Petrogenesis of Metamorphic Rocks

Winkler, Helmut G. F.

doi:10.1007/978-1-4612-9828-1

Cited by 219 publications

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“…Clay minerals (hydroxy-interlayered vermiculite and kaolinite) constitute 40% of the total clay fraction, and pyrophyllite is absent in the C horizon. The parent rock of profile 3 (yellowish sandstone) was probably subjected to high grade diagenesis rather than metamorphism, as a result of which clay minerals were conserved (Winkler, 1974). This is confirmed by the absence of pyrophyllite, associated with low-grade metamorphism, in the C material.…”

Section: Particle Size Distribution and Mineralogical Composition Of mentioning

confidence: 81%

“…The difference between the various rock types is small, being a larger K-mica and pyrophyllite content and a smaller quartz content in the phyllites (Table 2). Such a mineralogical composition is characteristic for pellitic sediments, consisting of clay minerals, which were subjected to low-grade metamorphism (Turner, 1968;Winkler, 1974). The typical K-mica of low-grade metamorphism is a muscovite of so called phengitic composition, which means that the Si/A1 ratio in the tetrahedra is large, caused by substitution of octahedral Al by Fe and Mg and the occurrence of some chloritic inter layering (Weaver and Beck, 1971;Verstraten, 1980).…”

Section: Mineralogy Of the Parent Rocksmentioning

confidence: 99%

“…The soils in this hilly area are best developed on the broad crests, while erosion dominates on steep upper slopes and colluvial soils occur on the foot slopes (Pedroli et al, 1988). The soil profiles on these crests provided an excellent opportunity to study soil formation under mediter-ranean climatic conditions, whence the mineral composition of the acid, low-grade metamorphic parent rock varies within a narrow, well-known range (Turner, 1968;Weaver and Beck, 1971;Winkler, 1974).…”

Section: Introductionmentioning

confidence: 99%

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Pedogenesis by clay dissolution on acid, low-grade metamorphic rocks under mediterranean forests in southern Tuscany (Italy)

Wesemael

Verstraten

Sevink

1995

CATENA

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Pedogenesis by clay dissolution on acid, low-grade metamorphic rocks under mediterranean forests in southern Tuscany (Italy) van Wesemael, B.; Verstraten, J.M.; Sevink, J. Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. AbstractPedogenesis on acid, low-grade metamorphic rocks under well-developed forests was studied in the meso-mediterranean climatic zone. To that purpose three representative soil profiles on phyllite and sandstone under sclerophyllous oak, pine and heathland were selected. The major soil forming processes consisted of transformation of part of the K-mica (muscovite) to (hydroxy-interlayered) vermiculite and smectite, impoverishment both in major elements (A1, K, Mg and Fe) and fine particles, and redistribution of sesquioxides as organic complexes. These processes indicate clay hydrolysis under acid conditions and subsequent removal of solutes by lateral subsurface flow. The resulting impoverishment of the soil profiles could be mainly attributed to hydrolysis under acid conditions brought about by slow decomposition of organic matter. The proposed mode of pedogenesis deviates strongly from the current concept of fersiallitisation, and is probably restricted to acid parent materials in mediterranean climates where lateral removal of soluble weathering products is ensured throughout the largest part of the year.

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Section: Particle Size Distribution and Mineralogical Composition Of mentioning

confidence: 81%

Section: Mineralogy Of the Parent Rocksmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Pedogenesis by clay dissolution on acid, low-grade metamorphic rocks under mediterranean forests in southern Tuscany (Italy)

Wesemael

Verstraten

Sevink

1995

CATENA

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“…4). This assemblage is not stable at a pressure lower than 300 MPa and indicates A temperature of ~570 °C at ~300 MPa has been proposed for the equilibrium conditions of such a reaction (Thompson & Norton 1968;Carmichael 1970;Winkler 1974). Field observations confirm that such retrograde conditions occurred simultaneously with the intrusion of younger aplitic-pegmatitic dykes into the high-grade schists/migmatites (Fig.…”

Section: Mineral Chemistrymentioning

confidence: 87%

Low pressure migmatites from the Sanandaj-Sirjan Metamorphic Belt in the Hamedan region (Iran)

