Acidic Rocks Research Articles

Meta-bauxite deposit in the Tavşanlı Zone, NW Turkey: A new locality for gem-quality diaspore formation

The tectonic units of Sakarya Zone (Pontides) and Tavşanlı Zone (Anatolides) are exposed in the Mihalıççık area of central Anatolia. A Cretaceous accretionary complex that forms the İzmir-Ankara-Erzincan suture zone separates the units. Within this region, the Tavşanlı Zone is made up of a coherent series and tectonically overlying late Cretaceous mélange, which has undergone blueschist facies metamorphism. Coherent series consist of strongly retrogressed schists and conformably overlying platform-type thick marbles, known as the İnönü marbles.The İnönü marbles contain meta-bauxite lenses in the lower levels, which can be classified as karstic bauxites deposited in the karst holes within the original limestone. Considering the general stratigraphy of the Tavşanlı Zone, a middle Jurassic age can be envisaged for the bauxite formation. Geochemical data suggest that the bauxites were largely derived from redeposited argillic sediments, with minor and variable inputs from the weathering of intermediate to acidic rock. The mineral assemblage of the meta-bauxite consists of diaspore, chloritoid, muscovite, paragonite, Al-spinel (hercynite), magnetite, hematite and ilmenite. In addition, apatite, rutile, monazite, xenotime and zircon occur as accessory minerals. Limonite, goethite, akaganeite and kaolinite also formed during the latest stage of alteration. P-T conditions for the meta-bauxites are estimated as 20–27 kbar and 330–470 °C that are indicative of formation under high-P / low-T blueschist facies conditions.The meta-bauxites are cut by veins of diaspore, muscovite-paragonite, goethite, calcite and ankerite, and include gem-quality diaspore crystals up to 6 cm long. Textural evidence indicates that the diaspore formation is related to the extraction of aluminium from the meta-bauxite body and migration of Al-rich fluids into the shear zones during the last stage of the high-P metamorphism. During exhumation of the Tavşanlı Zone, these veins were brecciated by brittle deformation and the fractured minerals were cemented by granoblastic calcite and ankerite during the latest stage of the vein formation.

Rare Earth and Trace Elements Composition of a Residual Clay from Sosan Akoko, Southwestern Nigeria: Implications for Weathering and Provenance

The aim of this study is to determine the source area weathering and provenance of a residual clay samples overlying Precambrian basement complex in Southwestern, Nigeria. Fifteen representative clay samples were collected from three pits dug in three locations across the study area. The mineralogy and chemical composition of samples was analyzed using X-ray diffractometer (XRD) and inductively coupled plasma-mass spectrometer (ICPMS) techniques respectively. The results of mineralogical analyses indicates that kaolinite (1.4%) and nontronite (2.77%) are the major clay minerals present while the non-clay minerals include quartz, orthoclase, labradorite and albite. Chemical indices of alteration (CIA) and weathering (CIW) values of 76.02% and 89.9% respectively, low alkali and alkaline earth elements content derived from the samples implies a comparatively intense source area. Furthermore, plots of TiO2/Al2O3 indicate provenance of predominantly acidic rocks and high concentrations of Rubidium (Rb) and Strotium (Sr) in the samples with values ranging from 113.4-138.2 ppm and 218.3-229.2 ppm respectively suggests ongoing chemical weathering of the clay body. The findings from this research through mineralogical composition, rare earth elemental normalized patterns, and ternary diagrams plotted implies that these samples are derived from felsic sources.

Hydrogeochemistry characterization of an overexploited municipal, agricultural, and industrial aquifer, central Mexico

The Valley of Celaya aquifer, located in one of the most important agricultural and industrial areas in central Mexico, has been extremely overexploited for several decades for agricultural, industrial, and municipal uses. The Celaya aquifer is a multilayer, composed of an open upper alluvial (sedimentary deposit) aquifer with inter-layers of late tertiary acid tuffs and basalts (medium semi-confined aquifer) and a downward recharge from River La Laja. The groundwater follows a natural hydrogeochemical evolution, producing low total dissolved solids (TDS) carbonate-type to medium TDS Na-enriched carbonate-type water. The average water temperature is 33 °C, with three thermal groups (low temperature: 16–29 °C, medium temperature: 30–30 °C, and high temperature: 46–60 °C). The electrical conductivity ranges from 645 to 805 μS/cm. Isotopic data (δ2H and δ18O) indicates an evaporation and mixing line with a regression equation of δ2H = 5.48 xδ18O-20.67; R2 = 0.9827. Saturation index geothermometric calculations for the bottom of the well indicate temperatures ranging from 98 to 135 °C. The Cl vs. B relationships indicate the water chemistry is mostly due to local water-rock interaction with a minor magmatic contribution (deep igneous rock). The arsenic and fluoride concentrations are above the limits of the standard on the eastern part of the study area (As = 0.54 mg/L and F = 3.2 mg/L). The arsenic concentration may be due to groundwater residence time, while the fluoride concentration is generally associated with acid and intermediate volcanic rocks. Inverse geochemical modeling indicates a normal evolution of groundwater from meteoric water with some influence from meteoric water to rock-water interactions with sediments and volcanic rock to a deep regional aquifer. This aquifer is considered a low-temperature system (≤150 °C), conductive, and non-magmatic with extensional dominance where local faults produced by overexploitation play an important role in transporting water, and potentially toxic elements to the surface. The hydrogeochemical characterization in this study will help improve the sustainable management of groundwater resource.

