scholarly journals Extracting Reliable Paleo-Ocean Temperatures at Southern Mid-Latitudes During the Greenhouse to Icehouse Transition: a LA-ICP-MS Study of the Trace Element Chemistry of Eocene Foraminifera from New Zealand

2021 ◽  
Author(s):  
◽  
John Benjamin Creech
Keyword(s):  
New Zealand ◽  
Trace Element ◽  
Benthic Foraminifera ◽  
Inductively Coupled Plasma ◽  
Middle Eocene ◽  
Isotope Analysis ◽  
Time Interval ◽  
Northern Margin ◽  
Icp Ms ◽  
Fe And Mn

<p>Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been used to measure in situ elemental (Mg, Al, Mn, Zn, Sr, Ba/Ca) ratios of 13 species of variably preserved early to middle Eocene planktonic and benthic foraminifera from the mid-Waipara River section, north Canterbury, New Zealand. The sediments from Waipara River were deposited at bathyal depths (ca. 1000 m) on the northern margin of the east-facing Canterbury Basin at a paleo-latitude of ca. 55 dgrees S. LA-ICP-MS analysis yields trace element depth profiles through foraminifera test walls that can be used to identify and exclude zones of surficial contamination and infilling material resulting from diagenetic coatings, mineralisation and detrital sediment. Screened Mg/Ca ratios are used to calculate sea temperatures from late early to early middle Eocene (ca. 51 to 46.5 Ma), a time interval that appears to span the termination of the Early Eocene Climatic Optimum (EECO). During this time, sea surface temperatures (SST) varied from 30 to 24 degrees C and bottom water temperatures (BWT) from 21 to 14 degrees C. Comparison of Mg/Ca sea temperatures with published delta superscript 18 O and TEX subscript 86 temperature data from the same samples (Hollis et al., 2009) shows close correspondence, indicating that LA-ICP-MS can provide reliable Mg/Ca sea temperatures even where foraminiferal test preservation is less than ideal. Agreement between the three proxies also implies that Mg/Ca - temperature calibrations for modern planktonic and benthic foraminifera can generally be applied to Eocene species, although some species (e.g., V. marshalli) show significant calibration differences. The Mg/Ca ratio of the Eocene ocean is constrained by our data to be 35-50% lower than the modern ocean depending on which TEX86 - temperature calibration is used to compare with the Mg/Ca sea temperatures (Kim et al., 2008; Liu et al., 2009). Sea temperatures derived from oxygen isotope analysis of foraminifera from mid-Waipara show amplified variability relative to the Mg/Ca and TEX86 derived temperatures. While this difference might be attributed to the oxygen isotopes being more susceptible to diagenetic effects, the data may be consistent with the growth and collapse of significant global ice sheets during cool periods in the Eocene on timescales of ca. 0.5 Myr. The timing of the termination of the EECO in the reconstructed climate record from mid-Waipara is consistent with other published climate records (Tripati et al., 2003, 2005; Zachos et al., 2008).  A large decrease in foraminiferal Mn/Ca ratios up the mid-Waipara section is observed with the youngest samples having Mn/Ca ratios similar to modern foraminifera. This does not appear to be a diagenetic fingerprint as foraminiferal preservation is generally poorer up-section. Global cooling following the EECO may have led to enhanced biological productivity and uptake of Fe and Mn, thereafter producing an ocean with Mn concentrations more similar to the present ocean. This hypothesis is consistent with that proposed to explain changes in the thallium isotope ratios of Fe and Mn crusts observed at this time (Nielsen et al., 2009).</p>

Extracting Reliable Paleo-Ocean Temperatures at Southern Mid-Latitudes During the Greenhouse to Icehouse Transition: a LA-ICP-MS Study of the Trace Element Chemistry of Eocene Foraminifera from New Zealand

