Elastic properties of amphibolite and granulite facies mid-crustal basement rocks of the Deccan volcanic covered 1993 Latur-Killari earthquake region, Maharastra (India) and mantle metasomatism

2012 ◽  
Vol 554-557 ◽  
pp. 159-168 ◽  
Author(s):  
Priyanka Tripathi ◽  
O.P. Pandey ◽  
M.V.M.S. Rao ◽  
G. Koti Reddy
Keyword(s):  
Elastic Properties ◽  
Granulite Facies ◽  
Mantle Metasomatism ◽  
Basement Rocks

Petrology and geochronology of cordierite bearing assemblages from the Wanni Complex – Sri Lanka

2020 ◽  
Author(s):  
Nikolaus Lechner ◽  
Christoph Hauzenberger ◽  
Marcel Masten ◽  
Dominik Sorger ◽  
G.W.A. Rohan Fernando
Keyword(s):  
Sri Lanka ◽  
Rock Type ◽  
Granulite Facies ◽  
Granulite Facies Metamorphism ◽  
Pan African ◽  
Basement Rocks ◽  
The Matrix ◽  
The Common ◽  
Group 2 ◽  
Uht Metamorphism

<p>Based on differences in metamorphic grade and isotope model ages, the basement rocks of Sri Lanka can be subdivided from NW to SE into the Wanni Complex (WC), the Highland Complex (HC) and the Vijayan Complex (VC) (Milisenda et al. 1994). The UHT conditions of the HC were studied extensively and are well constrained whereas data from the WC and VC are less abundant. Only few recent petrological and geochemical work has been done especially along the WC–HC boundary which is still ill-defined (Kitano et al. 2018; Wanniarachchi & Akasaka 2016). Due to the common occurrence of migmatites, pyroxene bearing gneisses, and cordierite bearing metapelites/paragneisses, the WC clearly experienced granulite facies metamorphism. However, PT conditions are lower compared to the HC. In this study, U-Th-Pb monazite dating combined with a petrological study including phase equilibria modelling and thermobarometry was conducted focusing on cordierite bearing migmatic biotite gneisses located at the WC–HC boundary in the West of Sri Lanka. The HC underwent UHT metamorphism at 580-570Ma (Sajeev et al. 2010), the main metamorphic phase of the VC is dated with 580Ma. (Kröner et al., 2013). With U-Th-Pb monazite ages of around 530 Ma, the cordierite bearing assemblages from the WC are significantly younger (Wanniarachchi & Akasaka 2016). The predominantly felsic but also mafic peraluminous migmatic ortho- and paragneisses comprising the mineral assemblage cordierite + garnet + biotite + plagioclase + k-feldspar + quartz + ilmenite + magnetite + spinel + sillimanite ± orthopyroxene and contain monazite (+ zircon ± xenotime) as garnet inclusions (Group1) and in the matrix (Group2). Group1 monazite ages cluster around 575±5 Ma and 561±5 Ma whereas ages of Group 2 cluster at 550±3 and 527±3. Based on ages and textural occurrence of monazite we suggest that two thermal events at ca. 550-575 Ma and ca. 530-550 Ma are recorded in this rock type indicating a complex evolution during the late stage of the Pan-African orogeny. PT conditions range from 700–900°C and from 5–8 kbar with a decreasing north-south gradient. Further geochronological investigations are needed to relate either to the older or the younger overprint to the main metamorphic phase of the WC.</p><p>Kitano, I., Osanai, Y., Nakano, N., Adachi, T., & Fitzsimons, I. C. W. (2018). Journal of Asian Earth Sciences, 156, 122–144.</p><p>Kröner, A., Rojas-Agramonte, Y., Kehelpannala, K. V. W., Zack, T., Hegner, E., Geng, H. Y., … Barth, M. (2013). Precambrian Research, 234, 288–321. </p><p>Milisenda, C. C., Liewa, T. C., Hofmanna, A. W., & Köhler, H. (1994). Precambrian Research, 66(1–4), 95–110.</p><p>Sajeev, K., Williams, I. S., & Osanai, Y. (2010). Geology, 38(11), 971–974.</p><p>Wanniarachchi, D. N. S., & Akasaka, M. (2016). Journal of Mineralogical and Petrological Sciences, 111(5), 351–362.</p>

scholarly journals P- T PATH RECONSTRUCTION IN NEOPROTEROZOIC GARNET-BEARING PARAGNEISSES FROM A METASEDIMENTARY SUCCESSION OF THE SOUTH WESTERN ARAÇUAÍ OROGEN, MINAS GERAIS, BRAZIL

