Laser Ablation Inductively-coupled Mass Spectrometry Research Articles

Geochronology and geochemistry of zircon from Early to Middle Devonian granitic and felsic volcanic rocks from the Cashes Ledge igneous suite, central Gulf of Maine, USA

New zircon U–Pb, trace element, and Lu–Hf laser ablation inductively coupled mass spectrometry (LA-ICP-MS) data are presented for five Early to Middle Devonian granitic and felsic volcanic rocks from the Cashes Ledge igneous suite, central Gulf of Maine, USA. These samples were previously analyzed by U–Pb LA-ICP-MS and whole-rock geochemical methods and the new data generally corroborate the earlier results. Coarse-grained alkali-feldspar granite from northwest of the Fundy magnetic anomaly, the interpreted fault boundary in the offshore between Gondwanan microcontinents Ganderia to the northwest and Avalonia to the southeast, yielded a crystallization age of 414 ± 2 Ma. Southeast of the inferred fault, crystallization ages are 385 ± 3 Ma and 386 ± 3 Ma for two crystal tuff samples near the fault, 403 ± 3 Ma for an alkali-feldspar granite ~50 km southeast of the fault, and 399 ± 5 Ma for syenogranite ~25 km southeast of the fault, which also yielded inherited grains at ~1.3 Ga and between 613 ± 15 Ma and 558 ± 9 Ma. Lu–Hf LA-ICP-MS data for zircon retaining igneous crystallization ages have εHf(t) between 2.9 and 13.1 and model ages based on felsic sources between 0.52 and 1.04 Ga, reflecting a mix of late Mesoproterozoic (Avalonian?) basement and primitive melt, possibly in an extensional setting. Zircon Nb/Hf ratios generally greater than 0.001 indicate a predominately within-plate/anorogenic/rift setting, consistent with their whole-rock chemistry. U/Yb-Nb/Yb and U/Yb-Hf tectonic setting discrimination diagrams show ocean island to continental arc signatures, with a stronger continental arc signature for the syenogranite. Most zircon grains have Eu/Eu* values less than 0.1, indicating a crustal thickness of ~30 km or less at the time of their crystallization.

Elemental cycles in the coralline alga Neogoniolithon hauckii as a recorder of temperature variability in the Mediterranean Sea

Coralline algae play important ecological roles throughout the photic zone of the world’s oceans. Recent studies have shown that attached-living coralline algae can contain records of past climate variability. So far, algal-based paleo-reconstructions are mainly available from mid- to high-latitudes, while in low latitude and temperate regions only few examples exist. Here, we investigate samples from the attached-living encrusting coralline algal species Neogoniolithon hauckii (Rothpletz) R.A Townsend & Huisman [= Neogoniolithon mamillosum (Hauck) Setchell & L.R. Mason, nom illeg.] from a temperate site in the Mediterranean Sea to assess its potential as an environmental recorder. The specimens were collected at different water depths (20 and 40 m) in the Columbretes Islands (Spain). Sclerochronological analysis of sectioned samples revealed seasonal growth patterns. Mg/Ca, Li/Ca, and Ba/Ca ratios were measured in the algal skeletons using laser ablation inductively coupled mass spectrometry (LA-ICP-MS) in ultra-high resolution. We report a mean vertical extension rate of 1.1 to 1.2 mm/year (based on analysis of Mg/Ca cycles in 40 m and 20 m samples), representing the first growth rate measurement for this species. In addition, subannual banding patterns were mapped, measured, and could be linked to high frequency variability in laser-analyzed Mg/Ca ratios. Elemental ratios analyzed in Neogoniolithon hauckii were compared to in situ water temperatures measured at the water depth of sample collection. Our results show significant positive relationships between algal Mg/Ca (R=0.55) as well as Li/Ca ratios (R=0.46) and in situ measured temperature data (40 m specimen). Ba/Ca ratios show no significant correlation to temperature and may be influenced by other factors. These data suggest potential of this species for climate reconstructions in warm-temperate regions as Neogoniolithon hauckii is not only widely distributed in the Mediterranean, but also one of the few species that may be used as a temperature archive for mesophotic coralligenous assemblages that are strongly affected by the recent anthropogenic temperature rise. Further calibration studies are needed to test the element-temperature relationships on samples with longer growth records and in different settings and water depths.

Ancient Glass of South Asia: Archaeology, Ethnography and Global Connections. Alok Kumar Kanungo and Laure Dussubieux, eds. Singapore: Springer, 2021. xxvi + 557 pp., 59 b&w + 245 colour illustrations. Hardcover US$160, ISBN: 9789811636554; softcover US$140, ISBN: 9789811636578; ebook US$109, ISBN: 9789811636561.

