A new 3D geological model and interpretation of structural evolution of the world-class Rio Tinto VMS deposit, Iberian Pyrite Belt (Spain)

Abstract

A new 3D geological model and structural evolution of the Rio Tinto world-class VMS deposit is presented in this work. The Rio Tinto volcanogenic massive sulfide (VMS) deposit is located in the Spanish segment of the Iberian Pyrite Belt and is hosted by felsic porphyritic volcanic rocks and tuffs. Computer generated 3D modeling of the different orebodies and host rocks has been carried out using data from around 3,000 drill-core logs, allowing us to build 93 cross-sections and 6 plants (both 50 m spacing). This has enabled us to recognize of the geometry and relationships between the mineralization and the earliest Carboniferous transtensional tectonics through the development of an extensional pull-apart basin with two sub-basins separated by the NW-SE trending Eduardo Fault. The sub-basins, CerroColorado and San Dionisio, were limited by two E-W strike-slip faults, the Northern and Southern faults, and bounded in the east and west by the NW-SE-trending Nerva and Western faults, respectively. The generated pull-apart basin was first filled by a basaltic magmatism of mantle origin and later, following the deposition of the intermediate complex sedimentary unit, by rhyodacitic volcanic rocks of crustal origin. The evolution of the subsiding basins caused the development of an E-W oriented rollover anticline that affected these filling rocks.As a result of a counterclockwise rotation of the stress axes, the primitive pull-apart basin evolved into a basin affected by E-W transtensional sinistral shearing. Its northern and southern limits were favorable areas for increased hydrothermal fluid flow, which gave way A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT2 to the huge concentration of VMS mineralization located near the limits. The Northern and, to a lesser degree, the Southern extensional faults thus become channel areas for feeding and discharging of the VMS and stockwork ores. The main mineralizing period was related to this stage. Subsequently, during the Variscan transpressional phase, the E-W extensional faults were reactivated as inverse faults, affecting the volcanic sequence of mafic to felsic composition and the intermediate complex sedimentary unit. Fault propagation folds developed above these faults, affecting the massive sulfides, the transition series and the Culm flysch sediments, with buttressing playing a significant role in the geometry of tectonically inverted structures. The VMS mineralization and cupriferous stockworks were folded and dismembered from the original conduits in the volcanic series, and a dextral reactivation of the NW-SE trending faults also developed.Finally, it should be emphasized that this new 3D geological model is an approach to provide a better insight into the 3D structure of the world-class VMS Rio Tinto deposit and could be a key-point for further studies providing a new tool to increase knowledge of the VMS mineralizations and exploration guidelines elsewerein the IPB.

3D Modeling of the Epembe (Namibia) Nb-Ta-P-(LREE) Carbonatite Deposit: New Insights into Geometry Related to Rare Metal Enrichment

“…A geological database following the proposed workflows of Zanchi et al [20] and Martin-Izard et al [15] was created with the available datasets. The general modeling workflow is outlined in Figure 2.…”

“…The potential of 3D geological modeling is widely used in economic geology for resource estimations, to understand the processes of enrichment (e.g., [12][13][14][15]), and to provide more information on depth [16]. It is a powerful tool in structural geology for the visualization of complex fault systems, in particular if additional geophysical data are available (e.g., [17][18][19][20][21][22][23][24]).…”

Massive Sulfide Ores in the Iberian Pyrite Belt: Mineralogical and Textural Evolution

“…It is an area of significant geological and metallogenic interest because it represents the largest concentration of metallic sulfide deposits on Earth [10][11][12]. With more than 2000 Mt of massive sulfide ore, the IPB comprises an exceptional number of supergiant deposits, including the biggest in this class: Riotinto (>500 Mt) and Neves Corvo (≥300 Mt) [13,14].…”

“…The general characteristics of the IPB sulfide deposits, including their geological context, are well-documented in the literature [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. These studies mostly deal with geodynamic interpretations; [38]).…”

Application of Digital Techniques in Industrial Heritage Areas and Building Efficient Management Models: Some Case Studies in Spain

“…3D model of the Riotinto mining area[29]. This figure shows an axonometry, from the SE, of the open pit mines of Cerro Colorado and Corta Atalaya.…”