Journal Sciences News
Vacuum
25 May 2018
Editorial Board
Publication date: 25 May 2018
Source:Chemical Geology, Volume 487

25 May 2018
Response of the Changjiang (Yangtze River) water chemistry to the impoundment of Three Gorges Dam during 20102011
Publication date: 25 May 2018
Source:Chemical Geology, Volume 487 Author(s): Xiaodan Wang, Shouye Yang, Xiangbin Ran, Xiao-Ming Liu, Cl
25 May 2018
Rapid measurement of strontium in speleothems using core-scanning micro X-ray fluorescence
Publication date: 25 May 2018
Source:Chemical Geology, Volume 487 Author(s): Nick Scroxton, Stephen Burns, Pete Dawson, J. Michael Rhodes, Kaylee Brent, David McGee, Henk Heijnis, Patricia Gadd, Wahyoe Hantoro, Mike Gagan Speleothem trace element ratios such as Mg/Ca and Sr/Ca are increasingly used in speleothem paleoclimatology as a supplement to stable oxygen and carbon isotope ratios as proxies for past variability in the hydrologic system. Using multiple proxies together allows for a better understanding of both the local and distal hydrologic changes recorded in speleothem chemistry, and therefore of changes in past rainfall. Despite the potential benefits, trace element analysis of speleothems has yet to become widespread, which is likely due to the significant time and costs required by traditional trace element analytical techniques. In this study, we present an in-depth investigation into a rapid, relatively non-destructive and competitively priced technique for measuring Sr/Ca in speleothems: Core-Scanning micro X-ray Fluorescence (CS-
25 May 2018
A CO2 solubility model for silicate melts from fluid saturation to graphite or diamond saturation
Publication date: 25 May 2018
Source:Chemical Geology, Volume 487 Author(s): James Eguchi, Rajdeep Dasgupta A model based on a thermodynamic framework for CO2 concentrations and speciation in natural silicate melts at graphite/diamond-saturated to fluid-saturated conditions is presented. The model is simultaneously calibrated with graphite-saturated and fluid-saturated conditions allowing for consistent model predictions across the CCO buffer. The model was calibrated using water-poor (
25 May 2018
A pronounced fall in the CaCO3 saturation state and the total alkalinity of the surface ocean during the Mid Mesozoic
Publication date: 25 May 2018
Source:Chemical Geology, Volume 487 Author(s): Giovanni Aloisi Geochemical models suggest that the calcium carbonate saturation state (
25 May 2018
Dissolution and phase transformation processes of hausmannite in acidic aqueous systems under anoxic conditions
Publication date: 25 May 2018
Source:Chemical Geology, Volume 487 Author(s): Yao Luo, Wenfeng Tan, Steven L. Suib, Guohong Qiu, Fan Liu Hausmannite is the most widely distributed spinel-structured manganese oxide in soils and sediments. The transformation of this metastable manganese oxide to Mn(IV) oxides with higher adsorption capacity has attracted much research interest, while the transformation mechanisms and influencing factors still remain largely unknown, especially under acidic condition. In this work, the transformation processes of hausmannite at different pH values and the influence of cations were studied. Results indicated that hausmannite was transformed into manganite at pH
25 May 2018
From mixed flow reactor to column experiments and modeling: Upscaling of calcite dissolution rate
Publication date: 25 May 2018
Source:Chemical Geology, Volume 487 Author(s): Arnaud Bouissonni
15 May 2018
Dynamic changes of dissolved organic matter during nitrate transport in a loose-pore geothermal reservoir
Publication date: 25 May 2018
Source:Chemical Geology, Volume 487 Author(s): Li Zhao, Yu Zhao, Xinyi Wang, Jian Yang, Shaohe Luo, Yunfei Tian, Xiaoge Zhen The dynamic changes of dissolved organic matter (DOM) during nitrate transport were investigated to explore the relationship between carbon sources and the nitrate reduction process in a loose-pore geothermal reservoir. Batch experiments were performed at four temperature levels (4
15 May 2018
Editorial Board
Publication date: 15 May 2018
Source:Chemical Geology, Volume 486

15 May 2018
Structural controls of CO2 on Y, La and Sr incorporation in sodium-rich silicate - carbonate melts by in-situ high P-T EXAFS
Publication date: 15 May 2018
