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PT J
AU Li, SZ
Li, T
Zhao, SJ
Li, XY
Liu, X
Guo, LL
Yu, SY
Li, SJ
AF Li SanZhong
Li Tao
Zhao ShuJuan
Li XiYao
Liu Xin
Guo LingLi
Yu ShengYao
Li ShaoJun
TI Proto-Tethys Ocean in East Asia (IV) Deformation and evolution of microcontinents in the west segment of the northern Proto-Tethys Tectonic Domain.
SO ACTA PETROLOGICA SINICA
AB The North Qilian Orogen is a geological record of the Paleo-Qilian Ocean which is the west segment of the northern branch of the Proto-Tethys Ocean. The North Qilian Orogen underwent a complex orogenic process in the Early Paleozoic. However, the subduction polarity, closing time and assembly pattern are still on debate. Based on detailed structural analysis and compilation of the published metamorphic ages, three episodes of folding occurred during the Early Paleozoic are distinguished. The first-stage deformation is characterized by regional schistosity, gneissosity and mylonitic foliations, and it was formed due to the subduction-collision of the ancient Qilian oceanic crust during 489 similar to 442Ma. The second-stage deformation is marked by tight folds with South dipping axial planes, and it occurred with the exhumation of the subduction plate during 422 similar to 406Ma. The third -stage deformation is characterized by upright open folds. The first and second stages of deformation are overprinted by the third stage of deformation. The angular unconformity between the Ordovician-Silurian and the overlying Devonian strata widely distributes in the Qilian area. The comparison between the overlying and the underlying strata indicates that the deformation in the western part occurred earlier than that of the eastern part, implying a scissors -type closure of the Paleo-Qilian Ocean. In addition, the motion senses revealed by many 1 : 200000 geological sections across the entire study area indicate the southward subduction of the ancient Qilian oceanic crust. The subduction of the ancient Qilian Ocean started at 544Ma, and the collision between the Central Qilian and the Alax microcontinents began at 462Ma. The ancient Qilian Ocean closed at 442Ma. The west segment of the northern boundary of the Proto-Tethys Ocean retreated northward during the Early Paleozoic, possibly generating the jumping of subduction zones.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1615
EP 1632
UT WOS:000406212700001
ER  

PT J
AU Li, SZ
Li, T
Zhao, SJ
Li, XY
Liu, X
Guo, LL
Yu, SY
Li, SJ
AF Li SanZhong
Li Tao
Zhao ShuJuan
Li XiYao
Liu Xin
Guo LingLi
Yu ShengYao
Li ShaoJun
TI Proto-Tethys Ocean in East Asia (V) : Attribute of contientnal margin and microcontinental assembly in the west segment of the northern Proto-Tethys Tectonic Domain
SO ACTA PETROLOGICA SINICA
AB The branch of the Proto-Tethys Ocean in the Qilian Orogen is known as the Paleo-Qilian Ocean during the Early Paleozoic. Many continents/microcontinents, such as the Central Qilian, the Alxa, the Qaidam, the North China, the Yangtze and the Tarim blocks, located in and near the Paleo-Qilian Ocean, generating a complex archipelagic ocean. The Qilian area experienced a complex subduction-collision process in the Early Paleozoic. This paper discusses the tectonic attribute of the units in the Qilian Orogen. It is suggested that the southern Alxa Microcontinent was a passive continental margin, while the northern Central Qilian was an active continental margin during the Early Paleozoic. The Longshoushan tectonic unit, resulted from the subduction-collision process, is an accretionary wedge parallel to the southern Alxa. The North Qilian tectonic unit is a subduction accretionary complex composed mostly of high-pressure metamorphic rock, ophiolite, arc magmatite and some oceanic fragments. It records the evolution of the Paleo-Qilian Ocean from continental rifting, oceanic crustal growth, subduction and collision. The subduction zone of the Paleo-Qilian Ocean retreated northward due to the northward subduction of the Qaidam Microcontinent at about 495 Ma, forming the Dachadaban Arc. There was a subduction event occurring in the fore-arc area, forming the SSZ-type North Qilian ophiolite belts in the Dachadaban, the Baiquanmen and the Jiugequan, and a second magmatic event in the Qingshuigou, the Niuxinshan and the Yeniutan. The Paleo-Qilian Ocean began to close at 460Ma due to the collision between the Alxa and the Central Qilian microcontinents. The collisional process did not occur at the same time. The "scissor-like" collision model from west to east is more reasonable, accompanied by "S" type collision-related magmatite with the age lounging from west to east. The closure of the Paleo-Qilian Ocean terminated at 440Ma. Then the intracontinental orogenic stage started. Under an extensional environment after the collision, the magmatite formed in the Jinfosi, Niuxinshan, Laohushan and other places after 440 Ma. The retrograde metamorphism of HP eclogites and HP-LT blueschists occured as a result of the exhumation of the subducted plate during 422 similar to 406Ma, forming the second episode of deformation characterized by asymmetric tight fold. According to the analysis of the detrital zircon age spectra of different continents or microcontinents, it could be concluded that the basement of the Central Qilian Microcontinent is different form that of the North China Block, but may be associated with that of the Yangtze Block. The Central Qilian Microcontinent was far away from the North China and the Yangtze blocks as an independent microcontinent before the assembly of the Supercontinent Rodinia. Then the Central Qilian Microcontinent assembled to the Yangtze Block due to the formation of the Supercontinent Rodinia during 1. 0 similar to 0. 8 Ga, still far away from the North China Block. After the breakup of the Supercontinent Rodinia, the Central Qilian Microcontinent drifted away from the Gondwana, and gradually approached the North China Block. The Proto-Tethys Ocean closed during 500 similar to 400Ma, and the Alxa, the North China and the Central Qilian blocks assembled again to the northern margin of the Gondwana.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1633
EP 1652
UT WOS:000406212700002
ER  

