31 3 2011 9 Sedimentary Geology and Tethyan Geology Vol. 31 No. 3 Setp. 2011 1009-3850 2011 03-0088-07 430205 - - - Rb K Ba Th Sr Nb Ta Ti P P588. 1 A 1990 1 20 1 25 40 ~ 50 2 5cm 15 30cm 10 ~ 20mm 100 ~ 200m 1 - - NW-SE 3 2 5 ~ 3 8cm 1 0. 5% ~ 1% 132Ma U-Pb 4 1 2011-03-28 2011-06-30 1964-1212010782005
2011 2 89 Table 1 1 U-Pb U-Pb isotopic determinations of zircon in quartz diorite from the Jiarongjiandegongka intrusive rocks 1 Qh al pal - Qp 3 - TB b 3 - TB 3 a - T 3 K - K 1 γδ J - K 1 δi J - K 1 δο J - YZS - BNS - - XJS - - KQS - - Fig. 1 Simplified geological map of the Jiarongjiandegongka region Qh al pal = Quaternary alluvial deposits Qp 3 = Quaternary pluvial and alluvial deposits TB c 3 = upper member of the Banyan Formation of the Bayan Har Group TB b 3 = middle member of the Banyan Formation of the Bayan Har Group TB a 3 = lower member of the Banyan Formation of the Bayan Har Group T 3 K = Kenan Group K 1 γδ J = Jiarongjiandegongka granodiorite. K 1 δi J = Jiarongjiandegongka tonalite K 1 δo J = Jiarongjiandegongka quartz diorite YZS = Yarlung Zangbo suture zone BNS = Bangong Lake-Nujiang suture zone XJS = Xijir Ulan-Jinshajiang suture zone KQS = Kunlun-Qinling suture zone 1. 1 NW-SE 2 SiO 2 59. 26% ~ 68. 19% 0. 9km 2 0. 4km 2 SiO 2 59. 26% ~ 61. 58% / 60. 30% ALK = 3. 96% ~ 4. 29% 4. 12% An = 32 65% ~ 69% 5% ~ 10% 5% 34. 5km 2 36. 5km 2 18. 5km 2 35. 5km 2 An = 28 ~ 33 60% ~ 63% 15% ~ 18% 0% ~ 1% 8% ~ 10% 5% ~ 8% / / 1. 3 TB c 3-3 4. 5km 2 1. 0km 2 NW-SE 3. 4km 2 An = 29 ~ 30 55% ~ 59% 7% ~ 9% 20% ~ 23% 5% ~ 7% 3% ~ 4% 2 Na 2 O > K 2 O σ = 0. 86 ~ 1. 01 A /CNK = 0. 84 ~ 0. 98 SiO 2 ~ 12% 8% ~ 10% 56. 20% ~ 65. 92% 62. 62% ALK = 3. 97 ~ 5. 49% 4. 79% Na 2 O > K 2 O σ = 0. 87 ~ 1. 45 A /CNK = 0. 86 ~ 1. 02 1. 2 - SiO 2 64. 12% ~ 68. 19% 65. 51% ALK NW - SE = 4. 56%
90 2 Table 2 2 /% Chemical compositions % of the Jiarongjiandegongka intrusive rocks ~ 5. 49% 5. 22% Na 2 O > K 2 O σ = 0. 82 ~ 1. 40 A /CNK = 0. 93 ~ 0. 99 SiO 2 SiO 2 - Na 2 O + K 2 O SiO 2 - K 2 O 2 2 SiO 2 -K 2 O 3 3. 1 Fig.2 SiO 2 -K 2 O diagram for the Jiarongjiandegongka intrusive rocks = granodiorite = tonalite = quartz diorite
2011 2 91 = 0. 64 ~ 0. 86 Eu - 3 La /Yb n = 4. 99 ~ La /Yb n = 7. 50 6. 18δEu = 0. 81 ~ 0. 92 Eu 5. 47 ~ 7. 33 6. 44 δeu = 0. 73 ~ 1. 03 0. 84 Eu - La /Yb n = 4. 90 ~ 10. 05 6. 93 δeu 1. 16 δeu Table 3 3 3 / 10-6 REE contents 10-6 in the Jiarongjiandegongka intrusive rocks 4 MORB 3 Leedy MORB Beviens et al. 1984 Fig. 3 Chondrite-normalized REE distribution patterns for the Fig. 4 MORB-normalized trace element spidergrams for the Jiarongjiandegongka intrusive rocks chondrite values from Jiarongjiandegongka intrusive rocks MORB values from Beviens Leedy et al. 1984 3. 2 0. 60 0. 48 Rb / Sr > 0. 5 Nb /Ta = 6. 04 ~ 25. 05 13. 56 4 MORB 4 4 17. 5 11 4 Rb Green 1995 1 La /Nb = 1. 39 ~ 7. 01 K Ba Th Sr Nb Ta 7. 01 16 2. 31 Ti P 0. 94 2. 2 P Ti Rb /Sr = 0. 29 ~
