Chapter 9 Continental magmatic arc and siliciclastic sedimentation in the far-field part of a 1.7 Ga accretionary orogen

2020 ◽  
Vol 50 (1) ◽  
pp. 253-268 ◽  
Author(s):  
Magnus Ripa ◽  
Michael B. Stephens
Keyword(s):  
Volcanic Rocks ◽  
Source Rocks ◽  
Far Field ◽  
Magmatic Arc ◽  
Enriched Mantle ◽  
West Central ◽  
High K ◽  
Arc Setting ◽  
Continental Magmatic Arc ◽  
Orogenic Belts

AbstractTrachyandesitic to trachybasaltic lavas, interlayered siliciclastic sedimentary rocks and subaerial ignimbrites with a rhyolitic to trachydacitic composition lie unconformably above metamorphic rocks in west-central Sweden. These volcanic rocks erupted at 1711 + 7/−6 to 1691 ± 5 Ma and belong to a high-K, calc-alkaline to shoshonitic suite deposited in a continental arc setting. Positive ɛNd values and Nb/Yb ratios in the trachyandesitic to trachybasaltic rocks indicate an enriched mantle source. Coeval, 1710 ± 11 to 1681 ± 16 Ma plutonic and subvolcanic rocks are mainly granitic or quartz syenitic in composition. Subordinate components include quartz monzonite, quartz monzodiorite and monzogabbro or gabbro. ɛNd values in the range −1.0 to + 1.1 overlap with those in the inferred 1.9–1.8 Ga source rocks. All these rocks belong to the youngest phase of the lithodemic unit referred to as the Transscandinavian Igneous Belt. This magmatic province extends in a roughly NNW direction for at least 900 km, variably deformed and metamorphosed equivalents occurring inside and beneath younger orogenic belts to the south (Sveconorwegian) and north (Caledonian). The part of the province in west-central Sweden addressed here represents a far-field and shallow crustal component in this 1.7 Ga accretionary orogenic system.

scholarly journals Calc-alkaline volcanic rocks and zircon ages of the late Tonian: early Cryogenian arc-related Big Naryn Complex in the Eastern Djetim-Too Range, Middle Tianshan block, Kyrgyzstan

2020 ◽  
Author(s):  
Baiansuluu Terbishalieva ◽  
Martin Jan Timmerman ◽  
Alexander Mikolaichuk ◽  
Uwe Altenberger ◽  
Jiří Sláma ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Metamorphic Rocks ◽  
Magmatic Arc ◽  
Lower Member ◽  
Short Time Span ◽  
Zircon Crystallization ◽  
Arc Setting ◽  
Late Neoproterozoic ◽  
Continental Magmatic Arc ◽  
Short Time

AbstractThe Big Naryn Complex (BNC) in the East Djetim-Too Range of the Kyrgyz Middle Tianshan block is a tectonized, at least 2 km thick sequence of predominantly felsic to intermediate volcanic rocks intruded by porphyric rhyolite sills. It overlies a basement of metamorphic rocks and is overlain by late Neoproterozoic Djetim-Too Formation sediments; these also occur as tectonic intercalations in the BNC. The up to ca. 1100 m thick Lower Member is composed of predominantly rhyolites-to-dacites and minor basalts, while the at least 900 m thick pyroclastic Upper Member is dominated by rhyolitic-to-dacitic ignimbrites. Porphyric rhyolite sills are concentrated at the top of the Lower Member. A Lower Member rhyolite and a sill sample have LA-ICP-MS U–Pb zircon crystallization ages of 726.1 ± 2.2 Ma and 720.3 ± 6.5 Ma, respectively, showing that most of the magmatism occurred within a short time span in the late Tonian–early Cryogenian. Inherited zircons in the sill sample have Neoarchean (2.63, 2.64 Ga), Paleo- (2.33–1.81 Ga), Meso- (1.55 Ga), and Neoproterozoic (ca. 815 Ma) ages, and were derived from a heterogeneous Kuilyu Complex basement. A 1751 ± 7 Ma 40Ar/39Ar age for amphibole from metagabbro is the age of cooling subsequent to Paleoproterozoic metamorphism of the Kuilyu Complex. The large amount of pyroclastic rocks, and their major and trace element compositions, the presence of Neoarchean to Neoproterozoic inherited zircons and a depositional basement of metamorphic rocks point to formation of the BNC in a continental magmatic arc setting.

