Geochemical Characteristics and Tectonic Significance of the Granotoids in the Western Section of the Mid-Qilian
Hou Rongna1, Wang Shuhua1, Zhang Xiang2, Hou Kexuan1, Zhang Cheng3, Wang Jinrong1
1.Key Laboratory of Mineral Resources in Western China (Gansu Province), School of Earth Sciences, Lanzhou University, Lanzhou 730000, China
2. Geological Survey of Gansu Province, Lanzhou 730000, China
3. Second Institute of Geological and Mineral Exploration of Gansu Provincial Bureau of Geology and Mineral Resources, Lanzhou 730000, China
Abstract
Granotoids, mainly gabbro, diorite and granite, are greatly rich in the northern and southern parts of Shibandun area, western section of the Mid-Qilian. LA-ICP-MS zircon and U-Pb dating methods indicate that the age of the rock from the northern belt were(469.3±2.8)Ma,(461.2±3.3)Ma and (470.0±2.5) Ma, respectively. The SiO2 content of the northern rock mass ranges from 53.2% to 66.1% with high content of the Al, Ti, Mg, Fe, Ca, K, Na in the rock mass and A/CNK<1.1. The rock analysis shows enrichment of large ion lithophile elements (LILE) ( e.g., Rb, K) and Pb, and depletion of high field strength elements (HFSE) ( e.g., Nb, Ta, Ce, Sr, Hf and Ti). The results also indicate LREE enriched pattern with high ∑REE abundance, flat HREE and moderate negative Eu anomaly ( δEu=0.6). Tectonic discrimination diagrams showed that the samples are located in the arc environment. The age of the rock from the southern belt are respectively (470.9±2.8) Ma and (472.3±4.2) Ma based on LA-ICP-MS zircon U-Pb dating methods. The southern rock mass contains high amount of the Al, Mg, Fe, Ca and is rich in Na and poor in K (A/CNK<1.1). Rock analysis results show the enrichment of large ion lithophile elements (LILE) ( e.g., Rb, K and Sr) and depletion of high field strength elements (HFSE) ( e.g., Nb, Ta, Ti and P), and also indicate a LREE enriched pattern with rather low ∑REE, depleted HREE and obvious differentiation in Eu, which is from slight negative to positive anomaly ( δEu=0.74~1.18). Our study shows that the northern belt was formed by partial melting of mantle wedge in an island-arc environment, while the southern belt is adakites generated by partial melting of Adakites, and is also the product from the magmatic process by the North Qilian southward subduction. The western part of the Mid-Qilian is an island arc hyperplasia complex created on a remained microcontinental in early Paleozoic.
Keyword:
The western section of the Mid-Qilian; Island arc; Adakites; Early Paleozoic.
表2 中祁连西段花岗岩类的地球化学成分(主量元素:质量百分含量, %, 微量与稀土元素:× 10-6)Table.2 The geochemical composition of the western section of the Central Qilian granitoid rock(Major element: weight, %; Trace and REE element:× 10-6)
样号
YQ-6
YQ-9
YQ-10
YQ-11
YQ-26
YQ-27
元素
闪长岩
辉长岩
正长花岗岩
花岗闪长岩
花岗闪长岩
花岗岩
SiO2
53.2
51.56
61.67
66.11
67.13
70.73
Al2O3
16.97
17.4
16.97
15.58
16.42
15.86
TiO2
2
1.98
0.92
0.8
0.45
0.31
TFe2O3
11.58
12.09
6.32
5.14
3.39
2.31
MnO
0.19
0.21
0.09
0.08
0.06
0.04
MgO
3.32
3.16
1.36
1.09
2.34
1.17
Ca0
6.01
6.35
4.08
2.91
4.61
2.97
Na2O
4.31
4.22
4.26
3.91
4.01
4.67
K2O
1.83
1.99
4.02
4.1
1.53
1.85
P2O5
0.61
1.04
0.3
0.29
0.06
0.08
Mg#
36.21
34.1
29.83
29.69
57.77
50.11
Li
12.2
15.96
34.24
30.5
35.16
25.46
Sc
24.14
26.2
11.87
9.59
9.38
4.55
Ti
12125.8
14806
5504.08
5414
2834.8
1910.57
V
192.9
135.58
95.01
59.68
90.26
56.19
Cr
22.22
55.34
5.71
5.22
21.58
8.38
Co
23.12
25.72
10.01
8.57
11.89
5.56
Ni
15.55
36.98
6.04
7.39
14.51
5.63
Cu
34.68
42.78
23.55
18.52
20.28
1.57
Zn
119.26
136.86
77.71
66.96
36.48
41.72
Ga
27.26
29.94
22.65
21.16
16.57
16.61
Rb
71.24
86.76
174.1
175.24
57.24
61.1
Sr
272.2
311
175.44
173.24
399.6
386.57
Zr
332.4
499.14
444.9
328.14
54.46
106.04
Nb
21.44
29.61
16.44
20.02
4.56
7.08
Cs
2.38
1.84
6.89
6.22
3.28
2.77
Ba
490.8
625.4
738.19
641
453
418.88
Hf
8.28
9.42
11.82
7.1
1.33
2.61
Ta
1.04
1.8
0.99
1.63
0.36
0.49
Pb
8.41
6.52
17.19
16.32
11.66
14.58
Th
3.84
1.76
13.7
11.74
5.85
6.99
U
0.89
0.98
1.99
1.76
1.14
1.39
La
32.12
33.34
38.41
31.9
8
22.02
Ce
73.86
84.54
77.94
64.7
15.64
37.63
Pr
10.2
11.34
9.62
7.6
1.99
3.89
Nd
42.82
51.18
36.57
30.14
7.72
12.37
Sm
10.29
12.59
7.95
6.54
2.13
1.88
Eu
2.76
3.3
1.65
1.34
0.53
0.64
Gd
11.27
13.6
8.12
6.63
2.25
1.47
Tb
1.76
2.14
1.24
1.04
0.35
0.18
Dy
11.03
13.24
7.78
6.39
2.11
0.96
Ho
2.21
2.67
1.54
1.3
0.39
0.17
Er
6.37
7.57
4.48
3.76
1.1
0.5
Tm
0.98
1.05
0.69
0.54
0.16
0.07
Yb
5.99
6.72
4.31
3.54
1
0.46
Lu
0.89
0.99
0.64
0.53
0.14
