scholarly journals Lead isotopes of granitic rocks from the Hida metamorphic belt and some isotopic features of igneous rocks in Japan

1973 ◽  
Vol 7 (4) ◽  
pp. 231-244 ◽  
Author(s):  
Akira Miyazaki ◽  
Kazuo Sato ◽  
Nobufusa Saito
Keyword(s):  
Lead Isotopes ◽  
Igneous Rocks ◽  
Granitic Rocks ◽  
Metamorphic Belt

The distribution of gold and silver in the crystalline rocks of the Malvern Hills

1936 ◽  
Vol 24 (152) ◽  
pp. 260-264 ◽  
Author(s):  
A. Brammall ◽  
D. L. Dowie
Keyword(s):  
Spectroscopic Data ◽  
Senior Author ◽  
Crystalline Rocks ◽  
Igneous Rocks ◽  
Granitic Rocks ◽  
Image Position

In re-examining the crystalline rocks of the Malvern Hills, the senior author has had occasion to apply quantitative spectroscopic data for the rarer constituents of hornblendes and micas. The recognition of silver in the spectrograms of biotite led to tentative fire-assays of granitic rocks in bulk-a procedure which revealed the presence also of gold.The assay results for this preliminary suite of granitic types are given below; values less than 5 grains per ton are returned as 'traces':The higher values appear to be related to the reddening of the felspars, which is a widespread 'late' pneumatolytic effect; it is conspicuous in the major granite masses and related pegmatites, but somewhat local and 'arterial' in its distribution over rocks of pre granite age. Among the igneous rocks of post-granite age, the intrusive granophyric quartz-diabase ('Ivy Scar' type) shows only feeble reddening; the newer dolerites are unaffected.

Rb–Sr Geochronology of the Hida metamorphic belt, Japan

1970 ◽  
Vol 7 (6) ◽  
pp. 1383-1401 ◽  
Author(s):  
K. Shibata ◽  
T. Nozawa ◽  
R. K. Wanless
Keyword(s):  
Granitic Rocks ◽  
Metamorphic Event ◽  
Crystalline Schist ◽  
Metamorphic Rocks ◽  
Schist Belt ◽  
Metamorphic Belt ◽  
Early Mesozoic ◽  
Mineral Isochron ◽  
Middle Paleozoic ◽  
Later Phase

Rb–Sr whole-rock and mineral isochron ages have been determined for metamorphic and granitic rocks of the Hida metamorphic belt. The results indicate that an extensive metamorphic event together with plutonic activity took place within the belt during the latest Paleozoic – early Mesozoic period. The older ages of 220–250 m.y. represent an earlier phase of the metamorphism, whereas the younger ages of 170–180 m.y. represent a later phase. The Funatsu granitic rocks yielded a whole-rock isochron age of 176 m.y. with an initial 87Sr/86Sr ratio of 0.7056. This age is believed to indicate the time of original emplacement, and the rocks are considered to represent late-kinematic intrusion in the Hida belt.Some information on the middle Paleozoic metamorphism in the Hida Mountains was obtained from the isochron study. The whole-rock isochron age of 412 m.y. for the metamorphic rocks of the Fujibashi area may be considered, although not confirmed, to indicate the time of older metamorphism. The Omi Schist of the Circum–Hida crystalline schist belt, which belongs to the glaucophanitic type of metamorphism, gave a mineral isochron age of 350 m.y. thereby providing evidence of mid-Paleozoic metamorphism.The initial 87Sr/88Sr ratios for the whole-rock samples of the Hida metamorphic belt are found to be generally low, i.e. 0.705–0.708. This is especially so for the metamorphic rocks from the northern part of the belt where the lowest values were found.