Provenance of the Proterozoic Lesser Himalayan siliciclastics, northwest Himalaya, India: Implications to terrain accretion and crustal evolution

We present petrographical and geochemical data for the Lesser Himalayan sedimentary succession from the Tons Valley section of the Garhwal Lesser Himalaya. The succession consists of the least metamorphosed shale-dominant Chandpur Formation overlain by coarser-grained sandstones of Nagthat Formation. Petrographic studies of the Jaunsar Group siliciclastics reveal that apart from quartz 84 ± 9%, feldspar forms 5 ± 4% (with PF > KF) and rock fragments (micro- to mega-crystalline chert, orthoquartzite, gneisses, phyllites, and schists) constitute the remaining 11 ± 8%. The occurrence and existence of the labile components like feldspars, and rock fragments such as phyllites and schists, indicate less weathering and a relatively short distance of transport and provenance from a clastic wedge with a recycled nature of sediments. The major element discriminant function analysis indicates that the Nagthat Formation samples plot in the quartzose sedimentary-felsic igneous field and the Lower Chandpur Formation plots in the intermediate igneous provenance, supporting derivation from an Upper Continental Crust-like source. The TiO2 vs Ni diagram indicates acidic source rocks. Trace and REE combined discriminant diagrams support significant mafic input and confirm mafic and ultramafic rocks in the source area. In the Eu/Eu* vs GdN/YbN plot, lower values of Eu/Eu* suggest that the igneous/metamorphic provenance was affected by intra-crustal differentiation. The GdN/YbN > 2 value indicates a contribution from older sources like the Archean, whereas Phanerozoic granites have a ratio <2. It gives a clear indication that the detrital derivation for the Jaunsar Group is a product of a mixed source, consisting of a major portion of the thick sediments and meta-sediments of the Aravalli-Delhi Supergroup, along with the basement granite and granite gneiss from the Banded Gneissic Complex (BGC) and Bundelkhand Granite (BG). During the deposition of the Jaunsar Group of sediments, there was no substantial change in the provenance; however, as evidence indicates, it can be inferred that as time passed and the erosion deepened and widened, the primary sources such as BG and BGC were exposed more and more gradually. Sedimentation continued in the NW sector all through the ages of the Columbian until the gradual breakup of the Rodinia supercontinent.

Provenance of bauxite and clay deposits in the Carboniferous Benxi Formation, Western Henan, China: Constraints from U–Pb geochronology and regional geology

The bauxite and clay deposits of Western Henan, located in the southern part of the North China Craton (NCC), are rich reserves of bauxite ore, and the provenance of this bauxite has received much attention. In this study, X‐ray diffraction and detrital zircon U–Pb dating (using laser ablation–inductively coupled plasma–mass spectrometry) were applied to determine the source(s) of the bauxite in the Carboniferous Benxi Formation. Our data, combined with regional geological and geochemical observations, suggest that detrital zircons from the deposits with ages of ca. 457 Ma were derived mainly from Caledonian intermediate–acidic granitic rocks of the North Qinling Orogenic Belt (NQOB). Zircon grains with Precambrian ages of 2,713 to 549 Ma may have been derived from metamorphic rocks within the NQOB. The Benxi Formation bauxite in this area lacks late Palaeozoic zircons, which may be related to its location, as it is proximal to the NQOB but far from sources of late Palaeozoic zircons in the Inner Mongolia Uplift.

Geochemistry Characteristics and Paleoenvironmental Significance of Trace Elements in Coal and Coal Gangue in the Yangcheng Mining Area, Qinshui Basin.

