Silurian-Devonian Intrusive Rocks and Tectonic Environment in Copulae of Kunlun-Qinling Mountains
-
摘要: 通过详细的地质填图和年代学研究,确定昆秦接合部存在志留-泥盆纪岩浆活动,采用单颗粒锆石U-Pb定年方法测定侵入岩的形成时代为382~423Ma,即志留-泥盆纪.岩体以小岩株、岩脉及构造岩片产出,普遍受后期构造作用,多数以构造片岩卷入海西期苦海-赛什塘构造混杂岩带内.岩性有石英闪长岩、英云闪长岩、花岗闪长岩及二长花岗岩4种,属于典型的钙碱性系列.常量和微量元素特征及构造环境判别显示,其形成于岛弧或陆缘弧及同碰撞构造环境,反映了原特提斯洋壳俯冲消减及随后的陆壳碰撞过程.该阶段侵入岩在侵入时代和形成的构造环境上,与东昆仑早古生代岩浆活动一致,因此,昆秦接合部发育的志留-泥盆纪岩浆弧向西可与东昆仑早古生代岩浆岩带相接.志留-泥盆纪侵入岩产出的地质特征及其形成的构造环境进一步说明,昆秦接合部地区古特提斯多岛小洋盒形成于弧后扩张作用,与原特提斯洋的关闭紧密相关.Abstract: Silurian-Devonian magmatic activity was discovered in the copulae of the Kunlun-Qinling mountains by detailed mapping and chronology analysis. Single grain zircon U-Pb dating yielded formation dates of 382-423 Ma in the intrusive rocks, which is Silurian-Devonian. The intrusive bodies are output in stocks, dikes and tectonic slices, which were suffered from later tectonism and evolved in the Kuhai-Saishitang Hercynian mélange belt as tectonic slices. The rock types are quartz-diorite, tonalite, granodiorite and monzonite granite, belonging to typical calc-alkali rocks. The characteristics of trace elements, main elements and tectonic environment discrimination reveal that the rocks were formed in an island arc tectonic environment or a continental margin arc tectonic environment. Some were also formed in a syncollisional tectonic environment, which reflects the stages of the prototethys ocean subduction and later continental crust collision. In that period intrusive rocks are in accordance with the East Kunlun Early Paleozoic magmatic activity zone, so it is suggested that a Silurian-Devonian magmatic arc developed in the copulae between the Kunlun-Qinling mountains, which joins the East Kunlun Early Paleozoic magmatic rock zone to the west. The geological characteristics and tectonic environment of the Silurian-Devonian intrusive rock in the copulae between Kunlun-Qinling Mountains indicated that the Paleotethys archipelagic ocean was formed in back-arc expandation, which was closely related to the close of the prototethys ocean.
-
图 1 昆秦接合部构造单元及志留-泥盆纪侵入岩分布
1.裂解基底岩片; 2.蛇绿岩; 3.第四系; 4.滑脱带构造单元边界; 5.走滑断层; 6.逆冲带构造单元边界; 7.逆冲断层; 8.采样位置及同位素年龄; 9.岩体位置; Pt1b.白沙河岩组; TL.隆务河群; TH.洪水川群; γδT3.晚三叠世花岗闪长岩; 构造岩片: Sch.龙通片岩(Pt1b); lgn.沙乃亥片麻岩(Pt1); Yβ.雅日玄武岩(P); Psmo.塞日科龙洼蛇绿混杂岩(P); Pms.雪穷糜棱片岩(P); Pmav.曲龙中酸性火山岩(P); Ptu.双龙浊积岩(P); 志留-泥盆纪花岗岩: δoS3.喔尔日石英闪长岩; oγS3.曲龙英云闪长岩; δoD1.乎若合石英闪长岩; γδD1.唉呀日山花岗闪长岩; ηγD1.扎那合惹二长花岗岩
Fig. 1. Tectonic unit and S-D intrusive rock distribution in copulae of Kunlun-Qinling mountain
图 3 稀土配分曲线和微量元素蛛网图(球粒陨石标准化值据Taylor and Mclennan, 1985;洋脊花岗岩值据Pearce et al., 1984)
Fig. 3. REE distribution patterns and spider diagram of trace elements
图 5 花岗岩R1-R2图解(Batchelor and Bowden, 1985)
1.地幔分异花岗岩; 2.碰撞前花岗岩; 3.碰撞后隆起花岗岩; 4.造山晚期—晚造山期花岗岩; 5.非造山区花岗岩; 6.同碰撞花岗岩; 7.造山后花岗岩
Fig. 5. R1-R2 diagram for granites
图 6 花岗岩w (Nb)-w (Y)、w (Rb)-w (Y+Nb) 判别图(Pearce et al., 1984)
Fig. 6. w (Nb)-w (Y) and w (Rb)-w (Y+Nb) discrimination diagram for granites
表 1 志留-泥盆纪侵入岩常量元素(10-2)、稀土元素及微量元素分析(10-6) 结果
Table 1. Analyses results of major, trace and rare earth elements from S-D intrusive rocks
表 2 侵入岩单颗粒锆石铀-铅年龄测定结果
Table 2. Single grain Zircon U-Pb dating results of intrusive rocks
-