0.07
Y
74.36
66.16
53.38
32.5
13.75
6.3
∑ REE
286.9
310.43
254.34
198.43
57.24
88.62
LREE
172.05
196.28
172.14
142.22
36
78.44
HREE
114.85
114.15
82.2
56.2
21.24
10.18
δ Eu
0.78
0.77
0.63
0.62
0.74
1.18
δ Ce
1
1.07
0.99
1.02
0.96
1
La/Sm
3.12
2.65
4.83
4.88
3.76
11.74
Sm/Nd
0.24
0.25
0.22
0.22
0.28
0.15
(La/Yb)N
3.85
3.56
6.39
6.47
5.76
34.19
注:分析测试由西北大学大陆动力学国家重点实验室完成。Mg# = 100Mg/(TFe+Mg)
表2 中祁连西段花岗岩类的地球化学成分(主量元素:质量百分含量, %, 微量与稀土元素:× 10-6)Table.2 The geochemical composition of the western section of the Central Qilian granitoid rock(Major element: weight, %; Trace and REE element:× 10-6)
图7 石板墩地区花岗岩类微量元素蛛网图及稀土元素配分图[73]Fig.7. Primary mantle-normalized trace element spider diagram and chondrite-normalized REE patterns for acgranitoid rock[73]
WangQuan, LiuXueya. Paleo-oceanic crust of the Chilienshan religion, western China and its tectonic significance[J]. , 1976, 1: 42-55. [王荃, 刘雪亚. 我国西部祁连山区的古海洋地壳及其大地构造意义[J]. , 1976, 1: 42-55. ][本文引用:2]
[2]
XiaoXuchang, ChenGuoming, ZhuZhizhi. A preliminary study on the tectonics of ancient ophiolites in the Qilian Mountain, northwest of China[J]. , 1978, 52: 287-295. [肖序常, 陈国铭, 朱志直. 祁连山古蛇绿岩带的地质构造意义[J]. , 1978, 52: 287-295. ][本文引用:1]
ZhaoShenggui. The Characteristics of Qilian Orogenic belt and its tectonic evolution[J]. , 1996, 5(1): 16-29. [赵生贵. 祁连造山带特征及其构造演化[J]. , 1996, 5(1): 16-29. ][本文引用:1]
[5]
Feng YM, He SP. Orogenic process of the Qilian Mountains[J]. , 1996, 76(2): 1-5. [本文引用:1]
[6]
WanYusheng, XuZhiqin, YangJingsui, et al. The Precambrian high-grade basement of the Qilian terrane and neighboring areas: Its ages and compositions[J]. , 2003, 24(4): 319-324. [万渝生, 许志琴, 杨经绥, 等. 祁连造山带及邻区前寒武纪深变质基底的时代和组成[J]. , 2003, 24(4): 319-324. ][本文引用:1]
[7]
LuSongnian, LiHuaikun, WangHuichu, et al. Detrital zircon population of Proterozoic metasedimantary strata in the Qinling-Qilian-Kunlun Orogen[J]. Acta Petrologica Sinica, 2009, 25(9): 2 195-2 208. [陆松年, 李怀坤, 王惠初, 等. 秦·祁·昆造山带元古宙副变质岩层碎屑错石年龄谱研究[J]. 岩石学报, 2009, 25(9): 2 195-2 208. ][本文引用:1]
[8]
XuZhiqin, YangJingsui, LiHaibing, et al. The early Palaeozoic terrene framework and the formation of the Hhigh-Pressure(HP) and Ultra-High Pressure(UHP) metamorphic belts at the Central Orogenic Belt (COB)[J]. Acta Geologica Sinica, 2006, 80(12): 1 793-1 806. [许志琴, 杨经绥, 李海兵, 等. 中央造山带早古生代地体构架与高压/超高压变质带的形成[J]. 地质学报, 2006, 80(12): 1 793-1 806. ][本文引用:1]
[9]
YangJingsui, XuZhiqin, MaChangqian, et al. Compound orogeny and scientific problems concerning the Central Orogenic Belt of China[J]. , 2010, 37(1): 1-11. [杨经绥, 许志琴, 马昌前, 等. 复合造山作用和中国中央造山带的科学问题[J]. , 2010, 37(1): 1-11. ][本文引用:1]
[10]
WangJinrong, WuChunjun, CaiZhenghong, et al. Early Paleozoic high-Mg adakite from Yindongliang in the eastern section of the North Qilian: Implications for geodynamics and Cu-Au mineralization[J]. Acta Petrologica Sinica, 2006, 22(11): 2 655-2 664. [王金荣, 吴春俊, 蔡郑红, 等. 北祁连山东段银铜粱早古生代高镁埃达克岩: 地球动力学及成矿意义[J]. 岩石学报, 2006, 22(11): 2 655-2 664. ][本文引用:1]
[11]
SongShuguang, NiuYaoling, SuLi, et al. Tectonics of the North Qilian orogen[J]. Gondwana Research, 2013, 23(4): 1 378-1 401. [本文引用:1]
[12]
XuZhiqing, XuHuifen, ZhangJianxin, et al. The Zoulangshan Caledonian subductive complex in the Northern Qilian Mountains and its dynamics[J]. , 1994, 68(1): 1-15. [许志琴, 徐惠芬, 张建新, 等. 北祁连走廊南山加里东俯冲杂岩增生地体及其动力学[J]. , 1994, 68(1): 1-15. ][本文引用:2]
[13]
ZhangQi, SunXiaomeng, ZhouDejin, et al. The characteristics of North Qilian opliiolites environment of fomation and their tectonic significance[J]. Advances in Earth Science, 1997, 12(4): 366-393. [张旗, 孙晓猛, 周德进, 等. 北祁连蛇绿岩的特征, 形成环境及其构造意义[J]. 地球科学进展, 1997, 12(4): 366-393. ][本文引用:1]
[14]
SongShuguang. Tectonic evolution of subductive complex belts in the North Qilian Mountains[J]. Advances in Earth Science, 1997, 12(4): 351-365. [宋述光. 北祁连山俯冲杂岩带的构造演化[J]. 地球科学进展, 1997, 12(4): 351-365. ][本文引用:1]
[15]
SongShuguang, ZhangLifei, NiuY, et al. Zircon U-Pb SHRIMP ages of eclogites from the North Qilian Mountains in NW China and their tectonic implication[J]. , 2004, 49(6): 592-595. [宋述光, 张立飞, NiuY, 等. 北祁连山榴辉岩SHRIMP定年及其构造意义[J]. , 2004, 49(6): 592-595. ][本文引用:1]
[16]
SongShuguang. High-pressure metamorphic rocks in the North Qilian oceanic subduction zone, China: A review[J]. , 2009, 28(12): 1 769-1 778. [宋述光. 北祁连山古大洋俯冲带高压变质岩研究评述[J]. , 2009, 28(12): 1 769-1 778. ][本文引用:1]
[17]
XiaXiaohong, SongShuguang. Forming age and tectono-petrogenises of the Jiugequan ophiolite in the North Qilian Mountain, NW China[J]. , 2010, 15(15): 1 465-1 473. [夏小洪, 宋述光. 北祁连山肃南九个泉蛇绿岩形成年龄和构造环境[J]. , 2010, 15(15): 1 465-1 473. ][本文引用:1]
