Alkaline Series Research Articles

Mineralogical and Chemical Characterization of Acidic Pumices Outcrop North of Lake Van

In the present study, mineralogical, physical and chemical characteristics of the pumice located in North of Lake Van locations were investigated to find an applicability of them for cement and textile industry. Characterization studies of the pumice samples were carried out by thin section, SEM, XRF, XRD and FTIR analysis. In addition, the bulk density, Hard Grove Index (HGI), pozzolanic activity and reactive silica of the pumice samples were determined. The overall results showed that the pumice samples, which might be an eruption product of Mount Suphan, had an amorphous structure and rhyolite composition in high calc- alkaline series. The chemical compositions and physical properties indicated that the pumice samples could be used in cement and textile industry.

Evaluation of volatile iodine trapping in presence of contaminants: A periodic DFT study on cation exchanged-faujasite

Using periodic dispersion-corrected DFT calculations, the effect of potential inhibiting species (H2O, NO, CO, CH3Cl and Cl2) on the adsorption of iodine species (I2, CH3I) has been investigated over different monovalent (H, Li, Na, K, Rb, Cs, Cu and Ag) cation-exchanged faujasite. We have found out that van der Waals interactions play an important role and can contribute up to about 50% of the total adsorption energy for the alkaline series. Both computed adsorption energies at 0 K and adsorption enthalpies for temperatures ranging from 298 to 523 K highlight the following points: (i) CO and H2O have been identified as the most important inhibiting species; (ii) Hard cations such as H+ or Li+ are very sensitive to water whereas soft cations such as Cu+ and Ag+ can strongly adsorb I2 and CH3I. Therefore, Ag-FAU appears to be the most promising adsorbent in presence of all contaminants, except CO which can inhibit the adsorption of I2. These findings can help to improve the filtering devices used in nuclear plants to avoid the release of radioactive iodine in case of severe accident.

Space–time relationships between volcanic associations of different alkalinities: The Belogolovskii Massif, Sredinnyi Range, Kamchatka. Part II. Geochemistry of volcanic rocks and magma sources

Data are presented relating to volcanic series in the Belogolovskii Massif, Sredinnyi Range, Kamchatka. We discuss new geochronologic data, the distributions of rare elements and platinum elements in the rocks, and list the isotope characteristics of volcanic series with normal and moderate alkalinities. We show that the Late Pliocene to Early Pleistocene rocks that belong to the moderate alkaline series of the Belogolovskii volcanic massif are different from rocks in the normally alkaline series of the Late Miocene to Middle Pliocene volcanogenic basement in having higher concentrations of the HFSE and LILE components. We propose a model for the generation of moderate alkaline magmas involving a heterogeneous depleted and a heterogeneous enriched source of material. According to the isotope data, one of these sources may be the subducted oceanic lithosphere of the Pacific and the Commander-Islands type, while the other source was recycled material of the Indian MORB type.

Petrography, Mineralogy, and Origin of the Syenite Pegmatitic Segregation Veins From La Peña Alkaline Complex, Mendoza, Argentina

Abstract The syenite pegmatitic segregation veins (SPSV) of the Early Miocene La Pena alkaline complex (LPC), Mendoza, Argentina, are emplaced in a malignite body. They occur as veins, parallel layers, and small elliptical bodies 1 to 6 cm wide and 0.2 to 1 m in length. The veins with a pegmatitic to micropegmatitic texture have a thin dark border composed of andradite, potassic-hastingsite, and dark micas and a thicker internal zone of poikilitic Ba-Sr-poor K-feldspar (Or 90.3 Ab 8.9 An 0.8 ), nepheline (Ne 74.9 Ks 19.4 Qz 5.7 to Ne 78.7 Ks 20.0 Qz 1.3 ), potassic-hastingsite, dark mica, andradite, scarce clinopyroxene (diopside–hedenbergite), and locally zoned microphenocrysts of Ba-Sr-rich K-feldspar (Or 75.6 Ab 21.7 An 2.7 ). Accessory fluorapatite, titanite, interstitial sodalite, and magnetite and secondary abundant Na- and K-rich zeolites, calcite, chlorite-group minerals, and possibly cancrinite have been identified. The textural and mineralogical characteristics of the SPSV show genetic links with the host malignite that belongs to the potassic alkaline series. The SPSV were formed from a residual syenitic melt (malignite) extracted from a parental tephritic magma. In the residual malignite, the concentration of primary crystals (apatite, clinopyroxene, Ba-Sr-rich K-feldspar, and nepheline) formed a crystal network (mush) with the open spaces occupied by small amounts of residual melt enriched in Al, Na, K, and volatiles and depleted in Ba and Sr. Deformation (by shear movements plus magmatic pressures) produced microfractures and fractures which were occupied by residual interstitial melt. In situ crystallization within these fractures resulted in the formation of the SPSV.

