Geochronology, Geochemistry and its Tectonic Significance of the Early Paleozoic Magmatic Rocks in Northern Langshan, Inner Mongolia

被引：6

作者：

Zhang Y. ^{[1
]}

Sun L. ^{[1
]}

Zhang T. ^{[1
]}

Teng F. ^{[1
]}

Zhang Y. ^{[1
]}

Sun Y. ^{[1
]}

Yang Z. ^{[1
]}

Xu F. ^{[2
]}

机构：

[1] Tianjin Center of China Geological Survey, Tianjin

[2] Hebei Institute of Regional Geological and Mineral Resource Survey, Langfang

来源：

Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | 2019年 / 44卷 / 01期

关键词：

Arc magmatic rocks; Early Paleozoic; Geochemistry; Northern Langshan; Inner Mongolia; Sr-Nd-Hf isotopic compositions; Zircon U-Pb geochronology;

D O I：

10.3799/dqkx.2018.305

中图分类号：

学科分类号：

摘要：

The Langshan area in Inner Mongolia is a paramount transitional zone located between the North China Craton (NCC) and the Xingmeng orogenic belt (XOB), and structurally belongs to the Early Paleozoic marginal accretionary belt in the northern margin of the NCC. The Early Paleozoic magmatic rocks distributed in the Bayinhanggai area, the northern Langshan, have important implications for the reconstruction of regional Paleozoic tectonic setting and orogenic evolution. The dioritic batholith consists mainly of diorite and quartz-diorite, with the zircon 206Pb/238U ages of 435.8±2.2 Ma-437.7±2.2 Ma, which represent the crystallization age of the Early Silurian. The rocks are calc-alkaline series, enriched in LREE with the (La/Yb)N ratios 4.30~11.59, depleted in HFSE (especially Nb, Ta and Ti) and enriched in LILE (like Rb, Th, K, Ba and Sr), and weakly negative Eu anomalies (δEu=0.80~0.96), indicating that they are formed in island arcs or in active continents margin setting. The Early Silurian diorite batholith shows depleted isotopic compositions, εHf(t)=+5.2-+12.6, (87Sr/86Sr)i=0.704 665-0.706 174, εNd(t)=+1.84-+2.00. Integrated geochronology, geochemical, Sr-Nd-Hf isotopic data and regional geological data suggest that the Early Silurian diorite batholith in northern Langshan was generated in Early Paleozoic and resulted from the southward subduction of Wenduermiao ocean along Wenduermiao-Wude-northern Suolun. The diorites were formed by partial melting of juvenile crust which was modified by subduction slab fluids. The determination of the Silurian arc magmatic rocks makes it clear that the northern Langshan area belongs to the Early Paleozoic active continental margin of the northern NCC, and it is the westward extended part of the Bainaimiao island arc belt. At the same time, it also provides important materials for the Early Paleozoic "trench-arc-basin" system in the west section of the northern NCC. © 2019, Editorial Department of Earth Science. All right reserved.

引用

页码：179 / 192

页数：13

共 48 条

[1] Ayers J., Trace Element Modeling of Aqueous Fluid-Peridotite Interaction in the Mantle Wedge of Subduction Zones, Contributions to Mineralogy and Petrology, 132, 4, pp. 390-404, (1998)
[2] Brenan J.M., Shaw H.F., Phinney D.L., Et al., Rutile-Aqueous Fluid Partitioning of Nb, Ta, Hf, Zr, U and Th: Implications for High Field Strength Element Depletions in Island-Arc Basalts, Earth and Planetary Science Letters, 128, 3-4, pp. 327-339, (1994)
[3] Regional Geology of Nei Mongol (Inner Mongolia) Autonomous Region, (1991)
[4] Chen B., Characteristics and Genesis of the Bayan Bold Pluton in Southern Sonid Zuoqi, Inner Mongolia-Typical Island Arc Magmatic Rocks Instead of Adakitic Rocks, Geological Review, 48, 3, pp. 261-266, (2002)
[5] Defant M.J., Drummond M.S., Mount St.Helens: Potential Example of the Partial Melting of the Subducted Lithosphere in a Volcanic Arc, Geology, 21, 6, (1993)
[6] Deng J.F., Feng Y.F., Di Y.J., Et al., Magamatic Arc and Ocean-Continent Transition: Discussion, Geological Review, 61, 3, pp. 473-484, (2015)
[7] Feng L.X., Zhang Z.C., Han B.F., Et al., LA-ICP-MS Zircon U-Pb Ages of Granitoids in Darhan Muminggan Joint Banner, Inner Mongolia, and Their Geological Significance, Geological Bulletin of China, 32, 11, pp. 1737-1748, (2013)
[8] Geng J.Z., Li H.K., Zhang J., Et al., Zircon Hf Isotope Analysis by Means of LA-MC-ICP-MS, Geological Bulletin of China, 30, 10, pp. 1508-1513, (2011)
[9] Harris N.B.W., Pearce J.A., Tindle A.G., Geochemical Characteristics of Collision-Zone Magmatism, Geological Society, London, Special Publications, 19, 1, pp. 67-81, (1986)
[10] Jahn B.M., Wu F.Y., Hong D.W., Important Crustal Growth in the Phanerozoic: Isotopic Evidence of Granitoids from East-Central Asia, Journal of Earth System Science, 109, 1, pp. 5-20, (2000)

← 1 2 3 4 5 →