[18]
WuCailai, XuXueyi, GaoQianming, et al. Early Palaezoic granitoid magmatism and tectonic in North Qilian, NW China[J]. Acta Petrologica Sinica, 2010, 26(4): 1 027-1 044. [吴才来, 徐学义, 高前明, 等. 北祁连早古生代花岗质岩浆作用及构造演化[J]. 岩石学报, 2010, 26(4): 1 027-1 044. ][本文引用:1]
[19]
WuCailai, YangJingsui, YangHongyi, et al. Dating of two types of granite from north Qilian, China[J]. Acta Petrologica Sinica, 2004, 20(3): 425-432. [吴才来, 杨经绥, 杨宏仪, 等. 北祁连东部两类I型花岗岩定年及其地质意义[J]. 岩石学报, 2004, 20(3): 425-432. ][本文引用:1]
[20]
ZhangQi, ChenYu, ZhouDejin, et al. Geochemical characteristics and genesis of Dachadaban ophiolite in North Qilian area[J]. Science in China (Series D), 1998, 41(3): 277-281. [本文引用:1]
TsengChien-Yuan, YangHuai-Jen, YangHoung-Yi, et al. Continuity of the North Qilian and North Qinling orogenic belts, Central Orogenic System of China: Evidence from newly discovered Paleozoic adakitic rocks[J]. Gondwana Research, 2009, 16(2): 285-293. [本文引用:1]
[23]
WuCailai, GaoYuanhong, Ronald FrostB, et al. An early Palaeozoic double-subduction model for the North Qilian oceanic plate: Evidence from zircon SHRIMP dating of granites[J]. International Geology Review, 2011, 53(2): 157-181. [本文引用:2]
[24]
HouQingye, ZhaoZhidan, ZhangHongfei, et al. Indian Ocean-MORB-type isotopic signature of Yushigou ophiolite in North Qilian Mountains and its implications[J]. Science in China (Series D), 2006, 49(6): 561-572. [本文引用:1]
[25]
Smith AD, Yang HY. The neodymium isotopic and geochemical composition of serpentinites from ophiolitic assemblages in the Qilian fold belt, northwest China[J]. Journal of Asian Earth Sciences, 2006, 28(2): 119-132. [本文引用:1]
[26]
QiuJiaxiang, ZengGuangce, ZhuYunhai. Characteristics and latitudinal comparative research on the early palaeozoic volcanic rocks of riftedorogenic belt and small ocean basinophiolite suit from northern Qinling Mountains and southern Qilian Mountains[J]. , 1998, 4(4): 393-405. [邱家骧, 曾广策, 朱云海, 等. 北秦岭—南祁连早古生代裂谷造山带火山岩与小洋盆蛇绿岩套特征及纬向对比[J]. , 1998, 4(4): 393-405. ][本文引用:1]
[27]
ZhangWangsheng, FengGuangsheng, GaoShan, et al. Metamorphic core complex structure and uplifting mechanism in Lajishan-Hualong area[J]. , 2003, 28(4): 407-413. [张旺生, 冯光胜, 高山, 等. 拉脊山—化隆变质核杂岩构造及其隆升机制探讨[J]. , 2003, 28(4): 407-413. ][本文引用:1]
[28]
ZhangZhaowei, LiWenyuan, GaoYongbao, et al. ID-TIMS zircon U-Pb age of Yulonggou intrusive rocks in Southern Qilian Mountains and its geological significance[J]. , 2012, 31(2/3): 455-462. [张照伟, 李文渊, 高永宝, 等. 南祁连裕龙沟岩体ID-TIMS锆石U-Pb年龄及其地质意义[J]. , 2012, 31(2/3): 455-462. ][本文引用:1]
[29]
LiuZhiwu, WangChongli, ShiXiaohu. Granitoids characteristics and tectonic setting of Danghenanshan area in South Qilian Mountains[J]. , 2006, 20(4): 545-554. [刘志武, 王崇礼, 石小虎. 南祁连党河南山花岗岩类特征及其构造环境[J]. , 2006, 20(4): 545-554. ][本文引用:1]
[30]
LiuZhiwu, WangChongli. Granitoid geochemistry and gold-copper mineralization in the Danghenanshan area, Southern Qilian Mountains[J]. , 2007, 43(1): 64-73. [刘志武, 王崇礼. 南祁连党河南山花岗岩类地球化学及其金铜矿化[J]. , 2007, 43(1): 64-73. ][本文引用:2]
[31]
YongYong, XiaoWenjiao, YuanChao, et al. Geochronology and geochemistry of Paleozoic granitic plutons from the eastern Central Qilian and their tectonic implications[J]. , 2008, 24(4): 855-866. [雍拥, 肖文交, 袁超, 等. 中祁连东段古生代花岗岩的年代学、地球化学特征及其大地构造意义[J]. , 2008, 24(4): 855-866. ][本文引用:1]
[32]
ChenJunlu, XuXueyi, ZengZuoxun, et al. Geochemical characters and LA-ICPMS zircon U-Pb dating constraints on the petrogenesis and tectonic setting of the Shichuan intrusion, east segment of the Central Qilian, NW China[J]. , 2008, 24(4): 841-854. [陈隽璐, 徐学义, 曾佐勋, 等. 中祁连东段什川杂岩基的岩石化学特征及年代学研究[J]. , 2008, 24(4): 841-854. [本文引用:1]
[33]
GuoJinjing, ZhaoFengqing, LiHuaikun. Jinningian Col lisional Granite Belt in the Eastern Sector of the Central Qilian massif and its implication[J]. , 1999, 20(1): 10-15. [郭进京, 赵凤青, 李怀坤. 中祁连东段晋宁期碰撞型花岗岩及其地质意义[J]. , 1999, 20(1): 10-15. ][本文引用:1]
[34]
GuoJinjing, ZhaoFengqing, LiHuaikun, et al. New chronological evidence of the age of Huangyuan Group in the eastern segment of Mid-Qilian massif and its geological significance[J]. , 2000, 19(1): 26-31. [郭进京, 赵凤青, 李怀坤, 等. 中祁连东段湟源群的年代学新证据及其地质意义[J]. , 2000, 19(1): 26-31. ][本文引用:1]
[35]
HeShiping, WangHonglung, ChenJuanlu, et al. LA-ICP-MS U-Pb zircon geochronology of basic dikes within Maxianshan Rock Group in the Central Qilian Mountains and its tectonic implications[J]. , 2008, 33(1): 35-45. [何世平, 王洪亮, 陈隽璐, 等. 中祁连马衔山岩群内基性岩墙群锆石LA-ICP-MS U-Pb年代学及其构造意义[J]. , 2008, 33(1): 35-45. ][本文引用:1]
