首页 | 学报简介 | 编委会 | 投稿指南 | 订阅指南 | 文件下载 | 期刊浏览 | 关键词检索 | 高级检索 | 联系我们   

注释: Web of Science™ ============================================================

FN Thomson Reuters Web of Science™
VR 1.0
 

PT J
AU Li, YJ
Wu, L
Li, SL
Li, GY
Shen, R
Li, Z
Wang, ZP
Wang, ZY
AF LI YongJun
Wu Le
Li ShuLing
Li GanYu
Shen Rui
Li Zhao
Wang ZuoPeng
Wang ZhenYu
TI Tectonic evolution of Yining Block: Insights from Carboniferous volcanic rocks
SO ACTA PETROLOGICA SINICA
AB Although the Yining Block has long been focused on, specifics of the evolution and configuration during Carboniferous are still debated. There are three main controversial views. First one focuses on whether or not the Tianshan oceanic basin existed in Carboniferous. Second one is, if the oceanic basin existed, when closed it is. Meanwhile, the third topic is about the polarity of subduction. Therefore, these significant geologic issues focus on volcanic rocks. Carboniferous volcanic rocks are widespread in Yining Block; this association plays a key role for tectonic evolution, with acute controversies for a long time. This study showed that calcalkaline volcano-sedimentary rocks were developed during Early Carboniferous in fore-arc-inter-arc-back-arc basin system in Yining Block from Tarim plate. By contrast, Late Carboniferous bimodal volcanic rocks and sedimentary association formed within regional extension tectonic setting and show affinity with continental rift, a responsible for intra-continental geological processes after the assembling of the Junggar and Tarim blocks. These observations suggest that the ancient oceanic basin should be close in late Early Carboniferous. The temporal-spatial distribution, which of the Early Carboniferous volcanic-sedimentary rock association, suggest that Tianshan ancient oceanic basin in Early Carboniferous is similar with the mordent typical trench-arc-basin system from Japan. Moreover, Carboniferous volcanic rocks provide the momentous information to restrict tectonic evolution in Yining Block.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 1
EP 15
UT WOS:000393257900001
ER  

PT J
AU Li, GY
Li, YJ
Wang, R
Yang, GX
Xiang, KP
Liu, J
Tong, LL
AF Li GanYu
Li YongJun
Wang Ran
Yang GaoXue
Xiang KunPeng
Liu Jia
Tong LiLi
TI The discovery and significance of Late Carboniferous sanukitoids in Hala' alate Mountain, West Junggar
SO ACTA PETROLOGICA SINICA
AB The Late Carboniferous volcanic rocks consist of basaltic andesite and pyroxene andesite which are widespread in Hala' alate Mountain, West Junggar. The volcanic rocks belong to talc-alkaline series and show a remarkable geochemical affinity with Cenozoic sanukitoids of the Setouchi Volcanic Belt of SW Japan with high SiO2 (52.88%similar to 56. 89%), MgO (3. 47%similar to 6. 88%, MG(#) ranging from 48.5 to 63.7), Sr (442 x 10(-6) similar to 970 x 10(-6)), Ba (199 x 10(-6) similar to 796 x 10(-6) K/Na ranging from 0.22 to 0.70, P2O5 changing with a wide range (0. 18%similar to 0. 52%). Moreover, all samples are enriched in large-ion lithophile elements and light rare earth elements ((La/Yb)(N) =1. 88 similar to 15. 9), but strongly depleted in some high field strength elements (e. g. Nb, Ta and Hf) and heavy rare earth elements with slight negative Eu anomalies (delta Eu = 0.77 similar to 0. 94). Additionally, the volcanic rocks have the same characteristics of Sr-Nd-Pb isotopes as typical sanukitoids (((87) Sr/(86) Sr) = 0. 70366 similar to 0. 70409, ((143) Nd/(144) Nd)(i) = 0.51247 similar to 0.512564, epsilon(Nd) (t) = 4.41 similar to 6. 19, (206) Pb/Pb-204 = 18. 220 similar to 18.405, Pb-207/Pb-204 = 15. 482 similar to 15. 522, Pb-208/(204) Pb = 37.991 similar to 38. 296). The confirmation of sanukitoids in Hala' alate Mountain proofs that it provides a new idea for studying the evolution of West Junggar, and provides important constraints on the remnant ocean basin closed time of West Junggar, meanwhile it indicate that the closed time should be postponed to the end of Late Carboniferous instead of the Early Carboniferous.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 16
EP 30
UT WOS:000393257900002
ER  

PT J
AU Liu, JQ
Chen, LH
Zhong, Y
Lim, WH
Wang, XJ
AF Liu JianQiang
Chen LiHui
Zhong Yuan
Lim WeyHern
Wang XiaoJun
TI Petrological, K-Ar chronological and volcanic geological characteristics of Quaternary Xunke high-Mg# andesites from the Lesser Khingan Range
SO ACTA PETROLOGICA SINICA
AB The Quaternary Xunke volcanic rocks are located in the northern Lesser Khingan Range, Heilongjiang Province, covering an area of about 3000km(2). These volcanic rocks are mainly basaltic andesites and basaltic trachyandesites, with minor trachyandesites and andesites. They have high SiO2 contents (54. 3%similar to 57. 4 %) and Mg# (49. 6 similar to 57. 8) and medium MgO contents (3. 82%similar to 5. 80%), falling into the scope of high-Mg# andesites (HMAs). Based on the distribution of craters and higher terrain of the southern part of Xunke volcanic field, we speculate that the rocks in the northern part were formed by magma flows from the south. Based on their K-Ar dating (1. 12 similar to 0. 25Ma), the Xunke high-Mg# andesites can be subdivided into two periods; the Early Pleistocene (1. 12 similar to 1. 00Ma) and the Middle Pleistocene (0. 68 similar to 0. 25Ma). Thin layer of volcanic ash was found between these Quaternary lavas and fluviatile-lacustrine facies sediments, which indicates that small-scale magmatic explosion happened before abundant flood lavas formed.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 31
EP 40
UT WOS:000393257900003
ER  

