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Incompatible element

About: Incompatible element is a research topic. Over the lifetime, 2420 publications have been published within this topic receiving 154052 citations.


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TL;DR: In this article, the authors distinguish two rhyolite types that occur in these fields and summarize their geology, petrography, and geochemistry, and make a distinction of HSR and LSR lavas based on phenocryst assemblages.
Abstract: Bimodal basalt-rhyolite fields that erupted since 15 Ma form a NE trending line that crosses the boundary between the Basin and Range and the Colorado Plateau in western Arizona. The bimodal volcanism traverses physiographic province boundaries marked by changes in crustal thickness. Silicic volcanism in these fields postdates detachment faulting in the Basin and Range and generally decreases in age from south to north. We distinguish two rhyolite types that occur in these fields and summarize their geology, petrography, and geochemistry. Both high-silica (HSR) and low-silica rhyolites (LSR) occur in these fields. HSR lavas contain >75 wt % SiO2 (normalized to 100% volatile free), have high concentrations of incompatible elements (Rb, U, Th, Cs, Ta), low concentrations of compatible elements (Ba, Sr, Eu, Mg, Cr), and relatively flat rare earth element (REE) patterns (La/LuN 8). Further distinction of HSR and LSR lavas is made based on phenocryst assemblages. Trace element and isotopic studies suggest that both the HSR and LSR lavas contain a major crustal component and that the HSR lavas may have formed by extensive crystal fractionation of LSR parent magmas. HSR and LSR lavas display systematic compositional variations along the transect; however, their compositions diverge from south to north. HSR lavas erupted on the Colorado Plateau are more differentiated than those erupted in the Basin and Range, perhaps reflecting more extensive crystal fractionation while ascending the thicker crust of the Colorado Plateau province. In contrast, LSR lavas on the Colorado Plateau are more primitive than those in the Basin and Range. This seeming paradox may be related to lateral changes in source composition, possibly caused by a northerly increase in either metamorphic grade or bulk composition. Alternative models for the LSR compositional variations, such as magma mixing and mantle input into lower crustal sources, cannot be tested with our present data.

15 citations

01 Jan 1993
TL;DR: The bulk compositions of two Antarctic Lodranites, MAC 88177 and FRO 90011, and two Acapulcoites, ALH 81261 and Monument Draw, were determined with instrumental neutron activation analysis as mentioned in this paper.
Abstract: The bulk compositions of two Antarctic Lodranites, MAC 88177 and FRO 90011, and two Acapulcoites, ALH 81261 and Monument Draw, were determined with instrumental neutron activation analysis. Acapulcoites have essentially chondritic major and trace element abundances but achondritic texture. They consist of entirely recrystallized, fine grained mineral assemblages. Chondrules are extremely rare; one relict radiating pyroxene chondrule was described in Monument Draw (MD). The coarse grained Lodranites also have achondritic textures, but they are different compositionally with depletions in Al, Na, and incompatible elements probably a result of separation of partial, feldspar-rich melt. MAC 88177 is significantly more depleted in incompatible elements than FRO 90011 suggesting a higher degree of partial melting for the MAC-Lodranite. The chemical data support a genetic relationship between Lodranites and Acapulcoites inferred earlier from oxygen isotopes, petrology, and mineral composition.

15 citations

Journal Article
TL;DR: Shesuo deposit is located in the north of Shenzha county, Tibet as discussed by the authors, it is near the Bangong Lake-Nujiang metallogenic belt, and a small skarn type copper-richen polymetallic deposit.
Abstract: Shesuo deposit is located in the north of Shenzha county, Tibet. It is near the Bangong Lake-Nujiang metallogenic belt, and a small skarn type copper-richen polymetallic deposit. This paper is based on the systemic field geological survey, indoor rock and ore appraisal, zircon LA-ICP-MS U-Pb dating, test of major and trace element, H-O, C, S and Pb isotopes, Raman spectra, temperature and salinity of fluid inclusions, and find out its chronology and geochemical characteristics. The age of granodiorites which is metallogenic rock is 116Ma, A/CNK value is near 1.0, A/NK value 1.62~1.88. The roceks belong to transition types between metaluminous and ultraluminum. In the spider diagram of trace elements, big ion incompatible elements Rb, Th, Pb and Ti are rich, and Nb is poor. The distribution pattern of rare earth elements is right-trending type, and the curve of heavy rare-earth elements is gentle, ∑REE is range from 89.89×10-6 to 97.92×10-6, ∑LREE/∑HREE=7.47~9.31, δEu=0.75~0.89, and namely it has no obvious negative Eu abnormalities. Bangong Lake-Nujiang oceanic crust subducts southward (Gangdes plot). The deposit formed in island-arc environment. Pb isotopes of granodiorites which are metallogenic rocks reflects that it belongs to crust source. The date of H and O isotopes of inclusions in sulfide-quartz veins shows that it mainly belongs to the magma water. The δ13CV-PDB of calcite ranges from -3.6‰ to -2.0‰; The δ34SV-CDT=10.3‰~2.7‰, and they are negative values, and mainly appear -8.5‰ and -3.5‰ two peaks, δ34S of molybdenum reflects larger negative values. In the structure model image, Sr-Nd isotope dates is located near the mantle,and is affected by lower crust. All inclusions are gas-liquid two phase inclusions, and the gas phase composition is mainly CO2 and a little with CH4 and N2. The ratio of gas to liquid is between 5% and 45%, and the size is of 3×6~33×20μm. Uniform temperature ranges from 130℃ to 290℃, and is mainly 180~260℃; and the salinity in mainly 3%~6% NaCleqv and 10%~18% NaCleqv, and overall it shows the low temperature and salinity characteristics. The ore-forming materials are provided by magama and strata together.

