U-Pb detrital zircon geochronology of sedimentary rocks in NE Vietnam: Implication for Early and Middle Devonian Palaeogeography

56 4.8 0.05593 3.4 0.69 409 13 415 16 450 77 91 c29 23202 256 18 0.52 3053 0.06558 2.6 0.49731 3.7 0.05500 2.6 0.70 409 10 410 12 412 59 99 c44 22600 346 24 0.32 41651 0.06543 3.3 0.49856 3.9 0.05526 2.1 0.84 409 13 411 13 423 48 97 c40 15315 211 15 0.27 23688 0.06800 2.7 0.52195 3.1 0.05567 1.6 0.86 424 11 426 11 439 36 97 b47 8277 201 15 0.41 15205 0.06821 3.4 0.52255 4.8 0.05556 3.4 0.71 425 14 427 17 435 75 98 b19 32280 417 30 0.34 58044 0.06855 2.0 0.53418 2.2 0.05652 0.7 0.94 427 8 435 8 473 17 90 b43 6358 139 9 0.22 11572 0.06849 2.6 0.52605 4.0 0.05571 3.0 0.66 427 11 429 14 441 68 97 c12 37937 425 31 0.38 11655 0.06907 3.4 0.53109 4.2 0.05577 2.4 0.82 431 14 433 15 443 54 97 c16 22708 276 22 0.61 8586 0.06908 2.7 0.52934 3.2 0.05557 1.8 0.84 431 11 431 11 435 39 99 b40 12935 254 19 0.40 23523 0.06966 2.3 0.53686 3.2 0.05589 2.1 0.73 434 10 436 11 448 48 97 c21 69039 519 39 0.29 2504 0.06976 3.4 0.53813 3.6 0.05595 1.3 0.93 435 14 437 13 450 29 97 b50 20881 515 38 0.32 37772 0.07102 3.0 0.54981 3.9 0.05615 2.4 0.78 442 13 445 14 458 54 96 b58 7593 206 15 0.29 13759 0.07103 2.6 0.54943 3.3 0.05610 2.2 0.77 442 11 445 12 456 48 97 b41 8778 220 17 0.39 15780 0.07110 2.5 0.55319 3.4 0.05643 2.3 0.74 443 11 447 12 469 50 94 b45 11178 271 20 0.31 20379 0.07109 2.6 0.54665 3.9 0.05577 2.9 0.67 443 11 443 14 443 65 100 c39 18780 264 20 0.37 34158 0.07126 3.0 0.54912 3.7 0.05589 2.2 0.80 444 13 444 14 448 50 99 c17 8409 89 7 0.42 14831 0.07193 2.8 0.55701 3.4 0.05616 1.9 0.83 448 12 450 12 459 42 98 c33 35564 461 35 0.29 39095 0.07358 2.8 0.56936 3.3 0.05612 1.7 0.85 458 12 458 12 457 38 100 a6 18384 219 16 0.28 33020 0.07390 1.7 0.57568 2.0 0.05650 0.9 0.89 460 8 462 7 472 20 97 c32 26474 340 25 0.22 11354 0.07399 2.8 0.57467 3.6 0.05633 2.2 0.79 460 13 461 13 466 49 99 c14 17991 205 15 0.24 32363 0.07417 2.8 0.57761 3.3 0.05648 1.8 0.85 461 13 463 12 471 39 98 b32 9386 170 13 0.39 16769 0.07468 2.6 0.58238 5.7 0.05656 5.0 0.45 464 12 466 21 474 111 98   b55 8668 229 18 0.35 15611 0.07478 2.4 0.58142 3.4 0.05639 2.4 0.71 465 11 465 13 468 52 99 c31 16079 222 17 0.40 10133 0.07502 2.9 0.58516 3.5 0.05657 2.1 0.81 466 13 468 13 475 46 98 b3 13794 198 15 0.37 8281 0.07511 2.3 0.59127 3.2 0.05709 2.3 0.70 467 10 472 12 495 50 94 b54 12904 335 25 0.22 23308 0.07515 2.4 0.58437 3.7 0.05640 2.7 0.66 467 11 467 14 468 61 100 b53 7700 177 14 0.38 3912 0.07535 2.6 0.59396 6.2 0.05717 5.7 0.41 468 12 473 24 498 126 94 c18 7980 92 7 0.32 14136 0.07528 2.8 0.59613 3.4 0.05743 1.9 0.83 468 13 475 13 508 42 92 b33 4505 88 8 0.64 5576 0.07552 2.3 0.58862 4.4 0.05653 3.7 0.53 469 10 470 17 473 82 99 a7 7469 75 6 0.45 1460 0.07563 2.0 0.58978 4.4 0.05656 4.0 0.44 470 9 471 17 474 88 99 a8 20677 258 20 0.27 21145 0.07573 1.7 0.58984 3.1 0.05649 2.6 0.56 471 8 471 12 472 57 100 c50 17715 272 21 0.23 31793 0.07574 3.9 0.59216 4.6 0.05671 2.4 0.85 471 18 472 17 480 53 98 b42 9459 167 14 0.44 16780 0.07602 2.4 0.60004 3.5 0.05724 2.5 0.70 472 11 477 13 501 54 94 c11 13914 152 12 0.28 24983 0.07603 3.2 0.59195 3.8 0.05647 2.1 0.84 472 15 472 15 471 46 100 b28 13190 211 16 0.14 23567 0.07670 2.2 0.60179 2.8 0.05690 1.7 0.79 476 10 478 11 488 37 98 b30 12907 233 19 0.56 23149 0.07667 3.0 0.59948 4.5 0.05671 3.3 0.67 476 14 477 17 480 73 99 c22 8658 97 8 0.54 5150 0.07656 3.0 0.59700 4.7 0.05656 3.6 0.64 476 14 475 18 474 79 100 b51 4665 111 9 0.32 6216 0.07675 2.6 0.60730 5.2 0.05739 4.5 0.50 477 12 482 20 506 99 94 c1 7782 71 7 0.77 13797 0.07677 2.9 0.60455 4.3 0.05712 3.1 0.68 477 13 480 16 496 69 96 c23 19571 235 19 0.34 7623 0.07687 2.8 0.60308 3.3 0.05690 1.7 0.85 477 13 479 13 488 38 98 c30 7044 81 7 0.51 12602 0.07700 3.1 0.60483 4.8 0.05697 3.7 0.64 478 14 480 19 490 81 98 b15 4257 61 5 0.45 7590 0.07734 2.1 0.60858 3.6 0.05707 2.9 0.59 480 10 483 14 494 64 97 b18 8455 118 9 0.26 15195 0.07722 2.4 0.60663 13.6 0.05697 13.4 0.18 480 11 481 54 491 296 98 b21 23377 417 33 0.45 4376 0.07735 2.6 0.60594 3.3 0.05682 2.0 0.80 480 12 481 13 484 43 99 b57 3740 95 8 0.42 6639 0.07726 2.5 0.60918 4.7 0.05718 4.0 0.52 480 11 483 18 499 88 96 a1 7229 96 8 0.39 6827 0.07771 2.4 