青藏高原东南部贡嘎山海螺沟冰川冰下沉积物形成与变形

doi:10.7522/j.issn.1000-0240.2013.0129

摘要/Abstract

摘要： 冰岩界面的冰川动力学是冰川系统的重要组成部分, 海螺沟冰川地处温暖湿润的海洋环境, 冰川运动速度较快, 冰川底部接近压融点, 是研究冰下过程的较理想地点. 在海螺沟冰川大型磨光面上浅显侵蚀坑内发现了碎屑物质. 对碎屑物质理化特征研究表明: 粒度特征、地球化学与石英砂SEM 分析表明沉积在冰岩界面上的物质来自于冰川底部的底碛层, 而不是冰上环境的产物. 偏光显微镜下观察到的冰下沉积物呈现出一系列塑性变形(微旋转、褶皱)和脆性变形(线性结构、支撑结构、断层)微观结构和构造. 两种变形结构的存在是碎屑物质在形成过程中其含水量波动情况的反映. 冰下碎屑物质是冰下融出、滞碛作用的共同产物. 在整个冰下碎屑物质形成与变形过程中, 由于冰下水系季节性变化带来的冰岩界面上冰川融水含量的波动起了决定性作用.

关键词: 海螺沟冰川, 冰下融水, 冰下变形, 冰下过程

Abstract: The glacier dynamics at the ice-bed interface form an important element of the glacier system. Hailuogou Glacier is located in a warm and humid environment with maritime characteristics. The bottom of the glacier rich in debris slides intensively and the temperature at the bottom approaches the pressure melting point. Therefore, research on subglacial environment of this glacier makes a significant sense. We have sampled a sequence of subglacial deposits in the shallow eroded depression on the polished surfaces of Hailuogou Glacier. The investigated site provides evidence of sediment deposition and deformation to understand subglacial processes. We used an integrated approach to demonstrate a subglacial deposition and deformation model based on field observation and laboratory analysis. The results of grain-size, geochemical and SEM analyses testify each other that the source materials of the subglacial deposits are derived mainly from the glacier basal layer. Micromorphological work reveals that the subglacial deposits exhibits a range of ductile deformation microstructures (rotation structures, folding structure) and brittle deformation ones (lineation, edge-to-edge crushing and grain stacking, faulting structure). A subglacial deposition model has been established and the model exhibits a complex process including subglacial meltwater deposition, lodging. Sediment deposition and deformation is controlled by fluctuations in basal-water pressure, which determine changes in subglaciall meltwater drainage. Therefore subglacial meltwater at the ice-bed interface plays an important role in glacier dynamics, glacier deformation and sediment deposition processes. The maritime feature of Hailouogou Glacier examines this well.

Key words: Hailuogou Glacier, subglacial meltwater, subglacial deformation, subglacial processes

中图分类号:

P512.4+2

张梅, 崔之久, 刘耕年, 陈艺鑫, 聂振宇, 傅海荣. 青藏高原东南部贡嘎山海螺沟冰川冰下沉积物形成与变形[J]. 冰川冻土, 2013, 35(5): 1143-1155.

ZHANG Mei, CUI Zhi-jiu, LIU Geng-nian, CHEN Yi-xin, NIE Zhen-yu, FU Hai-rong. Formation and Deformation of Subglacial Deposits of Hailuogou Glacier in Mt. Gongga, Southeastern Tibetan Plateau[J]. JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY, 2013, 35(5): 1143-1155.