PT J
AU Liu, JL
AF Liu JunLai
TI Strain localization and strain weakening in the continental middle crust
SO ACTA PETROLOGICA SINICA
AB Studies on the rheology of the continental lithosphere as the result of recent progress in the structural geology studies, forms the essential issue of developing plate tectonic theory, especially in the study of intraplate deformation and continental dynamics. The middle crust is of particular important in the deformation of the continental lithosphere. The domain is constituted mainly by granitic rocks and characterized by brittle -ductile transitional deformation. Rocks from the domain are deformed by both brittle and ductile deformation with various rheological strengths. It is shown that the middle crustal rocks have the following characteristics: 1) The middle crust flow is characterized by strain localization. 2) There are continental seismogenic zone in which most and strongest earthquakes are located, being indicative of a strong and weak middle crust. 3) Fluid/rock interactions are common, which directly influence the rheological properties of the rocks. 4) Geophysical investigations reveal the existence of low velocity and high conductivity layers in the middle crust. Strain localization is the most important characteristics of strain accumulation and concentration in the continental middle crust. It may occur at macro-, meso- and micro -scales. Strain softening of crustal rocks is the major triggering mechanism of strain localization. Different kinds of fluid -induced weakening mechanisms (e. g. hydraulic fracturing, reaction weakening and hydrolytic weakening etc.) and texture weakening (e. g. grain size reduction, preferred lattice orientation of crystals, banding of compositions) contributed significantly to strain localization. Rheology of the continental crustl rocks, middle crustal weakening and strain localization are key subjects for future studies of lithosphere rheology.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1653
EP 1666
UT WOS:000406212700003
ER  

PT J
AU Liu, S
Feng, CX
Feng, GY
Xu, MJ
Guo, XL
Feng, Q
Yan, J
Guo, Z
AF Liu Shen
Feng CaiXia
Feng GuangYing
Xu MengJing
Guo XiaoLei
Feng Qiang
Yan Jun
Guo Zhuang
TI Zircon U-Pb age, geochemical and Sr-Nd-Pb isotopic data: Constraints on the genetic model of the mafic dykes from the North China Craton
SO ACTA PETROLOGICA SINICA
AB Twelve mafic dyke swarms crop out in Hebei, Shanxi, Shandong, and Anhui provinces within the Taihang-Da Hinggan Mountains and Tan-Lu (Tan-Lu) magmatic belts, China. Here, we present new zircon LA-ICP-MS U-Pb age, geochemical, and Sr-Nd-Pb isotopic data for these dykes. The dykes formed between 128. 1 +/- 1. 2Ma and 115.0 +/- 0. 8Ma, and have typical doleritic textures. They are enriched in the light rare earth elements, some large ion lithophile elements (LILE; e. g., Rb, Ba, and Sr), Pb, and Th, and are depleted in Nb, Ta and Ti. The dykes have high initial 87 S r/86 Sr ratios (0. 7056 similar to 0.7105), negative eNd (t) values (-15.5 to -12. 4), relatively constant initial Pb isotopic ratios (16.45 similar to 16. 49, 15.44 similar to 15. 51, and 36.49 similar to 36.53 for Pb-206/ Pb-204, Pb-207/Pb-204, and Pb-208/(204) Pb, respectively), and relatively old Nd model ages (t(DM2)(Nd) =1.82 similar to 2. 69Ga). These results indicate that the dykes were derived from magmas generated by a certain extent partial melting (1. 0% similar to 5. 0%) of an EM1-like garnetlherzolite mantle source. These magmas fractionated olivine, clinopyroxene, and hornblende prior to emplacement, and assimilated minimal amounts of crustal material. Several possible models have been proposed to explain the destruction of the North China Craton (NCC) and the origin of Mesozoic magmatism. Here we propose a new model for the origin of these dykes, involving the foundering of eclogite from thickened lower crust and ongoing collision between the Paleo-Pacific Plate and the NCC.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1667
EP 1685
UT WOS:000406212700004
ER  

PT J
AU Kang, M
Yue, CC
Liu, XF
Chen, Y
Gao, C
Yuan, Y
AF Kang Ming
Yue ChangCheng
Liu XiaoFeng
Chen Yu
Gao Chao
Yuan Ye
TI Geochemical characteristics and tectonic setting for Mesozoic volcanic rocks in the Zha'ertai area, Inner Mongolia
SO ACTA PETROLOGICA SINICA
AB The Mesozoic volcanic rocks in the mid-west area of Inner Mongolia are mainly distributed in the Zha'ertai area, which is located in the northwest of North China plate. The Mesozoic volcanic rocks in the study area are divided into two types, which are formed in the two eruption cycles. The intermediate-to-basic volcanic rocks appear in early Early Cretaceous, and erupt as NEE trending eruption of fissure type along about EW deep fault; the acid volcanic rocks appear in late Early Cretaceous, and erupt as eruption of fissure type and central eruption along about SN fault. The intermediate-to-basic volcanic rocks, whose Si0(2) ranges from 49. 65% to 56. 64%, are mostly shoshonite and atite, and the acid volcanic rocks, whose Si02 ranges from 73. 18% to 83. 82%, include subvolcanic rocks, volcanic lastic rocks and volcanic lava, which is a typical bimodal distribution. The intermediate-to-basic volcanic rocks are characterized by high total alkaline contents (Na(2)0 + K2O = 6. 70% similar to 7. 47%), high-Ti (TiO2 = 2. 29% similar to 3. 55%), high-Fe, low-Ca, low-Mg, and the rocks are also enriched in large ion lithophile element (LILE) (Rb and Ba) and light rare earth elements (LREE) (LREE/HREE = 4.50 similar to 6.47) with highly fractionated LREEs and HREEs ( (La/Yb), = 4. 17 similar to 8. 85), with slightly negative Eu anomalies (8Eu = 0. 67 similar to 0. 96). Their geochemical characteristics are similar to those of oceanic island basalt (OIB), which implies that magma was mainly from asthenosphere, and the rocks did not experience obvious contamination of crustal materials. The acid volcanic rocks are characterized by high-Si, high -K, low-Ca, low-Mg, low-Fe, low-Ti, and the enrichment of large ion lithophile element (LILE) (Rb, Th and U), high field strength elements (HFSE) (Nb, Ta, Zr and Hf) and light rare earth elements (LREE) (LREE/HREE = 2. 91 similar to 14. 3), with highly fractionated LREEs and HREEs ( (La/Yb) N =2. 53 similar to 28.4, (La/Sm) N = 1. 16 similar to 4.57, (Gd/Yb) N = 1.22 similar to 5. 04), and with strong negative Eu anomalies (8Eu = 0.02 0. 25), which indicates that rhyolitic rock might be partial melting of crust-derived rock, stemming from partial melting of rocks in the pre-existing crust under plated by mantle-derived magma. On the basis of the regional geological background, it is concluded that the Mesozoic volcanic rocks in the study area are formed in the intracontinental extensional setting after the Siberian plate and the North China plate collision orogenetic period.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1686
EP 1704
UT WOS:000406212700005
ER  

