scholarly journals Geochemical Compositions and Detrital Minerals of Stream Sediments around the Zijinshan Copper-Gold Orefield and Their Implications

Minerals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 32
Author(s):  
Yuntao Li ◽  
Qingye Hou ◽  
Yu Xiao
Keyword(s):  
Iron Oxides ◽  
Stream Sediments ◽  
Detrital Zircons ◽  
Vegetation Coverage ◽  
Element Geochemistry ◽  
Magmatic Rocks ◽  
Icp Ms ◽  
Copper Gold ◽  
The Relationship

Regional geochemical anomalies in stream sediments often have close spatial relationships with metallogenic provinces or ore districts, but the relationships between them have not been examined in depth. In this study, stream sediments were collected around the Zijinshan Copper-Gold Orefield, Fujian Province, China. Element geochemistry, U–Pb geochronology and Hf isotope compositions of detrital zircons, and electron microprobe and LA-ICP-MS analyses of iron oxides were conducted. The aims of this study were to investigate the relationship between the provenance of the stream sediments and ore-bearing magmatic rocks in the Zijinshan Copper-Gold Orefield, and to explore the enrichment mechanism of the ore-forming elements in stream sediments. The results show that the ore-forming elements and their associated elements are most significantly enriched in stream sediments near the orefield. U–Pb ages and Hf isotopic compositions of detrital zircons in the sediments closest to the orefield carry information on the ore- bearing magmatic rocks in the orefield. However, as the stream sediments are relatively far from the orefield, the degree of enrichment of ore-forming elements and the detrital zircon U–Pb age signals of the ore-bearing magmatic rocks in the orefield rapidly weaken. This weakening of the geochemical signals may have been affected by many factors, such as lithological resistance to weathering, vegetation coverage, micro-topographic conditions, etc. In-situ elements analysis of iron oxides and elemental correlation analysis of stream sediments indicate iron oxides and clay minerals are the main carrier minerals for the migration of ore-forming elements.

scholarly journals Supplemental Material: Himalayan Miocene adakitic rocks, a case study of the Mayum pluton: Insights into geodynamic processes within the subducted Indian continental lithosphere and Himalayan mid-Miocene tectonic regime transition

2020 ◽  
Author(s):  
Chao Lin ◽  
Jinjiang Zhang ◽  
et al.
Keyword(s):  
Isotopic Composition ◽  
Continental Lithosphere ◽  
Isotopic Data ◽  
Element Geochemistry ◽  
Adakitic Rocks ◽  
Icp Ms ◽  
Geodynamic Processes ◽  
Data Statistics

Table S1: Bulk element geochemistry and isotopic composition of the Mayum pluton; Table S2: Zircon LA-ICP-MS U-Pb data for the Mayum pluton; Table S3: Zircon in situ Lu-Hf isotopic data for the Mayum pluton; Table S4: Data statistics for Himalayan Eocene and Miocene adakitic rocks.

A mid-Cretaceous alkaline volcano in the Davis Strait

2020 ◽  
Vol 57 (1) ◽  
pp. 69-86
Author(s):  
C. Knudsen ◽  
U. Gregersen ◽  
T.F. Kokfelt ◽  
M. Olivarius ◽  
T.B. Thomsen
Keyword(s):  
Gamma Ray ◽  
Volcanic Rocks ◽  
Detrital Zircons ◽  
Magmatic Differentiation ◽  
Volcanic Origin ◽  
Icp Ms ◽  
Davis Strait ◽  
Magma Compositions ◽  
Gamma Ray Log

The AT2-1 well in the Davis Strait between Canada and Greenland penetrated an approximately 1.2 km thick sequence of alkaline volcanic rocks with some intercalated sediments at depths between 3690 to 4850 m. These volcanic rocks can be mapped on 2D seismic data and constitute a cone-shaped 5 km × 10 km wide and >1.2 km high structural high named the Atammik Volcano. This sequence comprises two distinct parts, an upper part of phono-tephrite to basaltic trachy-andesite and a lower part of tephriphonolite and phonolite. Rock textures and structures testify to a volcanic origin, with the uppermost units showing textural evidence of being subaerially extruded. Zircon crystals found in a sample of phonolite from 4453 m were dated by in situ laser ablation ICP–MS technique to yield ages between 98 and 93 Ma, indicating a maximum age of the formation of the phonolitic volcano of 93 Ma (Turonian). Further, detrital zircons from the clastic material have been dated yielding Archean ages. The gamma ray log indicates three internal cycles within the phonolites, each cycle displaying a stratigraphically upwards decrease in potassium content, suggesting the existence of a longer-lived system undergoing repeated magmatic differentiation and eruption events. The upper volcanic sequence is less evolved and less alkaline than the lower, suggesting a change in primary magma compositions towards progressively higher degrees of melting of the underlying mantle. This fits into a scheme of progressively higher degrees of melting with time, which in a regional context probably corresponds to a rifting event.