Source:Chemical Geology, Volume 486 Author(s): J. Pohlenz, A.D. Rosa, O. Mathon, S. Pascarelli, S. Belin, G. Landrot, V. Murzin, A. Veligzhanin, A. Shiryaev, T. Irifune, M. Wilke Carbonate-rich silicate and carbonate melts play a crucial role in deep Earth magmatic processes and their melt structure is a key parameter, as it controls physical and transport properties. Carbon-rich melts can be strongly enriched in trace elements, but the structural incorporation mechanisms of these elements are difficult to study because such melts generally cannot be quenched to glasses. In this contribution we investigate the influence of CO2 on the local environments of trace elements contained in silicate glasses with variable CO2 concentrations and in silicate and carbonate melts. The melts were studied in-situ at high pressure and temperature conditions using the Paris-Edinburgh press (2.2 to 2.6GPa and 1200 to 1500C). The compositions studied include sodium-rich peralkaline silicate melts and glasses and carbonate melts similar to those occurring naturally at Oldoinyo Lengai volcano. The local environments of yttrium (Y), lanthanum (La) and strontium (Sr) were investigated using extended X-ray absorption fine structure (EXAFS) spectroscopy. Main findings of the study suggest: (1) In peralkaline silicate glasses the local structure of Y is unaffected by the CO2 content. Contrary, a slight increase of oxygen bond lengths of Sr and La is inferred with increasing CO2 content in peralkaline glasses, while they remain constant in glasses of even higher peralkalinity independent of the CO2 content. (2) In silicate melts of different CO2 contents Y-O bond lengths are constant, while a slight increase within carbonate melt compositions is deduced. On the other hand, a steady bond lengths increase over the whole compositional range is inferred for La-O and Sr-O. This may well be explained by distinct preferences of these elements for specific local environments. Based on these new data, we suggest potential mechanisms for the structural incorporation of these elements, a key step towards understanding their partitioning behavior in natural magmatic systems.
15 May 2018
Variation in sub-arc mantle oxygen fugacity during partial melting recorded in refractory peridotite xenoliths from the West Bismarck Arc
Publication date: 15 May 2018
Source:Chemical Geology, Volume 486 Author(s): Antoine B
15 May 2018
Impact of dissolution of syngenetic and epigenetic minerals on coal permeability
Publication date: 15 May 2018
Source:Chemical Geology, Volume 486 Author(s): Hamed Lamei Ramandi, Min Liu, Sahand Tadbiri, Peyman Mostaghimi Permeability of coal is a key parameter in coalbed methane recovery. Minerals are known to occlude flow paths and reduce coal permeability. Herein, pore space variation of coal due to dissolution of syngenetic and epigenetic minerals is numerically simulated. A high-resolution helical micro-computed tomography (micro-CT) scanner is used to acquire 3D images from internal structure of a coal sample that contains both syngenetic and epigenetic minerals. Two subsets are then obtained from the micro-CT image and segmented to separate syngenetic minerals, epigenetic minerals and macerals. The syngenetic and epigenetic minerals individually and together are dissolved and their impact on porosity and permeability is studied. The minerals are identified through Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS). The dissolution process is performed based on a first order kinetic reactive model. The numerical model combines lattice Boltzmann and finite volume methods. The results show that coal permeability significantly increases when a reactive solution is introduced. It is observed that the permeability increase due to change of porosity is approximately 50% greater when only epigenetic minerals are dissolved. It is demonstrated that dissolving syngenetic minerals that are contiguous to the connected flow network can enhance the permeability through increasing the available connected void spaces. Also, it is shown that the gap, which at some cases occurs due to mineral detachment from the fracture wall, has a direct impact on dissolution performance. Overall, this study improves the understanding of dissolution phenomena in different types of coal minerals.