PT J
AU Lu, YL
Peng, JT
Yang, JH
Hu, AX
Li, YK
Tan, HY
Xiao, QY
AF Lu YuLong
Peng JianTang
Yang JieHua
Hu A'Xiang
Li YuKun
Tan HuiYue
Xiao QiuYue
TI Petrogenesis of the Ziyunshan pluton in central Hunan, South China: Constraints from zircon U-Pb dating, element geochemistry and Hf-O isotopes
SO ACTA PETROLOGICA SINICA
AB The Ziyunshan pluton, located along the Xiangzhong basin in Hunan, consists mainly of porphyroid monzonitic granite and two-mica granite, the former is located in the surrounding of the pluton and constitutes its main intrusive granite, while the later occurs in its interior and belongs to late intrusive granite. The dark-colored mafic enclave with magmatic textures is usually observed in the intrusive bodies. The emplacement time of the Ziyunshan pluton is determined by high-precision SIMS zircon U-Pb dating. The main intrusive granite is dated at 225.2 +/- 1.7Ma and 225.6 +/- 1. 4Ma and the late intrusive granite is dated at 227.0 +/- 2. 2Ma, thus both granitic rocks were basically contemporary and emplaced during the Late Indosinian. Both two types of granite in this study are rich in SiO2(,) Na2O and K2O, and depleted in CaO, MgO and A(12)O(3), and its A/CNK index are 0. 85 similar to- 1. 05 with high consolidation index, 3. 61 similar to 5. 05 for the main intrusive ganite and 4. 13 similar to 14. 06 for the late intrusive granite. Both granitic rocks are characterized by Rb, U, La, Nd, Zr enrichment, and Ba, Nb, Ta, Sr, P, Ti depletion; the chondrite-normalized distribution pattern of REEs is characterized by "V"-shaped pattern, obvious LREE-enrichment ((La/Yb)(N) 7. 35 similar to 11.7) and negative Eu anomaly (delta Eu = 0. 32 similar to 0. 70). The zircon isotopes of both granites display similar signatures, the epsilon(Hf) (t) values of the Ziyunshan pluton display similar signatures-10.0 similar to-1. 6, and its delta(18) O values fall in the range of 7. 8 similar to 11. 4. The t(DM2) model ages are estimated at 1. 22 similar to 1. 79 Ga. The major oxides for all granite samples display good covariant relationships, and are obviously distributed along I-type granite evolution line, indicating threr are a intrinsic genetic relationship between the main intrusive granite and the late intrusive granite, both are of highly-differentiated I-type granite. All samples are distributed along the magmatic mxing trend line but away from the crystallization differentiation trend line, combined with the Hf-0 isotope resluts, it is shown that the Ziyunshan pluton was derived from the re-melting of Lower Proterozoic crustal meta-greywacke of Yangtze craton, and mixed with some mantle-sourced magma. The intrusive granite was formed under post-collision tectonic background, indicating South China block was subjected to the influences by both Pacific plate and Indosinian block under extension-thinning tectonic environment in the Late Indosinian. Compared with other Indosinian granites in South China block, it is considered that the suture region of Yangtze block and Cathaysia block lies along "Youxian-Shuangpai" region in Hunan.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1705
EP 1728
UT WOS:000406212700006
ER  

PT J
AU Yu, X
Yang, SF
Chen, HL
Li, ZL
Li, YQ
Qiu, ZL
AF Yu Xing
Yang ShuFeng
Chen HanLin
Li ZiLong
Li YinQi
Qiu ZhiLi
TI Petrogeochemical characteristics and geological implications of layered basalts from Xiahenan area, Tarim Basin
SO ACTA PETROLOGICA SINICA
AB The flood basalts from Xiahenan, Tarim Basin is mostly well-known for its horizontally layered exposure, which retains the relatively primary petrogenetic and diagenetic forms of the lavas and the intercalated sediments. It is the ideal outcrop for studying the Permian magmatism in Tarim Basin, also the best reference for other basaltic eruption events from other regions within the basin. This work introduces the field occurrence as well as lithologic and petrographic features of Xiahenan basalts based on detailed field observation and remote sensing interpretation. The geochemical characteristics of each basalt layer have been illustrated. The results show that the basaltic magma of Xiahenan were derived from an enriched lithospheric mantle, by low degree partial melting of spinet garnet lherzolite, followed with medium degree of fractional crystallization and lesser extent of crustal contamination. The geochemical diversity among basalts within a layer is attributed to fractional crystallization, while the geochemical variations between different layers are controlled by the degree of partial melting. All the layers of basalts from Xiahenan were originated from the same mantle source, which is also similar to Keping basalts, with a good correlation to six layers of Kaipaizileike basalts from Keping region. This study further clarified the spatial distribution of the Permian flood basalts in Tarim Basin, and confirmed that the basaltic magmatism of Tarim LIP extends from Keping region to Xiahenan, as well as to central and southwest Tarim Basin.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1729
EP 1740
UT WOS:000406212700007
ER  

PT J
AU Liu, R
Wang, LX
Chen, GW
AF Liu Rui
Wang LiXing
Chen GenWen
TI Genesis, geological significance and metallogentic potentiality of A -type granites in the Awulale area of the western Tianshan, Xinjiang
SO ACTA PETROLOGICA SINICA
AB The Qunji albite porphyry contains high SiO2(65.30% similar to 76. 93%), Na2O + K2O (6. 02% similar to 9. 66%) and FeOT/MgO (6.01 similar to 21. 4) and low A(12)O(3) (9. 82%similar to 15. 64%), Ca0 (0.47%similar to 1. 84%), Mg0 (0. 13% similar to 0. 45%) and is enriched in Th, U, Ta, Zr, Hf, Ga and Y. The porphyry has high Zr (468 x10 -6 - 707 x10, Y (20. 7 x10(-6) similar to 91. 4 x 10(-6)), Nb (21. 3 x10(-6) similar to 57.7 x 10(6), Ga (11.2 x 10(-6) similar to 19. 7 x 10(-6)) and Ce (36.7 x 10(-6) similar to 98.2 x 10(-6)) concentrations. Zircons from the porphyry are calculated to have saturation temperature >880 degrees C. All of these indicate that the Qunji albite porphyry has an affinity of A -type granite. The porphyry has low I-Sr(0. 70203 similar to 0.70549) and positive ENd (t = 303 Ma) value ( +4.1 to +5.2), and the whole rock Pb isotopic compositions are plotted in the field between the mantle and lower crust, indicating that the Qunji albite porphyry is likely sourced from the lower crust. The Qunji albite porphyry is therefore ascribed to the partial melting of the lower crust that was stimulated by the underplating basaltic magma from the asthenosphere, indicating an extension setting of this region in the late Paleozoic. The Qunji albite porphyry has potential of Cu mineralization. Zircons from the albite porphyry have low Ce4+/Ce3+ (19. 5 similar to 93. 0) with a mean value of 39. 6. The presence of euhedral and subeuhedral pyrite in the matrix indicates low oxygen fugacity of magma when the porphyry formed. The Cu mineralization was likely developed in a transition from oxidized S to reduced S, indicating that the parental magma of the Qunji albite porphyry is "dry", which has little potential for economic important porphyry Cu deposit.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1741
EP 1754
UT WOS:000406212700008
ER  