[36]
YanHaiqing, QianZhuangzhi, LiuJiqing, et al. New evidences of Micropaleoplants for the time of the Gaolan rock Group in the eastern section of the central Qilian Mountains[J]. Geological Review, 2005, 51(2): 113-119. [闫海卿, 钱壮志, 刘继庆, 等. 中祁连山东段皋兰岩群地质时代的微古植物新证据[J]. 地质论评, 2005, 51(2): 113-119. ][本文引用:1]
[37]
WangErqi, ZhangQi, Burchfiel CB. The Lajishan Fault Belt in Qinghai Province: A multi-staged uplifting structural window[J]. , 2000, 35(4): 493-500. [王二七, 张旗, Burchfiel CB. 青海拉鸡山: 一个多阶段抬升的构造窗[J]. , 2000, 35(4): 493-500. ][本文引用:2]
[38]
SuJianping, HuNenggao, FuGuomin. High-pressure metamorphism of granet-bearing amohibolite in the Gongchakou region, Western Qilian Mountains and its geological implication[J]. , 2004, 24(4): 391-397. [苏建平, 胡能高, 付国民. 祁连西段龚岔口地区榴闪岩的高压变质作用及其地质意义[J]. , 2004, 24(4): 391-397. ][本文引用:2]
[39]
SuJianping, HuNenggao, ZhangHaifeng, et al. U-Pb Zircon dating and genesis of the Heigouliangzi granitic intrusion in the western segment of the Middle Qilian Mountains[J]. , 2004, 18(1): 70-74. [苏建平, 胡能高, 张海峰, 等. 中祁连西段黑沟梁子花岗岩的锆石U-Pb同位素年龄及成因[J]. , 2004, 18(1): 70-74. ][本文引用:1]
[40]
SuJianping, ZhangXinhu, HuNenggao, et al. Geochemical characteristics and genesis of adakite-like granites at Yema Nanshan in the western segment of the Central Qilian Mountains[J]. , 2004, 31(4): 365-371. [苏建平, 张新虎, 胡能高, 等. 中祁连西段野马南山埃达克质花岗岩的地球化学特征及成因[J]. , 2004, 31(4): 365-371. ][本文引用:1]
[41]
LiJianFeng, ZhangZhicheng, HanBaofu. Geochronology and geochemistry of Early Paleozoic granitic plutons from Subei and Shibaocheng areas, the western segment of Central Qilian and their geological implications[J]. Acta Petrologica Sinica, 2010, 26(8): 2 431-2 444. [李建锋, 张志诚, 韩宝福. 中祁连西段肃北、石包城地区早古生代花岗岩年代学、地球化学特征及其地质意义[J]. 岩石学报, 2010, 26(8): 2 431-2 444. ][本文引用:1]
[42]
WangJinrong, ZhangXinhu, ZhangXiang, et al. Tectonics, Rock Combination and petrogenesis of Yema-Nanshan from the western segment of the Central Qilian[C]∥, 2012: 466-468. [王金荣, 张新虎, 张翔, 等. 中祁连西段野马南山构造岩石组合、成因及其构造意义[C]∥, 2012: 466-468. ][本文引用:2]
[43]
DongGuoan, YangHuairen, YangHongyi, et al. SHRIMP U-Pb Zircon geochronology of Precambrian basement from the Qilian massif and their tectonic implications[J]. Chinese Science Bulletin, 2007, 52(13): 1 572-1 585. [董国安, 杨怀仁, 杨宏仪, 等. 祁连地块前寒武基底锆石SHRIMP U-Pb年代学及其地质意义[J]. 科学通报, 2007, 52(13): 1 572-1 585. ][本文引用:1]
[44]
ZuoGuochao, LiuJichen. The evolution of Tectonic of Early Paleozoic in North Qilian Range , China[J]. Chinese Journal of Geology, 1987, (1): 14-24. [左国朝, 刘寄陈. 北祁连早古生代大地构造演化[J]. 地质科学, 1987, (1): 14-24. ][本文引用:2]
[45]
XiaLinqi, XiaZuchun, RenYouxiang, et al. [M]. Wuhan: China University of Geosciences Press, 1991. [夏林圻, 夏祖春, 任有祥, 等. [M]. 武汉: 中国地质大学出版社, 1991. ][本文引用:1]
[46]
FengYimin, HeShiping. Ophiolite and orogeny: Annalysis for the northe Qilian orogenie belt as an exemple[M]∥ZhangQi, ed. . Beijing: Geological Publish House, 1996: 135-138. [冯益民, 何世平. 蛇绿岩与造山作用——北祁连造山带例析[M]//张旗编. . 北京: 地质出版社, 1996: 135-138. ][本文引用:1]
[47]
XuWangchun, ZhangHongfei, LiuXiaoming. U-Pb zircon dating constraints on formation time of Qilian high-grade metamorphic rock and its tectonic implications[J]. , 2007, 52(4): 531-538. [徐旺春, 张宏飞, 刘小明. 锆石U-Pb定年限制祁连山高级变质岩系的形成时代及其构造意义[J]. , 2007, 52(4): 531-538. ][本文引用:1]
[48]
WanYusheng, XuZhiqin, YangJingsui, et al. Ages and compositions of the precambrian high-grade basement of the Qilian Terrane and its adjacent areas[J]. , 2001, 75(4): 375-384. [本文引用:1]
[49]
WanYusheng, ZhangJianxin, YangJingsui, et al. Geochemistry of high-grade metamorphic rocks of the North Qaidam mountains and their geological significance[J]. Journal of Asian Earth Sciences, 2006, 28: 174-184. [本文引用:1]
[50]
LuoMingfei. Research on Early Palaeozoic Tectonic Characters of DHNS, GS[D]. , 2010. [罗明非. 甘肃党河南山早古生代大地构造性质研究[D]. , 2010. ][本文引用:1]
[51]
Lu SN, Yang CL, Li HK, et al. A group of rifting events in the terminal Paleoproterozoic in the North China Craton[J]. Gondwana Research, 2002, 5: 123-131. [本文引用:1]
[52]
WuHuaichun, ZhangShihong, LiZhengxiang, et al. New paleomagnetic results from the Yangzhuang Formation of the Jixian System, North China, and tectonic implications[J]. Chinese Science Bulletin, 2005, 50(14): 1 483-1 489. [本文引用:1]
XiaLinqi, XiaZuchun, XuXueyi. Early Palaeozoic Mid-ocean Ridge-ocean Island and Back-arc basin volcanism in the north Qilian Mountains[J]. , 1998, 72(4): 301-312. [夏林圻, 夏祖春, 徐学义. 北祁连山早古生代洋脊—洋岛和弧后盆地火山作用[J]. , 1998, 72(4): 301-312. ][本文引用:1]
