Stable Isotope Geochemistry

Hoefs, Jochen

doi:10.1007/978-3-662-09998-8

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“…The carbon isotope compositions of the studied ophicalcite samples range from -0.1 to 1.7‰ indicating a normal marine origin (e.g. Hoefs 1987), in agreement with other studies on ophicarbonate rocks (Barbieri et al 1979;Lemoine et al 1983;Weissert and Bernoulli 1984;Früh-Green et al 1990;Driesner 36 A. Demény et al Central European Geology 50, 2007 Pozzorini and Früh-Green 1996). This carbon isotope range implies that the calcite may have been precipitated from hydrothermal solutions of seawater origin (containing dissolved carbonate, bicarbonate and CO 2 with a total δ 13 C of about 0‰), or may have been derived from the mechanical mixing of sedimentary carbonate and silicate material and subsequent recrystallization during the metamorphic events.…”

Section: Formation Conditions Of Ophicalcitesupporting

confidence: 89%

“…This carbon isotope range implies that the calcite may have been precipitated from hydrothermal solutions of seawater origin (containing dissolved carbonate, bicarbonate and CO 2 with a total δ 13 C of about 0‰), or may have been derived from the mechanical mixing of sedimentary carbonate and silicate material and subsequent recrystallization during the metamorphic events. Although the δ 18 O values of the matrix calcite (17 to 19.5‰) are significantly more positive than those of the silicate rocks of the studied Penninic unit, they are far lower than normal marine limestone compositions (about 31‰;Hoefs 1987). These values are likely related to higher precipitation temperatures of ophicarbonates relative to marine carbonate precipitation and/or indicate that the fluids were buffered to lower values of δ 18 O by interaction with the silicate hosts.…”

Section: Formation Conditions Of Ophicalcitementioning

confidence: 77%

“…Central European Geology 50, 2007 Suzuoki and Epstein (1976), Graham et al (1984;1987) and Zheng (1993) …”

Section: Stable Isotope Compositions Of the Penninic Ophiolites Of Thmentioning

confidence: 99%

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Stable isotope compositions of the Penninic ophiolites of the Kõszeg-Rechnitz series

Demény¹,

Vennemann²,

Koller³

2007

Central European Geology

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The ophiolitic rocks of the easternmost Penninic unit, the Kõszeg-Rechnitz series, were analyzed for their H, C and O stable isotope compositions. Serpentinite, gabbro, blueschist, talc deposits, ophicarbonates, as well as calcite and inclusion fluids from quartz segregation veins were analyzed in order to determine the effects of different metamorphic events on the stable isotope compositions.The oxygen isotope compositions have a wide range depending on rock type and locality. Gabbro and serpentinite of Bienenhütte (Bernstein Window) have preserved mantle-like δ 18 O values (5.9 to 6.3‰; all values are in ‰ relative to V-SMOW), whereas the serpentinite of Glashütten and Rumpersdorf (Kõszeg-Rechnitz Window) and the silicate minerals of the ophicarbonate rocks show a strong 18 O-enrichment (up to 16.2‰). The 18 O-enrichment may have been induced by lowtemperature serpentinization or interaction with 18 O-rich fluids that had been in equilibrium with sedimentary rocks. Contrary to the O isotope compositions, the H isotope compositions seem to be homogeneous in the entire series, with D values of -63 ± 7‰. Only some serpentinite rocks were depleted in D (down to -106‰), usually regarded as a result of interaction with meteoric water infiltrating during late-stage metamorphism. The meteoric water infiltration was rather limited, as even samples taken directly from slickensides within serpentinite bodies preserved isotopic compositions close to those of the bulk series. H and O isotope compositions of fluids mobilized in the metasedimentary rocks of the Penninic unit during the main metamorphic stage were determined by analyzing inclusion fluids and calcites in quartz-carbonate veins. The isotope compositions indicate interaction between these fluids and the ophiolite series, although relative deuterium enrichment has been preserved in the ophiolitic rocks.The strong D-enrichment characteristic for oceanic crust that has experienced high-temperature interaction with seawater was not detected. However, the H isotope compositions obtained for the Kõszeg-Rechnitz series indicate that subduction of the Penninic oceanic crust and the associated devolatilization may have been potentially responsible for mantle metasomatism, resulting in H Addresses: A. Demény: H-1112 Budapest, Budaörsi út 45, Hungary, e-mail: demeny@geochem.hu T. W. Vennemann: L'Anthropole, CH-1015 Lausanne, Switzerland F. Koller: Althanstr. 14, 1090 Vienna, Austria Received: January 2, , accepted: March 28, 2007 1788-2281/$ 20.00 © 2007 Akadémiai Kiadó, Budapest Central European Geology, Vol. 50/1, pp. 29-46 (2007 DOI: 10.155610. /CEuGeol.50.2007 isotope compositions of about -40‰, similar to the range determined from mantle-derived amphibole megacrysts (Demény et al. 2005). To conclude, the present dataset is discussed in the light of earlier studies on the formation of the Sopron leucophyllite.