0.61336 3.0 0.05724 1.9 0.78 482 11 486 12 501 42 96 b27 11280 167 13 0.14 14484 0.07818 2.4 0.61805 3.3 0.05733 2.2 0.74 485 11 489 13 504 49 96 b10 9732 141 11 0.29 17282 0.07825 2.1 0.61611 5.1 0.05710 4.6 0.40 486 10 487 20 496 102 98 b5 10435 149 13 0.51 18609 0.07864 3.8 0.61854 5.0 0.05704 3.2 0.77 488 18 489 19 493 70 99 c45 7774 108 9 0.23 2456 0.07909 3.1 0.62292 3.7 0.05712 2.1 0.82 491 15 492 15 496 47 99   Königshof P., et al./Vietnam Journal of Earth Sciences 39 (2017) 312 b12 5919 85 7 0.29 10489 0.07941 2.6 0.62618 4.0 0.05719 3.0 0.66 493 12 494 16 499 67 99 c3 10098 95 9 0.57 17791 0.07968 3.0 0.63427 4.8 0.05773 3.7 0.64 494 14 499 19 520 81 95 c15 9115 89 8 0.39 16242 0.07969 3.2 0.62704 3.9 0.05707 2.2 0.82 494 15 494 15 494 49 100 b31 5610 103 9 0.45 9888 0.08042 2.7 0.63827 7.7 0.05756 7.3 0.34 499 13 501 31 513 160 97 b52 19621 391 38 0.53 18053 0.08712 3.3 0.70977 3.8 0.05909 1.8 0.88 538 17 545 16 570 39 94 c5 11309 119 12 0.87 440 0.09037 2.8 0.73995 6.0 0.05939 5.3 0.46 558 15 562 26 581 115 96 b1 4807 59 6 0.41 4464 0.09547 1.9 0.78555 9.8 0.05967 9.6 0.19 588 10 589 45 592 208 99 c4 10498 78 8 0.23 17639 0.09969 3.7 0.82948 4.6 0.06034 2.7 0.81 613 22 613 22 616 59 99 c37 15024 129 15 0.45 25045 0.10350 3.0 0.86903 3.6 0.06090 1.9 0.85 635 18 635 17 636 41 100 b36 6375 75 9 0.33 10406 0.11107 2.5 0.95219 4.3 0.06218 3.5 0.58 679 16 679 21 680 74 100 c10 37845 207 29 0.80 1413 0.11307 3.0 0.98677 4.0 0.06330 2.5 0.77 691 20 697 20 718 54 96 b60 8701 142 18 0.54 13798 0.11506 2.1 1.01722 4.1 0.06412 3.5 0.52 702 14 713 21 746 74 94 b49 7030 79 13 1.21 11232 0.11702 2.9 1.02113 4.7 0.06329 3.7 0.62 713 20 714 24 718 78 99 b26 7123 57 10 0.96 11087 0.12363 4.7 1.11078 7.4 0.06516 5.7 0.63 751 33 759 40 780 121 96 a3 19269 106 13 0.35 29298 0.12549 2.1 1.15922 2.9 0.06700 2.0 0.72 762 15 782 16 838 42 91 c38 15308 122 19 0.50 16917 0.14109 2.8 1.31767 4.0 0.06773 2.8 0.71 851 23 853 23 860 58 99 b24 14347 110 20 0.96 21315 0.14379 2.3 1.35643 2.8 0.06842 1.5 0.83 866 19 870 16 881 32 98 c35 24908 136 21 0.31 10028 0.14713 3.2 1.41194 4.1 0.06960 2.6 0.78 885 26 894 25 917 53 97 b2 15212 77 13 0.47 22034 0.15056 3.0 1.45627 3.8 0.07015 2.4 0.77 904 25 912 23 933 50 97 b29 6277 35 7 1.03 9050 0.15388 2.8 1.49229 5.6 0.07034 4.8 0.51 923 24 927 35 938 99 98 c8 25655 107 20 0.52 36359 0.16094 2.8 1.59844 3.3 0.07203 1.7 0.85 962 25 970 21 987 35 97 b22 40883 407 62 0.15 56775 0.16114 2.6 1.63117 3.9 0.07342 2.9 0.67 963 23 982 25 1026 58 94 b11 84172 478 80 0.32 21121 0.16130 2.8 1.59912 3.2 0.07190 1.6 0.87 964 25 970 20 983 32 98 c47 91234 490 79 0.25 6219 0.16220 2.6 1.60812 3.2 0.07191 1.9 0.80 969 23 973 20 983 39 99 b8 35027 169 30 0.41 49368 0.16247 2.2 1.61489 2.7 0.07209 1.6 0.82 971 20 976 17 988 32 98 c13 57925 221 40 0.43 81587 0.16594 2.8 1.65029 3.1 0.07213 1.4 0.89 990 25 990 20 990 29 100 c34 34857 156 30 0.49 18600 0.17380 3.2 1.79069 4.0 0.07473 2.3 0.81 1033 31 1042 26 1061 47 97 b16 11254 48 11 0.96 15409 0.17657 2.4 1.80454 3.8 0.07412 2.9 0.64 1048 24 1047 25 1045 59 100   b9 24566 110 21 0.44 33687 0.17664 2.2 1.80499 2.7 0.07411 1.6 0.81 1049 22 1047 18 1044 32 100 c2 31933 108 19 0.15 43805 0.18029 2.7 1.84170 3.0 0.07409 1.4 0.88 1069 26 1060 20 1044 29 102 c48 50730 247 49 0.39 68274 0.18034 2.9 1.87705 3.2 0.07549 1.3 0.92 1069 29 1073 21 1082 26 99 c24 126515 470 82 0.12 30177 0.18181 2.6 1.88881 2.9 0.07535 1.2 0.91 1077 26 1077 19 1078 24 100 b46 10415 80 18 0.82 13965 0.18213 2.2 1.90864 3.5 0.07600 2.7 0.63 1079 22 1084 23 1095 54 98 b34 5868 37 7 0.63 7352 0.18453 2.6 1.99016 7.6 0.07822 7.1 0.34 1092 26 1112 53 1152 142 95 c20 30855 94 22 0.83 40148 0.18489 2.9 1.98970 3.9 0.07805 2.5 0.76 1094 30 1112 26 1148 50 95 b14 27313 114 23 0.43 36441 0.18544 2.4 1.94603 3.3 0.07611 2.2 0.74 1097 24 1097 22 1098 44 100 c42 80693 327 73 0.63 5567 0.18579 2.8 1.97393 3.4 0.07706 2.0 0.82 1099 29 1107 23 1123 39 98 b25 3178 17 3 0.31 4008 0.18884 2.5 2.07322 11.9 0.07963 11.6 0.21 1115 25 1140 85 1188 229 94 a4 23696 69 18 1.17 30918 0.19384 2.4 2.07776 3.2 0.07774 2.0 0.77 1142 25 1141 22 1140 40 100 c41 14156 50 13 0.88 18000 0.20036 4.4 2.20762 4.8 0.07991 2.0 0.91 1177 47 1183 34 1195 39 99 c19 41031 106 28 0.84 51886 0.20227 3.2 2.23365 