The role of crustal and eruptive processes versus source variations in controlling the oxidation state of iron in Central Andean magmas

The composition of the continental crust is closely tied to subduction zone magmatism. Elevated oxygen fugacity (fO₂) plays a central role in fostering crystallization of oxide minerals and thereby aids in generating the calc-alkaline trend of iron depletion that characterizes the continents. Along continental margins, arc magmas erupt through continental crust and often undergo extensive differentiation that may modify magmatic fO₂. The importance of the subducting slab and mantle wedge relative to the effects of this differentiation on the fO₂ recorded by continental arc magmas remains relatively unconstrained. Here, we focus on the effect of differentiation on magmatic fO₂ using a suite of 14 samples from the Central Volcanic Zone (CVZ) of the Andes where the continental crust is atypically thick (60–80 km). The samples range in composition from ∼55 to 74 wt% SiO₂ and represent the Neogene history of the arc. Samples are basaltic andesite to rhyolite and span a range of radiogenic isotopic compositions (⁸⁷Sr/⁸⁶Sr = ∼0.705–0.712) that represent 30 to 100% crustal assimilation. We use several proxies to estimate the fO₂ recorded by lavas, pumice, and scoria: (1) whole rock Fe³⁺/ΣFe ratios, (2) Fe³⁺+/ΣFe ratios in quartz-hosted melt inclusions, and (3) Fe–Ti oxide oxygen-barometry. Comparison of the fO₂ calculated from bulk Fe³⁺/ΣFe ratios (post-eruptive) with that derived from Fe–Ti oxides or melt inclusion Fe³⁺/ΣFe ratios (pre-eruptive), enables us to quantify the effect of syn- or post-eruptive alteration, and to select rocks for bulk analysis appropriate for the determination of pre-eruptive magmatic fO₂ using a strict criterion developed here. Across our sample suite, and in context with samples from the literature, we do not find evidence for systematic oxidation due to crystal fractionation or crustal contamination. Less evolved samples, ranging from 55 to 61 wt% SiO₂, record a range of >3 orders of magnitude in fO₂, spanning the fO₂ range recorded by all samples in our suite. Among these less evolved magmas, we find that those erupted from volcanic centers located closer to the trench, closer to the Benioff Zone, and with more geochemical evidence of subducted components in the mantle source (elevated La/Nb) result in magmas that record systematically higher fO₂. We conclude that the slab/mantle source can exert greater control on magmatic fO₂ than processes occurring in even the thickest continental crust. Thus, the fO₂ of arc magmas, and hence their calc-alkaline nature, may be inherited from the mantle.Keywords: oxygen fugacity, wet chemistry, subduction, crustal assimilation, Central Andean volcanic zoneKeywords: oxygen fugacity, wet chemistry, subduction, crustal assimilation, Central Andean volcanic zon

“Telling me not to worry…” Hyperscanning and Neural Dynamics of Emotion Processing During Guided Imagery and Music

To analyze how emotions and imagery are shared, processed and recognized in Guided Imagery and Music, we measured the brain activity of an experienced therapist (“Guide”) and client (“Traveler”) with dual-EEG in a real therapy session about potential death of family members. Synchronously with the EEG, the session was video-taped and then micro-analyzed. Four raters identified therapeutically important moments of interest (MOI) and no-interest (MONI) which were transcribed and annotated. Several indices of emotion- and imagery-related processing were analyzed: frontal and parietal alpha asymmetry, frontal midline theta, and occipital alpha activity. Session ratings showed overlaps across all raters, confirming the importance of these MOIs, which showed different cortical activity in visual areas compared to resting-state. MOI 1 was a pivotal moment including an important imagery with a message of hope from a close family member, while in the second MOI the Traveler sent a message to an unborn baby. Generally, results seemed to indicate that the emotions of Traveler and Guide during important moments were not positive, pleasurably or relaxed when compared to resting-state, confirming both were dealing with negative emotions and anxiety that had to be contained in the interpersonal process. However, the temporal dynamics of emotion-related markers suggested shifts in emotional valence and intensity during these important, personally meaningful moments; for example, during receiving the message of hope, an increase of frontal alpha asymmetry was observed, reflecting increased positive emotional processing. EEG source localization during the message suggested a peak activation in left middle temporal gyrus. Interestingly, peaks in emotional markers in the Guide partly paralleled the Traveler's peaks; for example, during the Guide's strong feeling of mutuality in MOI 2, the time series of frontal alpha asymmetries showed a significant cross-correlation, indicating similar emotional processing in Traveler and Guide. Investigating the moment-to-moment interaction in music therapy showed how asymmetry peaks align with the situated cognition of Traveler and Guide along the emotional contour of the music, representing the highs and lows during the therapy process. Combining dual-EEG with detailed audiovisual and qualitative data seems to be a promising approach for further research into music therapy