PT J
AU Hong, LB
Zhang, YH
Ren, ZY
Xu, YG
Yan, W
AF Hong LuBing
Zhang YinHui
Ren ZhongYuan
Xu YiGang
Yan Wen
TI Petrogenesis of Huangbanjigou high magensiun andesite in Early Cretaceous Yixian Formation, western Liaoning
SO ACTA PETROLOGICA SINICA
AB Olivine-hosted melt inclusions and their hosts, together with the bulk rocks were used to investigate the petrogenesis of the Huangbanjigou volcanic rocks in the Early Cretaceous Yixian Formation, western Liaoning Province. The Huangbanjigou volcanic rocks show the features of high magnesium andesite, such as SiO2 = 53. 41% similar to 53.74%, MgO = 8. 15%similar to 8.23%, Mg-# = 70 (Mg-# = mol Mg/(Mg + Fe2+)). They are sub-alkaline series, plating in the field of basaltic andesite in the TAS diagram. They also exhibit the characteristics of the mantle attributions, such as moderately high Ni (119 x 10(-6) similar to 125 x 10(-6)) and high Cr (467 x 10(-6) similar to 521 x 10(-6)). The Huangbanjigou high magnesium andesites have 920 x 10(-6) similar to 930 x 10(-6) Sr, 16. 1 x 10(-6) similar to 16. 4 x 10(-6) Y and 57 similar to 58 Sr/Y. In the mantle primitive-normalized spider diagram, the Huangbanjigou high magnesium andesites show fractionation from light to heavy rare earth elements, significant and slight negative anomalies of Nb-Ta-Ti and Zr-Hf,, respectively, and positive anomalies of BaSr-Pb; all these features resemble that of the continental lower crust. The olivine-hosted melt inclusions have 6. 5% similar to 9. 7% MgO and 51% 53% SiO2, unlike those of the typical high magnesium andesite. They are alkaline series, falling in the field of basaltic trachyandesite in the TAS plot. There are significant or slight negative relationships between MgO and other major element oxides, pointing to the olivine-controlled fractionation. Olivine crystals of the Huangbanjigou high magnesium andesites have Fo = 75 similar to 91, CaO = 0. 10%similar to 0. 18%, NiO = 0. 05%similar to 0. 41%, Fe/Mn = 60 similar to 80. There are large compositional discrepancies between the bulk rocks and the melt inclusions of the Huangbanjigou high magnesium andesites, such as the melt inclusions with higher Al2O3 and lower SiO2. Together with their similar trace element features to those of the continental lower crust, we suggest that the Huangbanjigou high magnesium andesites is the product of the crust-mantle interaction; they must assimilate an acid silicate melt from the lower crust during their magma evolution in the crust depth. We suggest that the mantle-derived melts of the Huangbanjigou andesites are the partial melts of the orthopyroxene-rich pyroxenite, on the basis of (1) relatively low Ni but high Me of the bulk rocks; (2) low CaO of the melt inclusions; (3) melt inclusion plotting in the SiO2-enriched side of the thermal divide boundary in the phase diagram of the CATS Olivine -Quartz; and (4) the olivine crystals with low Ca and steeper relationship between Fo and Ni. We argue that the widespread high magnesium andesites in the Early Cretaceous Yixian Formation, western Liaoning Province, likely underwent crust-mantle interaction; hence, they can not be considered as an important evidence of the delamination process resulting in the large scale thinning of the lithosphere.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 41
EP 55
UT WOS:000393257900004
ER  

PT J
AU Yh, HM
Zhao, B
Xu, JD
Wei, FX
AF Yh HongMei
Zhao Bo
Xu JianDong
Wei FeiXiang
TI Magmatic processes of Daheishan volcano, Ashikule volcano cluster in the western Kunlun Mountains, China
SO ACTA PETROLOGICA SINICA
AB Western Kunlun Ashikule volcano cluster (AVC) is located in the northwestern edge of Qinghai-Tibet Plateau. Because of the severe natural environment, few researches have been done. Daheishan volcano has the widest lava area, and is the largest volcano in this area. The petrographic texture, phenocryst type and chemical composition of the volcanic rocks in Daheishan volcano were analyzed in detail, and their implication in magmatic process was discussed. The whole rock composition of Daheishan volcano has a large range, from basaltic trachyandensite, trachyandensite to trachyte, and the Harker diagrams show some linear relationships, which indicate the existence of magmatic evolution relationship between the three types of magma. Phenocrysts in Daheishan volcanic rocks are mainly pyroxene and plagioclase, most of which have characteristics of corrosion, reverse zoning and reaction boundary structure, indicating magma mixing. The results estimated by using thermobarometers show that the equilibrium temperatures of basaltic trachyandensite and trachyandensite are 1124 similar to 1176 degrees C, and the equilibrium pressures are 0. 55 similar to 0. 81GPa, corresponding to the depth of about 16. 5 similar to 24. 3km. The equilibrium temperatures and pressures are 1059 similar to 1071 degrees C and 0. 39 similar to 0. 39GPa for trachyte, corresponding to the depth of 11. 8 similar to 17. 7km. Research shows that the primary magma under Daheishan volcano experienced an evolution from basaltic trachyandensite, trachyandensite to trachyte, and three types of magma characterized by layering may exist in the magma chamber at the same time, occurring magma mixing, and even mixing with the surrounding acidic magma.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 56
EP 68
UT WOS:000393257900005
ER  

PT J
AU Hu, SL
Luo, D
Chen, LH
AF Hu SenLin
Luo Dan
Chen LiHui
TI Genesis of sieve-textured rim of spinel in mantle xenoliths
SO ACTA PETROLOGICA SINICA
AB Black reaction rims are observed in spinel of mantle peridotite xenoliths hosted in alkali basalts from Dashan and Fangshan, Shandong Province. According to their back-scattered images, these reaction rims can be subdivided into homogeneous rims and sieve-textured rims. Two kinds of rim can be observed in a single spinel mineral, too. Homogeneous rims are usually developed in spinel xenocrysts and spinels in peridotite xenoliths, which are directly in contact with host rocks. In contrast, spinels with sieve textured rim do not direct contact with host, although they are still distributed in the edge of peridotite xenoliths. The sieve-textured rim is characterized with many porosity and compositions of Cr-rich spinel or chromite. The sieve-textured spinel has much higher Cr2O3 content (23. 42% to 65. 96%), Cr-# (78. 97 to 92. 49) and lower Mg-# (17. 22 to 43. 02) than its unreacted core. Furthermore, the sieve-textured spinel has a bit ligher TiO2 and MnO than the core. There are some glasses in direct contact with the sieve-textured rim, which is characterized with high Al2O3(8. 00%similar to 17. 57%) and MgO (17. 89%similar to 26. 02%) contents. The homogeneous rim has no porosity but fracture, and has higher TiO2 and FeOT contents. Moreover, the outermost of rim is titanomagnetite. The homogeneous rim also shows compositional zoning with decrease of TiO2, FeOT and increase of Al2O Cr2O3 and MgO contents from the outer part to the inner part of the rims. The spatial link between the two kinds of rim for spinel and the host rocks suggests that host magmas play an important role in the formation of such rims. Although the sieve-textured spinel has higher Cr-# than unreacted core, the lower Me and a slight higher TiO2 and MnO do not support a genesis of partial melting for such rims. Here we propose that these two kinds of rim are products of different stages of interactions between spinel and host magmas. When peridotite xenoliths were trapped by host magmas, the disequilibrium between peridotite and host magmas causes dissolution reaction. Cr is the most stable element in spinel, Al and Mg are opposite. At the initial stage, Al and Mg are dissolved into host magmas first and sieve-textured rims are developed in spinel with higher Cr-# and lower Me values. Moreover, Ti and Mn from host magmas are exchanged into sieve-textured spinel. Metal oxides are firstly saturated and crystalized from the mixed melt which generated by diffusive mixing between dissolved spinel and host magmas. As the reaction proceeds, earlier crystalline minerals grow, coarsen and close the holes, resulting in homogeneous rim finally. Diffusive mixing between melts and minerals crystallization causes variable melt composition at interaction interface, this is the reason of homogeneous rims showing compositional zoning. Since the host magmas infiltrated into the interior of peridotite xenolith is limited, the interaction between magmas and spinel is still at the initial stage, and only sieve-textured rims are developed in these spinel crystals. On the contrary, spinels in direct contact with host magmas show homogeneous rims due to strongly interactions with sufficient reacting magmas.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 69
EP 80
UT WOS:000393257900006
ER  

