Petrogenesis and Tectonic Implications of Carboniferous Granites and Its Dark Enclaves in the Western Awulale Mountain, Western Tianshan
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Abstract:
The petrogenesis and dynamic background of the magmatic rocks in the West Tianshan Mountains are of great significance to reveal the tectonic evolution history of the restoration area. In this paper, the granite and its dark enclaves in the northwestern area of Kunes Zhongyangchang in the western Awulale Mountain were selected for petrology and zircon U-Pb chronology and petrogeochemical analysis. The results show that the dark enclaves are fine-grained diorite, with K2O=0.93~2.50, K2O/Na2O=0.20~0.21, A/CNK=0.83~0.87 and σ=2.33~3.02, which are quasi-aluminous calc-alkaline rock series. Host granites belong to I type granites with K2O=2.92~3.48, K2O/Na2O=0.60~0.79, Ritman index σ=1.87~2.17, and A/CNK =1.01~1.04, which are weakly peraluminous calc-alkaline rock series. Both of them are enriched in large ion lithophile elements (LILE, e.g. Rb、Ba、Pb) and depleted in high field strength elements (HSFE, e.g. Nb, Ta, Ti), The total amount of rare earth elements is low, accompanied by the relative enrichment of light rare earth elements, and the relative loss of heavy rare earth element. The diorite enclaves have no significant Eu and Sr anomalies, while the granites have obvious negative Eu anomalies and strong loss of Sr, P and Ti elements. Zircon U-Pb dating shows that the formation age of granite is (320.0±2.7) Ma, belonging to the early Late Carboniferous. The diagenetic age of the diorite enclaves is (344.5±1.4) Ma, belonging to the Early Carboniferous. The type of diorite enclaves is xenolith, which were captured during the rising of the host granitic magma. The geochemical and chronological characteristics of the rocks reveal that they have different petrogenesis. The dioritic enclaves were formed during the northern Tianshan Ocean subduction southward, and the granite intrusion was located in the post-collision extension environment, which was formed due to the upwelling of the asthenosphere, leading to the partial melting of the lower crust. Based on regional geological data, it is likely that the early Carboniferous to late Carboniferous is an important stage of tectonic system transformation in the western Tianshan Mountain, that is, the tectonic environment transformed from compression to extension.