Geochronology and tectonic settings of Late Jurassic – Early Cretaceous intrusive rocks in the Ulanhot region, central and southern Da Xingan Range

AbstractZircon U–Pb dating and whole-rock geochemical analysis have been performed on Late Jurassic – Early Cretaceous intrusive rocks of the Ulanhot area, NE China, with the aim of constraining the tectonic evolution of the central and southern Da Xingan Range. Zircon U–Pb dating indicates that Late Jurassic – Early Cretaceous magmatic events experienced four stages at:c.155 Ma;c.144 Ma; 135–130 Ma; andc.126 Ma. Thec.155 Ma magmatic event consists of quartz diorite and granite-porphyryp with the geochemical characteristic of high Sr and Sr/Y or high A/CNK (1.38), implying the primary magma was derived from partial melting of a thickened lower crust which induced the closure of the Mongol–Okhotsk Ocean. Thec.144 Ma magmatic event consists of quartz monzodiorite with the geochemical characteristics of alkaline series, and indicates the delamination of a thickened crust. The 135–130 Ma magmatic event consists of syenogranite and granite-porphyry with characteristics of both I-type and A-type granites, which induced both the subduction of the Palaeo-Pacific oceanic plate and the post-orogenic extension of the Mongol–Okhotsk Orogenic Belt. Thec.126 Ma magmatic event consisted of highly fractionated I-type biotite granite and alkaline series gabbro, marking the end of the Mongol–Okhotsk Orogen, and implying that the study area was controlled by the circum-Pacific tectonic system during this stage.

A record of post-collisional transition: evidence from geochronology and geochemistry of Palaeozoic volcanic rocks in the eastern Junggar, Central Asia

ABSTRACTAbundant clues about the post-collisional transition in the southwestern margin of the Central Asian Orogenic Belt (CAOB) have been recorded by the late Palaeozoic volcanic rocks in the eastern Junggar region. These volcanic rocks provide a better window for understanding the magmatic and tectonic transition processes. This paper reports detailed petrology, whole-rock and Sr–Nd–Pb isotope geochemistry, and in situ zircon U–Pb dating analyses of these volcanic rocks from this region. Systematic geochemical and geochronological studies show that three stages of magmatism were recorded in this area, including ca. 407 Ma and ca. 340 Ma medium-to-high-K calc-alkaline series and ca. 320 Ma alkaline and tholeiite series. The ca. 407 Ma volcanic rocks have calc-alkaline compositions, strong enrichment in large-ion lithophile elements (LILEs) and depletion in high-field strength elements (HFSEs), negative Nb anomalies, and light REE (rare earth element)-enriched patterns. The ca. 340 Ma volcanic rocks, which have similar calc-alkaline compositions and arc geochemical affinities but higher K content, have slightly lower Th/Yb and Ba/Nb values than typical island arc or continental margin volcanic suites. The compositions of the ca. 320 Ma volcanic rocks display a bimodal distribution; the ca. 320 Ma basaltic rocks are chemically similar to oceanic island basalt (OIB) but with slight depletion in Nb and Ta, wheres the acidic rocks show the features of A-type granite. The chemical compositions of these volcanic rocks indicate that the ca. 407 Ma magmatism was subduction related, while the ca. 340 Ma and ca. 320 Ma volcanic rocks were the product of post-collisional magmatism. This transition from ca. 407 Ma to ca. 320 Ma records slab subduction, slab break-off, and slab rollback and provides a plausible explanation for the complex spatial and temporal geochemical evolution of magmatism in eastern Junggar since the Devonian.