The geochemical characteristics of trace elements in Carboniferous–Permian coal and gangue in the Yangcheng mining area in Qinshui Basin, a large Carboniferous–Permian coalfield in China, were studied by inductively coupled plasma mass spectrometry (ICP–MS), and their geological significance was discussed. The results show that the content of trace elements in late Paleozoic coal in the Yangcheng mining area is depleted, except for slight enrichment of Li. Except for Li, Co, and Mo, the content of trace elements in the gangue was higher than that in the coal. The content of rare earth elements in gangue (324.28 μg/g) is much higher than that in coal (66.22 μg/g). The rare earth elements (REY) content in the coal in the Shanxi Formation (93.88 μg/g) is slightly higher than that in the Taiyuan Formation (66.19 μg/g). The mean values of δEu and δCe are 0.71 and 0.94, respectively. Except for the YIC3-1 curve of the Shanxi Formation, which is obviously convex and shows a positive Eu anomaly, the REY distribution patterns of the remaining samples are similar, showing the characteristics of light rare earth elements (LREY) enrichment and heavy rare earth elements (HREY) depletion. The Carboniferous–Permian coal-forming environment in the Yangcheng mining area is in an anoxic-reducing, warm, humid, and brackish water sedimentary environment. The paleosalinity and paleotemperature of the Shanxi coal formation are higher than those of the Taiyuan Formation, which is more inclined to be a reducing environment. The provenance of Carboniferous–Permian coal in the Yangcheng mining area is mainly derived from acidic sedimentary rocks of the upper crust of the post-Archaean, mixed with a small amount of granite, alkaline basalt, and oceanic tholeiite. The tectonic setting of the provenance is mainly an active continental margin related to a continental island arc mixed with an oceanic island arc and a passive continental margin tectonic setting.

Geodynamic Formation Conditions and Age of Granitoids from Small Intrusions in the West of the Yana–Kolyma Gold Belt (Northeast Asia)

Abstract We report results of geological, mineralogical-petrographic, geochemical, isotope-geochemical (Sm–Nd, Rb–Sr), and geochronological (U–Pb, 40Ar/39Ar) studies of acid and intermediate intrusive rocks (granodiorites, leucocratic granites, subalkaline granites, and subalkaline leucocratic granites, diorites, and quartz diorites) of the Bukeschen and Samyr small plutons in the western part of the Yana–Kolyma gold belt (northeast Asia). These rocks are combined with Late Jurassic (151–145 Ma) dikes of basic, intermediate, and acid compositions into a single complex of small intrusions. They intrude the Upper Triassic–Middle Jurassic terrigenous deposits of continental margin blocks in the eastern part of the Verkhoyansk–Kolyma folded area. Our new U–Pb data for zircon (SHRIMP-II) indicate that the Bukeschen and Samyr pluton granitoids formed in the Berriasian, at 144.5 and 143 Ma, respectively. The small-intrusion granitoids have geochemical and isotope (Sm–Nd and Rb–Sr) characteristics similar to those of Late Jurassic dikes of varying composition. Therefore, they can be united into a single complex of small intrusions generated from a mixed source with the participation of mantle (OIB- and E-MORB type), lower crust, and subduction components and with Paleoproterozoic–Mesoproterozoic Sm–Nd model age estimates for the magma sources. Late Jurassic–Early Cretaceous magmatic and postmagmatic events and cooling of the intrusions played an important role in the processes of gold localization in the western part of the Yana–Kolyma gold belt. This is reflected in two tectonothermal stages (accounting for closing temperatures of the U–Pb, 40Ar/39Ar, and Re–Os isotope systems for different minerals) estimated at 151–141 and 138–137 Ma. These results for the small-intrusion complex agree with the tectonic model of the evolution of an active continental margin (northeastern Siberia) in the Mesozoic era, whose final development stage in the Berriasian age saw the formation of mostly small granitoid plutons.

Thermometry and determine the characterization of magma of Cretaceous acidic rocks using the zircon mineral morphology and compare it with whole-rock chemistry in SE Saqqez, NW Iran

Thermometry and determine the characterization of magma of Cretaceous acidic rocks using the zircon mineral morphology and compare it with whole-rock chemistry in SE Saqqez, NW Iran

Petrology and Detail Geological Mapping of the Precambrian Basement Rocks of the Sn-Ta-Nb Numbi Deposit, Democratic Republic of the Congo

