scholarly journals Chemical Constraints on the Origin of the Frailes Volcanic Complex in the Central Andean Altiplano Plateau, Bolivia

2018 ◽  
Author(s):  
C. Brenhin Keller
Keyword(s):  
Trace Element Analysis ◽  
Small Region ◽  
Volcanic Complex ◽  
Main Body ◽  
Element Analysis ◽  
Andean Altiplano ◽  
Arc Setting ◽  
Geochemical Analyses ◽  
Back Arc ◽  
Lower Crustal

The Frailes volcanic complex of the Bolivian Altiplano plateau is the largest and most prominent ignimbrite of the Andean Central Volcanic Zone. With 2000 km3 of exposed volcanic deposits dating from 25 Ma to the present, the complex provides insight into the processes of large-volume silicic melt formation in a back-arc setting. However, the voluminous 0-10 Ma main body of the Frailes complex remains poorly studied, as the majority of the literature focuses on a small region of 12-14 Ma Sn-Ag mineralization at Cerro Rico – the world's largest silver deposit. Here, we present geochemical analyses of 25 representative samples from our fieldwork on the Frailes ignimbrite. Whole-rock major element analysis by X-ray fluorescence spectroscopy showed the ~ 7 Ma samples to be highly peraluminous, potassic (>5% K2O) andesitic to rhyodacitic welded volcanic tuffs with an Al-rich, chemically reduced mineral assemblage including biotite, calcic feldspar, magmatic cordierite, and ilmenite. Trace element analysis by instrumental neutron activation revealed steep rare earth patterns with Sm/Yb > 5.0, requiring the presence of garnet in a deep-crustal, high-pressure restitic assemblage. In contrast, the presence of cordierite indicates crystallization at low pressure (< 450 MPa), at depths of less than 14 km. In addition, geochemical analyses combined with the geocronological work of Barke et al. (2007) support a recent (~2 Ma) age for the ignimbrites of the main Frailes Meseta. These ignimbrites are consequently best explained by mixing of a mantle- derived melt with a reduced, lower crustal component at great depths to produce hybrid magmas that ascended and evolved to form shallow crustal (<14 km) magma bodies before erupting in catastrophic, caldera-forming events at ~2 Ma.

scholarly journals The Petrology and Geochemistry of a Suite of Intrusive Igneous Rocks from the Southern Kermadec Arc-Havre Trough, SW Pacific

2021 ◽  
Author(s):  
Brenton Tozer
Keyword(s):  
Magma Chamber ◽  
Igneous Rocks ◽  
Magmatic System ◽  
Sw Pacific ◽  
Petrology And Geochemistry ◽  
Geochemical Analyses ◽  
Lower Temperature ◽  
Back Arc ◽  
Lower Crustal

<p>The study of intrusive igneous rocks can provide insights into deep crustal processes. In active intraoceanic arc environments, the opportunity to study of these intrusive igneous rocks usually comes from xenoliths entrained within eruptive products, as accessibility to in situ intrusive rocks is limited. This thesis documents a suite of the first intrusive samples dredged from the Havre Trough, which provide insights into deep magmatic processes in this intraoceanic back-arc system. The suite of ten intrusive igneous rocks were dredged from Basin E, a back-arc basin (BAB) in the Kermadec Arc-Havre Trough (KAHT) and consist of in situ gabbroic meso- to orthocumulates. Four representative samples were selected from the suite of ten on the basis of grainsize, and from them a petrogenetic model was built to determine the associations of the samples within the magmatic system of the region. The four samples all exhibit comparable mineral assemblages of plagioclase, clinopyroxene, and magnetite, with olivine and orthopyroxene absent. Texturally the samples appear to have formed in (a) magma chamber(s) where the minerals cooled slowly and formed relatively large, euhedral crystals that trapped interstitial melt between them. The interstitial melts crystallised forming more evolved intercumulus material (plagioclase + quartz ± amphibole ± apatite). Three of the four samples have coarser grainsizes (1-2 mm), and exhibit similar magnetite temperature estimates, indicating that they formed from similar melts. The other sample has a finer grainsize (<1 mm), and exhibits lower temperature estimates, indicating that this sample formed from a lower temperature, faster cooling melt. Plagioclase compositions follow a similar trend to plagioclase phenocrysts from modern back-arc volcanoes which indicates that these samples have an association with the modern magmatic system rather than the now extinct Miocene (Colville) Arc. Clinopyroxene trace element data are also consistent with these samples being associated with the modern subduction system. The magma chamber(s) that the samples formed in, comes from a mid-lower crustal depth, 3-6 km based on pressure estimates from amphibole crystal chemistry. The exposure of rocks from this depth would have been facilitated by normal faulting associated with rifting and opening of the Havre Trough. Petrologic and geochemical analyses of these cumulates suggest that the deep, back-arc basins consist of entirely new magmatic material formed from BAB volcanism, with no evidence for pre-existing crust.</p>