PT J
AU Gao, JL
Liu, JQ
Guo, ZF
Meng, FC
Zhai, LN
Li, ZP
AF Gao JinLiang
Liu JiaQi
Guo ZhengFu
Meng FanChao
Zhai LiNa
Li ZhongPing
TI Chemical and carbon isotopic compositions of volatiles in Shuangliao Cenozoic basalts and related mantle xenoliths: Implications for origins of volatiles
SO ACTA PETROLOGICA SINICA
AB The mantle fluids hosted in basalts and mantle xenoliths are important for us to understand characteristics of magmatic source and evolution of lithospheric mantle. We have investigated the features of volatiles extracted from basaltic rocks and related xenoliths collected from Shuangliao volcanic field in order to reveal the characteristics and geneses of mantle fluids. Two types of fluid inclusions can be recognized in olivine phenocrysts of Shuangliao basalts and constituent minerals of xenoliths: the early stage and late stage fluid inclusions. The volatiles in early stage of inclusions were trapped during crystallization of minerals and represent the primary volatiles of magmas. The volatiles in late stage of inclusions were trapped by minerals during alteration and metasomatism processes and represent the secondary volatiles. The volatiles in early and late stage of inclusions were released at high temperature interval (600 similar to 1200 degrees C) and low temperature interval (200 similar to 600 degrees C), respectively. Primary volatiles of xenoliths are composed mainly of H2O, CO and H-2 with minor CO2 and CH4. Metasomatic volatiles of xenoliths and primary volatiles in olivine phenocrysts are dominated by H2O and CO2 with minor CO, H-2 and CH4. The primary and metasomatic volatiles in mantle xenoliths and primary volatiles in olivine phenocrysts all contain biogenic CO2 and hydrocarbons. It indicates that biogenic volatiles from organic matters were introduced into lithospheric mantle and magma source of Shuangliao basalts. The biogenic volatiles in magma source of Shuangliao basalts and metasomatic fluids in lithospheric mantle were most likely derived from the sedimentary organic matters in the subducted Pacific slab. The plagioclase phenocrysts and matrix of Shuangliao basalts contain much more volatiles than minerals mentioned above. The volatiles are composed mainly of CO2 and H2O. The delta C-13 values of CO2 are much lower than that extracted from olivine phenocrysts, which can be interpreted as a result of degassing during ascent of magma.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 81
EP 92
UT WOS:000393257900007
ER  

PT J
AU Zhang, MJ
Yu, M
Tang, QY
Yang, Y
Chen, ST
Li, ZP
Shi, JA
AF Zhang MingJie
Yu Ming
Tang QingYan
Yang Yang
Chen SiTong
Li ZhongPing
Shi JiAn
TI The volatile conditions of Permian basaltic magmatism in northwestern Junggar basin of Xinjiang, China: Constraints from chemical and carbon isotopic compositions of volatiles in basalts
SO ACTA PETROLOGICA SINICA
AB The Carboniferous-Permian basalts are occurred in deep part of northwestern Junggar basin, Xinjiang, China. The volatile conditions of the Permian basaltic magmatism had not been studied. The chemical and carbon isotopic compositions of volatiles in the matrix of Permian basalt cores were measured by stepwise heating mass spectrometer. The results showed that the volatiles in Permian basalts from northwestern Junggar basin were composed of dominated H2O with an average of 13789mm(3). STP/g (STP-standard tempeture and pressure), with minor CO2, O-2, H2S and N-2. The delta C-13 values of CO2 (-28. 9 parts per thousand to -15. 8 parts per thousand) and delta C-13(cH4) (-36. 8 parts per thousand similar to -21. 9 parts per thousand) were plotted in the delta C-13 ranges of crust and methane oxidation. The CH4, C2H6, C3H8, and C4H10 etc. methane homologues showed the normal distribution pattern of carbon isotopic compositions among CH4 to C4H10, which are the carbon isotopic features of thermogenic hydrocarbon gases of organic materials in oceanic sedimentary. The delta C-13 values of CH4 released at 400 similar to 800 degrees C (about -25 parts per thousand) are heavier than those at 200 similar to 400 degrees C (about 35 parts per thousand), and some samples showed partial reversal pattern in CH, to C3H, released at 400 similar to 800 degrees C, suggested that volatiles originated from mantle could be mixed by hydrocarbons from thermally cracked by sedimentary organic materials, which should be volatiles degassed from alterated subducted oceanic sedimentary. Large quatity of H2O indicated the addition of recycled volatiles in arc. The chemical and carbon isotopic compositions of CO2 and CH4 reveal long time alteration of organic materials, and imply long time uplifting after basaltic magmatism.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 93
EP 103
UT WOS:000393257900008
ER  

PT J
AU Tang, QY
Li, JP
Zhang, MJ
Song, Z
Dang, YX
Du, L
AF Tang QingYan
Li JianPing
Zhang MingJei
Song Zhe
Dang YongXi
Du Li
TI The volatile conditions of ore-forming magma for the Xiarihamu Ni-Cu sulfide deposit in East Kunlun orogenic belt, western China: Constraints from chemical and carbon isotopic compositions of volatiles
SO ACTA PETROLOGICA SINICA
AB The newly-discovered Xiarihamu magmatic Ni-Cu sulfide deposit in the East Kunlun orogenic belt, China is the largest one ever found in arc settings. In this study, the chemical and carbon isotopic compositions of volatiles in pyroxene crystals of different types of rocks from the Early Devonian Xiarihamu mafic-ultramafic intrusion were measured with a stepwise heating mass spectrometer. The results showed the total volatiles released from mineral separates in Xiarihamu deposit have relatively low contents with an average of 888mm(3). STP/g (STP-standard temperature and pressure). The volatiles were dominated by H2O (48mol%), with minor H-2 (26%), CO2 (15%) and CO (5%). The H2S contents gradually increased from lherzolite (10mm(3)/g), olivine websterite (18mm(3)/ g) to websterite (28mm(3)/g), indicating that some sulfur-bearing components has been added into the magma during its evolution. The delta C-13 values of CO, ranging from-23. 5 parts per thousand to- 5. 0 parts per thousand were plotted in the area between crust and mantle. The delta(13)Cvalues of CH4, C2H6, C3H6 and C4H10 etc. methane homologues showed the normal distribution pattern of carbon isotopic composition among CH4 to C4H10 in most of the samples, and partial reversal distribution pattern in some samples, which were attributed to the thermogenic hydrocarbon gases by oceanic organic materials. The rather low H2O and high H-2 contents in Xiarihamu mafic-ultramafic rocks indicated that the magma was formed in a reduced volatile condition, and the oceanic sedimentary rock could be subducted into the mantle. Country rock contamination and the addition of S-rich fluid to the magma chamber may be the main mechanism for sulfide saturation in Xiarihamu magmatic Ni-Cu sulfide deposit.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 104
EP 114
UT WOS:000393257900009
ER  