The Numbi district of eastern Democratic Republic of the Congo (DRC) has high mineral interest; it has been exploited for decades by small scale artisanal miners for rare metals such as Sn, W, Ta and Nb. This area was investigated to elucidate the petrology of the basement rocks and to make their detailed geological map. From the petrographical and geochemical analyses, six lithological units were characterized. Granite and schist were the two main lithologies with some associated smaller rock units such as amphibolite, diorite, quartzite and pegmatite. Biotite is the common mineral found in all lithologies. The granite displays the mineralogical assemblages with the abundance of muscovite, biotite, feldspar, plagioclase and quartz. Diorite and amphibolite display less amount of quartz. Hornblende is very abundant in the amphibolite; less is the schist and a very small amount in the granite. Feldspar is mostly found in the granite, quite found in the quartzite and less in the schist rocks. In adding to these mineral assemblages, accessory and opaque minerals (iron oxide) are in a very small amount. Pegmatite is mostly found as altered veins. Schist, quartzite and granite samples share the fields of granodiorite while diorite and amphibolite samples share the fields of diorite and gabbroic diorite on the total alkali-silicate classification diagram and ranged under intermediate and acidic rocks. The area is abundantly rich in rare metals (pegmatite with Nb-Ta-Sn mineralization) and is fairly suitable for quarry activities.

Characterization of heavy metal migration, the microbial community, and potential bioremediating genera in a waste-rock pile field of the largest copper mine in Asia

Long-term metal(loid) pollution in waste rock piles is an underestimated environmental problem during ore production. To investigate the factors affecting the distribution of metal(loid)s, various physicochemical and microbial properties were analyzed in 70 soil and water samples taken from a waste rock pile field. The results were analyzed using different methods, such as interpolation and multivariate statistical analyses. The results showed that the distribution of metal(loid)s in the topsoil (0–20 cm) was characterized by large variations in Cu (38.33–5834.18 mg/kg), Cd (0.14–29.29 mg/kg), Cr (7.08–326.16 mg/kg), and As (3.68–91.06 mg/kg). The mean pH value of the soil in the waste rock pile field was 3.85, while it was 5.03 outside of the rock pile. The Shannon–Wiener diversity and Chao's richness indices decreased from 5.46 and 1855.62 outside of the rock pile to 3.95 and 817.82 inside the rock pile, respectively. Multivariate statistical analysis indicated that significant spatial heterogeneity in the soil properties led to differences in the metal(loid) fractions, and the residual fraction of different metal(loid)s varied from 20.69% to 99.98%. Acidification of the media and increasing the number of acidophilic bacteria mobilized Cu and Cr but did not affect As. Mobilization of Cu/Cr iron oxides and organic matter (OM) on As was detected in situ compared with previous studies. The results of this study can provide useful reference data for the remediation of metal(loid)–contaminated soil in acidic waste rock pile fields.

Metasomatism by Boron-Rich Fluids along Permian Low-Angle Normal Faults (Central Southern Alps, N Italy)

Low-Angle Normal Faults (LANFs) represent in the central Southern Alps area (N Italy) the main structures along which the Variscan basement is in contact with the Upper Carboniferous-Permian volcanic-sedimentary succession. Tourmalinites frequently occur along LANFs, usually replacing former cataclasites. The mineralogy and chemical composition of tourmalinites point to a metasomatic origin. LANFs, together with high-angle faults, controlled the opening of the Permian Orobic Basin and likely acted as a preferred pathway for hydrothermal fluids that triggered the Boron-metasomatism. Along the Aga-Vedello LANF, tourmalinites appear to have formed after the cessation of fault activity, as no brittle post-metasomatism deformation overprint has been observed. These relationships suggest that the circulation of B-rich fluids occurred after the opening of the Orobic Basin that is broadly constrained to the Early Permian. At the same time, ca. 285–270 Ma, a strong magmatic activity affected all the Southern Alps, ranging in composition from mafic to acidic rocks and from intrusions at deep crustal levels to effusive volcanic products. The Early Permian magmatism was likely the source of the late-stage hydrothermal fluids that formed the tourmalinites. The same fluids could also have played a significant role in the formation of the Uranium ore deposit of the Novazza-Vedello mining district, as the ore bodies in the Vedello valley are concentrated along the basement-cover contact.

3D structural control and spatial distribution of Zn-Pb-Cu grades in the Palmeirópolis VMS deposit, Brazil

ABSTRACT The Palmeirópolis Zn-Pb-Cu volcanogenic massive sulfide deposit consists of four areas, presenting distinct features regarding host rocks, the geometry of ore bodies, hydrothermal alteration, deformation intensity, and metal proportions. The seven modeled Zn-Pb-Cu ore bodies occur mainly along with the contact between the Mesoproterozoic acid and basic metavolcanics within amphibolite facies. Some characteristics such as the relation of higher Zn-Pb and Cu grades to a higher proportion of acid and basic metavolcanic host rocks respectively, the same metamorphic grade and the gradational contact between volcanic host rocks, and distribution of alteration halo suggest that the original stratigraphy is still preserved. A smooth folding superposing the initial tight folds that define the ore bodies indicates at least two deformation events after the Zn-Pb-Cu mineralisation in the Palmeirópolis deposit. Finally, the geometry of the 3D ore bodies in Palmeirópolis are discussed against other VMS deposits around the world with 3D data available in terms of age, metamorphic, and deformation grades.