PT J
AU Jiao, QQ
Xu, DR
Chen, GW
Chen, YS
Zhang, JL
Gao, YW
Yu, LL
Zou, SH
AF Jiao QianQian
Xu DeRu
Chen GenWen
Chen YanSheng
Zhang JianLing
Gao YiWen
Yu LiangLiang
Zou ShaoHao
TI Zircon LA-ICP-MS U-Pb age of mylonite in the Hetai goldfield, Guangdong Province of South China and the geological implication
SO ACTA PETROLOGICA SINICA
AB The Hetai goldfield, located in Gaoyao area of Guangdong Province of South China, is a typical ductile shear related gold deposit. LA-ICP-MS U-Pb zircon dating on hydrothermal origin zircons from mylonite and protomylonite were carried out to constrain the metamorphism and deformation times of ductile shear zones, further to reveal the role of mylonitization in gold mineralization. Two weighted mean ages were obtained: an early sinistral ductile shearing at ca. 240Ma suggested by the hydrothermal zircon rims from mylonite; and a late dextral ductile-brittle shearing at ca. 204 Ma suggested by the hydrothermal zircon grains from protomylonite. Therefore, the Hetai goldfield was subjected to two Indosinian shearing events that are also common in South China. Given the published geochronology data of the Hetai goldfield, the gold mineralization ages (Yanshanian) significantly postdate the ductile deformation. The inherited zircons (the zircon cores) from the mylonite suggest that the Yunkai Group formed in early stage of Early Paleozoic rather than Precambrian. Moreover, it may be possible to determine the forming mechanism of hydrothermal zircon based on the distinction of Lu-Hf isotope between the hydrothermal and inherited zircon. The compositions of the Yunkai Group are associated to the magmatite that may have been derived from the remelting of 1.8Ga earth crust.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1755
EP 1774
UT WOS:000406212700009
ER  

PT J
AU Gao, Z
Zhang, GB
AF Gao Zhan
Zhang GuiBin
TI Geochronology of detrital zircons from metapelite of the North Qaidam UHPM belt and its geological implications
SO ACTA PETROLOGICA SINICA
AB The North Qaidam Ultrahigh -pressure Metamorphic (UHPM) belt is of great significance in revealing ancient tectonic activities to study the detrital zircon ages in metapelite. In this paper, we conduct LA-ICP-MS zircon U-Pb dating for metapelite from Luliangshan and Dulan in the North Qaidam UHPM belt. Detrital zircon ages show three groups of > 1100Ma, 1100 - 800Ma and 800 500Ma, representing the ancient continent nucleus, the collision and break-up of the supercontinent Rodinia and the evolution history of the Paleo-Qilian ocean. These similar data with the western Yangtze craton suggest that the Qaidam-Qilian might have been the western part of Yangtze craton. Compared with the present tectonic evolution of the Western Pacific Ocean, we conclude a new tectonic model: the North Qilian was an active continental margin and the North Qaidam was a passive continental margin in the Early Paleozoic; then, the North Qaidam turned to active continental margin after the ancient Qilian ocean closed on the north side of the Qilian terrane.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1775
EP 1788
UT WOS:000406212700010
ER  

PT J
AU Wen, QB
Liu, YJ
Gao, F
Li, WM
Feng, ZQ
Zhou, JP
Liang, CY
AF Wen QuanBo
Liu YongJiang
Gao Fei
Li WeiMin
Feng ZhiQiang
Zhou JianPing
Liang ChenYue
TI Thermochronological evidence for multi-phase uplifting and exhumation history the Jiamusi uplift in eastern Heilongjiang, China
SO ACTA PETROLOGICA SINICA
AB Jiamusi uplift has experienced multi-period plate collision events in eastern Heilongjiang Province and is an important part of the Jiamusi massif. Thermochronology study on its uplift history will help to deepen the understanding of the history of the collision and amalgamation of Northeast Blocks and the tectonic evolution of the Paleo-Asian Ocean. In this paper, by using zircon LA-ICP-MS dating, monazite Th-U-Pb CHIME dating and K-feldspar, biotite Ar-40-Ar-39 dating for the samples collected from the granite of Laopinggang pluton in Jiamusi uplift, we recovered the tectonic thermal evolution history of the multi-stage cooling and uplift of the Jiamusi uplift. Calculation results show that the Jiamusi uplift experienced three stage uplifts: first stage in the Early Paleozoic (511 similar to 494Ma), the second stage from 494Ma to 260Ma and the third stage in the Late Permian to the Middle Triassic (260 similar to 240Ma). During the first stage in the Early Paleozoic, the cooling rate was 11.76 degrees C/Myr and the uplift rate was 0.294mm/a, the total uplift amplitude reaches 5.00km, related to the collision event between the Jiamusi massif and the Songnen massif. During the second stage (from 494 260Ma), the uplift rate merely was 0.038mm/a and the corresponding cooling rate was 1.51 degrees C/Myr. The total uplift amplitude was only 8.80km, indicating a stable period. During the third stage in the Late Permian to the Middle Triassic (260 240Ma), the cooling rate was 8.44 degrees C/Myr and the uplift rate was 0.211mm/a, the total uplift amplitude averaged 4.22km, which should be related to the collision collage events between the Jiamusi massif and the North China Plate during the Late Permian to Middle Triassic.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1789
EP 1804
UT WOS:000406212700011
ER  