PT J
AU Liu, L
Xu, XS
Xia, Y
Liang, QD
Pei, XL
AF Liu Lei
Xu XiSheng
Xia Yan
Liang QiongDan
Pei XiaoLi
TI Disintegration of Late Mesozoic Zhucun Formation in southeastern Zhejiang: Geochronology and petrogenesis of the related volcanic rocks
SO ACTA PETROLOGICA SINICA
AB The once designated Zhucun Formation in Xiaoxiong basin is investigated to be geochronologically earlier (128Ma) not only than the overlying upper volcanic series (110 similar to 88Ma), but also than the underlying Jiuliping Formation (122 similar to 120Ma), but coeval to the Xishantou Formation (130 similar to 128Ma). Zircon Hf isotopic compositions of the studied Zhucun Formation rhyolitic tuff show enriched characteristics with Paleoproterozoic crustal model ages (epsilon(Hf)(t) =-16.4 similar to-13. 6, t(DM2) = 2. 01 similar to 2. 09Ga), also similar to the Lower Moshishan Group, such as the Xishantou Formation. Note these and the pyroclastic-rhyolitic volcanic rock assemblages and other regional geological features, the foundation basis of the Zhucun Formation is considered to be insufficient, and the Formation should be disintegrated. On the other hand, the enriched zircon Hf isotopic compositions of the studied Zhucun Formation rhyolitic tuff show that it was derived mainly from partial melting of the Paleoproterozoic crustal basement, further indicating that the Lower Moshishan Group volcanic rocks inland were derived with depleted-mantle derived material contribution, which was barely noticed in previous studies. The increased depleted-mantle derived material contribution in the volcanic petrogenesis and the pyroclastic-rhyolitic-bimodal volcanic assemblages both imply increased lithospheric extension, plausibly caused by rollback of the subducted paleo-Pacific slab.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 115
EP 126
UT WOS:000393257900010
ER  

PT J
AU Zhao, YW
Fan, QC
Li, N
Gong, LW
AF Zhao YongWei
Fan QiCheng
Li Ni
Gong LiWen
TI Study on volcanic geology characteristics and magma feeding fractures of Late Quaternary volcanoes in Dalinor volcanic field, Inner Mongolia
SO ACTA PETROLOGICA SINICA
AB Dalinor volcanic field is located in the middle of the Central Asia Orogen Belt, and on the west of middle part of Greater Hinggan Mt. -Taihang Mt. Gravity Lineament. It is composed of more than one hundred volcanoes, which erupted since Pliocene to Holocene period. This study focused on the magma feeding fractures of Late Quaternary volcanoes based on two lines of evidence: crater elongation and cone alignments. The data revealed NE and NEE were two preferred azimuths for these feeding fractures, consistent with the azimuth of regional maximum principal stress. It is inferred that a NEE trending sinistral transpressional stress field worked on the study area. The resulting Reidel fractures and Y fractures provided the favorable path for magma upwelling.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 127
EP 136
UT WOS:000393257900011
ER  

PT J
AU Li, N
Gong, LW
Zhao, YW
Fan, QC
Wang, JL
Zhang, CJ
AF Li Ni
Gong LiWen
Zhao YongWei
Fan QiCheng
Wang JiaLong
Zhang ChuanJie
TI Characteristics of volcanic geomorphology in Dalinor volcanic swarm and petrologic features of the volcanic rocks, Inner Mongolia
SO ACTA PETROLOGICA SINICA
AB The volcanic activities occurred pervasively in northeastern China in Cenozoic era. Four Quaternary volcanic swarms, Nuomin-Kuile River volcanic swarm, Halaha-Chaoer River volcanic swarm, Abaga-Dalinor volcanic swarm and Wulanhada volcanic swarm, locate from north to south along the western part of Daxing' anling-Taihangshan Gravity Lineament in Inner Mongolia Autonomous Region, extending more than 1000km. There were totally about 400 volcanoes and the area of volcanic rocks was more than 36000km(2). The numerous volcanic eruptions suggested the ever strongest intraplate volcanism in China. The Dalinor volcanic swarm, composed of a hundred volcanoes of varied sizes and shapes, is located on the Dalinor lava plateau between Xilinhot and Chifeng in the southeastern region of Inner Mongolia, whereas Abaga basalt and Beilike basalt are found northwest of this volcanic swarm. In the tectonic setting, the Dalinor volcanic swarm lies at the junction of the Xing' an and Songliao blocks, i. e. the composite section of the EW-trending Tianshan-Yinshan deep faults, the NE-trendin Daxing' anling-Taihangshan fault, and the NW-trending Abaga-Chifeng fault. Overall, the Dalinor volcanic swarm exhibits a step-shaped plateau, with the central portion at a higher elevation than the margins. The surface of the plateau is relatively flat, with a raised ridge and densely distributed volcanoes. Many newly formed volcanic cones are distributed on the lava ridge in the central area of the plateau, and are roughly arranged in an EW direction. Some of these cones exhibit a beaded distribution pattern striking in the NE direction. The area of the volcanic field is roughly 3100km(2). Most of the Dalinor volcanoes are central eruption or central-crevasse eruption style, leaving cluster of volcanic cones with height of 50-130m outstanding in the lava plateau, and the volcanic eruption materials covered and superimposed in the previous erupted lava tableland. The volcanic cones were denuded through the long-term geological evolution, among which the relatively young volcanoes, i.e. Gezishan volcano, kept a whole volcanic apparatus including cinder cone, crater, airfall and spatter deposit, lava flow, fumarole and invading dike, etc. In order to reveal the overall topographic undulation of the Dalinor volcanic swarm, two profile lines, 'A-B' and 'C-D' across the volcanic field, were drawn to traverse the lava plateau in the study area, with the crossing-point at the Da' aobao volcano. It can be seen both profile lines are relatively flat at the heights of 1280m, 1360m, 1440m and 1500m, exhibiting a clear step topography. The morphology measurement of a volcanic cone is an effective tool to determine the relative age of a volcano. It is well known that the height of a cone, the diameter of a crater, the depth of a crater pit, and the slope gradient of a cone's outer surface decrease with time, while the width of the crater wall rim and the diameter of the cone bottom consistently increase. The increase rate of the diameter of the cone bottom is much greater than that of the diameter of the cone top; namely, the difference between the diameter of the cone bottom and the width of the crater wall rim also continually increase over time. The ratio of cone height to diameter (H/D) was obtained by subtracting the cone bottom diameter from the crater diameter, which can reflect the formation time of a cone to a certain extent. Thus, the evolutionary process of a volcanic cone can be indicated in terms of a series of parameters, i.e.
the height of a cone, the diameter of a cone bottom, the crater rim, and the slope gradient of a cone. According to their geomorphology, the existing Dalinor volcanic cones could be roughly classified into four types: single truncated conical, composite, shield, and residual. The different denudation degree of the volcanic cones implies the relative eruption sequence of volcanic activities. Though the overall evolutionary process of a cone from new to old can be considered as conical shield residual, however, the existing cone morphology doesn't always match the eruption time. A composite volcano, for example, is rebuilt by multiple eruption episodes, its H/D value doesn't reflect its evolutionary sequence, and instead, its eruption age should be judged on the basis of careful field investigation. As the conical and composite volcanoes located in the central part of the plateau, the shield ones usually located in the margin, and the residual ones widely distributed in the volcanic field, which together indicate the volcanoes in the plateau margin formed earlier than those in the central, i.e. the volcanic eruptions migrated from the margins to the center of the lava plateau, while the even earlier large scale tholeiite overflowed and formed the base of the lava plateau. The lithology of Dalinor volcanic rocks is primarily basanite and alkali basalt, and some is trachybasalt. Though the SiO2 content of the rocks give a wide span (roughly 41% 49%), total alkali vary narrowly within 2%, ploting all above the alkali line in the TAS diagram. The rare phenocrysts, cryptocrystalline or microcrystalline matrix of the volcanic rocks make them quite different from the tableland-forming tholeiite indicated by adjacent Beilike basalt. The spider diagram of trace elements tilts to the right as a whole with LREE enriched and HREE deficit, suggesting the low degree partial melting of the magma. The similar trace element patterns between Dalinor and adjacent volcanic rocks imply they originated from roughly the same magma source, probably the asthenosphere, though Beilike basalt had some exceptions. The lithology of the volcanic rocks and relative eruption sequence instructed by denudation degree of volcanic cones demonstrate the magma evolved from alkali basalt and trachybasalt to basanite, and probably had a gradually deeper source with time.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 137
EP 147
UT WOS:000393257900012
ER  

