Elemental fingerprints of isotopic contamination of hebridean Palaeocene mantle-derived magmas by archaean sial

Thompson, R. N.; Dickin, A. P.; Gibson, I. L.; Morrison, M. A.

doi:10.1007/bf01132885

Cited by 173 publications

(74 citation statements)

References 39 publications

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“…Thompson et al, 1982;Campbell and Griffths, 1990;Pearce, 1983). In simple crustal assimilation models, the size of Nb-Ta anomalies and concentrations of elements most affected by contamination (Ba, Rb, K, LREE, Sr; Thompson et al, 1982) are expected to increase with progressively more negative ߳ Nd (T) values. These relationships are not observed among Pikes Peak mafic rocks.…”

Section: Mafic Rocks and Mantle Source Characteristicsmentioning

confidence: 99%

Petrology and geochemistry of late-stage intrusions of the A-type, mid-Proterozoic Pikes Peak batholith (Central Colorado, USA): implications for petrogenetic models

Smith

Noblett

Wobus

et al. 1999

Precambrian Research

164

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. (1999). Petrology and geochemistry of late-stage intrusions of the a-type, mid-Proterozoic pikes peak batholith (central Colorado, USA): Implications for petrogenetic models. Precambrian Research,, 271-305. doi:10.1016/ S0301-9268(99) Gabbros and mafic dikes associated with the sodic granitoids have ߳ Nd (1.08 Ga) of −3.0 to +3.5, which are lower than depleted mantle at 1.08 Ga, and their trace element characteristics suggest derivation from mantle sources that were previously affected by subduction-related processes. However, it is difficult to characterize the mantle component in these magmas, because assimilation of crust during magma ascent could also result in their observed geochemical features.The Pikes Peak batholith is composed of at least two petrogenetically different granite types, both of which exhibit geochemical characteristics typical of A-type granites. Models proposed for the petrogenesis of the granitoids imply the existence of mafic rocks at depth and addition of juvenile material to the crust in central Colorado at ~1.1 Ga.3

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Section: Mafic Rocks and Mantle Source Characteristicsmentioning

confidence: 99%

Petrology and geochemistry of late-stage intrusions of the A-type, mid-Proterozoic Pikes Peak batholith (Central Colorado, USA): implications for petrogenetic models

Smith

Noblett

Wobus

et al. 1999

Precambrian Research

164

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“…4.6). Higher concentrations of rubidium and thorium could possibly be due to crustal contamination but it is unlikely that this is the cause of high heavy-rare-earth concentrations (Thompson et al 1982). The higher concentrations of heavy-rare-earth elements at the same magnesium number of other eruptive units indicate that this is a unique magma.…”

