Komparasi Geokimia Batuan Gunung Api Kuarter dan Tersier di Tepian Selatan Lampung

ABSTRAK Keterdapatan batuan gunung api di Sumatra diakibatkan oleh penunjaman Lempeng Samudra India-Australia ke bawah Lempeng West Sumatra sejak Eosen. Tanggamus adalah kabupaten di ujung selatan Lampung dengan keterdapatan beberapa unit batuan gunung api berumur Tersier maupun Kuarter. Studi ini bertujuan untuk membandingkan komposisi geokimia batuan gunung api Tersier Formasi Hulusimpang dengan batuan gunung api Kuarter Gunung Tanggamus. Perangkat XRF dan ICP-MS dimanfaatkan untuk mengetahui kadar oksida utama, unsur jejak, dan unsur tanah jarang pada penelitian ini. Berdasarkan karakter geokimia, sampel dari Formasi Hulusimpang adalah batuan gunung api kalk-alkali, metalumina hingga peralumina, dan dalam rentang trakiandesit basaltik hingga riolit. Sampel batuan gunung api berumur Kuarter berada pada rentang kadar silika yang lebih sempit dan cenderung metalumina. Studi ini membuktikan bahwa kedua kelompok batuan berasal dari magma yang sama, tetapi dengan kontaminasi kerak selama diferensiasi. Proses pembentukan yang berbeda pada kedua kelompok batuan diperjelas oleh derajat kemiringan kurva diagram laba-laba UTJ dan jenis anomali Eu.ABSTRACT The presence of volcanic rocks in Sumatra is due to the subduction of the Indian-Australian Ocean Plate under the West Sumatra Plate since the Eocene. Tanggamus Regency situated at the southern edge of Lampung with the occurrence of several Tertiary and Quaternary volcanic rock units. The aim of this study is to compare the geochemical composition of Tertiary volcanic rocks from the Hulusimpang Formation and Quaternary volcanic rocks from Mount Tanggamus in the Tanggamus Regency. XRF and ICP-MS devices were used to determine the compositions of major oxides, trace elements, and rare earth elements in this study. Based on geochemical characters, samples from the Hulusimpang Formation are calc-alkaline volcanic rocks, metaluminous to peraluminous, and in the basaltic trachyandesite to rhyolite ranges. Quaternary samples are in a narrower range of silica content and tend to be metaluminous. This study proves that the two rock groups originate from the same magma but with crustal contamination during differentiation. The two volcanic should experience through different formation processes based on the slope of the heavy-REE and the type of Eu anomaly.

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Petrology and Geochemistry of The Volcanic Arc Tarusan Pluton in Comparison to Lolo Pluton, West Sumatra

Jurnal Geologi dan Sumberdaya Mineral ◽

10.33332/jgsm.geologi.v20i4.471 ◽

2019 ◽

Vol 20 (4) ◽

pp. 199

Author(s):

Ronaldo Irzon ◽

Ildrem Syafri ◽

Irfani Agustiany ◽

Arief Prabowo ◽

Purnama Sendjaja

Keyword(s):