A Case Study in the Bonny Method of Guided Imagery and Music (BMGIM)

B1 - Research Book Chapter

Healing an inflamed body: The Bonny Method of GIM in treating rheumatoid arthritis

B1 - Research Book Chapter

Phenomenological Inquiry

B1 - Research Book Chapter

GrockeRoleCrustalEruptiveAppendix A.pdf

The composition of the continental crust is closely tied to subduction zone magmatism. Elevated oxygen fugacity (fO₂) plays a central role in fostering crystallization of oxide minerals and thereby aids in generating the calc-alkaline trend of iron depletion that characterizes the continents. Along continental margins, arc magmas erupt through continental crust and often undergo extensive differentiation that may modify magmatic fO₂. The importance of the subducting slab and mantle wedge relative to the effects of this differentiation on the fO₂ recorded by continental arc magmas remains relatively unconstrained. Here, we focus on the effect of differentiation on magmatic fO₂ using a suite of 14 samples from the Central Volcanic Zone (CVZ) of the Andes where the continental crust is atypically thick (60–80 km). The samples range in composition from ∼55 to 74 wt% SiO₂ and represent the Neogene history of the arc. Samples are basaltic andesite to rhyolite and span a range of radiogenic isotopic compositions (⁸⁷Sr/⁸⁶Sr = ∼0.705–0.712) that represent 30 to 100% crustal assimilation. We use several proxies to estimate the fO₂ recorded by lavas, pumice, and scoria: (1) whole rock Fe³⁺/ΣFe ratios, (2) Fe³⁺+/ΣFe ratios in quartz-hosted melt inclusions, and (3) Fe–Ti oxide oxygen-barometry. Comparison of the fO₂ calculated from bulk Fe³⁺/ΣFe ratios (post-eruptive) with that derived from Fe–Ti oxides or melt inclusion Fe³⁺/ΣFe ratios (pre-eruptive), enables us to quantify the effect of syn- or post-eruptive alteration, and to select rocks for bulk analysis appropriate for the determination of pre-eruptive magmatic fO₂ using a strict criterion developed here. Across our sample suite, and in context with samples from the literature, we do not find evidence for systematic oxidation due to crystal fractionation or crustal contamination. Less evolved samples, ranging from 55 to 61 wt% SiO₂, record a range of >3 orders of magnitude in fO₂, spanning the fO₂ range recorded by all samples in our suite. Among these less evolved magmas, we find that those erupted from volcanic centers located closer to the trench, closer to the Benioff Zone, and with more geochemical evidence of subducted components in the mantle source (elevated La/Nb) result in magmas that record systematically higher fO₂. We conclude that the slab/mantle source can exert greater control on magmatic fO₂ than processes occurring in even the thickest continental crust. Thus, the fO₂ of arc magmas, and hence their calc-alkaline nature, may be inherited from the mantle.Keywords: crustal assimilation, Central Andean volcanic zone, wet chemistry, oxygen fugacity, subductio