Water- and frost-resistance of crushed stone mastic asphalt concrete prepared on sevilen-modified bitumen

Introduction. Currently, increasing the durability of road asphalt concrete pavements is one of the urgent issues, the solution of which provides a significant economic effect achieved by increasing the turnaround time, as well as the overall service life of highways. Asphalt concrete pavements with prolonged wetting due to weakening of structural bonds can be destroyed due to crumbling of mineral grains, which leads to increased wear of the pavement and the formation of potholes. Water penetrates into micro defects in the structure of asphalt concrete, leading to a decrease in the strength of the material. As a result, the corrosion resistance of asphalt concrete is reduced. To improve the quality of the binder and the durability of the asphalt concrete pavement, in particular from crushed stone-mastic asphalt concrete (SMA), various modifying additives, including polymer ones, are used. In this regard, a promising direction is the use of polymers containing active groups, which are able to provide an increase in adhesion to mineral materials, including those from acid rocks, and, consequently, water resistance. One of these is the ethylene vinyl acetate copolymer (EVAC).Materials and methods. In order to study the effect of sevilen on the water and frost resistance of asphalt concrete mixtures, crushed stone-mastic asphalt concrete mixtures were prepared based on bitumen modified with БНД 70/100 sevilen made in the Moscow Oil Refinery Plant was used as the initial bitumen in the preparation of modified binders. Tests of crushed stone-mastic asphalt concrete mixtures were carried out for the indicator of the content of air voids in accordance with GOST R 58406.8.2019, the coefficient of water resistance in accordance with GOST R 58401.18-2019 and frost resistance in accordance with GOST 12801-98.Results. It has been established that the content of air voids in asphalt concrete samples significantly decreases with an increase in the concentration of sevilene, which will further contribute to a higher frost resistance of the road surface. It is shown that the use of sevilen with 22% vinyl acetate makes it possible to increase the coefficient of water resistance of asphalt concrete mixtures due to the presence of polar molecules in the composition of ethylene vinyl acetate, actively interacting with the mineral components of the asphalt concrete mixture. The use of sevilen improves the frost resistance of asphalt concrete samples. So, the smallest decrease in strength in tests for frost resistance was shown by samples with 5% sevilene. It was found that polymer asphalt concrete based on binder with sevilene containing 22% vinyl acetate, which corresponds to the maximum basicity of the polymer, has the highest resistance to humidity and temperature effects of the environment.

Episodic continental extension in eastern Gondwana during the mid-late mesozoic: insights from geochronology and geochemistry of mafic rocks in the Tethyan Himalaya

ABSTRACT Mesozoic extension and rifting processes of the Gondwana continent are critical for understanding the opening and formation of the Indian Ocean. Here, we report petrological, geochemical, zircon U–Pb age, and Lu–Hf isotopic data of mafic dikes in the central Tethyan Himalaya to reveal the timing and mechanism of the eastern Gondwana rifting. These mafic rocks exhibit two groups in terms of TiO2 and MgO contents (Group I with TiO2 < 2.0 wt.%, whereas Group II with TiO2 > 2.0 wt.%), but (1) they have similar trace elements patterns and exhibit enriched Light Rare Earth Element (LREE) patterns without Eu anomalies and (2) they have a wide range of zircon εHf(t) values. Both the above geochemical characteristics are similar to those of the Oceanic Island Basalt (OIB). However, they also show typical features of continental crust input. Compared to Group II, Group I has higher MgO, Cr, and Ni abundances (more primitive) and more depleted Nb-Ta contents, which are similar to those of lower TiO2 Dala mafic rocks, suggesting that the continental crust signature was mainly inherited from the Greater India subcontinental lithospheric mantle (GI-SCLM). Therefore, the mafic rocks here were mainly derived from a hybrid source from both OIB-like enriched mantle and GI-SCLM. Furthermore, two groups of zircon U–Pb ages have been identified: the first group with a weight mean age of 139.9 ± 0.2 Ma, whereas the second group with a weight mean age of 163.2 ± 0.9 Ma. The Middle Jurassic zircons show similar characteristics to those of intermediate to acidic igneous rocks in the continental setting, and thus they might record a stage of magmatism associated with a tectonic extension event in the Indian passive continental margin. The Early Cretaceous ages represent the crystallization timing of the mafic dikes, which are coeval with most mafic rocks in the Tethyan Himalaya. Based on these observations and the literature data in the Tethyan Himalaya, we proposed that the Kerguelen plume was incubating underneath the Tethyan Himalaya at ca. 140 Ma, but it was not located in the triple junction among the Antarctic, Australian and Indian plates. Therefore, the Kerguelen plume might play a synergistic role in the break-up of eastern Gondwana, which had experienced at least two stages of tectonic extension during the Mid-Late Mesozoic.