15 May 2018
Helium diffusivity and fluxes from a sedimentary basin (Permo-Carboniferous trough, Northern Switzerland)
Publication date: 15 May 2018
Source:Chemical Geology, Volume 486 Author(s): I. Tolstikhin, S. Tarakanov, M. Gannibal Abundances of radiogenic He and Ar isotopes, observed in ground waters of the Permian-Carboniferous terrigenous sediments (PCT) in Northern Switzerland, exceed those in the overlaying (Muschelkalk) and underlying (Crystalline basement) aquifers, eliminating external sources of these species. In this case a comparison of the observed abundances with those in situ generated sheds light on mobility of noble gases generated in the PCT. Detailed studies of the parent element and He isotope concentrations in the PCT rocks, mineral separates, pore and ground waters along with the data on
15 May 2018
Weathering processes, catchment geology and river management impacts on radiogenic (87Sr/86Sr) and stable (
10 May 2018
Influence of Th-rich mineral phases on UTh radioactive disequilibrium ages of sulfide deposits from the Okinawa Trough
Publication date: 15 May 2018
Source:Chemical Geology, Volume 486 Author(s): S. Nakai, A. Takamasa, T. Fujiwara, S. Toyoda, J. Ishibashi, R. Yoshizumi, T. Urabe Many samples of hydrothermal sulfide minerals from the Okinawa Trough yield 234U230Th radioactive disequilibrium ages that are inconsistent with the ages of coexistent barite obtained using electron spin resonance (ESR) method. These results contrast strongly against results obtained for the Southern Mariana Trough, for which the UTh radioactive disequilibrium ages are roughly consistent with the ESR ages. Sulfide minerals from the Okinawa Trough show large variation in U and Th abundances, suggesting open-system behavior. We infer that the interaction of hydrothermal fluids with thick terrigenous sediment caused large-scale migration of U and Th in the Okinawa Trough. The (234U/230Th) (232Th/230Th) plots for the sulfide samples from the Hatoma Knoll and the Izena Hole show two mixing trends for each site. The presence of Th-rich phase with high (230Th/234U) ratio seems to cause incorrect age estimates of the sulfide deposits.
10 May 2018
Editorial Board
Publication date: 10 May 2018
Source:Chemical Geology, Volume 485

10 May 2018
Molybdenum isotope variations in calc-alkaline lavas from the Banda arc, Indonesia: Assessing the effect of crystal fractionation in creating isotopically heavy continental crust
Publication date: 10 May 2018
Source:Chemical Geology, Volume 485 Author(s): Martin Wille, Oliver Nebel, Thomas Pettke, Pieter Z. Vroon, Stephan K
10 May 2018
Photo-stability of iron-phenolic complexes derived from peatland upon irradiation in waters under simulated sunlight
Publication date: 10 May 2018
Source:Chemical Geology, Volume 485 Author(s): Yiliu Wang, Wu Xiang, Weiling Yang, Sen Yan, Zhengyu Bao, Yu Liu Phenolics from peatlands have been proven to enhance the solubility of iron, even under alkali or saline conditions, by forming iron-phenolic complexes. However, the photo-stability of these complexes has received little attention thus far. Based on the investigation of water and peat samples in Jinchuan peatland, in northern China, simulated experiments using Gallic acid (GA) as a structural analog of peat-derived phenolic acid were carried out to clarify the mechanisms of photo-stability of iron-phenolic complexes. Our research confirmed that when the molar ratio of GA to Fe reaches 0.1:1, photolysis led to some Fe deposition. By comparing GA concentrations under aerobic/anaerobic conditions, we demonstrated that dissolved oxygen plays a key role, not only in GA autoxidation but also in photo-degradation of GA through direct and indirect photolysis. Besides, adding coexisting phenolic acids into GA/iron systems showed various effects, depending on the different functional groups, while the dominant species of phenolic acids in peatlands, such as p-cumaric acid and p-hydroxybenzoic acid, may still act as reactive oxygen species scavengers, protecting over 99% of the dissolved iron under solar irradiation. Our results indicate that by forming iron-organic complexes with certain phenolics from peatlands, dissolved iron can be effectively protected from precipitation during freshwater transport under solar irradiation, which has profound implications for controlling the limited primary production in certain marine areas.