PT J
AU Kang, M
Wang, LY
Zhu, XF
Chen, Y
Liu, XF
Yue, CC
AF Kang Ming
Wang LuYang
Zhu XueFeng
Chen Yu
Liu XiaoFeng
Yue ChangCheng
TI Study on fluid inclusions of the Xishanwanyangchang silver ore deposit in volcanic rocks, Inner Mongolia
SO ACTA PETROLOGICA SINICA
AB The Xishanwanyangchang silver ore deposit in volcanic rocks, lied in mid-west area of Inner Mongolia, is located in the northwest of the North China Plate. Hanging wall rock of the silver deposit is Permian biotite adamellite, and footwall rock is Cambrian tonalite. Silver polymetallic ore-bodies are lentiform or stratiform occurring in the rhyolite, rhyolite porphyry, and rhyolite breccia of lower series of Cretaceous Bainvyangpan Formation (K(1)bn) as well as contact zone of the volcanic rock and granite. The ores mainly have euhedral to subhedral granular, anhedral granular, metasomatie-relict and cataclastic textures and brecciated, disseminated, vein and massive structures. The mineralization mainly is ferritization, pyritization, fluoritization and mineralization associated with lead zinc. The sulfide mineral mainly consists of pyrite, and a small amount of argentite, acanthite, sphalerite and galena. The hydrothermal ore-forming process includes three stages, i.e. the early, middle and late stages, characterized by quartz-pyrite stage, quartz-polymetallic sulfides stage and quartz-carbonate stage, respectively. The main types of wall rock alteration include quartzitification, sericitization, chloritization, pyritization, limonitization, kaolinization, carbonatization. The gangue minerals are mainly composed of quartz, opal, chalcedony, fluorite, potash feldspar and a small amount of sericite. In quartz phenocrysts of rhyolite, three types of fluid inclusions can be observed, i.e. NaCl-H2O solution, the fluid inclusion containing halite daughter mineral and the fluid inclusion containing chalcopyrite daughter mineral. In early stage, homogeneous temperatures of fluid inclusions are mainly above 330 degrees C, with fluid salinities ranging from 0. 35% to 5. 86% NaCleqv, and the liquid-rich fluid inclusions are mainly observed, with high temperature and low salinity. In middle stage, homogeneous temperatures of fluid inclusions are mainly ranging from 250 degrees C to 330 degrees C, with fluid salinities ranging from 0. 35% to 31. 90% NaCleqv, and the fluid inclusions containing halite daughter mineral and the fluid inclusions containing chalcopyrite daughter mineral can be observed except liquid-rich fluid inclusions, characterized by the daughter mineral-bearing inclusions of high salinity coexisting with the liquid-rich fluid inclusions of low salinity. In late stage, homogeneous temperatures of fluid inclusions are mainly ranging from 169 degrees C to 250 degrees C, with fluid salinities ranging from 0. 71% to 32. 66% NaCleqv, and the fluid inclusions containing halite daughter mineral can be observed except liquid-rich fluid inclusions, characterized by the fluid inclusions containing halite daughter mineral of high salinity coexisting with the liquid-rich fluid inclusions of low salinity. The fluid inclusions containing chalcopyrite daughter mineral of high salinity in middle stage are resulted from boiled fluid, and the fluid inclusions containing halite daughter mineral of high salinity in late stage are preferably interpreted as being generated directly from a water-saturated crystallizing magmatic melt. The mineralization should be triggered by the temperature dropping and fluid mixing. Metal precipitation is mainly due to mixing between metal-bearing, high-salinity fluid and cold groundwater in the place where ores were deposited, resulting in enrichment and mineralization of the metal elements.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 148
EP 162
UT WOS:000393257900013
ER  

PT J
AU Pan, B
Fan, QC
Xu, JD
Wu, CZ
Chen, ZQ
Guo, F
AF Pan Bo
Fan QiCheng
Xu JianDong
Wu ChengZhi
Chen ZhengQuan
Guo Feng
TI Magmatic processes of the Millennium eruption at Changbiashan Tianchi volcano, China/North Korea
SO ACTA PETROLOGICA SINICA
AB Changbaishan Tianchi volcano on the border of China and North Korea is one of the most dangerous volcanoes in China and Northeast Asia. The Millennium eruption was considered as the youngest large-scale explosive eruption in China. After the recently geological survey around the caldera, we found the Millennium eruption has the comenditic and trachytic deposits with the magma mixing pumices showing the black and grey bands. Utilizing the further petrographic and geochemical studies, two eruptive phases have been identified out the "Millennium" eruption, comenditic eruptive phase (SiO2, 75%) and trachytic eruptive phase (SiO2, 65%). Meanwhile, the comenditic and trachytic magma were stored in two unconnected and separated chambers before eruption based on the entirely different feature on the trace element of the glasses and phenocrysts. The comenditic magma chamber was steadily stored and evolved in about 5km depth with 743 degrees C under the Tianchi caldera; while the trachytic magma chamber existed in 7 similar to 9km depth with 862 degrees C and was incrementally supplied with new magma from deeper source. In addition, the characteristics of the magma mixing strips suggest the mixing occurs in the rising channel excluding the possibility of chamber mixing. Finally, we build the model for the magmatic processes of the Millennium eruption based on the above results. In a word, we hope this improved recognition on the magmatic processes will benefit on the understanding of volcanic activity and assessment of volcanic hazards in future.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 163
EP 172
UT WOS:000393257900014
ER  