Asian Perspectives, Vol. 62, No. 2 © 2023 by the University of Hawai‘i Press. Ancient Glass of South Asia: Archaeology, Ethnography and Global Connections. Alok Kumar Kanungo and Laure Dussubieux, eds. Singapore: Springer, 2021. xxvi + 557 pp., 59 b&w + 245 colour illustrations. Hardcover US$160, ISBN: 9789811636554; softcover US$140, ISBN: 9789811636578; ebook US$109, ISBN: 9789811636561. Reviewed by Ian C. FREESTONE, UCL Institute of Archaeology The marked expansion in the archaeometry of glass which took place in the first decade of the twenty-first century has led to an explosion of interest in glass beads and bangles. Desirable, robust, and portable, they hold important information on trade and connectivity which can be revealed by the analysis of their chemical constituents. While this potential of chemical analysis has been understood for decades (e.g., Basa et al. 1991; Brill 1987; Singh 1989), it is only recently that it has been fully realized, largely due to the application of the technique of laser ablation inductivelycoupled mass spectrometry (LA-ICP-MS). This method allows a rapid, accurate, and precise analysis of around 60 elements in glass artifacts and, critically, is essentially non-destructive, leaving only a sub-millimetre scar on the surface of the artifact. Where earlier typological work inferred likely longdistance connections (Francis 1990), chemistry has confirmed them. The resultant growth in understanding has served to emphasise the important role of the Indian sub-continent, which was arguably the major producer of glass beads in the last two millennia. Indian beads are found as far afield as eastern Africa and northwestern Europe and are also widely distributed in southeastern and southern Asia. Furthermore, the continuation into the modern period of traditional methods of making and working with glass and glazes allows important insights into the methods and organization of the production of glass ornaments through ethnographic observation and literary accounts. The present book brings together recent and ongoing work on the archaeology, archaeometry, and ethnoarchaeology of South Asian glass, edited by two leading researchers in their respective areas. The chapters are developed from lectures delivered by the eminent list of authors at a conference in Gandhinagar in 2019 and may be considered a good reflection of the state of the art. However, this substantial 550-page book is far from a standard conference volume. It strives not only to provide a comprehensive coverage of its subject matter, but also to serve as an introduction to the study of glass by including a number of chapters by established researchers on broader issues; by and large, it is very successful. The book opens with several chapters providing introductory and background information. Rehren opens with a summary of the current state of play in our understanding of the origins of glass in Egypt and Mesopotamia. In the context of the present volume, Rehren’s chapter in particular brings home how important the analysis of glass and manufacturing debris from Late Bronze Age production sites has been to current understanding, although at present evidence from production sites in South Asia is largely lacking. The following chapter by Gratuze, Schibille, and Pactat covers the radical changes in glassmaking technology that occurred in Europe and West Asia in the later first millennium C.E., in particular the transition from the use of soda from the natron lakes of Egypt to soda obtained from the ashes of halophytic plants. Not only is this an outstanding example of the application of chemical analysis to a technical change, focusing on chronological and regional variations, but it also provides a good introduction to the major glass types which moved along the silk road from West to East and which are encountered later on in the volume. Kenoyer provides a long, comprehensive review of major importance on the faience and glazed steatite of the Indus tradition, focusing on Harappa. This brings together new work and insights with a substantial but dispersed literature, much of which has been generated by the author Early online release of article in press. and his collaborators and which is not always easily accessible. Kenoyer is skeptical about the identification of so-called “steatite faience” or glazed crushed steatite. He calls for more detailed examination of samples removed from...

Evidence for the ∼ 1.4 Ga Picuris orogeny in the central Colorado Front Range

We present the first evidence for sedimentation and new evidence for penetrative deformation and metamorphism in the central Colorado Front Range associated with the ∼ 1.48–1.35 Ga Picuris orogeny. This orogeny has recently been recognized in New Mexico, Arizona and southern Colorado and may be part of a larger active accretionary margin that includes the ∼ 1.51–1.46 Ga Pinware and Baraboo events, in eastern Canada and central US respectively, that preceded the amalgamation of the Rodinian supercontinent. We demonstrate that in addition to ∼ 1.4 Ga reactivation of northeast-trending Paleoproterozoic shear zones, regional folding occurred in an area south of Mt. Evans, away from these shear zones.Detrital zircon from one quartzite yielded U–Pb laser ablation inductively coupled mass spectrometry (LA-ICPMS) major age populations of ∼ 1.81–1.61 Ga and ∼ 1.49–1.38 Ga, and minor ones of ∼ 1.90 Ga and ∼ 1.56 Ga. The Paleoproterozoic and ∼ 1.49–1.38 Ga populations have numerous local and regional sources. The ∼ 1.56 Ga age population may represent a minor exotic population as recognized in Defiance, Arizona the Yankee Joe and Blackjack Formations in Arizona, the Four Peaks area in Arizona, and the Tusas and Picuris Mountains in New Mexico. Alternatively it may be a result of mixing between zircon age domains reflecting the older and younger populations, or Pb loss from 1.81 to 1.61 Ga zircon.In-situ LA-ICPMS U–Pb analysis on monazite from four biotite schist samples yielded ∼ 1.74 Ga and ∼ 1.42 Ga age populations, and separate populations that show ∼ 1.68–1.47 Ga and ∼ 1.39–1.33 Ga age spreads. The ∼ 1.74 Ga and ∼ 1.68–1.47 Ga populations may be detrital or metamorphic. Monazite ages between ∼ 1.6 Ga and ∼ 1.5 Ga may be due to the mixing of age domains or Pb loss, because metamorphism during that time has not been recognized in Laurentia. The ∼ 1.42 Ga and ∼ 1.39–1.33 Ga populations are most likely metamorphic and consistent with the age of the ∼ 1.48–1.35 Ga Picuris orogeny. The evidence for ∼ 1.4 Ga sedimentation, and especially regional folding and metamorphism in the central Colorado Front Range indicate that the impact and extent of the Picuris orogeny in the southwestern U.S. are larger than previously thought.