Microscopic Analysis ◽

Calc Alkaline ◽

Magma Evolution ◽

Peraluminous Granite ◽

Volcanic Arc ◽

Eu Anomaly ◽

Icp Ms ◽

West Sumatra ◽

Petrology And Geochemistry ◽

Geochemistry Characteristics

The Volcanic Arc Suite is the group of batholiths in the range of the Barisan Mountains and mostly denotes I-type affinity. Previous investigations of the intrusions in West Sumatra emphasized the crystallization age without completing geochemistry characteristics. No former study discussed a pluton which mapped in the Kota XI Tarusan District. This study explains the geochemistry and petrology of the Tarusan Pluton using polarized microscope, XRF, and ICP-MS at the Center for Geology Survey of Indonesia. The microscopic analysis confirms the granite character of the samples. Although both plutons are identified as I-type calc-alkaline series, the Tarusan Pluton is peraluminous granite whilst the Lolo Pluton denotes wider range from metaluminous to peraluminous of granodiorite to granite. Both the plutons are clearly classified as volcanic arc granitoid in the correlation to Volcanic Arc Suite of Sumatra. Negative Ba, Nb, and P anomalies together with positive K, Nd, and Y anomalies are pronounced on the two felsic intrusions. Negative Eu anomaly on the Tarusan Pluton but the positive one at the Lolo Pluton might explain different magma evolution process.Keywords: volcanic arc granite, geochemistry, Tarusan Pluton, Lolo Pluton.

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Petrology and Geochemistry of The Volcanic Arc Tarusan Pluton in Comparison to Lolo Pluton, West Sumatra

Jurnal Geologi dan Sumberdaya Mineral ◽

10.33332/jgsm.geologi.20.4.199-210 ◽

2019 ◽

Vol 20 (4) ◽

pp. 199

Author(s):

Ronaldo Irzon ◽

Ildrem Syafri ◽

Irfani Agustiany ◽

Arief Prabowo ◽

Purnama Sendjaja

Keyword(s):

Microscopic Analysis ◽

Calc Alkaline ◽

Magma Evolution ◽

Peraluminous Granite ◽

Volcanic Arc ◽

Eu Anomaly ◽

Icp Ms ◽

West Sumatra ◽

Petrology And Geochemistry ◽

Geochemistry Characteristics

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Rare earth element concentrations in Quaternary volcanic rocks of southwestern British Columbia

Canadian Journal of Earth Sciences ◽

10.1139/e84-079 ◽

1984 ◽

Vol 21 (6) ◽

pp. 731-736 ◽

Cited By ~ 4

Author(s):

Nathan L. Green ◽

Paul Henderson

Keyword(s):

British Columbia ◽

Earth Element ◽

Volcanic Rocks ◽

Crustal Contamination ◽

Lake Area ◽

Calc Alkaline ◽

Lower Light ◽

The Individual ◽

High Level ◽

Ree Patterns

A suite of hy-normative hawaiites, ne-normative mugearite, and calc-alkaline andesitic rocks from the Garibaldi Lake area exhibits fractionated, slightly concave-upward REE patterns (CeN/YbN = 4.5–15), heavy REE contents about 5–10 times the chondritic abundances, and no Eu anomalies. It is unlikely that the REE patterns provide information concerning partial melting conditions beneath southwestern British Columbia because they have probably been modified substantially by upper crustal processes including crustal contamination and (or) crystal fractionation. The REE contents of the Garibaldi Lake lavas are not incompatible with previous interpretations that (1) the hawaiites have undergone considerable fractionation of olivine, plagioclase, and clinopyroxene; and (2) the individual andesitic suites were derived from separate batches of chemically distinct magma that evolved along different high-level crystallization trends. In general, however, the andesites are characterized by lower light REE contents than the basaltic andesites. These differences in LREE abundances may reflect different amounts of LREE-rich accessory phases, such as apatite, sphene, or allanite, assimilated from the underlying quartz diorites.

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Sr and O isotope constraints on source and crustal contamination in the high-K calc-alkaline and shoshonitic neogene volcanic rocks of SE Spain

Lithos ◽

10.1016/s0024-4937(99)00003-1 ◽

1999 ◽

Vol 46 (4) ◽

pp. 773-802 ◽

Cited By ~ 109

Author(s):

R. Benito ◽

J. López-Ruiz ◽

J.M. Cebriá ◽

J. Hertogen ◽

M. Doblas ◽

...