Late Pleistocene Tendürek Volcano (Eastern Anatolia, Turkey): I. Geochronology and petrographic characteristics of igneous rocks

The series of two papers presents a comprehensive isotope-geochronological and petrological-geochemical study of the Late Quaternary Tendurek Volcano (Eastern Turkey), one of the greatest volcanoes within the Caucasian—Eastern Anatolian segment of the Alpine foldbelt. The first article discusses the results of chronostratigraphic reconstruction and provides the main petrographic characteristics of the Tendurek’s igneous rocks. The K-Ar dating results show that the magmatic activity of the Tendurek Volcano developed in the Late Pleistocene time, over the period of the last 250 thousand years. Five discrete phases (I—250–200 ka, II—200–150 ka, III—150–100 ka, IV—100–70 ka, and V—<50 ka) of the youngest magmatism were identified in this study. The first two phases were represented by the fissure eruptions of alkaline basic lavas and subsequent formation of vast lava plateaus, the Caldiran and Dogubeyazit plains. In the following phases, the intermediate and moderately-acid volcanic rocks of mildly-alkaline or alkaline series started to dominate among the eruption products. According to their petrographic characteristics, the rocks of Tendurek Volcano are assigned to the alkaline association with Na-specifics (hawaiites-mugearites-benmoreites). The available geological, isotope-geochronological, and geomorphological data suggest that the Tendurek Volcano is potentially active. Nowadays, Tendurek reaches the caldera stage of its development.

New data on the composition of products of quaternary volcanism at the northwestern margin of the South China Sea shelf zone and the problem of asthenospheric diapirism

New petrological and isotope–geochemical data are obtained for rocks from the South China Sea shelf zone (Thu, Cu-Lao Re, Hong Jo islands and Katuik–Ile des Cendres island group). These data are correlated with the available published data on the volcanic rocks of the terrestrial part of Vietnam and with data on the basaltoids of the South China Sea, Thailand, and the northern part of Hainan island. Despite the fact that the studied volcanic rocks belong to different structural zones—continental margin, shelf zone, marginal sea—their formation is related to the same type of rift volcanism. Owing to this, the different compositions of the primary magmatic melts indicate, first of all, the heterogeneity of the mantle sources. The uniformity of manifestations of volcanism over the entire studied territory within the age boundaries excludes any zoning at the transition from one structure to another. The leading role of mantle diapirism in the evolution of volcanism throughout the entire Indochina region is shown. It is proposed that the formation of alkaline series and “alkaline” trends of changes in their compositions are consequences of fractionation of melts which originated from an asthenosphere plume chamber. Meanwhile, the tholeiitic magma series are of reactionary origin and “tholeiitic” trends record the processes of mixing of melts generated during melting of the lithospheric mantle with those of a plume chamber. Individual samples show insignificant contamination of melts by crustal material.

40Ar/39Ar age, lithogeochemistry and petrographic studies of the Cretaceous Alkaline Marapicu Intrusion, Rio de Janeiro, Brazil

The Marapicu Alkaline Massif is an intrusion into the Marapicu-Gericinó-Mendanha Igneous Complex that is part of the Cretaceous Poços de Caldas-Cabo Frio magmatic lineament located in the Southeastern region of Brazil. Nepheline syenites and phonolites are the most abundant rocks in the massif that also include syenites forming an alkaline series SiO2- undersatured. Chemically this series is predominantly metaluminous and to a lesser extent peralkaline. This series presents both potassic and sodic suites being the first one in greater content. The data show that both basic and intermediary rocks with parental composition sampled in this area have no genetic relationship with the other rocks of the body. Geochemistry data shows that evolution processes involved fractional crystallization with or without continental crust assimilation and also indicates that this alkaline magma was generating from an enriched mantle source. The 40Ar/39Ar age of hornblende (extracted of nepheline syenite) from Marapicu massif is 80.46 ± 0.58 Ma, which it is contrasting, with the idea of age decrease of the hotspot track from west to east on the Poços de Caldas-Cabo Frio magmatic lineament.