15 citations

Journal ArticleDOI
TL;DR: An origin of the Tinaquillo Peridotite Complex in northern Venezuela, and a model for the tectonic framework of the boundary zone between the southern Caribbean Plate margin and the South American Plate (SAP) during Late Jurassic to Mid-Cretaceous time are developed using newly measured Sr, Nd, Pb and Hf isotopic compositions as well as major and trace element geochemistry for some hornblendite veins and their spinel peridotsite host rocks as discussed by the authors.
Abstract: An origin of the Tinaquillo Peridotite Complex in northern Venezuela, and a model for the tectonic framework of the boundary zone between the southern Caribbean Plate margin and the South American Plate (SAP) during Late Jurassic to Mid-Cretaceous time are developed using newly measured Sr, Nd, Pb and Hf isotopic compositions as well as major and trace element geochemistry for some hornblendite veins and their spinel peridotite host rocks. Depleted geochemical characteristics, principally major element concentrations, and Nd and Hf isotopes (e.g., eNd = + 27; eHf = +50; ca. 3.4 Ga-Nd model age) of the Tinaquillo peridotites suggest a genetic link between this complex and the Guiana Shield farther to the south within Venezuela. Scattered zones within the Tinaquillo peridotite were overprinted by what we interpret as channelized hydrous fluids (<∼3%) derived from the eastward-dipping subduction of the Farallon Plate beneath the SAP in the Late Jurassic, leading to modification of the original Sr, Nd and Hf isotopic compositions as well as the incompatible element concentrations. The hornblendite veins have Sr, Nd, Pb and Hf isotopic compositions, falling within the range of present-day Pacific/Atlantic MORB, but trace element abundance patterns with combinations of arc- and MORB-like characteristics. These results rule out the possibility of local melting of the host peridotites to produce magmas from which the hornblendite veins formed. We suggest that during inception of the westward-dipping subduction of the Protocaribbean Plate immediately following polarity reversal in the Mid-Cretaceous, melts infiltrated the mantle lithosphere and produced the veins.

15 citations

01 Jan 1992
TL;DR: In this article, aphyric and nonvesicular Site 800 alkalic dolerite sills are all well-evolved mineralogically and chemically, being mainly of hawaiite composition, and are similar to ocean island basalts.
Abstract: On the basis of their respective eruptive environments and chemical characteristics, alkalic dolerite sills from the northern Pigafetta Basin (Site 800) and tholeiitic pillow lavas from the Mariana Basin (Site 802) sampled during Ocean Drilling Program Leg 129 are considered to represent examples of the widespread mid-Cretaceous volcanic event in the western Pacific. Both groups of basic rocks feature mild, low-grade, anoxic smectite-celadonite-carbonate-pyrite alteration; late-stage oxidation is very limited in extent, with the exception of the uppermost sill unit at Site 800. The aphyric and nonvesicular Site 800 alkalic dolerite sills are all well-evolved mineralogically and chemically, being mainly of hawaiite composition, and are similar to ocean island basalts. They are characterized by high contents of incompatible elements (for example, 300-400 ppm Zr), well-fractionated rare earth element patterns ([La/Yb]N 18-21) and HIMU isotopic characters. They probably represent deep-sea, lateral, intrusive off-shoots from nearby seamounts of similar age. The olivine-plagioclase ± clinopyroxene phyric tholeiitic pillow lavas and thin flows of Site 802 are nonvesicular and quench-textured throughout. Relative to normal-type mid-ocean ridge basalt, they are enriched in large-ion-lithophile elements, exhibit flat (unfractionated) rare earth element patterns and have distinctive (lower) Zr/Nb, Zr/Ta, La/Ta, and Hf/Th ratios. Overall they are compositionally and isotopically similar to the mid-Cretaceous tholeiites of the Nauru basin and the Ontong-Java and Manihiki plateaus. The Site 802 tholeiites differ from the thickened crustal segments of the oceanic plateaus, however, in apparently representing only a thin veneer over the local basement in an off-axis environment.

15 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20237
202216
202157
202056
201960
201851