Variety and genesis of the pyroxene-bearing S- and I-type granitoids from the Hidaka Metamorphic Belt, Hokkaido, northern Japan

2004 ◽  
Vol 95 (1-2) ◽  
pp. 161-179 ◽  
Author(s):  
Toshiaki Shimura ◽  
Masaaki Owada ◽  
Yasuhito Osanai ◽  
Masayuki Komatsu ◽  
Hiroo Kagami
Keyword(s):  
Partial Melting ◽  
Granulite Facies ◽  
Mafic Granulite ◽  
Granitic Rocks ◽  
Metamorphic Rocks ◽  
Metamorphic Belt ◽  
Model Calculations ◽  
Magmatic Arc ◽  
River Region ◽  
Northern Japan

ABSTRACTThe high-dT/dP-type Hidaka Metamorphic Belt in Hokkaido, northern Japan, represents a tilted crustal section of a magmatic arc of Tertiary age. The highest metamorphic grades reached are granulite facies, and the syn-metamorphic granitic rocks are widely distributed in this metamorphic terrane. The granitic rocks are mainly tonalitic and granodioritic in composition, and are classified into peraluminous (S-type) and metaluminous (I-type) granitoids. A large amount of pyroxene-bearing S-type tonalites (garnet-orthopyroxene tonalite) is distributed in the Niikappu river region in the northern part of the Hidaka Metamorphic Belt. Pyroxene-bearing I-type tonalite (two-pyroxene hornblende tonalite) bodies are also distributed in this area.The pyroxene-bearing tonalites are classified into several sub-types on the basis of their field occurrence, texture, mineral assemblage and geochemical features. Homogeneous IH- and SH-type tonalite are thought to represent original magmas, i.e. those which have been generated by partial melting of mafic metamorphic rocks and pelitic-psammitic metamorphic rocks, respectively. Model calculations assuming batch partial melting indicate that possible restites are garnet-two-pyroxene mafic granulite for IH-type and garnet-orthopyroxene aluminous granulite for SH-type. The unexposed lowermost crust of the ‘Hidaka crust’ is thought to be composed of garnet-two-pyroxene mafic granulite, garnet-orthopyroxene aluminous granulite and metagabbros.

Melting of subducted continental crust during collision and exhumation: Insights from granitic rocks from the North Qaidam UHP metamorphic belt, NW China

Lithos ◽  
2020 ◽  
Vol 378-379 ◽  
pp. 105794
Author(s):  
Shixiang Yang ◽  
Li Su ◽  
Shuguang Song ◽  
Mark B. Allen ◽  
Di Feng ◽  
...  
Keyword(s):  
Continental Crust ◽  
Granitic Rocks ◽  
Metamorphic Belt ◽  
Nw China ◽  
The North ◽  
North Qaidam

scholarly journals The ammonium content in the Malayer igneous and metamorphic rocks (Sanandaj-Sirjan Zone, Western Iran)

2011 ◽  
Vol 62 (2) ◽  
pp. 171-180 ◽  
Author(s):  
Vahid Ahadnejad ◽  
Ann Hirt ◽  
Mohammad-Vali Valizadeh ◽  
Saeed Bokani
Keyword(s):  
Colorimetric Method ◽  
Igneous Rocks ◽  
Granitic Rocks ◽  
Metamorphic Rocks ◽  
Low Grade ◽  
High Concentration ◽  
Western Iran ◽  
Metasedimentary Rocks ◽  
Sanandaj Sirjan Zone ◽  
External Sources

The ammonium content in the Malayer igneous and metamorphic rocks (Sanandaj-Sirjan Zone, Western Iran)The ammonium (NH4+) contents of the Malayer area (Western Iran) have been determined by using the colorimetric method on 26 samples from igneous and metamorphic rocks. This is the first analysis of the ammonium contents of Iranian metamorphic and igneous rocks. The average ammonium content of metamorphic rocks decreases from low-grade to high-grade metamorphic rocks (in ppm): slate 580, phyllite 515, andalusite schist 242. In the case of igneous rocks, it decreases from felsic to mafic igneous types (in ppm): granites 39, monzonite 20, diorite 17, gabbro 10. Altered granitic rocks show enrichment in NH4+(mean 61 ppm). The high concentration of ammonium in Malayer granites may indicate metasedimentary rocks as protoliths rather than meta-igneous rocks. These granitic rocks (S-types) have high K-bearing rock-forming minerals such as biotite, muscovite and K-feldspar which their potassium could substitute with ammonium. In addition, the high ammonium content of metasediments is probably due to inheritance of nitrogen from organic matter in the original sediments. The hydrothermally altered samples of granitic rocks show highly enrichment of ammonium suggesting external sources which intruded additional content by either interaction with metasedimentary country rocks or meteoritic solutions.