Metal(loid) Deportment in Sulfides from the High-Grade Core of the Bingham Canyon Porphyry Cu-Mo-Au Deposit, Utah

Abstract Porphyry deposits supply the bulk of the world’s Cu and Mo and significant amounts of Au, as well as other minor and trace metal(loid)s, including Ag, Re, Te, Pd, Se, Bi, Zn, and Pb. Porphyry deposits are gaining in importance as a source of critical raw materials with the increasing global demand for these commodities. To date, minor and trace metal(loid)s are still commonly recovered as by-products from porphyry ores without prior characterization of their host mineralogy that could inform more efficient processing and improved recoveries. We report a comprehensive metal(loid) deportment study on a complete vein paragenetic series in samples from the northwestern high-grade zone of the Bingham Canyon Cu-Mo-Au porphyry deposit, Utah. The polyphase Bingham stock comprises an early premineralization equigranular monzonite phase that was intruded by a series of five successive, ore-related porphyry intrusions. Veins with hypogene Cu-(Fe) sulfide assemblages from all five porphyry intrusions were characterized for their trace metal(loid) contents by laser ablation-inductively coupled-mass spectrometry (LA-ICP-MS). It was found that bornite and digenite contain elevated Bi, Ag, Te, and Se relative to chalcopyrite, whereas the latter contains elevated concentrations of Co, Ga, and In. A stepwise decline in sulfide abundance occurs over the porphyry intrusion sequence and is more pronounced in digenite and bornite than in chalcopyrite. The related diminishing concentration per rock volume (inventory) of Bi, Ag, Te, and Se in the youngest porphyry dikes could have been caused in part by a geochemical change in the mineralizing fluid supply across successive intrusive-hydrothermal cycles. Element mapping of exsolved digenite within bornite revealed characterstic partitioning of metal(loid)s between bornite and digenite; most notably Ag, but also Te and Au are enriched in digenite relative to enclosing bornite. Bornite domains within these composite grains reveal complex zonation of Sn, In, and Bi, which are attributed to stress-induced diffusion within bornite, resulting from the digenite exsolution process. The selective partitioning of metal(loid)s between bornite and digenite is likely a common feature in many porphyry Cu deposits, given the fundamental mineralogical characteristics of these two sulfides. Our results contribute to an improved understanding of the distribution (from mineral to deposit scale) of critical trace metal(loid)s in porphyry deposits, particularly those containing exsolved digenite. This knowledge can be applied to determine more accurately the value of ore resources, to improve geometallurgical models and by-product recoveries, and to help limit the environmental effects of metal(loid) dispersion.

Petrogenesis of an Early Cretaceous Xiabie Co I‐type Granite in Southern Qiangtang, Tibet: Evidence from Geochemistry, Geochronology, Rb‐Sr, Sm‐Nd, Lu‐Hf and Pb isotopes

AbstractCretaceous magmatism is widely distributed on both sides of the Bangong–Nujiang suture zone (BNSZ). These rocks record the subduction to closure history of the Bangong–Nujiang Tethys Ocean (BNO) and the collisional history between the Lhasa (LS) and Qiangtang (QT) terranes. The Xiabie Co granite in Nyima County, which located on the southern margin of the QT terrane, Tibet. In this study, whole‐rock geochemistry; Rb‐Sr, Sm‐Nd, and Pb isotopes; and laser ablation inductively coupled mass spectrometry (LA‐ICP‐MS) zircon U‐Pb ages and Lu‐Hf isotopes of the Xiabie Co granite in the Nyima area have been studied to constrain its petrogenesis and tectonic setting. Our study can help explain the tectonic evolution of the BNSZ and crust‐mantle interaction. Zircon U‐Pb dating indicates that the granite was emplaced at ca. 120 Ma. The granite contains a small amount of hornblende and has high silicon (SiO2 = 73.97–78.03 wt%), potassium (K2O = 4.75–6.53 wt%), and total alkali (K2O + Na2O = 7.98–8.98 wt%) contents; low calcium content (CaO = 2.33–4.11 wt%); and variable A/CNK (1.00–1.18) and A/NK (1.09–1.22) values. The P2O5 content of the granite negatively correlated with the SiO2 content. Thus, the Xiabie Co granite is a weakly peraluminous I‐type granite belonging to the high‐K calc‐alkaline to Shoshone series. It is enriched in light rare earth elements (LREEs) and relatively depleted in heavy rare earth elements (HREEs), with LREE/HREE ratios of 8.03–16.40 and LaN/YbN ratios of 10.2–27.1. Samples show right‐leaning chondrite‐normalized rare earth element patterns with pronounced negative Eu anomalies (Eu/Eu∗ = 0.67–0.76). The primitive‐mantle‐normalized trace element spider diagrams of the samples are right‐leaning zigzag curves, showing relative enrichment in large‐ion lithophile elements (LILEs, e.g., Rb, Th, U, and K) and depletion in high‐field‐strength elements (HFSEs, e.g., Nb, P, Ti, and Yb) and displaying striking Sr and Ba negative anomalies. The granite εHf(t) values were positive (2.9–9.9), whereas the whole‐rock εNd(t) values were negative (–2.841 to –2.33). The calculated (87Sr/86Sr)t, (206Pb/204Pb)t, (207Pb/204Pb)t, and (208Pb/204Pb)t values are 0.7014–0.7057 (0.7044 on average), 18.422–18.851 (18.670 on average), 15.625–15.642 (15.633 on average), and 38.332–38.681 (39.571 on average), respectively. On the basis of the aforementioned data, we propose that the Xiabie Co granite was derived from a primitive magma that originated from partial melting of juvenile lower crust with the addition of mantle materials. In addition, strong fractional crystallization occurred during the rock‐forming process. Given the geodynamic setting, our new data, together with previously reported achievements, imply that the Xiabie Co granite was formed during the LS–QT collision.

