scholarly journals Geochemical and stable isotopic data on barren and mineralized drill core in the Devonian Popovich Formation, Screamer sector of the Betze-Post gold deposit, northern Carlin trend, Nevada

2011 ◽  
Author(s):  
William D. Christiansen ◽  
Albert H. Hofstra ◽  
Pamela B. Zohar ◽  
Gilles Tousignant
Keyword(s):  
Gold Deposit ◽  
Drill Core ◽  
Isotopic Data ◽  
Stable Isotopic ◽  
Carlin Trend

Microthermometric and stable isotopic (O and H) characteristics of fluid inclusions in the porphyry related Çöpler (İliç - Erzincan) gold deposit, central eastern Turkey

2014 ◽  
Vol 6 (2) ◽  
Author(s):  
Oktay Canbaz ◽  
Ahmet Gökce
Keyword(s):  
Gold Deposit ◽  
Fluid Inclusions ◽  
Native Gold ◽  
Homogenization Temperature ◽  
Early Mesozoic ◽  
Wide Range ◽  
Stable Isotopic ◽  
Water Field ◽  
Two Phases ◽  
Opaque Minerals

AbstractThe Çöpler gold deposit occurs within the stockwork of quartz hosted by the Çöpler granitoid (Eosen) and by surrounding metasediments of Keban metamorphic (Late Paleozoic - Early Mesozoic) and the Munzur limestones (Late Carboniferous - Early Cretaceous).Native gold accompanied by small amounts of chalcopyrite, pyrite, magnetite, maghemite, hematite, fahlerz, marcasite, bornite, galena, sphalerite, specular hematite, goethite, lepidochrosite and bravoitic pyrite within the stockwork ore veinlets. In addition, epidote (pistazite - zoisite), garnet, scapolite, chlorite, tremolite/actinolite, muscovite and opaque minerals were determined within the veinlets occurred in skarn zones.The study of fluid inclusions in quartz veinlets showed that the hydrothermal fluids contain CaCl2, MgCl2 and NaCl and the salinities of the two phases (L+V) inclusions range from 1.7 to 20.6% NaCl equivalent. Salinity values up to 44% were determined within the halite bearing three phases inclusions. Their homogenization temperature values have a wide range from 145.0 to 380.0°C, indicative of catathermal/hypothermal to epithermal conditions. The δ 18O and δD values of the fluid inclusion waters from the Çöpler granitoid correspond to those assigned to Primary Magmatic Water, those from the metasediments of Keban metamorphics fall outside of the Primary Magmatic and are within the Metamorphic Water field. A sample from a quartz vein within the skarn zone hosted by the Munzur limestones has a particularly low δD value.The results suggest that fluids derived from the granitoids were mixed with those derived from the metasediments of Keban metamorphics and the the Munzur limestones and resulting in quartz veinlets in these lithologies and the formation of stockwork ores. In view of the occurrence, the features described and processes envisaged for this study area may be applicable in similar settings.

scholarly journals Dynamic Metasomatism: Stable Isotopes, Fluid Evolution, and Deformation of Albitite and Scapolite Metagabbro (Bamble Lithotectonic Domain, South Norway)

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-22 ◽  
Author(s):  
Ane K. Engvik ◽  
Heinrich Taubald ◽  
Arne Solli ◽  
Tor Grenne ◽  
Håkon Austrheim
Keyword(s):  
Stable Isotopes ◽  
Chemical Evolution ◽  
Metal Transport ◽  
Ductile Deformation ◽  
Crustal Evolution ◽  
Fluid Type ◽  
Isotopic Data ◽  
Magmatic Rocks ◽  
Stable Isotopic ◽  
Magmatic Fluids

New stable isotopic data from mineral separates of albite, scapolite, amphibole, quartz, and calcite of metasomatic rocks (Bamble lithotectonic domain) give increased knowledge on fluid type, source, and evolution during metamorphism. Albite from a variety of albitites givesδ18OSMOWvalues of 5.1–11.1‰, while quartz from clinopyroxene-bearing albitite gives 11.5–11.6‰.δ18OSMOWvalues for calcite samples varies between 3.4 and 12.4‰and shows more consistentδ13C values of −4.6 to-6.0‰. Amphibole from scapolite metagabbro yields aδ18OSMOWvalue of 4.3 to 6.7‰andδDSMOWvalue of −84 to −50‰, while the scapolite givesδ18OSMOWvalues in the range of 7.4 to10.6‰. These results support the interpretation that the original magmatic rocks were metasomatised by seawater solutions with a possible involvement from magmatic fluids. Scapolitisation and albitisation led to contrasting chemical evolution with respect to elements like P, Ti, V, Fe, and halogens. The halogens deposited as Cl-scapolite were dissolved by albitisation fluid and reused as a ligand for metal transport. Many of the metal deposits in the Bamble lithotectonic domain, including Fe-ores, rutile, and apatite deposits formed during metasomatism. Brittle to ductile deformation concurrent with metasomatic infiltration illustrates the dynamics and importance of metasomatic processes during crustal evolution.