scholarly journals A Multi-scale Analysis of Urban Warming in Residential Areas of a Latin American City: The Case of Mérida, Mexico

2020 ◽  
pp. 0739456X2092300
Author(s):  
James J. Biles ◽  
David S. Lemberg
Keyword(s):  
Latin American ◽  
Vegetation Coverage ◽  
American City ◽  
Residential Areas ◽  
Ambient Temperatures ◽  
Multi Scale ◽  
Urban Warming ◽  
City Structure ◽  
The Relationship

This study represents a novel attempt to analyze the relationship between Latin American city structure and residential-scale ambient temperatures. Using statistical analysis, we assess the relationship between type of residential zone, vegetation coverage, and housing and lot characteristics and ambient temperatures in residential areas of a large, subtropical city. We find lower temperatures in two residential areas, as well as an association between vegetation coverage and in situ characteristics. We conclude that the factors contributing to urban warming are a legacy of the study area’s unique historical geography; consequently, policy recommendations must be place-specific, integrating meso, micro, and in situ factors.

scholarly journals Trace-Element Geochemistry of Sulfides in Upper Mantle Lherzolite Xenoliths from East Antarctica

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 773
Author(s):  
Alexandre V. Andronikov ◽  
Irina E. Andronikova ◽  
Tamara Sidorinova
Keyword(s):  
Trace Element ◽  
Upper Mantle ◽  
East Antarctica ◽  
Trace Element Geochemistry ◽  
Sulfide Liquid ◽  
Element Geochemistry ◽  
Element Partitioning ◽  
Icp Ms ◽  
Modal Abundance

Sulfides in upper mantle lherzolite xenoliths from Cretaceous alkaline-ultramafic rocks in the Jetty Peninsula (East Antarctica) were studied for their major and trace-element compositions using SEM and LA-ICP-MS applied in situ. Modal abundance of sulfides is the lowest in Cpx-poor lherzolites ≤ Spl-Grt lherzolites << Cpx-rich lherzolites. Most sulfides are either interstitial (i-type) or inclusions in rock-forming minerals (e-type) with minor sulfide phases mostly present in metasomatic veinlets and carbonate-silicate interstitial patches (m-type). The main sulfide assemblage is pentlandite + chalcopyrite ± pyrrhotite; minor sulfides are polydymite, millerite, violarite, siegenite, and monosulfide solution (mss). Sulfide assemblages in the xenolith matrix are a product of the subsolidus re-equilibration of primary mss at temperatures below ≤300 °C. Platinum group elements (PGE) abundances suggest that most e-type sulfides are the residues of melting processes and that the i-type sulfides are crystallization products of sulfide-bearing fluids/liquids. The m-type sulfides might have resulted from low-temperature metasomatism by percolating sulfide-carbonate-silicate fluids/melts. The PGE in sulfide record processes are related to partial melting in mantle and intramantle melt migration. Most other trace elements initially partitioned into interstitial sulfide liquid and later metasomatically re-enriched residual sulfides overprinting their primary signatures. The extent of element partitioning into sulfide liquids depends on P, T, fO2, and host peridotite composition.

scholarly journals Supplemental Material: Himalayan Miocene adakitic rocks, a case study of the Mayum pluton: Insights into geodynamic processes within the subducted Indian continental lithosphere and Himalayan mid-Miocene tectonic regime transition

2020 ◽  
Author(s):  
Chao Lin ◽  
Jinjiang Zhang ◽  
et al.
Keyword(s):  
Isotopic Composition ◽  
Continental Lithosphere ◽  
Isotopic Data ◽  
Element Geochemistry ◽  
Adakitic Rocks ◽  
Icp Ms ◽  
Geodynamic Processes ◽  
Data Statistics

Table S1: Bulk element geochemistry and isotopic composition of the Mayum pluton; Table S2: Zircon LA-ICP-MS U-Pb data for the Mayum pluton; Table S3: Zircon in situ Lu-Hf isotopic data for the Mayum pluton; Table S4: Data statistics for Himalayan Eocene and Miocene adakitic rocks.