PT J
AU Zhou, ARGL
Dai, JG
Li, YL
Zhang, HL
AF Zhou AoRiGeLe
Dai JinGen
Li YaLin
Zhang HaiLong
TI Zircon trace element geochemical characteristics of Late Silurian-Early Jurassic granitoids from Eastern Kunlun Range and its geological significance
SO ACTA PETROLOGICA SINICA
AB In order to understand magmatism and tectonic evolution of the Eastern Kunlun Range, we conducted systematic Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) trace element analyses of zircons from the Paleozoic-Mesozoic granitoid rocks in the central and eastern segments of this range. The majority of zircons from the Late Silurian monzogranite and Late Permian, Late Triassic and Early Jurassic granites from the Eastern Kunlun Range possess high Tb/U (> 0. 5), and their chondritenormalized REE patterns of all zircons are characterized by HREE enrichment relative to LREE and MREE with distinctive positive Ce and negative Eu anomalies, which are typical of magmatic zircons. Zircons from the Late Silurian monzogranite and Late Permian, Late Triassic granites show small positive Ce anomalies and large negative Eu anomalies; while those from the Early Jurassic granites are characterized by large positive Ce anomalies, high Nb and Ta, low negative Eu anomalies. Zircons of the Late Permian granite have high total REE, Y, Th, U contents, whereas those of the Late Triassic granite have the highest Hf contents indicating that they might be the products of highly evolved magma. Some of zircons from the Late Silurian, the Late Permian, the Late Triassic and the Early Jurassic samples display LREE enrichments, indicating that they were probably metasomatized by LREE enriched melt from the subducted slab. All the zircons yield different Ti-in-zircon temperatures, but all of them are below 800 degrees C. This low crystallization temperatures indicate that the infiltration of the source region by a water-rich fluid should occur at a subduction zone. Combined with previous studies and the zircon U-Pb ages, these zircon trace elements provide new constraints on the Paleozoic-Mesozoic multi-stage tectonic-magmatic events of the Eastern Kunlun Range; (1) the origin of the Late Silurian monzogranite was related to the subduction of a small paleo-ocean and its magma source was derived from shallow crustal sedimentary basement; (2) the Late Permian granite was generated by the shallow crust partial melting induced by mantle magma above a subduction zone of the Paleo-Tethys; (3) the Late Triassic-Early Jurassic granites were formed during the collision between Qiangtang and Kunlun-Qaidam, and their source regions of the Late Triassic granite are shallower than those of the Early Jurassic granite.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 173
EP 190
UT WOS:000393257900015
ER  

PT J
AU Zhao, SW
Lai, SC
Qin, JF
Zhu, RZ
Gan, BP
AF Zhao ShaoWei
Lai ShaoCong
Qin JiangFeng
Zhu RenZhi
Gan BaoPing
TI The Petrogenesis and implications of the Early Eocene granites in Lianghe area, Tengchong Block
SO ACTA PETROLOGICA SINICA
AB The Mangdong and Qingmuzhai granites in Lianghe area, Tengchong Block, are important crust-derived magmatic products during the evolution of Neo-Tethys. The crystallization ages of granites are 48Ma to 51Ma, which is coeval to the Early Eocene acid and basic intrusions in Yingjiang area, western Tengchong Block. The granites in Lianghe area have high SiO2 and K2O contents, belonging to metaluminous to strongly peraluminous, high-K talc-alkaline S-type granite. In addition, the granites have high initial Sr-87/Sr-86 ratios and negative epsilon(Nd)(t) values, and the Nd model ages indicate that the provenances are Meso-Proterozoic. Furthermore, The Mangdong granites have high CaO/Na2O ratios and relatively low ratios of Al2O3/TiO2, Rb/Sr and Rb/Ba, but the Qingmuzhai granites have low CaO/Na2O ratios and relatively high ratios of Al2O3/TiO2, Rb/Sr and Rb/Ba. These signatures indicate that the Mangdong granites were derived from the metagreywackes but the Qingmuzhai granites were derived from the metapelite in the Tengchong lower-middle crust under the relatively high temperature condition. Coupled with the Mesozoic to Cenozoic magmatism in Tengchong Block, we propose that the Mangdong and Qingmuzhai granites formed in the compressive tectonic setting during the eastward initial collision or syn-collision of the India-Asia.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 191
EP 203
UT WOS:000393257900016
ER  

PT J
AU Liu, LL
Su, SG
Hou, JG
Xie, YC
AF Liu LuLu
Su ShangGuo
Hou JianGuang
Xie YuChun
TI Genesis of Tanling plagioporphyry in Wuan, Hebei: The remobilizing mechanism of frozen magma chambers
SO ACTA PETROLOGICA SINICA
AB Rheological experiments show that crystal-rich magma ("crystal mushes") will remain stable when the content of crystal is up to 50vol%. However, crystal-rich hypabyssal rocks and volcanic rocks are founded in the world. So the emplacement mechanism of crystal mush's ascending is one of the hot spot in earth sciences. There are two models about the remobilizing mechanism of frozen chambers: (1) thermal remobilizing mechanism; and (2) fluid-induced remobilizing mechanism. Plagioporphyry, which was founded recently in Tanling Wu'an, presents a new example for the study on Remobilizing Mechanism of Frozen Chambers (RMFC). Field observations and the analysis of crystal size distribution (CSD) show that Tanling plagioporphyry contains up to 70vol% plagioclase phenocrysts, and the size of phenocryst is similar to 3. 1 x 1. 7mm. The size of groundmass in plagioporphyry is very small (0. 05 similar to 0. 30mm), and it can be seen under microscope. Core content of plagioclase phenocrysts: the central part content of plagioclase phenocryst is An Ab(71) Or(2); the middle part content of plagioclase phenocryst is An(13)Ab(18)Or(4), the rim of plagioclase phenocrysts consists of perthite, the composition of host crystal is Ab(53)Or(47)-Ab(99)Or(1) and the content of guest crystal is Ab(48) Or(51)-Ab(3) Or(97). The spots amount of potassium feldspar decreases from the mantle to center of plagioclase phenocryst. The LA-ICP-MS trace element analysis reveals that the perthite rim of plagioclase phenocryst has weak positive Eu anomaly, much richer in K, Rb, Ba, Sr and poorer in Th, Nb and Zr. The relevant diagrams of CSD and all characteristics suggest that plagioclase phenocrysts have crystallized in a stable and closed environment. The minerals in groundmass consist of calcic amphibole, perthite, quartz, potassium feldspar, magnetite, ilmenite, apatite, sphene, rutile and zircon. Therefore, it is easy to judge that magma of groundmass was rich in K, Na, Fe, Si and volatile, which was identical with the forming condition of reaction rim. These features show that the perthite maybe formed by metasomation. We think that a fluid rich in alkali and iron injected into crystal-rich chamber, decreased the density of magma (crystal mushes) and accelerated the rapid reactivation of frozen magma.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 204
EP 220
UT WOS:000393257900017
ER  