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Section: Formation Conditions Of Ophicalcitesupporting

confidence: 89%

Section: Formation Conditions Of Ophicalcitementioning

confidence: 77%

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Stable isotope compositions of the Penninic ophiolites of the Kõszeg-Rechnitz series

Demény¹,

Vennemann²,

Koller³

2007

Central European Geology

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“…(1) -(13) Onuma vd. (1972), Taylor (1974), Hoefs (1987); (14)- (22) Türkiye'deki evaporit yataklarından alınan sülfat minerallerine ait oksijen izotop değerleri (Palmer vd., 2004);(23) Bigadiç bor yataklarından alınan kolemenit minerallerine ait oksijen izotop değerleri; Figure 5. Oxygen-isotopic compositions of the colemanite minerals compared to natural oxygen isotope reservoirs.…”

Section: O Değerinin Tahminiunclassified

Bor Minerallerinin Duraylı İzotop Jeokimyası: Bigadiç (Balıkesir) Borat Yatağından Bir Örnek

Öztürk¹,

Ay²,

Helvacı³

2014

YRB

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ÖZBatı Anadolu'da bulunan Bigadiç borat yatakları Neojen yaşlı playa göl tortullarından yapılı KD-GB uzanımlı bir havza içinde iki farklı zonda yer almaktadır. Bu yataklardan alınan bor minerallerinin jeokimyasal ve duraylı izotop analizleri gerçekleştirilmiştir. Bigadiç Borat yatağından alınan kolemanit örneklerinin oksijen ve hidrojen izotop analizleri ve bu minerallerle ile birarada bulunan kalsit, klorit, montmorillonit gibi minerallere ait sabitler kullanılarak, bor minerallerini oluşturan akışkanın oksijen ve hidrojen izotop değerleri hesaplanmıştır. Bigadiç borat yatağından alınan kolemanit örnek-lerinin oksijen ve hidrojen izotop değerleri sırasıyla, 26.9 -39.9‰ ile -50 --81‰ aralıklarında ölçülmüştür. Bor yataklarının oluşum sıcaklıkları göz önüne alınarak 60, 40 ve 25 0 C tahmini sıcaklıklarda bor mineralleri ile dengedeki akışkanın oksijen ve hidrojen izotop bileşimi hesaplanmıştır. Akışkanın hesaplanan oksijen ve hidrojen izotop değerleri 60 0 C tahmini oluşum sıcaklığında sırasıyla 6.78 -22.51‰ ile -6.66 --23.66‰, 40 0 C tahmini oluşum sı-caklığında sırasıyla 8.72 -30.9‰ ile -13.27 -3.73‰ ve 25 0 C tahmini oluşum sıcaklığında sırasıyla 0.3 -13.3‰ ile -19 -12‰ değer aralıklarında bulunmuştur. Bor mineralleri ve bunlardan hesaplanan dengedeki akışkanın oksijen ve hidrojen izotop değerleri, doğal oksijen ve hidrojen izotop rezervuarları ve Türkiye'de bulunan önemli evaporit yataklarında gözlenen jips ve anhidrit minerallerine ait oksijen izotop değerleri ile karşılaştırılmıştır. Buna göre elde edilen oksijen ve hidrojen izotop değerleri sırasıyla andezit, riyolit ve gölsel evaporitlerin oksijen izotop değerleri ile meteorik su katkılı olduğu düşünülen formasyon sularına ait değerlere yakın olduğu saptanmıştır. Aynı zamanda Bigadiç bor minerallerine ait oksijen izotop değerleri Türkiye'de bulunan önemli evaporit yataklarında gözlenen jips ve anhidrit minerallerine ait oksijen izotop değerleri ile büyük benzerlik sunmaktadır. 26.9 -39.9‰ and -50 --81‰ , respectively.