The role of crustal and eruptive processes versus source variations in controlling the oxidation state of iron in Central Andean magmas

The composition of the continental crust is closely tied to subduction zone magmatism. Elevated oxygen fugacity (fO2) plays a central role in fostering crystallization of oxide minerals and thereby aids in generating the calc-alkaline trend of iron depletion that characterizes the continents. Along continental margins, arc magmas erupt through continental crust and often undergo extensive differentiation that may modify magmatic fO2. The importance of the subducting slab and mantle wedge relative to the effects of this differentiation on the fO2 recorded by continental arc magmas remains relatively unconstrained. Here, we focus on the effect of differentiation on magmatic fO2 using a suite of 14 samples from the Central Volcanic Zone (CVZ) of the Andes where the continental crust is atypically thick (60-80 km). The samples range in composition from ~55 to 74 wt% SiO2 and represent the Neogene history of the arc. Samples are basaltic andesite to rhyolite and span a range of radiogenic isotopic compositions (87Sr/86Sr = ~0.705-0.712) that represent 30 to 100% crustal assimilation. We use several proxies to estimate the fO2 recorded by lavas, pumice, and scoria: (1) whole rock Fe3+/σFe ratios, (2) Fe3+/σFe ratios in quartz-hosted melt inclusions, and (3) Fe-Ti oxide oxygen-barometry. Comparison of the fO2 calculated from bulk Fe3+/σFe ratios (post-eruptive) with that derived from Fe-Ti oxides or melt inclusion Fe3+/σFe ratios (pre-eruptive), enables us to quantify the effect of syn- or post-eruptive alteration, and to select rocks for bulk analysis appropriate for the determination of pre-eruptive magmatic fO2 using a strict criterion developed here. Across our sample suite, and in context with samples from the literature, we do not find evidence for systematic oxidation due to crystal fractionation or crustal contamination. Less evolved samples, ranging from 55 to 61 wt% SiO2, record a range of \u3e3 orders of magnitude in fO2, spanning the fO2 range recorded by all samples in our suite. Among these less evolved magmas, we find that those erupted from volcanic centers located closer to the trench, closer to the Benioff Zone, and with more geochemical evidence of subducted components in the mantle source (elevated La/Nb) result in magmas that record systematically higher fO2. We conclude that the slab/mantle source can exert greater control on magmatic fO2 than processes occurring in even the thickest continental crust. Thus, the fO2 of arc magmas, and hence their calc-alkaline nature, may be inherited from the mantle

GrockeRoleCrustalEruptive.pdf

The composition of the continental crust is closely tied to subduction zone magmatism. Elevated oxygen fugacity (fO₂) plays a central role in fostering crystallization of oxide minerals and thereby aids in generating the calc-alkaline trend of iron depletion that characterizes the continents. Along continental margins, arc magmas erupt through continental crust and often undergo extensive differentiation that may modify magmatic fO₂. The importance of the subducting slab and mantle wedge relative to the effects of this differentiation on the fO₂ recorded by continental arc magmas remains relatively unconstrained. Here, we focus on the effect of differentiation on magmatic fO₂ using a suite of 14 samples from the Central Volcanic Zone (CVZ) of the Andes where the continental crust is atypically thick (60–80 km). The samples range in composition from ∼55 to 74 wt% SiO₂ and represent the Neogene history of the arc. Samples are basaltic andesite to rhyolite and span a range of radiogenic isotopic compositions (⁸⁷Sr/⁸⁶Sr = ∼0.705–0.712) that represent 30 to 100% crustal assimilation. We use several proxies to estimate the fO₂ recorded by lavas, pumice, and scoria: (1) whole rock Fe³⁺/ΣFe ratios, (2) Fe³⁺+/ΣFe ratios in quartz-hosted melt inclusions, and (3) Fe–Ti oxide oxygen-barometry. Comparison of the fO₂ calculated from bulk Fe³⁺/ΣFe ratios (post-eruptive) with that derived from Fe–Ti oxides or melt inclusion Fe³⁺/ΣFe ratios (pre-eruptive), enables us to quantify the effect of syn- or post-eruptive alteration, and to select rocks for bulk analysis appropriate for the determination of pre-eruptive magmatic fO₂ using a strict criterion developed here. Across our sample suite, and in context with samples from the literature, we do not find evidence for systematic oxidation due to crystal fractionation or crustal contamination. Less evolved samples, ranging from 55 to 61 wt% SiO₂, record a range of >3 orders of magnitude in fO₂, spanning the fO₂ range recorded by all samples in our suite. Among these less evolved magmas, we find that those erupted from volcanic centers located closer to the trench, closer to the Benioff Zone, and with more geochemical evidence of subducted components in the mantle source (elevated La/Nb) result in magmas that record systematically higher fO₂. We conclude that the slab/mantle source can exert greater control on magmatic fO₂ than processes occurring in even the thickest continental crust. Thus, the fO₂ of arc magmas, and hence their calc-alkaline nature, may be inherited from the mantle.Keywords: Central Andean volcanic zone, subduction, crustal assimilation, oxygen fugacity, wet chemistr