10 May 2018
No 182W excess in the Ontong Java Plateau source
Publication date: 10 May 2018
Source:Chemical Geology, Volume 485 Author(s): Thomas S. Kruijer, Thorsten Kleine Small-scale W isotope variations in ancient and modern terrestrial rocks provide insights into Earth's accretion and early differentiation history as well as the long-term evolution of the Earth's mantle. Tungsten isotope studies on such rocks have exploited advances in mass spectrometry, both NTIMS and MC-ICPMS, which now permit the determination of W isotope ratios at unprecedented precision. While W isotope studies performed in different labs by MC-ICPMS and NTIMS generally exhibit excellent agreement, obtaining accurate W isotope data at this level of precision remains analytically challenging. For example, a recent NTIMS study reported a relatively large, +24
10 May 2018
Determinants of blood water
10 May 2018
Elemental concentration and organic petrology of unique liptinite-rich humic coal, canneloid shale, and cannel coal of Devonian age from Arctic Canada
Publication date: 10 May 2018
Source:Chemical Geology, Volume 485 Author(s): Fariborz Goodarzi, Thomas Gentzis Seventeen coal and carbonaceous shale samples taken from eight stratigraphic sections of the Devonian Hecla Bay and Weatherall formations in Arctic Canada, were examined using reflected light microscopy, instrumental neutron activation analysis (INAA), and inductively coupled plasma emission spectroscopy (ICPES). Samples consist of humic coal with 6279
10 May 2018
Signal or noise? Isolating grain size effects on Nd and Sr isotope variability in Indus delta sediment provenance
Publication date: 10 May 2018
Source:Chemical Geology, Volume 485 Author(s): Tara N. Jonell, Yuting Li, Jurek Blusztajn, Liviu Giosan, Peter D. Clift Radiogenic elements, such as neodymium (Nd) and strontium (Sr), are commonly used to decipher the provenance and weathering histories of bulk siliciclastic sediments worldwide, although increasing evidence for diagenetic and sediment transport-driven bias of isotope signatures calls into question the utility of bulk isotope compositions as effective tools. This study evaluates grain size-dependence and variability of Nd and Sr compositions in the Indus delta of Pakistan, documenting both a significant isotopic evolution and coarsening upward sequence during the last deglaciation (~15
10 May 2018
Riverine supply to the eastern Mediterranean during last interglacial sapropel S5 formation: A basin-wide perspective
Publication date: 10 May 2018
Source:Chemical Geology, Volume 485 Author(s): Jiawang Wu, Amalia Filippidi, Gareth R. Davies, Gert J. de Lange Organic-rich sapropel sediments were repeatedly deposited in the eastern Mediterranean Sea (EMS), in response to insolation-driven freshwater forcing. However, the exact freshwater sources and causal associated paleoclimate-related processes remain unresolved. Sapropel S5, formed during the insolation maximum of the last interglacial, is one of the most intensely developed sapropels of the Late-Quaternary. Here, detrital sediments of sapropel S5 obtained from 8 cores, together with 13 EMS surface samples, are analyzed for major elements, rare earth elements (REE), and Sr and Nd isotopes. This permits a basin-wide investigation of the source and distribution of river-borne material to the EMS for sapropel S5, and its comparison to the present-day and the Holocene sapropel S1 period. During the sapropel S5, there was minor Saharan dust input. The marked eastwest geochemical gradient in S5 detrital sediments across the EMS is therefore attributed to mixing between fluvial contributions, being Nile discharge, Aegean/Adriatic riverine inputs, and Libyan-Tunisian paleodrainage fluxes. The offshore distribution of Nile sediments during sapropel S5 was comparable to those during S1 and the present. The Nile sediment contribution appears to be only dominant for the Levantine Basin, decreasing to negligible values south of Crete. This rather limited sediment delivery, despite inferred increased runoff during S5, is related to denser vegetation cover on the Ethiopian Highlands. By contrast, small rivers around the Aegean (and Adriatic) Sea brought large amounts of detrital material into the EMS. This is particularly noticeable around Crete and the northern Ionian Sea. The enhanced riverine input is probably due to strong precipitation seasonality over the northern EMS borderlands, particularly for the early phase of the last interglacial maximum. Furthermore, there are substantial fluvial contributions from the Libyan-Tunisian margin to the Ionian Sea sediments, in particular during the last part of sapropel S5. The inferred river-borne material was transported via paleodrainage systems reactivated by intensified monsoon precipitation, and derived from central-Saharan mountains. Compared to sapropel S1, these S5-related paleodrainage fluxes were not only stronger, but also had a more predominant provenance from eastern rather than western Libya. In addition, a similar, averaged endmember of Saharan dust sources is revealed by REE signatures.