[55]
ZhangJianxin, XuZhiqin, ChenWen, et al. A Tentative discussion on the ages of the subduction-accretionary complex/ volcanic arcs in the middle sector of North Qilian Mountain[J]. , 1997, 16: 112-119. [张建新, 许志琴, 陈文, 等. 北祁连中段俯冲—增生杂岩/火山弧的时代探讨[J]. , 1997, 16: 112-119. ][本文引用:1]
[56]
ZhangJianxin, XuZhiqin, XuHuifen, et al. Framework of north Qilian Caledonian subduction-accretionary wedge and its deformation dynamics[J]. , 1998, 33: 290-299. [张建新, 许志琴, 徐惠芬, 等. 北祁连加里东期俯冲—增生楔结构及动力学[J]. , 1998, 33: 290-299. ][本文引用:1]
LiuChuanzhou, XiaoWenjiao, YuanChao, et al. The petrological and geochemical characteristics of the Zhamashi complex, Qilian Mountain and their tectonic implications[J]. Acta Petrologica Sinica, 2005, 21(1): 57-64. [刘传周, 肖文交, 袁超, 等. 祁连山扎麻什基性杂岩体岩石地球化学特征及其大地构造意义[J]. 岩石学报, 2005, 21(1): 57-64. ][本文引用:1]
[59]
ZuoGuochao, WuHanquan. A bisubduction-collision orogenic model of early-paleozoic in the middle part of North Qilian area[J]. Advances in Earth Science, 1997, 12(4): 315-312. [左国朝, 吴汉泉. 北祁连中段早古生代双向俯冲—碰撞造山模式剖析[J]. 地球科学进展, 1997, 12(4): 315-312. ][本文引用:3]
[60]
WuCailai, YaoShangzhi, YangJingsui, et al. Double subduction of the Early Paleozoic North Qilian oceanic plate: Evidence from granites in the central segment of North Qilian, NW China[J]. , 2006, 33(6): 1 198-1 208. [吴才来, 姚尚志, 杨经绥, 等. 北祁连洋早古生代双向俯冲的花岗岩证据[J]. , 2006, 33(6): 1 198-1 208. ][本文引用:1]
[61]
WangYonghe, JiaoYangquan, LiJianxing, et al. Ordovician magmatic arc stratum of the Middle Qilian Block[J]. , 2008, 22(5): 724-732. [王永和, 焦养泉, 李建星, 等. 中祁连北缘奥陶纪岩浆弧地层[J]. , 2008, 22(5): 724-732. ][本文引用:2]
[62]
QiRuirong. LA-ICP-MS Zircon U-Pb ages and geological implications for the Bagadeerji Granitic plutons in the central Qilian Mountains, Gansu[J]. , 2012, 32(4): 86-93. [齐瑞荣. 中祁连西段巴嘎德尔基岩体 LA-ICP-MS锆石U-Pb年龄及地质意义[J]. , 2012, 32(4): 86-93. ][本文引用:1]
[63]
WangHonghao, LiJianghai, YangJingyi, et al. Paleo-plate Reconstruction and Drift Path of Tarim Block from Neoproterozic to Early Palaeozoic[J]. Advances in Earth Science, 2013, 28(6): 637-647. [王洪浩, 李江海, 杨静懿, 等. 塔里木陆块新元古代—早古生代古板块再造及漂移轨迹[J]. 地球科学进展, 2013, 28(6): 637-647. ][本文引用:1]
[64]
CompstonW, Williams IS, Kirschvink JL, et al. Zircon U-Pb ages for the Early Cambrian time-scale[J]. Journal of Geological Society of London, 1992, 149: 171-184. [本文引用:1]
[65]
SongBiao, ZhangYumei, WanYusheng, et al. Mount making and procedure of the SHRIMP dating[J]. , 2002, 48(Suppl. ): 26-30. [宋彪, 张玉梅, 万渝生, 等. 锆石SHRIMP样品靶制作、年龄测定及有关现象讨论[J]. , 2002, 48(增刊): 26-30. ][本文引用:1]
[66]
GovindarajuG. Compilation of working values and sample description for 383 geostand ards[J]. Geostand ards Newsletter, 1994, 18: 1-158. [本文引用:1]
[67]
Li XH. Geochemistry of the Longsheng ophiolite from the southern margin of Yangtze craton, SE China[J]. Geochemical Journal, 1997, 31: 323-327. [本文引用:1]
[68]
LiuYe, LiuXiaoming, HuZhaochu, et al. Evaluation of accuracy and long-term stability of determination of 37 trace elements in geological samples by ICP-MS[J]. Acta Petrologica Sinica, 2007, 23(5): 1 203-1 210. [刘晔, 柳小明, 胡兆初, 等. ICP-MS测定地质样品中37个元素的准确度和长期稳定性分析[J]. 岩石学报, 2007, 23(5): 1 203-1 210. ][本文引用:1]
[69]
Pidgeon RT, Nemchin AA, Hitchen GJ. Internal strctures of zircons from Archaean granites from the Darling Range batholith: Implications for zircon stability and the interpretation of zircon U-Pb ages[J]. Contribution to Mineralogy Petrology, 1998, 132: 288-299. [本文引用:1]
[70]
Le Maitre RW, StreckeisenA, ZanettinB, et al. A Classification of Igneous Rock Sand Glossary of Terms[M]. , 1989. [本文引用:1]
[71]
Rickwood PC. Boundary lines within petrologic diagrams which use oxides of major and minor elements[J]. Lithos, 1989, 22(4): 247-263. [本文引用:1]
Sun SS, McDonoughW F. Chemical and isotopic systematics of oceanic basalts: Implications for mantle composition and processes[J]. Geological Society, London, Special Publications, 1989, 42(1): 313-345. [本文引用:1]
Castillo PaternoR. An overview of adakite petrogenesis[J]. Chinese Science Bulletin, 2006, 51(3): 257-268. [本文引用:1]
[76]
Rapp RP, ShimuzuN. Arc-magmatism in hot subduction zones: Interactions between slab-derived melts and the mantle wedge and the petrogenesis of adakites and high magnesium and esites (HMA)[C]∥, 1996, 1: 497. [本文引用:1]
[77]
Defant MJ, Drummond MS. Derivation of some modern arc magmas by melting of Young subducted lithosphere[J]. Nature, 1990, 347: 662-665. [本文引用:2]
[78]
