Petrography and geochemistry of fault-controlled hydrothermal dolomites in the Riópar area (Prebetic Zone, SE Spain)

Abstract

The present paper reports the first detailed petrographical and geochemical studies of hydrothermal dolomites related to MVT Zn-(Fe-Pb) deposits in the Riópar area (Mesozoic Prebetic Basin, SE Spain), constraining the nature, origin and evolution of dolomitizing and ore-forming fluids. Mapping and stratigraphic studies revealed two stratabound dolostone geobodies connected by other patchy bodies, which replace carbonate units of Upper Jurassic to Lower Cretaceous ages. These dolostones are associated to the WE trending San Jorge fault, indicating a main tectonic control for fluid flow. Seven different dolomite types were identified: i) matrix-replacive planar-s (ReD-I); ii) matrix-replacive planar-e (ReD-II); iii) planar-e sucrosic cement (SuD); iv) non-planar grey saddle dolomite cement (SaD-I) pre-dating Zn-(Fe-Pb) sulfides; v) nonplanar milky to pinkish saddle dolomite cement (SaD-II) postdating Zn-(Fe-Pb) ores; vi) ore-replacive planar-e porphyrotopic (PoD); and vii) planar-s cloudy cement (CeD). Meteoric calcite types were also recognized. The different dolomite types are 14 wt.% eq. NaCl), whereas the dolomitization related to ore precipitation (sphalerite and SaD-II) spreads to higher salinity values (5 to 25 wt.% eq. NaCl). These data may respond to a mixing between a low salinity fluid (fluid A, less than 5 wt.% eq. NaCl) and a more saline brine (fluid B, more than 25 wt.% eq. NaCl) at different fluid proportions.

Origin and evolution of mineralizing fluids and exploration of the Cerro Quema Au-Cu deposit (Azuero Peninsula, Panama) from a fluid inclusion and stable isotope perspective

“…The equipment was previously calibrated from the melting of synthetic H 2 O-CO 2 fluid inclusions (− 56.6°C), melting of ice and critical homogenization at 220 bar (374.1°C) of synthetic H 2 O inclusions in quartz. Reproducibility was ± 0.2°C below 0°C and ± 2°C at the fluid inclusion homogenization temperatures (e.g., Navarro-Ciurana et al, 2016). A total of 224 inclusions were measured (Th + Tmi) by cycling down to − 180°C and heating to the temperature of total homogenization to ensure stability of the inclusions and representativeness of the determinations.…”

Mineralogical and geochemical characterization of the Riópar non-sulfide Zn-(Fe-Pb) deposits (Prebetic Zone, SE Spain)

“…Three major types of Zn-Pb sulfide deposits are recognized in the Betic Cordillera (Fig. 1): i) Zn-(Fe-Pb) MVT deposits related to hydrothermal dolomites hosted in Lower Cretaceous carbonates of the Prebetic Zone (Navarro-Ciurana et al, 2015b;2016); ii) stratabound (F)-Zn-Pb-Fe MVT deposits hosted in hydrothermally dolomitized Triassic limestones of the Alpujárride Complex (e.g., Fenoll, 1987); and iii) Zn-Pb-Fe-(Ag) epithermal deposits hosted in Triassic carbonates and related to Late-Tertiary subvolcanic rocks (e.g., Oen et al, 1975).…”

Geochemical characteristics of Upper Jurassic – Lower Cretaceous platform carbonates in Hazine Mağara, Gümüşhane (northeast Turkey): implications for dolomitization and recrystallization

“…Such a large-scale dolomitization replacing Upper Jurassic-Lower Cretaceous limestones has been reported in throughout the mid-latitude shallow water domain D r a f t of Tethys and several models which accounts for the source of dolomitizing fluids and mechanism have been suggested to explain the origin of pervasive dolomitization (e.g. Murgia et al 2004, Iannace et al 2011Martín-Martín et al 2015;Navarro-Ciurana 2016).…”

“…A number of models have been proposed in order to understand the nature of paleofluid flow and its driving mechanisms of the formation of extensive dolomitization during shallow to deep burial conditions (Morrow 1998;Warren, 2000;Al-Aasm 2003;Congwei et al 2013). In recent years, massive dolomite bodies and their diagenetic alterations due to hydrothermal fluids have been increasingly documented because of their potential as hydrocarbon reservoirs and economic base-metals ore-deposits (e.g., Leach and Sangster 1993;Wendte et al 1998;Warren 2000;Muchez et al 2005;Davies and Smith 2006;Morrow 2014;Jiang et al 2016;Navarro-Ciurana 2016). However, many researchers proposed that it is very difficult to reveal the origin of dolomitization, because the massive dolomite bodies are generally affected by chemical alteration due to hydrothermal fluid flow which is affected by different tectonic event, magmatic generation and related polymetallic mineralizations during progressive burial history (e.g., Garven 1985;Muchez et al 2000;Martín-Martín 2015;Adam and Al-Aasm 2017;Navarro-Ciurana 2016).…”

“…In recent years, massive dolomite bodies and their diagenetic alterations due to hydrothermal fluids have been increasingly documented because of their potential as hydrocarbon reservoirs and economic base-metals ore-deposits (e.g., Leach and Sangster 1993;Wendte et al 1998;Warren 2000;Muchez et al 2005;Davies and Smith 2006;Morrow 2014;Jiang et al 2016;Navarro-Ciurana 2016). However, many researchers proposed that it is very difficult to reveal the origin of dolomitization, because the massive dolomite bodies are generally affected by chemical alteration due to hydrothermal fluid flow which is affected by different tectonic event, magmatic generation and related polymetallic mineralizations during progressive burial history (e.g., Garven 1985;Muchez et al 2000;Martín-Martín 2015;Adam and Al-Aasm 2017;Navarro-Ciurana 2016). Therefore, nowadays, besides traditional petrographic and geochemical analyses (e.g., Sr, Na, Fe, Mn, 13 C, 18 O, and 87 Sr/ 86 Sr), rare earth elements (REEs) of dolomite have been extensively applied to provide an important insights into tracing the origins of dolomitization and hydrothermal alterations in dolomites (e.g., Banner et al 1988;Qing and Mountjoy 1994;Wendte et al 1998;Azomani et al 2013).…”