10 May 2018
Distinguishing slow cooling versus multiphase cooling and heating in zircon and apatite (U-Th)/He datasets: The case of the McClure Mountain syenite standard
Publication date: 10 May 2018
Source:Chemical Geology, Volume 485 Author(s): Wesley R. Weisberg, James R. Metcalf, Rebecca M. Flowers New zircon, titanite, and apatite (U-Th)/He (ZHe, THe, AHe) data for four samples of the 524
10 May 2018
Small-scale Sr and O isotope variations through the UG2 in the eastern Bushveld Complex: The role of crustal fluids
Publication date: 10 May 2018
Source:Chemical Geology, Volume 485 Author(s): Mathias Schannor, Ilya V. Veksler, Lutz Hecht, Chris Harris, Rolf L. Romer, Tawanda D. Manyeruke A detailed study of the Sr- and O- isotopic composition of minerals in the Upper Group 2 (UG2) unit of the eastern Bushveld Complex revealed significant variations in the pegmatoidal footwall pyroxenite and the UG2 chromitite layer itself. Initial 87Sr/86Sr ratios (Sri) of interstitial plagioclase in the footwall rocks are significantly higher than in adjacent rocks of the Critical Zone. The
5 May 2018
Corrigendum to Determination of Fe3+/
5 May 2018
Editorial Board
Publication date: 5 May 2018
Source:Chemical Geology, Volume 484

5 May 2018
A tribute to Professor Kazuhiro Suzuki Chemical Geology special issue Accessory mineral and trace element geochemistry
Publication date: 5 May 2018
Source:Chemical Geology, Volume 484 Author(s): Monika A. Kusiak, Daniel J. Dunkley, Takenori Kato, Krishnan Sajeev, Klaus Mezger
5 May 2018
Electron-microprobe dating of monazite: The story
Publication date: 5 May 2018
Source:Chemical Geology, Volume 484 Author(s): Jean-Marc Montel, Takenori Kato, Masaki Enami, Alain Cocherie, Friedrich Finger, Michael Williams, Michael Jercinovic This paper is a testimony of how electron microprobe dating of monazite was developed in the early days of this technique, in the 90's. Five contributions have been collected from Nagoya, Clermont-Ferrand, Orl
5 May 2018
Pseudo-fixed dead time circuit for designing and implementation of JEOL-type X-ray counting systems
Publication date: 5 May 2018
Source:Chemical Geology, Volume 484 Author(s): Takenori Kato, Kazuhiro Suzuki, Mi-Jung Jeen, Masayo Minami Quantitative electron probe microanalysis (EPMA) of trace elements using wavelength dispersive spectrometers (WDS) requires high probe current and/or accelerating voltage and long X-ray sampling times to measure weak X-ray signals from target materials. The X-ray count rate of a standard material is extremely high when measured under the same conditions. Consequently, the accuracy of the dead time correction becomes a significant issue for quantification. Accurate dead time correction requires an exact knowledge of the X-ray counting system, including the behavior of the proportional counter and electronic circuits. Each spectrometer has a specific dead time that depends on factors such as electronic circuit design, counter bias, and X-ray energies. The dead time also changes with aging degradation. A pseudo-fixed dead time correction circuit with non-extendable approximation is described that prevents systematic errors in quantitative EPMA caused by inappropriate dead time corrections. The circuit, which is added to the output of the single channel analyzer, includes one extendable and two non-extendable dead time generators with dead times of 0.68
5 May 2018
Improving U-Th-Pb electron microprobe dating using monazite age references
Publication date: 5 May 2018
Source:Chemical Geology, Volume 484 Author(s): Patrik Kone
5 May 2018
The giant monazite crystals from Manangotry (Madagascar)
Publication date: 5 May 2018
Source:Chemical Geology, Volume 484 Author(s): Jean-Marc Montel, Dieudonne Razafimahatratra, Philippe de Parseval, Franck Poitrasson, Bernard Moine, Anne-Magali Seydoux-Guillaume, Rapha
5 May 2018
Mass transport and fractionation during monazite alteration by anisotropic replacement
Publication date: 5 May 2018
Source:Chemical Geology, Volume 484 Author(s): A. Grand'Homme, E. Janots, A.M. Seydoux-Guillaume, D. Guillaume, V. Magnin, J. H
5 May 2018
REE-Th-U and Nd isotope systematics of monazites in magnetite- and ilmenite-series granitic rocks of the Japan arc: Implications for its use as a tracer of magma evolution and detrital provenance
Publication date: 5 May 2018