Late Paleoproterozoic tectonic setting of the northern margin of the North China Craton: Constraints from the geochronology and geochemistry of the mangerites in the Longhua and Jianping areas

The tectonic setting of the late Paleoproterozoic suite of anorthosite, mangerite, charnockite and alkali-feldspar granite (AMCG) on the northern margin of the North China Craton (NCC) is controversial. This paper reports on the petrology, geochronology and geochemistry of the Beibaiqi, Beipuzi and Shibalitai mangerites in the Longhua area and the Shinao mangerite in the Jianping area. Zircon U–Pb dating reveals that these mangerites formed 1768–1725Ma, similar to the other lithologies (1753–1673 Ma) of the AMCG suite on the northern margin of the NCC. The mangerites have intermediate SiO2 contents (57.2–66.8wt.%) and high K2O (4.04–7.05wt.%) and Na2O (3.75–5.50wt.%) contents, which belong to alkaline series rocks. They are enriched in light rare-earth elements (REEs) and large-ion lithophile elements (LILEs) of Rb, Ba and K, and they are depleted in heavy REEs and the high field-strength elements (HFSEs) of Th, U, Nb, Ta, Ti and P. The zircon ɛHf(t) values of these mangerites are negative (−8.3 to −1.7), with depleted mantle model ages (TDM) and average crustal two-stage modal ages (T2DM) from 2250Ma to 2533Ma and 2573Mato2959 Ma, respectively. These geochemical characteristics suggest that these mangerites originated from the early Precambrian lower crust of the NCC. Compared with the mangerites, the other lithologies of the AMCG suite display different evolutionary trends of their major elements and different distribution patterns of their REEs and trace elements, indicating that those lithologies were not formed through fractional crystallization by the same primary magma. The anorthosites share similar distribution patterns of REEs and trace elements and zircon Hf isotopic composition with associated norites. The data suggest that the anorthosites were formed by noritic magmas through fractional crystallization at the base of the lower crust. The alkali-granites and rapakivi granites display the geochemical features of A-type granites, and might have originated from partial melting of the mid-upper crust. Combined with regional geological data, these findings suggest that the AMCG suite occurred in a post-collisional/post-orogenic extensional setting rather than an anorogenic continental rift setting.

Geochronology, geochemistry, and deformation history of Late Jurassic–Early Cretaceous intrusive rocks in the Erguna Massif, NE China: Constraints on the late Mesozoic tectonic evolution of the Mongol–Okhotsk orogenic belt

This paper presents new zircon and sphene U–Pb ages, biotite and hornblende 40Ar/39Ar ages, Hf isotopic data, and geochemical data for five Mesozoic plutons in the Erguna Massif of NE China. These data are used to constrain the late Mesozoic tectonic evolution of the Mongol–Okhotsk orogenic belt. This new dating, when combined with previously published ages, indicates that the Late Jurassic–Early Cretaceous (J3–K1) intrusive rocks can be subdivided into three stages that represent periods of magmatism during the Late Jurassic (~155Ma), early Early Cretaceous (~137Ma), and late Early Cretaceous (~123Ma). In addition, the rocks have undergone later deformation recorded by peak ages of ~137 and ~123Ma. The Late Jurassic and early Early Cretaceous intrusive rocks in the study area are dominantly syenogranites and are either A-type granites or are classified as alkaline series, suggesting that they formed in an extensional environment. The late Early Cretaceous intrusive rocks in this area are generally monzogranitic and were emplaced as dikes in an extensional environment, along with coeval bimodal volcanics. These data, combined with the presence of regional unconformities in the northern part of Hebei Province and western part of Liaoning Province, and the spatial distribution of coeval volcanic rocks in NE China, suggest the Late Jurassic and early Early Cretaceous magmatisms and the early Early Cretaceous deformation in this area occurred in an extensional environment related to the delamination of a thickened part of the crust after closure of the Mongol–Okhotsk Ocean. In comparison, the late Early Cretaceous deformation and magmatism occurred in an extensional environment related to either delamination of the previously thickened crust related to the Mongol–Okhotsk tectonic regime or the subduction of the Paleo-Pacific Plate, or the combined influence of these two tectonic regimes.