2021 ◽  
Author(s):  
◽  
John Benjamin Creech
Keyword(s):  
New Zealand ◽  
Trace Element ◽  
Benthic Foraminifera ◽  
Inductively Coupled Plasma ◽  
Middle Eocene ◽  
Isotope Analysis ◽  
Time Interval ◽  
Northern Margin ◽  
Icp Ms ◽  
Fe And Mn

<p>Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been used to measure in situ elemental (Mg, Al, Mn, Zn, Sr, Ba/Ca) ratios of 13 species of variably preserved early to middle Eocene planktonic and benthic foraminifera from the mid-Waipara River section, north Canterbury, New Zealand. The sediments from Waipara River were deposited at bathyal depths (ca. 1000 m) on the northern margin of the east-facing Canterbury Basin at a paleo-latitude of ca. 55 dgrees S. LA-ICP-MS analysis yields trace element depth profiles through foraminifera test walls that can be used to identify and exclude zones of surficial contamination and infilling material resulting from diagenetic coatings, mineralisation and detrital sediment. Screened Mg/Ca ratios are used to calculate sea temperatures from late early to early middle Eocene (ca. 51 to 46.5 Ma), a time interval that appears to span the termination of the Early Eocene Climatic Optimum (EECO). During this time, sea surface temperatures (SST) varied from 30 to 24 degrees C and bottom water temperatures (BWT) from 21 to 14 degrees C. Comparison of Mg/Ca sea temperatures with published delta superscript 18 O and TEX subscript 86 temperature data from the same samples (Hollis et al., 2009) shows close correspondence, indicating that LA-ICP-MS can provide reliable Mg/Ca sea temperatures even where foraminiferal test preservation is less than ideal. Agreement between the three proxies also implies that Mg/Ca - temperature calibrations for modern planktonic and benthic foraminifera can generally be applied to Eocene species, although some species (e.g., V. marshalli) show significant calibration differences. The Mg/Ca ratio of the Eocene ocean is constrained by our data to be 35-50% lower than the modern ocean depending on which TEX86 - temperature calibration is used to compare with the Mg/Ca sea temperatures (Kim et al., 2008; Liu et al., 2009). Sea temperatures derived from oxygen isotope analysis of foraminifera from mid-Waipara show amplified variability relative to the Mg/Ca and TEX86 derived temperatures. While this difference might be attributed to the oxygen isotopes being more susceptible to diagenetic effects, the data may be consistent with the growth and collapse of significant global ice sheets during cool periods in the Eocene on timescales of ca. 0.5 Myr. The timing of the termination of the EECO in the reconstructed climate record from mid-Waipara is consistent with other published climate records (Tripati et al., 2003, 2005; Zachos et al., 2008).  A large decrease in foraminiferal Mn/Ca ratios up the mid-Waipara section is observed with the youngest samples having Mn/Ca ratios similar to modern foraminifera. This does not appear to be a diagenetic fingerprint as foraminiferal preservation is generally poorer up-section. Global cooling following the EECO may have led to enhanced biological productivity and uptake of Fe and Mn, thereafter producing an ocean with Mn concentrations more similar to the present ocean. This hypothesis is consistent with that proposed to explain changes in the thallium isotope ratios of Fe and Mn crusts observed at this time (Nielsen et al., 2009).</p>

Paleoredox conditions, hydrothermal history, and target vectoring in the Macmillan Pass base-metal district, Yukon, Canada: 2 – Pyrite paragenesis and mineral chemistry

2021 ◽  
Vol 59 (5) ◽  
pp. 1233-1259
Author(s):  
Claire Leighton ◽  
Daniel Layton-Matthews ◽  
Jan M. Peter ◽  
Michael G. Gadd ◽  
Alexandre Voinot ◽  
...  
Keyword(s):  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Mineral Chemistry ◽  
Hydrothermal Activity ◽  
Unconsolidated Sediments ◽  
Lateral Migration ◽  
Sulfide Mineralization ◽  
Ambient Seawater ◽  
Clastic Sediment ◽  
Icp Ms