PT J
AU Bian, QT
Gai, SS
Liu, SY
Zhang, XS
Fu, CY
Guo, JT
Li, CB
Zhan, CF
AF Bian QianTao
Gai ShouShan
Liu ShaoYou
Zhang XueShu
Fu ChaoYi
Guo JiangTao
Li ChuanBan
Zhan ChangFan
TI Petrology and geochemistry of the Cu-bearing carbonatite from the Shivuma copper deposit, Zambia: Implications to petrogenesis and metallogeny
SO ACTA PETROLOGICA SINICA
AB An Iron Oxide-Copper-Gold (IOCG) carbonatite-type copper deposit was recently discovered near a village named Shivuma of Kasempa City of Northwest Province, Zambia. The deposit occurs at the intersection of a NW-striking deep fault and a NEE- to EW-striking fault, which are on the southern edge of the middle section of the synclinorium belt of the Lufilian Arc of the Pan-African orogen. The major strata are volcaniclastic rocks of the Kundelungu Group, which are on upper part of the Neo-Proterozoic Katanga Supergroup in the Cu deposit district, and igneous rocks are abundant, such as gabbro, diabase, gabbroic diorite, diorite, pyroxenite, lamprophyre, quartz-albitite and andesite. The major Cu-bearing rock is carbonatite, which varies in thickness from less than one centimeter to tens of meters and mainly intruded in the volcaniclastics. It has been observed that the carbonatite shows vesicular and flow structures, penetrates into and branches out in the country rock and contains xenoliths of volcaniclastics and andesite. The Cu-bearing carbonatite is greyish white, non-bedded, and dominantly of subhedral and fine-grained textures but mosaic and inclusion textures are also common. Calcite and dolomite are often twined. The mineralogy of the Cu-bearing carbonatite is complex with more than 40 minerals, with the major non-metal minerals being calcite followed by anhydrite, dolomite and fluorite, the major metal minerals being magnetite, chalcopyrite and pyrite, and subordinately pyrrhotite, sphalerite, molybdenite and bornite, and other silicates and rare earth minerals being also seen. The Cu-bearing carbonatite is wholly and unevenly mineralized with major ore structure being disseminated and taxitic, and subordinately massive and densely disseminated, and common ore textures being euhedral- to subhedral-fine-grained, anhedral-fine-grained, replacement-resorption, exsolution, sideronitic, mosaic, inclusion and border-sharing. The Shivuma copper deposit is featured with IOCG deposits and can thus be called IOCG carbonatite-type Cu deposit. The Cu-bearing carbonatite is characterized by higher contents of CaO (28.48% similar to 41.72%), FeO (3.91% similar to 20.95%) and Fez 03 (3.84% similar to 31.56%), and lower contents of Mg0 (0.68% similar to 2.51%) with CaO/MgO ratios ranging 10.5 similar to 60.0 and can thus be classified as ferrous calcite carbonatite. The REE concentrations of the Cu-bearing carbonatite are high with Sigma REE = 57.75 x 10(-6) 1076 x 10(-6) and LREE being richer than HREE with LREE/HREE ratios ranging 6.3 similar to 83.8 that results in the normalized distribution patterns tilting to the HREE end. High positive Eu anomalies (delta Eu = 2.92 similar to 11.1) and low negative Ce anomalies (delta Ce = 0. 68 similar to 0.83) are present. Metal sulfides and magnetite show similar REE patterns as the Cu-bearing carbonatite, an indication that they may have derived from the same source. The Cu-bearing carbonatite is enriched in Ba, Sr, Pb, U, Nb, P and REE but depleted in Ta, Zr, Hf and Ti, with Sr concentration varying from 147 x 10(-6) to 6360 x 10(-6) and an average of 3209 x 10(-6), and that of Ba varying from 13.2 x 10(-6) to 10600 x 10(-6) and an average of 3640 x 10(-6). The trace element geochemistry of the metal minerals is similar to that of the Cu-bearing carbonatite. Zr/Hf and Y/Ho rations and Y contents of the Cu-bearing carbonatite suggest that the rock belongs to a highly evolved magmatic system, transitional between pure melts and hydrothermal fluids.
The initial (Sr-87/Sr-86),(t = 530Ma) ratios of the Cu-bearing carbonatite vary from 0.705315 to 0.706708, being within the range of those for the major mantle-derived carbonatites across the world. The (Nd-143/Nd-144) 0 ratios of the Cu-bearing carbonatite and the massive copper ore occurred within the carbonatite are 5.11815 and 5.11718, and their epsilon(Nd) (t) values are -4.6 and -2.7, respectively. These Sr-Nd isotopic ratios probably indicate that the magma of the Cu-bearing carbonatite was derived from type I enriched mantle end-member (EM I). The (206)ph/(204)ph and Pb-207/Pb-204 ratios are unusually high, indicating that they belong to radiogenic lead. The delta(13) Cv-PDB values of the calcite from the Cu bearing carbonatite range from -17.8%o to -2.6 parts per thousand, and that of the dolomite is -18.8 parts per thousand, similar to those of carbonatite and diamond. The delta O-18(v-smow) values of the calcite vary from 14.5 parts per thousand to 21.9 parts per thousand, and that of the dolomite is 13.5 parts per thousand, all in the range of the carbonatites across the world. The delta O-18(v-smow) values measured for two magnetite samples are 4.3%o and 4.6 parts per thousand, close to the oxygen isotopic composition of the mantle. The delta S-34(V-CDT) values of the metal sulfides vary from -4.1 to +10.5, falling into the range of magmatic sulfur. The range of delta S-34(V-CDT) values for the anhydrite is from +14.2 to +15.5, similar to that of sulfur isotope of the sulfate from the porphyry copper deposits. In post-Pan-African orogeny, the region where the Shivuma copper ore deposit was discovered was under extension, and the lithosphere was subjected to tensional stress, and the deep faults were developed, resulting in partial melting of the upper mantle due to decompression. The partially melted upper mantle was an enriched EM I type mantle metasomatized by fluid rich in CO2. The initial melt was rich in volatiles, metallogenetic components and incompatible elements, but was relatively homogeneous at high temperature and pressure. It rose up into the crust along the deep faults and was separated into Si-unsaturated alkali silicate magma and carbonate-sulfate magma due to liquid immiscibility as the temperature and pressure deceased. Sulphophile elements such as Cu, Zn, Mo, Co, Ni, Au, Ag and Cd as well as Fe, which is both oxyphile and sulphophile, became enriched in the carbonate-sulfate magma. In addition, such magma contained lots of volatiles and incompatible elements. With further decease in temperature and pressure when the magma reached the shallow part of the crust, silicates, carbonates, sulfates and magnetite started crystallizing. At this time, because the oxygen fugacity was relatively high, copper and other heavy metal elements did not enter the crystal lattice but instead remained in the magma and became gradually enriched. Crystal differentiation enriched the volatiles and metallogenetic components more and more. When the volatiles got saturated or even oversaturated, liquid immiscibility took place, resulting in a transition-state fluid that contained solidified phase (minerals), isolated volatile phase and residual carbonate -sulfate melt phase. This liquid may be called Cu-bearing carbonatite magma-hydrothermal transitional fluid.
Part of such fluid that contained large amounts of metallogenetic components and volatiles intruded the weak and porous volcaniclastic rocks and decreasing temperatures allowed lots of carbonates, sulfates and magnetite to crystallize. When large amounts of oxygen was consumed, oxygen fugacity deceased and sulfur fugacity increased, resulting in reduced sulfur being combined with Cu, Fe, Zn, Co, Mo and other metal ions to form metal sulfides. At the beginning, metal sulfides were suspended in the Cu-bearing carbonatite magma-hydrothermal transitional fluid in the form of small drops and/or minerals. When more and more metal sulfides were crystallized, they might flow with the magma-fluid and created banded flow structure, and they might also replace early-crystallized magnetite. The Cu-bearing carbonatite magma-hydrothermal transitional fluid may form medium and fine veins of Cu-bearing carbonatite in the country rock and make the latter carbonatized and mineralized. At the final stage, the Cu-bearing carbonatite magma-hydrothermal transitional fluid completely solidified and formed whole-rock mineralized Cu-bearing carbonatites. When the contents of copper are up to the industrial grade, these carbonatites become orebodies. The copper orebodies are primarily reside in the Cu-bearing carbonatite; dense medium and fine veins of Cu-bearing carbonatite as well as carbonatized volcaniclastic rock can also form copper orebodies.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1805
EP 1826
UT WOS:000406212700012
ER  