Paleoceanographic modeling of temperature-salinity profiles from stable isotopic data

1989 ◽  
Vol 4 (5) ◽  
pp. 585-591 ◽  
Author(s):  
L. Bruce Railsback ◽  
Thomas F. Anderson ◽  
Spafford C. Ackerly ◽  
John L. Cisne
Keyword(s):  
Isotopic Data ◽  
Stable Isotopic

scholarly journals African hominin stable isotopic data do not necessarily indicate grass consumption

2013 ◽  
Vol 110 (43) ◽  
pp. E4055-E4055 ◽  
Author(s):  
M. Fontes-Villalba ◽  
P. Carrera-Bastos ◽  
L. Cordain
Keyword(s):  
Isotopic Data ◽  
Stable Isotopic

Paleomagnetic and isotopic evidence for the diagenesis and alteration of evaporites in the Paleozoic Elk Point Basin, Saskatchewan, Canada

1997 ◽  
Vol 34 (12) ◽  
pp. 1619-1629 ◽  
Author(s):  
G. Koehler ◽  
T. K. Kyser ◽  
R. Enkin ◽  
E. Irving
Keyword(s):  
Low Temperature ◽  
Grain Boundaries ◽  
Fluid Inclusions ◽  
Low Temperatures ◽  
Late Paleozoic ◽  
Isotopic Data ◽  
Fine Grained ◽  
Tectonic Events ◽  
Stable Isotopic ◽  
Reversed Polarity

In the Paleozoic Elk Point Basin, Saskatchewan, Canada, hematite in evaporite rocks of the Middle Devonian Prairie Formation records two magnetizations that are very different from those expected when the evaporites were originally deposited. The first (X magnetization) corresponds to Cretaceous or Cenozoic paleofield directions and contains both normal and reversed polarities. The second (Y magnetization) appears to be a composite of Cretaceous–Cenozoic and late Paleozoic (Kiaman) reversed polarity directions. The X magnetization occurs in anomalous ores and is associated with fine-grained hematite occurring predominantly along grain boundaries. The Y magnetization occurs in normal ore and is associated with sylvite that has hematite both along grain boundaries and within sylvite crystals, the latter inferred to be of Kiaman age. K–Ar ages of the host sylvites are also composite, and are consistent with those inferred from paleomagnetic directions. Stable isotopic compositions of fluid inclusions in halite and the associated hematite in the Prairie Formation indicate that the hematite carrying the X magnetization formed at low temperature (about 60 °C) by fluids similar to those currently resident in overlying formations. The hematite carrying the inferred late Paleozoic magnetization was also formed at low temperatures by fluids having δD and δ18O values significantly lower than Paleozoic seawater. Paleomagnetic, petrographic, and isotopic data, and K–Ar ages indicate that evaporites in the Elk Point Basin have been affected by major fluid events that occurred during the late Paleozoic and Cretaceous–Cenozoic. These fluids are most probably related to brines mat have their origins within the basin, which were mobilized by major tectonic events.

Precipitation Source Inferred from Stable Isotopic Composition of Pleistocene Groundwater and Carbonate Deposits in the Western Desert of Egypt

1997 ◽  
Vol 48 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Mohamed Sultan ◽  
Neil Sturchio ◽  
Fekri A. Hassan ◽  
Mohamed Abdel Rahman Hamdan ◽  
Abdel Moneim Mahmood ◽  
...  
Keyword(s):  
Water Vapor ◽  
North Africa ◽  
Western Desert ◽  
Isotopic Data ◽  
Air Masses ◽  
Uranium Series ◽  
Nubian Aquifer ◽  
Stable Isotopic ◽  
Oxygen Isotopic ◽  
Carbonate Deposits

An Atlantic source of precipitation can be inferred from stable isotopic data (H and O) for fossil groundwaters and uranium-series-dated carbonate spring deposits from oases in the Western Desert of Egypt. In the context of available stable isotopic data for fossil groundwaters throughout North Africa, the observed isotopic depletions (δD −72 to −81‰; δ18O −10.6 to −11.5‰) of fossil (≥32,000 yr B.P.) groundwaters from the Nubian aquifer are best explained by progressive condensation of water vapor from paleowesterly wet oceanic air masses that traveled across North Africa and operated at least as far back as 450,000 yr before the present. The values of δ18O (17.1 to 25.9‰) for 45,000- to >450,000-yr-old tufas and vein-filling calcite deposits from the Kharga and Farafra Oases are consistent with deposition from groundwaters having oxygen isotopic compositions similar to those of fossil groundwaters sampled recently at these locations.