Using whole rock and in situ pyrite chemistry to evaluate authigenic and hydrothermal controls on trace element variability in a Zn mineralized Proterozoic subbasin

The mid-Proterozoic stratigraphy of the McArthur Basin (Australia) contains some of the most well-preserved sedimentary rocks of Precambrian age, which are also host to giant, clastic dominant (CD-type) massive sulfide Zn deposits. The most recently discovered CD-type deposit (the Teena deposit) is located in the Teena subbasin and hosted by the 1.64 Ga Barney Creek Formation. The Teena subbasin, therefore, provides the perfect natural laboratory for evaluating authigenic and hydrothermal controls on trace element (TE) variability, both of which contribute to paleoenvironmental reconstructions and ore deposit models. As the Teena deposit formed beneath the paleoseafloor, this also provides the opportunity to evaluate TE zonation around a fossilized subseafloor replacement hydrothermal system. In situ laser ablation inductively coupled mass spectrometry (LA-ICP-MS) has been used to define compositional end members in diagenetic and hydrothermal pyrite. The overgrowth of hydrothermal sulfides on diagenetic pyrite is associated with TE anomalism (Tl, Pb, As, Zn) that extends > 100 meters above the main high grade sulfide mineralization the Teena subbasin. The vertical zonation in TEs is consistent with the infiltration of hydrothermal fluids into overlying hangingwall sediments that were undergoing diagenesis. Bulk rock lithogeochemical data record covariation between total organic carbon (TOC) and a suite of TEs (Mo, Co, Ni, V). We suggest this was caused by local hydrographic factors during deposition of the Barney Creek Formation. High TOC/P molar ratios, resulting from regeneration of P in a euxinic water column, are associated with an interval overlying the main maximum flooding surface in the subbasin. The relationships between TOC, P and TEs resemble the redox architecture of a silled basin rather than an open marine margin. Sulfidic conditions developed during periods of high productivity, which were linked to nutrient supply that was enhanced by connectivity with surrounding water masses. The evidence of redox bistability, involving a delicate balance between ferruginous (anoxic, non-sulfidic) and euxinic (sulfidic) conditions, is consistent with recent models for other mid-Proterozoic sedimentary units. Nevertheless, there was a strong localised (101 km2) control on the authigenic and hydrothermal TE chemistry of the Barney Creek Formation in the Teena subbasin, which highlights a key challenge when extrapolating from data collected in partially restricted intracontinental marine settings.

In situ multiple sulfur isotopes and chemistry of pyrite support a sedimentary source-rock model for the Linwang Carlin-type gold deposit in the Youjiang basin, southwest China

The Linwang gold deposit is a representative example of Carlin-type gold deposits in Youjiang basin, southwest China. High-grade ores are hosted in silicified and brecciated siltstone, sandstone, and mudstone of the Middle Triassic and are controlled by high-angle reverse faults. Optical microscopy pyrite texture, in situ laser ablation-inductively coupled mass spectrometry (LA-ICP-MS) trace elements, and secondary ion mass spectrometry (SIMS) multiple sulfur isotopes analyses are used to examine the different types of pyrites to constrain the sources of reduced sulfur and metals for the Linwang deposit.Petrography and pyrite chemistry studies distinguished three generations of pyrite: Pre-ore pyrite (Py 1) and ore pyrites (Py 2 and Py3). Pre-ore pyrite is framboidal, anhedral to euhedral pyrite with highest concentrations of Co, Ni, and Pb and is interpreted to have a sedimentary (diagenetic) origin. Ore pyrites were formed by hydrothermal fluids via sulfidation of Fe-bearing minerals in the host rocks. They commonly rimed and partially replaced the pre-ore pyrite and have an As-rich inner rim (Py 2) and an Au-rich outer rim (Py 3) with lowest contents of Co, Ni, and Pb. All pyrites contain Au, As, Sb, Cu, Tl, and Se, with increasing concentrations from Py 1 to Py 3.In situ SIMS multiple S isotope analyses show that all pyrites in the Linwang deposit have narrow ranges of δ34S values, with average of +5.13‰ for Py 1, +4.84‰ for Py 2, and +4.53‰ for Py 3, and near zero of Δ33S values (−0.02‰ to +0.03‰), suggesting that the S within the Linwang deposit was most likely sourced from the Triassic sedimentary rocks that host the deposit. A near zero Δ33S signature in all pyrites indicates no record of the assimilation of Archean sulfur, implying the deep basement of Archean rocks beneath the basin were not involved the formation of the Linwang deposit.Oxygen and hydrogen isotope compositions of ore fluids (δ18OH2O = +11.7‰ to +16.5‰, δD = −71‰ to −57‰) indicate a metamorphic origin. Based on these data, we propose a sedimentary source-rock model for the Linwang deposit in which the ore fluids were generated by release of previous Au-bearing sedimentary pyrites during metamorphism of sedimentary rocks. The stress relaxation of Yanshanian orogeny resulted in the ore fluids flowed upward along the fault zones into structural highs where they reacted with Fe-bearing minerals in the host rocks to deposit Au-rich pyrite. The preconcentration of Au, As, and Sb in sedimentary pyrite and gold deposition process are key to the formation of the Linwang deposit and may apply to the genesis of other Carlin-type gold deposits in the Youjiang basin.