3.7 0.08009 1.9 0.86 1187 35 1192 26 1199 38 99 b17 24945 70 20 0.72 15755 0.23802 2.4 2.87190 3.0 0.08751 1.8 0.79 1376 30 1375 23 1372 35 100 c28 139381 389 107 0.54 8792 0.24815 2.7 3.09497 3.1 0.09046 1.5 0.87 1429 35 1431 24 1435 29 100 b39 10398 35 14 1.69 11350 0.25251 2.8 3.23544 3.7 0.09293 2.4 0.75 1451 36 1466 29 1486 46 98 c36 98148 211 61 0.83 4771 0.27020 3.3 3.67386 3.8 0.09861 1.9 0.87 1542 45 1566 31 1598 35 96 b44 20776 68 23 1.03 4467 0.28452 2.2 3.97263 2.6 0.10127 1.5 0.82 1614 31 1629 22 1647 28 98 c46 165247 331 104 0.34 37977 0.29087 3.5 4.06053 4.2 0.10125 2.4 0.83 1646 51 1646 35 1647 44 100 c9 31121 42 14 0.37 30876 0.29370 2.6 4.14834 3.5 0.10244 2.4 0.74 1660 38 1664 29 1669 44 99 b35 17232 42 15 0.67 16555 0.30133 2.7 4.38985 3.2 0.10566 1.7 0.84 1698 40 1710 27 1726 32 98 b23 51782 104 33 0.17 49762 0.31690 2.3 4.62523 40.1 0.10585 40.0 0.06 1775 36 1754 406 1729 734 103 c7 164253 208 76 0.41 146745 0.32323 3.3 5.06962 3.5 0.11375 1.1 0.95 1805 52 1831 30 1860 20 97 b56 121788 207 113 0.56 77982 0.45765 3.1 10.01660 3.3 0.15874 1.2 0.93 2429 63 2436 31 2442 21 99 c6 360239 234 135 0.83 225570 0.47007 2.6 10.52845 2.9 0.16244 1.3 0.90 2484 55 2482 28 2481 22 100 c43 238053 184 112 0.67 138532 0.47496 2.5 11.45528 4.5 0.17492 3.7 0.57 2505 53 2561 42 2605 61 96 b4 113652 81 46 0.53 31352 0.47527 2.3 10.97481 2.6 0.16748 1.2 0.88 2507 47 2521 24 2533 20 99 c49 168836 50 48 0.73 59281 0.69227 4.0 27.59714 4.2 0.28913 1.2 0.96 3391 107 3405 42 3413 18 99   awithin-run background-corrected mean 207Pb signal in counts per second; bU and Pb content and Th/U ratio were calculated relative to GJ-1 and are accurate to approximately 10%; ccorrected for background, mass bias, laser induced U-Pb fractionation and common Pb (if detecta- ble, see analytical method) using Stacey & Kramers (1975) model Pb composition. 207Pb/235U calculated using 207Pb/206Pb/(238U/206Pb × 1/137.88). Errors are propagated by quadratic addition of within-run errors (2SE) and the reproducibility of GJ-1 (2SD); dRho is the error correlation defined as err206Pb/238U/err207Pb/235 Vietnam Journal of Earth Sciences, 39(4), 303-323 313 Table 2. Zircon U-Pb analytical data of sample VN24, n = 96 of 120 measured zircon grains, sandstone (Do Son group, Van Canh Formation, Early Devonian; location: Do Son Peninsula, Vietnam: (N20°42’36,1’’; E106°47’02,4’’) Number 207Pba (cps) Ub (ppm) Pbb (ppm) Thb U 206Pbc 204Pb 206Pbc 238U 2  % 207Pbc 235U 2  % 207Pbc 206Pb 2  % rho d 206Pb 238U 2  (Ma) 207Pb 235U 2  (Ma) 207Pb 206Pb 2  (Ma) conc % a26 5134 123 8 0.35 9504 0.06505 3.6 0.49377 4.7 0.05506 3.0 0.78 406 14 407 16 414 66 98 c7 25486 516 34 0.31 15818 0.06507 2.5 0.50589 4.0 0.05639 3.2 0.62 406 10 416 14 468 70 87 a17 23382 495 34 0.28 43515 0.06525 5.1 0.49373 6.4 0.05488 3.8 0.80 407 20 407 22 407 85 100 a50 5331 189 15 0.71 9913 0.06528 4.4 0.49408 5.5 0.05489 3.3 0.80 408 17 408 19 408 74 100 b39 14431 240 17 0.27 26365 0.06666 2.2 0.51046 4.5 0.05554 3.9 0.49 416 9 419 15 434 87 96 d8 25755 398 28 0.34 29892 0.06665 2.8 0.51232 3.8 0.05575 2.6 0.74 416 11 420 13 442 57 94 c1 10823 161 13 0.68 19834 0.06731 3.5 0.51596 4.0 0.05560 2.0 0.87 420 14 422 14 436 44 96 b22 36912 594 44 0.39 67828 0.06754 4.3 0.51706 5.9 0.05552 4.0 0.74 421 18 423 20 433 88 97 b43 617 10 1 0.45 599 0.06751 3.8 0.88699 12.4 0.09529 11.8 0.30 421 15 645 61 1534 222 27 a59 13789 588 39 0.16 25434 0.06766 4.8 0.51513 6.0 0.05522 3.5 0.80 422 20 422 21 421 79 100 d12 13379 221 16 0.39 24506 0.06766 4.5 0.52096 5.1 0.05584 2.3 0.89 422 18 426 18 446 52 95 b11 10601 126 9 0.40 19354 0.06790 2.6 0.51952 4.1 0.05549 3.2 0.63 423 11 425 14 432 71 98 a20 22106 436 32 0.39 40584 0.06891 3.3 0.52782 3.8 0.05555 2.0 0.86 430 14 430 13 434 44 99 a19 9977 185 14 0.43 18281 0.07007 3.6 0.54069 4.5 0.05597 2.7 0.80 437 15 439 16 451 61 97 a37 8942 179 14 0.47 7871 0.07012 3.4 0.54063 4.7 0.05592 3.2 0.73 437 15 439 17 449 71 97 a10 8503 127 9 0.25 15438 0.07033 3.3 0.54447 3.9 0.05615 2.2 0.84 438 14 441 14 458 48 96 a14 10688 191 14 0.38 19592 0.07023 3.5 0.53900 4.3 0.05566 2.4 0.82 438 15 438 15 439 54 100 d4 24771 387 28 0.30 22295 0.07052 3.4 0.54416 4.6 0.05597 3.0 0.75 439 15 441 17 451 67 97 a22 6940 141 11 0.43 12602 0.07100 