Post-collisional subvolcanic rhyolites associated with the Neoproterozoic Pelotas Batholith, southern Brazil

Neoproterozoic volcanic and subvolcanic rhyolitic systems in southernmost Brazil are correlated with acid magmatism linked to different petrotectonic associations of the Sul-Rio-Grandense Shield. A portion of this volcanism in the Dom Feliciano Belt is associated with the Pelotas Batholith, which resulted from magmatic episodes associated with the Ediacaran post-collisional evolution of southern Brazil. Ana Dias Rhyolite is the main subvolcanic occurrence of this volcanism that took place in the Quitéria region, in the central part of Rio Grande do Sul State. The acid magmatism has been commonly associated with the most differentiated granite suite phases during the final stages of emplacement of the Pelotas Batholith. The Ana Dias Rhyolite is characterized as an intrusive body with rocks that present a porphyritic to seriated texture and a gradational variation to fine-grained equigranular rocks. New zircon U–Pb dating indicates crystallization age of 581.9 ± 1.9 Ma for the Ana Dias Rhyolite. Geochemistry data characterize the rhyolites as belonging to the alkaline series; they present a metaluminous to peraluminous character; elevated SiO2 and alkali concentrations, high FeOt/FeOt + MgO ratios and agpaitic index; and low Al2O3, CaO, and MgO contents. The Zr, Rb, Y, Nb, and Ga concentrations are moderate when compared with the relatively low Ba and Sr contents. These geochemistry characteristics are common in acid magmas with alkaline affinity. The behavior of certain trace elements and REE demonstrate enrichment in more incompatible elements, in addition to the negative anomaly of Ba, the slight enrichment in Ce relative to adjacent elements, as well as the enrichment in K2O and Rb relative to Nb, suggesting magmas derived from mantle sources enriched in incompatible elements with some crustal contamination. The chemical characteristics are similar to those of A-type granites associated with Neoproterozoic post-collision magmatism in the Sul-Rio-Grandense Shield.

양생방법에 따른 알칼리 및 황산염 복합자극제를 사용한 비소성 시멘트 모르타르의 특성

Entering the 20th century since the industrial revolution, the cement has been widely used in the field of construction and civil engineering due to the remarkable development of construction industry. However, result from that development, each kind of industrial by-products and waste and the carbon dioxide generated in the process of cement production cause air pollution and environmental damage so earth is getting sick now slowly. Therefore, we have to recognize importance about this. It means that the time taking specific and long-term measures have come. In this research paper, as substitution of the cement generating environmental pollution, we investigate the hydration reaction of non-Sintered Cement mortar mixed with GBFS, active stimulant of alkaline and sulphate series by using SEM and XRD, mechanical and chemical properties according to the curing method. As a result of this experiment, NSC realized outstanding strength for water curing and steam curing. It means that it has a good possibility as substitution of cement. From now on, it can be used for structure satisfying specific standard. We expect to find a substitution of outstanding cement by progressing continuous research making the best use of pros and cons according to the curing method.

Geochemistry of the alkaline volcanicsubvolcanic rocks of the Fernando de Noronha Archipelago, southern Atlantic Ocean

&lt;p&gt;The Fernando de Noronha Archipelago presents, on its main island, a centrally-located stratigraphic unit, the Remédios Formation (age around 8 - 12 Ma) constituted by basal pyroclastic rocks intruded by dikes, plugs and domes of varied igneous rocks, capped by flows and pyroclastics of mafic to ultramafic rocks of the Quixaba Formation (age around 1 - 3 Ma), which is limited from the underlying unit by an extensive irregular erosion surface. A predominant sodic Remédios series (basanites, tephrites, tephriphonolites, essexite, phonolites) can be separated from a moderately potassic Remédios sequence (alkali basalts, trachyandesites, trachytes), both alkaline series showing mostly continuous geochemical trends in variation diagrams for major as well as trace elements, indicating evolution by crystal fractionation (mainly, separation of mafic minerals, including apatites and titanites). There are textural and mineralogical evidences pointing to hybrid origin of some intermediate rocks (e.g., resorbed pyroxene phenocrysts in basaltic trachyandesites, and in some lamprophyres). The primitive Quixaba rocks are mostly melanephelinites and basanites, primitive undersaturated sodic types. Geology (erosion surface), stratigraphy (two distinct units separated by a large time interval), petrography (varied Remédios Formation, more uniform Quixaba unit) and geochemistry indicate that the islands represent the activity of a protracted volcanic episode, fueled by intermittent melting of an enriched mantle, not related to asthenospheric plume activity.&lt;/p&gt;

The volcanic-subvolcanic rocks of the fernando de noronha archipelago, southern atlantic ocean: Mineral chemistry