GrockeRoleCrustalEruptiveAppendixATable1-3.xlsx

The composition of the continental crust is closely tied to subduction zone magmatism. Elevated oxygen fugacity (fO₂) plays a central role in fostering crystallization of oxide minerals and thereby aids in generating the calc-alkaline trend of iron depletion that characterizes the continents. Along continental margins, arc magmas erupt through continental crust and often undergo extensive differentiation that may modify magmatic fO₂. The importance of the subducting slab and mantle wedge relative to the effects of this differentiation on the fO₂ recorded by continental arc magmas remains relatively unconstrained. Here, we focus on the effect of differentiation on magmatic fO₂ using a suite of 14 samples from the Central Volcanic Zone (CVZ) of the Andes where the continental crust is atypically thick (60–80 km). The samples range in composition from ∼55 to 74 wt% SiO₂ and represent the Neogene history of the arc. Samples are basaltic andesite to rhyolite and span a range of radiogenic isotopic compositions (⁸⁷Sr/⁸⁶Sr = ∼0.705–0.712) that represent 30 to 100% crustal assimilation. We use several proxies to estimate the fO₂ recorded by lavas, pumice, and scoria: (1) whole rock Fe³⁺/ΣFe ratios, (2) Fe³⁺+/ΣFe ratios in quartz-hosted melt inclusions, and (3) Fe–Ti oxide oxygen-barometry. Comparison of the fO₂ calculated from bulk Fe³⁺/ΣFe ratios (post-eruptive) with that derived from Fe–Ti oxides or melt inclusion Fe³⁺/ΣFe ratios (pre-eruptive), enables us to quantify the effect of syn- or post-eruptive alteration, and to select rocks for bulk analysis appropriate for the determination of pre-eruptive magmatic fO₂ using a strict criterion developed here. Across our sample suite, and in context with samples from the literature, we do not find evidence for systematic oxidation due to crystal fractionation or crustal contamination. Less evolved samples, ranging from 55 to 61 wt% SiO₂, record a range of >3 orders of magnitude in fO₂, spanning the fO₂ range recorded by all samples in our suite. Among these less evolved magmas, we find that those erupted from volcanic centers located closer to the trench, closer to the Benioff Zone, and with more geochemical evidence of subducted components in the mantle source (elevated La/Nb) result in magmas that record systematically higher fO₂. We conclude that the slab/mantle source can exert greater control on magmatic fO₂ than processes occurring in even the thickest continental crust. Thus, the fO₂ of arc magmas, and hence their calc-alkaline nature, may be inherited from the mantle.Keywords: wet chemistry, Central Andean volcanic zone, subduction, crustal assimilation, oxygen fugacit