origins along the northern Gondwanan margin continue to be strongly debated. Here, we present a new detrital zircon U–Pb–Hf dataset from Neoproterozoic–Silurian sedimentary sequences in NW Iberia and Avalonia, in conjunction with the comprehensive existing datasets from potential source cratons, to demonstrate that the provenance of each terrane is relatively simple and can be traced back to three major cratons. The enigmatic Tonian–Stenian detrital zircons in autochthonous Iberian rocks were derived from the Saharan metacraton in the latest Neoproterozoic–early Cambrian. Avalonia is commonly considered to have been derived from the Amazonian margin of Gondwana, but the hafnium isotopic characteristics of the detrital zircon grains in early Neoproterozoic rocks bear much stronger similarities to Baltica. The hafnium isotopic array also suggests the early Avalonian oceanic arc was built on a sliver of “Grenvillian-type crust” (~ 2.0–1.0 Ga) possibly of Baltican affinity at ~ 800 Ma, prior to accretion with a continental margin at ~ 640 Ma. The Upper Allochthon of Iberia is frequently linked to the West African Craton in the late Neoproterozoic–early Cambrian, however the hafnium isotopic array presented here does not support this connection; rather it is more similar to the hafnium array from Avalonia. The Armorican terranes have strong detrital zircon isotopic links to the West African Craton during the late Neoproterozoic–Cambrian.
El uso de fotogrametría para la reconstrucción 3D, de forma rápida y efi caz, de elementos del pa... more El uso de fotogrametría para la reconstrucción 3D, de forma rápida y efi caz, de elementos del patrimonio cultural se ha convertido en una herramienta de uso cotidiano en el mundo de la arqueología. La mejora en las técnicas de adquisición de datos y el uso de herramientas informáticas de última generación para el procesado de los mismos, permite la obtención de imágenes 3D de alta resolución. En este trabajo presentamos la documentación de dos zonas de interés arqueológico y arquitectónico muy dispares, mediante el uso de tecnología VANT, para la obtención de información tridimensional de la necrópolis neolítica de La Cabaña y el castillo de Úrbel, ambos situados en la provincia de Burgos y enmarcados dentro del Proyecto Geoparque de las Loras. En este trabajo analizamos los benefi cios y difi cultades que presenta el estudio de elementos del patrimonio, caracterizados por diferentes grados de conservación, geometría y dimensiones. La obtención rápida y precisa de modelos 3D mediante fotogrametría con drones de bajo coste facilita, además, la difusión al público general y promueve la protección del patrimonio, constituyendo una herramienta efi caz para la toma de datos con interés arqueológico.
RESUMEN La minería aurífera romana en el noroeste peninsular se concentra en cuatro gran-des dist... more RESUMEN La minería aurífera romana en el noroeste peninsular se concentra en cuatro gran-des distritos mineros: Las Médulas, Omañas, Duerna y Eria. La cuenca del Eria representa una de las mayores explotaciones auríferas —en extensión— de todo el Imperio Romano, sin embargo, es una de las que menos atención ha recibido hasta la fecha. Los trabajos arqueológicos realizados en la zona se basaban en el uso de fotografía aérea y en la prospección de campo para la elaboración de car-tografías de los sistemas hidráulicos y el análisis de los principales yacimientos. La incorporación de nuevas tecnologías, como el LiDAR aerotransportado y los vehículos aéreos no tripulados (drones o VANT), permite el estudio detallado y la adquisición de datos de elementos del paisaje arqueominero en zonas de difícil Arqueología en el valle del Duero: Del Paleolítico a la Edad Media. 5 ISBN: 978-84-946124-0-4, pp: 520-536
Northwest Spain possesses the largest Roman gold mining complex in Europe. The extent and scale o... more Northwest Spain possesses the largest Roman gold mining complex in Europe. The extent and scale of the mining works as well as the astonishing hydraulic infrastructure developed to supply water to the mining sectors caused a strong impact on the landscape. Within this scenario, the Teleno Mountains represents a natural laboratory to figure out the impact of the Roman mining anthropic activity both underground and superficial. However, the dense vegetation cover and the impact of more recent human activity in the area hinders most of the mining remains. To explore, re-evaluate and describe in detail the Roman elements, a detailed geomorphological survey is required. The location of geomorphic features on the landscape is particularly helpful in areas where neither archaeological, epigraphic nor literary sources are available. Thus, the use of geomatic methods such as airborne Light Detection and Ranging (LiDAR) and UAV-assisted photogrammetry provide high-resolution digital elevation models used for the identification, description and preservation of mining heritage remains. The image enhancement treatment of derived products is a rapid and cost-effective method for accurate mapping of the infrastructure remains with different degrees of preservation. The evaluation of the results suggests that large-scale and profound changes took place in the landscape, were linked to Roman mining, and provides a broad overview of the important human environmental impact in the light of the possible New Epoch, the Anthropocene.
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Papers by Gabriel Gutierrez-Alonso
protección del patrimonio, constituyendo una herramienta efi caz para la toma de datos con interés arqueológico.