臺灣博碩士論文加值系統

緬甸位於印度與歐亞兩大陸塊碰撞帶的東緣，其境內最顯著的地質現象是南北走向的右移斷層Sagaing Fault。Sagaing fault往北和東喜瑪拉雅造山結(eastern Himalayan Syntaxis) 相接，向南與安達曼海(Andaman Sea)以及印尼的蘇門答臘斷層(Sumatra fault)相連，形成一系列碰撞擠壓－陸塊脫逸－海盆張裂的特殊環境。位於這個從擠壓到張裂環境的過渡帶上，緬甸在整個東南亞的新生代地體構造中扮演要角，是研究印度－歐亞板塊碰撞演化的關鍵地區。
本研究針對緬甸中部晚新生代火山岩的氬-氬定年結果顯示，Monywa地區與Popa火山的岩漿活動主要發生在兩個時期:中新世中期與更新世。其中，Popa火山的定年結果為13.25 ± 0.07 Ma和13.27 ± 0.10 Ma，比前人依地層層序推估的上新世年代早很多。Monywa地區的定年結果則為15.46 ± 0.08 Ma，同屬於中新世中期岩漿活動的產物。
緬甸晚新生代火山岩屬於高鉀鈣鹼系列，中新世的火山岩以安山岩(SiO2 = 53.2 ~ 61.2 wt%)為主，更新世組成則以玄武岩到玄武岩質安山岩(SiO2 = 44.1 ~ 56.4 wt%)為主。其中Monywa地區部份更新世火山岩屬於鉀玄岩系的白榴基玄武岩(absarokite)，具有極為富集的輕稀土元素，其高鎂(Mg# = 70.6 ~ 73.6)及低矽含量(SiO2 ≈ 45 wt%)的特徵顯示它們是原始岩漿，可由富集的含角閃石地函橄欖岩經小程度部份熔融(~ 5 %)而形成。Popa火山的更新世火山岩以玄武岩為主(SiO2 = 47.6 ~ 56.4 wt%)，具有富集的輕稀土元素，它們的鎂值雖低(Mg# = 51.5 ~ 60.7)，但都沒有銪元素負異常的出現。相對地，Monywa地區與Popa火山的中新世火山岩較酸性(SiO2 = 53.2 ~ 61.2 wt%)，低鎂值(Mg# = 26.0 ~ 59.2)，但具有明顯的銪元素負異常，代表經歷了強烈的斜長石結晶分化作用。在不相容元素的分布上，所有緬甸晚新生代火山岩都具有大離子半徑元素的富集以及高場力鍵結元素虧損的現象，為隱沒帶或活動大陸邊緣島弧火成岩的地球化學特徵。在鍶-釹同位素組成上，它們則具有高的釹同位素(εNd = +1 ~ +4)以及低的鍶同位素值(87Sr/86Sr ≈ 0.7045)，沒有明顯的地殼物質或隱沒沉積物混染的情形。緬甸晚新生代火山岩的鍶-釹同位素組成分布範圍相當均一，顯示岩漿源區具有非常相似的同位素組成。
根據Sagaing fault的右移速率(20 ~ 50 mm/yr)，推估在13 Ma時，緬甸火成岩區位於目前的南邊約260~650公里處，因為當時印度洋板塊的隱沒作用，造成以安山岩為主的島弧岩漿。隨後，Sagaing fault的活動而帶動的安達曼海張裂，改變了這個區域的構造環境，可能使得火山活動停息。直到~ 1 Ma，緬甸陸塊幾乎已達現今的位置，而在Sagaing fault活動所主導的地體背景下，形成局部拉張的環境，使得富集的岩石圈地函或殘存的地函楔產生小程度部分熔融，重新開始了這個地區新的岩漿活動。

Burma is located in the eastern margin of the India-Asia collision zone. The most significant geologic feature in the region is arguably the Sagaing Fault, representing a dextral strike-slip fault system that links the eastern Himalayan Syntaxis in the north and the Andaman Sea in the south. This region is situated in a unique and “transitional” position between contractional (Himalayan) and extensional (Andaman Sea) tectonic settings, and furthermore characterized by the eruption of a series of Middle Miocene to Quaternary volcanoes along the Sagaing Fault. Here we report geochemical and Sr-Nd isotopic analyses of these young volcanic rocks from Mt. Popa and Monywa areas, Central Burma.