ABSTRACT The MacMillan Pass district in Yukon, Canada, hosts the Tom and Jason clastic sediment-hosted Zn-Pb-Ag-(Ba) deposits. Pyrite-bearing drill core samples were collected from seven drill holes that intersected sulfide mineralization and time-stratigraphically equivalent rocks at varied spatial distances extending up to 3 km away from the deposits to assess the relative timing of pyrite mineralization and the chemistry of pyrite paragenesis. There are four pyrite morphologies: framboids and polyframboids (Py1), subhedral to euhedral inclusion-free crystals (Py2a), silicate inclusion-bearing nodules with serrated edges (Py2b), and euhedral idiomorphic overgrowths on preexisting pyrite morphologies (Py3). These morphological varieties correspond in time from syngenetic to earliest diagenetic growth (Py1), early to late diagenetic growth (Py2a, Py2b), and metamorphic crystallization and/or recrystallization of previous textural varieties (Py3). A representative subset of pyrite grains was analyzed for trace element contents and distributions by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Analyses by LA-ICP-MS reveal that each textural variety of pyrite has a distinct trace element composition that also varies depending on stratigraphic unit. A suite of clastic sediment-hosted sulfide mineralization-related elements was incorporated into Py2 within sulfide mineralized units at greater abundances than that in unmineralized units (e.g., Zn, As, Pb, Tl, Bi). Lead abundances and Pb/Se and As/Mo values in pyrite are the most robust vectoring tools documented. The timing for clastic sediment-hosted Zn-Pb mineralization was syn and/or post late diagenesis (Py2b). A Ba-enriched horizon was identified in rocks and this is interpreted to be the distal time-stratigraphic equivalent unit to Zn-Pb mineralization. The Ba-enriched horizon contains Py2 with anomalous metal (Tl, Co, Mn, Cd, Zn, Sb) contents and abundant macroscopic baryte, and it is interpreted to represent the distal expression of sulfide mineralization-forming hydrothermal activity. Four genetic models for mineralization are reviewed; however, the only model that is consistent with our whole rock and pyrite geochemistry involves venting of buoyant hydrothermal fluid, mixing with ambient seawater, and remaining or sinking into unconsolidated sediments, with lateral migration up to 2–3 km from the vent source.

High-precision analysis of potassium isotopes by MC-ICP-MS without collision cell using cool plasma technique in low resolution mode

2021 ◽  
Author(s):  
Hai-Ou Gu ◽  
Sun He
Keyword(s):  
High Precision ◽  
Inductively Coupled Plasma ◽  
Isotope Analysis ◽  
Collision Cell ◽  
Low Resolution ◽  
Inductively Coupled ◽  
Plasma Technique ◽  
Icp Ms ◽  
Cool Plasma ◽  
Plasma Mass Spectrometry

This study presents a method for high-precision stable potassium (K) isotope analysis using Multi-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS) without collision cell in low resolution mode. Cold plasma technique...

High-resolution LA-ICP-MS trace-element mapping of magmatic biotite: A new approach for studying syn- to post-magmatic evolution

2020 ◽  
Vol 58 (3) ◽  
pp. 293-311 ◽  
Author(s):  
Zeinab Azadbakht ◽  
David R. Lentz
Keyword(s):  
New Brunswick ◽  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Fluid Phase ◽  
New Approach ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Magma Crystallization ◽  
Topaz Granite