scholarly journals Quantitative Mineral Mapping of Drill Core Surfaces I: A Method for µXRF Mineral Calculation and Mapping of Hydrothermally Altered, Fine-Grained Sedimentary Rocks from a Carlin-Type Gold Deposit

2020 ◽  
Author(s):  
Rocky D. Barker ◽  
Shaun L.L. Barker ◽  
Siobhan A. Wilson ◽  
Elizabeth D. Stock
Keyword(s):  
Gold Deposit ◽  
Sedimentary Rocks ◽  
Potassium Feldspar ◽  
Ore Deposits ◽  
Drill Core ◽  
Raster Data ◽  
X Ray ◽  
Fine Grained ◽  
Core Samples ◽  
Wavelength Dispersive Spectrometry

Abstract Mineral distributions can be determined in drill core samples from a Carlin-type gold deposit, using micro-X-ray fluorescence (µXRF) raster data. Micro-XRF data were collected using a Bruker Tornado µXRF scanner on split drill core samples (~25 × 8 cm) with data collected at a spatial resolution of ~100 µm. Bruker AMICS software was used to identify mineral species from µXRF raster data, which revealed that many individual sample spots were mineral mixtures due to the fine-grained nature of the samples. In order to estimate the mineral abundances in each pixel, we used a linear programming (LP) approach on quantified µXRF data. Quantification of µXRF spectra was completed using a fundamental parameters (FP) standardless approach. Results of the FP method compared to standardized wavelength dispersive spectrometry (WDS)-XRF of the same samples showed that the FP method for quantification of µXRF spectra was precise (R2 values of 0.98–0.97) although the FP method gave a slight overestimate of Fe and K and an underestimate of Mg abundance. Accuracy of the quantified µXRF chemistry results was further improved by using the WDS-XRF data as a calibration correction before calculating mineralogy using LP. The LP mineral abundance predictions were compared to Rietveld refinement results using X-ray diffraction (XRD) patterns collected from powders of the same drill core samples. The root mean square error (RMSE) for LP-predicted mineralogy compared to quantitative XRD results ranges from 0.91 to 7.15% for quartz, potassium feldspar, pyrite, kaolinite, calcite, dolomite, and illite. The approaches outlined here demonstrates that µXRF maps can be used to determine mineralogy, mineral abundances, and mineralogical textures not visible with the naked eye from fine-grained sedimentary rocks associated with Carlin-type Au deposits. This approach is transferrable to any ore deposit, but particularly useful in sedimentary-hosted ore deposits where ore and gangue minerals are often fine grained and difficult to distinguish in hand specimen.

The Mina Justa Iron Oxide Copper-Gold (IOCG) Deposit, Peru: Constraints on Metal and Ore Fluid Sources

2021 ◽  
Author(s):  
Maria A. Rodriguez-Mustafa ◽  
Adam C. Simon ◽  
Laura D. Bilenker ◽  
Ilya Bindeman ◽  
Ryan Mathur ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Meteoric Water ◽  
Type I ◽  
Isotopic Data ◽  
Hydrothermal Processes ◽  
Fe Content ◽  
Stable Isotopic ◽  
Copper Gold ◽  
Iocg Deposit ◽  
Mg Content

Abstract Iron oxide copper-gold (IOCG) deposits are major sources of Cu, contain abundant Fe oxides, and may contain Au, Ag, Co, rare earth elements (REEs), U, and other metals as economically important byproducts in some deposits. They form by hydrothermal processes, but the source of the metals and ore fluid(s) is still debated. We investigated the geochemistry of magnetite from the hydrothermal unit and manto orebodies at the Mina Justa IOCG deposit in Peru to assess the source of the iron oxides and their relationship with the economic Cu mineralization. We identified three types of magnetite: magnetite with inclusions (type I) is only found in the manto, is the richest in trace elements, and crystallized between 459° and 707°C; type Dark (D) has no visible inclusions and formed at around 543°C; and type Bright (B) has no inclusions, has the highest Fe content, and formed at around 443°C. Temperatures were estimated using the Mg content in magnetite. Magnetite samples from Mina Justa yielded an average δ56Fe ± 2σ value of 0.28 ± 0.05‰ (n = 9), an average δ18O ± 2σ value of 2.19 ± 0.45‰ (n = 9), and Δ’17O values that range between –0.075 and –0.047‰. Sulfide separates yielded δ65Cu values that range from –0.32 to –0.09‰. The trace element compositions and textures of magnetite, along with temperature estimations for magnetite crystallization, are consistent with the manto magnetite belonging to an iron oxide-apatite (IOA) style mineralization that was overprinted by a younger, structurally controlled IOCG event that formed the hydrothermal unit orebody. Altogether, the stable isotopic data fingerprint a magmatic-hydrothermal source for the ore fluids carrying the Fe and Cu at Mina Justa and preclude significant input from meteoric water and basinal brines.

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