[1] Batchelor, R.A., Bowden, P., 1985. Petrogenetic interpretation of granitoid rock series using multi-cationic parameters. Chem. Geol. , 48(1): 43-55. [2] Chen, N.S., Sun, M., Zhang, K.X., et al., 2001. 40Ar-39Ar and U-Pb ages of metadiorite from the eastern Kunlun orogenic belt: Evidence for early-Paleozoic magmatic zone and excess argon in amphibole minerals. Chinese Science Bulletin, 46(4): 330-333. doi: 10.1007/BF03187197 [3] Pan, Y.S., Kong, X.R., 1998. Lithosphere structure, evolution and dynamics of Qinghai-Xizang(Tibetan) plateau. Guangdong Science & Technology Press, Guangzhou(in Chinese). [4] Pearce, J.A., Harris, N.B.W., Tindle, A.G., 1984. Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. F. Petrol. , 25: 956-983. [5] Taylor, S. R., McLennan, S. M., 1985. The continental crust: Its composition and evolution. Blackwell, Oxford. [6] Wang, B.Z., Zhang, Z.Y., Zhang, S.Q., et al., 2000. Geological features of Lower Paleozoic Ophiolith in KuhaiSaishitang region, eastern section of Eastern Kunlun. Earth Science—Journal of China University of Geosciences, 25(6): 592-598(in Chinese with English abstract). [7] Yin, H.F., Zhang, K.X., 1998. Evolution and characterstics of central orogenic belt. Earth Science—Journal of China University of Geosciences, 23(5): 437-441(in Chinese with English abstract). [8] Yin, H.F., Zhang, K.X., Feng, Q.L., 2004. The archipelagic ocean system of eastern Eurasian Tethys. Acta Geologica Sinica, 78(1): 230-236. [9] Zhang, K.X., Lin, Q.X., Zhu, Y.H., et al., 2004. New paleotological evidence on time determination of the east part of the eastern Kunlun mélange and its tectonic significance. Science in China(Series D), 47(10): 865 873. [10] Zhang, K.X., Huang, J.C., Yin, H.F., et al., 2000. Application of radiolarians and other fossils in non-Smith strata: Exemplified by the Animaqing mélange belt in eastern Kunlun Mountains. Science in China(Series D), 43(4): 364-374. doi: 10.1007/BF02959447 [11] Zhang, K.X., Yin, H.F., Zhu, Y.H., et al., 2001. Theory, method and practice to geological mapping in mélange district of orogenic belts. China University of Geosciences Press, Wuhan(in Chinese). [12] Zhang, K.X., Zhu, Y.H., Yin, H.F., et al., 2004. Application of tectonic facies in geological mapping in East Kunlun orogenic belt. Earth Science—Journalo fChina University of Geosciences, 29(6): 661-666(in Chinese with English abstract). [13] Zhang, Z.Y., Yin, H.F., Wang, B.Z., et al., 2004. Presence and evidence of Kuhai-Saishitang branching ocean in copulae between Kunlun-Qinling Mountains. Earth Science—Journal of China University of Geosciences, 29 (6): 691-696(in Chinese with English abstract). [14] Zhu, Y.H., Wang, G.C., Jia, C.X., et al., 2003. Early Paleozoic volcanism in Nuomuhongguole area, East Kunlun orogenic belt. Earth Science—Journal of China University of Geosciences, 28(6): 606-614(in Chinese with English abstract). [15] Zhu, Y.H., Zhang, K.X., Pan, Y., et al., 1999. Determination of different ophiolitic belts in eastern Kunlun orogenic zone and their tectonic significance. Earth Science—Journal of China University of Geosciences, 24 (2): 134-138(in Chinese with English abstract). [16] 潘裕生, 孔祥儒, 1998. 青藏高原岩石圈结构演化和动力学. 广州: 广东科技出版社. [17] 王秉璋, 张智勇, 张森琦, 等, 2000. 东昆仑东端苦海-赛什塘地区晚古生代蛇绿岩的地质特征. 地球科学———中国地质大学学报, 25(6): 592-598. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX200006009.htm [18] 殷鸿福, 张克信, 1998. 中央造山带的演化及其特点. 地球科学———中国地质大学学报, 23(5): 437-441. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX805.000.htm [19] 张克信, 殷鸿福, 朱云海, 等, 2001. 造山带混杂岩区地质填图理论、方法与实践. 武汉: 中国地质大学出版社. [20] 张克信, 朱云海, 殷鸿福, 等, 2004. 大地构造相在东昆仑造山带地质填图中的应用. 地球科学———中国地质大学学报, 29(6): 661-666. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX200406003.htm [21] 张智勇, 殷鸿福, 王秉璋, 等, 2004. 昆秦接合部海西期苦海-赛什塘分支洋的存在及其证据. 地球科学———中国地质大学学报, 29(6): 691-696. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX200406007.htm [22] 朱云海, 王国灿, 贾春兴, 等, 2003. 东昆仑造山带诺木洪郭勒早古生代火山活动. 地球科学———中国地质大学学报, 28(6): 606-614. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX200306004.htm [23] 朱云海, 张克信, Pan Yuanming, 等, 1999. 东昆仑造山带不同蛇绿岩带的厘定及其构造意义. 地球科学———中国地质大学学报, 24(2): 134-138. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX902.005.htm -
下载:
点击查看大图
计量
- 文章访问数: 3507
- HTML全文浏览量: 103
- PDF下载量: 3
- 被引次数: 0