New prospects to the multi-elemental analysis of single microcrystal of apatite by total-reflection X-ray fluorescence spectrometry

The elemental analysis of apatite minerals is an important study that is utilized in several applications in geology, biology, medicine, agriculture, technology, and environmental remediation. Laser ablation inductively coupled mass spectrometry (LA-ICP-MS) is a routine method for the elemental analysis of apatite microcrystals in geological applications. In this study, we propose a new method for the analysis of single grain of apatite with a mass of a few μg using total-reflection X-ray fluorescence spectrometry (TXRF), which is faster, cheaper, and easier in quantification procedure than LA-ICP-MS. The direct preparation of the single apatite microcrystal on the quartz carrier using nitric acid digestion and quantification using the stoichiometric value of P as an internal standard allows to obtain the major, minor, and trace elements (from K to U) simultaneously. For the choice of the internal standard in TXRF, the Raman spectroscopy is applied to obtain the information of the mineral phases and their distribution formed in the apatite sample after the digestion procedure. Validation of the proposed TXRF method is conducted by the analysis of reference materials (Durango and Otter Lake) and comparison of results with the TXRF for bulk-type of apatite and LA-ICP-MS methods.

Bioimaging of Pb by LA-ICP-MS and Pb isotopic compositions reveal distributions and origins of Pb in wheat grain

Atmospheric heavy metal deposition in agroecosystems has increased recently, especially in northern China, which poses serious risks to crop safety and human health via food chain. Wheat grains can accumulate high levels of Pb even when wheat is planted in soils with low levels of Pb. However, the influence of atmospheric deposition on the accumulation and distribution of Pb in wheat grain is still unclear. A field survey was conducted in three districts (A: a district with industrial and traffic pollution; B: a district with traffic pollution; and C: an unpolluted district) in Hebei Province, North China. The grain of wheat cultivated in district A accumulated more Pb from soil and atmospheric deposition than those in other districts, and the bran from district A contained 3.50 and 2.04 times more Pb than those from districts B and C, respectively. The Pb distribution pattern in wheat grain detected by laser ablation inductively coupled mass spectrometry (LA-ICP-MS) was characterized by accumulation mostly in the pericarp and seed coat rather than in the crease, embryo and endosperm. Furthermore, Pb isotopic data showed that airborne Pb was the major source (>50%) of Pb in wheat grain. Interestingly, average contributions of Pb from atmospheric deposition to white flour (78.22%) were higher than its contributions to bran (56.27%). In addition, wheat flag leaves were exposed to PbSO4 at the booting stage, and much greater Pb accumulation (0.33-0.48 mg/kg) was observed in exposed wheat grain than in the control (P < 0.05), PbSO4 constituted most (82.80-100%) of the Pb in the wheat grain. In summary, the results confirmed the efficient foliar Pb uptake and transfer from atmospheric deposition into wheat grain. It would be a new sight for understanding the contribution of airborne Pb to Pb accumulation in wheat grains.

Origin of β-cristobalite in Libyan Desert Glass: The hottest naturally occurring silica polymorph?

Abstract Identifying and determining the origin of β-cristobalite, a high-temperature silica polymorph, in natural samples is challenging as it is rarely, if ever, preserved due to polymorphic transformation to α-cristobalite at low temperature. Formation mechanisms for β-cristobalite in high-silica rocks are difficult to discern, as superheating, supercooling, bulk composition, and trace element abundance all influence whether cristobalite crystallizes from melt or by devitrification. Here we report a study of α-cristobalite in Libyan Desert Glass (LDG), a nearly pure silica natural glass of impact origin found in western Egypt, using electron microprobe analysis (EMPA), laser ablation inductively coupled mass spectrometry (LA-ICP-MS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD). The studied grains are mostly 250 μm in diameter and consist of ~150 μm wide cores surrounded by ~50 μm wide dendritic rims. Compositional layering in LDG continues across cristobalite grains and mostly corresponds to variations in Al content. However, layering is disrupted in cores of cristobalite grains, where Al distribution records oscillatory growth zoning, whereas in rims the high Al occurs along grain boundaries. Cristobalite cores thus nucleated within layered LDG at conditions that allowed mobility of Al into crystallographically controlled growth zones, whereas rims grew when Al was less mobile. Analysis of 37 elements indicates little evidence of preferential partitioning; both LDG and cristobalite are variably depleted relative to the upper continental crust, and abundance variations correlate to layering in LDG. Orientation analysis of {112} twin systematics in cristobalite by EBSD confirms that cores were formerly single β-cristobalite crystals. Combined with published experimental data, these results provide evidence for high-temperature (&amp;gt;1350 °C) magmatic crystallization of oscillatory zoned β-cristobalite in LDG. Dendritic rims suggest growth across the glass transition by devitrification, driven by undercooling, with transformation to α-cristobalite at low temperature. This result represents the highest formation temperature estimate for naturally occurring cristobalite, which is attributed to the near pure silica composition of LDG and anomalously high temperatures generated during melting by meteorite impact processes.

First U-Pb dating of fossilized soft tissue using a new approach to paleontological chronometry

Abstract Previous U-Pb dating of fossils has had only limited success because of low uranium content and abundance of common Pb as well as element mobility during late diagenesis. We report the first accurate U-Pb dating of fossilized soft tissue from a Pliocene phosphatized bivalve mold using laser ablation–inductively coupled mass spectrometry (LA-ICPMS). The fossilized soft tissue yields a diagenetic U-Pb age of 3.16 ± 0.08 Ma, which is consistent with its late Pliocene stratigraphy and similar to the oldest U-Pb age measured on accompanying shark teeth. Phosphate extraclasts give a distinctly older age of 5.1 ± 1.7 Ma, indicating that they are likely detrital and may have furnished P, promoting phosphatization of the mold. The U-Pb ages reported here along with stratigraphic constraints suggest that diagenesis occurred shortly after the death of the bivalve and that the U-Pb system in the bivalve mold remained closed until the present. Shark teeth collected from the same horizon show variable resetting due to late diagenesis. Data were acquired as line scans in order to exploit the maximum Pb/U variation and were regressed as counts, rather than ratios, in three-dimensional space using a Bayesian statistical method.

