Geology and geochemistry of the molybdenite showings of the Ackley City batholith, southeast Newfoundland

1980 ◽  
Vol 17 (9) ◽  
pp. 1246-1258 ◽  
Author(s):  
J. B. Whalen
Keyword(s):  
Trace Elements ◽  
Vapour Phase ◽  
Major And Trace Elements ◽  
Composite Body ◽  
Precambrian Rocks ◽  
Geological Features ◽  
Tectonic Zones ◽  
Host Rocks ◽  
Residual Melt

The Ackley City batholith of southeast Newfoundland is an oval-shaped granitoid of approximately 5400 km2 which intruded Ordovician and Precambrian rocks of the Gander and Avalon tectonic zones, respectively, about 345 Ma ago. It is a composite body, consisting mainly of K-feldspar megacrystic granite and alaskite. Spatially related to the southeast contact of the alaskite are younger aplites and pegmatites within which are six separate molybdenite showings. The showings vary in their type of host rocks and in features of mineralization and alteration, but can all be classed as being of aplite–pegmatite type.This notably felsic (SiO2 > 71.8%) pluton has alkaline affinities and features indicative of derivation from an igneous source (I-type). Some major and trace elements exhibit considerable variations. These variations and other geological features indicate that aplites and pegmatites formed by in situ fractional crystallization of the alaskite at shallow depths (1.8 to 3.7 km) to produce a roof-zone complex. Mo is localized in these rocks, which formed from the final residual melt and coexisting vapour phase, and is considered to be closely genetically related to them.

scholarly journals In Situ Chalcophile and Siderophile Element Behavior in Sulfides from Moroccan Middle Atlas Spinel Peridotite Xenoliths during Metasomatism and Weathering

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 276 ◽  
Author(s):  
Katrin J. Westner ◽  
Christoph Beier ◽  
Reiner Klemd ◽  
Inga Osbahr ◽  
Nadine Brooks
Keyword(s):  
Trace Elements ◽  
Solid Solutions ◽  
Inductively Coupled Plasma ◽  
Major And Trace Elements ◽  
Spinel Peridotite ◽  
Inductively Coupled ◽  
Plasma Mass Spectrometry ◽  
Middle Atlas ◽  
Mantle Processes

In situ chalcophile and siderophile major and trace elements were analyzed in sulfides from eight Moroccan Middle Atlas lherzolite xenoliths using electron microprobe and laser ablation inductively coupled plasma mass spectrometry. The sulfides occur enclosed in primary silicates, interstitial in the peridotite matrix, and associated with glass-bearing melt pockets. Monosulfide solid solutions are enriched in these xenoliths relative to pentlandite and intermediate solid solutions. Regardless of the textural occurrence, sulfide platinum-group element (PGE) patterns are distinguished into residual ([Pd/Ir]N < 1 and [Pt/Pd]N > 1 or [Pt/Pd]N < 1), melt-like ([Pd/Ir]N > 1), and unfractionated patterns. The coexistence of both residual and melt-like PGE signatures on a cm scale in a single sample implies that sulfides may record initial depletion and subsequent re-enrichment more effectively than constituent silicates do. Chalcophile and siderophile trace elements other than the PGEs are fractionated between the precipitated sulfide phases, but do not vary systematically with the PGE signatures, suggesting that the PGEs are comparatively sensitive to melting and depletion. In addition, Fe-rich hydroxides generated by sulfide breakdown due to atmospheric weathering display PGE systematics almost identical to their precursor sulfides, implying that they may be reliable tracers of mantle processes even after extensive weathering.