3.5 0.55042 6.1 0.05622 4.9 0.58 442 15 445 22 461 109 96 a11 8175 134 10 0.28 14752 0.07111 3.7 0.55212 4.9 0.05631 3.2 0.76 443 16 446 18 465 70 95 b27 28401 430 33 0.40 14515 0.07178 3.9 0.55395 4.4 0.05597 2.1 0.88 447 17 448 16 451 46 99 b16 16855 236 18 0.39 30312 0.07243 3.4 0.56185 4.2 0.05626 2.5 0.81 451 15 453 15 463 55 97 a53 7232 238 20 0.50 1822 0.07377 4.2 0.63509 12.2 0.06244 11.4 0.35 459 19 499 49 689 243 67 b33 14105 235 19 0.50 8039 0.07403 3.6 0.57400 5.9 0.05623 4.7 0.60 460 16 461 22 462 105 100 a32 15457 360 27 0.27 28066 0.07419 3.4 0.57497 3.9 0.05621 1.9 0.87 461 15 461 15 461 42 100   b24 14081 163 13 0.47 9300 0.07436 2.3 0.58027 3.4 0.05660 2.5 0.69 462 10 465 13 476 55 97 b18 11121 171 14 0.36 19698 0.07471 4.2 0.58977 5.2 0.05726 3.0 0.82 464 19 471 20 501 66 93 c4 15969 252 19 0.16 2778 0.07487 3.6 0.58613 4.6 0.05678 2.9 0.78 465 16 468 17 483 64 96 b14 10380 141 11 0.36 18635 0.07588 2.7 0.59076 3.6 0.05647 2.3 0.76 471 12 471 14 471 51 100 a25 26312 453 35 0.30 28811 0.07603 7.4 0.59349 8.9 0.05662 5.0 0.83 472 34 473 34 477 110 99 a57 4447 170 13 0.30 7873 0.07676 4.3 0.60799 6.5 0.05745 4.8 0.67 477 20 482 25 509 106 94 d3 20465 310 23 0.20 36690 0.07701 3.0 0.60701 5.1 0.05717 4.1 0.59 478 14 482 20 498 90 96 a36 12549 310 26 0.50 22497 0.07709 3.3 0.60378 3.8 0.05681 2.0 0.86 479 15 480 15 484 43 99 b28 13514 201 16 0.29 24497 0.07713 3.2 0.60542 4.3 0.05693 2.9 0.73 479 15 481 17 489 65 98 a42 3943 113 10 0.48 7063 0.07813 3.4 0.61363 3.9 0.05696 1.8 0.88 485 16 486 15 490 40 99 a23 7012 124 12 0.55 12530 0.07840 3.6 0.61789 6.1 0.05716 5.0 0.58 487 17 489 24 498 110 98 b29 21129 312 26 0.35 37620 0.07869 4.4 0.61879 5.2 0.05703 2.8 0.85 488 21 489 20 493 61 99 b53 228 4 0 0.19 135 0.07866 3.8 0.89960 34.9 0.08295 34.7 0.11 488 18 652 183 1268 677 38 a45 3440 122 10 0.38 6227 0.07892 3.5 0.61297 4.6 0.05633 2.9 0.77 490 17 485 18 465 64 105 b32 9019 136 13 0.66 5605 0.07899 2.5 0.62454 4.3 0.05734 3.5 0.59 490 12 493 17 505 76 97 a41 4250 112 10 0.55 7757 0.08026 3.4 0.62409 5.4 0.05640 4.2 0.63 498 16 492 21 468 93 106 b19 8463 101 9 0.32 13439 0.08546 2.4 0.69530 3.6 0.05900 2.6 0.69 529 12 536 15 567 57 93 a29 4416 77 7 0.32 7735 0.08568 4.6 0.68706 5.5 0.05816 2.9 0.84 530 23 531 23 536 65 99 a47 5028 155 14 0.55 4440 0.08715 3.9 0.70149 5.3 0.05838 3.6 0.73 539 20 540 22 544 79 99 b35 9014 118 12 0.63 4351 0.08775 1.8 0.70648 4.5 0.05839 4.1 0.41 542 10 543 19 544 89 100 b40 20438 281 28 0.56 35537 0.08765 3.2 0.70541 4.0 0.05837 2.5 0.79 542 16 542 17 544 54 100 b30 16506 184 17 0.26 27820 0.09184 3.1 0.75172 3.7 0.05937 2.0 0.84 566 17 569 16 581 44 98 a33 4767 74 9 0.73 7972 0.10129 4.0 0.85068 5.7 0.06091 4.0 0.71 622 24 625 27 636 87 98 d1 6009 51 6 0.37 10101 0.10170 3.4 0.85786 4.6 0.06118 3.1 0.74 624 20 629 22 646 67 97 b13 31450 268 33 0.20 50044 0.11261 6.0 0.98981 7.2 0.06375 4.1 0.83 688 39 699 37 733 86 94 a18 10380 93 12 0.44 16526 0.11696 4.1 1.03021 4.7 0.06388 2.4 0.86 713 28 719 25 738 51 97 b21 14283 116 14 0.33 17920 0.11773 1.6 1.03809 4.7 0.06395 4.4 0.35 717 11 723 24 740 93 97 b23 12556 91 11 0.27 4710 0.11917 2.8 1.04542 3.6 0.06362 2.2 0.78 726 19 727 19 729 47 100   Königshof P., et al./Vietnam Journal of Earth Sciences 39 (2017) 314 a56 9053 162 22 0.46 14430 0.11999 5.5 1.06150 7.4 0.06416 4.9 0.75 731 38 735 39 747 104 98 b12 8552 59 11 1.24 6977 0.12009 4.5 1.06850 6.5 0.06453 4.6 0.70 731 31 738 35 759 97 96 b2 15756 93 14 0.61 24510 0.12899 4.8 1.15841 5.4 0.06513 2.3 0.90 782 36 781 30 779 49 100 b36 9116 67 12 0.91 13827 0.13292 3.7 1.22574 4.8 0.06688 3.0 0.78 804 28 812 27 834 62 96 a46 18542 260 37 0.33 28770 0.13300 4.0 1.21017 5.1 0.06599 3.2 0.77 805 30 805 29 806 68 100 b7 10001 47 7 0.39 15175 0.13337 2.9 1.23248 4.0 0.06702 2.8 0.72 807 22 815 23 839 58 96 a38 25092 282 40 0.29 23507 0.13626 3.7 1.24895 4.1 0.06648 1.7 0.90 823 29 823 23 821 36 100 a27 36007 261 40 0.44 512 0.13749 4.1 1.27060 8.5 0.06703 7.4 0.48 830 32 833 49 839 155 99 a24 7875 70 10 0.40 11928 0.14028 3.6 1.30216 4.2 0.06732 2.2 0.86 846 29 847 25 848 46 100 a21 29205 231 34 0.33 43921 0.14131 3.7 1.32286 4.8 0.06790 3.0 0.77 852 29 856 28 865 63 98 b26 55573 353 55 0.44 83483 0.14124 2.7 1.31417 3.2 0.06748 1.8 0.83 