ZIRCON TRACE ELEMENT GEOCHEMISTRY AS AN INDICATOR OF MAGMA FERTILITY IN IRON OXIDE COPPER-GOLD PROVINCES

2021 ◽  
Author(s):  
C. E. Wade ◽  
J. L. Payne ◽  
K. Barovich ◽  
S. Gilbert ◽  
B. P. Wade ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Trace Element ◽  
Large Igneous Province ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
Magma Evolution ◽  
Magmatic Rocks ◽  
Copper Gold ◽  
Ree Patterns

Abstract Extrusive and intrusive felsic magmas occur throughout the evolution of silicic-dominated large igneous province magmatism that is temporally related to numerous economically significant iron oxide copper-gold (IOCG) deposits in southern Australia. We investigate zircon trace element signatures of the felsic magmas to assess whether zircon composition can be related to fertility of the volcanic and intrusive suites within IOCG-hosted mineral provinces. Consistent with zircon forming in oxidizing magmatic conditions, the rare earth element (REE) patterns of zircon sourced from both extrusive and intrusive magmatic rocks are characterized by light REE depletions and a range of positive Ce and negative Eu anomalies. The timing of the major phase of IOCG mineralization overlaps with the early part of the first phase of Lower Gawler Range Volcanics magmatism (1593.6–1590.4 Ma) and older intrusive magmatism of the Hiltaba Suite (1593.06–1590.50 Ma). Zircon in these mineralization-related intrusives and extrusives is distinguished from zircon in younger, mineralization-absent rocks by higher Eu/Eu*, Ce/Ce*, and Ti values and separate magma evolution paths with respect to Hf. These zircon characteristics correspond to lower degrees of fractionation and/or crustal assimilation, more oxidizing magmatic conditions, and higher magmatic temperatures, respectively, in magmas coeval with mineralization. In this respect, we consider higher oxidation state, lower degrees of fractionation, and higher magmatic temperatures to be features of fertile magmas in southern Australian IOCG terrains. Similar zircon REE characteristics are shared between magmas associated with southern Australian IOCG and iron oxide-apatite (IOA) rhyolites from the St. Francois Mountains, Missouri, namely high Ce/Ce* and high Dy/Yb, indicative of oxidized and dry magmas, respectively. The dry and more fractionated nature of the IOCG- and IOA-associated magmas contrasts with the hydrous and unfractionated nature of fertile porphyry Cu deposit magmas. As indicated by high Ce/Ce* ratios, the oxidized nature is considered a key element in magma fertility in IOCG-IOA terrains. In both IOCG and IOA terrains, the trace element compositions of zircon are able to broadly differentiate fertile from nonfertile magmatic rocks.

scholarly journals In situ Sr isotope analyses by LA-MC-ICP-MS of igneous apatite and plagioclase from magmatic rocks at the CPGeo-USP

2016 ◽  
Vol 46 (suppl 1) ◽  
pp. 227-243
Author(s):  
Patricio Montecinos Munoz ◽  
Adriana Alves ◽  
Rogério Guitarrari Azzone ◽  
Pablo Cordenons ◽  
Sandra Morano ◽  
...  
Keyword(s):  
Magma Mixing ◽  
Successful Implementation ◽  
Geochemical Processes ◽  
Sr Isotope ◽  
Magmatic Rocks ◽  
Icp Ms ◽  
Isotope Analyses ◽  
Better Than

ABSTRACT: This contribution describes the successful implementation of in situ Sr isotope analyses by LA-MC-ICP-MS at the CPGeo-USP. The choice for an analytical configuration using measurements of half-masses allows the accurate assessment of lanthanide interferences, permitting the determination of Sr isotopes in important REE-rich accessory phases, such as apatite. Likewise, the on-peak-zero method effectively corrects the background contribution (both from Kr and residual Sr contributions from previous ablations) to the signals of the unknown samples. The analytical campaigns resulted in an accuracy, in respect to reference TIMS values, better than 57 ppm (~ ±0.000057 2σ SD) for a modern coral and the Batjberg clinopyroxene which impart significant quality to our data. Similarly, the majority of the stable Sr isotope ratios are close to the accepted values, which also confirms the effectiveness of the method. The achieved accuracy allows the identification and investigation of spatially-controlled isotopic heterogeneities on the micrometric scale in several Sr-rich minerals (apatite, carbonates, plagioclase, and clinopyroxene) with important implications to the understanding of relevant geochemical processes, particularly AFC, source geochemical heterogeneities and magma-mixing.

Profile Imaging of Silicon Surface Reconstructions

1985 ◽  
Vol 43 ◽  
pp. 262-263
Author(s):  
O.L. Krivanek ◽  
G.J. Wood
Keyword(s):  
Electron Microscopy ◽  
Surface Structure ◽  
Structure Determination ◽  
Silicon Surface ◽  
Good Resolution ◽  
Surface Reconstructions ◽  
Bulk Structure ◽  
Point To Point ◽  
The Relationship

Electron microscopy at 0.2nm point-to-point resolution, 10-10 torr specimei region vacuum and facilities for in-situ specimen cleaning presents intere; ing possibilities for surface structure determination. Three methods for examining the surfaces are available: reflection (REM), transmission (TEM) and profile imaging. Profile imaging is particularly useful because it giv good resolution perpendicular as well as parallel to the surface, and can therefore be used to determine the relationship between the surface and the bulk structure.

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