Section: -8mentioning

confidence: 99%

Status of volcanism studies for the Yucca Mountain Site Characterization Project

Crowe¹,

Perry²,

Murrell³

et al. 1995

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; ifs unique idenfzfier assigned to fhis appendix is LA-EES-13-LV-12-95-002. To obtain rgerences bgore fhe appendix is issued, confacf Kean Finnegan at (7021-794-7273 ABSTRACTChapter 1 introduces the volcanism issue for the Yucca Mountain site and provides the reader with an overview of the organization, content, and significant conclusions of this report. The risk of future basaltic volcanism is the primary topic of concern including both events that intersect a potential repository and events that occur near or within the waste isolation system of a repository. Future volcanic events cannot be predicted with certainty but instead are estimated using formal methods of probabilistic volcanic hazard assessment. Chapter 2 describes the volcanic history of the Yucca Mountain region (YMR) and emphasizes the Pliocene and Quaternary volcanic record, the interval of primary concern for volcanic risk assessment. The distribution, eruptive history, and geochronology of Plio-Quaternary basalt centers are described by individual center emphasizing the two cycles of the Postcaldera basalt, the Older postcaldera basalt and the Younger postcaldera basalt. The Lathrop Wells volcanic center is described in detail because it is the youngest basalt center in the YMR, it has been problematic to establish the geochronology of the center; and it probably formed during multiple, timeseparate eruptive events, an unexpected difference from typical monogenetic basaltic volcanic centers. Chapter 3 describes the tectonic setting of the YMR and presents and assesses the significance of multiple alternative tectonic models. The Crater Flat volcanic zone is defined and described as one of many alternative models of the structural controls of the distribution of Plio-Quaternary basalt centers in the YMR. Geophysical data are described for the YMR and are used as an aid to understand the distribution of basaltic volcanic centers. Chapter 4 discusses the petrologic and geochemical features of basaltic volcanism in the YMR, the southern Great Basin and the Basin and Range province. Geochemical and isotopic data are described that indicate basalt of the southern Great Basin was derived from ancient lithospheric mantle. The long time of activity and characteristic small volume of the Postcaldera basalt of the YMR result in one of the lowest eruptive rates in a volcanic field in the southwest United States. Quaternary lavas of the YMR lack plagioclase phenocrysts and fractionated at high pressure in the lower crust or upper mantle before ascent and eruption. The compositional variation of the Lathrop Wells center provides strong evidence of formation from separate and unrelated magma batches. Chapter 5 summarizes current concepts of the segregation, ascent, and eruption of basalt magma. Magma ascending as dikes probably followed northwest-trending structure at depth and diverted at shallow depths following the direction of maximum compressive stress. Chapter 6 summarizes the history of volcanism studies (1979 through early 1994), including work f...

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“…3), which are features of magmatism in an active continental margin setting (Pearce, 1982;Pearce & Peate, 1995;Baier et al, 2008). These geochemical characteristics are, however, not unique to active continental margins and can occur in magmatic rocks from other tectonic settings; for example, magma generated in an anorogenic continental setting can gain arc-like geochemical characteristics through extensive crustal assimilation (Thompson et al, 1982;Pearce et al, 1984;Pearce, 2014). Alternatively, the melting of subcontinental lithospheric mantle (SCLM) with an inherited subduction signature could also generate these geochemical characteristics (e.g.…”

Section: Magmatic Parentage and Tectonic Settingmentioning

confidence: 99%

Geochemistry and origin of Carboniferous (Mississippian; Viséan) bentonites in the Namur-Dinant Basin, Belgium: evidence for a Variscan volcanic source

Pointon¹,

Chew²,

Delcambre³

et al. 2018

Geol. Belg.

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ABSTRACT. Several thin clay-rich horizons occur interbedded with Mississippian (Viséan) limestones in the Namur-Dinant Basin, southern Belgium. These have been interpreted as diagenetically altered volcanic ash layers (bentonites). Whole-rock geochemical analysis of several bentonites was undertaken to provide insight into their original magmatic composition. Ratios of several trace elements that are considered to be immobile during diagenetic alteration and indicators of petrogenetic processes suggest that most of the bentonites were originally trachyandesitic to trachytic ashes. Furthermore, the coarse grain size of euhedral zircon phenocrysts (up to 400 µm in length) suggests a proximal volcanic source. Zircon U-Pb isotopic ages and wholerock geochemical data from these bentonites were compared with literature data from volcanic and intrusive rocks in adjacent areas, and suggest that the bentonites were sourced from volcanoes within the Variscan orogenic belt.KEYWORDS: altered volcanic ash, cinerite, whole-rock geochemistry, trace element geochemistry, X-ray diffraction analysis.http://dx

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Elemental fingerprints of isotopic contamination of hebridean Palaeocene mantle-derived magmas by archaean sial

Cited by 173 publications

References 39 publications

Petrology and geochemistry of late-stage intrusions of the A-type, mid-Proterozoic Pikes Peak batholith (Central Colorado, USA): implications for petrogenetic models

Petrology and geochemistry of late-stage intrusions of the A-type, mid-Proterozoic Pikes Peak batholith (Central Colorado, USA): implications for petrogenetic models

Status of volcanism studies for the Yucca Mountain Site Characterization Project

Geochemistry and origin of Carboniferous (Mississippian; Viséan) bentonites in the Namur-Dinant Basin, Belgium: evidence for a Variscan volcanic source

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