2015 ◽  
Author(s):  
Reik Degler ◽  
Tiago Amâncio Novo ◽  
Bernhard Schulz ◽  
Gláucia Nascimento Queiroga
Keyword(s):  
Granulite Facies ◽  
Minas Gerais ◽  
Maximum Temperature ◽  
Maximum Pressure ◽  
The South ◽  
Garnet Porphyroblasts ◽  
Magmatic Arc ◽  
Basement Rocks ◽  
T Path ◽  
Araçuaí Orogen

Abstract: This paper focuses on pressure- and temperature path analyses in paragneisses from a metasedimentary succession (MSS) in the south western Araçuaí orogen. The sampling area is limited by the Abre Campo shear zone (West) and the Rio Doce Magmatic Arc (East). This region is rich in ortho-derived metamorphic basement rocks (Mantiqueira and the Juiz de Fora complexes) and para-derived metamorphic rocks, including paragneisses interlaid by quartzites, which form the MSS. The sampled rocks are mainly compost of quartz, plagioclase, garnet, K-Feldspar, orthopyroxene and sillimanite. Measurement spot profiles through garnet porphyroblasts show a certain zonation characterised by decrease in pyrope and the increase in almandine from the core to the rim. This implies retrograde growth. Metamorphic conditions are of high amphibolite- to granulite facies with maximum pressure of ca. 6 kbar and maximum temperature of ca. 700°C. The data suggest that the cores of the garnet porphyroblasts of MSS started to grow during the final deformation stage of the Araçuaí orogen (south western part); the event of decompression is captured in the rims of the porphyroblasts and related to the gravitational collapse in the Cambrian. Keywords: P-T path, metasedimentary succession, geothermobarometry, Araçuaí orogenResumo: RECONSTRUÇÃO DE TRAJETÓRIAS P-T EM PARAGNAISSES GRANADÍFEROS NEOPROTEROZÓICOS DA UMA SUCESSÃO METASSEDIMENTAR NO SUDOESTE DO ORÓGENO ARAÇUAÍ, MINAS GERAIS, BRASIL. Este estudo foca analises de caminhos de pressão e temperatura em paragnaisses de sucessão metassedimentar (SMS) da região sudoeste do Orógeno Araçuaí. A área de amostragem é limitada pela zona de cisalhamento de Abre Campo a oeste e pelo Arco Magmático Rio Doce a leste. A região é rica em rochas metamórficas de alto grau ortoderivadas (complexos Mantiqueira e Juiz de Fora do embasamento) e paraderivadas; incluindo paragnaisses intercalados a quartzitos, que formam o SMS. As rochas amostradas são compostas por quartzo, plagioclásio, granada, feldspato potássio, ortopiroxênio e sillimanita. Perfis de pontos de análise em porfiroblastos de granada mostram certo zoneamento caracterizado pela redução de piropo e por aumento de almadina do núcleo para borda; isto implica em crescimento de cristal sob condições de metamorfismo retrógrado. Condições metamórficas são de fácies anfibolito alto a granulito com um máximo de pressão de ca. 6 kbar e com temperatura máxima de ca. 700°C. Os dados sugerem que porfiroblastos de granada da SMS têm nucleação e início de crescimento durante o final da etapa deformacional principal compressiva do Orógeno Araçuaí (região sudoeste do orógeno); o evento de descompressão captado em bordas dos porfiroblastos foi relacionando ao colapso gravitacional no Cambriano. Palavras-chave: Trajetórias P-T, sucessão metassedimentar, geotermobarometria, Orógeno Araçuaí

scholarly journals Field work between Fiskefjord and Godthåbsfjord, southern West Greenland

1984 ◽  
Vol 120 ◽  
pp. 45-50
Author(s):  
A.A Garde
Keyword(s):  
Granulite Facies ◽  
Field Work ◽  
Precambrian Basement ◽  
The South ◽  
West Greenland ◽  
Basement Rocks ◽  
Logistic Support

The 1980-1981 field work in Precambrian basement rocks for the Fiskefjord map sheet was continued in 1983. V. R. McGregor mapped granulite facies gneisses south of outer Fiskefjord in the south-western part of the map sheet area. The author worked inland between Godthåbsfjord and Fiskefjord from the eastern map sheet boundary at 50°54'E westwards to 51°45'E (fig. 22) and some notes concerning the lithologies, geometry and geochronology of this area are presented below. The GGU cutter K. J. V. Steenstrup and a Jet Ranger helicopter on weekly charter from Godthåb provided logistic support for the two Fiskefjord teams and for four teams mapping in the Ivisårtoq area (see Brewer et al., this report) as well as for the GGU glaciological station at Qamanârssûp serrnia.

