Topic
Epidote
About: Epidote is a research topic. Over the lifetime, 1328 publications have been published within this topic receiving 27940 citations.
Papers published on a yearly basis
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Papers
TL;DR: In this paper, the authors made a comprehensive investigation on allanite U-Th-Pb chronology using secondary ion mass spectrometry (SIMS) and five allanites with variable elemental compositions and common lead concentrations have been used.
Abstract: Allanite, an epidote group mineral, occurs as a common accessory mineral in igneous, metamorphic rocks and hydrothermal deposits. It contains radioactive elements Th and U, making it a valuable U–Th–Pb geochronometer for various geological processes. Due to the structural and compositional complexity of allanite, in situ dating method is a better choice when the allanite is heterogeneous or has crystallized in multi-stage events. The wide variation of chemical compositions, however, raises the potential for matrix effects and complicates the use of in situ methods for allanite U–Th–Pb chronology. To address this issue, we made a comprehensive investigation on allanite U–Th–Pb chronology using Secondary Ion Mass Spectrometry (SIMS). Five allanite samples (CAP, Daibosatsu, SQ-51, Toba OTT, TARA allanite) with variable elemental compositions and common lead concentrations have been used. Allanites with variations in FeO (from 12.8 to 16.1 wt%) and similar ThO2 contents (around 1–2%) do not show significant matrix effects, as suggested by a previous study. While, obvious changes in calibration parameters (UO2+/U+, ThO2+/Th+) were noticed for allanites with a large range of Th contents (from 300 ppm to 2.0 wt%). By employing power law relationships between Pb+/U+versus UO2+/U+, Pb+/Th+versus ThO2+/Th+ with suitable exponentials, we do not observe obvious matrix effects with ThO2 concentrations variations. This study demonstrates that allanite can be a good geochronometer for multi-stage mineralization of hydrothermal deposits, providing valuable complementary information to zircon and monazite.
609 citations
TL;DR: In this article, neutral-pH alteration is divided into four zones on the basis of key clay minerals, and two subzones are defined by calc-silicates, and the four main zones of acid alteration are: kaolinite (ambient to 120°C), dickite ± kaolite (120, 200, 200) and pyrophyllite ± illite (230,320°C).
523 citations
TL;DR: A study of the distribution of lanthanide rare earths in a granodiorite from the eastern Peninsular Ranges batholith, southern California, reveals that a large fraction of the REE in this rock resides in the accessory phases sphene and allanite as discussed by the authors.
517 citations
TL;DR: In this paper, a near-isothermal decompression clockwise P-T path for the Mayuan metamorphic assemblage in the Cathaysia and Yangtze blocks is proposed.
Abstract: The Mayuan assemblage in the Cathaysia Block, Southeast China, consists of felsic paragneiss, pelitic schist, greenschist, amphibolite, marble, calcsilicate, and quartzite that underwent three episodes of deformation (D1-D3) and four episodes of metamorphism (M1-M4) in the early Neoproterozoic. The M1 assemblage consists of mineral inclusions defining an early foliation (S1) within porphyroblasts, represented by chlorite muscovite biotite plagioclase quartz in pelitic schist and actinolite chlorite epidote albite quartz enclosed in amphibolite. M2 coincides with the development of the regional schistosity (S2) and represents the formation of the porphyroblasts and growth of matrix minerals, resulting in development of prograde metamorphic zones (chlorite-biotite, garnet, staurolite, and kyanite zones). M3 is simultaneous with the third phase of deformation (D3) and produced sillimanite-bearing mineral assemblages in pelitic schist and hornblende-bearing assemblages in amphibo- lite. The last metamorphic episode M4 gave rise to the retrogressive assemblage chlorite muscovite in pelitic rock and actinolite chlorite epidote in amphibolite. The sequence of mineral assemblages and history of metamorphic reactions built from the petrogenetic grid of pelites suggest a near-isothermal decompression clockwise P-T path for the Mayuan pelitic schists. Using the TWEEQU software program, the garnet-biotite thermometer and garnet- muscovite-biotite-plagioclase barometer yield P-T conditions for M1 of 5.5 to 6.0 kb and 450° to 500°C and conditions for the garnet, staurolite, and kyanite zones of M2 of 6.0 to 7.0 kb and 550° to 600°C, 6.0 to 7.5 kb and 600°C and 11.0 to 11.5 kb and 600°C. The P-T conditions of M3 were estimated at 570° to 625°C and 4.0 to 4.5 kb using the muscovite-biotite thermometer and hornblende-plagioclase geothermo- barometer. The garnet-chlorite thermometer yields temperatures of 300° to 400°C for M4, but the pressures of M4 cannot be quantitatively estimated because of the lack of a suitable geobarometer. These P-T estimates also define an near- isothermal decompression clockwise P-T path, which is involved in initial crustal thickening followed by rapid exhumation and final cooling, and is related to amalgamation of the Cathaysia and Yangtze Blocks to form the South China craton.
385 citations
TL;DR: In this article, it was shown that epidote crystallized as a relatively late but magmatic mineral that formed through reaction with hornblende in the presence of a melt phase, which concur with experimental data on crystallization of epidote from synthetic granodiorite at 8 kbar total pressure.
Abstract: Epidote is a major magmatic mineral in tonalite and granodiorite in a belt coextensive with the Mesozoic accreted terranes between northern California and southeastern Alaska. Textural and chemical evidence indicates that epidote crystallized as a relatively late but magmatic mineral that formed through reaction with hornblende in the presence of a melt phase. The observed relations concur with experimental data on crystallization of epidote from synthetic granodiorite at 8 kbar total pressure. Plutonic rocks bearing magmatic epidote must have formed under moderately high pressures, corresponding to lower crustal depths, under fairly oxidizing conditions.
356 citations
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Performance Metrics
| Year | Papers |
|---|---|
| 2025 | 12 |
| 2024 | 22 |
| 2023 | 89 |
| 2022 | 106 |
| 2021 | 56 |
| 2020 | 51 |