This study carried out Ar-Ar dating of some early stage of volcanic eruptions in the region. New Ar-Ar age results indicate two distinct stages of the volcanism, in mid-Miocene and Pleistocene, respectively. Two andesites from Mt. Popa yielded Ar-Ar ages of 13.25 ± 0.07 Ma and 13.27 ± 0.10 Ma, significantly older than previous conception of Pliocene ages. A drilled basalt from Monywa area yielded Ar-Ar age of 15.46 ± 0.08 Ma, which is broadly coeval with the mid-Miocene eruption in Mt. Popa volcano.
All the Burmese volcanic rocks show a potash-rich nature, with most of Mt. Popa samples (21 out of 25 analyses) plotting in the high-K calc-alkaline suite and Monywa samples (5 out of 8 analyses) in the shoshonitic suite. Some of the latter, specifically, resemble absarokite in terms of mineral constituents and trace element characteristics. All these rocks display significant depletions in the high field strength elements (HFSE; e.g., Nb, Ta and Ti), enrichments in the large ion lithophile elements (LILE; e.g., Cs, Rb, Ba) and light rare earth elements (LREE; e.g., La and Ce). Their overall incompatible trace element distribution patterns are similar to those of arc magmas formed in the subduction zone. Moreover, the Burmese rocks show a rather uniform isotopic composition, marked with high Nd (εNd = +4 to +1) and low Sr (87Sr/86Sr ≈ 0.7045) isotopic ratios. Consequently, we propose that the magma source of the high-K calc-alkaline rocks from Mt. Popa is the remnant and juvenile mantle wedge in the region despite the Indian Ocean slab beneath this part of the South Asia continent has already ceased its subduction. Under this framework, the Monywa shoshonites/absarokites represent products of small-degree melting (~5%) of a amphibole-bearing peridotite source in the mantle wedge.
Our results bear some implications for regional tectonic evolution. Given the dextral slip rate of ~20-50 mm/yr observed in the Sagaing fault, Mt. Popa volcano that erupted andesites at ~ 13 Ma was located ~250-600 km south of it present location as the result of the Indian Ocean slab’s subduction. Then, the volcanism may have become dormant owing to the active Sagaing fault and the Andaman Sea opening that eventually transformed the controlling tectonic force of the region from subduction to strike-slip. At ~ 1 Ma, when Mt. Popa nearly arrived to the present location, volcanism was renewed via small-degree melting of the remnant, enriched mantle wedge due probably to a trans-tension setting affiliated with regional tectonic transition.

國立台灣大學碩士學位論文口試委員會審定書..................i
中文摘要.................................................ii
英文摘要.................................................iv
表目.....................................................ix
圖目......................................................x
1 第一章 緒論............................................1
1.1 研究動機及目的...................................1
1.1.1 研究動機....................................1
1.1.2 研究目的....................................1
1.2 研究區域地質背景.................................3
1.2.1 Monywa地區................................5
1.2.2 Popa火山地區...............................5
1.2.3 騰沖地區....................................5
2 第二章 研究方法........................................8
2.1 標本採集及野外考察...............................8
2.1.1 Monywa地區................................8
2.1.2 Popa火山地區...............................8
2.2 岩石薄片製作.....................................9
2.3 全岩主要元素含量分析.............................9
2.3.1 主要元素含量分析............................9
2.3.2 燒失量測量.................................10
2.4 全岩微量元素含量分析............................10
2.4.1 微量元素含量分析...........................10
2.4.2 儀器分析之精度及準度.......................11
2.5 全岩鍶—釹同位素分析............................15
2.5.1 標本前製處理...............................15
2.5.2 鍶—釹同位素化學分離流程...................15
2.5.2.1 第一分離柱...........................18
2.5.2.2 鍶純化分離柱.........................18
2.5.2.3 第二分離柱...........................18
2.5.3 標準樣測量結果..............................19
2.5.3.1 鍶標準樣.............................19
2.5.3.2 釹標準樣.............................20
2.6 氬-氬定年分析....................................22
2.6.1 標本前製處理...............................22
2.6.2 標本分析流程...............................22
3 第三章 分析結果.......................................24
3.1 岩石薄片觀察....................................24
3.1.1 Monywa地區...............................24
3.1.2 Popa火山地區..............................24
3.2 定年結果........................................25
3.3 全岩主要元素....................................30
3.4 全岩微量元素....................................37
3.4.1 稀土元素...................................37
3.4.2 不相容元素.................................45
3.5 鍶-釹同位素......................................46
4 第四章 地球化學特徵與岩石成因.........................51
4.1 地球化學特徵隨時間之變化........................51
4.1.1 中新世火山活動.............................51
4.1.2 更新世火山活動.............................53
4.2 岩漿源區之性質..................................56
4.2.1 含水流體的影響.............................56
4.2.2 岩漿源區之性質.............................58
4.3 岩石成因........................................59
4.3.1 中新世時期.................................59
4.3.2 更新世時期.................................59
4.4 大地構造演化隱示................................60
5 第五章 結論...........................................62
參考文獻.................................................64
致謝.....................................................70

Barley, M. E., Pickard, A.L., Khin, Zaw, Rak, P. and Doyle, M.G., 2003, Jurassic to Miocene magmatism and metamorphism in the Mogok metamorphic belt and the India-Eurasia collision in Myanmar. Tectonics, doi: 10.1029/ 2002TC001398.