The chemical evolution from older (323–318 Ma) towards younger highly evolved tin granites (315–314 Ma)—sources and metal enrichment in Variscan granites of the Western Erzgebirge (Central European Variscides, Germany)

2020 ◽  
Author(s):  
Marion Tichomirowa ◽  
Axel Gerdes ◽  
Manuel Lapp ◽  
Dietmar Leonhardt ◽  
Martin Whitehouse
Keyword(s):  
Granulite Facies ◽  
Source Rocks ◽  
Metamorphic Rocks ◽  
Control Factor ◽  
Basement Rocks ◽  
Ore Bodies ◽  
O Isotopes ◽  
Variscan Granites ◽  
Highly Evolved

<p>The sources and critical enrichment processes for granite related tin ores are still not well understood. The Erzgebirge represents one of the classical regions for tin mineralization. We investigated the four largest plutons from the Western Erzgebirge (Germany) for the geochemistry of bulk rocks and autocrystic zircons and relate this information to their intrusion ages. The source rocks of the Variscan granites were identified as high-grade metamorphic rocks based on the comparison of Hf-O isotope data on zircons, the abundance of xenocrystic zircon ages as well as Nd and Hf model ages. Among these rocks, restite is the most likely candidate for later Variscan melts.</p><p>In contrast to previously published suggestions (Romer and Kroner, 2015; Wolf et al., 2018), we can exclude a substantial role of intense sedimentary weathering as an important control factor for later Sn and W enrichment in granite related ores of the Western Erzgebirge due to the remarkable homogeneous Hf and low O isotopes in granitic zircons that are extremely distinct to all pre-Devonian basement rocks of Saxothuringia. We document a source enrichment from meta-sedimentary rocks (575 Ma) towards metamorphic rocks (340 Ma) were restites from granulite-facies melts are enriched 6–7 times in Sn compared to UCC (upper continental crust). These rocks are also enriched in K, but depleted in Na and Ca, contain abundant muscovite, and are fertile for later melting. Further enrichment of Sn and W occurred during multiple melt production of the older igneous granites (323–318 Ma) leading finally to a general enrichment of Sn (15 times compared to UCC) in the tin granites (315-314 Ma). Multiple melt production did not lead to a very strong enrichment of ore metals in the granites but is probably very important for a general enrichment of Sn and W in the thick granite-rich crust of the Erzgebirge. Efficient leaching by hydrothermal fluids led to a very strong enrichment (up to several orders) of Sn and W in the greisen ore bodies.</p><p> </p><p>References:</p><p>Romer, R.L.; Kroner, U. Sediment and weathering control on the distribution of Paleozoic magmatic tin-tungsten mineralization. Mineral. Depos. 2015, 50, 327–338, doi:10.1007/s00126-014-0540-5.</p><p>Wolf, M.; Romer, R.L.; Franz, L.; Lopez-Moro, F.J. Tin in granitic melts: The role of melting temperature and protolith composition. Lithos 2018, 310–311, 20–30.</p>

scholarly journals Age, provenance and tectonic setting of the high-grade Jequitinhonha Complex, Araçuaí Orogen, eastern Brazil

2016 ◽  
Vol 46 (2) ◽  
pp. 199-219 ◽  
Author(s):  
Tatiana Gonçalves Dias ◽  
Fabrício de Andrade Caxito ◽  
Antônio Carlos Pedrosa-Soares ◽  
Ross Stevenson ◽  
Ivo Dussin ◽  
...  
Keyword(s):  
Detrital Zircon ◽  
Tectonic Setting ◽  
Granulite Facies ◽  
Major And Trace Elements ◽  
Passive Margin ◽  
Published Data ◽  
The North ◽  
Basement Rocks ◽  
Data Yield ◽  
Araçuaí Orogen