Defant MJ, Drummond M S. Mount St. Heles: Potential example of the partial melting of the subducted Lithosphere in a volcanic arc[J]. Geology, 1993, 21: 547-550. [本文引用:1]
[79]
Kay SM, Romas VA, MarquezM. Evidence in Cerro pampa volcanic rocks for slab-melting prior to ridge-trench collision in southern South America[J]. The Journal of Geology, 1993, 101: 703-714. [本文引用:1]
[80]
MartinH. Adakitic magmas: Modern analogues of Archaean granitoids[J]. Lithos, 1999, 46: 411-429. [本文引用:1]
[81]
Drummond MS, Defant MJ. A model for Trondhjemite-Tonalite-Dacite Genesis and Crustal Growth Via Slab Melting: Archean to Modern Comparisons[J]. Journal of Geophysical Research: Solid Earth, 1990, 95(B13): 21 503-21 521. [本文引用:1]
[82]
PeccerilloA, Taylor SR. Geochemistry of eocene Calc-Alkaline volcanic rocks from the Kastamonu area, Northern Turkey[J]. Contributions to Mineralogy and Petrology, 1976, 58(1): 63-81. [本文引用:1]
[83]
ZhangQi, WangYan, QianQing, et al. The characteristics and tectonic-metallogenic significances of the adakites in Yanshan period from eastern China[J]. Acta Petrologica Sinica, 2001, 17(2): 236-244. [张旗, 王焰, 钱青, 等. 中国东部燕山期埃达克岩特征及其构造—成矿意义[J]. 岩石学报, 2001, 17(2): 236-244. ][本文引用:1]
[84]
ZhangQi, QianQing, WangErqi, et al. An east China plateau in mid-late Yanshanian period: Implication fromadakites[J]. , 2001, 36(2): 248-255. [张旗, 钱青, 王二七, 等. 燕山中晚期的中国东部高原: 埃达克岩的启示[J]. , 2001, 36(2): 248-255. ][本文引用:1]
[85]
ZhangQi, WangYan, WangYuanlong. Preliminary study on the components of the lower crust in east China Plateau during Yanshanian period: Constraints on Sr and Nd isotopic composltions of adakite-like rocks[J]. Acta Petrologica Sinica, 2001, 17(4): 505-513. [张旗, 王焰, 王元龙. 燕山期中国东部高原下地壳组成初探: 埃达克质岩Sr、Nd同位素制约[J]. 岩石学报, 2001, 17(4): 505-513. ][本文引用:1]
[86]
XiaLinqi, XiaZuchun, XuXueyi. Dynamics of Tectono-volcano-magmatic evolution from North Qilian Mountains, China[J]. , 1995, (1): 1-28. [夏林圻, 夏祖春, 徐学义. 北祁连山构造—火山岩浆演化动力学[J]. , 1995, (1): 1-28. ][本文引用:1]
[87]
HouQingye, ZhaoZhidan, ZhangHongfei, et al. Indian Ocean-MORB-type isotopic signature of Yushigou ophiolite in North Qilian Mountains and its implications[J]. , 2005, 35(8): 710-719. [侯青叶, 赵志丹, 张宏飞, 等. 北祁连玉石沟蛇绿岩印度洋MORB型同位素组成特征及其地质意义[J]. , 2005, 35(8): 710-719. ][本文引用:1]
[88]
SongShuguang, ZhangGuibin, ZhangCong, et al. Dynamic process of oceanic subduction and continental collision: Petrological constraints of HP-UHP belts in Qilian-Qaidam, the northern Tibetan Plateau[J]. Chinese Science Bulletin, 2013, 58: 2 240-2 245. [宋述光, 张贵宾, 张聪, 等. 大洋俯冲和大陆碰撞的动力学过程: 北祁连—柴北缘高压—超高压变质带的岩石学制约[J]. 科学通报, 2013, 58: 2 240-2 245. ][本文引用:1]
According to the data of detrital zircon population the Beidahe,Hualong,Huangyuan,Jinshuikou,Douling and Qinling complex-groups, which are thought to be Palaeoproterozoic in age before, at least part of the strata including all selected samples should belong to the Late Mesoproterozoic or Early Neoproterozoic. The data also illustrate that the eroded area of the strata are characterized by developed Early Mesoproterozoic materials, but only less Palaeoproterozoic ones. So all involved samples show a similar feature of the detrital zircon population.
①Institute of Geology, Chinese Academy of Sciences, Beijing 100029;②Engineering and Technology College, Science and Techn
The North Qilian ophiolites, with the characteristics mainly of MORB and boninite, were mostly formed at back arc and island arc environment and emplaced over island arc accretion wedge and active continental margin. So, It is possible that the North Qilian ophiolites similar to that of Cordilleran type by geochemical and emplaced characteristics. In North Qilian ophiolite belt, a volcanic sedimentary sequence lies conformably on the top of the ophiolite section, as in the Laohushan and Jiugequan area. The pillow lava at the top of the ophiolite is originated from the magma chamber beneath the spreading ridge, while the pillow lava in the overlying rock sequence is formed from partial melting of the depleted asthenospheric mantle off ridge, so they have different tectonic significance respectively. In the paper, the framework of plate tectonic of early Paleozoic North Qilian, and the periods and scale of North Qilian ocean basin were disccused. It can also be inferred that the North Qilian oceanic basin was a part of the Paleo Asian oceanic, and the scale of the North Qilian ocean basin was probably very large, and similar to that of today’s Pacific ocean.
