Next Article in Journal
Pb2+ Uptake by Magnesite: The Competition between Thermodynamic Driving Force and Reaction Kinetics
Next Article in Special Issue
Erratum: Crespo et al. Ore Mineralogy, Trace Element Geochemistry and Geochronological Constraints at the Mollehuaca and San Juan de Chorunga Au-Ag Vein Deposits in the Nazca-Ocoña Metallogenic Belt, Arequipa, Peru. Minerals 2020, 10, 1112
Previous Article in Journal
Laboratory Study on the Effectiveness of Limestone and Cementitious Industrial Products for Acid Mine Drainage Remediation
Previous Article in Special Issue
Evolution of Pyrite Compositions at the Sizhuang Gold Deposit, Jiaodong Peninsula, Eastern China: Implications for the Genesis of Jiaodong-Type Orogenic Gold Mineralization
Article

Gold in the Farallones Block of the Shale-Hosted, Clastic-Dominated Castellanos Zinc-Lead Deposit (Northwest Cuba)

1
Department of Geology, Universidad de Pinar del Río Hermanos Saiz Montes de Oca, Pinar del Rio 20100, Cuba
2
Department of Mineralogy and Petrology, Instituto Andaluz de Ciencias de la Tierra (UGR-CSIC), Faculty of Sciences, Universidad de Granada, 18071 Granada, Spain
3
Department of Mineralogy and Petrology, Faculty of Geological Sciences, Universidad Complutense de Madrid, 28040 Madrid, Spain
4
Department of Geodynamics, Faculty of Sciences, Universidad de Granada, 18071 Granada, Spain
*
Author to whom correspondence should be addressed.
Academic Editors: Tamer Abu-Alam and Basem Zoheir
Minerals 2021, 11(4), 414; https://doi.org/10.3390/min11040414
Received: 9 February 2021 / Revised: 3 April 2021 / Accepted: 12 April 2021 / Published: 14 April 2021
The Zn-Pb ores of the Castellanos shale-hosted, clastic-dominated deposit in northwest Cuba average nearly 1 g/t Au, with local maximum concentrations up to 34 g/t Au. This deposit is stratiform with respect to the bedding in the host black shales and shows a bottom to top zoning of ore assemblages made up of a stockwork underlying the main orebody, a basal pyrite-rich zone and a disseminated to massive Zn-Pb ore zone capped by a discontinuous, thin barite-rich zone. Petrographic data and textural relations allow distinguishing five textural types of pyrite (framboidal Py I, colloform Py IIa, euhedral Py IIb, massive Py IIc and banded colloform Py III) successively formed during ore deposition. The main Zn-Pb ore formed after the crystallization of disseminated, sedimentary framboidal pyrite (Py I) in black shales by the superimposition of several crystallization events. The crystallization sequence of the main ore-forming stage evolved from the precipitation of colloform sphalerite and pyrite (Py IIa) with skeletal galena and interstitial dolomite-ankerite to similar ore assemblages but showing subhedral to euhedral crystal habits (Py IIb) and interstitial calcite-rich carbonates. This stage ended with the development of massive pyrite (Py IIc), mainly occurring at the base of the stratiform orebody. A late fracturing stage gave way to the development of a new generation of colloform banded pyrite (Py III) just preceding the crystallization of early barite. Au is mainly concentrated in pyrite showing variable contents in the different textural types of pyrite and a bottom to top enrichment trend. Minimum contents occur in massive pyrite (Py IIc) from the basal pyrite-rich zone (0.18 ppm Au average), increasing in pyrite IIa (from 0.29 to 2.86 ppm Au average) and in euhedral pyrite (Py IIb) (from 0.82 to 9.02 ppm Au average), reaching maxima in colloform banded pyrite (Py III) formed just before the crystallization of early barite at the top of the orebody. Au enrichment in pyrite correlates with that of Sb (0.08–4420 ppm), As (0.7–35,000 ppm), Ag (0.03–1560 ppm) and to a lesser extent Cu (3–25,000 ppm), Ni (0.02–1600 ppm) and Mn (0.6–5030 ppm). Au deposition should have taken place by oxidation and, probably cooling, of reduced (H2S-dominated) fluids buffered by organic matter-rich black shales of the host sedimentary sequence. The input of such reduced fluids in the ore-forming environment most probably occurred alternating with that of the main oxidized fluids which leached Zn and Pb from the large volume of sandstones and siltstones making up the enclosing sequence, thus being responsible for the precipitation of the majority Zn-Pb ore. Supply of Au-carrying reduced fluids might progressively increase over the course of ore formation, reaching a maximum at the beginning of the late fracturing stage. This evolution of Au supply is consistent with the early crystallization of barite since Ba can also only be transported at low temperature by highly reduced fluids. These results highlight the potential of medium-sized, shale-hosted, clastic-dominated deposits to contain economic (by product) Au amounts and show that ore-forming fluids can change from oxidized (SO42+ dominated) to reduced (H2S-dominated), and vice versa, throughout the evolutionary history of a single deposit. View Full-Text
Keywords: gold; shale-hosted deposits; clastic-dominated deposits; zinc-lead ores; arsenian pyrite; Castellanos deposit; Cuba gold; shale-hosted deposits; clastic-dominated deposits; zinc-lead ores; arsenian pyrite; Castellanos deposit; Cuba
Show Figures

Figure 1

MDPI and ACS Style

Gómez-Vivo, D.; Gervilla, F.; Piña, R.; Hernández-Díaz, R.; Azor, A. Gold in the Farallones Block of the Shale-Hosted, Clastic-Dominated Castellanos Zinc-Lead Deposit (Northwest Cuba). Minerals 2021, 11, 414. https://doi.org/10.3390/min11040414

AMA Style

Gómez-Vivo D, Gervilla F, Piña R, Hernández-Díaz R, Azor A. Gold in the Farallones Block of the Shale-Hosted, Clastic-Dominated Castellanos Zinc-Lead Deposit (Northwest Cuba). Minerals. 2021; 11(4):414. https://doi.org/10.3390/min11040414

Chicago/Turabian Style

Gómez-Vivo, David, Fernando Gervilla, Rubén Piña, Rebeca Hernández-Díaz, and Antonio Azor. 2021. "Gold in the Farallones Block of the Shale-Hosted, Clastic-Dominated Castellanos Zinc-Lead Deposit (Northwest Cuba)" Minerals 11, no. 4: 414. https://doi.org/10.3390/min11040414

Find Other Styles
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop