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Catalytic degradation of anthraquinones-containing H2O2 production effluent over layered Co-Cu hydroxides: Defects facilitating hydroxyl radicals generation

Year: 2020
Products: NWR213;
Authors: Guo, X;Hu, T;Meng, B;Sun, Y;Han, Y;
Journal: Applied Catalysis B: Environmental

Anthraquinones from H2O2 production effluent (AHE) was remediated over a Co-Cu Layered Double Hydroxide (LDH) through a Fenton-like reaction process. The variation of synthesis pH value has found to significantly influence the catalyst performances for hydroxyl radical generation. Defects (oxygen vacancies) in the catalyst surface which facilitates H2O2 decomposition was systematically studied with adjusting the synthesis pH value. The framework of catalyst with LDH feature was thoroughly characterized by several spectroscopy techniques. The formation of Co-O-Cu oxo-bridged bond is assumed to be responsible for the electron transfer and the generation of defects. However, the surface electronic structure was altered with the changes in Co and Cu contents. The defect-rich LDH framework with abundant defects (oxygen vacancies) promote electron transfer, and H2O2 dissociation are primarily to account for the excellent catalytic performance. The application of this catalyst and its optimization of operational parameters in AHE removal were thoroughly performed as well.

Hinterland setting and composition of an Oligocene deep rift-lake sequence, Gulf of Tonkin, Vietnam: Implications for petroleum source rock deposition

Year: 2020
Products: NWR213;
Authors: Rizzi, M;Fyhn, M;Schovsbo, N;Korte, C;Hovikoski, J;Olivarius, M;Thomsen, T;Keulen, N;Thuy, N;Hoang, B;Dung, B;Toan, D;Abatzis, I;Nielsen, L;
Journal: Marine and Petroleum Geology

Most SE Asian oil accumulations are sourced from Paleogene lacustrine mudstones. Even so, the mechanisms controlling formation of these source rocks are not fully understood. Bach Long Vi Island, located in the northwestern South China Sea, offers a unique opportunity to study these mechanisms. A continuous, 800 m thick, organic rich and highly oil-prone, lacustrine section was investigated in outcrop and in a continuously cored section. The Oligocene deep-lake succession formed in the Bach Long Vi Graben that connects the Beibuwan Basin with the Yinggehai-Song Hong Basin. Petrography, detrital zircon U-Th-Pb geochronology and heavy mineral assemblages of sandstone intervals document a locally derived sediment source isolated from the Red River. Orientations of ripple cross lamination in gravity flow sands indicate axial sediment transport along the graben. Combined with the local structural configuration, this suggests that sediments were derived from the Qixi High through a relay ramp located about 10 km south of the island. Rare earth and major elements, detrital zircon ages, sandstone petrography and garnet composition, suggest a dominantly Ordovician – Silurian aged felsic and metasedimentary hinterland. The limited sediment supply from the small hinterland allowed tectonic subsidence to keep pace with graben infill. This promoted the establishment of a long-lived, deep lake favorable for source rock generation. In addition, heavy mineral and geochemical data document an unusually high content of detrital phosphate minerals in the investigated section indicative of a phosphate-rich hinterland. Tropical leaching resulted in an extraordinary high phosphorus input into the lake that catalyzed a high organic productivity and promoted the generation of highly prolific, oil-prone source rocks. The study documents that hinterland size and composition play a primary role in lacustrine source rock deposition. Comparable petroleum source rocks are likely to exist in other ancient rift basins surrounded by small, phosphate-rich hinterlands sheltered from significant sediment input.

The origin of low-ca olivine from ultramafic xenoliths and host basaltic lavas in a back-arc setting, James Ross Island, Antarctic Peninsula

Year: 2019
Products: UP213;New Wave;
Authors: Altunkaynak, ;Ünal, A;Howarth, G;Aldanmaz, E;Nývlt, D;
Journal: Lithos

The James Ross Island Volcanic Group (JRIVG) at the northern tip of the Antarctic Peninsula is composed of various types of volcanic rocks erupted during the Late Miocene to Late Pleistocene. The sub-aerial lavas are the most abundant erupted products within the suite and are represented by alkali olivine basalts that contain significant amounts of ultramafic xenoliths. Precise determination of chemical compositions of olivine by electron microprobe and LA-ICP-MS reveals more than one compositionally distinct olivine population in the xenoliths and the host lavas. The majority of the olivine grains from the xenolith suite are remarkable for their high Mg/Fe ratios (>Fo88) and low-Ca contents (<500 ppm) and are similar in composition to the mantle olivine, while some others, despite their similarly low-Ca abundances, are characterized by significantly lower Mg/Fe (Fo88) from the basaltic lavas also have low Ca contents compared to MORB olivine at similar Fo, indicating an arc-melt like volatile content of the primary magma. Evaluation of minor and trace element relative abundances in olivine further indicate that the alkaline basalts in the JRIVG are the products of peridotite-dominated partial melting of a volatile-rich mantle source with signatures of mantle hydration most probably promoted by preceding subduction events. The results from olivine chemistry, when combined with the evaluation of primary melt compositions, appear to be consistent with the view that the primary magmas from which the JRIVG basalts were derived are the results of partial melting of a mantle domain that has experienced hydrous silicate melt metasomatism through interaction of peridotitic upper mantle rocks with melts of a slab-derived component, most probably generated by dehydration melting of subducted oceanic crust.

Proterozoic Kivakka layered mafic-ultramafic intrusion, Northern Karelia, Russia: Implications for the origin of granophyres of the upper boundary group

Year: 2019
Products: NWR213;
Authors: Bychkova, YV;Mikliaeva, EP;Koptev-Dvornikov, EV;
Journal: Precambrian Research

Granophyric rocks on Earth are enigmatic and may be investigated by detailed sampling, empirical method and modeling. This work presents recent results on the 2445 ± 5 Ma Kivakka layered mafic-ultramafic intrusion in Northern Karelia, Russia, in particular, leucocratic lenses in the upper cumulative zone. Based on detailed sampling, mineralogical and petrologic investigation coupled with COMAGMAT petrologic modeling, the following sequence of the fractional crystallization of the main rock-forming minerals is established: olivine, olivine + orthopyroxene, orthopyroxene, orthopyroxene + plagioclase, orthopyroxene + plagioclase + augite, plagioclase + augite + pigeonite. We propose a petrologic model of the leucocratic granophyric rock origin from the residual melt produced at late stages of evolution of the Kivakka massif via closed-system fractional crystallization and convective mixing of magma in the chamber. Comparison of the granophyric rocks with lunar KREEP and granophyric rocks of other terrestrial massifs is performed based on the major and trace element composition of the rocks and minerals. We believe that the Proterozoic granophyric rock origin on Earth may be comparable to the origin of the lunar KREEP rocks due to high differentiation degree of the parental basaltic magma.

Arc related dioritic-granodioritic magmatism from southeastern Peninsular Malaysia and its tectonic implication

Year: 2019
Products: UP213;New Wave;
Authors: Hazad, F;Ghani, A;Lo, C;
Journal: Cretaceous Research

In Peninsular Malaysia, Late Cretaceous (95-76 Ma) plutons are found within the Eastern Belt. Their compositions are diverse, ranging from biotite granite, hornblende granodiorite, diorite, and gabbro. The Aur Pluton is the easternmost body and is exposed in the Johore Archipelago, southeast of Peninsular Malaysia. The rock types vary from diorite, quartzmonzodiorite and granodiorite. Ar-Ar stepheating age of the diorite and zircon U/Pb age of the granodiorite yielded ages of 77.9 ± 2 Ma and 79 ± 0.7 Ma, respectively. The overall major and trace element trends are consistent with two magmatic pulses, i.e., diorite-quartz monzodiorite and granodiorite. The diorite-quartz monzodiorites are characterized by high Fe2O3 (6.7–8.3 wt.%), CaO (5.5–7.6 wt.%), MgO (2.9–4.1 wt.%) and high but variable Sr concentrations (570–1300 ppm). The granodiorites have significantly higher total alkalicontent (8.49–8.91%), with high K2O concentrations (3.8–4.6%) and low Fe2O3 (4.7–6.5%), CaO (2.7–3.9%) and MgO (1.4–2.0%) concentrations. Low Nb/U and distinct Pb anomalies suggest that both rock types are likely derived from the crust. Furthermore, elevated LREE and trace element contents for the granodiorites, e.g., FTh (10–20 ppm), Pb (10–30 ppm), and U (2–5 ppm), also indicate that upper crustal components are involved in the magma generation. The dioritic rocks are chemically classified as calc-alkaline volcanic arc (VAG) rocks, but they also have field relationships and mineralogies typically associated with an active continental margin (ACM).

Granulite-facies gneisses and meta-igneous xenoliths from the Campo de Calatrava volcanic field (Spain): Implications for the tectonics of the Variscan lower crust

Year: 2019
Products: UP213;NewWave;
Authors: Puelles, P;Gil Ibarguchi, J;García de Madinabeitia, S;Sarrionandia, F;Carracedo-Sánchez, M;Fernández-Armas, S;
Journal: Lithos

The microstructural, petrofabric and geochronological study of deep-seated xenoliths from the La Encomienda volcano (Neogene Campo de Calatrava Volcanic Field) has helped to characterize the nature and dynamics of processes operative in the lower crust and subcontinental mantle domains of the Central Iberian Zone in the Iberian Massif (Spain). We present the finding of three new xenolith types: noritic andesine meta-anorthosites, aluminous granulites and felsic granulites. Plagioclase (andesine), hypersthene, ilmenite, apatite and zircon make up the mineral assemblage in equilibrium in the anorthosite xenoliths, whereas K-feldspar (sanidine), antiperthitic plagioclase (oligoclase-andesine), quartz, sillimanite, garnet, rutile and biotite conform the mineral assemblage in the aluminous granulites. Felsic granulites differ from the aluminous type in the smaller amount of garnet, the occurrence of perthitic microcline and the lack of sillimanite and biotite. The presence of significant fabrics in the constituent minerals indicates that they underwent high-temperature deformations representative of low crustal domains.

Geochronology and petrogenesis of the Xiongmei Cu-bearing granodiorite porphyry in North Lhasa subterrane, central Tibet: Implication for the evolution of Bangong-Nujiang metallogenic belt

Year: 2019
Products: NWR193;ESI;
Authors: Wang, Y;Ma, X;Qu, X;Chen, W;
Journal: Ore Geology Reviews

Bangong-Nujiang metallogenic belt is a recently recognized post-subduction porphyry-skarn Cu polymetallic metallogenic belt in Tibet. The Xiongmei Cu-bearing granodiorite porphyry was newly found in the middle segment of this belt. In this study, we combined zircon U-Pb ages, Hf isotopic, REEs data, whole-rock Sr-Nd isotopic data, and whole-rock geochemical data to constrain the geochronology, petrogenesis and metallogenic features of the Xiongmei Cu-bearing granodiorite porphyry. Zircon U-Pb and whole rock Rb-Sr isochronal age show Xiongmei Cu-bearing granodiorite porphyry formed during 110–105 Ma. The zircon Hf isotope together with whole rock Sr-Nd isotopic features and high Mg# value (39–59), relatively high Cr (10.9–35.5 ppm) and Ni (10–224 ppm), indicating a melt deriving from mixing between mantle material and an ancient crustal source. The possibility of crustal addition in the magma is further supported by varied Eu anomalies (0.5–1.5), Sr anomalies (0.6–1.9) and high Al2O3 contents (15.50–17.25 wt%). Geochemical composition including K2O contents (0.52–4.72 wt%) and K2O/Na2O ratios (0.2–5.5), and the linear relations between LOI, Cu, Rb and Sr contents indicated that the magma sourced from melting of an amphibolite source, and further suggesting that the juvenile crust derived from an enriched lithospheric mantle. The ratios between incompatible elements together with the absence of Ce anomaly suggested the contribution of fluids from subducted oceanic crust rather than melt. The negative Eu and Sr anomaly features together with relatively high HREEs and Y contents, low (La/Yb)N and Sr/Y ratios are interpreted as low pressure partial melting. Combination with the regional geologic background, we adopted a slab break-off model to explains the diverse contemporaneous magmatic rocks recognized in the North Lhasa subterrane including that of the Xiongmei Cu-bearing granodiorite porphyry.

Origin and tectonic significance of the Hoboksar ophiolitic mélange in northern West Junggar (NW China)

Year: 2019
Products: UP213;New Wave;
Authors: Du, H;Chen, J;Ma, X;Han, B;Liu, B;Simon, A;Liu, J;Ren, R;Li, C;Zhou, L;Lei, Z;
Journal: Lithos

Although the Early Paleozoic tectonic framework of northern West Junggar is essential for understanding accretionary processes in the southwestern Central Asian Orogenic Belt, this setting is still not well understood. In order to address this issue, we employed detailed geochronological, geochemical and Sr-Nd-Hf-Os isotope analyses on the Hoboksar ophiolitic mélange in northern West Junggar. The Hoboksar ophiolitic mélange mainly consists of serpentinized peridotites, pyroxenites, gabbros, diabase, cherts, marbles, volcanic and pyroclastic rocks. It is characterized by a “block-in-matrix” structure with serpentinized peridotites as the matrix which is crosscut by later diorite porphyry and rhyolitic porphyry. Olivines and spinels in these serpentinized peridotites show high Fo# and Cr#, respectively. The clinopyroxenes in the pyroxenites exhibit high Mg#, low Al2O3 and Cr2O3. The serpentinized peridotites have extremely low rare-earth element (REE) abundances, U-shaped to flat REE patterns and positive Eu anomalies. Their particularly low Re/Os, initial 187Os/188Os and γOs(t) imply that they could represent residual phases after partial melting of upper mantle. The gabbros and diabases display slight fractionation between light REE and heavy REE, negligible Eu anomalies, depletion in Rb, Nb and Ta, enrichment in Th and U, low initial 87Sr/86Sr and positive εNd(t). The mineral and whole-rock geochemical and isotopic compositions of these ultramafic-mafic rocks demonstrate that the Hoboksar ophiolitic mélange originated from a depleted mantle in a fore-arc supra-subduction zone (SSZ) setting.

The Lower Paleozoic Plutonic-Volcanic connection in the Eastern Magmatic Belt, SW Gondwana, northern Puna Argentina

Year: 2019
Products: UP213;New Wave;
Authors: Ortiz, A;Quiroga, M;Becchio, R;Hauser, N;
Journal: Journal of South American Earth Sciences

The relationship between plutonic and volcanic rocks is key to understanding the geochemical evolution of silicic magma systems. In order to untangle the plutonic and volcanic connection and contribute to the reconstruction of the Lower Paleozoic Arc at the SW Gondwana margin, in this study we describe the Sey Plutonic-Volcanic Unit, located in Eastern Magmatic Belt, northern Puna, Argentina. Additionally, we present zircon U-Pb ages by LA-MC-ICP-MS and geochemical data. The studied unit is comprised of monzogranites, granodiorites, gabbros, dacites, and rhyodacites, cropping out as plutonic bodies, laccoliths, sills, subaqueous domes, and lava flows. Following the analyses of the different zircon age populations, the granodiorites bodies crystallized at ∼480 Ma, the monzogranites followed at ∼470 Ma. Lastly, the rhyodacites crystallized at ∼446 Ma. Afterward the age groups analyses, in the Eastern Magmatic Belt, northern Puna, the magmatic activity started from ∼520 to 515 Ma until ∼446 Ma, with the magmatic activity peak at ∼485-475 Ma. The age groups, besides with the geochemistry data, isotope, and magma source similarities of the Eastern Magmatic Belt, both north and southern Puna, underline that the formation of the granitoids and volcanites in the Eastern Magmatic Belt was perhaps through a long-lived magmatic event, represented by low and high volume magmatic episodes.

Adakites without a slab: Remelting of hydrous basalt in the crust and shallow mantle of Borneo to produce the Miocene Sintang Suite and Bau Suite magmatism of West Sarawak

Year: 2019
Products: NWR213;New Wave;
Authors: Breitfeld, H;Macpherson, C;Hall, R;Thirlwall, M;Ottley, C;Hennig-Breitfeld, J;
Journal: Lithos

We present new geochronological and geochemical data for Neogene magmatism from West Sarawak. Zircon U-Pb geochronology divides Neogene magmatic rocks of West Sarawak into a Lower Miocene West Sarawak Sintang Suite with ages of c. 19 to 21 Ma, and a Middle Miocene Bau Suite with ages of c. 12 to 14 Ma. Magmatism occurred in multiple short-lived pulses from approximately 24 Ma and was coeval with magmatic activity in NW Kalimantan and East Kalimantan. The majority of, but not all, Bau Suite samples display adakitic chemistry, while the West Sarawak Sintang Suite is predominantly non-adakitic. There was no active subduction zone or subducted slab associated with this adakitic magmatism. Instead, the geochemical diversity is consistent with the Bau and West Sarawak Sintang suites representing mixtures of mafic, mantle-derived magma with felsic magma derived from remelting of hydrous, mafic rock that had been emplaced into the lithosphere of Borneo as arc basalt tens or hundreds of millions of years previously. This origin is most evident in the main Sintang Suite of central Borneo (Kalimantan) which has preserved less contaminated examples of the mafic endmember. This endmember resembles basaltic rocks from several locations across Borneo suggesting that intraplate, mantle-derived magmatism was responsible for remelting older, hydrated basaltic rocks in the crust.

Archaeometric characterization of prehistoric pottery from Baħrija, Malta

Year: 2019
Products: New Wave;New Wave Research;
Authors: Tanasi, D;Brunelli, D;Cannavò, V;Levi, S;
Journal: Journal of Archaeological Science: Reports

The end of prehistory in the Maltese archipelago is characterized by the production of a problematic class of pottery, until now attested just at the site of Baħrija, on the western coast of Malta. Such a production represents a break with the tradition in terms of repertoire of shapes, style and technology and it has been interpreted as the result of contact between locals and foreign immigrants. The recent overall reappraisal of the unpublished ceramic assemblage collected during the excavations carried out at Baħrija, represents a unique opportunity to focus on the technological aspects of the production, trying to shed light on the issue of the break with the tradition and the impact of external influxes. Petrographic analysis on thin sections and chemical analyses via X-ray fluorescence spectroscopy (XRF) and laser ablation-inductively coupled plasma mass spectroscopy (LA-ICP-MS) have been carried out to characterize the Baħrija pottery production in order to interpret from a different angle the issue of the possible arrival of newcomers and establishment of a foreign enclave in Malta, which until now has been hypothesized only on the basis of the sudden emergence of the Baħrija pottery.

Zircon U-Pb age and Nd isotope geochemistry of latest Neoproterozoic to early Paleozoic Oeyama ophiolite: Evidence for oldest MORB-type oceanic crust in Japanese accretionary system and its tectonic implications

Year: 2019
Products: UP213;New Wave;New Wave Research;
Authors: Kimura, K;Hayasaka, Y;
Journal: Lithos

The Oeyama ophiolite is considered as one of the major ophiolites in the Japanese Islands that forms a part of the “circum-Pacific Phanerozoic multiple ophiolite Belts”. In this study, zircon U-Pb age and their REE geochemistry, and Nd-Sr isotope geochemistry are presented for the gabbroic rocks of the Oeyama ophiolite to determine the precise crystallization age and characterize the proper tectonic setting of this ancient oceanic crust. The zircon grains of the two studied gabbroic samples yield 206Pb/238U ages of 545.4 ± 2.6 Ma and 532.4 ± 3.1 Ma. From five gabbroic rocks, a comparable 566 ± 95 Ma Sm-Nd whole rock isochron age is obtained. The time-corrected εtNd values (t = 545 Ma) for each sample are ranging from +7.2 to +7.7 that suggest their normal mid-oceanic basalt (N-MORB) affinity. Discrimination diagrams using zircon U/Yb versus Hf and Y also indicate their oceanic crustal origin. This is so far known the oldest date of ophiolite in the Japanese accretionary system. On the basis of the present dataset, we have offered a scenario of the potential tectonic development highlighting the journey of this group of oceanic crustal rocks from the mid-oceanic region till their final accretion to the Japanese Islands. The present tectonic model envisages an initial oceanward subduction at ca. 530 Ma switched over to the present continentward subduction at ca. 400 Ma. Moreover, the three different units of the Oeyama ophiolite have been re-classified based on the present age dataset, and the formation and evolution of these units constituting the typical lower part of the ocean plate are explained.

Simultaneous imaging of latent fingermarks and detection of analytes of forensic relevance by laser ablation direct analysis in real time imaging-mass spectrometry (LADI-MS)

Year: 2019
Products: NWR213;
Authors: Fowble, K;Musah, R;
Journal: Forensic Chemistry

Traditional analysis of latent fingermarks using dusting powders and cyanoacrylate fuming uncovers only the physical pattern of the fingerprint ridges, neglecting vast amounts of chemical information within the residue that could divulge more about the owner. Imaging mass spectrometry provides a means to retain the fingerprint ridge detail for identification while also revealing additional chemical information. The technique laser ablation direct analysis in real time imaging-mass spectrometry (LADI-MS) was applied to image the spatial distributions of small molecules of potential forensic relevance in latent fingermarks on non-conductive surfaces. By using this approach, no solvent, matrix, or high-vacuum conditions were required. An index finger was exposed to cocaine, psychoactive “legal high” plant material, pseudoephedrine, or the explosive RDX, and a fingermark was subsequently deposited on a glass slide for analysis. LADI-MS revealed the spatial distribution of endogenous cholesterol (localized to fingerprint ridges) and simultaneously detected the psychoactive small molecules cocaine, yangonin (derived from Piper methysticum), pseudoephedrine and the explosive RDX in latent fingermarks. The spatial distribution mapping of cholesterol in a lifted print on the non-conductive adhesive side of tape was also accomplished. The ion images of endogenous compounds and detection of exogenous molecules reveal details of chemical exposures, while connecting the exposure to the owner of the print.

Late Neoarchean slab rollback in the Jiaoliao microblock, North China Craton: Constraints from zircon U-Pb geochronology and geochemistry of the Yishui Complex, Western Shandong Province

Year: 2019
Products: NewWave;
Authors: Yu, Y;Li, D;Chen, Y;Song, L;Kang, H;Geng, J;
Journal: Lithos

Earth's plate tectonic system was initiated between 3.0 and 2.5 Ga and became the dominant regime for crustal growth and differentiation. However, it is unclear whether subduction–accretion processes, including slab rollback, occurred regionally in the area of the western Shandong Province Granite–Greenstone Terrane of the North China Craton (NCC) during the early development of plate tectonics. We quantified petrology, whole-rock geochemistry, and zircon U–Pb–Hf isotopes for felsic, mafic, and ultramafic rocks from the Yishui Complex (YC) in the NCC to constrain the origin of these rocks and the associated tectonic setting(s). The granites yield 207Pb/206Pb ages of 2509 ± 20 to 2484 ± 26 Ma, and magmatic zircon grains from these rocks have εHf(t) values of 0.6–6.4. The coeval mafic–dioritic rocks represent the fractional crystallization products of a primary magma that was derived from low-degree (<7%) partial melting of a metasomatized mantle source. The granodiorites were derived from the partial melting of oceanic slab material, with slab melts being contaminated by mantle wedge material during their ascent. The high-K granites represent the crustal reworking products of regional tonalite–trondhjemite–granodiorite and sedimentary rocks. Late Neoarchean magmatism in the YC was related to slab subduction, and slab rollback at ~2.50 Ga led to the generation of potassic rocks, coeval mafic–ultramafic xenoliths, and granulite metamorphism with a counterclockwise P–T–t path in the Yishui area.

Mobilisation of arsenic, selenium and uranium from Carboniferous black shales in west Ireland

Year: 2019
Products: UP213;New Wave;
Authors: Armstrong, JGT;Parnell, J;Bullock, LA;Boyce, AJ;
Journal: Applied Geochemistry

The fixation and accumulation of critical elements in the near surface environment is an important factor in understanding elemental cycling through the crust, both for exploration of new resources and environmental management strategies. Carbonaceous black shales are commonly rich in trace elements relative to global crustal averages, many of which have potential environmental impacts depending on their speciation and mobility at surface. This trace element mobility can be investigated by studying the secondary mineralisation (regolith) associated with black shales at surface. In this study, Carboniferous shales on the west coast of Ireland are found to have higher than average shale concentrations of As, Cd, Cu, Co, Mo, Ni, Se, Te and U, similar to the laterally equivalent Bowland Shales, UK. Groundwater penetration and oxidative weathering of these pyritic black shales produces oxide deposits, dominated by goethite and jarosite, which are significantly enriched in As (44–468 ppm), Se (12–184 ppm), U (6–158 ppm) and other trace elements, compared to concentrations in the parent shales. Major elemental abundances vary in composition from 3.5 to 29.4% sulphate, 0.6–9.1% phosphate and 36.6–47.2% iron-oxide. Phosphate substitution within jarosite is observed in these samples, formed under ambient pressure and temperature conditions.

Quantitative analysis of plant leaf elements using the LA-ICP-MS technique

Year: 2019
Products: UP213;New Wave;
Authors: Pedrosa Diniz, A;Rodrigues Kozovits, A;de Carvalho Lana, C;Trópia de Abreu, A;Garcia Praça Leite, M;
Journal: International Journal of Mass Spectrometry

The use of Laser Ablation coupled to Mass Spectrometry is a promising technique for analysis of plant tissue elements because it has advantages over conventional digestion techniques such as reduced levels of contamination and sample preparation time, possibility of spatial distribution analysis of elements, high number of repetitions, among others. This technique still has some limitations, especially with regard to calibration, which may result in inaccurate chemical analyses. The present study aims to compare two types of analyzers (quadrupole and magnetic sector field) regarding precision and accuracy. Certified material was examined, and also plant material analyzed by both solution in inductively coupled plasma optical emission spectrometry (ICP OES) and by laser ablation methods. It was observed that the magnetic sector field analyzer gave better results in relation to precision (relative standard deviation - RSD) and accuracy (recovery). An elemental composition pattern similar to that of the sample to be analyzed is relevant to validate the methodology for the analysis of leaves collected under different environmental conditions. Thus, pulverized Eremanthus erytropappus leaves were suggested as a second type of validation standard to be used in analyzes of plants belonging to the Atlantic and Cerrado Forest biomes.

Petrogenesis of A-type granites associated with Sn–Nb–Zn mineralization in Ririwai complex, north-Central Nigeria: Constraints from whole-rock Sm Nd and zircon Lu Hf isotope systematics

Year: 2019
Products: NWR193;ESI;
Authors: Girei, M;Li, H;Algeo, T;Bonin, B;Ogunleye, P;Bute, S;Ahmed, H;
Journal: Lithos

We report a combined study of whole-rock major- and trace-element geochemistry, Sm Nd isotope composition, zircon U/Pb dating, and Lu Hf systematics of peralkaline and aluminous A-type granites from the Ririwai Ring Complex in north-central Nigeria. The Ririwai peralkaline and aluminous A-type granites are strongly ferroan, alkalic to alkali-calcic, and enriched in Hf, Zr, Ga, Rb, Y and REEs. They were emplaced between 176 ± 2.3 Ma and 169.6 ± 0.75 Ma. The peralkaline granites yield relatively higher ɛNd(t) (−2.3 to −1.2) and zircon ɛHf(t) values (−5.8 to −1.7) than the aluminous granites (ɛNd(t) = −3.6 to −3.3; zircon ɛHf(t) = −7.8 to −2.4). In addition, inherited zircons in the aluminous granites yield Pan-African (~590 Ma) ages and low ɛHf(t) values (−14.0). Taken together, these data suggest that the granites formed from extensive fractional crystallization of a transitional basaltic melt derived from an enriched OIB mantle source. The depletions of MgO, CaO, Ti2O, Sr and Ba in the granites indicate that Mg-rich olivine, calcic pyroxene, calcic amphibole, feldspars and Fe Ti oxides were the major fractionated phases during magma evolution. In addition, several types of evidence, e.g., moderately negative ɛNd(t) and ɛHf(t) values, and the presence of inherited zircons, imply that the parental melt was modified by assimilation of Pan-African upper crust into which the granites were emplaced. A transtensional regime generated prior to late Jurassic breakup of Gondwana, which led to reactivation of shear zones and opening of associated transcurrent faults, paved the way for emplacement of the A-type suite. The Sn–Nb–Zn mineralization of the Ririwai A-type suite was probably linked to complex magmatic evolutionary processes involving extensive fractional crystallization coupled with crustal assimilation and late-stage hydrothermal fluid activity.

Zircon U-PB ages and geochemical characteristics of the Pana Formation volcanic rocks from the Linzizong Group in Zhaxue area, eastern Gangdese belt, Xizang (Tibet), and its tectonic significance (西藏冈底斯东段扎雪地区林子宗群帕那组火山岩锆石 U⁃ Pb 年龄, 地球化学特征及其构造意义)

Year: 2019
Products: NWR193;
Authors: Lui Fujun; Qin Song; Sun Chuanmin (刘, 富;秦, 松;孙, 传;)
Journal: Geological Review (地质论评)

Objectives: Than Pana Formation volcanic rocks of the Linzizong group are widely distributed in the Zhaxue area, eastern Gangdese belt, which is an important object to understand the geological evolution of the Gangdese belt. Methods: In this study, we report the results of the whole-rock geochemistry, zircon U-PB age and Lu-Hf isotopic composition date for the Pana Formation volcanic rocks in the Zhaxue area to constrain their emplacement ages, petrogenesis and tectonic significance. (内容提要: 本文对扎雪地区林子宗群帕那组火山岩进行主微量地球化学和锆石 U—Pb—Hf 同位素研究,以探 讨其形成时代、岩石成因及其构造意义。 锆石 U⁃Pb 年龄表明,扎雪地区帕那组火山岩形成于~52 Ma,与冈底斯东段 帕那组火山岩形成时代相似,暗示了帕那组在时空上具有相对一致的活动时限。 研究区火山岩高硅、富钠、富碱,A/ CNK 值为 130~ 1 73,属于过铝质钾玄岩系列。 同时,这些火山岩富集大离子亲石元素和轻稀土元素,亏损高场强 元素,有岛弧岩浆的亲属性,且其低 Mg # (1977~ 3896)及低含量的 Cr(3 00~ 343 μg/g)、Ni(2 90 ~ 15 6 μg/g)、Co (2 20~ 958 μg/g),La/Sm 值随 La 含量升高而无明显变化,表明这些火山岩在成岩过程中经历了明显的分离结晶 作用。 此外,扎雪地区帕那组火山岩锆石 εHf( t)平均值 -44 ~ -3 6,表明该火山岩起源于新生地壳物质的部分熔 融,有古老壳源物质加入源区中,形成了相对富集的 Hf 同位素特征。 结合前人在林周盆地及邻区的研究结果,表明 冈底斯东段林子宗群火山岩母岩浆随时间由岛弧环境的亏损地幔源区向碰撞环境壳源物质加入相对富集型源区的 转变,指示其形成环境经历了由岛弧向陆陆碰撞的转变;帕那组火山岩形成于印度板块与欧亚板块碰撞的初期阶 段,是记录这种体制转换的主要载体。)

Insights on the origin of the Graciosa A-type granites and syenites (Southern Brazil) from zircon U-Pb geochronology, chemistry, and Hf and O isotope compositions

Year: 2019
Products: New Wave;New Wave Research;
Authors: Vilalva, F;Simonetti, A;Vlach, S;
Journal: Lithos

The Neoproterozoic, post-collisional, Graciosa Province (southern Brazil) comprises several A-type intrusions and related volcanics of alkaline and subalkaline (or aluminous) petrographic associations. U-Pb age determinations, trace element, and Hf and O isotopic compositions were obtained for zircons from six distinct A-type granitic and syenitic plutons from both alkaline and subalkaline associations from the province. Geochronological results indicate that their emplacement, petrogenetic evolution and crystallization spanned over a ~9 million years interval, with peak magmatism at ~580 Ma. Plutons were emplaced in a post-collisional extensional regime related to the geodynamic evolution of the south-southeastern part of the Gondwana supercontinent. Hf isotopic compositions are highly variable, with εHf(t) values between +1.4 to −31, whereas δ18O signatures are mainly between +4.7 and +6.0‰. These features, along with trace element signatures, especially for Hf, U, Nb, and rare-earth elements, suggest that generation of the Graciosa rocks occurred via partial melting of a lithospheric mantle previously metasomatized by slab-derived fluids, followed by variable degrees of crustal contamination at depth.

Anomalous Fluid Inclusions in Gypsum and The Messinian Salinity Crisis

Year: 2019
Products: NWR193;ESI;
Authors: Doyle III, EW;
Journal: Thesis

Large amplitude environmental changes which developed at the end of the Miocene caused glacial stage TG32 at ~ 6 Ma and a substantial decrease in eustatic sea level (Manzi et al., 2013). This isolated the Mediterranean Sea from the Atlantic Ocean and gave rise to the Messinian Salinity Crisis (Manzi et al., 2012). During this geologic event, the Mediterranean was transformed from a small ocean into a giant evaporitic brine-pool in which more than one million cubic kilometers of salt accumulated over the course of ~700 ka (6-5.3 Ma) (Krijgsman et al., 1999). The brevity of such an extraordinary event has fascinated the scientific community for almost 50 years as the causes of and mechanisms by which such a large scale desiccation event can occur so rapidly lack any modern analogs (Roveri et al., 2014). The concept of the Messinian salinity crisis was first postulated from onshore studies of outcrops conducted in the 1950s which demonstrated the widespread, coeval development of hyper- and hyposaline environments around the Mediterranean at the end of the Miocene (Selli, 1954). However, the true scale and significance of these environmental changes in the Mediterranean were only realized after marine geology studies were carried out in 1970 by the Deep Sea Drilling Project (DSDP) Cruise Leg VIII. This expedition drilled a host of cores in the Mediterranean basin and discovered a reflective layer of evaporites, composed of gypsum and halite, 2-3 km thick, lying 100-200 m below the seafloor (Hsu et al., 1973).

Origin and duration of late orogenic magmatism in the foreland of the Variscan belt (Lesponne — Chiroulet — Neouvielle area, French Pyrenees)

Year: 2019
Products: NWR193UC;ESI;
Authors: Lemirre, B;Cochelin, B;Duchene, S;de Saint Blanquat, M;Poujol, M;
Journal: Lithos

During the late stage of the Variscan orogeny, the pyrenean segment underwent intense magmatism and regional high temperature – low pressure metamorphism. In the Lesponne – Chiroulet – Neouvielle area, a granodioritic pluton was emplaced in the upper crust while dioritic to granitic magmas were emplaced in metamorphic domes. Magmatism was contemporaneous with the regional crustal partial melting recorded in the core of the domes. The area is therefore a key target in the Pyrenees to discuss potential magmatic sources as well as the age and duration of the late Variscan magmatism. Geochemical data on representative magmatic rocks highlight two distinct sources of magma: a mantle source and a metasedimentary crustal source that produced respectively metaluminous and peraluminous magmas. Geochronological results show that magmatism took place over a period of about 10 My from ca. 303 to ca. 290 Ma. During this period, the middle to lower crust was composed of partially molten metasediments intruded by mantle and crustal magmas that crystallized in a final pulse at ca. 290 Ma. Late Variscan metamorphism and magmatism recorded in the Pyrenees have to be related to a significant and rapid heating from the underlying mantle rather than to crustal processes such as the maturation of a thickened continental crust. We propose that the initiation of metamorphism and bimodal magmatism at ca. 305 Ma in the Pyrenees is the expression of the delamination of the Gondwanan lithospheric mantle at a global scale in the Variscan belt.

Nature and timing of metamorphism within the San Isabel granite aureole, Wet Mountains, south Colorado

Year: 2019
Products: NWR193;ESI;TwoVol2;
Authors: Palmer, Z;
Journal: Thesis

The Wet Mountains, southern Colorado, expose Mesoproterozoic metamorphic and magmatic rocks that record the early deformational history of the east-central continental USA. An increase in metamorphic grade from northwest to southeast indicates that these lithologies represent an exposed cross-section through a tilted crustal block. Of particular interest to the geological history of the region are Cu- and Zn-bearing metamorphic rocks adjacent to the San Isabel A-type granite, situated in the southern Wet Mountains. Previous studies of these units have focused on the timing of base metal mineralization, although the pressure–temperature (P–T) conditions of equilibration and age (t) of metamorphism are unknown. Conventional thermobarometry and phase diagram-based thermodynamic modeling of metapelitic and metacarbonate rocks indicates P–T conditions of metamorphism within the upper amphibolite facies (~700 °C) at middle-crustal pressures (~6 kbar). These data implies a geothermal gradient of ~30–35 °C/km, which is typical of metamorphism in the core of a deforming orogen, although they mostly lack the foliated microstructures that often characterize regionally metamorphosed lithologies. In-situ U–Pb geochronology of monazite within sapphirine-bearing metasediments and garnet-biotite schist indicate that peak P–T conditions were reached at c. 1.36–1.34 Ga. These units are slightly younger than nearby lithologies situated outside of the thermal aureole (c. 1.43–1.39 Ga), but approximately the same age as the intrusion itself (c. 1.37–1.36 Ga). These rocks are thus interpreted to be of contact metamorphic origin, in contrast to those found elsewhere in the Wet Mountains, which do display prominent foliations and ductile deformation features indicative of regional metamorphism. However, as the temperature of emplacement and crystallization of the San Isabel granite is unlikely to have exceeded ~800–850 °C, these rocks document an unusual occurrence of normally granulite-facies and (ultra)high-temperature metamorphic minerals (e.g. sapphirine, corundum, orthopyroxene, and spinel) stabilizing at lower grade, potentially due to substitution of minor elements. Thus, caution must be used when using such parageneses as field indicators of geodynamic settings associated with extreme heat flow, such as continental rifting and/or voluminous emplacement of dry, mafic magma.

Two‐stage Variscan metamorphism in the Canigou massif: evidence for crustal thickening in the Pyrenees

Year: 2019
Products: NWR193UC;ESI;
Authors: Hoÿm de Marien, L;Le Bayon, B;Pitra, P;Van Den Driessche, J;Poujol, M;Cagnard, F;
Journal: J Metamorph Geol

The Variscan metamorphism in the Pyrenees is dominantly of the low-pressure-high-temperature (LP-HT) type. The relics of an earlier, Barrovian-type, metamorphism that could be related to orogenic crustal thickening are unclear and insufficiently constrained. A microstructural and petrological study of micaschists underlying an Ordovician augen orthogneiss in the core of the Canigou massif (Eastern Pyrenees, France) reveal the presence of two syntectonic metamorphic stages characterized by the crystallization of staurolite (M1) and andalusite (M2), respectively. Garnet is stable during the two metamorphic stages with a period of resorption between M1 and M2. The metamorphic assemblages M1 and M2 record similar peak temperatures of 580 °C at different pressure conditions of 5.5 kbar and 3 kbar, respectively. Using chemical zoning of garnet and calculated P–T pseudosections, a prograde P–T path is constrained with a peak pressure at ~6.5 kbar and 550 °C. This P–T path, syntectonic with respect to the first foliation S1, corresponds to a cold gradient (of ~9 °C/km), suggestive of crustal thickening. Resorption of garnet between M1 and M2 can be interpreted either in terms of a simple clockwise P–T path or a polymetamorphic two stage evolution. We argue in favour of the latter, where the medium‐pressure (Barrovian) metamorphism is followed by a period of significant erosion and crustal thinning leading to decompression and cooling. Subsequent advection of heat, probably from the mantle, lead to a new increase in temperature, coeval with the development of the main regional fabric S2. LA‐ICP‐MS U‐Th‐Pb dating of monazite yields a well‐defined date at c. 300 Ma. Petrological evidence indicates that monazite crystallization took place close to the M1 peak‐pressure conditions. However, the similarity between this age and that of the extensive magmatic event well documented in the eastern Pyrenees suggests that it probably corresponds to the age of monazite recrystallization during the M2 LP–HT event.

Integrated experimental and thermodynamic modelling research for primary and recycling pyrometallurgy

Year: 2019
Products: NWR193;Electro Scientific Industries;
Authors: Jak, E;Hidayat, T;Prostakova, V;Shishin, D;Shevchenko, M;Hayes, PC;
Journal: Proceedings of EMC 2019

Chemically complex concentrates and feed streams are being treated in pyrometallurgical primary metal and recycling processes. Accurate phase equilibrium data and predictive tools are needed to be able to optimise the process conditions, charge compositions, and partitioning of minor elements between different process streams. An integrated experimental and thermodynamic modelling research program on the complex multi-component, multi-phase Cu2O-PbO-ZnO-Al2O3-CaO-MgO-FeOFe2O3-SiO2-S-(As-Bi-Ni-Sb-Sn-Ag-Au) system is under way to support a consortium of major metallurgical primary and recycling companies. The experimental technique involves high temperature equilibration in controlled gas atmospheres, rapid quenching and direct measurement of equilibrium phase compositions with micro-analytical techniques including Electron Probe X-ray Microanalysis and Laser Ablation ICP-MS. The thermodynamic databases include advanced models for liquid and solid solutions phases; process modelling is performed using the FactSage software package. An overview of recent research achievements and examples of their industrial application are given in the paper.

Fluid–rock interactions in the shallow Mariana forearc: carbon cycling and redox conditions

Year: 2019
Products: New Wave;
Authors: Albers, E;Bach, W;Klein, F;Menzies, C;Lucassen, F;Teagle, D;
Journal: Solid Earth

Few data exist that provide insight into processes affecting the long-term carbon cycle at shallow forearc depths. To better understand the mobilization of C in sediments and crust of the subducting slab, we investigated carbonate materials that originate from the subduction channel at the Mariana forearc (< 20 km) and were recovered during International Ocean Discovery Program Expedition 366. Calcium carbonates occur as vein precipitates within metavolcanic and metasedimentary clasts. The clasts represent portions of the subducting lithosphere, including ocean island basalt, that were altered at lower blueschist facies conditions and were subsequently transported to the forearc seafloor by serpentinite mud volcanism. Euhedral aragonite and calcite and the lack of deformation within the veins suggest carbonate formation in a stress-free environment after peak metamorphism affected their hosts. Intergrowth with barite and marked negative Ce anomalies in carbonate attest the precipitation within a generally oxic environment, that is an environment not controlled by serpentinization. Strontium and O isotopic compositions in carbonate (87Sr∕86Sr = 0.7052 to 0.7054, δ18OVSMOW = 20 to 24 ‰) imply precipitation from slab-derived fluids at temperatures between ∼130 and 300 ∘C. These temperature estimates are consistent with the presence of blueschist facies phases such as lawsonite coexisting with the carbonates in some veins. Incorporated C is inorganic (δ13CVPDB = −1 ‰ to +4 ‰) and likely derived from the decarbonation of calcareous sediment and/or oceanic crust. These findings provide evidence for the mobilization of C in the downgoing slab at depths of < 20 km. Our study shows for the first time in detail that a portion of this C forms carbonate precipitates in the subduction channel of an active convergent margin. This process may be an important asset in understanding the deep carbon cycle since it highlights that some C is lost from the subducting lithosphere before reaching greater depths.

Origin and evolution of the proterozoic granitoids of eastern Colombia, northwest of the Amazonian Craton (Origen y evolución de los granitoides proterozoicos del oriente colombiano, noroeste del Cratón Amazónico)

Year: 2019
Products: NWR193UC;ESI;
Authors: Bonilla Perez, A;
Journal: Thesis

The study area of this work are the Guainía and Vaupés departments in the eastern part of Colombia, near to Venezuela and Brazil, where the oldest rocks of Colombia are outcropping as northwestern part of the Amazonian Craton, actually largely covered by the Amazonian rain-forest. Unraveling the poorly understood geological characteristics and history of this extended region with unknown mineral deposits was a great motivation for this study. Both stratigraphic and structural knowledge about the main unit described as Mitu Complex is limited, and especially reconstructing the origin and evolution of the magmatic rocks in this part of the Amazonian Craton is challenging and may enhance future exploratory works. This doctoral thesis is within the modality of compendium of publications, it is composed of 6 chapters of which 5 correspond to articles (2 published).The research process passed through three stages: a) bibliographic compilation, logistic planning and field work; b) samples preparation and laboratory analysis and c) interpretation in combination with verification of results in the field. Only by means of river expeditions and complicated field work in difficult-to access areas, geological reconnaissance and detailed description of each observed outcrop as well as sampling of rocks with textural and compositional variations, was possible. The material processed for mineralogical, geochemical and geochronological analysis, allowed to characterize different metamorphic, magmatic and sedimentary Proterozoic events.

Tailored and deep porosification of LTCC substrates with phosphoric acid

Year: 2019
Products: NWR213;ESI;
Authors: Hajian, A;Smetaczek, S;Zellner, C;Stöger-Pollach, M;Konegger, T;Limbeck, A;Schmid, U;
Journal: Journal of the European Ceramic Society

Low temperature co-fired ceramics (LTCC) as an advanced technology for robust assembly of electronic components, has attracted significant attention in a wide application range such as in wireless communication or automotive radar systems. However, accurate designs of micromachined devices operated at high frequencies require substrates with regions of tailored permittivities. Introduction of controlled porosity into the substrate via wet-chemical etching procedure, is a promising approach for permittivity reduction which can be applied to commercially available LTCC without necessitating to alter their composition or sintering process. In the present study, by selective dissolution of celsian phase a very deep porosification (highest reported so far) could be realized while preserving the surface quality. Also, by a careful selection of the etching parameters, the depth of porosification and hence the permittivity reduction can be delicately tailored. Laser ablation inductively coupled plasma mass spectrometry was used for the investigation of chemical compositions of substrates.

Metal fluxes during magmatic degassing in the oceanic crust: sulfide mineralisation at ODP site 786B, Izu-Bonin forearc

Year: 2019
Products: NWR213;
Authors: Patten, C;Pitcairn, I;Alt, J;Zack, T;Lahaye, Y;Teagle, D;Markdahl, K;
Journal: Miner Deposita

Volcanogenic massive sulfide deposits are enriched in metals that are either derived from hydrothermal alteration of the basement rocks or supplied by exsolution of metal-rich volatiles during magmatic differentiation. The extent to which each process contributes to metal enrichment in these deposits varies between different tectonic settings. Ocean Drilling Program Hole 786B recovered > 800 m of upper oceanic crust from a supra-subduction zone setting and includes a 30-m-thick mineralised zone. In situ S isotopic compositions of pyrite decrease from 5.9 ± 2.9‰ in the upper mineralised zone down to − 3.3 ± 2.1‰ in the extensively altered central mineralisation zone, potentially indicating strong magmatic fluid input in this area. Whole rock data and in situ trace element analyses in sulfide minerals show enrichment of Ag, As, Au, Bi, Mo, S, Se, Sb and Te in the mineralised zone. Evaluation of metal behaviour during magmatic differentiation and primary metal fertility of basement rocks suggests that degassing melt is the main source for the high Au, Se and S enrichment observed in the mineralised zone. Magmatic volatile exsolution occurred late during the magmatic differentiation (~ 2 wt.% MgO), concomitant with oxide crystallisation and metal depletion in the melt. Comparison of Ocean Drilling Program Hole 786B with volcanogenic massive sulfide deposits hosted by boninitic volcanic successions, such as in the Semail ophiolite, the Newfoundland Appalachians and the Flin Flon Belt, suggests that magmatic fluid exsolution could be a common mechanism for Au enrichment in bimodal mafic volcanogenic massive sulfide deposits.

Reconstruction of past climate variability during Marine Isotope Stage 3 and the Holocene using speleothems: Special emphasis on the application of the Sr isotope system

Year: 2019
Products: UP213;
Authors: Weber, M;
Journal: Thesis

Speleothems are increasingly used as palaeoclimate archives due to their potential to reveal climatic and environmental patterns for all continental areas and climate zones. They can be precisely dated using the U-series disequilibrium method, allowing for the constraint of independent age depth models for proxy records, such as δ 13C, δ18O and trace elements to reconstruct palaeoclimate variability. Additionally, Sr isotopes have been increasingly applied to speleothem samples in the recent years. The Sr isotope system is used to investigate hydrological processes in the karst, as well as differences in the weathering of soil components. Strontium isotopes have traditionally been analysed by thermal ionisation mass spectrometry (TIMS), which requires chemical separation of Sr using ion-chromatographic resins and suffer from long measurement times. Progressin laser ablation systems(LA) and multi-collector inductively plasma mass spectrometry (MC-ICP-MS) have recently allowed the combination of these two techniques to measure Sr isotopesin several materialsin-situ without any chemical separation. Furthermore, sample throughput is significantly increased with this method due to reduced analysis time. In the framework of this thesis, the LA-MC-ICP-MS technique was adapted for the Sr isotope analysis of speleothems. Since this technique has numerous potential applications besides speleothems, numerous carbonate and phosphate reference materials, as well as bioapatite samples were analysed. In order to improve the data availability of suitable reference materials, which are a basic requirement for reliable analyses, eight different reference materials have been analysed for Sr isotopes. Furthermore, a customised carbonate microanalytical reference material was characterised, improving the analytical precision and accuracy for further in-situ measurements of low-Sr carbonate samples, such as speleothems. The analysis of a unique speleothem sample from Bunker Cave (Bu2) demonstrates the potential of Sr isotopes in a multi-proxy palaeoclimate reconstruction. Stalagmite Bu2 revealed two distinctive growth phases during the early Marine Isotope Stage 3, which has been often argued to be too cold and dry to enable speleothem growth in Central Europe. Based on the analysis of stable isotopes, trace elements and Sr isotopes, we were able to show that Central Europe was in a warm and humid climate state during this time, allowing speleothems to grow and soil to form. In addition, we show that these two growth phases differed significantly from each other, with the early phase being much more humid. To evaluate the significance of a single stalagmite stable isotope record, four Holocene speleothem samples from the Hüttenbläserschachthöhle (HBSH) were analysed for stable isotopes, trace elements and Sr isotopes. The resulting dataset was compared to the nearby Bunker Cave and revealed significant differences in the stable isotope record. While similar trends were observed in the early Holocene in both cave systems, the most recent 7 – 6 ka revealed significant differences, especially in the δ13C record. Based on the additional analyses of trace elements and Sr isotopes, it was possible to attribute these differences to increased disequilibrium isotope fractionation in HBSH. Therefore, speleothem palaeoclimate records based on a single sample should be handled with care and a multi-proxy approach should be applied to enable trustworthy conclusions.

A new freeware tool for image processing and its application to high speed LA-ICP-MS imaging

Year: 2019
Products: NWRimage;Dual Concentric Injector;
Authors: Managh, A;Reid, P;
Journal: J. Anal. At. Spectrom.

A new standalone, non-commercial software application has been developed to enable rapid generation of images from laser ablation-inductively coupled plasma-mass spectrometry data. The software locates peaks within raw data files and uses the peak locations to segment the data at appropriate intervals, enabling conversion of the data into a matrix of colour coded pixels. The app was developed in order to process baseline separated peaks produced by the latest generation of low-dispersion laser ablation systems, but it is equally applicable to rastered imaging using alternative laser ablation platforms. The peak recognition feature also has applicability to single cell and single particle ICP-MS applications. The app was demonstrated for the imaging of zinc in a stained section of rat retina tissue at lateral resolutions down to 1 μm. Less than two minutes was required for conversion of the raw data into a 60 000 pixel image.

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