?Calcic amphibole equilibria and a new amphibole-plagioclase geothermometer?: Reply to the comments of Hammarstrom and Zen, and Rutherford and Johnson

1992 ◽  
Vol 111 (2) ◽  
pp. 269-272 ◽  
Author(s):  
Jonathan D. Blundy ◽  
Timothy J. B. Holland
Keyword(s):  
Calcic Amphibole

Application and reliability of calcic amphibole thermobarometry as inferred from calc-alkaline products of active geothermal areas in the Andes

2018 ◽  
Vol 358 ◽  
pp. 58-76 ◽  
Author(s):  
Andrea Gorini ◽  
Filippo Ridolfi ◽  
Filippo Piscaglia ◽  
Marco Taussi ◽  
Alberto Renzulli
Keyword(s):  
Calc Alkaline ◽  
The Andes ◽  
Calcic Amphibole

Analysis of Baseline and Perimeter Air Monitoring Data from the Calaveras Dam Replacement Project (CDRP), Fremont, California

2020 ◽  
Author(s):  
Bradley Erskine ◽  
Mark Bailey
Keyword(s):  
Wind Direction ◽  
Soil Disturbance ◽  
Soil Samples ◽  
Monitoring Data ◽  
Local Source ◽  
Amphibole Composition ◽  
Calcic Amphibole ◽  
Several Variables ◽  
Index 2 ◽  
Time Of Year

<p>This paper presents the results of 810 pre-project baseline samples collected over four years (2010-2011), and 7,210 offsite (ambient) and 14,314 perimeter samples collected over 7 years (2012-2018) during the CDRP project. The principal asbestos particles were chrysotile from serpentinite, and glaucophane-winchite amphibole from blueschist. The baseline data showed that asbestos concentrations measured at each station are not representative of a regional average background, rather, they reflect contributions from several variables such as: location on or near NOA-containing units, wind direction, intensity of localized soil disturbance, and time of year. The data shows that baseline sampling prior to a project cannot be used as a measure of “background” during the project. The analysis of amphibole composition in air and rock/soil samples was applied to differentiate local source impacts from the primary CDRP asbestos emissions. Of particular value was the application of the calcic-amphibole to total amphibole ratio (Ca index) measured during ABS sampling and comparison with the ratios measured in the samples. This analysis delineated three primary amphibole sources: 1) alluvium in the Sunol Valley with a high Ca index, 2) imported road surfacing material with a moderate Ca index, and 3) blueschist with a low Ca index. When the data was sorted by wind direction, the analysis showed that the contribution of CDRP-generated asbestos to monitoring stations was significant near the point of disturbance only, and did not significantly impact offsite stations that were located at or near sensitive receptors. The asbestos measured at the offsite stations were correlated with local geologic units. The analysis verified that the CDRP emissions were well below the project-specific risk-based thresholds established for the CDRP project, documenting that the offsite receptors were not exposed to an adverse risk by CDRP activities.</p>

scholarly journals Amp-TB2: An Updated Model for Calcic Amphibole Thermobarometry

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 324
Author(s):  
Filippo Ridolfi
Keyword(s):  
Single Phase ◽  
Graphical Representation ◽  
Calibration Data ◽  
Magma Chambers ◽  
Calcic Amphibole ◽  
Physico Chemical ◽  
Planetary Processes ◽  
User Friendly ◽  
Melt Composition ◽  
Selection Of

Amphibole (Amp) plays a crucial role in the study of several earth and planetary processes. One of its most common applications is in thermobarometry, especially for volcanic-magmatic systems. However, many thermobarometers require the input of melt composition, which is not always available in volcanic products (e.g., partially crystallized melts or devitrified glasses), or show rather high errors for characterizing the depth of magma chambers. In this work, a new version of amphibole thermobarometry based on the selection of recently published high-quality experimental data is reported. It is valid for Mg-rich calcic amphiboles in magmatic equilibrium with calc-alkaline or alkaline melts across a wide P-T range (up to 2200 MPa and 1130 °C) and presents the advantage of being a single-phase model with relatively low errors (P ±12%, T ±22 °C, logfO2 ±0.3, H2O in the melt ±14%). A user-friendly spreadsheet (Amp-TB2.xlsx) for calculating the physico-chemical parameters from the composition of natural amphiboles is also reported. It gives warnings whenever the input composition is incorrect or diverges from that of the calibration data and includes diagrams for an easy graphical representation of the results.

Diopsidites from a Neoproterozoic–Cambrian suture in southern India

2010 ◽  
Vol 147 (5) ◽  
pp. 777-788 ◽  
Author(s):  
M. SANTOSH ◽  
V. J. RAJESH ◽  
T. TSUNOGAE ◽  
S. ARAI
Keyword(s):  
Rare Earth ◽  
Subduction Zone ◽  
Rare Earth Element ◽  
Earth Element ◽  
Suture Zone ◽  
Dharwar Craton ◽  
Southern India ◽  
The North ◽  
Calcic Amphibole ◽  
Gondwana Supercontinent

AbstractWe report the occurrence and characteristics of diopsidite dykes and veins from the Palghat-Cauvery Suture Zone (PCSZ) marking the boundary between the Archaean Dharwar craton to the north and the Proterozoic Madurai Block to the south, which is considered as a trace of the Cambrian Gondwana suture zone in southern India. The diopsidites are composed predominantly of coarse crystals of diopside [Mg no. (100 Mg/(Mg+Fetot)) up to 89] surrounded by retrograde calcic amphibole, plagioclase and phlogopite with accessory titanite and calcite. The major, trace and rare earth element characteristics of the diopside crystals suggest their formation in a subduction zone setting. We correlate the petrogenesis of the diopsidites with the tectonics associated with the subduction and closure of the Neoproterozoic Mozambique Ocean prior to the final collisional assembly of the Gondwana supercontinent in Cambrian.

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