GEOCHEMISTRY OF TRIASSIC DEPOSITS IN EASTERN LINQING DEPRESSION AND ITS TECTONIC SIGNIFICANCE
-
摘要:
碎屑沉积岩的物质组成对其形成的构造背景具有重要的指示作用。通过对临清坳陷东部三叠系碎屑沉积岩样品地球化学主量和微量元素分析表明:三叠系岩石样品主要为成熟度较低的杂砂岩和长石砂岩;碎屑沉积岩的母岩总体上与大陆地壳组成基本一致,原岩以沉积岩和花岗岩为主;临清坳陷东部中生代早—中三叠世处于靠近大陆岛弧的活动大陆边缘构造环境,其动力学机制与早期秦岭洋壳向华北板块俯冲、晚期扬子板块和华北板块碰撞作用有关。研究结果为确定三叠纪时期华北东部南侧的构造环境提供了地球化学方面的证据。
Abstract:The mineral composition of clastic sedimentary rocks is an important indicator to tectonic setting of the sediments. In this paper, we analyzed the major and trace elements of the Triassic clastic deposits sampled from the Eastern Linqing Depression. Results show that, the Triassic samples are mainly greywacke and arkose with low maturity. The parent rock of the clastic sedimentary rock is consistent with continental crust in general which mainly are sedimentary rocks and granite, and the Eastern Linqing Depression was a tectonic environment of active continental margin close to the continental island arc in Early-Middle Triassic Epoch. The dynamic mechanism can be connected to the subduction of the Qinling ocean crust beneath the North China plate in early stage and the collision between the Yangtze plate and North China plate later on. This study provides the geochemical evidence for determining the tectonic environment of the south side to the eastern North China in Triassic period.
-
Key words:
- Triassic /
- geochemistry /
- tectonic setting /
- Eastern Linqing Depression
-
-
图 7 临清坳陷东部三叠纪碎屑沉积岩构造环境图解(据文献[2])
Figure 7.
表 1 临清坳陷东部三叠系碎屑沉积岩的主量(%)、微量(10-6)元素含量
Table 1. Content of major and trace elements in Triassic clastic sedimentary rocks
样品 LQ-1 LQ-2 LQ-3 LQ-4 SiO2 62.57 68.86 73.46 58.47 TiO2 0.67 0.48 0.33 0.56 Al2O3 14.32 12.61 9.5 12.93 TFe2O3 5.85 4.41 1.43 4.68 MnO 0.06 0.04 0.04 0.12 MgO 3.7 1.99 0.72 2.44 CaO 2.23 1.98 4.81 7.65 Na2O 2.01 2.54 2.41 2.57 K2O 3.63 3.11 2.27 2.68 P2O5 0.18 0.066 0.1 0.097 LOI 4.66 3.8 4.84 7.58 总计 99.88 99.89 99.91 99.78 Sc 13.6 10.8 6.6 11.5 Cr 56.2 43.2 33.2 48.5 Co 12.7 6.27 2.73 8.5 Ni 26.6 14.3 8.63 16 Zn 68 40.7 22.6 54.4 Rb 140 112 66 93.7 Sr 425 678 428 558 Cs 6.91 5.26 2.01 4.39 Ba 632 1747 974 1750 La 42.9 32.6 24.2 41.2 Ce 83.7 64.7 45.8 67.2 Pr 9.92 7.5 5.47 8.45 Nd 36.8 26 19.8 29.9 Sm 6.73 4.52 3.7 5.3 Eu 1.47 1.06 0.924 1.16 Gd 5.57 3.53 2.92 4.42 Tb 0.924 0.615 0.484 0.755 Dy 4.76 3.17 2.63 3.89 Ho 0.91 0.584 0.527 0.783 Er 2.5 1.72 1.49 2.23 Tm 0.441 0.3 0.254 0.424 Yb 2.48 1.72 1.5 2.63 Lu 0.43 0.291 0.257 0.451 Zr 157 136 101 154 Hf 4.47 3.52 2.72 3.89 Ta 1.06 0.705 0.621 0.851 Th 11.7 9.5 6.31 10.9 U 1.99 2.05 2.03 2.15 ∑REE 199.54 148.31 109.96 168.79 (La/Yb)N 11.69 12.81 10.90 10.59 (La/Sm)N 4.01 4.54 4.12 4.89 (Gd/Yb)N 1.82 1.66 1.58 1.36 δEu 0.73 0.81 0.86 0.73 -
[1] 姚纪明, 于炳松, 陈建强, 等.中扬子北缘上侏罗统-白垩系沉积岩地球化学特征与构造背景分析[J].地球化学, 2009, 38(3):231-241. doi: 10.3321/j.issn:0379-1726.2009.03.002
[2] Roser B P, Korsch R J. Determination of tectonic setting of sandstone-mudstone suites using SiO2 content and K2O/Na2O ratios[J]. Journal of Geology, 1986, 94(5): 635-650. doi: 10.1086/629071
[3] Taylor S R, McLennan S M. The Continental Crust: Its Composition and Evolution[M]. Oxford: Blackwell, 1985: 1-312.
[4] Bhatia M R, Crook K A W. Trace element characteristics of graywackes and tectonic setting discrimination of sedimentary basins[J].Contributions to Mineralogy and Petrology, 1986, 92(2): 181-193. doi: 10.1007/BF00375292
[5] Odigi M I, Amajor L C. Ceochemical characterization of Cretaceous sandstones from the Southern Benue Trough, Nigeria[J]. Chinese Journal of Geochemistry 2009, 28(1):44-54. doi: 10.1007/s11631-008-0384-8
[6] 屈李华, 刘喜方, 李金锁, 等.北羌塘三叠系康鲁组沉积岩地球化学特征及其物源区和构造背景分析[J].现代地质, 2015, 29(4):789-803. doi: 10.3969/j.issn.1000-8527.2015.04.008
[7] 刘本立.地球化学基础[M].北京:北京大学出版社, 1994:186-187.
[8] 王明健, 张训华, 何登发, 等.临清坳陷东部断裂系统与上古生界煤成气成藏[J].中国矿业大学学报, 2013, 42(3):394-404. http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=zgkydxxb201303011
[9] 王明健, 张训华, 何登发, 等.临清坳陷东部早—中侏罗世地层剥蚀量恢复与原型盆地[J].特种油气藏, 2012, 19(6):17-21. doi: 10.3969/j.issn.1006-6535.2012.06.004
[10] Condie K C. Chemical composition and evolution of the upper continental crust: contrasting results from surface samples and shales[J].Chemical Geology, 1993, 104(1-4):1-37. doi: 10.1016/0009-2541(93)90140-E
[11] Bhatia M R. Plate tectonics and geochemical composition of sandstones[J]. Journal of Geology, 1983, 91(6): 611-627. doi: 10.2307/30064711
[12] 吴智平, 侯旭波, 李伟.华北东部地区中生代盆地格局及演化过程探讨[J].大地构造与成矿学, 2007, 31(4):385-399. doi: 10.3969/j.issn.1001-1552.2007.04.001
-