Xi'an Institute of Geology and Mineral Resources,CAGS,Xi'an 710054
The North Qilian Mountains are located between the Middle Qilian Qaidam Massif and the Alaskan Massif which is the west part of Sin korea Craton. It is one of the most typical continent orogenic belt in China. In this orogenic belt, there are rift volcanic rocks from Sinian to Middle Cambrain, ophiolites from late Cambrain to Ordovician, island arc volcanic rocks from middle to late Ordovician, extensional basin volcanic sedimentary rocks of late Ordovician, residual sea basin flysh of Silurian and Devonian molasse. The ophiolites, which mainly distribute in three belts, show similar geochemical characteristics( except for Dachadaban ophiolite), with the tendency of becoming younger from south to north. In Sunan Qilian region, the middle part of the North Qilian Mountains, two different Caledonian subductive complex belts, namely, the southern deep level subductive complex belt and the northern shallow level subductive complex belt, occur parallelly. The southern belt consists of trench olistostrome and graywacke, ophiolitic blocks,and rift volcanic rocks, etc., with some been transformed into eclogites and high grade blueschists by high pressure metamorphism and distributing as three tectonic slices in the deep level subductive complex belt. Deformation and metamorphic analysis suggest not only a clockwise, retrogressive P T t D path, but also a kinetic variation of plate movements from subduction to strike slip shear to upthrusting. The northern shallow level subductive complex belt consists of graywacke, ophiolite and low grade blueschists, mixed with some island arc volcanic rocks. The P T condition of low grade blueschists is 150~250℃, 0.4~0.7GPa, reflecting high pressure metamorphism at shallow level or anchi surface. The two complex belts were probably formed at different depth of the same subduction zone, and the characteristics of petrology, metamorphism and deformation reveal a tectonic evolution history of transition from rift to oceanization to subduction to arc continent collision to orogenesis.
Zircon SHRIMP dating of granitoids from the middle segment of North Qilian showed that they are 512 Ma and 501 Ma for plagiogranite and quartz diorite from Kokoli, 508Ma for Yemazhui granite, and 424Ma for Jinfusi granite, respectively. Based on petrogeochemistry of granites and occurrence in tectonics, combined with the dating of other granites and regional geological data, we think that North Qilian oceanic plate was subducted southward under the Middle Qilian terrane, which caused two episodes of magmatism, one was forming Kokoli plagiogranite (512Ma), Yemazui granite (508Ma) and Kokoli quartz diorite (501Ma), another forming Niuxinshan granite (477Ma). Lately, subduction polarity for the North Qilian basin changed from southward to northward because it was blocked by the deep subduction of Qaidam continental plate northward on the south of Qilian, which formed Minleyaogou granite (463Ma). After about 440 Ma, the Qilian Ocean was closed because of collision between Qaidam and Alax terrane, forming the North Qilian orogen. The post-collision granites such as Jinfusi granite (424Ma) and Niuxinshan quartz diorite (435Ma), and so on, were formed in the North Qilian Orogen where different blocks stretched and collapsed because of lithosphere delamination below the orogen.
Dating the Gaolan Group in the Central Qilian fold basement is important for reconstructing the evolution of the Qilian Orogenic Belt. As a result of the lack of fossil and that isotopic age determination is disordered by magmatism, the geological age of the Gaolan Group has not been determined for a long time. We found a lot of micropaleoplants of the Jixian period in the area. At the same time, a Sm-Nd isochron age of 1180 Ma is obtained. According to the regional stratigraphic correlation, isotopic age and micropaleoplants, we put the Gaolan Group in the Mesoproterozoic.
Precise SHRIMP zircon U-Pb dating and geochemical composition analysis have been applied to Early Paleozoic granitic plutons from Subei and Shibaocheng areas. SHRIMP zircon U-Pb ages of the granitic plutons from Subei and Shibaocheng areas emplaced during Early Paleozoic are 415±3Ma and 435±4Ma, respectively. The concentrations of TiO 2 , Al 2 O 3 , MgO, CaO, Fe 2 O 3 and Mg # decrease with increasing SiO 2 contents, implying magmatic differentiation model controlled by hornblende and plagioclase fractionation. Subei pluton is higher in ∑REE content, ranging from 118.7×10 -6 ~202.2×10 -6 , with strong fractionation of LREE/HREE, (La /Yb) N =11.1~16.5, and has slightly δ Eu anomaly. Shibaocheng pluton is lower in ∑REE, ranging from 19.7×10 -6 ~59.0×10 -6 , also with strong fractionation of LREE/HREE, (La /Yb) N =6.68~44.8, but with δ Eu positive anomaly and inverse V shape. On chondrite-normalized REE fractional, the sub-parallel pattern indicates a co-genetic relation for all the samples. The concentrations of large ion lithophile elements (LILE), such as Rb, K, Sr are enriched, whereas the high field strength elements(HFSE)(e.g. Nb and Ta)as well as P and Ti contents are depleted. On the Rb-Y+Nb diagrams, all plots from Subei pluton set in the area to island arc type, whereas Shibaocheng pluton in the area of island arc type. Combined with the geological setting, Subei pluton is the result of post-collision during Late Caledonian and Shibaocheng pluton formed in island arc tectonic environment.
对中祁连西段肃北、石包城地区花岗岩进行了精确的SHRIMP 锆石U-Pb 定年和地球化学成分分析。SHRIMP 锆石U-Pb定年表明,肃北岩体和石包城岩体侵位年龄均属早古生代,分别为415±3Ma和435±4Ma。地球化学分析表明,随着SiO 2 含量的增加,TiO 2 、Al 2 O 3 、MgO、CaO、Fe 2 O 3 、Mg # 等的含量相应下降,这表明该套岩石是角闪石和斜长石的分离作用控制下岩浆分异的产物。肃北岩体稀土元素总量较高,∑REE介于118.7×10 -6 ~202.2×10 -6 之间,轻稀土相对富集,(La/Yb) N =11.1~16.5,具微弱 δ Eu异常。石包城岩体稀土元素总量较低,∑REE介于19.7×10 -6 ~59.0×10 -6 之间,轻稀土相对富集,(La/Yb) N =6.68~44.8, δ Eu正异常而呈倒“V”型。岩石富集大离子亲石元素Rb、K、Sr等,亏损Nb和Ta等高场强元素以及P和Ti。在微量元素判别图解上,肃北岩体所有岩石投影点落后碰撞区域,石包城岩体的岩石投影点落在岛弧区。结合区域地质背景,石包城岩体可能产出于洋壳俯冲的岛弧环境,而肃北岩体是加里东造山作用晚期陆陆碰撞后的产物。
1. Institute of Geology, Geological Bureau of Gansu, Lanzhou; 2. Geological Team No. 2, Geological Bureau of Qinghai
North Qilian range was a intercontinental micro-oceanic basin of Early Paleozoic.Using the field data and chemical composition data, it is possible to reconstruct plate-tectonic histories tracing back to Early Paleozoic.During Sinian, the North Qilian Range began to be separated from North China plate, whereas the major rifting occurred during Middle Cambrian, it was dominantly convergent of geosyncline of North Qilian during Late Ordovician and Early-Middle Silurian. Late Silurian and Early Devonian are characterized by the development of complex subduction systems.The tectonic elements of Early Paleozoic of North Qilian can be divided into:1. South slope eugeoclin: 1)The north slope of Zoulangnanshan rift valley zone(Z); 2)The north slope of Tuolashan rift valley zone(t-O 1 ); 3)Yingjushan-Qingclaban rift valley zone(t 2 -O 1 ); 4)Tuolaishan-Dabanshan-Jiaolongzhang rift valley zone(O 1-3 ); 5)Julidaban-Jingyanling-Baiyinchang volcanic arc(t z -3); 6)Yingou-Mayaxueshan-Baiyinchang volcanic arc(O 1-2 ): 7)Yushugoushan-Lenglongling-Laohushan volcanic arc(O 1-3 ); 8)Chaidanuoshan-Chilien-Heicigou island arc(S 1-z ).2. North slope miogeocline: 1)Zhangye-Wuwei continental slope(t 1 -S 2 ); 2)Jingtai-Zhougwei Shelf(t 2 -S 3 ).3. Sunan-Lenglongling-Jingtai intermountane trough zone(D).