852 21 852 19 853 38 100 a1 6179 33 7 1.12 8883 0.15300 3.4 1.49751 4.0 0.07098 2.1 0.84 918 29 929 25 957 44 96 a7 8266 37 7 0.81 11796 0.15456 5.1 1.52638 6.0 0.07162 3.2 0.84 926 44 941 38 975 66 95 b37 40415 268 43 0.30 21301 0.15765 3.8 1.57489 4.4 0.07245 2.2 0.86 944 33 960 28 999 45 95 a9 32654 173 30 0.45 47026 0.15853 3.4 1.54991 3.9 0.07091 1.9 0.87 949 30 950 24 955 38 99 a6 21096 101 19 0.63 29839 0.15876 3.7 1.57960 4.1 0.07216 1.8 0.90 950 33 962 26 991 36 96 b31 79765 428 76 0.44 112030 0.15955 3.8 1.58789 4.9 0.07218 3.1 0.77 954 34 965 31 991 64 96 a30 7001 52 13 1.57 9986 0.16149 3.5 1.59404 4.8 0.07159 3.3 0.73 965 32 968 31 974 68 99 a60 8359 132 20 0.09 6149 0.16249 3.1 1.60905 4.4 0.07182 3.2 0.69 971 28 974 28 981 65 99 a34 34879 432 66 0.06 5849 0.16330 4.7 1.64701 5.3 0.07315 2.6 0.88 975 42 988 34 1018 52 96 a2 104468 618 107 0.33 11909 0.16678 3.9 1.74540 4.8 0.07590 2.7 0.82 994 36 1025 31 1092 55 91 b6 22976 100 19 0.44 30886 0.16802 3.3 1.68216 4.1 0.07261 2.4 0.81 1001 31 1002 27 1003 50 100 d5 38954 171 31 0.36 3626 0.16854 3.0 1.69451 3.7 0.07292 2.3 0.79 1004 28 1006 24 1012 46 99 b10 44446 222 39 0.26 60280 0.16898 1.7 1.74359 3.5 0.07483 3.1 0.47 1007 16 1025 23 1064 63 95 a40 21336 214 37 0.27 29623 0.16995 3.0 1.72087 3.3 0.07344 1.3 0.91 1012 28 1016 21 1026 27 99 b38 19865 84 17 0.65 27801 0.17026 1.6 1.69615 3.7 0.07225 3.3 0.45 1014 15 1007 24 993 67 102 a55 57055 848 143 0.13 13945 0.17083 6.5 1.77232 8.8 0.07524 5.9 0.74 1017 62 1035 59 1075 118 95 b4 24293 118 21 0.27 32739 0.17461 5.9 1.78522 6.9 0.07415 3.6 0.85 1037 57 1040 46 1046 73 99  a44 5124 49 12 1.16 6759 0.17495 4.7 1.86469 5.1 0.07730 1.9 0.92 1039 45 1069 34 1129 39 92 b17 76436 356 60 0.08 57563 0.17656 3.0 1.82790 3.5 0.07509 1.7 0.86 1048 29 1056 23 1071 35 98 a28 81832 567 97 0.06 109701 0.17973 3.4 1.87765 4.5 0.07577 3.0 0.75 1066 33 1073 30 1089 60 98 c2 71217 398 72 0.19 4716 0.18156 3.1 1.95170 13.3 0.07796 12.9 0.23 1076 30 1099 93 1146 256 94 a16 41484 216 44 0.47 52644 0.18455 2.9 2.04743 5.2 0.08046 4.4 0.55 1092 29 1131 36 1208 86 90 a48 15535 146 29 0.25 11676 0.19060 3.8 2.10031 5.3 0.07992 3.7 0.73 1125 40 1149 37 1195 72 94 d7 65941 292 61 0.46 86911 0.19191 2.4 2.05778 3.1 0.07777 2.0 0.78 1132 25 1135 21 1141 39 99 b1 36807 129 26 0.27 46715 0.19236 2.5 2.09797 5.4 0.07910 4.8 0.45 1134 26 1148 38 1175 96 97 a31 60330 472 99 0.39 77591 0.19822 3.1 2.17485 3.5 0.07958 1.7 0.87 1166 33 1173 25 1186 34 98 a3 32497 122 28 0.47 41166 0.20461 3.5 2.26842 3.9 0.08041 1.7 0.90 1200 38 1203 28 1207 34 99 b20 72276 703 137 0.01 6644 0.20703 1.6 2.42291 8.9 0.08488 8.8 0.18 1213 18 1249 66 1313 170 92 a39 34447 208 46 0.25 42863 0.20922 3.8 2.36523 4.3 0.08199 2.0 0.88 1225 42 1232 31 1245 39 98 a5 104195 383 89 0.40 20818 0.21036 4.6 2.37808 4.9 0.08199 1.6 0.95 1231 52 1236 35 1245 31 99 a8 40168 137 34 0.48 48411 0.22342 3.9 2.61042 4.3 0.08474 1.7 0.91 1300 46 1304 32 1310 34 99 c6 100953 277 74 0.40 112644 0.24417 2.7 3.07637 3.0 0.09138 1.4 0.89 1408 34 1427 23 1454 26 97 b25 42053 96 30 0.56 44505 0.26914 2.3 3.55415 3.0 0.09578 2.0 0.76 1536 32 1539 24 1543 37 100 a15 21301 49 15 0.49 22266 0.27602 6.0 3.71575 6.4 0.09763 2.2 0.94 1571 85 1575 53 1579 42 99 d10 67455 140 45 0.60 21523 0.27857 2.1 3.90814 2.5 0.10175 1.3 0.86 1584 30 1615 20 1656 23 96 d11 67124 140 45 0.61 26819 0.27941 2.3 3.92210 2.6 0.10181 1.2 0.88 1588 32 1618 21 1657 23 96 a54 52720 313 102 0.49 53234 0.28302 3.9 3.94019 4.3 0.10097 1.7 0.92 1607 56 1622 35 1642 32 98 a4 97940 201 63 0.31 96102 0.29719 3.3 4.24251 3.6 0.10353 1.4 0.92 1677 49 1682 30 1688 26 99 b34 60089 104 37 0.34 23953 0.32196 3.5 4.95868 4.2 0.11170 2.3 0.84 1799 56 1812 36 1827 41 98 a58 81843 325 127 0.29 68373 0.36264 4.3 6.10709 4.8 0.12214 2.1 0.90 1995 75 1991 43 1988 37 100 a51 99017 296 146 0.56 27901 0.42433 3.4 9.05001 4.3 0.15469 2.5 0.81 2280 66 2343 40 2398 43 95 a35 170185 299 169 0.80 108202 0.44599 4.5 9.86129 4.9 0.16037 2.0 0.91 2377 89 2422 46 2460 35 97 a49 215623 421 222 0.36 136660 0.46354 3.4 10.31402 4.5 0.16138 3.0 0.75 2455 69 2463 43 2470 50 99 b3 280638 165 87 0.36 165754 0.46549 1.7 10.95972 6.6 0.17076 6.4 0.26 2464 36 2520 64 2565 107 96 a13 189127 166 83 0.09 112803 0.47614 3.4 11.22270 3.5 0.17095 1.0 0.96 2510 70 2542 33 2567 17 98 a52 61345 113 61 0.28 35983 0.48023 4.2 11.52951 5.6 0.17413 3.7 0.76 2528 89 2567 54 2598 61 97 b8 110427 68 42 0.54 63532 0.49850 3.0 12.13716 3.4 0.17658 1.6 0.88 2607 64 2615 32 2621 26 99   awithin-run background-corrected mean 207Pb signal in counts per second; bU and Pb content and Th/U ratio were calculated relative to GJ-1 and are accurate to approximately 10%; ccorrected for background, mass bias, laser induced U-Pb fractionation and common Pb (if detectable, see analytical method) using Stacey & Kramers (1975) model Pb composition. 