ABSTRACT Biotite grains from 22 felsic intrusions in New Brunswick were mapped in situ using a laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS). We investigated the extent to which biotite can retain its magmatic zoning patterns and, where zoning does exist, how it can be used to elucidate early to late stage, syn-magmatic to post-crystallization processes. Although the major element and halogen contents of the examined biotite phenocrysts are homogeneous, two-thirds of the grains display trace-element zoning for Ba, Rb, and Cs. The results also indicated that zoning is better retained in larger grains (i.e., &gt; 500 × 500 μm) with minimal alteration and mineral inclusions. An exceptionally well-zoned Li-rich siderophyllite from the Pleasant Ridge topaz granite in southwestern New Brunswick shows Ti, Ta, Sn, W, Cs, Rb, and V (without Li or Ba) zoning. Cesium values increase from 200 to 1400 ppm from core to rim. Conversely, Sn and W values decrease toward the rim (50 to 10 and 100 to 10 ppm, respectively). Tantalum and Ti values show fewer variations but drop abruptly close to the rim of the grain (100 to 20 and 2000 to 500 ppm, respectively). These observations may indicate crystallization of mineral phases with high partition coefficients for these highly incompatible elements (except Ti) (e.g., cassiterite and rutile) followed by fractionation of a fluid phase at a later stage of magma crystallization. The preservation of zoning may indicate rapid cooling post-crystallization of the parent magma.

scholarly journals Coupled Substitutions of Minor and Trace Elements in Co-Existing Sphalerite and Wurtzite

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 147 ◽  
Author(s):  
Allan Pring ◽  
Benjamin Wade ◽  
Aoife McFadden ◽  
Claire E. Lenehan ◽  
Nigel J. Cook
Keyword(s):  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Significant Variation ◽  
Inductively Coupled ◽  
Trace Element Chemistry ◽  
Icp Ms ◽  
Two Samples ◽  
Coupled Substitution ◽  
Plasma Mass Spectrometry ◽  
Growth Zoning

The nature of couple substitutions of minor and trace element chemistry of expitaxial intergrowths of wurtzite and sphalerite are reported. EPMA and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses display significant differences in the bulk chemistries of the two epitaxial intergrowth samples studied. The sample from the Animas-Chocaya Mine complex of Bolivia is Fe-rich with mean Fe levels of 4.8 wt% for wurztite-2H and 2.3 wt% for the sphalerite component, while the sample from Merelani Hills, Tanzania, is Mn-rich with mean Mn levels in wurztite-4H of 9.1 wt% and for the sphalerite component 7.9 wt% In both samples studied the wurtzite polytype is dominant over sphalerite. LA-ICP-MS line scans across the boundaries between the wurtzite and sphalerite domains within the two samples show significant variation in the trace element chemistries both between and within the two coexisting polytypes. In the Merelani Hills sample the Cu+ + Ga3+ = 2Zn2+ substitution holds across both the wurztite and sphalerite zones, but its levels range from around 1200 ppm of each of Cu and Ga to above 2000 ppm in the sphalerite region. The 2Ag+ + Sn4+ = 3Zn2+ coupled substitution does not occur in the material. In the Animas sample, the Cu+ + Ga3+ = 2Zn2+ substitution does not occur, but the 2(Ag,Cu)+ + Sn4+ = 3Zn2+ substitution holds across the sample despite the obvious growth zoning, although there is considerable variation in the Ag/Cu ratio, with Ag dominant over Cu at the base of the sample and Cu dominant at the top. The levels of 2(Ag,Cu)+ + Sn4+ = 3Zn2+ vary greatly across the sample from around 200 ppm to 8000 ppm Sn, but the higher values occur in the sphalerite bands.

Boron isotope analysis of coral skeletons by laser ablation MC-ICP-MS: new insights into calcification and environmental reconstruction at high temporal resolution

2020 ◽  
Author(s):  
Gavin L. Foster ◽  
Thomas B. Chalk ◽  
Christopher D. Standish
Keyword(s):  
Laser Ablation ◽  
Trace Element ◽  
Temporal Resolution ◽  
Isotope Analysis ◽  
Coral Skeleton ◽  
Boron Isotope ◽  
High Temporal Resolution ◽  
Carbonate System ◽  
Seawater Ph ◽  
Icp Ms