Abstract Fernando de Noronha archipelago presents an older Remédios Formation with subvolcanic intrusions, belonging to two different alkaline series, the sodic (undersaturated: basanites, tephrites, essexites, tephriphonolites, phonolites), and potassic ones (mildly undersaturated to silicic, with alkali basalts, basaltic trachyandesites, trachyandesites, trachytes), and lamprophyres. The upper Quixaba Formation presents nephelinite flows and basanites. A third minor unit, São José, is constituted by basanites carrying mantle xenoliths. Magnesian olivines occur in the Remédios basanites and alkali basalts, and in nephelinites. Melilites are present as groundmass grains in melilite melanephelinites (MEM). Clinopyroxenes (cpx) are mostly salites to titaniferous salites (Remédios sodic series), grading into aegirines in the differentiated aphyric phonolites. Cpx in the lamprophyres show disequilibrium textures. In the Quixaba flows, cpx are salites, enriched in Mg (especially in MEM). Amphiboles, remarkably, are common in tephriphonolites and phonolites and in basaltic trachyandesites, sometimes with disequilibrum zoning textures, and a conspicuous phase in lamprophyres. Dark micas are present as groundmass plates in MEM, OLM and PYM (olivine and pyroxene melanephelinites), with compositional variety (enriched in Ti, Ba, Sr) depending on the composition of the parent rock; BaO can be as high as 16–19%. Feldspars crystallize as calcic plagioclases, sanidines and anorthoclases, depending on the rock types, as phenocrysts and in groundmass, both in Quixaba and Remédios rocks; they are absent in nephelinites. Nephelines are found in Remédios sodic series types and Quixaba rocks. Haüyne and noseane are rarely observed in Remédios rocks.

Conditions of accumulation of radioactive metals in the process of differentiation of ultrabasic alkaline-carbonatite rock associations

The distribution of radioactive elements in alkaline rocks from Polar Siberia and Ukraine shows that U and Th are markedly concentrated in carbonatite complex and nepheline syenite as final products of magma fractionation. Peralkaline nepheline syenites from Polar Siberia are characterized by very high contents of radioactive elements, which are close to the economic level. Radioactive elements are also concentrated in rocks of the carbonatite complex. For example, some soevites contain up to 294 × 10−4%U and 916 × 10−4% Th. In late dolomite carbonatites, the contents of radioactive elements are appreciably lower. The Th/U ratio in alkaline rocks of Polar Siberia is close to the chondrite value in primary high-Mg rocks and increases in late derivatives: phoscorite, calcite and dolomite carbonatites. The main amount of radioactive elements is contained in rare-metal accessory minerals: perovskite, pyrochlore, calzirtite, and apatite. Rock-forming minerals are distinguished by very low concentrations of radioactive elements. In alkaline series of the Chernigovka massif (Ukraine), U and Th also accumulate in the course of crystal fractionation, especially in phoscorites from the carbonatite complex. Mantle xenoliths and alkaline rocks from Ukraine reveal uranium specialization. Most likely, the discrepancy in fractionation of radioactive elements between Polar Siberia and Ukraine is caused by different geodynamic regimes of these provinces. The Mesozoic alkaline magmatism of Polar Siberia is a part of the Siberian superplume, whereas the Proterozoic alkaline complex in Ukraine is related to subduction of the oceanic crust.