Source:Chemical Geology, Volume 484 Author(s): Keita Itano, Tsuyoshi Iizuka, Mihoko Hoshino Monazite [(Ce, La, Th) PO4], a common accessory mineral in low-Ca felsic rocks and a wide range of metamorphic rocks, is suitable for in situ UPb dating, rare earth element (REE) geochemistry, and Nd isotope tracer studies. To link monazite composition with igneous petrogenesis and differentiation, we carried out comprehensive LA-ICP-MS measurements of REE-Th-U abundances and Sm-Nd isotope ratios in monazites from magnetite-series (oxidized type) and ilmenite-series (reduced type) granitic rocks across the Japan arc. The data revealed systematic differences in monazite composition between magnetite-series and ilmenite-series samples, and between pegmatites and granites. In ilmenite-series granitic rocks, monazites from pegmatites showed larger negative Eu anomalies, lower light-REE/middle-REE ratios, and higher middle-REE/heavy-REE ratios than those from granites. These geochemical variations were attributed to significant fractional crystallization of feldspars, monazite, xenotime, and garnet during differentiation in relatively reduced peraluminous granitic magmas. In contrast, there was no remarkable difference in the REE fractionation pattern between magnetite-series pegmatites and granites. Furthermore, the magnitudes of the negative Eu anomalies in the magnetite-series monazites were smaller than those observed in the ilmenite-series samples. These features were interpreted to reflect the suppression of monazite, xenotime, and garnet fractionation and limited Eu incorporation into fractionating feldspars in relatively oxidized and non-peraluminous magmas. In addition, our data demonstrated intra-grain variations in REE-Th-U compositions in a monazite from the Masaki ilmenite-series pegmatite, despite its homogenous Nd isotope composition. These variations suggest that the core and rim of the grain crystallized from distinct magmas that were generated from similar crustal rocks, but were differentiated under different conditions. A comparison of the present data with previously reported data indicates that igneous monazites from granitic rocks are distinct from a wide range of metamorphic monazites in REE-Th-U composition, especially due to their larger negative Eu anomalies. This finding highlights the potential utility of monazite REE-Th-U systematics as a provenance indicator for detrital monazites.
5 May 2018
SHRIMP UPbTh xenotime (YPO4) geochronology: A novel approach for the correction of SIMS matrix effects
Publication date: 5 May 2018
Source:Chemical Geology, Volume 484 Author(s): A.J. Cross, I.S. Williams Xenotime (YPO4) occurs in a wide range of geological environments, but its potential to establish the timing of mineralisation and sediment diagenesis has been the focus of most recent studies. Xenotime in these settings usually has a relatively low uranium content (typically <1000ppm) compared to igneous xenotime and occurs as microscopic crystals (<50
5 May 2018
Geochemical characterisation of xenotime formation environments using U-Th
Publication date: 5 May 2018
Source:Chemical Geology, Volume 484 Author(s): Neal J. McNaughton, Birger Rasmussen Xenotime (YPO4) is a trace component in many metasedimentary and some igneous rocks, altered rocks and many hydrothermal ore assemblages, where it forms in response to a range of different processes from igneous crystallisation to low-temperature early diagenesis. Due to its wide range of formation temperatures, its suitability and isotopic robustness for reliable U-Pb geochronology, dissolution/precipitation characteristics during overprint events, and widespread occurrence, it is one of the most valuable minerals for U-Pb geochronology leading to four-dimensional (4D) studies of many terranes. The formation environment of xenotime can be deduced from careful petrography and reliable U-Pb in-situ geochronology within a 4D framework. Further, xenotime is a physically robust mineral during sediment transport and may carry distinctive geochemical fingerprints, including age, to secondary environments. From published works, we review the U-Th-contents of well-characterised examples of xenotime formation to provide chemical fingerprints, which assist in identifying the xenotime formation environment. Although the U-Th characteristics of xenotime from all formation environments show considerable overlap, we make the following observations which may be distinctive of some ore formation environments: (i) hydrothermal xenotime formed from low salinity ore fluids (e.g. iron ore and orogenic gold deposits) trend to have the lowest U-contents (<100ppm U) and U/Th (<4), in contrast to xenotime formed from higher salinity ore fluids (Sn-W and base metal deposits); (ii) xenotime associated with unconformity-related U-ores have the highest U-contents at U/Th>10; (iii) diagenetic xenotime has the most variable and highest U/Th, whereas (iv) xenotime from Precambrian orogenic gold deposits has the least variable and lowest U/Th. Petrogenetic inferences from these observations for ore deposit research and exploration include: (i) support for the homogenising effect of the crustal scale of the fluid system in Precambrian orogenic gold deposits, and (ii) the potential for distinctive U-Th geochemical fingerprints for U ores and some Au ores. These characteristics may be reflected in detrital xenotime grains recovered from routine exploration sampling programs.

