Geochemistry of Hydrothermal Alteration in Volcanic Rocks

Marfil, Silvina Andrea; Maiza, Pedro

doi:10.5772/31517

Cited by 3 publications

(3 citation statements)

References 29 publications

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“…The reference sample is similar for some REEs (lanthanum, cerium, praseodymium, neodymium and samarium) but not for other REEs (gadolinium, terbium, dysprosium, holmium, terbium, thulium, ytterbium, and lutetium). The slight decrease in cerium concentrations at 380 and 440 ft is consistent with redox reactions (Piper and Bau, 2013) and hydrothermal processes within the borehole (Marfil and Maiza, 2012).…”

Section: Geochemical Analysis Of Cuttingssupporting

confidence: 70%

“…The decrease in cerium is consistent with the red, orange, and yellow hydrothermal alteration colors on cuttings and the gray-green or yellow water produced during drilling. Marfil and Maiza (2012) noted that variances in the concentration of cerium and other elements in altered rocks "probably are due to hydrothermal processes." The REE curves for the lower part of the B205 Norris borehole also may reflect problems with drilling through the interval between 210 and 250 ft. For comparison, figure 7 also shows REE geochemistry from an LCT-A outcrop sample (LCT G) collected in Gibbon Canyon (table 2).…”

Section: Geochemical Analysis Of Cuttingsmentioning

confidence: 99%

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Geologic and geochemical results from boreholes drilled in Yellowstone National Park, Wyoming, 2007 and 2008

Jaworowski¹,

Susong²,

Heasler³

et al. 2016

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Section: Geochemical Analysis Of Cuttingssupporting

confidence: 70%

Section: Geochemical Analysis Of Cuttingsmentioning

confidence: 99%

Geologic and geochemical results from boreholes drilled in Yellowstone National Park, Wyoming, 2007 and 2008

Jaworowski¹,

Susong²,

Heasler³

et al. 2016

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“…In continental arcs, the relative contributions to arc magmas, from mantle, crustal and subducted components can be difficult to constrain from whole rock geochemistry alone as it often reflects a complex history of fractional crystallisation and late stage alteration (e.g., McCarthy and Hasty, 1976;Marfil and Maiza, 2012). This is a particular problem in the southern Central Andes where some of the arc magmatic rocks (e.g., the Tilito Formation) have been affected by hydrothermal alteration (Bissig et al, 2001(Bissig et al, , 2003Kay and Mpodozis, 2001;Charchaflié et al, 2007;Litvak et al, 2007).…”

Section: Insights From the Isotopic Composition Of Zirconmentioning

confidence: 98%

Geodynamic controls on the contamination of Cenozoic arc magmas in the southern Central Andes: Insights from the O and Hf isotopic composition of zircon

Jones

Kirstein

Kasemann

et al. 2015

Geochimica et Cosmochimica Acta

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Subduction zones, such as the Andean convergent margin of South America, are sites of active continental growth and crustal recycling. The composition of arc magmas, and therefore new continental crust, reflects variable contributions from mantle, crustal and subducted reservoirs. Temporal (Ma) and spatial (km) variations in these contributions to southern Central Andean arc magmas are investigated in relation to the changing plate geometry and geodynamic setting of the southern Central Andes (28-32°S) during the Cenozoic. The in-situ analysis of O and Hf isotopes in zircon, from both intrusive (granitoids) and extrusive (basaltic andesites to rhyolites) Late Cretaceous -Late Miocene arc magmatic rocks, combined with high resolution U-Pb dating, demonstrates distinct across-arc variations. Mantle-like d 18 O (zircon) values (+5.4& to +5.7& (±0.4 (2r))) and juvenile initial eHf (zircon) values (+8.3 (±0.8 (2r)) to +10.0 (±0.9 (2r))), combined with a lack of zircon inheritance suggests that the Late Cretaceous ($73 Ma) to Eocene ($39 Ma) granitoids emplaced in the Principal Cordillera of Chile formed from mantle-derived melts with very limited interaction with continental crustal material, therefore representing a sustained period of upper crustal growth. Late Eocene ($36 Ma) to Early Miocene ($17 Ma) volcanic arc rocks present in the Frontal Cordillera have 'mantle-like' d 18 O (zircon) values (+4.8& (±0.2 (2r) to +5.8& (±0.5 (2r))), but less radiogenic initial eHf (zircon) values (+1.0 (±1.1 (2r)) to +4.0 (±0.6 (2r))) providing evidence for mixing of mantle-derived melts with the Late Paleozoic -Early Mesozoic basement (up to $20%). The assimilation of both Late Paleozoic -Early Mesozoic Andean crust and a Grenville-aged basement is required to produce the higher than 'mantle-like' d 18 O (zircon) values (+5.5& (±0.6 (2r) to +7.2& (±0.4 (2r))) and unradiogenic, initial eHf (zircon) values (À3.9 (±1.0 (2r)) to +1.6 (±4.4 (2r))), obtained for the Late Oligocene ($23 Ma) to Late Miocene ($9 Ma) magmatic rocks located in the Argentinean Precordillera, and the Late Miocene ($6 Ma) volcanic rocks present in the Frontal Cordillera. The observed isotopic variability demonstrates that the assimilation of pre-existing continental crust, which varies in both age and composition over the Andean Cordillera, plays a dominant role in modifying the isotopic composition of Late Eocene ScienceDirect Geochimica et Cosmochimica Acta 164 (2015) [386][387][388][389][390][391][392][393][394][395][396][397][398][399][400][401][402] to Late Miocene mantle-derived magmas, implying significant crustal recycling. The interaction of arc magmas with distinct basement terranes is controlled by the migration of the magmatic arc due to the changing geodynamic setting, as well as by the tectonic shortening and thickening of the Central Andean crust over the latter part of the Cenozoic.

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Assessment of the alteration and acid-generating potential of deep boreholes for geological disposal

Lee

Chae

et al. 2016

Environ Earth Sci

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Geochemistry of Hydrothermal Alteration in Volcanic Rocks

Cited by 3 publications

References 29 publications

Geologic and geochemical results from boreholes drilled in Yellowstone National Park, Wyoming, 2007 and 2008

Geologic and geochemical results from boreholes drilled in Yellowstone National Park, Wyoming, 2007 and 2008

Geodynamic controls on the contamination of Cenozoic arc magmas in the southern Central Andes: Insights from the O and Hf isotopic composition of zircon

Assessment of the alteration and acid-generating potential of deep boreholes for geological disposal

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