Keyword(s):

Volcanic Rocks ◽

Crustal Contamination ◽

Calc Alkaline ◽

Se Spain ◽

High K ◽

O Isotope

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Study of Petrogenesis and Tectonomagmatic Environments of Eocene Calc-Alkaline Volcanic Units in South and Southeast of Beroni Village in Southwest Ardestan (Isfahan)

Current World Environment ◽

10.12944/cwe.10.special-issue1.86 ◽

2015 ◽

Vol 10 (Special-Issue1) ◽

pp. 719-726

Author(s):

Sayyed Roshan ◽

Ali Khan Nasr Esfahani

Keyword(s):

Volcanic Rocks ◽

Crustal Contamination ◽

Hydrothermal Solution ◽

Hydrothermal Solutions ◽

Calc Alkaline ◽

Silica Rocks ◽

Calcium Magnesium ◽

Alkaline Magmas ◽

Host Rocks ◽

Lateral Segregation

The study area is located in south and southeast of Beroni Village. It contains volcanic rocks including andesitic-basaltic, pyroxene-bearing andesite, andesite, dacite, rhyodacite, rhyolites and Eocene-Oligocene ignimbrites. The volcanic rocks are cut by an intrusive mass with great spreading in the region. According to lithological studies, the calc-alkaline magmas in continental margin arcs are comprised of mantle and fluid crust. The basic elements in the volcanic rocks were studied in terms of petrological indices. According to the results, the metaluminous rocks underwent crustal contamination. Due to chemical reactions between the hydrothermal solution and volcanic host rocks, hydrothermal solutions in volcanic rocks penetrate the surrounding silica rocks and thus some elements such as zinc and barium diffuse in the rocks. In addition, calcium, magnesium and iron have been drawn inwards from the surrounding rocks causing lateral segregation.

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Permian lamprophyres from the Western Carpathians: a review

Geological Society London Special Publications ◽

10.1144/sp513-2020-237 ◽

2021 ◽

pp. SP513-2020-237

Author(s):

Ján Spišiak ◽

Lucia Vetráková ◽

David Chew ◽

Štefan Ferenc ◽

Viera Šimonová ◽

...

Keyword(s):

Hydrothermal Fluid ◽

Mineralogical Composition ◽

Western Carpathians ◽

Crustal Material ◽

Calc Alkaline ◽

Geochemical Composition ◽

Nd Isotope ◽

Icp Ms ◽

Compositional Variations ◽

Alkaline Lamprophyres

AbstractCalc-alkaline lamprophyres from the Western Carpathians occur as dykes and sills in the crystalline complexes (predominantly granites and gneisses) of the Tatric Unit. Some of the lamprophyre dykes have been strongly overprinted by tectonism and hydrothermal fluid ingress. They have a similar mineralogical composition, and they are comprised of clinopyroxene, amphibole, biotite and plagioclase. Based on their modal composition, they can be classified as spessartites and kersantites, and based on their geochemical composition, most of them are of calc-alkali type. Lamprophyres from individual core complexes (e.g. the Malá Fatra Mountains and Nízke Tatry Mountains) exhibit variable Nb, Ta and Sr–Nd isotope signatures. These differences are probably due to compositional variations in the mantle source and/or the lower crust at the site of lamprophyre melt generation, or variable incorporation of crustal material. The age of the lamprophyres is Permian (c. 265 Ma) based on U–Pb LA-ICP-MS dating of apatite micro-phenocrysts.

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Archean Glomeroporphyritic Basalts

Canadian Journal of Earth Sciences ◽

10.1139/e75-157 ◽

1975 ◽

Vol 12 (10) ◽

pp. 1770-1784 ◽

Cited By ~ 9

Author(s):

Nathan L. Green

Keyword(s):