参考文献

[1] Huang Maohuan. Recent progresses in studies of ice flow in China [J]. Journal of Glaciology and Geocryology, 1995, 17(4): 366-370. [黄茂桓. 近年来我国冰流动研究进展[J]. 冰川冻土, 1995, 17(4): 366-370.]
[2] Boulton G S, Dobbie K E, Zatsepin S. Sediment deformation beneath glaciers and its coupling to the subglacial hydraulic system[J]. Quaternary International, 2001, 86: 3-28.
[3] Clarke G K C. Subglacial processes[J]. Annual Review of Ea-rth and Planetary Sciences, 2005, 33: 247-276.
[4] Piotrowski J A, Larsen N K, Menzies J, et al. Formation of subglacial till under transient bed conditions: Deposition, deformation, and basal decoupling under a Weichselian ice sheet lobe, central Poland [J]. Sedimentology, 2006, 53: 83-106.
[5] Liu Gengnian, Luo Risheng, Cao Jun, et al. Processes and environmental significance of the subglacial chemical deposits in Tianshan Mountains [J]. Science in China (Series D: Earth Sciences), 2005, 48(9): 1470-1478.
[6] Larsen N K, Piotrowski J A, Christoffersen P, et al. Formation and deformation of basal till during a glacier surge;Elisebreen, Svalbard[J]. Geomorphology, 2006, 81: 217-234.
[7] van der Meer J J M. Microscopic evidence of subglacial deformation[J]. Quaternary Science Reviews, 1993, 12: 553-587.
[8] van der Meer J J M. Particle and aggregate mobility in till: Microscopic evidence of subglacial processes[J]. Quaternary Science Reviews, 1996, 16: 827-831.
[9] Hart J K. An investigation of subglacial processes at the microscale from Briksdalsbreen, Norway[J]. Sedimentology, 2006, 53: 125-146.
[10] Menzies J, van der Meer J J M, Rose J. Till-as a glacial"tectomict", its internal architecture, and the development of a "typing" method for till differentiation [J]. Geomorphology, 2006, 75: 172-200.
[11] Denis M, Guiraud M, Konaté M, et al. Subglacial deformation and water-pressure cycles as a key for understanding ice stream dynamics: evidence from the Late Ordovician succession of the Djado Basin (Niger)[J]. International Journal of Earth Sciences, 2010, 99: 1399-1425.
[12] Phillips E, van der Meer J J M, Ferguson A. A new 'microstructural mapping' methodology for the identification, analysis and interpretation of polyphase deformation within subglacial sediments[J]. Quaternary Science Reviews, 2011, 30: 2570-2596.
[13] Su Zhen, Shi Yafeng, Zheng Benxing. Quaternary glacial remains on the Gongga Mountain and the division of glacial period [J]. Advances in Earth Sciences, 2002, 17(5): 639-647. [苏珍, 施雅风, 郑本兴. 贡嘎山第四纪冰川遗迹及冰期划分[J]. 地球科学进展, 2002, 17(5): 639-647.]
[14] Xie Zichu, Su Zhen, Shen Yongping, et al. Mass balance and water exchange of Hailuoguo Glacier in Mount Gongga and their influence on glacial melt runoff[J]. Journal of Glaciology and Geocryology, 2001, 23(1): 7-15. [谢自楚, 苏珍, 沈永平, 等. 贡嘎山海螺沟冰川物质平衡、水交换特征及其对径流的影响[J]. 冰川冻土, 2001, 23(1): 7-15.]
[15] Fan Wenji. The geological tectonic foundation of Minya Go-ngkar and its characteristic glacial landforms[J]. Journal of Chengdu University of Science and Technology, 1982(3): 19-33. [范文纪. 贡嘎山的地质构造基础和冰川地貌特征[J]. 成都科技大学学报, 1982(3): 19-33.]
[16] Liu Gengnian, Chen Yixin, Zhang Yue, et al. Mineral deformation and subglacial processes on ice-bedrock interface of Hailuogou Glacier[J]. Chinese Science Bulletin, 2009, 54(18): 3318-3325.
[17] Petschick R, Kuhn G, Gingele F. Clay mineral distribution in surface sediments of the South Atlantic: Sources, transport, and relation to oceanography[J]. Marine Geology, 1996, 130: 203-229.
[18] Xie Youyu. Surface Textural Features Micrographs of Chinese Quartz Sand [M]. Beijing: China Ocean Press, 1984. [谢又予. 中国石英砂表面结构特征图谱[M]. 北京: 海洋出版社, 1984.]
[19] Zhang Mei, Chen Yixin, Yin Senlu, et al. Sedimental features and paleo-environment reconstruction of the slope deposit at Xiaogangou of the Golmud River[J]. Arid Land Geography, 2011, 34(6): 890-903. [张梅, 陈艺鑫, 银森录, 等. 格尔木河小干沟坡积沉积特征与古环境重建[J]. 干旱区地理, 2011, 34(6): 890-903.]
[20] Mahaney W C, Claridge G, Campbell I. Microtextures on quartz grains in tills from Antarctica[J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 1996, 121: 89-103.