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5 May 2018
Rare earth elements and Sm-Nd isotope redistribution in apatite and accessory minerals in retrogressed lower crust material (Bergen Arcs, Norway)
Publication date: 5 May 2018
Source:Chemical Geology, Volume 484 Author(s): Emilie Janots, H
5 May 2018
Juxtaposition of allochthonous terranes in the central Korean Peninsula: Evidence from zircon U-Pb ages and O-Hf isotopes in Jurassic granitoids
Publication date: 5 May 2018
Source:Chemical Geology, Volume 484 Author(s): Hui Je Jo, Albert Chang-sik Cheong, Keewook Yi, Xian-Hua Li The eventual docking of an exotic continental mass over the course of a Wilson cycle is marked by intracontinental sites of prograde metamorphism, contractional deformation, and syn- or post-collisional magmatism. This study shows that inherited premagmatic zircon in subsequently emplaced granitoid rocks provides another line of evidence for the collisional orogeny. Following the continental collision between the North and South China Cratons, Jurassic granitoids intruded widely throughout the central Korean Peninsula in association with the subduction of the Paleo-Pacific plate. The latest Early to Middle Jurassic (177167Ma) granitoids occur throughout the cratonic Gyeonggi Massif, whereas Early Jurassic (194184Ma) granitoids occur locally along the Okcheon Metamorphic Belt to the southeast of the massif. These two spatiotemporal groups differ profoundly in their age patterns and O-Hf isotopic signatures of inherited zircon. The younger group yields a typically North China-like Archean-Paleoproterozoic (mostly 2.51.8Ga) zircon inheritance. In contrast, inherited zircons from the older group exhibit exclusively Neoproterozoic (ca. 0.90.7Ga) and Paleozoic (ca. 0.4Ga) cluster along with Archean-Paleoproterozoic populations. The exotic feature of the protolith of the older group is further indicated by significantly lower
5 May 2018
Timing and duration of regional metamorphism in the Kagasawa and Unazuki areas, Hida metamorphic complex, southwest Japan
Publication date: 5 May 2018
Source:Chemical Geology, Volume 484 Author(s): Kenji Horie, Yukiyasu Tsutsumi, Mami Takehara, Hiroshi Hidaka UPb zircon geochronology of two granite intrusions containing bluish
5 May 2018
New insight into disturbance of U-Pb and trace-element systems in hydrothermally altered zircon via SHRIMP analyses of zircon from the Duluth Gabbro
Publication date: 5 May 2018
Source:Chemical Geology, Volume 484 Author(s): Mami Takehara, Kenji Horie, Tomokazu Hokada, Shoichi Kiyokawa Redistribution and retention behavior of major (Zr, Si, O, and Hf) and trace (Li, Al, P, K, Ca, Ti, Mn, Fe, rare earth elements (REE), Pb, U, and Th) elements in zircon during hydrothermal alteration were investigated by a sensitive high-resolution ion microprobe (SHRIMP). AS3 zircons collected from the Duluth Complex, U.S.A. were classified into three domains: Type-A comprise domains with a darker backscattered electron (BSE) and cathodoluminescence (CL) response; Type-B comprise domains with fine fractures, and; Type-C comprise domains where the dark response areas in CL are bright in BSE and vice versa, and are free of fractures. The Type-A domains are characterized by discordant U-Pb ages, light REE enrichment, depletion of Zr and Si, and higher contents of Ca, Mn, Fe, Al, Li, and K, which suggests that elemental redistribution occurred during hydrothermal alteration. Although the Type-B domains also show depletion of Zr and enrichments of Ca, Mn, Fe, Al, Li and K, the Zr contents and the contents of Ca, Mn, Fe, Al, Li, and K are higher and lower than those of the Type-A domains, respectively. This feature of the Type-B domains suggests existence of thin altered domains surrounding the fractures like clads. Therefore, there is a possibility that the Type-B domains are mixtures of the altered clads and unaltered domains. The Ca contents show a correlation with the Zr contents, which indicates that the Ca content is a suitable criterion for identifying hydrothermally altered zircon. There is no obvious correlation between Ca content and disturbance of the U-Pb system, but enrichment of some trace elements and REE's are correlated to the degree of Ca enrichment. The monovalent elements (Li and K) and the trivalent elements (especially light REE) are enriched at Ca contents of >1
5 May 2018
Lu-Hf ratios of crustal rocks and their bearing on zircon Hf isotope model ages: The effects of accessories
Publication date: 5 May 2018