Volcanic Rocks ◽

Silica Content ◽

Gradual Transition ◽

Calc Alkaline ◽

Near Surface ◽

Stratigraphic Position ◽

Major Chemical ◽

Felsic Volcanic ◽

Archean Greenstone Belts ◽

Volcanic Cycles

Feldsparphyric basalts commonly occur as a distinctive 'marker horizon' 300 to 500 m below the felsic volcanic units of many Archean greenstone belts. Within the Knee Lake greenstone belt, northern Manitoba, glomeroporphyritic basalts, characterized by large irregularly-shaped aggregates of plagioclase phenocrysts, occupy this stratigraphic position within the two lower-most volcanic cycles. A major chemical and/or tectonic break does not occur within the volcanic cycles, but rather, the chemical affinities of the Knee Lake volcanic rocks changes gradually (at a silica content of approximately 55%) from tholeiitic to calc-alkaline with increasing stratigraphic height. The accumulation of plagioclase phenocrysts suggests extensive crystal fractionation of the Knee Lake magmas. The gradual transition in affinity of the Knee Lake lavas from tholeiitic to calc-alkaline can be explained by near-surface fractionation under constant fO2 conditions.

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Origin of the High-K Tertiary magmatism in Northern Greece: Implications for mantle geochemistry and geotectonic setting.

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.11017 ◽

2013 ◽

Vol 47 (1) ◽

pp. 416

Author(s):

K. Pipera ◽

A. Koroneos ◽

T. Soldatos ◽

G. Poli ◽

G. Christofides

Keyword(s):

Mantle Source ◽

Volcanic Rocks ◽

Crustal Contamination ◽

Calc Alkaline ◽

Northern Greece ◽

Mafic Rocks ◽

High K ◽

Depleted Mantle ◽

Subducted Oceanic Crust ◽

Compositional Variations

Tertiary plutonic and volcanic rocks cropping out in the Rhodope Massif (N. Greece) are studied using existing and new geochemical and isotopic data. Most of these rocks belong to the post-collisional magmatism formed as part of the prolonged extensional tectonics of the Rhodope region in Late Cretaceous– Paleogene time. This magmatism is considered to be of mantle origin; however, the character of the mantle source is controversial. Rock bulk chemistry and compositional variations show magmas with calc-alkaline to high-K calc-alkaline and shoshonitic features associated with magmatism at convergent margins. Initial 87Sr/86Sr, 143Nd/144Nd ratios, Pb isotopes and REE composition of the mafic rocks indicate mainly an enriched mantle source, even if some rocks indicate a depleted mantle source. Low- and High-K mafic members of these rocks coexist indicating a strongly heterogeneous mantle source. The High-K character of some of the mafic rocks is primarily strongly related to mantle enrichment by subduction-related components, rather than crustal contamination. The geochemical characteristics of the studied rocks (e.g Ba/Th,Th/Yb,Ba/La, U/Th, Ce/Pb) indicate that primarily sediments and/or sediment melts, rather than fluid released by the subducted oceanic crust controlled the source enrichment under the Rhodope Massif.

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Alteration of volcanic rocks and genesis of kaolin deposits in the Şile Region, northern İstanbul, Turkey. Part II: differential mobility of elements

Clay Minerals ◽

10.1180/0009855033840113 ◽

2003 ◽

Vol 38 (4) ◽

pp. 529-550 ◽

Cited By ~ 13

Author(s):

O. I. Ece ◽

Z.-E Nakagawa

Keyword(s):