Determination of Elemental Composition in Soft Biological Tissue Using Laser Ablation Inductively Coupled Plasma Mass Spectrometry: Method Validation.

Determination of elemental concentrations in biological tissue is fundamental to many environmental studies. Analytical methods typically used to quantify concentrations in such studies have minimum sample volumes that necessitate lethal or impactful collection of tissues. Laser ablation inductively coupled mass spectrometry (LA-ICP-MS) has small sample volume requirements and offers environmental practitioners an opportunity to employ low-impact sample collection methods. Environmental applications of LA-ICP-MS are limited by the lack of validated methods, partly due to the need for dry samples and scarcity of matrix-matched certified reference materials (CRMs). This study validates an LA-ICP-MS method to determine concentrations of 30 elements in soft biological tissue (fish ovary and muscle). Tissue samples (median: 0.48 grams (g); inter-quartile range: 0.30 g to 0.56 g wet weight) were dehydrated, powdered, compressed into pellets (weighing approximately 0.03 g) and analyzed using LA-ICP-MS alongside three matrix-matched CRMs. The method yielded concentration determinations for CRM elements that were typically accurate to within 30% of theoretical concentrations, and precise (relative standard deviation <20%). These results were repeatable: accuracy rarely deviated from theoretical values by more than 20%, and precision rarely exceeded 33%. Determinations for biological samples were replicable irrespective of tissue (ovary or muscle). There was good linearity between analyte signal strength and theoretical concentration (median R2 ≥ 0.981 for all elements) across ranges typically encountered in environmental studies. Concentrations could not be consistently obtained (i.e., determined concentrations were typically below detection limits) for boron, vanadium, molybdenum, and cadmium in muscles, and arsenic in both ovaries and muscles; however, detection limits were sufficiently low for most environmental contexts. Further methodological refinement could include the incorporation of spiked standards to extend linear ranges, and fine-tuning instrument parameters to obtain smoother signal intensities for rare elements. The method presented promotes the use of low-impact sample collection methods while enabling high-quality determinations of elemental concentrations in biological tissues.

Early Permian Granitic Magmatism in Middle Part of the Northern Margin of the North China Craton: Petrogenesis, Source, and Tectonic Setting

The late Palaeozoic was an important period of tectonic evolution for the northern margin of the North China Craton (NCC). The source(s) and tectonic setting of early Permian granitoid rocks emplaced along the northern margin of the NCC are still unclear. These granitoids formed between ~295.4–276.1 Ma (uncertainties ranging from ±1.5 to ±7.8 Ma) according to zircon laser ablation inductively coupled mass spectrometry (LA-ICP-MS) and sensitive high-resolution ion microprobe (SHRIMP) U-Pb data. The Dadongou (DDG) pluton is an A1-type granite and the Dananfangzi (DNFZ) pluton is an A2-type granite. The Erdaowa (EDW), Lisicun (LSC), Wuhai (WH) and Gehuasitai (GHST) plutons are I-type granites. The Yuanbaoshan (YBS) dykes are diorite and syenodiorite. All the granitoids are enriched in large ion lithophile elements and light rare earth elements, depleted in high field strength elements and have negative εNd(t) and εHf(t) values. The A1-type granite was formed by the melting of the mafic crust. The A2-type granite was derived from partial melting of tonalite gneiss from the NCC crust and mantle materials. The EDW, LSC, WH and GHST granites mainly originated from partially melted granulite, with some mantle input. The YBS dykes are formed by the magma mixing of hot mantle melt and the relatively cold crustal magma. The northern margin of the NCC experienced anorogenic and collision tectonic stages, and the structural setting started to transform to post-collision at the later period of early Permian.

Accurate Measurement of Copper Overload in an Experimental Model of Wilson Disease by Laser Ablation Inductively Coupled Plasma Mass Spectrometry.

Wilson disease is a rare inherited autosomal recessive disorder. As a consequence of genetic alterations in the ATP7B gene, copper begins to accumulate in the body, particularly in the liver and brain. Affected persons are prone to develop liver cancer and severe psychiatric and neurological symptoms. Clinically, the development of corneal Kayser-Fleischer rings and low ceruloplasmin concentrations (<20 mg/dL) are indicative of Wilson disease. However, the detection of elevated hepatic copper content (>250 µg/g dry weight) alone is still considered as the best but not exclusive diagnostic test for Wilson disease. Presently, specific copper stains (e.g., rhodanine) or indirect staining for copper-associated proteins (e.g., orcein) are widely used to histochemically visualize hepatic copper deposits. However, these procedures only detect lysosomal copper, while cytosolic copper is not detectable. Similarly, elemental analysis in scanning electron microscope with energy dispersive X-ray analysis (EDX) often leads to false negative results and inconsistencies. Here, we tested the diagnostic potential of laser ablation inductively-coupled mass spectrometry (LA-ICP-MS) that allows quantitative analysis of multiple elements. Comparative studies were performed in wild type and the Atp7b null mouse model. We propose LA-ICP-MS as a versatile and powerful method for the accurate determination of hepatic copper in people with Wilson disease with high spatial resolution.

Zinc distribution within breast cancer tissue of different intrinsic subtypes

PurposeTo show feasibility of laser ablation inductively coupled mass spectrometry (LA-ICPMS) for analysis of zinc content and concentration in breast cancer tissue and to correlate this with validated prognostic and predictive markers, i.e. histological grading and expression of steroid receptors (estrogen receptor, ER; progesterone receptor, PR) and human epidermal growth-factor receptor 2 (Her2).Methods28 samples of human invasive ductal breast cancer tissue were subclassified into groups of four different intrinsic subtypes according to the expression of ER, PR and Her2 by immunohistological staining and then analyzed for zinc content and distribution by LA-ICPMS applying a calibration technique based on spiked polyacrylamide gels. A correlation of zinc concentration with histological grading and molecular subtypes was analyzed.ResultsConsistent with results of a pilot-study LA-ICPMS was feasible to show zinc accumulation in cancerous tissue, even more adjacent healthy stroma was with proportional increase of zinc. Zinc levels were most elevated in triple-positive (TPBC) and in triple-negative (TNB) breast cancers.ConclusionLA-ICPMS was feasible to confirm a connection between zinc and grade of malignancy; furthermore, focusing on a correlation of zinc and intrinsic breast cancer subtypes, LA-ICPMS depicted an upwards trend of zinc for “high-risk-cancers” with highest levels in Her2-positive and in triple-negative (TNBC) disease. The currently uncommon alliance of clinicians and analytical chemists in basic research is most promising to exploit the full potential of diagnostic accuracy in the efforts to solve the enigma of breast cancer initiation and course of disease.

Partitioning and distribution of silver in sediment-hosted Cu-Ag deposits: Evidence from the Ghanzi-Chobe Belt portion of the Kalahari Copper Belt

The Khoemacau Mining (KCM) Cu-Ag deposits in northwestern Botswana are comprised of several mineralised zones, including from south to north: the Banana Zone (made up of the Chalcocite Zone, New Discovery, North Limb, South Limb Definition, and the North East Fold), Mango, Zone 5, Zone 5 North, Boseto, Zeta NE, and Zone 6. The KCM Cu-Ag deposits are characterised by two styles of mineralisation that include disseminated and structurally controlled styles of mineralisation, both typified by the scarcity of Ag-bearing minerals. Laser ablation inductively coupled mass spectrometry (LA-ICP-MS) and electron probe microanalysis (EPMA) techniques were employed to (i) track the sources of Ag by assessing the Ag budget of the sulphide phases, (ii) assess the partitioning and distribution of Ag in coexisting sulphide phases, and (iii) outline the mode of occurrence of Ag in the host sulphides. Bornite, chalcocite, wittichenite, tetrahedrite-like mineral, covellite, and galena were observed to be Ag-endowed. Bornite and tetrahedrite-like mineral are the principal hosts of Ag and contain, on average, up to 2090 and 4107 ppm Ag, respectively. But when bornite coexists with chalcocite, Ag preferentially partitions into chalcocite (mean Ag concentrations range from 423 to 1050 ppm) than in bornite (mean Ag concentrations range from 201 to 309 ppm). In the chalcocite-wittichenite assemblage, Ag partitions equally in these phases with mean concentrations of 1890 and 1854 ppm, respectively. Galena from the North East Fold contains a significant amount of Ag (mean 477 ppm) than that one from Zone 5, which is Ag-poor (mean up to 87 ppm). Unlike the spatially associated sulphides, chalcopyrite, however, is a poor host for Ag (mean concentration 1.3–104 ppm). The LA-ICP-MS data demonstrated that Ag is essentially bound in the crystal lattice of bornite, chalcocite, wittichenite, tetrahedrite-like mineral, covellite, and locally galena, as shown by the homogeneous distribution of Ag in the elemental maps, small to medium standard deviations (averaging 2–44% of the mean) and relatively flat time-resolved depth profiles. However, large variations in the Ag concentration between laser spots (averaging 51–70% of the mean) from the same sample, as observed in some bornite II grains from the New Discovery and the North East Fold mineralised zones, may indicate the presence of Ag-rich micro to nanoparticles in bornite II. The initial mineralising fluid is thought to have been saturated in Ag and precipitated Ag-rich phases in the mineralised zones southwest of the KCM Property, including the Chalcocite Zone, New Discovery, North Limb, South Limb Definition, and the North East Fold. Subsequently, it became Ag-under-saturated with time as it precipitated Ag-poor phases in the mineralised zones northeast of the KCM Project (such as Zone 5). The positive correlations (R > 0.60) displayed between Ag and As, Se, Sb, Hg, Te, and Bi in the Cu-(Fe)-sulphides demonstrate that these elements could be used as pathfinder elements in sediment-hosted Cu-Ag deposit exploration.

Fluid properties and origins of the Lannigou Carlin-type gold deposit, SW China: Evidence from SHRIMP oxygen isotopes and LA-ICP-MS trace element compositions of hydrothermal quartz