&lt;p&gt;Despite being some of the largest bio-constructions on the planet, coral reefs are made by many millions of cm- to mm-sized polyps of Scleractinian corals. Calcification occurs in a micron sized space sandwiched between the coral animal and the existing skeleton, known as the extra cellular medium (ECM). The coral animal has a tight control on the carbonate system in this space through deploying enzymatic pumps (e.g. Ca-ATPase) and secreting acidic-rich proteins. Tracking the state of the carbonate system in the ECM is therefore key to forming a mechanistic understanding of how environmental change, such as ocean acidification, influences skeletal formation and ultimately the growth and resilience of these important ecosystems.&lt;/p&gt;&lt;p&gt;Traditional means to examine ECM composition is through the use of micro-electrodes. While these approaches have revealed many key insights they are, by their nature, invasive.&amp;#160; They also only provide snap shots of information for corals grown in the laboratory. The boron isotopic composition of the coral skeleton and its boron content (expressed as B/Ca ratio) have recently emerged as a viable alternative approach to fully characterise the carbonate system in the ECM.&amp;#160; However, most studies employ bulk sampling techniques which require averaging across both structural elements of the coral skeleton and many months to years of growth. Laser ablation MC-ICP-MS approaches are now available as an alternative sampling protocol (e.g. Standish et al. 2019), and along with B/Ca (and other trace element) measurements this not only allows a reconstruction of the full carbonate system of the ECM from an analysis of the skeleton of any coral (cultured or wild) at unprecedented spatial and temporal resolution, but it also allows an examination of the influence of the carbonate system in the ECM on trace element incorporation.&amp;#160;&lt;/p&gt;&lt;p&gt;Here we present boron isotope and trace element analyses of several tropical, reef-building, corals to examine the nature and magnitude of fine scale variation in ECM composition.&amp;#160; By studying corals from locations where external seawater is well known we also gain insights into trace element incorporation and whether external seawater pH can be accurately reconstructed from the boron-based proxies at weekly (or better) resolution.&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Standish, C.D., Chalk, T.B., Babila, T.L., Milton, J.A., Palmer, M.R., Foster, G.L. (2019) The effect of matrix interferences in situ boron isotope analysis by laser ablation MC-ICP-MS, Rapid Communications in Mass Spectrometry 33: 959&amp;#8211;968 https://doi.org/10.1002/rcm.8432&lt;/p&gt;

scholarly journals Trace Element Micro-Analytical Imaging via Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS)

2011 ◽  
Vol 17 (S2) ◽  
pp. 566-567 ◽  
Author(s):  
A Netting ◽  
J Payne ◽  
B Wade ◽  
T Raimondo
Keyword(s):  
Mass Spectrometry ◽  
Laser Ablation ◽  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Plasma Mass Spectrometry

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

scholarly journals Trace Elements in Magnetite from the Pagoni Rachi Porphyry Prospect, NE Greece: Implications for Ore Genesis and Exploration

Minerals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 725 ◽  
Author(s):  
Constantinos Mavrogonatos ◽  
Panagiotis Voudouris ◽  
Jasper Berndt ◽  
Stephan Klemme ◽  
Federica Zaccarini ◽  
...  
Keyword(s):  
Trace Elements ◽  
Laser Ablation ◽  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Ore Deposits ◽  
Hydrothermal Conditions ◽  
Northern Greece ◽  
Icp Ms ◽  
Accessory Phase ◽  
Granodiorite Porphyry

Magnetite is a common accessory phase in various types of ore deposits. Its trace element content has proven to have critical implications regarding petrogenesis and as guides in the exploration for ore deposits in general. In this study we use LA-ICP-MS (laser ablation-inductively coupled plasma-mass spectrometry) analyses of trace elements to chemically characterize magnetite from the Pagoni Rachi Cu–Mo–Re–Au porphyry-style prospect, Thrace, northern Greece. Igneous magnetite mostly occurs as euhedral grains, which are commonly replaced by hematite in fresh to propylitic-altered granodiorite porphyry, whereas, hydrothermal magnetite forms narrow veinlets or is disseminated in sodic/potassic-calcic altered (albite + K-feldspar + actinolite + biotite + chlorite) granodiorite porphyry. Magnetite is commonly associated with chalcopyrite and pyrite and locally exhibits martitization. Laser ablation ICP-MS analyses of hydrothermal magnetite yielded elevated concentrations in several trace elements (e.g., V, Pb, W, Mo, Ta, Zn, Cu, and Nb) whereas Ti, Cr, Ni, and Sn display higher concentration in its magmatic counterpart. A noteworthy enrichment in Mo, Pb, and Zn is an unusual feature of hydrothermal magnetite from Pagoni Rachi. High Si, Al, and Ca values in a few analyses of hydrothermal magnetite imply the presence of submicroscopic or nano-inclusions (e.g., chlorite, and titanite). The trace element patterns of the hydrothermal magnetite and especially the decrease in its Ti content reflect an evolution from the magmatic towards the hydrothermal conditions under decreasing temperatures, which is consistent with findings from analogous porphyry-style deposits elsewhere.