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“…Diversos estudios isotópicos realizados en zonas asociadas a metamorfismo de contacto y metamorfismo regional en litologías calcáreas han logrado establecer la utilidad del fraccionamiento isotópico de carbono entre grafito y calcita, como geotermó-metro (Wada et al, 1994;Morikiyo, 1986;Hoefs, 1987;Satish-Kumar & Wada, 2000;Baumgartner & Valley, 2001;Deines, 2004). No obstante, en secuencias silicatadas no se conoce bien el comportamiento isotópico a lo largo de la aureola de contacto y su relación con la temperatura de metamorfismo.…”

Section: Introductionunclassified

Correlación entre parámetros químicos, cristalográficos y espectroscópicos en la termometría de grafito aplicada a una aureola de contacto del monzogranito de La Soledad (Andes venezolanos)

Reategui

Martínez

2017

Estud. geol.

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Muestras de grafito provenientes de una aureola de contacto entre filitas de la Asociación Cerro Azul (Paleozoico) y el Monzogranito de La Soledad en Los Andes venezolanos, fueron estudiadas mediante técnicas químicas (% Carbono inorgánico y distribución isotópica), cristalográficas (DRX) y espectroscópicas (Raman) con el fin de evaluar los cambios en las características del grafito en las cercanías del contacto, correlacionar los diferentes parámetros entre sí, y estimar la temperatura máxima alcanzada por la roca caja durante la intrusión ígnea. La cristalografía del grafito exhibe cambios notables, y tiene lugar una disminución en el contenido del mineral en las inmediaciones del contacto. El δ13C alcanzó valores menos negativos en las cercanías al monzogranito, ocasionado por devolatilización; el grafito presente exactamente en el contacto con el plutón pudo experimentar recristalización posterior al evento térmico, con puntual desplazamiento isotópico hacia valores más negativos. El intervalo de valores de grado de grafitización calculados (GD=53–80) corresponde a un mineral bien estructurado y con empaquetamiento ordenado. La temperatura máxima durante el evento intrusivo en el contacto fue calculada a través de los parámetros cristalográficos (DRX) como espectroscópicos (Raman) con gran concordancia en ambas técnicas, registrando 528 ± 16 y 526 ± 20 ºC respectivamente. El nivel metamórfico alcanzado por las rocas metapelíticas en la aureola de contacto comprende la Zona de la Cordierita (cordierita + biotita + muscovita) donde el grafito se halla bien cristalizado y en microtextura hexagonal. Factores como la actividad de fluidos y la recristalización posterior de mineral grafitoso inciden en redistribuciones isotópicas posteriores al evento intrusivo, al igual que en la tasa de cambio de cristalinidad del grafito con la temperatura lo que determina una ausencia clara de correlación entre las variaciones isotópicas de 13C en el grafito y la temperatura.

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Stable Isotope Geochemistry

Abstract: The use ofregistered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

Cited by 436 publications

References 0 publications

Stable isotope compositions of the Penninic ophiolites of the Kõszeg-Rechnitz series

Stable isotope compositions of the Penninic ophiolites of the Kõszeg-Rechnitz series

Bor Minerallerinin Duraylı İzotop Jeokimyası: Bigadiç (Balıkesir) Borat Yatağından Bir Örnek

Correlación entre parámetros químicos, cristalográficos y espectroscópicos en la termometría de grafito aplicada a una aureola de contacto del monzogranito de La Soledad (Andes venezolanos)

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