남한에서 주상절리의 분포와 암석학적 특성

남한에서의 주상절리 분포지역과 그들의 형태학적, 암석학적 특징을 연구하였다. 현재까지 보고된 남한의 주상절리 분포지역은 최소한 68개 지역이다. 이들은 지리적 여건과 화산활동에 따라 5개의 그룹으로 나눌 수 있다. 1) 한탄강유역에는 16개 지역에 주상절리가 발달하는데, 15개 지역은 제4기의 현무암질 용암이며, 나머지 1지역은 백악기 화산암이다. 2) 제주도의 주상절리는 18개 지역이다. 이들 모두 신생대 제4기에 분출하였으며, 대부분은 현무암질 용암이고, 산방산과 백록담 등은 조면암이다. 제주도 주상절리는 칼러네이드와 엔태블러춰가 잘 발달하며, 끌자국도 선명하게 관찰된다. 3) 울릉도와 독도에서는 국수바위를 비롯한 5개 지역에서 관찰되며, 이들은 제4기 조면암이다. 4) 포항-경주-울산의 8개 지역에서 돔형, 방사상, 수평 및 수직 주상절리가 발달하는데, 이들 모두는 제3기 화산암이다. 충청남도 평택-아산지역, 그리고 강원도 고성의 제3기 현무암에서 주상절리가 관찰된다. 5) 남해안과 서해안에는 모두 15개 지역에서 주상절리가 관찰되는데, 이들은 백악기에 분출한 화산암으로 현무암에서 유문암까지, 용암에서 용결응회암까지 다양한 암석으로 구성되어 있다. 무등산과 주왕산의 주상절리도 백악기에 분출한 용결응회암이다. 남한의 주상절리를 지역별로 분류하면, 강원도가 5개, 경기도 13개, 충남 2개, 경북 14개, 전북 1개, 전남 10개, 경남 5개, 제주 18개 지역이다. 주상절리의 형성 시기는 중생대 백악기가 18개, 신생대 제3기가 12개, 그리고 신생대 제4기가 38개 지역이다. 화산암의 마그마계열은 알칼리암계열이 36개, 비알칼리암계열이 32개 지역이다. This study has been designed to collate distribution, morphology, petrology of columnar joint in South Korea. Reported columnar joint areas in South Korea are 68, until the present time. These can be divided into five group by geography and volcanic activity. 1) The 16 columnar joint areas are distributed in Hantangang region. The 15 areas in this region are composed of basaltic lava in the Quaternary period, and the other 1 area is composed of volcanic rocks in the Cretaceous period. 2) The 18 columnar joint areas are distributed in Jeju island. Most of them are composed of basaltic lava(alkali basalt and Hawaiite), and the Sanbangsan and Baegrokdam area are composed of trachyte in the Quaternary period. Colonnade, entablature and chisel mark of the columnar joint are typically occur in basaltic lava. 3) The 5 columnar joint areas are distributed into the Ulleung island and Dokdo including Guksubawi. These are consisted of relatively well-formed trachyte columns in the Quaternary period. 4) The 8 columnar joint areas are distributed into the Pohang, Gyeongju and Ulsan region and consist of the Tertiary period volcanic rock. It's shape are dome, radial, horizontal and vertical. The 4 columnar joint areas are reported in the Pyeongtaek and Asan city of Chungcheongnamdo and Gosung of Gangwondo. All of them are the Tertiary period basalt. 5) The 15 columnar joint areas are distributed into the west and south coast region. Those are consisted of various rock type(from basalt to dacite), various occurrences(lava flow to welded tuff), and various diameters(20 cm to several meters). The columnar joint of Mudeung mountain and Juwang mountain are welded tuff in the Cretaceous period. The columnar joint is distributed over a wide area in South Korea, 5 in Gangwondo, 13 in Gyeonggido, 2 in Chungnam, 14 in Gyeongbuk, 1 in Jeonbuk, 10 in Jeonnam, 5 in Gyeongnam, and 18 in Jeju. The columnar joints in South Korea can be arranged in order of formative period, 18 in the Cretaceous period, 12 in the Tertiary period, and 38 in the Quaternary period. By magma series, 36 are belong to alkaline series and 32 are belong to sub-alkaline series.

Petrology of Quaternary volcanic rocks and related plutonic xenoliths from Gölcük volcano, Isparta Angle, Turkey: Origin and evolution of the high-K alkaline series

The Quaternary volcanism of Isparta, south-western Anatolia, belongs to the post-collisional alkali-potassic to ultrapotassic magmatism, active since Miocene, from Afyon to Isparta. In the so-called Isparta Angle, the magmatism is contemporaneous with the Aegean extensional regime initiated during the Late Miocene and active throughout the Pliocene and Quaternary. The Gölcük volcano-forming stages consist of three main eruptive cycles: Cycle I comprising 200m-thick pyroclastic flow deposits; Cycle II consisting of tephriphonolitic lava dome-flows extruded throughout the caldera; and Cycle III characterized by tuff-ring deposits related to the last phreatoplinian events. These late explosive events sampled plutonic xenoliths that allow to better constrain magma fractionation processes that operated at depth in the magma chamber. Magma evolution was first controlled by accumulation of clinopyroxene, phlogopite and apatite, then by phlogopite, amphibole and feldspars, with apatite, magnetite, titanite and zircon as accessories. Crystallization of clinopyroxene, phlogopite and amphibole probably controlled the silica-saturation trend of the whole series and faithfully reflect intensive H2O variations in the magma that were responsible of explosive cyclic events. The parental magma may have had a lamprophyric-tephritic composition. Trace element and isotope ratios indicate a prevalent asthenospheric source versus lithospheric one. Geochemical features, such as strong enrichment of LILE, REE, HFSE in the Gölcük magma point to the involvement of a asthenospheric OIB-type melt with a possible carbonatitic component, that interacted with remnants of the delaminated lithosphere during upwelling.