PT J
AU Zhang, ZJ
Yang, TY
Yang, SH
Chen, L
Mao, Q
Ma, YG
He, WT
Ding, KS
AF Zhang ZhongJian
Yang TianYao
Yang SaiHong
Chen Li
Mao Qian
Ma YuGuang
He WanTong
Ding KuiShou
TI Sulfosalt minerals of Ag and Pb-Bi-Cu, and its directing significance for minerogenic temperature in Dongjun Pb-Zn-Ag deposit of Erguna district, Inner Mongolia, China
SO ACTA PETROLOGICA SINICA
AB Dongjun Pb-Zn-Ag deposit discovered in recent few years is located in Erguna district of Inner Mongolia, China. On the basis of open-air investigation, the mineralogical composition in the deposit and the contents of Ag, Au were determined by using EMP, SEM attached EDS, Atomic Absorption Spectra, ICPMS, etc. These minerals mainly include argentite, pyrostilpnite, freibergite, pyrargyrite, polybasite and stephanite. Moreover, some rare minerals such as tellurobismuthite, skinnerite, aikinite, krupkaite and certain unnamed Pb-Bi phase mineral were also discovered in rock. In order to estimate temperature of mineralize of the deposit, the chemical composition of tetrahedrite-Ag series in ore was analyzed. According to the value of Ag/(Ag + Cu) and Zn/(Zn + Fe), plotted on Sack' s isothermal curves. It is considered that Dongjun deposit should be an epithermal genesis, many non-silver sulfosalt and tellurobismuthite arose in deep orebody may be an important collateral evidence. This paper emphasized that the silver sulfosalt mineral with large grain in Dongjun deposit is beneficial. It is favorable for technological process and utilization of mine. However, the gold is only meaningful for geochemistry due to low production-grade.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1827
EP 1840
UT WOS:000406212700013
ER  

PT J
AU Zhao, B
Zhao, JS
Xu, DR
AF Zhao Bin
Zhao JinSong
Xu DeRu
TI Laser Raman analysis results of mineral inclusions from deposit of skarn type distributed in the Middle and Lower Reaches Metallogenic Belt of Yangtze River, China and their geological-geochemical significance
SO ACTA PETROLOGICA SINICA
AB Microthermometric data and phase compositions of melt and fluid-melt inclusions in a variety of silicate minerals from skarn deposits have led to proposal that a large amounts of skarns are of magmatic in origin of skarns. In this paper, we present results of Laser Raman spectroscoic analysis of melt inclusions and fluid-melt inclusions hosted in garnet and pyroxene from a number of skarn deposits along the Middle-Lower Yangtze Metallogenic Belt (MLYMB) to confirm the magmatic origin of the skarns investigated and associated Cu-Fe-Au deposits. Our results show that the melt inclusions contain only the solid phase and the trace gas phase. The fluid-melt inclusions contain, in addition to a large amount of solid phase, a trace fluid phase and a gas phase and a gas phase that is not detected by the instrument. The solid phases are of the same or similar to the host mineral of the inclusions, the fluid phases predominantly are water or salt aqueous solutions and gaseous phases including C6H6, C-3 H-6 C-3 H-8, CH4, CO2 and O-2. We suggest that the melt and fluid-melt inclusions are best representatives of the pristine magmas, and thus demonstrate the formation of the skarn assemblages by direct crystallization from a parent magma. In addition, we discuss the formation temperature, distribution range and scale of the magmatic skarns, the formation mechanism and the genetic relationship with Cu-Fe-Au mineralization.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1841
EP 1858
UT WOS:000406212700014
ER  

PT J
AU Shu, SP
Zhang, J
Chen, YJ
Li, L
Li, QG
Wang, QS
AF Shu SunPing
Zhang Jing
Chen YanJing
Li Lei
Li QiuGen
Wang QiSong
TI Discovery and geological significance of tellurides in the Herzhedegai gold deposit, Beishan metallogenic belt
SO ACTA PETROLOGICA SINICA
AB The Herzhedegai large-scale gold deposit is located in the Heiyingshan arc of the Beishan orogenic belt in Gansu Province. The auriferous quartz veins are mainly hosted in the faults/fractures of Early Carboniferous tonalite. The hydrothermal mineralization can be divided into three stages from early to late, namely, I-,- and 1(I-stage, which are characterized by (magnetite)-pyrite-quartz vein, auriferous quartz-polymetallic sulfide vein and quartz-carbonate vein, respectively. Based on optical microscope, scanning electron microscope analysis with energy dispersive spectroscopy (SEM + EDS) and electronprobe micro-analysis (EPMA), it was the first time that a large number of the tellurides were discovered in the II-stage ore samples. These minerals mainly occur in pyrite and quartz or in their fractures, consisting of calaverite, krennerite, sylvanite, petzite, hessite, altaite, coloradoite, tellurobismuthite and so on. Up to now, the discovered Au-Ag minerals are only occurring as Au- and Ag-tellurides. In I-stage of mineralization, the fluid system has relatively high sulfur fugacity (logfS(2) = 11.1 similar to -9.5) and low tellurium fugacity (logfTe(2) <= -12.8); in II-stage, the fluid system has relatively low sulfur fugacity (logfS(2) = 13.5 similar to -10.2) and high tellurium fugacity (logfTe(2) = 11.1 similar to -7.8). The discovery of the tellurides in the Herzhedegai gold deposit indicates its close relationship with the mantle, but the possible source of tonalite cannot be excluded.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1859
EP 1871
UT WOS:000406212700015
ER  