The petrology of the Lugar Sill, SW Scotland

1987 ◽  
Vol 77 (4) ◽  
pp. 325-347 ◽  
Author(s):  
C. M. B. Henderson ◽  
F. G. F. Gibb
Keyword(s):  
Trace Elements ◽  
Magma Chamber ◽  
Major And Trace Elements ◽  
Central Unit ◽  
Residual Liquid ◽  
Multiple Injections ◽  
Incompatible Elements ◽  
Complete Section ◽  
Drill Cores

ABSTRACTA 49 m complete section through the 288 Ma Lugar Sill obtained from drill cores can be subdivided into nine units. The uppermost four units are teschenitic and are mirror images of the bottom four. A 35 m thick central unit consists of theralite passing down into kaersutite theralite and then picrite. Marginal chilling 'of the units indicates multiple intrusion from the outside inwards. Olivine in the central unit (Fo88–90) encloses Cr-rich spinels and increases in amount inwards to over 50%. Clinopyroxene, kaersutite and biotite show symmetrically increasing Fe/Mg from the centre of the sill outwards. Most major and trace elements vary symmetrically throughout the sill with those in the central unit reflecting mainly olivine distribution but incompatible elements exhibit upward enrichment. Remarkably, the most-evolved rocks in the sill are at its margins. The sill was formed by multiple injections of successively less-evolved teschenitic magmas followed by a larger pulse of theralitic liquid carrying abundant olivine phenocrysts. The amount of olivine in this final pulse increased during emplacement. Subsequent in-situ differentiation in the central unit, with upward enrichment in residual liquid and volatiles, gave rise to lugarites. The various magmas were produced in a lower-level magma chamber by differentiation of a mantle-derived, alkali-rich picritic magma.

In situ analysis of major and trace elements of anhydrous minerals by LA-ICP-MS without applying an internal standard

2008 ◽  
Vol 257 (1-2) ◽  
pp. 34-43 ◽  
Author(s):  
Yongsheng Liu ◽  
Zhaochu Hu ◽  
Shan Gao ◽  
Detlef Günther ◽  
Juan Xu ◽  
...  
Keyword(s):  
Trace Elements ◽  
Internal Standard ◽  
Major And Trace Elements ◽  
In Situ Analysis ◽  
Icp Ms

scholarly journals MK-1 Orthopyroxene—A New Potential Reference Material for In-Situ Microanalysis

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1321
Author(s):  
Lihui Jia ◽  
Qian Mao ◽  
Bin Su ◽  
Shitou Wu ◽  
Liangliang Huang ◽  
...  
Keyword(s):  
Trace Elements ◽  
Reference Material ◽  
Analytical Techniques ◽  
Major And Trace Elements ◽  
Major Elements ◽  
Metamorphic Belt ◽  
Ultramafic Intrusion ◽  
Binocular Microscope ◽  
Good Agreement

Orthopyroxene, an important phase in mantle-derived rocks, has become a powerful tool to unravel mantle nature and magma processes. However, the applications have been hindered by the lag in the development of analytical techniques, such as shortage of reference materials. Orthopyroxene grains derived from an ultramafic intrusion at the Mogok metamorphic belt (Myanmar) were evaluated for the potential use of orthopyroxene as a reference material for in-situ microanalysis. Approximately 20 g of 0.5–3 mm pure orthopyroxene grains were separated under binocular microscope and analyzed using EPMA, LA-ICPMS, and bulk analytical methods (XRD, XRF, and solution-ICPMS) for major and trace elements at four institutions. Eleven core-to-rim profiles carried out using EPMA and twelve core-to-rim profiles determined using LA-ICPMS suggest that MK-1 orthopyroxene grains are sufficiently homogeneous, with RSD < ±2% (1σ) for major elements (Mg, Si, and Fe) and RSD < ±10% (1σ) for trace elements (Na, Al, Ca, Ti, Cr, Co, Zn, Ni, Mn, Sc, and V). In addition, the composition of MK-1 orthopyroxene was also measured by XRF and solution-ICPMS measurements in two different laboratories, to compare with the results measured using EPMA and LA-ICPMS. The results indicated a good agreement with RSE < ±2% (1σ) for major elements and RSE < ±5% (1σ) for most trace elements, except for Na (±9.73%) and Ti (±6.80%). In an overall assessment of these data, MK-1 orthopyroxene can be considered as a reference material for in-situ microanalysis, which would provide solid trace elements data for a better understanding of mantle source and magmatic evolution.

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