Bender, F., 1983, Geology of Burma. G. B., Berlin, 293p.
Bertrand, G., Rangin, C., Maury, R., Htun, H.M., Bellon, H. and Guillaud, J.P., 1998, The Singu basalt (Myanmar): new constraints for the amount of recent offset on the Sagaing Fault. Earth & Planetary Sciences, 327, 479-484.
Bertrand, G., Rangin, C., Maluski, H., Han, T.A., Thein, M., Myint, O., Maw, W. and Lwin, S., 1999, Cenozoic metamorphism along the Shan scarp (Myanmar): Evidence for ductile shear along the Sagaing fault or northward migration of the eastern Himalayan syntaxis?. Geophysical research letters, 26, 915-918.
Bertrand, G., Rangin, C., Maluski, H., Bellon, H. and the GIAC Scientific Party, 2001, Diachronous cooling along the Mogok metamorphic belt(Shan scarp, Myanmar): The trace of the northward migration of the Indian syntaxis. Journal of Asian Earth Sciences, 19, 649-659.
Bertrand, G. and Rangin, C., 2003, Tectonics of the western margin of the Shan plateau (central Myanmar): implication for the India-Indochina oblique convergence since the Oligocene. Journal of Asian Earth Sciences, 21, 1139-1157.
Chung, S.L., Chu, M.F., Zhang, Y., Xie, Y., Lo, C.H., Lee, T.Y., Lan, C.Y., Li, X., Zhang, Q. and Wang, Y., 2005, Tibetan tectonic evolution inferred from spatial and temporal variations in post-collisional magmatism. Earth- Science Reviews, 68, 173-196.
Curray, J.R., 2005, Tectonics and history of the Andaman Sea region. Journal of Asian Earth Sciences, 25, 187-232.
Eggins, S.M., Woodhead, J.D., Kinsley, L.P.J., Mortimer, G.E., Sylvester, P., McCulloch, M.T., Hergt, J.M. and Handler, M.R., 1997, A simple method for the precise determination of ≧ 40 trace elements in geological samples by ICPMS using enriched isotope internal standardization. Chemical Geology, 134, 311-326.
Foley, S. and Peccerillo, A., 1992, Potassic and ultrapotassic magmas and their origin. Lithos, 28, 181-185.
Furman, T., and Graham, D., 1999, Erosion of lithospheric mantle beneath the East African Rift system: Geochemical evidence from the Kivu volcanic province. Lithos, 48, 237-262.
Gill, J.B., 1981, Orogenic andesite and plate Tectonics. Springer, Berlin, 390p.
Goldstein, S.L., O''Nions, R.K. and Hamilton, P.J., 1984, A Sm-Nd study of atmospheric dusts and particulates from major river systems. Earth and Planetary Science Letters, 70, 221-236.
Govindaraju, K., 1994, 1994 compilation of workimg values and sample description for 383 geostandards. Geostandard Newsletter, 18(Special issue), 158.
Halliday, A.H., Lee, D.C., Tommasini, S., Davies, G.R., Paslick, C.R., Fitton, J.G. and James, D.E., 1995, Incompatible trace elements in OIB and MORB and source enrichment in the sub-oceanic mantle. Earth and Planetary Science Letters, 133, 379-395.
Handley, H.K., Macpherson, C.G., Davidson, J.P., Berlo, K. and Lowry, D., 2007, Constraining fluid and sediment contributions to subduction-related magmatism in Indonesia: Ijen Volcanic Complex. Journal of Petrology, 48, 1155-1183.
Harland, W.B., 1971, Tectonic transpression in Caledonian Spitzbergen. Geological Magazine, 108, 27-42.