PT J
AU Zhang, SY
Zhang, HF
AF Zhang ShaoYing
Zhang HuaFeng
TI Element mobility and fluid characteristics during pyrophyllite alteration: A case study from the Baiyun pyrophyllite deposit, Wutai County, Shanxi Province
SO ACTA PETROLOGICA SINICA
AB Investigation on the element mobility during hydrothermal alteration processes can provide challenging insights into fluid properties and metallogeny. The Baiyun pyrophyllite deposit of the Wutai County, Shanxi Province, provides a natural case for study on fluid properties and elemental mobility, where the wall rocks mainly consist of albite-sericite quartz schist, associated with minor albite-chlorite schist. Hydrothermal alteration in the mine is dominated by pyrite-phyllic (sericite-quartz-pyrite) and pyrophyllite (pyrophyllite-illite-kaolinite-quartz). The gold mineralization is mainly developed in the pyrite-phyllic alteration zone. Log f(02)-pH diagram is constructed to depict the alteration process, and the phase diagram exhibites that the early pyrite-phyllic alteration fluid was weak acid to partial neutral (pH = 5.24 similar to 5.87) with relatively low oxygen fugacity (which was located in the stable area of pyrite and chalcopyrite). The alteration fluid leading to the pyrophyllite alteration, in contrast, was acidic (pH = 2.07 similar to 2.20) with relatively high oxygen fugacity (which was above the HM buffer line). According to the immobility of Al2O3 from the pyrophyllite ores, the mass balance calculation shows that the contents of SiO2, Na2O and K2O from the pyrophyllite ores are dramatically increased by comparison with the wall rocks (albite-sericite quartz schist), whereas, the other major oxides were prominently moved out. The abundances of Nb, Ta, Th, U, Rb, and Ga were relatively moved in, with Th/U ratios increased slightly. The abundances of Sr, Ba, Zr and Hf were relatively decreased with Zr/Hf ratios declined from 34 similar to 41 (wall rocks) to 17 similar to 22 (pyrophyllite ores). The rare earth elements were moved out as a whole, and the emigration amounts from LREE to HREE were gradually decreased. The Y/Ho (28 similar to 32) ratios are distinct with those of Cl chondrite (26 similar to 28), indicating that Y and Ho exhibit different behavior during pyrophyllite alteration. The negative Eu anomalies of the pyrophyllite ores are obvious, being attributed to decomposition of feldspars. The contents of Au and As within the albite-sericite quartz schist exhibit positive correlation ships with each other. By contrast, most metal ore-forming elements of the pyrophyllite ores are below the detected limit, suggesting the elements have been moved away during the pyrophyllite alteration. This phenomenon is consistent with the lithology features of pyrophyllite ores (visible harbor-shaped hematite and lacking of relevant pyrite). Our data indicates that the acidic and oxidized fluids can migrate amounts of so-called inactive elements, such as P, Ti, Zr, Hf, REE and other elements, simultaneously decoupled the ratios of Zr/Hf and Y/Ho during pyrophyllite alteration. Meanwhile, the fluids for pyrophyllite alteration leading to a superimposed destroy on the early formed gold mineralization, are not conducive for Au precipitation.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1872
EP 1892
UT WOS:000406212700016
ER  

PT J
AU Yang, ZY
Luo, P
Liu, B
Liu, C
Ma, J
Chen, FR
AF Yang ZongYu
Luo Ping
Liu Bo
Liu Ce
Ma Jie
Chen FeiRan
TI The difference and sedimentation of two black rock series from Yurtus Formation during the earliest Cambrian in the Aksu area of Tarim Basin, Northwest China
SO ACTA PETROLOGICA SINICA
AB It is generally believed that the black shale of Yurtusi Formation, one of the most potential hydrocarbon source rocks under Cambrian gypsum-salt bed in Tarim Basin, Northwest China, deposited in a uniform and similar sedimentary environment (slope facies), however, the results of the study are inconsistent with the above conclusions. In order to investigate the distribution and origin analysis of two black rock series observed in outcrop with completely different association of rock and mineral, and reconstruct respective depositional models, we conduct a detailed description and measurement of 12 profiles in the study area, from the perspective of sedimentology characteristics and identification of rock and minerals, combining with the methods of scanning electron microscope, XRD, and geochemical analysis, and focus on the study of the sedimentary and geochemical characteristic differences of two black rock series in Kule and Yutixi profiles. Sedimentary sequence, rock mineral assemblage, microelement enrichment coefficient, redox sensitive element ratio (V/(V + Ni), V/Cr, U/Th), REE + Y distribution pattern, organic matter content and saturated hydrocarbon chromatographic characteristics show that both sets of black shales, highly enriched in organic matter, are marine high-quality source rocks at the stage of thermal mature oil generation (kerogen type: II 1-II2; mean TOC of the first black shale: 5.37%, mean TOC of the second black shale: 1.46%), depositing in the reductive environment of seawater oxidation-reduction stratification, but the differences of their spatial distribution and control factors are larger. And then according to the conclusions above we establish two deposition models: one is the hydrothermal jet hypoxia model, and the other is the slope hypoxia model. The first black shale (thick in platform, thinn in platform margin), which is deposited in the inner ramp rifted sag with relatively deep water and high deposition rate during the period of transgressive peak (the first cycle), mainly controlled by hydrothermal exhalative activities, microbial processes and redox conditions, is wildly distributed and dominated by rifted sags in the center of the hydrothermal field near the platform or in the platform. Hydrocarbon-forming organisms of the first black shale are dominated by benthic algae, bacteria, supplemented by a small amount of planktonic algae, and its condition of development is more favorable in platform sag. While, the second black shale (stable and thick in outer ramp, pinch-out in the inner of platform), which is deposited in low energy zone of outer ramp with deepening water during the period of early transgressive (the second cycle), mainly controlled by paleo-productivity, redox conditions and paleotopography (slope gradient), is locally distributed. Hydrocarbon-forming organisms of the second black shale are dominated by the phytoplankton, supplemented by microbes and lower hydrobiont, and its condition of development is more favorable in outer ramp of platform margin.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1893
EP 1918
UT WOS:000406212700017
ER  

