Cerium and Ytrium in apatite as records of magmatic processes: Insight into fractional crystallization, magma mingling and fluid saturation

Geochemistry ◽  
2022 ◽  
pp. 125864
Author(s):  
Arkadiusz Przybyło ◽  
Anna Pietranik ◽  
Grzegorz Zieliński
Keyword(s):  
Fractional Crystallization ◽  
Magma Mingling ◽  
Fluid Saturation ◽  
Magmatic Processes ◽  
Insight Into

scholarly journals Mantle Melting and Magmatic Processes Under La Picada Stratovolcano (CSVZ, Chile)

2019 ◽  
Vol 60 (5) ◽  
pp. 907-944 ◽  
Author(s):  
Jacqueline Vander Auwera ◽  
Olivier Namur ◽  
Adeline Dutrieux ◽  
Camilla Maya Wilkinson ◽  
Morgan Ganerød ◽  
...  
Keyword(s):  
Fractional Crystallization ◽  
Geochemical Data ◽  
Upper Crust ◽  
Volcanic Zone ◽  
Nazca Plate ◽  
Southern Volcanic Zone ◽  
Magmatic Processes ◽  
Crystal Accumulation ◽  
Primary Magmas ◽  
Differentiation Trend

Abstract Where and how arc magmas are generated and differentiated are still debated and these questions are investigated in the context of part of the Andean arc (Chilean Southern Volcanic Zone) where the continental crust is thin. Results are presented for the La Picada stratovolcano (41°S) that belongs to the Central Southern Volcanic Zone (CSVZ) (38°S–41·5°S, Chile) which results from the subduction of the Nazca plate beneath the western margin of the South American continent. Forty-seven representative samples collected from different units of the volcano define a differentiation trend from basalt to basaltic andesite and dacite (50·9 to 65·6 wt % SiO2). This trend straddles the tholeiitic and calc-alkaline fields and displays a conspicuous compositional Daly Gap between 57·0 and 62·7 wt % SiO2. Interstitial, mostly dacitic, glass pockets extend the trend to 76·0 wt % SiO2. Mineral compositions and geochemical data indicate that differentiation from the basaltic parent magmas to the dacites occurred in the upper crust (∼0·2 GPa) with no sign of an intermediate fractionation stage in the lower crust. However, we have currently no precise constraint on the depth of differentiation from the primary magmas to the basaltic parent magmas. Stalling of the basaltic parent magmas in the upper crust could have been controlled by the occurrence of a major crustal discontinuity, by vapor saturation that induced volatile exsolution resulting in an increase of melt viscosity, or by both processes acting concomitantly. The observed Daly Gap thus results from upper crustal magmatic processes. Samples from both sides of the Daly Gap show contrasting textures: basalts and basaltic andesites, found as lavas, are rich in macrocrysts, whereas dacites, only observed in crosscutting dykes, are very poor in macrocrysts. Moreover, modelling of the fractional crystallization process indicates a total fractionation of 43% to reach the most evolved basaltic andesites. The Daly Gap is thus interpreted as resulting from critical crystallinity that was reached in the basaltic andesites within the main storage region, precluding eruption of more evolved lavas. Some interstitial dacitic melt was extracted from the crystal mush and emplaced as dykes, possibly connected to small dacitic domes, now eroded away. In addition to the overall differentiation trend, the basalts to basaltic andesites display variable MgO, Cr and Ni contents at a given SiO2. Crystal accumulation and high pressure fractionation fail to predict this geochemical variability which is interpreted as resulting from variable extents of fractional crystallization. Geothermobarometry using recalculated primary magmas indicates last equilibration at about 1·3–1·5 GPa and at a temperature higher than the anhydrous peridotite solidus, pointing to a potential role of decompression melting. However, because the basalts are enriched in slab components and H2O compared to N-MORB, wet melting is highly likely.

Gassmann's equation and fluid‐saturation effects on seismic velocities

Geophysics ◽  
2004 ◽  
Vol 69 (2) ◽  
pp. 398-405 ◽  
Author(s):  
De‐hua Han ◽  
Michael L. Batzle
Keyword(s):  
Upper And Lower Bounds ◽  
Fluid Substitution ◽  
Seismic Velocities ◽  
Critical Porosity ◽  
Fluid Saturation ◽  
Gassmann’S Equation ◽  
Physical Insight ◽  
Velocity Changes ◽  
Saturation Effects ◽  
Insight Into