Geochemical and hydrological evolution of mine impacted waters at the Argyle Diamond Mine, Western Australia

The lamproite ore body at the recently closed Argyle diamond mine is geochemically benign, but the surrounding sedimentary sequence contains two thin pyritic black shale beds that are prone to acidification. Although the waste rock is on average net neutralizing, some localized acidification and sulfate release was first observed in 1999 after 15 years of open pit mining. Contact and receiving water quality have been actively managed and monitored for 20 years to further limit the already low environmental risks posed by nitrate, nickel, magnesium and sulfate. All four solutes exhibited increasing concentrations across the monitoring network during or shortly after the period of peak waste rock production from 1999 to 2004. Since open pit mining and associated rock blasting ended in 2013, concentrations of nitrate have declined by 50%–90% at most locations. Nickel concentrations have also declined by 30% at the two acidic waste rock seeps which account for 80% of the dissolved nickel load. Sulfate and magnesium concentrations generally peaked between 2010 and 2013 and have not exhibited any significant increasing or decreasing trends since then. Annual offsite sulfate release since 2014 has averaged about 0.4% of the total sulfur inventory stored on site. Future sulfate concentrations and loads are predicted to gradually decline as the remaining sulfur inventory is depleted. Even during the 2005 to 2008 period, when all solute release rates were near their maximum, the receiving aquatic ecosystems remained intact with only subtle changes to some invertebrate communities. It is clear that peak release rates have already passed. The geochemical evolution at Argyle is much more rapid than at most other large mines. This is likely due to several factors including: 1. the low mean sulfur concentrations in the black shales; 2. the short geochemical lag time in the reactive units; 3. the high annual rainfall; and 4. a black shale segregation program that was initiated in roughly 1996.

Acid stimulation in carbonates: Microfluidics allows accurate measurement of acidic fluid reaction rates in carbonate rocks by quantifying the produced CO2 gas

Acid stimulation has been the interest of researchers for many years due to its high efficiency in improving the near-wellbore permeability caused by the formation damage. The productivity enhancement stems from the creation of extremely conductive pathways called wormholes as a result of the interaction between the acidic fluid and carbonate rocks. Therefore, it is crucial to quantify the reaction rate between the acidic fluid and the carbonate rocks to ensure achieving the desired outcome. In this study, we will utilize microfluidics technology to accurately calculate the reaction rate of hydrochloric acid (HCl) with carbonate rocks under flow conditions by quantifying the produced CO2 gas. This approach, unlike conventional methods, allows for accurate measurement, short experiment duration, reduction of chemical usage, and power consumption. In this study, the reaction rate of the HCl with Silurian dolomite was successfully measured by quantifying the produced CO2 gas over time and found to be a surface reaction limited regime. Additionally, the reaction rate of HCl and Indiana limestone was also measured for various HCl concentrations and found to be a mass transfer limit regime. The findings of this study allow for accurate reaction rate measurement of reactive fluid with carbonate rocks which will ultimately improve the design and prediction of carbonate acidizing process. Furthermore, the proposed method enables direct observation of the multi-physics process of porous media flow through a geo-material by facilitating the visualization and understanding of rock-fluid interactions. Lastly, the cell presented here offers a promising technique to investigate a real reservoir rock for fast and reliable laboratory tests. Multiple fluid-solid chemical reactions can be assessed, allowing direct observations of the flow and transport in porous and fractured media.