PT J
AU Sun, YT
Guo, ZF
Cheng, ZH
Zhang, ML
Zhang, LH
AF Sun YuTao
Guo ZhengFu
Cheng ZhiHui
Zhang MaoLiang
Zhang LiHong
TI Gaseous anomalies related to the activities of Changbai Volcano in 2002 similar to 2005: Evidence from multi-sensor hyperspatial satellite archived data
SO ACTA PETROLOGICA SINICA
AB The Changbai Volcano is a volcanic area of potentially eruption dangerous in China. Enhanced volcanic activities and magma chamber disturbances occurred in 2002 similar to 2005. The remote sensing observation technology has the spatial and temporal advantages, which might be used in the volcanic monitoring and research. Thus the anomalies of CO total column (TotCO), total O-3 (TotO(3)), total H2O (TotH(2)O) and surface skin temperature (SKT) in the Changbai Volcano during the period from 2002 to 2005 were extracted from the archived data of Measurement of Pollution In The Troposphere (MOPITT) and Atmospheric Infrared Sounder (AIRS) hyperspectral satellite data. The results indicated it is well consistent of the multi-hyperspectral satellite data and the fluid observation in the field. Significant anomalies of TotCO(3) TotO(3), TotH(2)O, SKT and the corresponding standard deviation increased in 2002 similar to 2005, which indicate the gases degassing is temporal inhomogeneity. This might attribute to the degassing in the volcanic region under action of tectonic stress and volcanic activities. According to the field observation, the degassed gases were deduced might origin from the mantle. However, the migration of mantle materials did not last long period during the volcanic activities. The anomalies of SKT during the volcanic activities period might relate to the enhanced pulling-apart of faults in the area during the subduction process of Pacific slab beneath the Asian slab. Meanwhile, the results also show chemical reaction between the degassed gases and the components in the atmosphere. The results enriched the evidence from hyperspectral satellite data to the volcanic activities and favored the monitoring to the volcano activities.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 221
EP 230
UT WOS:000393257900018
ER  

PT J
AU Zhao, CP
Wang, Y
Zhou, Z
Li, ZP
Xing, LT
AF Zhao CiPing
Wang Yun
Zhou Zhi
Li ZhongPing
Xing LanTian
TI Present-day temperatures of magma chambers in the crust beneath Ninger volcanic field, southwestern China: Estimation from CO2-CH4 carbon isotope geothermometer
SO ACTA PETROLOGICA SINICA
AB Temperature is an important physical parameter of magma. To access and monitor temperature parameter of magma favors better understanding variations of the physical and chemical properties and behavior of magma, the evaluation of activity and eruption risk of a volcano. Volcanic magma and hydrothermal system enrich carbon bearing gases. Therefore the carbon isotopic thermometers can be employed to acquire the magma temperature of subsurface dormant volcano. Here we conduct 2 years of continuous and 2 times of parallel observation on carbon isotope composition of CO2 and CH4 of 4 thermal springs in highest strength of ground geothermal anomaly area in Ninger Volcanic Field (NVF). Using observational data, we identify whether CO2 and CH4 gases come from magma, and judge whether carbon isotope fractionation between CO2 and CH4 attain equilibrium. Using Horita CO2-CH4 carbon isotope equilibrium fractionation equation we calculate the source temperature of volcanic gases escape from the NVF. Our results show that, of 4 thermal springs in NVF, CO2 and CH4 from 1 are of non-magmatic origin, but that from the other 3 are mainly of magmatic origin, and that after excluding non-magmatic origin data, carbon isotope fractionation between CO2 and CH4 of the rest data attain equilibrium according delta-Delta plot method, and that gases source temperature of CO2 and CH4 of these 3 thermal springs are 425 similar to 475 degrees C, 941 similar to 995 degrees C and 1179 similar to 1578 degrees C, respectively. Combining our data and the uppermost crust temperature field results, we conclude that, there exist 2 magma chambers in NVF at present day, which located south to Ninger Volcano and north to Tongguan Volcano, respectively, that the temperature of Ninger magma chamber is up to 1179 similar to 1578 degrees C, that of Tongguan magma chamber, 941 similar to 995 degrees C, which reach to rhyolite (600 similar to 900 degrees C), andesites (800 similar to 1100 degrees C) and the basaltic magma (1000 similar to 1250 degrees C) formation temperature, and that intensive magnitude 6 earthquake cluster activity in space in Simao-Puer seismic zone can be explained by stronger activity level of Ninger magma chamber. The delta-Delta plot guidelines of determining the carbon isotope fractionation equilibrium between CO2 and CH4 should be amended as follows: under the conditions that the sign of the slope of the two fitting lines keep always opposite, the delta C-13(CO2) Delta(CO2-CH4) fitting straight line and the delta(13) C-CH4-Delta(CO2-CH4) one should intersect near the delta-axis with intercept difference Delta(b) <= 0.16.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 231
EP 249
UT WOS:000393257900019
ER  

PT J
AU Zhang, LH
Guo, ZF
Zheng, GD
Zhang, ML
Sun, YT
Cheng, ZH
Ma, XX
AF Zhang LiHong
Guo ZhengFu
Zheng GuoDong
Zhang MaoLiang
Sun YuTao
Cheng ZhiHui
Ma XiangXian
TI Flux and genesis of greenhouse gases emissions from Cenozoic volcanic-geothermal fields, South Tibet: A case study of volcanic-geothermal fields in Gulu-Yadong rift
SO ACTA PETROLOGICA SINICA
AB Gulu-Yadong rift (GYR) is the largest and longest extensional rift in Lhasa terrane, South Tibet. There are a lot of volcanic-geothermal fields in the rift, making it one of the strongest degassing areas in the India-Asia continental subduction zone. Following accumulation chamber method, we estimated the soil CO2 fluxes of Gulu and Yangying volcanic-geothermal fields. The results show that the average soil CO2 flux of Gulu geothermal field is 436. 8g . m(-2) . day(-1)which is similar with Yellowstone in America (410g . m(-2) . day(-1)), while the average soil CO, flux of Yangying is 99g m(-2) . day which is close to Mammoth Mountain volcano (107. 9g . m(-2) . day(-1)) in California, USA. According to the soil CO2 flux of the volcanic-geothermal fields in the GYR, we also estimate the total CO, emission of the Gulu-Yadong rift to be 1. 76 x 10(7)t . a(-1) these high soil CO2 emission suggests significant geological carbon degassing in India-Asia continental subduction zone at present. Based on the geochemical characteristics of the volcanic-geothermal gases from the GYR, both He-3/He-4 ratios (0. 10 similar to 0. 29R(A), R-A is the He-3/He-4 ratio of air) and delta C-13(CO2) values (7. 20 parts per thousand to 0.78 parts per thousand) of soil and bubbling gases display gradually increasing trends from south to north, implying significant difference in geodynamics processes along the GYR. In details, the increasing delta C-13(CO2) values from south to north might be related with variations of crustal lithology from south to north along the GYR. Additionally, most of the He-3/He-4 is higher than 0. 1R(A), implying significant mantle volatile contribution, and the progressively increasing He-3/He-4 from south to north might be related with the northward subduction of the Indian continental lithosphere.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 250
EP 266
UT WOS:000393257900020
ER  