Upper Cretaceous ◽

Source Region ◽

Volcanic Rocks ◽

Crustal Contamination ◽

Aegean Sea ◽

Calc Alkaline ◽

Tectonic Zone ◽

Nw Turkey ◽

Parent Rocks ◽

Kaolin Deposit

AbstractIn the area of S° ile, NW Turkey, Upper Cretaceous calc-alkaline volcanic rocks with compositions ranging from andesite to rhyolite have been recognized. The most widespread rocks of the suite are andesites, which can be grouped into altered and fresh. The oldest altered andesites are the parent rocks for the kaolin deposits of the study area. The Upper Cretaceous volcanic suite consists of spilite, basalt, andesite, trachyandesite, trachyandesitic and hyaloandesitic dacite, rhyolite lavas, tuffs and agglomerates. The highly altered andesites are composed of plagioclase, pyroxene, hornblende, biotite, augite and very fine opaque minerals. During the Turonian, an E –W trending extensional magmatic arc was developed in the Istanbul Tectonic Zone of the oceanic Western Black Sea basin and intermediate volcanic rocks were emplaced, mostly calc-alkaline andesites, suggesting multi-stage magmatism. The significant features of the andesites are: (1) enrichment of LILE (Rb, Ba, K) over HFSE (Zr, Nb, Hf, Ti, Th, U, Y) and LREE (La –Sm), resulting in high Ba/Nb, Th/Nb, Ba/La, K/Ti and Th/La ratios; (2) depletion of LREE over HFSE, MREE and HREE, generating high La/Nb, Ce/Ti, La/Sm and La/Y values; and (3) depletion of Nb, Sr and Ti; all of which are typical of island arc magmatism, with possible back arc signature. The Th-Hf-Ta diagram for tectonomagmatic classification shows that the S° ile calc-alkaline rocks are similar to volcanic rocks from the Mariana Arc, the Aeolian Arc of Salina, Italy, the Skaros island in the Aegean Sea and Sardinia's ignimbrites. Moreover, relatively low La/Th and Ce/Pb ratios suggest that the source region of volcanism was enriched in LILE with respect to REE, indicating crustal contamination during melting.Highly weathered andesitic rocks, rich in smectite, were transported gradually and deposited in a lacustrine basin, a coal-forming dysaerobic environment, in which they were subject to post-depositional alteration, or in situkaolinization, to form a kaolin deposit in the presence of humic and fulvic acids. The mobility of major and trace elements and REEs during the progressive kaolinization of andesitic materials has been investigated to reveal the geochemical characteristics of Upper Cretaceous volcanic parent rocks and to explain mineralogical processes in a kaolin deposit as a daughter rock ‘end-product’ . Alteration is characterized by the loss of Si, Fe, Ca, Na and K, and by the gain of Al, Ti, Zr and LOI. Moreover, Ho, Er and Yb are immobile, and Hf, Zr and Nb are mobile. Th and U are slightly enriched in clay horizons with respect to the andesitic rocks. In addition, Cr, Ga, Nb and Ta enrichments indicate variable sources of terrigenous sediments and differential mobilities of elements in lake waters rich in organic acids. The anatase concentration increases in the <2 mm size fractions as subspherical particles and these precipitate at acidic conditions (pH ≈ 5) during early diagenesis.

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Subduction-related magmatism of late Ordovician age in eastern England

Geological Magazine ◽

10.1017/s0016756800020951 ◽

1993 ◽

Vol 130 (5) ◽

pp. 647-656 ◽

Cited By ~ 44

Author(s):

T. C. Pharaoh ◽

T. S. Brewer ◽

P. C. Webb

Keyword(s):

Volcanic Rocks ◽

Oceanic Lithosphere ◽

Late Ordovician ◽

Igneous Rocks ◽

Calc Alkaline ◽

Geochemical Composition ◽

Magmatic Arc ◽

Hypabyssal Intrusions ◽

Deep Boreholes ◽

Intrusive Suite

AbstractDeep boreholes show that plutonic and volcanic igneous rocks comprise an important component of the Caledonian basement in eastern England. The isotopic compositions of these rocks reveal that many of them are of late Ordovician age (440–460 Ma), and their geochemical compositions suggest calc–alkaline affinities. The intermediate (diorite-tonalite) plutonic rocks are associated with a prominent northwest–southeast trending belt of aeromagnetic anomalies extending from Derby to St Ives, Hunts., which is interpreted to work the plutonic core of a calc-alkaline magmatic arc. It is inferred that this arc was generated by the subduction of oceanic lithosphere, possibly from the Tornquist Sea, in a south or southwest direction beneath the Midlands Microcraton in late Ordovician times. The age and geochemical composition of concealed Ordovician volcanic rocks in eastern England, and hypabyssal intrusions of the Midlands Minor Intrusive Suite in central England, is compatible with such a hypothesis.

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