New Insights Into the Control of Visible Gold Fineness and Deposition: A Case Study of the Sanshandao Gold Deposit, Jiaodong, China

2021 ◽  
Vol 106 (1) ◽  
pp. 135-149
Author(s):  
Hong-Wei Peng ◽  
Hong-Rui Fan ◽  
Xuan Liu ◽  
Bo-Jie Wen ◽  
Yong-Wen Zhang ◽  
...  
Keyword(s):  
Gold Deposit ◽  
Inductively Coupled Plasma ◽  
Gold Mineralization ◽  
Isotope Analysis ◽  
Trace Element Analysis ◽  
Sulfide Minerals ◽  
Element Analysis ◽  
Rock Interaction ◽  
Inductively Coupled ◽  
Icp Ms

Abstract Mineralogical distribution, textures, electron probe microanalysis of visible gold, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) trace element analysis of pyrite, and LA-multicollector (MC-)ICP-MS sulfur isotope analysis of sulfide minerals are examined in an ore zone extending obliquely to –4 km depth in the Sanshandao gold deposit Jiaodong, China. We relate these results to the temporal and spatial ore-forming processes in the deposit to further elucidate the controls on the deposition of visible Au and fineness variation. Two generations of Au mineralization are identified. The early generation is represented by beresitization and quartz-pyrite veins in which visible Au grains are associated with pyrite (Py1 and Py2) and are characterized by high fineness [729–961; fineness = 1000×Au/(Au+Ag)]. Py1 and Py2 are both enriched in Co, Ni, and Bi and depleted in As and Au. Texturally, gold and pyrite are pristine crystals, homogeneous in composition. These features are attributed to the sulfidation of the granitic wallrock (fluid/rock interaction) that effectively destabilizes Au in the ore-forming fluids during pyrite deposition. Fineness decreases continuously from 870 at –2650 m depth to 752 at –420 m depth. The Co and Ni contents of Py1 and Py2 decrease significantly from –4000 m to –420 m depth, whereas the As contents increase. The mean δ34S values of Py1 increase from 10.5 to 11.8‰. The spatial variations are interpreted to be related to gradual cooling, decompression, and an enhanced degree of fluid/rock interaction with decreasing depth, which facilitated the initiation of visible gold mineralization at ca. –2700 m depth. The late generation of Au mineralization is represented by quartz-polysulfide veins in which visible Au grains are associated with multiple sulfide minerals (Py3, galena, chalcopyrite, arsenopyrite, and sphalerite). It is characterized by low fineness (549–719), and heterogeneous textures with Ag-rich parts (218–421). Py3, occurring as the rim of pyrite grain, is interpreted to form by replacement via a dissolution-reprecipitation reaction. Py3 is distinctly enriched in As (median of 10 000 ppm) and Au (2.2 ppm), but depleted in Co, Ni, and Bi. The δ34S values of the polysulfide minerals decrease sharply by 4 to 5‰ at depths from –1909 to –1450 m. These features are interpreted to be generated by significant decompression and phase separation of fluid, where most ore elements (e.g., Au, Ag, As, and base metal elements) are destabilized. Our study suggests that remobilization did not affect the generation of visible Au mineralization at Sanshandao.

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