Early Permian–Late Triassic Magmatism in the Tuotuohe Region of the Qinghai–Tibet Plateau: Constraints on the Tectonic evolution of the Western Segment of the Jinshajiang Suture

Abstract:In this paper we present new zircon U–Pb ages, whole‐rock major and trace element analyses, and zircon Hf isotopic data for magmatic rocks in the Tuotuohe region of the western segment of the Jinshajiang suture. Our aim is to constrain the Early Permian–Late Triassic tectonic evolution of the region. Zircons from the magmatic rocks of the Tuotuohe region are euhedral–subhedral in shape and display fine‐scale oscillatory zoning as well as high Th/U ratios (0.4–4.6), indicating a magmatic origin. The zircon U–Pb ages obtained using LA–ICP–MS are 281 ± 1 Ma, 258 ± 1 Ma, 244 ± 1 Ma, and 216 ± 1 Ma, which indicate magmatism in the Early Permian–Late Triassic. A diorite from Bashihubei (BSHN) has SiO2= 57.18–59.97 wt%, A12O3= 15.70–16.53 wt%, and total alkalis (Na2O + K2O) = 4.46–6.34 wt%, typical of calc‐alkaline and metaluminous series. A gabbro from Bashibadaoban (BSBDB) belongs to the alkaline series, and is poor in SiO2 (45.46–54.03 wt%) but rich in A12O3 (16.19–17.39 wt%) and total alkalis (Na2O + K2O = 5.48–6.26 wt%). The BSHN diorite and the BSBDB gabbro both display an enrichment of LREEs and LILEs and depletion of HFSEs, and they have no obvious Eu anomaly; they have relatively low MgO contents (2.54–4.93 wt%), Mgs# values of 43 to 52, and low Cr and Ni contents (8.07–33.6 ppm and 4.41–14.2 ppm, respectively), indicating they differentiated from primitive mantle magmas. They have low Nb/U, Ta/U, and Ce/Pb ratios (1.3–9.6, 0.2–0.8, and 0.1–18.1, respectively), and their initial Hf isotopic ratios range from +9.6 to +16.9 (BSHN diorite) and +6.5 to +12.6 (BSBDB gabbro), suggesting their primary magmas were derived mainly from the partial melting of a mantle wedge that had been metasomatized by subduction fluids. Taking all the new data together, we conclude that the western and eastern segment of the Jinshajiang suture regions underwent identical processes of evolution in the Early Permian–Late Triassic: oceanic crust subduction before the Early Permian, continental collision during the Early–Middle Triassic, and post‐collisional extension from the Late Triassic.

Magma source and evolution law in Yueshan ore field, Anhui Province, China

Major elements, trace elements and sulfur, oxygen isotopic compositions of the main intrusions were studied in Yueshan area. The fact that intrusions enriched in Th and Sr, and depleted in Rb and Ba in this area, suggests that the original magma roots in alkali basalt magma of upper mantle, with deep characteristics. It can be seen that the diagenesis environments are the island arc and active continental margin areas from the lg τ to lg σ diagram of intrusions. With the increase of SiO2, Fe2O3, MnO and P2O5 decrease, which shows that the magma of Yueshan area endured crystal fractionation of ferromanganese mineral and apatite in early evolution stage. With the further rise and evolution of magma, magma composition of calcium increased, meanwhile enriched in Zr, and depleted in Nb and Ta. This indicates that crustal component is gradually added, the assimilation and contamination occur between magma and crustal material, which includes the magma evolving, from calc-alkaline series to alkaline series. The results show that crystal fractionation, assimilation and contamination are the main evolution law of magma in this area.