scholarly journals PRE-ALPINE MIGMATITIC ROCKS AND ACID TO INTERMEDIATE ORTHOGNEISSES IN PENTELIKON MOUNTAIN (NE ATTICA, GREECE)

2004 ◽  
Vol 36 (1) ◽  
pp. 542
Author(s):  
I. Baziotis ◽  
E. Mposkos ◽  
V. Perdikatsis
Keyword(s):  
Broad Area ◽  
Magmatic Arc ◽  
Eu Anomaly ◽  
High K ◽  
Arc Setting ◽  
Ree Patterns

In the broad area of Pentelikon Mountain, which is part of the Attic-Cycladic crystalline belt, metamigmatites and orthogneisses occur as tectonic slices within the calc-schists or between calcschists and marbles. In the metamigmatites relic of migmatitic fabrics, comprising leucosomes and melanosomes, and cross-cutting aplitic and pegmatitic dykes are still preserved. The orthogneisses have dioritic to granitic composition. They are interpreted to be probably formed in a magmatic arc setting. Granitic orthogneisses show high-K contents and are enriched in LILEs and depleted in HFSEs. They also exhibit fractionated REE patterns with slight to strong negative Eu anomaly. The exceptionally high K2O contents (>7%) and the very low Na2Û contents (0.4-0.98 wt%) of certain phengite-orthogneisses with ultramylonitic textures are attributed to metasomatic processes that occurred during ultramylonitization.

scholarly journals Petrogenesis and U-Pb and Sm-Nd geochronology of the Taquaral granite: record of an orosirian continental magmatic arc in the region of Corumba - MS

2015 ◽  
Vol 45 (3) ◽  
pp. 431-451 ◽  
Author(s):  
Letícia Alexandre Redes ◽  
Maria Zélia Aguiar de Sousa ◽  
Amarildo Salina Ruiz ◽  
Jean-Michel Lafon
Keyword(s):  
Geochemical Data ◽  
Alkaline Magmatism ◽  
Alluvial Deposits ◽  
Mato Grosso ◽  
Microgranular Enclave ◽  
Magmatic Arc ◽  
Rock Types ◽  
High K ◽  
Continental Magmatic Arc ◽  
Shrimp Zircon

The Taquaral Granite is located on southern Amazon Craton in the region of Corumbá, westernmost part of the Brazilian state of Mato Grosso do Sul (MS), near Brazil-Bolivia frontier. This intrusion of batholitic dimensions is partially covered by sedimentary rocks of the Urucum, Tamengo Bocaina and Pantanal formations and Alluvial Deposits. The rock types are classified as quartz-monzodiorites, granodiorites, quartz-monzonites, monzo and syenogranites. There are two groups of enclaves genetically and compositionally different: one corresponds to mafic xenoliths and the second is identified as felsic microgranular enclave. Two deformation phases are observed: one ductile (F1) and the other brittle (F2). Geochemical data indicate intermediate to acidic composition for these rocks and a medium to high-K, metaluminous to peraluminous calk-alkaline magmatism, suggesting also their emplacement into magmatic arc settings. SHRIMP zircon U-Pb geochronological data of these granites reveals a crystallization age of 1861 ± 5.3 Ma. Whole rock Sm-Nd analyses provided εNd(1,86 Ga) values of -1.48 and -1.28 and TDM model ages of 2.32 and 2.25 Ga, likely indicating a Ryacian crustal source. Here we conclude that Taquaral Granite represents a magmatic episode generated at the end of the Orosirian, as a part of the Amoguija Magmatic Arc.

scholarly journals Oligocene-Pleistocene Paleogeography within Banyumas Basin and implication to petroleum potential