PT J
AU Duan, WT
Huang, SP
Tang, XY
Zhang, J
AF Duan WenTao
Huang ShaoPeng
Tang XiaoYin
Zhang Jiong
TI Numerical simulation of the thermal diffusion of volcanic magmatism with ANSYS WORKBENCH
SO ACTA PETROLOGICA SINICA
AB Volcanic eruptions are associated with a vast amount of heat being carried from the interior to shallower depths by magmatism. Therefore, volcanic areas are generally rich in geothermal resource. Numerical simulation is an effective means not only in the research of thermo-tectonic evolution of the lithosphere, but also in the assessment of geothermal energy potential in a volcanic area. It is the objective of this paper to simulate the thermal effects of the magmatism with ANSYS WORKBENCH, a finite-element simulation software platform that has been widely used in engineering thermophysics, but so far rarely applied in a geological research. We first setup a series of simple cylindrical models to simulate the thermal diffusion process of intruded magma columns of different sizes and depths of intrusion. The cooling coefficient alpha = (T-intrusion - T)/(T-intrusion - T-steady) x 100% is introduced to evaluate the cooling degree of the intruded magma columns, and AT = T Tsteady to quantify the thermal disturbance of the intrusion to the country rocks. The result shows that the thermal relaxation time of a 0. 5km radius magma column is about 50ka, whereas that of a 1km radius column is around 200ka. The duration of thermal disturbance and horizontal range of a 0. 5km radius intruded column to the country rocks are less than 0. 5Ma and about 3km, respectively, as opposed to 1. 4Ma and about 7km of a 1km radius intruded column. The greater the depth of a magma column is buried, the shorter the duration its thermal disturbance to the country rocks lasts. Based on petrological and geophysical data from the Changbaishan volcanic area in NE China, we further construct two conceptual models to simulate the thermal effects of the Millennium Eruption of the Changbaishan Tianchi Volcano (CBTV) in NE China. The eruption of the CBTV in around 1000AD ejected about 100km(3) peralkaline rhyolites. It was one of the largest explosive eruptions in the world over the last 10000years. Petrological studies indicate that the erupted CBTV rhyolites were derived from the upper-middle crust at depths of about 10 similar to 15km; whereas recent magnetotelluric sounding and analysis of ALOS PALSAR satellite data suggest that the magma chamber is located in the upper crust beneath the depth of around 8km. Our two conceptual models represent the upper crust and upper-middle crust magma chamber scenarios, respectively. Simulation result shows that in either case, the thermal diffusion of the magma activity of the CBTV Millennium Eruption 1 ka ago are restrained within the range 500m from the intruded magma column. This might be part of the reason for the lack of widespread hydrothermal activities in the Changbaishan Tianchi vocanic area.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 267
EP 278
UT WOS:000393257900021
ER  

PT J
AU Zhang, L
Huang, SP
Fu, R
Tang, XY
AF Zhang Long
Huang ShaoPeng
Fu Rao
Tang XiaoYin
TI Application of magnetotellurics in geothermal exploration and research in volcano areas
SO ACTA PETROLOGICA SINICA
AB Magnetotellurics (MT) sounding is one of the most widely used geophysical exploration methods in volcanic areas for its wide exploration range and high sensitivity to geothermal reservoir related information such as temperature of rocks, abundance of geothermal fluid, extent of magma chamber, and lithostratigraphic strata. The electrical structure of the lithosphere is related with its thermal state. By analyzing the correlation, the geological structural model of the crust and the upper mantle can be built to enhance our understanding of the geodynamic mechanism of volcanic processes. In this paper, we first provide a brief introduction to the theoretical foundation of MT technology and the practical procedure from field data acquisition to data processing. The introduction is followed by an overview of the relationship between the electrical conductivity and temperature of the rocks. We then present several case studies from overseas to illustrate the application of the MT method in the geothermal exploration and the study of the thermal structure of the lithosphere in volcano Areas. For examples, in the Taupo volcanic area, New Zealand, MT sounding was used in the exploration of the Ngatamariki high geothermal field for hydrothermal resource in the upper 0 similar to 3km depths for power plant development; while in the Tendaho geothermal field in the Badi volcano in Afar Province, Ethiopia, the correlation between temperature and electrical structure from 0 similar to 20km and 0 similar to 50km were respectively analyzed, and the mechanism of volcanic formation and is discussed; in the Shinmoe-dake volcano in Kyushu, Japan, routine MT and temperature measurements have been used jointly to monitor volcanic activities. In the later part of this paper, we summarize the key MT sounding results from four major Cenozoic volcanic areas in China, namely, the Tengchong volcanic area in Yunnan Province, the Changbaishan Tianchi volcanic area in Jilin Province, the Wudalianchi volcanic area in Heilongjiang Province, and the Alershan volcanic area in the Inner Mongolia. We further employ the empirical temperature-electrical conductivity to constrain the temperatures of the crustal-mantle boundary for the Changbaishan-Tianchi volcanic area and the Alershan volcanic area, and possible magma chambers for the Changbaishan-Tianchi Volcano.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 279
EP 290
UT WOS:000393257900022
ER  

PT J
AU Zhou, XC
Sun, FX
Chen, Z
Lu, CJ
Li, J
Wu, KT
Du, JG
AF Zhou XiaoCheng
Sun FengXia
Chen Zhi
Lu ChaoJia
Li Jing
Wu KeTian
Du JianGuo
TI Degassing of CO2, CH4, Rn and Hg in the rupture zones produced by Wenchuan M-s 8. 0 earthquake
SO ACTA PETROLOGICA SINICA
AB Large amounts of greenhouse gases, radioactive gases and toxic gases (e. g. CO2, CH4, Rn and Hg) could be emitted from seismic active faults into the atmosphere with effect to the atmospheric environment. The flux of CO2, Rn and Hg along rupture zones were investigated by static chamber techniques and the total anualy output of CO2 and Hg to atmosphere were estimated. The results indicated (1) The maximum anomalies of CO2, CH4, Rn and Hg concentration in soil gas along co-seismic rupture zones reached values of 7. 98%, 2. 38%, 524. 30kBq/m(3) and 161. 00ng/m(3), respectively. The average flux of CO2, Rn and Hg from co-seismic rupture zones were 34. 95g . m(-2)d(-1), 36. 11mBq . m(-2)s(-1) and 26. 56ng . m(-2)h(-1), respectively. The maximum flux of CO2, Rn and Hg reached 259. 23g . m(-2) d(-1), 580. 35mBq . m(-2) s(-1) and 387. 67ng . m(-2) h (2) The total output of CO2 and Hg degassing estimated along siesmic ruptures were approximately 0. 95Mt . y(-1) and 15. 94kg . y(-1). The flux of CO2, Rn and Hg in soil gas were affected not only by the permeability of rupture zones, but also by gas sources from natural gas reservoir, coal seams and phosphat, etc.
SN 1000-0569
EI 2095-8927
PD JAN
PY 2017
VL 33
IS 1
BP 291
EP 303
UT WOS:000393257900023
ER  

EF  

黔ICP备07002071号-2
主办单位:中国矿物岩石地球化学学会
印刷版(Print): ISSN 1000-0569 网络版(Online): ISSN 2095-8927
单位地址:北京9825信箱/北京朝阳区北土城西路19号
本系统由北京勤云科技发展有限公司设计

手机扫一扫