scholarly journals The Petrology and Geochemistry of a Suite of Intrusive Igneous Rocks from the Southern Kermadec Arc-Havre Trough, SW Pacific

2021 ◽  
Author(s):  
Brenton Tozer
Keyword(s):  
Magma Chamber ◽  
Igneous Rocks ◽  
Magmatic System ◽  
Sw Pacific ◽  
Petrology And Geochemistry ◽  
Geochemical Analyses ◽  
Lower Temperature ◽  
Back Arc ◽  
Lower Crustal

<p>The study of intrusive igneous rocks can provide insights into deep crustal processes. In active intraoceanic arc environments, the opportunity to study of these intrusive igneous rocks usually comes from xenoliths entrained within eruptive products, as accessibility to in situ intrusive rocks is limited. This thesis documents a suite of the first intrusive samples dredged from the Havre Trough, which provide insights into deep magmatic processes in this intraoceanic back-arc system. The suite of ten intrusive igneous rocks were dredged from Basin E, a back-arc basin (BAB) in the Kermadec Arc-Havre Trough (KAHT) and consist of in situ gabbroic meso- to orthocumulates. Four representative samples were selected from the suite of ten on the basis of grainsize, and from them a petrogenetic model was built to determine the associations of the samples within the magmatic system of the region. The four samples all exhibit comparable mineral assemblages of plagioclase, clinopyroxene, and magnetite, with olivine and orthopyroxene absent. Texturally the samples appear to have formed in (a) magma chamber(s) where the minerals cooled slowly and formed relatively large, euhedral crystals that trapped interstitial melt between them. The interstitial melts crystallised forming more evolved intercumulus material (plagioclase + quartz ± amphibole ± apatite). Three of the four samples have coarser grainsizes (1-2 mm), and exhibit similar magnetite temperature estimates, indicating that they formed from similar melts. The other sample has a finer grainsize (<1 mm), and exhibits lower temperature estimates, indicating that this sample formed from a lower temperature, faster cooling melt. Plagioclase compositions follow a similar trend to plagioclase phenocrysts from modern back-arc volcanoes which indicates that these samples have an association with the modern magmatic system rather than the now extinct Miocene (Colville) Arc. Clinopyroxene trace element data are also consistent with these samples being associated with the modern subduction system. The magma chamber(s) that the samples formed in, comes from a mid-lower crustal depth, 3-6 km based on pressure estimates from amphibole crystal chemistry. The exposure of rocks from this depth would have been facilitated by normal faulting associated with rifting and opening of the Havre Trough. Petrologic and geochemical analyses of these cumulates suggest that the deep, back-arc basins consist of entirely new magmatic material formed from BAB volcanism, with no evidence for pre-existing crust.</p>

An improved interference correction for trace element analysis

1992 ◽  
Vol 50 (2) ◽  
pp. 1646-1647
Author(s):  
John J. Donovan ◽  
Donald A. Snyder ◽  
Mark L. Rivers
Keyword(s):  
Trace Element Analysis ◽  
Accurate Estimate ◽  
Simple Expression ◽  
Standard Reference Materials ◽  
Characteristic Line ◽  
Analytical Line ◽  
Element Analysis ◽  
Electron Probe Analysis ◽  
Calculated Concentration ◽  
X Ray

We present a simple expression for the quantitative treatment of interference corrections in x-ray analysis. WDS electron probe analysis of standard reference materials illustrate the success of the technique.For the analytical line of wavelength λ of any element A which lies near or on any characteristic line of another element B, the observed x-ray counts at We use to denote x-ray counts excited by element i in matrix j (u=unknown; s=analytical standard; ŝ=interference standard) at the wavelength of the analytical line of A, λA (Fig. 1). Quantitative analysis of A requires an accurate estimate of These counts can be estimated from the ZAF calculated concentration of B in the unknown C,Bu measured counts at λA in an interference standard of known concentration of B (and containing no A), and ZAF correction parameters for the matrices of both the unknown and the interference standard at It can be shown that:

Reconstructing sea turtle ontogenetic habitat shifts through trace element analysis of bone tissue

2019 ◽  
Vol 608 ◽  
pp. 247-262 ◽  
Author(s):  
MD Ramirez ◽  
JA Miller ◽  
E Parks ◽  
L Avens ◽  
LR Goshe ◽  
...  
Keyword(s):  
Trace Element ◽  
Bone Tissue ◽  
Trace Element Analysis ◽  
Sea Turtle ◽  
Element Analysis ◽  
Ontogenetic Habitat Shifts

Method of Detecting Trace Metal Contamination in Thick-Film SOI Device

2005 ◽  
Author(s):  
Yasunori Goto ◽  
Hiroomi Eguchi ◽  
Masaru Iida
Keyword(s):  
Trace Metal ◽  
Thick Film ◽  
Metal Contamination ◽  
Semiconductor Device ◽  
Trace Element Analysis ◽  
Silicon On Insulator ◽  
Element Analysis ◽  
Trace Metal Contamination ◽  
Trace Metal Elements ◽  
Output Characteristics

Abstract In the automotive IC using thick-film silicon on insulator (SOI) semiconductor device, if the gettering capability of a SOI wafer is inadequate, electrical characteristics degradation by metal contamination arises and the yield falls. At this time, an automotive IC was made experimentally for evaluation of the gettering capability as one of the purposes. In this IC, one of the output characteristics varied from the standard, therefore failure analysis was performed, which found trace metal elements as one of the causes. By making full use of 3D perspective, it is possible to fabricate a site-specific sample into 0.1 micrometre in thickness without missing a failure point that has very minute quantities of contaminant in a semiconductor device. Using energy dispersive X-ray, it is possible to detect trace metal contamination at levels 1E12 atoms per sq cm. that are conventionally detected only by trace element analysis.

Stratigraphy, structure and geochemistry of Archaean supracrustal rocks from Oqaatsut and Naajaat Qaqqaat, north-east Disko Bugt, West Greenland

1999 ◽  
pp. 65-78
Author(s):  
Henrik Rasmussen ◽  
Lars Frimodt Pedersen
Keyword(s):  
Tectonic Setting ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
West Greenland ◽  
North West ◽  
North East ◽  
Metavolcanic Rocks ◽  
Arc Setting ◽  
Area North ◽  
Back Arc

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Rasmussen, H., & Frimodt Pedersen, L. (1999). Stratigraphy, structure and geochemistry of Archaean supracrustal rocks from Oqaatsut and Naajaat Qaqqaat, north-east Disko Bugt, West Greenland. Geology of Greenland Survey Bulletin, 181, 65-78. https://doi.org/10.34194/ggub.v181.5114 _______________ Two Archaean supracrustal sequences in the area north-east of Disko Bugt, c. 1950 and c. 800 m in thickness, are dominated by pelitic and semipelitic mica schists, interlayered with basic metavolcanic rocks. A polymict conglomerate occurs locally at the base of one of the sequences. One of the supracrustal sequences has undergone four phases of deformation; the other three phases. In both sequences an early phase, now represented by isoclinal folds, was followed by north-west-directed thrusting. A penetrative deformation represented by upright to steeply inclined folds is only recognised in one of the sequences. Steep, brittle N–S and NW–SE striking faults transect all rock units including late stage dolerites and lamprophyres. Investigation of major- and trace-element geochemistry based on discrimination diagrams for tectonic setting suggests that both metasediments and metavolcanic rocks were deposited in an environment similar to a modern back-arc setting.

Trace Element Analysis of Fusel Oil by Microwave-Induced Plasma Optical Emission Spectrometry

2017 ◽  
Vol 13 (6) ◽  
Author(s):  
Daniel Araujo Goncalves ◽  
Tina McSweeney ◽  
Mirian Cristina dos Santos ◽  
Marco A. Utrera Martines ◽  
Luiz Francisco Malmonge ◽  
...  
Keyword(s):  
Trace Element ◽  
Trace Element Analysis ◽  
Optical Emission ◽  
Optical Emission Spectrometry ◽  
Emission Spectrometry ◽  
Element Analysis ◽  
Fusel Oil ◽  
Microwave Induced Plasma ◽  
Plasma Optical Emission Spectrometry
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