Oxygen isotope and trace elements characteristics of ore-related quartz from Lannigou gold deposit, a typical fault-control second largest Carlin-type Au deposit in SW China, provide valuable information about the properties and origins of the ore-forming fluids. Previous works has focused on vein quartz instead of ore-related jasperoid-like quartz grain due to hard separation. Based upon different cathodoluminescence (CL) textural patterns and intensities observed within the quartz, four generations of quartz from this deposit were identified: Quartz I is sedimentary detrital quartz; Quartz II is syn-mineralization jasperoid-like quartz intergrown with and/or containing fine (<10 μm) As-bearing pyrite and arsenopyrite; Quartz III is late-mineralization veinlet quartz with a small of medium-coarse-grained (about 50–100 μm) As-bearing pyrite; and Quartz IV is the post-mineralization drusy thick-veined quartz. Analyses by sensitive high-resolution ion microprobe (SHRIMP) and laser ablation inductively coupled mass spectrometry (LA-ICP-MS) were used to determine O isotope and trace elements compositions of quartz formed in different stages. The trace elemental (e.g., Al, Li, Ge, Ti) variation of quartz from Quartz II to IV reflect the effects of fluid saturation in CO2 as the result of decarbonization reactions, followed by a progressive fall in CO2, whereas the fluid pH and intensity of argillic alteration increase, progressively. The range of δ18OVSMOW values in Quartz II (12.1–24.8‰) is wide but narrows in Quartz III (24.1–27.8‰) and IV (24.3–26.9‰). The estimated fluid δ18O values of early- or main-stage (calculated from Quartz II) is 3.2–15.9‰, the late-stage (calculated from Quartz III) is 12.5–16.2‰, and the post-stage (calculated from Quartz IV) is 9.0–11.5‰. It is suggested that the ore-forming fluids of Lannigou gold deposit reflect a mixed source: a low O isotope end-member that was magmatic- or basement related, whereas the high O isotope end-member may have been fluid interacted with wall-rock, whose influence strengthened during the mineralization episode. The narrow δ18OVSMOW ranges of Quartz III and IV also suggest that any meteoric water influence on the late hydrothermal system was weak.

Multiphase U-Pb geochronology of sintered breccias from the Steen River impact structure, Canada: Mixed target considerations for a Jurassic-Cretaceous boundary event

In situ U-Pb geochronology has been conducted using laser ablation inductively coupled mass spectrometry (LA-ICP-MS) on shocked and thermally metamorphosed apatite, titanite, and zircon grains from the Steen River impact structure, Canada. The dated relict mineral phases occur within impact melt-bearing breccias that underwent post-deposition sintering at 450 °C > T < 800 °C. Apatite yields a refined lower intercept age of 141 ± 4 Ma, which we interpret as the best estimate age for the Steen River impact event. Titanite was only partially reset; yielding a lower intercept age of 113 ± 41 Ma. Zircon yields a lower intercept impact age of 120 ± 14 Ma, which is considered a minimum best-estimate impact age. The most reset zircon analyses that control this lower intercept are complicated by combinations of common-Pb incorporation and recent Pb loss associated with granularized and radiation-damaged (metamict) domains. All three phases preserve Paleoproterozoic crystalline basement ages, with a single concordant 206Pb/238U age of 1914 ± 39 Ma from apatite, an upper intercept age of 1882 ± 11 Ma from zircon, and an upper intercept age of 1842 ± 9 Ma from titanite. For apatite, the degree of isotopic resetting is largely thermally controlled, with the extent of reset closely associated with textural setting (degree of grain armouring, melt proximity and sample temperature) and, to a lesser extent, by shock/thermally generated microstructures (i.e., planar fractures, micro-vesicles, and recrystallized domains). While titanite records an impact age that falls within error of apatite and zircon, the majority of grains experienced only partial isotopic resetting, which we attribute to incomplete Pb loss associated with rapid cooling and post-depositional sintering of the breccia matrix below the titanite closure temperature (∼800 °C). In zircon, ancient (impact) Pb loss was facilitated along defect-related, fast-diffusion pathways within pre-impact metamict domains, shock defects, and via recrystallization. These same domains were also subject to recent (post-impact) Pb loss and common Pb contamination, significantly compromising the reliability of zircon ages. The distribution of U-Pb ratios in apatite and titanite is unlike those obtained in crystalline targets, a feature we interpret to be characteristic of impact structures developed in mixed (sedimentary – crystalline) targets, such as Steen River. In this case, disaggregated melt systems create thermal regimes distinct from those derived from predominantly igneous/metamorphic targets. With an age of 141 ± 4 Ma, Steen River joins the Dellen (Sweden), Gosses Bluff (Australia), Mjølnir (Barents Sea), and Morokweng (South Africa) impact structures in being formed at, or close to, the Jurassic-Cretaceous boundary.

Focused ion beam for improved spatially-resolved mass spectrometry and analysis of radioactive materials for uranium isotopic analysis

The ability to acquire high-quality spatially-resolved mass spectrometry data is sought in many fields of study, but it often comes with high cost of instrumentation and a high level of expertise required. In addition, techniques highly regarded for isotopic analysis applications such as thermal ionization mass spectrometry (TIMS) do not have the ability to acquire spatially-resolved data. Another drawback is that for radioactive materials, which are often of interest for isotopic analysis in geochemistry and nuclear forensics applications, high-end instruments often have restrictions on radioactivity and non-dispersibility requirements. We have applied the use of a traditional microanalysis tool, the focused ion beam/scanning electron microscope (FIB/SEM), for preparation of radioactive materials either for direct analysis by spatially-resolved instruments such as secondary ion mass spectrometry (SIMS) and laser ablation inductively-coupled mass spectrometry (LA-ICP-MS), or similarly to provide some level of spatial resolution to techniques that do not inherently have that ability such as TIMS or quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS). We applied this preparation technique to various uranium compounds, which was especially useful for reducing sample sizes and ensuring non-dispersibility to allow for entry into non-radiological or ultra-trace facilities. Our results show how this site-specific preparation can provide spatial context for nominally bulk techniques such as TIMS and Q-ICP-MS. In addition, the analysis of samples extracted from a uranium dioxide fuel pellet via all methods, but especially NanoSIMS and LA-ICP-MS, showed enrichment heterogeneities that are important for nuclear forensics and are of interest for fuel performance.