Sepahi¹,

Jafari²,

Mani-Kashani³

2009

Geologica Carpathica

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Migmatites with evidence for low pressure metamorphism and partial melting occur adjacent to the Alvand Plutonic Complex in the Hamedan region of Iran. They show stromatic, schollen, diktyonitic and massive structure. Sillimanite/andalusite/(kyanite)-garnet-and cordierite-K-feldspar-andalusite-spinel-bearing migmatites are the most common rock types. Some of the granitic intrusions contain xenocrysts which resemble the porphyroblasts of nearby migmatites (e.g. sillimanite, andalusite, cordierite and garnet). Although migmatitic rocks of the region are located near the granitic intrusions, the degree of partial melting is not related to intrusions and is irregular. It appears that partial melting and migmatization pre-date the intrusion of major granitic bodies in the region. Leucosomes in stromatic migmatites are commonly parallel to bedding planes and are mostly formed by metamorphic segregation and/or in situ partial melting (showing mafic selvedges, pinch and swell structures). The melt fraction and migmatite type depend on the chemical composition of parent rocks and the distribution of high strain zones. The formation of thin leucosomes in the stromatic migmatites was controlled by short-range melt movement along the grain boundaries. Melt-rich layers are constrained by pre-existing compositional layering and foliation. Peak metamorphic conditions of ~650 °C and ~300 MPa are consistent with the observed mineral assemblages and the presence of melt in the investigated migmatites.Key words: Iran, Sanandaj-Sirjan, Hamedan, anatexis, granite, migmatite.new data pertaining to the petrogenesis of migmatites (especially of stromatic migmatites) near to the Alvand Plutonic Complex in the Hamedan region. Geological settingThe study area is a part of the so-called Sanandaj-Sirjan Zone or Zagros Imbricate Zone of the Zagros Orogen (according to Alavi 1994Alavi , 2004. This zone comprises a metamorphic belt of low-to high-grade regional and contact metamorphic rocks that have been intruded by mafic, intermediate and felsic plutonic bodies (Fig. 1). Major metamorphic and magmatic events of the Sanandaj-Sirjan Metamorphic Belt (SSMB) occurred during the Mesozoic Era (e.g. Baharifar 1997Baharifar , 2004Sepahi 1999;Rashidnejad-Omran et al. 2002;Sheikholeslami et al. 2003;Sepahi et al. 2004;Ahmadi-Khalaji et al. 2007). Major granitic plutons of the SSMB have been atributed to the Mesozoic-Tertiary magmatism (~200 to ~40 Ma; e.g. Valizadeh & Cantagrel 1975;Masoudi 1997;Baharifar 2004;Ahmadi-Khalaji et al. 2007;Arvin et al. 2007). These events have been related to the subduction of the Neo-Tethys and later collisional events (e.g. Baharifar 1997Baharifar , 2004Sepahi 1999 andSepahi et al. 2004). Field relations and petrography of the major plutonic and metamorphic rocksIn the Hamedan region, low-to high-grade, regional and contact metamorphic rocks occur adjacent to plutonic bodies (Fig. 2). Metapelitic rocks are the most abundant, compris-

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“…AMPHIBOLITE ASSEMBLAGE High-temperature deuteric alteration is represented in the gabbroic rocks by the formation of cummingtonite/ anthophyllite (optical and microprobe determinations) from orthopyroxene; the coexisting altered orthopyroxene, calcic plagioclase, diopside, and local hornblende represent the labradorite/bytownite amphibolite facies of Winkler (1974). The cummingtonite/anthophyllite appears to be more Mg rich than the coexisting orthopyroxene (table 2) and typically is accompanied by minor amounts of magnetite.…”

Section: Alteration and Veining Of Gabbroic Rocksmentioning

confidence: 99%

Geology of part of the Nelchina River Gabbronorite and associated rocks, south-central Alaska

Burns¹

1995

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Petrogenesis of Metamorphic Rocks

Cited by 219 publications

References 0 publications

Pedogenesis by clay dissolution on acid, low-grade metamorphic rocks under mediterranean forests in southern Tuscany (Italy)

Pedogenesis by clay dissolution on acid, low-grade metamorphic rocks under mediterranean forests in southern Tuscany (Italy)

Low pressure migmatites from the Sanandaj-Sirjan Metamorphic Belt in the Hamedan region (Iran)

Geology of part of the Nelchina River Gabbronorite and associated rocks, south-central Alaska

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