Gassmann's (1951) equations commonly are used to predict velocity changes resulting from different pore‐fluid saturations. However, the input parameters are often crudely estimated, and the resulting estimates of fluid effects can be unrealistic. In rocks, parameters such as porosity, density, and velocity are not independent, and values must be kept consistent and constrained. Otherwise, estimating fluid substitution can result in substantial errors. We recast the Gassmann's relations in terms of a porosity‐dependent normalized modulus Kn and the fluid sensitivity in terms of a simplified gain function G. General Voigt‐Reuss bounds and critical porosity limits constrain the equations and provide upper and lower bounds of the fluid‐saturation effect on bulk modulus. The “D” functions are simplified modulus‐porosity relations that are based on empirical porosity‐velocity trends. These functions are applicable to fluid‐substitution calculations and add important constraints on the results. More importantly, the simplified Gassmann's relations provide better physical insight into the significance of each parameter. The estimated moduli remain physical, the calculations are more stable, and the results are more realistic.

scholarly journals Reddish Metagranites from the Gennargentu Igneous Complex (Sardinia, Italy): Insight into Metasomatism Induced by Magma Mingling

2013 ◽  
Vol 54 (5) ◽  
pp. 839-859 ◽  
Author(s):  
Mario Gaeta ◽  
Andrea Giuliani ◽  
Simona Perilla ◽  
Valeria Misiti
Keyword(s):  
Magma Mingling ◽  
Igneous Complex ◽  
Insight Into

New Insight into the Petrophysical Characterization of Shales with Different Fluid Saturation States Based on Nuclear Magnetic Resonance Experiments

2020 ◽  
Vol 34 (5) ◽  
pp. 5599-5610
Author(s):  
Xin Zeng ◽  
Jianmeng Sun ◽  
Weichao Yan ◽  
Ruikang Cui ◽  
Weiguo Yuan ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Fluid Saturation ◽  
Insight Into ◽  
Nuclear Magnetic

scholarly journals Insight into the Pore Structures and Its Impacts on Movable Fluid in Tight Sandstones

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Dazhong Ren ◽  
Fu Yang ◽  
Rongxi Li ◽  
Desheng Zhou ◽  
Dengke Liu ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Pore Structure ◽  
Water Film ◽  
Gas Content ◽  
Pore Throat ◽  
Gas Field ◽  
Fluid Saturation ◽  
Western Area ◽  
Flow Features ◽  
Insight Into

Both the characteristics of pore structure and movable fluid are significant properties in controlling the flow regularity in pores in tight sandstones. However, the governing factors that affect the fluid flow features will still be a myth. In our research, the western area of the Sulige gas field was chosen as the research region, and various kinds of experiments were conducted. Three reservoir groups, including intergranular-dissolved pore type, dissolved-intercrystalline pore type, and pore plus microcracks type were identified on the basis of pore development features. The results suggest that the intergranular-dissolved pore type has a more prominent influence on the high movable fluid saturation and larger pores. Both large throat sizes and homogeneous pore-throat degree demonstrate high movable fluid saturation. The increment of the thickness of water-film resulted from hydrophilic enhancement, indicating that an increased hydrophilic will decrease the movable fluid saturation and block the throats. The reservoirs of different pore combination types are closely related to the gas content of the reservoir.

Petrogenesis of the Leo Lake and Lyndhurst plutons, Frontenac terrane, Central Metasedimentary Belt, southeastern Ontario, Canada

2007 ◽  
Vol 44 (1) ◽  
pp. 107-126 ◽  
Author(s):  
T A Grammatikopoulos ◽  
A H Clark ◽  
D A Archibald
Keyword(s):  
Spatial Distribution ◽  
Fractional Crystallization ◽  
Crystallization Process ◽  
Geochemical Data ◽  
Textural Features ◽  
Olivine Gabbro ◽  
Magma Mingling

The 1167 ± 2 Ma Leo Lake pluton, located at the southern part of the Frontenac terrane in Central Metasedimentary Belt of southeastern Ontario, is a bimodal pluton that is dominated by olivine gabbro, gabbro, syenite, and lesser monzonite. The adjoining 1166 ± 3 Ma Lyndhurst pluton is composed of syenite and granite, and exhibits magma mingling. Even though geochemical data from both plutons suggest fractional crystallization as the main crystallization process, magma mingling is evident in the Lyndhurst pluton. Hornblende from the Leo Lake syenite yields a 40Ar–39Ar age of 1120 ± 6 Ma and titanite from the adjacent St. Lawrence skarn yields a U–Pb age of 1147 ± 8 Ma. The 40Ar–39Ar age indicates that the pluton cooled to 550 °C at a rate of ca. <2 °C/Ma following emplacement. The two plutons are similar in petrology to several other granitic, syenitic, and monzonitic intrusions of the Frontenac suite in the Frontenac terrane. Moreover, the spatial distribution, textural features, and geochemistry indicate that the plutons are coeval. The present data indicate that the two plutons may have been produced from evolved mantle-derived melts, and may have assimilated varying proportions of crustal melts.

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