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测点 含量(10−6) Th/U 同位素比值 年龄(Ma) Th U 1σ 207Pb/235U 1σ 206Pb/238U 1σ 207Pb/206Pb 1σ 207Pb/235U 1σ 206Pb/238U 1σ 1 207 229 0.91 0.0530 0.0024 0.3685 0.0167 0.0504 0.0003 327.5 102.6 318.5 14.5 317.3 2.1 2 140 159 0.88 0.0531 0.0037 0.3821 0.0265 0.0522 0.0004 333.0 156.0 328.6 22.8 328.0 2.3 3 156 196 0.80 0.0534 0.0025 0.3742 0.0181 0.0508 0.0004 347.3 107.3 322.8 15.6 319.4 2.5 4 289 226 1.28 0.0529 0.0018 0.3838 0.0130 0.0526 0.0004 326.1 75.6 329.8 11.2 330.4 2.2 5 191 187 1.03 0.0533 0.0027 0.3693 0.0188 0.0502 0.0003 342.6 114.6 319.1 16.2 315.9 2.1 6 159 166 0.96 0.0536 0.0034 0.3715 0.0239 0.0503 0.0004 354.7 144.1 320.8 20.6 316.1 2.3 7 344 297 1.2 0.0536 0.0014 0.3832 0.0103 0.0519 0.0003 353.6 59.9 329.4 8.9 325.9 2.1 8 137 168 0.82 0.0528 0.0027 0.3721 0.0194 0.0511 0.0004 321.2 117.6 321.2 16.8 321.2 2.3 9 272 263 1.04 0.0531 0.0019 0.3827 0.0136 0.0522 0.0003 334.8 79.3 329.0 11.7 328.2 2.2 10 206 242 0.86 0.0536 0.0025 0.3703 0.0177 0.0501 0.0003 354.5 106.5 319.9 15.3 315.1 2.2 11 141 161 0.88 0.0532 0.0040 0.3637 0.0272 0.0496 0.0004 335.3 169.5 315.0 23.6 312.2 2.5 12 64 102 0.63 0.0533 0.0041 0.3624 0.0281 0.0493 0.0005 343.0 174.6 314.0 24.3 310.2 2.9 13 122 162 0.76 0.0529 0.0020 0.3729 0.0153 0.0511 0.0004 339.7 87.4 309.1 12.2 305.1 2.2 14 93 120 0.78 0.0528 0.0051 0.3773 0.0362 0.0518 0.0004 324.9 87.2 321.8 13.2 321.4 2.8 15 101 136 0.75 0.0529 0.0032 0.3772 0.0228 0.0517 0.0004 319.9 218.2 325.0 31.2 325.8 2.7 16 70 133 0.53 0.0538 0.0045 0.3720 0.0312 0.0502 0.0004 274.3 234.9 266.9 27.2 266.0 2.3 17 73 111 0.66 0.0536 0.0064 0.3734 0.0445 0.0505 0.0005 325.9 136.7 325.0 19.6 324.9 2.8 18 123 193 0.64 0.0536 0.0029 0.3665 0.0199 0.0496 0.0003 360.6 188.0 321.2 26.9 315.8 2.6 19 101 129 0.78 0.0533 0.0026 0.3701 0.0184 0.0504 0.0004 354.2 267.7 322.1 38.4 317.7 3.0 20 80 99 0.81 0.0532 0.0037 0.3746 0.0270 0.0511 0.0006 563.1 92.5 361.4 15.5 330.7 2.2 21 160 150 1.07 0.0534 0.0023 0.3791 0.0166 0.0515 0.0004 353.3 123.1 317.0 17.3 312.1 2.1 22 14 215 0.06 0.0589 0.0025 0.4275 0.0184 0.0526 0.0004 341.3 111.2 319.7 15.9 316.8 2.7 23 176 164 1.07 0.0535 0.0031 0.4047 0.0235 0.0548 0.0004 351.1 131.6 345.1 20.1 344.2 2.8 24 82 94 0.88 0.0534 0.0020 0.4034 0.0157 0.0548 0.0005 335.8 158.8 323.1 23.3 321.3 3.7 25 60 87 0.69 0.0534 0.0025 0.4010 0.0198 0.0545 0.0007 343.8 84.8 344.1 13.4 344.1 3.4 26 205 198 1.03 0.0530 0.0022 0.3934 0.0165 0.0538 0.0004 344.9 107.0 342.3 16.9 342.0 4.6 测点 含量(10−6) Th/U 同位素比值 年龄(Ma) Th U 207Pb/206Pb 1σ 207Pb/235U 1σ 206Pb/238U 1σ 207Pb/206Pb 1σ 207Pb/235U 1σ 206Pb/238U 1σ 1 150 284 0.53 0.0538 0.0033 0.4050 0.0258 0.0546 0.0004 361.5 140.3 345.3 22.0 342.9 2.6 2 239 344 0.69 0.0014 0.0014 0.4825 0.0128 0.0636 0.0004 413.7 57.7 399.8 10.6 397.4 2.7 3 157 284 0.55 0.0540 0.0020 0.4086 0.0153 0.0549 0.0003 371.8 83.7 347.8 13.0 344.3 2.1 4 153 262 0.59 0.0533 0.0026 0.4000 0.0195 0.0545 0.0003 340.0 111.1 341.6 16.7 341.8 2.0 5 218 413 0.53 0.0543 0.0016 0.4091 0.0125 0.0547 0.0003 382.3 67.9 348.2 10.6 343.1 1.9 6 225 424 0.53 