207Pb/235U calculated using 207Pb/206Pb/(238U/206Pb × 1/137.88). Errors are propagated by quadratic addition of within-run errors (2SE) and the reproducibility of GJ-1 (2SD); dRho is the error correlation defined as err206Pb/238U/err207Pb/235 Vietnam Journal of Earth Sciences, 39(4), 303-323 315 Table 3. Age ranges and percentage of detrital zircons in the samples VN23 (Van Huong Formation) and VN24 (Van Canh Formation). The 207Pb/206Pb age was taken for interpretation for all zircons >1.0 Ga, and the 206Pb/238U ages for younger grains. The applied stratigraphic time scale is based on data published in Ogg et al. (2016) Range(Ma) VN23 (%) VN24 (%) Lower Devonian 393-419 4.6 4.7 Silurian 419-444 12 11.3 Ordovician 444-485 28.9 12.3 Cambrian 485-541 7.4 8.5 Neoproterozoic 541-1000 19.4 28.2 Mesoproterozoic 1000-1600 17.6 24.5 Palaeoproterozoic 1600-2500 7.4 7.5 Archaean 2500-4000 2.7 2.8 Concordia plots and concordia age of the youngest zircon population of detrital zircons of sample VN23 and VN24 are displayed in Figures 6 and 7. All analysis of the zircons are concordant with a range from the Archean (~2500 Ma) to Palaeozoic (~400 Ma) in both samples. The age distribution of zircon grains in sample VN24 from the Van Canh Formation is more complex with multiple age peaks com- pared to those in sample VN23 from the Van Huong Formation. The largest group of zir- cons in sample VN24 belong to the Palaeozo- ic age, ranging from 541 Ma to 393 Ma (36,8%, Table 1). The main peaks in the prob- ability plot occur at 437 Ma and 476 Ma, which are flanked by a minor peak at 537 Ma. Neoproterozoic zircons with age ranging from 541 Ma to 1000 Ma represent the second largest group with 28.2%, followed by Meso- proterozoic zircons with age ranging from 1000 Ma to 1600 Ma (24.5%). The main peaks of Neoproterozoic zircon grains lie at ~720 Ma and ~810 Ma. A large peak of Mesoproterozoic zircon grains is found at ~1020 Ma. 7.5% of the zircon population from sample VN24 show a Palaeoproterozoic age (Table 3) with distinct peaks at ~1580 Ma and 2450 Ma (Figure 8). A few zircons (2.8%) yield the Archaean age (Table 3). Figure 6. Concordia plots and concordia age of the youngest zircon population of detrital zircon of sample VN23 Königshof P., et al./Vietnam Journal of Earth Sciences 39 (2017) 316 Figure 7. Concordia plots and concordia age of the youngest zircon population of detrital zircon of sample VN24  The age spectrum of zircon grains in sample VN23 from the Van Huong Formation is com- parable to that of sample VN24, but also exhibits some differences. The sample shows a large number of Palaeozoic zircon grains (53%, Table 3) with a concentration of Ordovician grains (28.9 %) and a pronounced peak at ~475 Ma. Neoproterozoic zircons are represented by 19.4% of all measured grains, in contrast to 28.2% in sample VN24 from the Van Canh Formation. Generally, Neoproterozoic zircon grains are evenly distributed (Table 3), but show a larger peak at ~963 Ma. The number of Mesoproterozoic zircon grains in sample VN23 (17.6%) also differs from that of sample VN24 (24.5%). Mesoproterozoic zircons exhibit a peak at ~1087 Ma but this peak is less promi- nent in comparison to that at ~1020 Ma in the sample VN24 (Figures 8, 9). The percentage distribution of zircon grains with Palaeoprote- rozoic and Archean ages of both samples are quite similar, having a peak at ~2500 Ma, but sample VN23 exhibits a major gap in age in the Palaeoproterozoic (Figure 9). Figure 8. Probability diagram of U-Pb ages of detrital zircons from sample VN24 (Silurian(?) to Early Devonian Van Canh Formation) Vietnam Journal of Earth Sciences, 