The role of mantle-derived magmas in the isotopic evolution of Yellowstone's magmatic system

Mark E. Stelten; Kari M. Cooper; Josh B. Wimpenny; Jorge A. Vazquez; Qing-Zhu Yin

doi:10.1002/2016gc006664

Influence of the Bell-Jar Magma Chamber Geometry on a Caldera Formation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.825.165 ◽

2016 ◽

Vol 825 ◽

pp. 165-169

Author(s):

Michael Somr ◽

Petr Kabele

Keyword(s):

Numerical Modeling ◽

Magma Chamber ◽

Magmatic System ◽

Caldera Formation

The formation of a caldera poses a serious risk for the society and the environment. There are several established processes (mostly dealing with the conditions inside the reservoir), which must take place in order to reach a collapse leading to the caldera. The role of magma chamber geometry is investigated in this paper, exploiting the numerical modeling. The results indicates that the knowledge of the magmatic system dimensions can provide a helpful factor for an assessment of the caldera formation scenario.

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The role of low-temperature 18O exchange in the isotopic evolution of deep subsurface fluids

Chemical Geology ◽

10.1016/j.chemgeo.2020.120027 ◽

2021 ◽

Vol 561 ◽

pp. 120027

Author(s):

Oliver Warr ◽

Thomas Giunta ◽

Tullis C. Onstott ◽

Thomas L. Kieft ◽

Rachel L. Harris ◽

...

Keyword(s):

Low Temperature ◽

Deep Subsurface ◽

Isotopic Evolution

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Understanding the role of accessory minerals in the Sm-Nd isotopic evolution of ancient rocks: An in-situ LA-(MC)-ICP-MS approach

10.5194/egusphere-egu2020-9103 ◽

2020 ◽

Author(s):

Johannes Hammerli

Keyword(s):

Hf Isotope ◽

Nd Isotope ◽

Accessory Minerals ◽

Icp Ms ◽

Isotopic Evolution ◽

Magma Sources ◽

Mantle Reservoir ◽

Isotope System

The long-lived radiogenic isotope systems Lu-Hf and Sm-Nd have been widely used by geochemists to study magma sources and crustal residential times of (igneous) rocks in order to understand how early crust formed and to model the production rate and volume of continental crust on global and regional-scales during the last ~4.4 Ga. However, while throughout most of Earth&#8217;s history Nd and Hf isotope signatures in terrestrial rocks are well correlated due to their very similar geochemical behavior, some of Earth&#8217;s oldest rocks show an apparent inconsistency in their Nd and Hf isotope signatures. While Hf isotopes in early Archean rocks are generally (near) chondritic, Nd isotope signatures can be distinctly super- or sub-chondritic. The super-chondritic Nd isotope values in Eoarchean samples would suggest that these rocks are derived from a mantle reservoir depleted by prior crust extraction. The chondritic Hf isotope values, on the other hand, support a mantle source from which no significant volume of crust had been extracted. While a range of different processes, some of them speculative, might explain this Hf-Nd isotope paradox, recent research [1, 2] has shown that relatively simple, post-magmatic, open-system processes can explain decoupling of the typically correlative Hf-Nd isotope signatures. This talk will focus on the importance of identifying Nd-bearing accessory minerals in (Archean) rocks to understand how the Sm-Nd isotope system is controlled and how in situ isotope and trace element analyses by LA-(MC)-ICP-MS in combination with detailed petrographic observations help to understand when and via which processes the two isotope systems become decoupled. Reconstructing the isotopic evolution of the different isotope systems since formation of the protoliths has important implications for our understanding of early crust formation and questions some of the proposed current models for early crust extraction from the mantle.&#160;[1] Hammerli et al. (2019) Chem. Geol 2; [2] Fisher et al. (2020) EPSL

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The role of magma mixing, identification of mafic magma inputs, and structure of the underlying magmatic system at Mount St. Helens

American Mineralogist ◽

10.2138/am-2018-6555 ◽

2018 ◽

Vol 103 (12) ◽

pp. 1925-1944 ◽

Cited By ~ 8

Author(s):

William P. Leeman ◽

Diane R. Smith

Keyword(s):

Magma Mixing ◽

Mafic Magma ◽

Magmatic System ◽

Mount St Helens

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Isotopic evolution of the mantle: the role of magma mixing