0.0538 0.0023 0.3953 0.0168 0.0533 0.0003 364.3 95.3 338.2 14.4 334.5 2.0 7 256 369 0.69 0.0537 0.0016 0.4107 0.0125 0.0555 0.0003 356.9 67.3 349.4 10.6 348.2 1.9 8 311 505 0.62 0.0542 0.0016 0.4076 0.0119 0.0546 0.0003 377.7 64.8 347.2 10.1 342.6 2.0 9 426 597 0.71 0.0535 0.0010 0.4082 0.0082 0.0553 0.0003 351.3 44.0 347.6 7.0 347.0 2.2 10 139 929 0.45 0.0539 0.0014 0.4122 0.0103 0.0555 0.0003 365.1 56.8 350.4 8.8 348.2 1.9 11 232 366 0.63 0.0537 0.0012 0.4102 0.0096 0.0554 0.0003 360.5 51.5 349.0 8.2 347.3 2.0 12 170 347 0.49 0.0535 0.0016 0.4045 0.0124 0.0549 0.0003 348.7 68.7 344.9 10.6 344.3 2.0 13 135 237 0.57 0.0534 0.0030 0.4056 0.0229 0.0550 0.0003 347.7 125.5 345.7 19.5 345.4 2.2 14 294 402 0.73 0.0541 0.0015 0.4096 0.0117 0.0549 0.0003 375.2 64.2 348.6 10.0 344.6 2.2 15 195 348 0.56 0.0540 0.0020 0.4066 0.0150 0.0546 0.0003 370.6 82.5 346.4 12.8 342.8 2.0 16 147 285 0.52 0.0536 0.0020 0.4058 0.0155 0.0550 0.0003 352.2 85.2 345.8 13.2 344.9 2.0 17 110 346 0.32 0.0539 0.0016 0.4130 0.0128 0.0555 0.0003 368.2 67.9 351.0 10.9 348.4 2.1 18 205 404 0.51 0.0540 0.0013 0.4077 0.0103 0.0547 0.0003 372.2 56.1 347.2 8.7 343.5 2.0 19 243 426 0.57 0.0541 0.0015 0.4054 0.0114 0.0544 0.0003 374.5 62.1 345.5 9.7 341.2 1.9 20 200 319 0.06 0.0536 0.0020 0.4037 0.0148 0.0546 0.0003 353.3 82.4 344.3 12.6 343.0 1.9 21 136 256 0.53 0.0536 0.0020 0.4040 0.0147 0.0546 0.0003 356.0 82.2 344.6 12.6 342.9 2.0 22 180 421 0.43 0.0537 0.0012 0.4104 0.0094 0.0554 0.0003 357.9 50.8 349.2 8.0 347.9 2.2 23 320 516 0.62 0.0540 0.0013 0.4039 0.0101 0.0543 0.0003 332.2 75.8 350.1 12.0 352.8 2.0 24 271 457 0.59 0.0537 0.0013 0.4114 0.0098 0.0556 0.0004 369.1 55.4 344.5 8.6 340.8 2.0 25 266 559 0.48 0.0541 0.0014 0.4122 0.0103 0.0552 0.0003 363.6 66.4 341.5 10.2 338.3 1.9 26 181 349 0.52 0.0537 0.0015 0.4047 0.0115 0.0546 0.0003 357.3 54.0 349.8 8.3 348.7 2.3 27 126 281 0.45 0.0540 0.0025 0.4097 0.0192 0.0550 0.0003 377.2 56.2 350.4 8.8 346.4 2.0 28 202 387 0.52 0.0538 0.0016 0.4120 0.0125 0.0555 0.0003 360.6 62.6 345.1 9.8 342.8 2.0 29 226 395 0.57 0.0538 0.0015 0.4080 0.0112 0.0550 0.0003 371.9 105.6 348.7 16.4 345.2 2.2 30 239 344 0.69 0.0550 0.0014 0.4825 0.0128 0.0636 0.0004 363.3 67.0 350.3 10.7 348.4 2.0 31 226 395 0.57 0.0538 0.0015 0.4080 0.0112 0.0550 0.0003 363.7 61.3 347.4 9.5 345.0 2.0 样品 13XY-13h 13XY-29h 13XY-30h 13XY-31h 13XY-32h 13XY-24-1h 13XY-24-2h 13XY-24-3h 13XY-24-4h 样品 13XY-13h 13XY-29h 13XY-30h 13XY-31h 13XY-32h 13XY-24-1h 13XY-24-2h 13XY-24-3h 13XY-24-4h 闪长质包体 寄主花岗岩 闪长质包体 寄主花岗岩 SiO2 57.03 59.44 57.05 56.72 57.77 75.48 75.34 74.57 73.5 Zn 48.5 35.6 41.2 52.8 40.7 16.8 18.7 17.2 14.4 Al2O3 16.01 15.93 16.23 15.91 16.51 12.91 12.86 13.27 13.44 Cr 50.6 17.5 0.63 3.39 13.7 7.01 9.18 10 4.43 Fe2O3 3.39 3.41 3.4 2.17 3.55 