PT J
AU Li, Y
Liang, WT
Jin, CS
Dong, YP
Yuan, HL
Zhang, GW
AF Li Yang
Liang WenTian
Jin ChunSheng
Dong YunPeng
Yuan HongLin
Zhang GuoWei
TI Rock-magnetism, magnetic fabric and kinematic vorticity analysis of the Shagoujie shear zone, Qinling orogen
SO ACTA PETROLOGICA SINICA
AB The Shagou shear zone, located in the Shangdan belt of East Qinling, is characterized by ductile deformation, which can contribute to constrain the Late Triassic tectonic setting of the Qinling orogen. In order to probe its kinematics and further to explore the dynamic mechanism, mylonite samples were analyzed in terms of anisotropy of magnetic susceptibility (AMS) and kinematic vorticity W-k) on the basis of the field observations and microstructural analyses. The values of mean susceptibility (K-m) show a wide variation range, which means that the ferromagnetic mineral like magnetite acted as the dominant magnetic carrier of the samples. The corrected anisotropy degree (P-J) are relatively large indicative of a strong structural deformation. Shape parameter (T) are generally more than zero, indicating that the susceptibility ellipsoid of the Shagoujie shear zone is mainly oblate. Magnetic fabrics, defined by AMS ellipsoids, is relatively well consistent with the mineral fabrics. Combined with the magnetic fabrics and the attitude of the boundary fault or the C-foliation, it can be concluded that the Shagoujie shear zone showing a sinistral transpressional kinematic. Furthermore, Wk and its distribution patterns reflect that the core of the Shagoujie shear zone is located in northern boundary fault, and it also demonstrates that pure shear component is the dominant shear force during the formation process of the Shagoujie shear zone. Taken together, the kinematics of the Shagoujie shear zone suggest that it was formed in a local transpressional setting under oblique convergence. What's more, Late Triassic bilateral extrusion tectonics of the Qinling orogen may explain the plain fact that the Shagoujie shear zone has a completely opposite kinematic with the coeval shear zone located in the western Shangdan belt.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1919
EP 1933
UT WOS:000406212700018
ER  

PT J
AU Wang, J
Chen, Y
Mao, Q
Li, QL
Ma, YG
Shi, YH
Song, CZ
AF Wang Juan
Chen Yi
Mao Qian
Li QiuLi
Ma YuGuang
Shi YongHong
Song ChuanZhong
TI Electron microprobe trace element analysis of rutile
SO ACTA PETROLOGICA SINICA
AB Synthetic oxides are commonly used as the monitor standards for the trace element analysis of rutile by Electron Probe Microanalyzer (EPMA). Systematic analyses of rutile standards are still lacking. In this study we present a detailed EPMA analysis (CAMECA SXFive) on nine elements (Al, Si, Ti, Fe, Cr, Zr, V, Nb and Ta) in the rutile standard R10. Ti and Si are used as monitor elements. To improve the analytical precision and reduce the detection limit, we have critically adjusted the acceleration voltage, beam current and counting time, and have deducted the interference peak signals. Our results show that the concentrations of Zr (780 +/- 29 x10(-6)) (1SD, n=25), Nb (2799 +/- 66 x10(-6)), V (1276 +/- 33 x10(-6)), Fe (4309 +/- 34 x10(-6)) and Cr (718 +/- 31 x 10(-6)) are well consistent with those analyzed by Secondary Ion Mass Spectrum (SIMS) or Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) within the error range. EPMA analysis in this study exhibits good stability. From a one-month monitoring period, the variations of Nb, Zr, and Cr are within 10%, whereas the variations of V and Fe are within 5%. Our modified techniques improved the analytical precisions of V, Nb and Fe in rutile. The analytical precision of Zr in this study would not significantly affect the results yielded by the Zr-in-rutile thermometer. Therefore, EPMA trace element analysis is an effective approach to understand the formation mechanisms of rutile. The techniques that can potentially improve the analytical precisions of Ta and Fe3+ analyses in rutile are also discussed.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1934
EP 1946
UT WOS:000406212700019
ER  

PT J
AU Sun, JB
Chen, W
Yu, S
Shen, Z
Tian, YT
AF Sun JingBo
Chen Wen
Yu Shun
Shen Ze
Tian YunTao
TI Study on zircon (U-Th)/He dating technique
SO ACTA PETROLOGICA SINICA
AB Zircon (U-Th)/He dating is an important method of thermochronometry and it is indispensable to recording the complete thermal history of geological bodies. It has been widely used in geological researches such as volcanic rock dating, constraining evolution of orogenic belts, landform, sedimentary basins and hydrothermal activities. Zircon (U-Th)/He dating method, which including sample preparation, He analysis and U, Th analysis, has been established in laboratory of Institute of Geology, Chinese Academy of Geological Sciences (CAGS). Analytical precision on He isotope ratio measurement of zircon is about 0.1%, and U, Th isotope ratio measurements are typically <1%. Fish Canyon Tuff (FCT) zircon and Sri Lanka zircon, which are commonly used as standard for zircon (U-Th)/He dating, have been dated by using the newly established experimental procedure. All 27 ages of FCT zircons range from 25.81Ma to 30.72Ma, with a weighted mean age of 28.18 +/- 0.51Ma (1 sigma) (reference value is 28.3 +/- 2.6Ma); All 20 ages of Sri Lanka zircons range from 445.5Ma to 489.5Ma, with a weighted mean age of 479.0 +/- 8.0Ma (1 sigma) (reference value is 470 +/- 11Ma). The ages of two standards are consistent with their reference value, indicating that the experimental procedure we established is accurate and reliable. The establishment of this dating method fills the blank of zircon (U-Th)/He dating method, and provides a new technical support for the development of thermochronology in China.
SN 1000-0569
EI 2095-8927
PY 2017
VL 33
IS 6
BP 1947
EP 1956
UT WOS:000406212700020
ER  

EF  

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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
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