Earth and Planetary Science Letters ◽

10.1016/0012-821x(82)90168-6 ◽

1982 ◽

Vol 57 (1) ◽

pp. 1-12 ◽

Cited By ~ 60

Author(s):

Don L. Anderson

Keyword(s):

Magma Mixing ◽

Isotopic Evolution

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Petrological-geochemical characteristics of lavas, sources and evolution of magmatic melts of the Kazbek neovolcanic center (Greater Caucasus)

Петрология ◽

10.31857/s0869-5903276658-689 ◽

2019 ◽

Vol 27 (6) ◽

pp. 658-689

Author(s):

A. V. Parfenov ◽

V. A. Lebedev ◽

I. V. Chernyshev ◽

G. T. Vashakidze ◽

A. I. Yakushev ◽

...

Keyword(s):

Volcanic Rocks ◽

Geochemical Characteristics ◽

Crustal Assimilation ◽

Magmatic System ◽

Greater Caucasus ◽

Leading Role ◽

Mantle Reservoir ◽

The Common ◽

Geochemical Studies

The results of petrological-geochemical and isotope-geochemical studies of the Late Pleistocene-Holocene lavas of the Kazbek Neovolcanic Center, one of the largest centers of youngest magmatism in the Greater Caucasus, are presented. It has been established that the volcanic rocks of the Kazbek center arise a continuous compositional series basaltic (trachy-)andesites(trachy-)andesitesdacites with a predominance of calc-alkaline intermediate and moderately-acid lavas. The obtained results indicate that the processes of fractional crystallization and mixing of melts had a leading role in the petrogenesis of the rocks. The crustal assimilation was of limited importance; its influence is noticeable only in the rocks of the earliest and late pulses of magmatic activity within the Kazbek center. The common crustal lithologies participated in the assimilation were presented by metamorphosed Jurassic sediments (mainly shales and sandstones), forming the foot of the Kazbek center, and Mesozoic mafic metamorphosed volcanites very rarely. The specific features of AFC processes during the development of the studied magmatic system (including the presence of noticeable amount of water in the melt, the leading role of Amp in the cumulus and the absence of Pl fractionation) led to the appearance of dacitic lavas with geochemical signs of adakites as an evolutional end-member. The volcanic rocks of the Kazbek center are derived from trachybasalt magmas, the source of which was presented by the mantle reservoir of OIB-type. Recent and previously published results of studies of the Neogene-Quaternary magmatism manifested within the Greater Caucasus show that the main petrological and geochemical characteristics of this regional mantle reservoir remained constant from the end of the Miocene to the present time.

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Review of Explosive Hydrovolcanism

Geosciences ◽

10.3390/geosciences10020044 ◽

2020 ◽

Vol 10 (2) ◽

pp. 44 ◽

Cited By ~ 16

Author(s):

Károly Németh ◽

Szabolcs Kósik

Keyword(s):

Energy Transfer ◽

Kinetic Energy ◽

Small Volume ◽

Classification Scheme ◽

Volcanic Eruptions ◽

Magmatic System ◽

Geological Record ◽

Water Interaction ◽

The Past

Hydrovolcanism is a type of volcanism where magma and water interact either explosively or non-explosively. The less frequently used term, hydromagmatism, includes all the processes responsible for magma and water interaction in a magmatic system. Hydrovolcanism is commonly used as a synonym for phreatomagmatism. However, in recent years phreatomagmatism appears more in association with volcanic eruptions that occur in shallow subaqueous or terrestrial settings and commonly involves molten fuel-coolant interaction (MFCI) driven processes. Here a revised and reviewed classification scheme is suggested on the basis of the geo-environment in which the magma-water interaction takes place and the explosivity plus mode of energy transfer required to generate kinetic energy to produce pyroclasts. Over the past decade researchers have focused on the role hydrovolcanism/phreatomagmatism plays in the formation of maar craters, the evolution of diatremes and the signatures of magma—water interaction in the geological record. In the past five years, lithofacies-characterization is the most common approach to studying hydrovolcanism. By far mafic monogenetic volcanic fields generated the greatest number of research results. Significant knowledge gaps are identified, especially in developing tools to identify the textural signatures hydrovolcanism leave behind on eruptive products and exploring the role of hydrovolcanism in the growth of intermediate and silicic small volume volcanoes.

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