0.82 0.85 0.8 0.82 Ni 15.3 8.02 3.79 10.6 9.26 1.18 2.7 2.2 1.49 FeO 5.26 4.2 6.15 7.18 4.65 1.01 0.96 1.07 1.48 Co 22.3 14.3 19.7 24.2 17.2 2.1 2.45 5.02 7.34 CaO 5.77 5.16 5.36 6.13 5.21 0.81 0.87 1.06 0.93 Li 7.49 6.15 5.42 4.41 6.48 2.46 2.04 1.91 3.83 MgO 3.71 2.82 3.2 3.68 3.08 0.27 0.26 0.35 0.54 Rb 39.7 34.2 12.8 14 29.5 57.5 66 44.8 48.9 K2O 1.98 2.18 0.93 1.05 2.5 3.29 3.48 2.92 3.44 Cs 0.26 0.23 0.14 0.2 0.31 0.36 0.31 0.18 0.11 Na2O 3.9 4.34 4.71 4.17 4.1 4.5 4.43 4.88 4.7 Mo 1.09 0.48 0.64 0.45 0.66 1.2 1.12 1.33 15.6 TiO2 0.76 0.74 0.97 0.93 0.72 0.23 0.22 0.28 0.29 Sr 364 321 376 367 299 88.4 89.4 117 108 P2O5 0.14 0.13 0.24 0.19 0.13 0.03 0.03 0.04 0.04 Ba 499 533 386 396 599 696 718 736 934 MnO 0.15 0.12 0.17 0.18 0.13 0.04 0.05 0.04 0.04 V 238 216 264 301 225 7.89 7.16 10.3 12.4 LOI 1.86 1.5 1.54 1.63 1.59 0.61 0.65 0.72 0.76 Sc 31.9 27.6 26.7 25.2 25.5 5.83 5.72 7.05 6.23 H2O+ 0.95 0.71 0.94 0.81 0.83 0.45 0.41 0.48 0.45 Nb 5.57 6.73 4.9 5.54 5.83 11.1 10.5 10.1 9.25 Total 100.91 100.68 100.89 100.75 100.77 100.45 100.41 100.48 100.43 Ta 0.44 0.5 0.38 0.39 0.44 0.85 0.85 0.81 0.82 La 19.3 20.6 18.4 14.5 16.4 27.1 25.4 28.4 19.8 Zr 99.1 142 112 139 103 269 260 282 263 Ce 42.2 46.5 42.2 34.2 38.9 60.1 55.5 61.3 43.9 Hf 2.59 3.52 2.73 3.15 2.7 6.77 6.35 6.8 6.03 Pr 5.5 6 5.77 4.49 5.42 7.99 7.46 7.54 5.58 Ga 17.5 17.6 19.5 17.8 16.8 14.6 14.2 13.7 13.8 Nd 22 22.7 23.2 18.5 21.7 29.8 27.8 27.3 21.8 U 0.9 1.3 0.59 0.58 0.76 1.72 1.73 1.34 1.36 Sm 5.18 5.33 5.54 4.53 5.4 6.55 6.21 5.75 5.13 Th 3.2 3.53 2.61 2.36 3.24 7.86 7.87 7.78 6.56 Eu 1.44 1.47 1.73 1.41 1.36 0.96 0.98 1.26 1.13 σ 2.55 2.63 2.33 2.07 3.02 1.87 1.93 1.92 2.17 Gd 5.46 5.75 6.12 4.77 5.96 6.71 6.4 5.75 5.32 R1 1672 1668 1605 1742 1551 2615 2589 2504 2359 Tb 0.91 0.96 1 0.8 1.03 1.16 1.07 0.99 0.94 R2 1097 993 1036 1130 1021 355 360 393 391 Dy 5.63 5.94 6.09 5.02 6.5 7.18 6.77 6.63 5.96 (La/Yb)N 3.88 3.72 3.75 3.32 2.92 3.80 3.80 4.27 3.18 Ho 1.24 1.28 1.29 1.08 1.38 1.62 1.52 1.49 1.32 (La/Sm)N 0.83 0.95 0.70 0.71 1.11 2.07 2.07 1.82 2.06 Er 3.57 3.72 3.61 3.12 4.02 4.87 4.51 4.41 4.06 (Gd/Yb)N 53.70 43.11 54.95 58.86 37.09 10.43 10.21 14.19 14.69 Tm 0.54 0.59 0.55 0.48 0.62 0.76 0.72 0.72 0.65 A/CNK 0.84 0.84 0.88 0.83 0.87 1.04 1.02 1.01 1.02 Yb 3.57 3.97 3.52 3.13 4.03 5.12 4.8 4.77 4.46 Mg# 44.31 40.88 38.25 41.80 41.17 21.59 21.18 25.85 30.27 Lu 0.57 0.64 0.56 0.49 0.63 0.85 0.8 0.8 0.76 Rb/ Sr 0.11 0.11 0.03 0.04 0.10 0.65 0.74 0.38 0.45 Y 32.2 34.5 33.4 27.9 36.1 42.1 38.4 38.7 35.7 δEu 0.82 0.81 0.90 0.92 0.73 0.44 0.47 0.66 0.66 Cu 58.3 33.4 28.7 54.9 24.7 6.69 7.22 10.7 2.88 δCe 0.99 1.01 1.00 1.03 1.01 0.99 0.98 1.01 1.01 Pb 8.25 4.55 4.09 3.92 4.72 5.37 12.7 6.03 3.44 -
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