Evaluation of Pb isotope systematics and metal sources of the Biga Pb–Zn Province (NW Turkey) and comparison with the Pb isotope systematics of the Rhodope Massif

This study presents the Pb isotope values of the galenas and the wall rocks related to the Pb–Zn mineralizations in the Biga Peninsula which include two different continental crusts; Sakarya Zone and Rhodope Massif. Pb–Zn mineralizations in the Sakarya fragment in Biga Peninsula have higher 207Pb/204Pb (15.677–15.710, avg: 15.688) and 208Pb/204Pb (38.895–39.000, avg: 38.935) ratios compared to the Rhodope fragment in Biga Peninsula ratios (15.650–15.709, avg: 15.668 for 207Pb/204Pb, 38.771–38.947, avg: 38.814 for 208Pb/204Pb), though the 206Pb/204Pb ratios of both crusts (Sakarya fragment in Biga Peninsula: 18.749–18.782, avg: 18.763; Rhodope fragment in Biga Peninsula: 18.750–18.839, avg: 18.802) are similar. Also, both crusts have radiogenic 207Pb/204Pb ratios indicating an orogenic source of lead. The Pb isotope ratios of the wall rocks related to the mineralizations in the Sakarya fragment were plotted in close, though different areas on uranogenic and thorogenic diagrams. Only the areas of Oligo-Miocene plutonics and Miocene volcanics, considered to be the main sources of mineralization, coincide with each other. The Pb isotope ratios of galena samples from the Sakarya fragment overlap the Permo-Triassic metamorphic rock (Karakaya Complex) area and seem to be related to the Cenozoic magmatism, both in proximity and trend, in uranogenic-thorogenic diagrams. The intense calc-alkaline magmatism occurrence that followed the closure of the Neo-Tethys Ocean appears to have played an essential role in forming the Pb–Zn mineralizations of the Sakarya fragment by leaching lead from the wall rocks. This study has utilized the Pb isotope ratios of the wall rocks related to mineralizations in the Rhodope fragment from a previous study (one sample for each reservoir). With this data, the magmatic effect on the Pb–Zn mineralizations in the Rhodope fragment is shown to be more dominant compared to those of the Sakarya fragment. In addition, through this study, it was determined that the Pb isotope ratios of two different continental crusts (Sakarya and Rhodope fragments) which came together with the Intra-Pontide suture zone followed two different trends.The Pb isotope compositions of Pb–Zn deposits in Rhodope Massif (both in the fragments of the Balkans and Biga Peninsula) were also compared in this study. According to the Pb isotope ratios, crustal thickness, and amount of the acidic rocks, the crustal materials are dominant in the western part of the massif. These findings also indicate that the western part of the massif is typical for Pb–Zn deposits whereas the eastern part of the massif is typical for the Cu–Au deposits.

Towards the fertility trend: Unraveling the economic potential of igneous suites through whole-rock and zircon geochemistry (example from the Tapajós mineral Province, Northern Brazil)

Magmatic hydrothermal mineral deposits axiomatically frame the hosting pluton and the given tectonic setting in which they are inserted. Unsurprisingly, pre-Cambrian porphyry deposits are different than Phanerozoic examples, as collisional or post-collisional deposits are different than arc-related mineralizing systems. As such, this contribution assesses the tectonic framework and the magmatic evolution of the igneous suites present in south-central Amazonian Craton (Tapajós Mineral Province, TMP), and how these parameters translate into metallogenetic potential for the formation of magmatic-hydrothermal copper and gold deposits. For this purpose we gathered whole-rock geochemistry data from selected TMP copper and gold deposits and present new in situ trace-element and U-Pb analyses in zircon grains.The host rocks of the selected mineralizing systems belong either to the older magmatic sequence (OMS, 2.00–1.95 Ga), or to the younger magmatic sequence (YMS, 1.90–1.86 Ga). Whereas OMS presents characteristics of arc-related rocks, YMS represents the evolution towards post-orogenic or collisional setting. OMS might be divided into groups I, II and III granitoids. Group I comprises granites and granodiorites that mark the onset of the arc-magmatism in the TMP at ca. 2011 Ma. In this stage rocks are peraluminous, ferroan, anhydrous, show a strong crustal component and fO2 values close to or below the fayalite-magnetite-quartz buffer (ΔFMQ), yielding metallogenetic unfertile pluton. These rocks correlate with the Cuiú-Cuiú Complex and comprise samples from the Patrocínio and Tocantinzinho deposits. Group II granitoids correlate with the Creporizão Suite and comprise Tocantinzinho, São Jorge, Chapéu do Sol and Patrocínio deposit samples (with extrusive equivalents in the Coringa deposit). Rocks are metaluminous to peraluminous, magnesian to ferroan and mark the evolution of the magmatism towards more oxidizing (0 ≤ ΔFMQ ≤ + 4), hydrous and metallogenetically fertile conditions at ca. 1986 Ma. Mineralized zones are defined by gold bearing sulfide veins and veinlets within the potassic or sericitic alteration halos. Group III comprises rarer high-K, metaluminous, ferroan, anhydrous and reduced syenites and monzonites dated at 1993 and 1974 Ma, generated by decompression melting of metasomatized mantle. By itself, group III rocks should be considered as unfertile batches of magma, however, its interaction with the coeval, more hydrous and oxidized group II melts, confer these magmas their metallogenetic potential. Mineralization in group III rocks is defined by disseminated pyrrhotite – pyrite ± gold within the sericitic, chloritic and/or carbonate alteration zones.YMS comprises intermediate and acid rocks that belong to the Parauari Intrusive Suite and to the Iriri Group. Whereas, intermediate volcanics from YMS evolved on a hydrous and reduced petrologic trend, acid volcanics and the Batalha and Palito granitoids evolved on a dry and reduced trend, reflecting a change on TMP’s tectonic context, from magmatic-arc to a post-orogenic or collisional tectonic setting. Despite the reduced and anhydrous characteristic of the magmas, YMS’s metallogenetic potential is related with remobilization or melting of SCLM or lower crustal Au-rich sulfides formed on the previous magmatic events. Hence, the first pulses of the YMS might be considered as potentially fertile for the formation of Au-rich magmatic-hydrothermal deposits.