The Zhamashi mafic complex in Qilian County, Qinghai province, intruded into Cambrian-Ordovician strata, is mainly composed of gabbro with ultramafic rock, pyroxenite, hornblendite and diorite. Petrological and geochemical studies suggest that the complex is derived from a calc-alkalic magma by crystallization with different degree. The rocks are enriched in LILE and depeleted in HFSE, with clearly Nb and Ta negative anomalies. Combined with the spatial relationship between the complex and the northerly Qingshuigou-Baijinshi subduction complex, we conclude that the Zhamashi complex formed in an island arc setting, and may be as product of southward subduction of North Qilian ocean crust to the north.
Institute of Geoscience,Gansu Bureau of Geologyand Mineral Resources,Lanzhou 730000;Xi'an Institute of Geology and Mineral Resources,Xi'an 710054
A tectonic evolution model of Early Paleozoic in the middle part of North Qilian Area is put forward based on the field investigation of more than ten years, and a series of comprehensive researches, including volcanic sedimentary association, the characteristics of the complex in high pressure metamorphism zone, subduction complex rock zone, granitic magmatism and isotopic age, etc. In Sinian, paleocontinental crust broke up, and micro ocean basin was formed with remnant fragmants of continental crust. In Cambrian Ordovician, asymmetric bisubduction took place southward and northward respectively with Heihe Babaohe Zone being a spreading ridge. During the northward subduction, progressive back arc extension gave rise to a new ocean crust. This type of events took place northward repeatedly, and their correspondant products, subduction complexes, were elevated back to the surface and transformed into convergent transitional crusts. During the southward subduction, the earlier extentional transition crusts were transformed to Alaska type active continental margins which subducted southward, and subsequently arc back extensional basin was formed . In Silurian, with subduction ended and the oceanic basin disappearing, a tectonic framework with the coexistence of island chains and turbidity trough was formed. In Devonian, an orogenic belt with new continental crust was formed as the result of the convergence and collision between the Alaskan massif and the Middle Qilian massif.
1.Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, Peking University, Beijing 100871,China; 2.School of Earth and Space Sciences, Peking University, Beijing 100871,China
The Neoproterozoic strata which mainly distributes in the periphery of the Tarim Block records lots of Tectonothermal events related to the assembly and breakup of the Rodinia Supercontinent, yet the positon of the Tarim Block in Rodinia and how the Tarim Blcok moved after the breakup of Rodinia remains controversial. Based on the collection and selection of the published paleomagnetic data and the paleomagnetism method, we obtain the paleolatitude and drift path from Neoproterozoic to early Paleozoic of the Tarim Block.Moreover, combined with our field work and the isotope chronology data of representative rocks such as A type granite, mafic dyke swarms, continental flood basalt and bimodal volcanic rocks in the Tarim’s periphery, we conclude that there was a strongly rifting event surrounding the Tarim Block during 830~700 Ma BP,which caused the Tarim Block breaking off the Rodinia Supercontinent. However, the separation was not complete, and the Tarim block joined the Gandwana Supercontinent along with Australia.Through comparing the variation of the paleolatitude of the Tarim Block and the Australia Plate, we conclude that their separation time was about 450 Ma BP. Then, the Tarim Block drifted towards north, and joined the Laurentia Supercontinent in late Paleozoic. During the Neoproterozoic to early Paleozoic, the Tarim block, on the whole, presented a drift parh from high north latitude to south latitude, and had a rapid return process to north latitude in the Ordovician.
塔里木陆块周缘的新元古界地层记录了涉及Rodinia聚合和裂解的构造热事件,但塔里木在Rodinia超大陆中的位置以及在Rodinia裂解后如何运动尚无定论。采用收集的古地磁数据,并结合塔里木西北缘阿克苏地区的野外工作以及塔里木周缘代表性岩石如A型花岗岩、基性岩墙群、大陆溢流玄武岩和双峰式火山岩等的同位素年代学数据,将塔里木陆块从Rodinia超大陆中裂解的时间限制在830~700 Ma BP。之后,塔里木陆块随澳洲板块一起加入冈瓦纳大陆。约在450 Ma BP,塔里木陆块和澳洲板块发生分离,并快速北漂,最终在晚古生代加入劳亚大陆。新元古代—早古生代,塔里木陆块整体上从北半球较高纬度向南半球漂移,并在奥陶纪向北半球快速回返。
Adakite is a suite of intermediate acid igneous rocks characterized by HREE depletion and no obvious negative Eu anomaly, indicating the derivation from very deep source with garnet in the residue. A lot of Yanshanian intermediate acid magmatic rocks in eastern China have similar geochemical characteristics to the adakite, their formation environment however is unrelated to subduction process. In this paper, adakite is divided into two types: one is O type adakite, which is characterized by Na enrichment and is related to subduction process; another is C type adakite, which is enriched in K (most of them are still enriched in Na, a few K enriched), is probably a product of partial melting of the lower crust granulite in the thickened crust (>50km) resulted from underplating of basaltic magma. The occurrence of C type adakites in eastern China is indicative to the explanation of the geological phenomenon of Yanshanian magmatism. Because C type adakite can preserve some imprints of the lower crust, it in turn can trace the composition of the lower crust and discuss metallogenesis related to the lower crust and crust mantle process.