ABSTRACT: The Jequitinhonha Complex of the northeastern Araçuaí orogen is an extensive sedimentary unit metamorphosed in the amphibolite-granulite facies transition around 580-545 Ma. The unit consists of Al-rich (kinzigitic) paragneisses with decametric intercalations of graphite gneisses and quartzites, and centimetric to metric lenses of calcsilicate rocks. A new detrital zircon U-Pb age spectrum is reported for a sample of quartzite, and whole-rock geochemical (major and trace elements, 9 samples) and Sm-Nd isotope data (10 samples) for Jequitinhonha Complex paragneiss. Together with published data these show that: (1) the geochemistry of paragneiss samples of the Jequitinhonha Complex are similar to those of passive margin sedimentary protoliths; (2) detrital zircon data yield U-Pb age populations between ca. 0.9 and 2.5 Ga; and (3) Sm-Nd TDM model ages range from 1.6 to 1.8 Ga and εNd(575 Ma) around -7.5. The data reveal a mixture of Cryogenian to Mesoproterozoic rift-related igneous rocks with the Palaeoproterozoic-Archaean basement rocks of the São Francisco-Congo palaeocontinent as the main source areas, and also support the correlation between the Jequitinhonha Complex and the passive margin units of the upper Macaúbas Group, constituting the precursor basin of the orogen. Our results, with the absence of ophiolites in the Jequitinhonha Complex, reinforce the interpretation that the São Francisco-Congo palaeocontinent was not divided to the north of the focused region, suggesting an ensialic termination of a gulf during the Neoproterozoic.

Isotope-Geochemical Evidence of the Nature of the Protoliths of Diamondiferous Rocks of the Kokchetav Subduction–Collision Zone (Northern Kazakhstan)

2021 ◽  
Vol 62 (5) ◽  
pp. 547-556
Author(s):  
V.S. Shatsky ◽  
A.L. Ragozin ◽  
S.Yu. Skuzovatov ◽  
O.A. Kozmenko ◽  
E. Yagoutz
Keyword(s):  
Partial Melting ◽  
Granite Gneiss ◽  
Granulite Facies ◽  
Ultrahigh Pressure ◽  
High Alumina ◽  
Geochemical Evidence ◽  
Ultrahigh Pressure Metamorphism ◽  
Collision Zone ◽  
Basement Rocks ◽  
Silicate Garnet

Abstract —The isotope-geochemical features of diamondiferous metamorphic rocks of the Kokchetav subduction–collision zone (KSCZ) show that both the basement rocks and the sediments of the Kokchetav massif were their protoliths. A whole-rock Sm–Nd isochron from the diamondiferous calc-silicate, garnet–pyroxene rocks and migmatized granite-gneisses of the western block of the KSCZ yielded an age of 1116 ± 14 Ma, while an age of 1.2–1.1 Ga was obtained by U–Pb dating of zircons from the granite-gneiss basement of the Kokchetav microcontinent. Based on these data, we assume that the protoliths of the calc-silicate, garnet–pyroxene rocks and the granite-gneisses of the KSCZ were the basement rocks sharing an initially single Nd source, which was not influenced by high- to ultrahigh-pressure metamorphism (~530 Ma). Therefore, their geochemical features are probably not directly related to ultrahigh-pressure metamorphism. The corresponding rock associations lack isotope-geochemical evidence of partial melting that would occur during ultrahigh-pressure metamorphism, which suggesting that they were metamorphosed under granulite-facies conditions. At the same time, the high-alumina diamondiferous rocks of the Barchi area (garnet–kyanite–mica schists and granofelses), which were depleted to different degrees in light rare-earth elements (REE) and K, have yielded a Sm–Nd whole-rock isochron age of 507 ± 10 Ma indicating partial melting of these rocks during their exhumation stage. The close ɛNd (1100) values of the basement rocks and garnet–kyanite–mica schist with geochemical characteristics arguing against its depletion during high-pressure metamorphism indicate that the basement rocks were a crustal source for high-alumina sediments.