2018 ◽  
Vol 1 ◽  
pp. 00006 ◽  
Author(s):  
Eko Bayu Purwasatriya ◽  
Sugeng Sapto Surjono ◽  
Donatus Hendra Amijaya
Keyword(s):  
Depositional Environment ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Source Rocks ◽  
Petroleum Potential ◽  
Magmatic Arc ◽  
The North ◽  
Potential Source ◽  
Back Arc ◽  
Exploration Activity

<p>This study attempts to reconstruct paleogeography of Banyumas Basin in association with magmatic arc evolution and its implication to petroleum potential. Based on the volcanic rocks distribution, their association and relatives age, there are three alignments of a magmatic arc, that are: (1) Oligo-Miocene arc in the south (2) Mio-Pliocene arc in the middle (3) Plio-Pleistocene arc in the north. The consequences of the magmatic arc movement were tectonic setting changing during Oligocene to Pleistocene, as well as their paleogeography. During Oligo-Miocene where magmatic arc existed in the southern part, the Banyumas tectonic setting was a back-arc basin. This tectonic setting was changing to intra-arc basin during Mio-Pliocene and subsequently to fore-arc basin since Plio-Pleistocene until today. Back-arc basin is the most suitable paleogeography to create a depositional environment for potential source rocks. Exploration activity to prove the existence of source rocks during Oligo-Miocene is needed to reveal petroleum potential in Banyumas Basin.<br></p>

scholarly journals Low-P/High-T pre-Alpine metamorphism and medium-P Alpine overprint of the pelagonian zone documented in high-alumina metapelites from the Vernon massif, Western Macedonia, Northern Greece

2001 ◽  
Vol 34 (3) ◽  
pp. 949 ◽  
Author(s):  
E. MPOSKOS ◽  
D. K. KOSTOPOULOS ◽  
A. KROHE
Keyword(s):  
High Alumina ◽  
Northern Greece ◽  
Geothermal Gradients ◽  
Magmatic Arc ◽  
Northeastern Part ◽  
Alpine Metamorphism ◽  
Arc Setting ◽  
Continental Magmatic Arc ◽  
Pelagonian Zone ◽  
First Time

A low-P / high-T metamorphic event (andalusite-sillimanite series) of pre-Alpine age, identified here for the first time, has affected the metapelitic rocks of the Vernon Massif. P-T conditions of metamorphism in the western part of the Massif are estimated at -2.5 kb / 600-610°C, while in the northeastern part they are estimated to have exceeded 4.5 kb / 640°C respectively. Such P-T conditions correspond to geothermal gradients of 68°C/ km and 40°C/km for the western and the northeastern parts of the Massif respectively. The inferred steep geothermal gradients require transport of heat from deeper to shallower levels within the crust, achieved via magmatic intrusions in a continental magmatic arc setting. Alpine overprinting is characterized by P-T metamorphic conditions of ~6 kb / <350°C in the western part and ~9 kb / <570°C in the northeastern part of the Massif respectively. Low-P / high-T metamorphic rocks, occurring as klippen in the Cyclades and as blocks in the ophiolitic milanges of Crete, are interpreted as remnants of the pre-Alpine Pelagonian nappe similar to those occurring in the Vernon Massif.

Geochemistry and geodynamic constraint of volcanic and plutonic magmatism within the Banfora Belt (Burkina-Faso, West-Africa): contribution to mineral exploration

2020 ◽  
pp. SP502-2019-86
Author(s):  
Hermann Ilboudo ◽  
Sâga Sawadogo ◽  
Gounwendmanaghre Hubert Zongo ◽  
Seta Naba ◽  
Urbain Wenmenga ◽  
...  
Keyword(s):  
Fractional Crystallization ◽  
Mineral Exploration ◽  
Volcanic Rocks ◽  
Mafic Magma ◽  
Calc Alkaline ◽  
High K ◽  
Tectonic Settings ◽  
Arc Setting ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks

AbstractPredominant volcano-plutonic (mafic–felsic) activity is expressed in the eastern Banfora Belt. The geochemical signature shows different geodynamic settings: (1) mafic rocks are tholeiitic, subalkaline and show high-Mg tendency, whereas pyroxenolite (MgO c. 15.4 wt%) has komatiite affinity; (2) felsic volcanic rocks are subalkaline; and (3) granitoids surrounding the Banfora Belt are alkaline to calc-alkaline, high K, peraluminous to metaluminous. The geochemistry of mafic volcanic rocks shows an unusual evolution from Mid Oceanic Ridge Basalt to Arc-related. The Western Granite and Eastern Granites were emplaced by fractional crystallization and partial melting, respectively, but sourced from igneous protolith (I-type magma) in a volcanic arc setting. The Sodingue granite was emplaced by fractional crystallization from A-type magma in a ‘within-plate setting’. Two-mica S-type granites located at the central portion of the belt relate to syn-collisional fractional crystallization. The paper highlights the complexity of the magma process through a diversity of sources, geochemical patterns and tectonic settings. An emphasis on the komatiite affinity of mafic magma is a challenge for related commodities, such as copper and gold resources.

scholarly journals Magmatic Evolution and Compositional Characteristics of Tertiary Volcanic Rocks Associated with the Venarch Manganese Mineralization, Sw Qom, Central Iran

2015 ◽  
Vol 19 (2) ◽  
pp. 141-145 ◽  
Author(s):  
Mansoureh Mahdavi ◽  
Rahim Dabiri ◽  
Elham Shah Hosseini
Keyword(s):  
Subduction Zones ◽  
Volcanic Rocks ◽  
Ore Deposits ◽  
Geochemical Data ◽  
Magmatic Arc ◽  
High K ◽  
Ore Minerals ◽  
Manganese Mineralization ◽  
Host Rocks ◽  
Mn Ore

<p>The manganese (Mn) deposits of Iran date from late Proterozoic to Pliocene but the major high-grade Mn ore deposits are associated with tertiary basic to intermediate volcanic rocks. The Venarch Mn deposit is located in the SW Qom city and considered as one of the largest in Iran. The Mn mineralization is mostly hosted by Eocene high-k volcanic and pyroclastic rocks of Urmia-Dokhtar Magmatic Arc (UDMA). The study area mainly consists of basalt, trachybasalt, andesite, and basaltic-andesite that are intruded by Eocene-Oligocene monzodiorite, monzonite, and granodiorite intrusions. The Venarch Mn ore bodies are mostly hosted by shale beds and wrapped by altered mega-porphyritic andesites and spilitic lavas both in the foot and hanging walls. Petrographic studies show that the principal ore minerals are pyrolusite, psilomelane, and other Mn-oxides,and quartz and calcite were determined as the gang minerals. Integration of field geology, petrography, and geochemical results suggest a hydrothermal origin for the Venarch Mn deposit. Our geochemical data furthermore suggest the volcanic host rocks to be comparable to high-K series of subduction zones.</p><p> </p><p><strong>Evolución Magmática y Características de Composición en Rocas Volcánicas Terciarias Asociadas con la Mineralización de Manganeso en la Mina de Venarch, al Suroeste de Qom, en la Región Central de Irán</strong></p><p> </p><p><strong>Resumen</strong></p>Los yacimientos de manganeso (Mn) en Irán datan del Proterozoico tardío hasta el Plioceno, pero el mayor grado de los depósitos de la mena de manganeso se asocian a rocas volcánicas básicas a intermedias de edad Terciaria. El yacimiento de manganeso en la mina de Venarch se localiza al suroeste de la ciudad de Qom y está considerado como uno de los más grandes de Irán. La mineralización de manganeso se presenta en su mayoría en las rocas piroclásticas y volcánicas de alto contenido de K del Eoceno en el Arco Magmático Urmia-Dokhtar (UDMA, en inglés). El área de estudio presenta basaltos, traquibasaltos, andesitas y andesitas basálticas que están intruidas por monzodioritas, monzonitas y granodioritas del Eoceno-Oligoceno. Los cuerpos de mineral de manganeso en Venarch en su mayoría están dentro de capas de pizarra y envueltos por lavas espiliticas y andesitas megaporfiroides tanto en las paredes del piso como en las colgantes. Los estudios petrográficos muestran que los minerales son pirolusitas, silomelanas y otros óxidos de manganeso, mientras que los cuarzos y las calcitas constituyen los minerales de ganga. La integración de los trabajos de geología de campo, petrográficos y geoquímicos sugieren un origen hidrotérmal del yacimiento de manganeso de Venarch. Los datos geoquímicos de este estudio también sugieren que la roca volcánica anfitriona es comparable con las series ricas en K de las zonas de subducción.</p>