39(4), 303-323 317 Figure 9. Probability diagram of U-Pb ages of detrital zircons from sample VN23 (Middle Devonian Van Huong Formation) 5. Discussion U-Pb ages of detrital zircons from the in- vestigated Van Canh Formation (sample VN24) of the Do Son Peninsula reflect two main episodes of crustal recycling, at ~407- 480 Ma and ~940-1100 Ma, with minor peaks at ~537 Ma, ~720 Ma, ~812 Ma, ~1600 Ma, and ~2500 Ma (Figure 5). In northwestern Vietnam detrital zircon U-Pb ages from rocks of the Sin Quyen Formation exhibit major age peaks in the Neoarchean (2.7-2.0 Ga and 2.2- 2.5 Ga.) as well as in the Palaeoproterozoic (~1.8 Ga.; Hieu et al., 2012, see also Mydung et al., 2014). Similar zircon age patterns from rocks of the Ca Vinh Complex are published in Nam et al. (2003). Palaeoproterozoic zircon ages are known from the Phan Si Pan Zone in northern Vietnam. Anh et al. (2015) report U- Pb ages for the Deo Khe Granitoids ranging from 1855-1873 Ma, which are similar to zir- con ages of 1.85 Ga reported from the Yangze Block in South China (Zhao and Cawood, 2012). Intrusive bodies which indicate the exist- ence of a Caledonian tectonothermal event in Vietnam are widely distributed. Based on ge- ochronological U-Pb and 40Ar-39Ar data pub- lished by Nagy et al. (2001) and Vu Van Tich (2001), this event was recognized in the Kon- tum Massif in central Vietnam, were magmat- ic rocks exhibit U-Pb ages ranging from 450 Ma to 424 Ma. Recently, Hieu et al. (2016) published zircon age dates of ~430 Ma from the Dai Loc granitoid complex, Kontum Mas- sif. Middle Palaeozoic U-Pb ages of intrusive rocks are also reported from the Thien Ke granite pluton in the Tam Dao region (Nguyen et al., 2014) and the Song Chay area (Roger et al., 2000; Yan et al., 2006). Relative probability plots for zircon ages of the Van Canh Formation (sample VN24, Figure 8) are similar to those from samples collected from the NE Vietnam Terrane which have major peaks at ~440 Ma, ~944 Ma and ~980 Ma and a minor peak at ~2400 Ma, as well as samples from the Ailaoshan Terrane, in southern China (Burrett et al., 2014; see Figure 10). According to these authors, the zircon peak of 800 Ma (Sibao orogeny) is weakly developed in NE Vietnam. This peak was less prominent in the sample of the Van Canh Formation (sample VN24; Figures 8, 10) and is absent in the overlying Van Huong Formation (sample VN23), as shown in Fig- ures 8-10, thus confirming the results pub- lished of Burrett et al. (2014). In South Cathaysia, detrital zircons exhibit a wide age spectrum, but it is important to note that they also cluster in two age peaks, at ~970 Ma and at ~2500 Ma (Yu et al., 2009) which is similar to the zircon spectrum presented in our study. Königshof P., et al./Vietnam Journal of Earth Sciences 39 (2017) 318 Figure 10. Relative probability plots of terranes and areas discussed in this study: Number (1) Ailaoshan Terrane (southern China), (2) Tethyan Himalaya, (3) Cathaysia Terrane (4) NE Vietnam from Burrett et al. (2014), (5) Van Canh Formation, Do Son Peninsula, Vietnam (this study), (6) Van Huong Formation, Do Son Peninsula, Vietnam (this study) Vietnam Journal of Earth Sciences, 39(4), 303-323 319 Zhu et al. (2011) reported that the presence or absence of younger (~950 Ma) or older Grenvillian (~1170 Ma) detrital zircons can be used to discriminate whether the blocks are derived from Indian or Australian margins. Whereas the younger Grenvillian zircons orig- inated from the Tethyan Himalaya, the older Grenvillian zircons are derived from the Al- bany-Fraser belt in southwestern Australia (Zhu et al., 2011). The presence of younger Grenvillian zircons in the Van Canh For- mation (VN24) supports the postulated posi- tion of NE Vietnam close to the western Himalaya. A few 2280-2377 Ma zircon grains are characterized by pale rims depleted in uranium, which were derived from rocks that underwent high pressure metamorphic condi- tions. Himalayan Palaeoproterozoic rocks could be the source area and angular to-well- rounded zircons in our samples suggest at least moderate transport distances. U-Pb ages of detrital zircons from the Middle Devonian Van Huong Formation show a major peak at ~406-475 Ma and smaller peaks at ~963 Ma, ~1087 Ma, and