The origin of a Pre-Cambrian diorite-granite plutonic series from Pembrokeshire (Wales)

1970 ◽  
Vol 107 (6) ◽  
pp. 491-499 ◽  
Author(s):  
R. S. Thorpe
Keyword(s):  
Parent Magma ◽  
Igneous Rocks ◽  
Granitic Rocks ◽  
Chemical Analyses ◽  
Magmatic Differentiation ◽  
Similar Composition

SummaryA series of dioritic, granodioritic and granitic igneous rocks, of Pre-Cambrian age, is exposed near Johnston in south Pembrokeshire. Chemical analyses of representative rocks show the suite to be of calcalkaline type. An origin is suggested involving magmatic differentiation of a diorite parent magma, and the granitic rocks are compared with a granophyre of similar composition in north Pembrokeshire.

scholarly journals Petrology and mineral chemistry of peraluminous Marziyan granites, Sanandaj-Sirjan metamorphic belt (NW Iran)

2015 ◽  
Vol 66 (5) ◽  
pp. 361-374 ◽  
Author(s):  
Esmaiel Darvishi ◽  
Mahmoud Khalili ◽  
Roy Beavers ◽  
Mohammad Sayari
Keyword(s):  
Mineral Chemistry ◽  
White Mica ◽  
Granitic Rocks ◽  
Calc Alkaline ◽  
Metamorphic Belt ◽  
Nw Iran ◽  
The North ◽  
Continental Plate ◽  
High K ◽  
Type Granite

AbstractThe Marziyan granites are located in the north of Azna and crop out in the Sanandaj-Sirjan metamorphic belt. These rocks contain minerals such as quartz, K-feldspars, plagioclase, biotite, muscovite, garnet, tourmaline and minor sillimanite. The mineral chemistry of biotite indicates Fe-rich (siderophyllite), low TiO2, high Al2O3, and low MgO nature, suggesting considerable Al concentration in the source magma. These biotites crystallized from peraluminous S-type granite magma belonging to the ilmenite series. The white mica is rich in alumina and has muscovite composition. The peraluminous nature of these rocks is manifested by their remarkably high SiO2, Al2O3and high molar A/CNK (> 1.1) ratio. The latter feature is reflected by the presence of garnet and muscovite. All field observations, petrography, mineral chemistry and petrology evidence indicate a peraluminous, S-type nature of the Marziyan granitic rocks that formed by partial melting of metapelite rocks in the mid to upper crust possibly under vapour-absent conditions. These rocks display geochemical characteristics that span the medium to high-K and calc-alkaline nature and profound chemical features typical of syn-collisional magmatism during collision of the Afro-Arabian continental plate and the Central Iranian microplate.

III.—On the Classification and Nomenclature of Rocks

1875 ◽  
Vol 2 (12) ◽  
pp. 583-587
Author(s):  
S. Allport
Keyword(s):  
Igneous Rocks ◽  
The Other ◽  
Granitic Rocks ◽  
Acidic Group

In the September Number of the Geol. Mag. pp. 425, 426, there are some remarks by Mr. G. H. Kinahan on the nomenclature of certain igneous rocks, on which I should like to offer a few observations. The rocks referred to belong to the acidic group, and are mentioned under the various names of granite, nevadite, granitic rhyolite, liparite, trachyte, elvanite, siliceous elvanite, felstone, bottleite, trachalite; the two last being synonymous, for it appears that bottleite is the local name for a vitrioid rock pronounced to be trachalite; but several of the other names are also synonymous or useless, for we are told that nevadite—a proposed new addition to our granitic rocks—is characterized by a more or less crystalline felsitic matrix inclosing crystals of quartz, one or two felspars with mica or amphibole.

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