92 2 Table 4 4 / 10-6 Trace element contents 10-6 in the Jiarongjiandegongka intrusive rocks 4 Sr Nd Pb Sr Nd 5 εsr t 110 εnd t -8. 4 ~ -9. 2 εsr t 100. 5 ~ 122. 7 εnd t -εsr t 5 Ⅳ Table 5 5 Nd Sr Nd and Sr isotopic compositions in the Jiarongjiandegongka intrusive rocks 6 Pb β- γ 6 3a 5 5 εnd t -εsr t Fig. 5 εnd t vs. εsr t diagram for the Jiarongjiandegongka intrusive rocks - - - SiO 2 59. 26% ~ 68. 19% A / CNK = 0. 85 ~ 1. 02 - ALK = 3. 90 ~ 5. 49% Na 2 O > K 2 O Rb K Ba Th Nb /Ta = 6. 04 ~ 25. 05 13. 56 17. 5 11 Green 1995 1
2011 2 93 Table 6 6 Pb Pb isotopic compositions in the Jiarongjiandegongka intrusive rocks 6 Pb β - γ 1. 2. 3. 3a ORG 3b 4. 5. 6. Fig. 7 Rb vs. Y + Nb discriminant diagram after Pearce et 7. 8. 9. 10. Fig. 6 β vs. γ diagram for Pb isotopes 1 = mantle-derived lead 2 = upper crust-derived lead 3 = mixed upper crust- and mantle-derived lead 3a = magmatism 3b = sedimentation 4 = chemical-sedimentary lead 5 = submarine hydrothermal lead 6 = mesometamorphic to hypometamorphic lead 7 = hypometamorphic lower crust-derived lead 8 = orogenic lead 9 = upper crust-derived lead from old shale 10 = retrograde metamorphic lead La /Nb = 1. 39 ~ 7. 01 2. 31 0. 94 2. 2 εnd t -8. 4 ~ -9. 2 87Sr /86Sr i 0. 71170 ~ 0. 71299 Pb β - γ 6 8 Rb - Yb + Ta VAG WPG 3a ORG Rb-Y + Nb Rb-Yb + Ta Fig. 8 Rb vs. Yb + Ta discriminant diagram 7 8 VAG = volcanic arc granites WPG = within plate granites S- COLG = syn-collision granites ORG = ocean ridge granites 7 Rb - Y + Nb VAG WPG S - COLG al. 1984 VAG = volcanic arc granites WPG = within plate granites S-COLG = syn-collision granites ORG = ocean ridge granites S - COLG
94 2 - - - - - Rb K Ba Th Sr Nb Ta Ti P 2-4 εnd t -8. 4 ~ -9. 2 87Sr /86Sr i - 0. 71170 ~ 0. 71299 P - T 2 Bird 1978 5 2002 6 1 GREEN T H. Significance of Nb /Ta as an indicator of geochemical processes in the crust-mantle system J. Chem. 4 Geol. 1995 120 3-4 347-359. A 2. M. 1993. 3. M. 1993 15-150. 4. M. 1997 41-75. 6 1-5 BIRD P. Initiation of intracontinental subduction in the Himalaya J. J. Geophys. Res. 1987 83 4975-4978. 6. J. 2001 75 4 484-497. Geochemistry and tectonic setting of the Jiarongjiandegongka intrusive rocks in Qumarleb Qinghai BAI Yun-shan NIU Zhi-jun DUAN Qi-fa TANG Chao-yang LI Li PANG Ying-chun Wuhan Center China Geological Survey Wuhan 430205 Hubei China Abstract The intrusive sequences in Jiarongjiandegongka Qinghai consist of quartz diorite tonalite granodiorite and syenogranite. The lithochemical compositions display the evolution from intermediate basic to acidic rocks and the magmas are rich in silica and alkali. The geochemical signatures are characterized by the enrichment of LREE enrichment of large ion lithophile elements such as Rb K Ba and Th slight depletion of Sr Nb and Ta and strongly depletion of Ti and P. The tectonic setting of the Jiarongjiandegongka intrusive rocks are assigned to syn-collision granites and may be traced back to the Early Cretaceous. Key words Jiarongjiandegongka intrusive sequence tectonic setting intrusive rock southern Qinghai