Source:Chemical Geology, Volume 484 Author(s): F. Bea, P. Montero, J.F. Molina, J.H. Scarrow, A. Cambeses, J.A. Moreno All other factors being equal, the calculation of zircon Hf two stage model ages (T DM Hf) depends on the particular Lu/Hf value assumed for the magmatic source, the effect being more pronounced as the age difference between zircon and magmatic source increases. It is generally considered that the Lu/Hf measured in the zircon-hosting rock does not represent the composition of the source because of potential garnet or zircon fractionation. Accordingly, most authors either assume a single fixed value for Lu/Hf source , often Lu/Hf
5 May 2018
Variscan post-collisional cooling and uplift of the Tatra Mountains crystalline block constrained by integrated zircon, apatite and titanite LA-(MC)-ICP-MS U-Pb dating and rare earth element analyses
Publication date: 5 May 2018
Source:Chemical Geology, Volume 484 Author(s): Aleksandra Gaw
5 May 2018
Peak to post-peak thermal history of the Saglek Block of Labrador: A multiphase and multi-instrumental approach to geochronology
Publication date: 5 May 2018
Source:Chemical Geology, Volume 484 Author(s): Monika A. Kusiak, Daniel J. Dunkley, Martin J. Whitehouse, Simon A. Wilde, Anna Sa
Available online 24 April 2018
87Sr/86Sr compositional linkage between geological and biological materials: A case study from the Toyota granite region of Japan
Publication date: 5 May 2018
Source:Chemical Geology, Volume 484 Author(s): M. Minami, K. Suzuki The strontium isotope value (87Sr/86Sr) is often used to identify the origins of agricultural products and the movements of ancient people. Maps delineating the distribution of 87Sr/86Sr values can therefore be of great use. Previous 87Sr/86Sr distribution maps of stream sediments covering small areas of Japan largely reflect the 87Sr/86Sr values of underlying bedrock. It remains unclear, however, whether the 87Sr/86Sr values of stream sediments may also reflect the 87Sr/86Sr values of the nearby vegetation and fauna. We sought to resolve this question by investigating the relationship between 87Sr/86Sr values in biological samples and in geological samples from the sites from which the biological samples grew. The geological samples consisted of soil samples from 2 paddy fields and 13 bed sediment samples (grain size <180
Available online 24 April 2018
Super-deep, TSR-controlled Phanerozoic MVT type Zn-Pb deposits hosted by Zechstein reservoir carbonate, Lower Saxony Basin, Germany
Publication date: Available online 24 April 2018
Source:Chemical Geology Author(s): Marta So
Available online 24 April 2018
Redox zonation and organic matter oxidation in palaeogroundwater of glacial origin from the Baltic Artesian Basin
Publication date: Available online 24 April 2018
Source:Chemical Geology Author(s): Joonas P
Available online 23 April 2018
Synergies in elemental mobility during weathering of tetrahedrite [(Cu,Fe,Zn)12(Sb,As)4S13]: Field observations, electron microscopy, isotopes of Cu, C, O, radiometric dating, and water geochemistry
Publication date: Available online 24 April 2018
Source:Chemical Geology Author(s): Juraj Majzlan, Stefan Kiefer, Julia Herrmann, Martin
Available online 21 April 2018
Formation of epithermal Sn-Ag-(Zn) vein-type mineralization at the Pirquitas deposit, NW Argentina: Fluid inclusion and noble gas isotopic constraints
Publication date: Available online 23 April 2018
Source:Chemical Geology Author(s): Louis Desanois, Volker L
20 April 2018
Introducing a geochemical screen to identify geologically meaningful U-Pb dates in fossil teeth
Publication date: Available online 21 April 2018
Source:Chemical Geology Author(s): Stephanie Greene, Larry M. Heaman, S. Andrew DuFrane, Thomas Williamson, Philip J. Currie Previous studies have shown that radiometric dating of fossils can be complicated by post-fossilisation alteration. A key challenge to obtaining geologically meaningful fossilisation dates in bioapatite is identifying regions that have remained relatively undisturbed since the time of fossilisation. In order to determine whether a geochemical indicator can be used to identify least-disturbed regions, we combine in situ trace element analysis and U-Pb geochronology of fossil teeth from the Arroyo Chijuillita Member, New Mexico, and the Dinosaur Park Formation, Alberta. The reliability of these U-Pb dates is supported by good agreement between the isotope dilution thermal ionization mass spectrometry (61.5

Editorial Board
Publication date: 20 April 2018
Source:Chemical Geology, Volume 483


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