APATITE GEOCHEMISTRY IN ROCKS OF KORSUN-NOVOMYRHOROD ANORTOSITE-RAPAKIVI GRANITE PLUTON

Trace element concentrations (REEs, Y, Sr, Th, U) in apatites from the most typical rocks of the Korsun-Novomyrhorod anorthosite-rapakivi pluton (KNP) were measured. Apatite was the last liquidous phase to crystallize in all the studied rocks because of the low P2O5 content in the primary melts. In the basic rocks, apatite is the main source of REEs, especially LREEs, except for Eu and Y. In intermediate and acidic rocks, apatites have minor influence on REEs concentrations, but they are more enriched in Th and U. All chondrite-normalized REE patterns of apatite show large negative Eu-anomalies (Eu/Eu* 0.03-0.21). This anomaly as well as increased Sr contents is less prominent (0.39) only in apatite from the norite of the external part of the pluton. With increased magmatic differentiation, apatite becomes more enriched in REEs, but Sr is depleted in the basic and intermediate rocks. In addition, all apatites from these rocks are LREE enriched and depleted in HREE and Sc which is consistent with earlier clino- or orthopyroxene fractionation, considering the minor amounts of in REE in plagioclase. REE patterns normalized to the primitive mantle indicate LREE enrichment ((La/Lu)N = 10.8-36) of apatites from all types of rocks with pronounced negative anomalies of Sr and Eu. This is the result of their low compatibility with apatite compared to other REEs. Inasmuch as the distribution of Eu is related to oxygen fugacity, we think that such unusually low Eu-anomalies reflect the initial melt differentiation under abyssal conditions. Thus, ubiquitous strong negative Eu-anomalies in apatites of all types of rocks are a result of two factors occurring during parent melt fractionation, namely early intensive plagioclase fractionation and highly reduced conditions during melt differentiation. By similar trace elements concentration and similarity of REE distribution in apatites it is probably that basic rocks and monzonitesare are derived from the same primary melt. At the same time, apatites from granites and syenites show maximum enrichment of REEs, especially HREE and Y. This indicates crystallization from residual differentiated melts (for syenites) or partial interaction of melts of various composition (basic and acidic) with migration of enriched LILE and REE solutions into acidic melts. The low content of P2O5 in ore-bearing rocks and ores of KNP, as well as the absence of Ti-magnetite and high iron enrichment of mafgic minerals and the unusually strong and negative Eu-anomalies in apatites, clearly distinguishes them from the Fe-Ti-P ores of the Korosten pluton. This suggests differences in the chemical composition of primary melts as well as the physical conditions of their differentiation.

Petrology, geochemistry, and geodynamic implications of the Ediacaran volcanism of the southwestern edge of the Saghro massif (Eastern Anti-Atlas, Morocco)

The southwestern edge of the Saghro Massif experienced during the Ediacaran period an intense volcanic activity represented by basaltic andesites and acid rocks with ignimbritic dominance. The chemical characteristics of these rocks correspond to those of calc-alkaline orogenic magmatism related to a subduction zone. The genesis of these two rock groups does not seem to be controlled by the fractional crystallization process as a factor controlling their evolution. Partial melting of a lithospheric mantle still influenced by the Pan-African orogeny and a contaminated constituent of the lower continental crust is a likely source of the basaltic andesites. Ignimbrites represent the product of the anatexic melting of sialic material in contact with basic magmas. Despite the calc-alkaline and orogenic character, the genesis of the studied rocks would be linked to a Pan-African distensive postcollisional tectonic context.