Mineral Chemistry and Geothermobarometry of Amphibolite-Granulite Facies Basement Rocks Concealed Below Deccan Volcanic Covered 1993 Killari Earthquake Region, Maharashtra, India

2021 ◽  
Vol 97 (11) ◽  
pp. 1331-1339
Author(s):  
Priyanka Tripathi ◽  
H. K. Sachan ◽  
V. Rajagopalan ◽  
O. P. Pandey ◽  
Sujeet Kumar Dwivedi ◽  
...  
Keyword(s):  
Granulite Facies ◽  
Mineral Chemistry ◽  
Basement Rocks

The structure, metamorphism, and development of the Boothia Arch, Arctic Canada

1969 ◽  
Vol 6 (4) ◽  
pp. 525-543 ◽  
Author(s):  
Richard L. Brown ◽  
Ian W. D. Dalziel ◽  
Brian R. Rust
Keyword(s):  
Cross Sections ◽  
Deep Level ◽  
Granulite Facies ◽  
Second Phase ◽  
Early Devonian ◽  
Basement Rocks ◽  
Clastic Sediments ◽  
Deltaic Sedimentation ◽  
Positive Feature ◽  
Planar Fabric

The Precambrian basement rocks of the Boothia Arch exhibit three phases of folding characteristic of deep-level deformation in mobile belts. Structural cross-sections demonstrate that the geometry of compositional layering and regionally parallel axial-plane foliation of first-phase folds is controlled primarily by structures of the second phase.The basement gneisses contain assemblages of the amphibolite–granulite transitional facies. The felsic gneisses exhibit a planar fabric clearly defined by nearly oblate quartz grains, usually considered to be typical of "granulite" facies rocks. In the Boothia Arch this foliation is an axial surface structure formed during the second fold phase. Fabric studies suggest that anhydrous assemblages stable in the granulite facies prior to the second phase of deformation were replaced during this phase by hydrous assemblages characteristic of the amphibolite-granulite transitional facies.The Boothia Arch was a source of clastic sediments during three periods of cover-rock deposition. It was a mild positive feature in Aston times (late Proterozoic or early Paleozoic), and was rapidly uplifted along north-south trends during late Silurian and early Devonian times to produce continental clastic facies of the Peel Sound Formation symmetrically related to the arch. The limited Cretaceous–Tertiary record suggests irregular uplift and localized deltaic sedimentation. At other times the Boothia Arch was insignificant as a source of detritus, and carbonates were deposited over the area.The north–south strike of compositional banding and axial surfaces of the first- and second-phase folds in the basement parallels the axis of the arch and axial surfaces of folds in the cover rocks. Also, fracture patterns in the basement and cover rocks are similar. Beyond this there is no obvious relationship between the internal structure of the basement and the later development of the arch.

scholarly journals Elastic properties of granulite facies rocks of Mahabalipuram, Tamil Nadu, India

2006 ◽  
Vol 115 (6) ◽  
pp. 673-683 ◽  
Author(s):  
M. V. M. S. Rao ◽  
K. J. Prasanna Lakshmi ◽  
L. P. Sarma ◽  
K. B. Chary
Keyword(s):  
Elastic Properties ◽  
Tamil Nadu ◽  
Granulite Facies

scholarly journals Post-kinematic diorite intrusions in Archaean basement rocks around outer Fiskefjord, southern West Greenland

1991 ◽  
Vol 39 ◽  
pp. 167-177
Author(s):  
A. A. Garde
Keyword(s):  
Trace Element ◽  
Final Stage ◽  
Precious Metals ◽  
Granulite Facies ◽  
High Grade ◽  
West Greenland ◽  
Mafic Intrusions ◽  
Basement Rocks ◽  
High Grade Metamorphism ◽  
Crust Deformation

About twenty small dioritic intrusions around outer Fiskefjord, southern West Greenland, which are undeformed and unmigmatised, mark the final stage in middle Archaean accretion of continental crust, deformation and high-grade metamorphism in the Akia terrane. The diorites were emplaced into hot tonalitic gneisses, some of which were thoroughly retrograded from granulite facies prior to diorite intrusion. The diorites are themselves sporadically retrograded. A conventional zircon U-Pb age of 3017 + 12/-10 Ma has been obtained from one of the diorites. The diorites have SiO2 contents between ea. 52 and 58 wt. % and up to ea. 15% MgO, and some of them border on leuconorite or anorthosite, with normative plagioclase contents up to ea. 85 wt. % . Trace element compositions are characterised by elevated amounts of Zn, Co, Ni, and especially Cr, but low contents of several LIL elements, and they were probably contaminated with sialic crust. The diorite intrusions may be related to a group of a more mafic intrusions with anomalous contents of precious metals, forming the "norite belt" some 50 km north of Fiskefjord.

Sign in / Sign up

Export Citation Format

Share Document