Amphibole composition in tonalite as a function of pressure: an experimental calibration of the Al-in-hornblende barometer

Schmidt, Max W.

doi:10.1007/bf00310745

Cited by 1,237 publications

(798 citation statements)

References 20 publications

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“…6). 각섬석이 형성될 당시의 압력에 대해서 여러 연구 자들 (Hammarstrom and Zen, 1986;Hollister et al, 1987;Schmidt, 1992 (Fig. 10).…”

Section: 서 언unclassified

Petrology of the Syenites in Sancheong, Korea

Ok¹,

Kim²,

Lee³

et al. 2015

The Journal of the Petrological Society of Korea

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Syenite is not a common rock, unlike granitic rocks formed the major component of the continental crust. The aim of this study is to decipher the occurrences and detailed descriptive characteristics of the syenite distributed in Sancheong area, and to investigate the petrogenesis of the syenitic magma based on geochemical study. The dominant minerals in syenite are alkali feldspar (usually orthoclase and rarely microcline), plagioclase, amphibole, biotite, and quartz. Syenites are found in a wide variety of colors. The anhedral hornblende and biotite filling the boundary of feldspar and quartz indicate that the hydrous minerals were crystallized lately, and that water was insufficient at the beginning of crystallization in magma. According to the analysis of mineral composition, amphibole in syenite is mostly ferro-edenite, and the pressure is calculated as 3.3~4.9 kb with 11.9~17.3 km of emplacement depth. Biotite and pyroxene are plotted in the region of annite and hedenbergite, respectively. Based on petrochemical studies of major elements, syenite belongs to alkaline series, metaluminous, and I-type. On the other hand,

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“…6). 각섬석이 형성될 당시의 압력에 대해서 여러 연구 자들 (Hammarstrom and Zen, 1986;Hollister et al, 1987;Schmidt, 1992 (Fig. 10).…”

Section: 서 언unclassified

Petrology of the Syenites in Sancheong, Korea

Ok¹,

Kim²,

Lee³

et al. 2015

The Journal of the Petrological Society of Korea

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“…The change in Al tot with pressure is mainly attributed to a tschermak exchange (Mg -1 Al VI Si -1 Al IV ) and to a minor plagioclase exchange (Ca -1 Na M(4) Al -1 IV Si), whereas the edenite substitution (NaAl IV Si -1 ) is more sensitive to temperature changes (Anderson and Smith 1995;Hammarstrom and Zen 1986;Hollister et al 1987;Johnson and Rutherford 1989;Schmidt 1992).…”

Section: Determination Of Intrusion Pressuresmentioning

confidence: 99%

“…Two experimental calibrations of the Al-in-hornblende barometer have been undertaken: (1) Johnson and Rutherford (1989) employing a mixed CO 2 -H 2 O fluid, thus shifting phase stability fields and the fluid-saturated solidus to temperatures in the range of 740-780°C, and (2) Schmidt (1992) under water-saturated conditions in the temperature range of 655-700°C. Due to the higher temperatures, the former calibration generally yields higher Al tot because of an enhanced edenite substitution (Schmidt 1992).…”

Section: Determination Of Intrusion Pressuresmentioning

confidence: 99%

“…Due to the higher temperatures, the former calibration generally yields higher Al tot because of an enhanced edenite substitution (Schmidt 1992). The Johnson and Rutherford's (1989) calibration was targeted at extrusives where eruption predates final solidification and where hornblende does not equilibrate down to temperatures of the wet solidus.…”

Section: Determination Of Intrusion Pressuresmentioning

confidence: 99%

“…The Johnson and Rutherford's (1989) calibration was targeted at extrusives where eruption predates final solidification and where hornblende does not equilibrate down to temperatures of the wet solidus. For intrusives such as the Kohistan batholith, which have no evidence for CO 2 -bearing fluids or final equilibration much above the wet solidus, the Schmidt's (1992) equation to calculate intrusion pressures: P intrusion (±0.06 GPa) = -3.01 ? 4.76ÁAl tot , calibrated at pressures ranging from 0.25 to 1.3 GPa (Schmidt 1992).…”

Section: Determination Of Intrusion Pressuresmentioning

confidence: 99%

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TTG-type plutonic rocks formed in a modern arc batholith by hydrous fractionation in the lower arc crust

Jagoutz¹,

Schmidt

Enggist

et al. 2013

Contrib Mineral Petrol

Self Cite

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We present the geochemistry and intrusion pressures of granitoids from the Kohistan batholith, which represents, together with the intruded volcanic and sedimentary units, the middle and upper arc crust of the Kohistan paleo-island arc. Based on Al-in-hornblende barometry, the batholith records intrusion pressures from *0.2 GPa in the north (where the volcano-sedimentary cover is intruded) to max. *0.9 GPa in the southeast. The Al-in-hornblende barometry demonstrates that the Kohistan batholith represents a complete cross section across an arc batholith, reaching from the top at *8-9 km depth (north) to its bottom at 25-35 km (south-central to southeast). Despite the complete outcropping and accessibility of the entire batholith, there is no observable compositional stratification across the batholith. The geochemical characteristics of the granitoids define three groups. Group

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Eocene adakitic porphyries in the central‐northern Qiangtang Block, central Tibet: Partial melting of thickened lower crust and implications for initial surface uplifting of the plateau

Wang

Wyman

et al. 2017

JGR Solid Earth

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The time and mechanism of crustal thickening and initial surface uplift of the Tibetan Plateau remain highly controversial. Here we report on zircon U‐Pb age, and mineral, element, and Sr‐Nd isotope composition data for Eocene adakitic porphyries in the Laorite Co area of central‐northern Qiangtang Block, central Tibet. Laser ablation‐inductively coupled plasma‐mass spectrometry zircon U‐Pb age dating shows that the porphyries were generated at 42–41 Ma. All samples display adakitic geochemical characteristics, such as high SiO2 and Al2O3, and low Y and Yb contents, and high Sr/Y and La/Yb ratios with positive Sr and negligible Eu anomalies and Nb‐Ta depletion. They also have low magnesium number (Mg #) (16–45) and high K2O (4.0–4.6 wt %) values, as well as high (87Sr/86Sr)i (0.7076–0.7080) and low εNd(t) (−5.9 to −4.4) values. These adakitic rocks were most probably generated by partial melting of thickened lower crust in the stability field of garnet, amphibole, and rutile but with relatively minor plagioclase. Moreover, such a crustal thickening process beneath this block likely occurred no later than the middle Eocene and was most probably caused by the southward subduction of the Songpan‐Ganzi Block in the early Cenozoic. In addition, the occurrences of exposed adakitic porphyries unambiguously indicate that exhumation process occurred after their formation. Thus, these ~42 Ma adakitic porphyries indicate the occurrence of significant exhumation since 42 Ma. Integrated with the thermochronological and paleoelevation data, we suggest that the initial surface uplift of the Qiangtang Block, triggered by crustal thickening, was underway by the middle Eocene (~42 Ma).

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Amphibole composition in tonalite as a function of pressure: an experimental calibration of the Al-in-hornblende barometer

Cited by 1,237 publications

References 20 publications

Petrology of the Syenites in Sancheong, Korea

Petrology of the Syenites in Sancheong, Korea

TTG-type plutonic rocks formed in a modern arc batholith by hydrous fractionation in the lower arc crust

Eocene adakitic porphyries in the central‐northern Qiangtang Block, central Tibet: Partial melting of thickened lower crust and implications for initial surface uplifting of the plateau

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