Volcanism of shoshonite to high-K andesite affinity in an Archean are environment, Oxford Lake, Manitoba

1982 ◽  
Vol 19 (1) ◽  
pp. 55-67 ◽  
Author(s):  
C. Brooks ◽  
J. Ludden ◽  
Y. Pigeon ◽  
J. J. M. W. Hubregtse
Keyword(s):  
Incompatible Element ◽  
Source Region ◽  
Short Interval ◽  
Volcanic Rocks ◽  
Element Abundances ◽  
Mantle Source Region ◽  
High K ◽  
Tectonic Settings ◽  
Arc Setting ◽  
Amphibole Fractionation

Volcanic rocks of the Archean Oxford Lake Group are characterized by a stratigraphic progression from mafic to felsic compositions, accompanied by a systematic decrease in incompatible element abundances. This, coupled with high abundances of Sr, Rb, K2O, and La, high (La/Yb)n, and unfractionated (flat to concave) heavy-REE (rare earth element) profiles, distinguishes these rocks as an Archean shoshonite to high-K andesite – dacite–rhyolite series, directly comparable to modern analogues formed in convergent tectonic settings. The trace-element data support a model of petrogenesis in which an Archean mantle source region was modified by volatiles rich in large-ion-lithophile elements, the modified mantle was subjected to partial melting forming a parental liquid of shoshonitic character, and this liquid principally underwent amphibole fractionation to form the evolved rock compositions. This process is envisaged as terminal magmatism during the final (senile) stage of activity in an arc setting. The Rb–Sr age (2650 ± 80 Ma) and initial-Sr ratio (0.70145 ± 38) of the Oxford Lake Group are in accord with this model; when coupled with the 2.7 Ga age for the underlying Hayes River Group volcanics, these data indicate a short interval (<50 Ma?) for Archean crustal development in the area.

Studi Awal Geologi di Daerah Beruang Kanan Kabupaten Gunung Mas Propinsi Kalimantan Tengah

PROMINE ◽  
2018 ◽  
Vol 6 (1) ◽  
pp. 1-11
Author(s):  
Retno Anjarwati ◽  
Arifudin Idrus ◽  
Lucas Donny Setijadji
Keyword(s):  
Gold Mineralization ◽  
Volcanic Rocks ◽  
Gold Deposits ◽  
Central Kalimantan ◽  
Magmatic Arc ◽  
Tertiary Sediment ◽  
Copper Gold ◽  
Regional Tectonic ◽  
Mineralization Processes ◽  
High Yields

The regional tectonic conditions of the KSK Contract of Work are located in the mid-Tertiary magmatic arc (Carlile and Mitchell, 1994) which host a number of epithermal gold deposits (eg, Kelian, Indon, Muro) and significant prospects such as Muyup, Masupa Ria, Gunung Mas and Mirah. Copper-gold mineralization in the KSK Contract of Work is associated with a number of intrusions that have occupied the shallow-scale crust at the Mesozoic metamorphic intercellular junction to the south and continuously into the Lower Tertiary sediment toward the water. This intrusion is interpreted to be part of the Oligocene arc of Central Kalimantan (in Carlile and Mitchell 1994) Volcanic rocks and associated volcanoes are older than intrusions, possibly aged Cretaceous and exposed together with all three contacts (Carlile and Mitchell, 1994) some researchers contribute details about the geological and mineralogical background, and some papers for that are published for the Beruang Kanan region and beyond but no one can confirm the genesis type of the Beruang Kanan region The mineralization of the Beruang Kanan area is generally composed by high yields of epithermal sulphide mineralization. with Cu-Au mineralization This high epithermal sulphide deposition coats the upper part of the Cu-Au porphyry precipitate associated with mineralization processes that are generally controlled by the structure

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