a small Palaeoproterozoic input at ~2500 Ma. The latter peak is also known from sample VN24 (Figures 8, 9). A possible source for this zircon peak may be associated with the Wutai orogeny, an event that is also known in the Tethyan Himalaya, Cathaysia, India, and Africa (Yu et al., 2009; Condie et al., 2009; Wan et al., 2011; Burrett et al., 2014). According to Squire et al. (2006), the den- udation of highlands that were formed during the Pan African and older orogenies were re- sponsible for the detrital sediment transport across Gondwana. The age spectrum of zircon grains in sample VN24 (Lower Devonian Van Canh Formation) exhibits Neoproterozoic, Mesoproterozoic, and Palaeoproterozoic zir- con grains whereas the overlying sample VN23 (Middle Devonian Van Huong For- mation) shows a major gap in the Palaeoprote- rozoic record (Figures 9, 10). This might be a result of reduced denudation, changing fluvial flow directions and/or slightly changing pal- aeogeographic position of northeast Vietnam. The youngest zircon of each formation provides maximum ages of sedimentation at 407.1 ± 9.5 Ma and 406.3 ± 4.0 Ma, which are in general agreement with the palaeontologi- cal data from the Middle Devonian Van Huong and the Early Devonian Van Canh Formations. Facies development and faunal similarities can also provide constraints on the palaeogeographic position of NE Vietnam. According to Xun et al. (1996), Lower Devo- nian sediments adjacent to the Huanan Land- mass are characterized by a wide range of shallow-water to alluvial facies settings. Simi- lar facies settings are known from northeast Vietnam. The assumed palaeogeographic po- sition of NE Vietnam in the Early and Middle Devonian close to the western Himalayas is most likely due to faunal similarities between Vietnam and southern China (Janvier and Ta Hoa, 1999; Janvier and Tong-Dzuy, 1988; Jones et al. 1997). Based on vertebrates, os- tracods, and brachiopods there is likely a pal- aeobiogeographic relation between the East Red River region in Vietnam and southern China. Racheboeuf et al. (2005) describe bey- richiids and leperditids from NE Vietnam (Ha Giang Province) which closely resembles forms from the Silurian and Devonian of the Yunnan Province of South China. Further- more, the vertebrate fauna of NE Vietnam and South China is also similar (Janvier and Ta Hoa, 1999). The Silurian part of the Do Son Group (lower part of the Van Canh Formation) on the Do Son Island contains fish remains which can be related to primitive antiarchs that are morphologically close to species reported from the Late Silurian and Early Devonian in China (Janvier and Tong-Dzuy, 1988). The overlying Middle Devonian Van Huong For- mation of the section shows comparable fau- nal elements and exhibits similar fluviodeltaic facies settings comparable to Givetian to Late Königshof P., et al./Vietnam Journal of Earth Sciences 39 (2017) 320 Devonian sediments along the southeastern coast of China (Long et al., 1990; Lee, 1991; Jones et al., 1997). 6. Conclusions Detrital zircons from two Devonian siliciclastic rocks, the Van Canh and the Van Huong Formations from the Do Son Peninsu- lar (NE Vietnam) were analyzed for U, Th, and Pb isotopes by LA-SF ICP-MS tech- niques. The youngest zircon of each formation exhibits maximum ages of sedimentation at 407.1±9.5 Ma (Van Canh Formation) and 406.3±4.0 Ma (Van Huong Formation) which confirms published biostratigraphic age data. The zircon cluster of both samples from the east Red River Basin as well as palaeontologi- cal affinities to South China, confirms recon- structions for NE Vietnam close to the west- ern Himalayas suggested by earlier studies. Acknowledgements The paper is a contribution to IGCP 596- Climate Change and Biodiversity Patterns in the Mid-Paleozoic (Early Devonian to Late Carboniferous). Funding by the first-author (P.K.) is acknowledged by the Deutsche For- schungsgemeinschaft (DFG Project KO- 1622/15-1). We thank both anonymous re- viewers for their constructive comments which helped to improve the manuscript. We also thank Prof. Sarah K. Carmichael (Appa- lachian State University, Boone, USA) for checking the English of the final version. 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