[21] Helland P E, Holmes M A. Surface textural analysis of quartz grains from ODP Site 918 off the southeast coast of Greenland suggests glaciation of southern Greenland at 11 Ma[J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 1997, 135: 109-121.
[22] Strand K, Passchier S, Nsi J. Implications of quartz grain microtextures for onset Eocene/Oligocene glaciation in Prydz Bay, ODP Site 1166, Antarctica [J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2003, 198: 101-111.
[23] Folk R L. A review of grain size parameters [J]. Sedimentology, 1966, 6: 73-93.
[24] Boulton G. Boulder shapes and grain size distribution of debris as indicators of transport paths through a glacier and till genesis [J]. Sedimentology, 1978, 25(6): 773-799.
[25] Haldorsen S. Grain-size distribution of subglacial till and its relation to glacial crushing and abrasion[J]. Boreas, 1981, 10: 91-105.
[26] Nesbitt H W, Young G M, McLennan S M, et al. Effects of chemical weathering and sorting on the petrogenesis of siliciclastic sediments, with implications for provenance studies [J]. The Journal of Geology, 1996, 104(5): 525-542.
[27] McLennan S M. Weathering and global denudation[J]. Journal of Geology, 1993, 101(2): 295-303.
[28] Feng Lianjun, Chu Xuelei, Zhang Qirui, et al. CIA (chemical index of alteration) and its applications in the Neoproterozoic clastic rocks[J]. Earth Science Frontiers, 2003, 10(4): 539-544. [冯连君, 储雪蕾, 张启锐, 等. 化学蚀变指数(CIA)及其在新元古代碎屑岩中的应用[J]. 地学前缘, 2003, 10(4): 539-544.]
[29] Strand K, Immonen N. Dynamics of the Barents-Kara ice sheet as revealed by quartz sand grain microtextures of the late Pleistocene Arctic Ocean sediments[J]. Quaternary Science Reviews, 2010, 29: 3583-3589.
[30] Damiani D, Giorgetti G, Turbanti I M. Clay mineral fluctuations and surface textural analysis of quartz grains in Pliocene-Quaternary marine sediments from Wilkes Land continental rise (East-Antarctica): Paleoenvironmental significance [J]. Marine Geology, 2006, 226: 281-295.
[31] Rose N C, Hart J K. Subglacial combination in the deforming bed: Inferences from SEM analysis[J]. Sedimentary Geology, 2008, 203: 87-97.
[32] Mahaney W C. Quartz microtextures and microstructures owing to deformation of glaciolacustrine sediments in the northern Venezuelan Andes [J]. Journal of Quaternary Science, 2004, 19(1): 23-33.
[33] Iverso N R, Hooyer T S, Baker R W. Ring-shear studies of till deformation: Coulomb-plastic behaviour and distributed strain in glacier beds [J]. Journal of Glaciology, 1998, 44: 634-642.
[34] Evans D J A, Phillips E R, Hiemstra J F, et al. Subglacial till: Formation, sedimentary characteristics and classification[J]. Earth-Science Reviews, 2006, 78: 115-176.
[35] Piotrowski J A, Larsen N K, Junge F W. Reflections on soft subglacial beds as a mosaic of deforming and stable spots[J]. Quaternary Science Reviews, 2004, 23: 993-1000.
[36] Benn D I, Evans D J A. Glaciers and Glaciation [M]. London: Arnold, 1998.
[37] Liu Qiao, Liu Shiyin. Trace tests of englacial and subglacial drainage system evolution and a case study at the Hailuogou Glacier [J]. Journal of Glaciology and Geocryology, 2012, 34(5): 1206-1219. [刘巧, 刘时银. 冰内及冰下水系演化的示踪试验及其应用研究[J]. 冰川冻土, 2012, 34(5): 1206-1219.]
[38] Lesemann J-E, Alsop G I, Piotrowski J A. Incremental subglacial meltwater sediment deposition and deformation associated with repeated ice-bed decoupling: a case study from the Island of Funen, Denmark[J]. Quaternary Science Reviews, 2010, 29: 3212-3229.
[39] Clerc S, Buoncristiani J F, Guiraud M, et al. Depositional model in subglacial cavities, Killiney Bay, Ireland. Interactions between sedimentation, deformation and glacial dynamics [J]. Quaternary Science Reviews, 2012, 33: 142-164.
[40] Phillips E, Merritt J. Evidence for multiphase water-escape during rafting of shelly marine sediments at Clava, Inverness-shire, NE Scotland [J]. Quaternary Science Reviews, 2008, 27: 988-1011.