Hutchison, C.S., 1989, Geological Evolution of South-east Asia, C. P., Oxford, 368p.
Iddings, J.P., 1895, Absarokite-shoshonite-banakite series. Journal of Geology, 3, 935-959.
Le Maitre, R.W., Bateman, P., Dudek A., Keller, J., Lameyre Le Bas, M.J, Sabine, P.A., Schmid, R., Sorensen, H., Streckeisen, A., Woolley, A.R. and Zanettin, B., 1989, A classification of igneous rocks and glossary of terms. Blackwell, Oxford, 193p.
Lee, H.Y., Chung, S.L., Wang, J.R., Wen, D.J., Lo, C.H., Yang, T.F., Zhang, Y., Xie, Y., Lee, T.Y., Wu, G. and Ji, J., 2003, Miocene Jiali faulting and its implications for Tibetan tectonic evolution. Earth and Planetary Science Letters, 205, 185-194.
Lo, C.H. and Lee, C.J., 1994, 40Ar/39Ar method of K-Ar age determination of geological samples using Tsing-Hua Open-Pool (THOR) reactor. Journal of the Geological Society of China, 37, 143-164.
Maury, R.C., Pubellier, M., Rangin, C., Wulput, L., Cotton, J., Socquet, A., Bellon, H., Guillaud, J.P. and Htun H.M., 2004, Quaternary calc-alkaline and alkaline volcanism in an hyper-oblique convergence setting, central Myanmar and western Yunnan. Bulletin de la Société géologique de France, 175, 461-472.
McDermott, F. and Hawkesworth, C.J., 1991, Th, Pb and Sr isotopic variations in young island arc volcanics and oceanic sediments. Earth and Planetary Science Letters, 104, 1-15.
McDonough, W.F., Sun, S.S., Ringwood, A.E., Jagoutz, E. and Hofmann, A.W., 1992, Potassium, rubidium, and cesium in the Earth and Moon and the evolution of the mantle of the Earth. Geochimica et Cosmochimica Acte, 56, 1001-1012.
Middlemost, E.A.K., 1975, The basalt clan, Earth Science Reviews, 11, 337-364.
Mitchell, A.H.G., 1993, Cretaceous-Cenozoic tectonic events in the western Myanmar (Burma)-Assam region. Journal of the Geological Society, 150, 1089-1102.
Mitchell, A.H.G., Ausa, C.A., Deiparine, L., Tin Hlaing, Nyunt Htay, Aung Khine, 2004, The ModiTaung-Nankwe gold district, Slate belt, central Myanmar: mesothermal veins in a Mesozoic orogen. Journal of Asian Earth Sciences, 23, 321-341.
Mitchell, A.H.G., Myint Thein Htay, Kyaw Min Htun, Myint Naing Win, Thura Oo, Tin Hlaing, 2007, Rock relationships in the Mogok metamorphic belt, Tatkon to Mandalay, central Myanmar. Journal of Asian Earth Sciences, 29, 891-910.
Peccerillo, A. and Taylor, S.R., 1976, Geochemistry of Eocene calc-alkaline volcanic rocks from Kastamonu area, Northern Turkey. Contributions to Mineralogy and Petrology, 58, 63-81.
Rangin, C., Chamot-Rooke, N., Nielsen, C., Farcy, F., Sun, D. and Bourdon, E., 2001, Pull-apart basin history along the eastern Indian shear zone from Eocene to present. The Journal of Conference Abstracts, 6, 326.
Replumaz, A., Kárason, H., Van der Hilst, R.D., Besse, J. and Tapponnier, P., 2004, 4-D evolution of SE Asia’s mantle from geological reconstructions and seismic tomography. Earth and Planetary Science Letters, 221, 103-115.
Roger, N.W. Hawkesworth, C.J. and Mattey, D.P., 1987, Sediment subduction and the source of potassium in orogenic leucitites. Geology, 15, 451-453.
Stephenson, D. and Marshall, T.R., 1984, The petrology and mineralogy of Mt. Popa Volcano and the nature of the late-Cenozoic Burma Volcanic Arc. Journal of the Geological Society of London, 141, 747-762.
Sun, S.S. and McDonough W.F., 1989, Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. Geological Society Special Publication, 42, 313-345.
Tanaka, T., Togashi, S., Kamioka, H., Amakawa, H., Kagami, H., Hamamoto, T., Yuhara, M., Orihashi, Y., Yoneda, S., Shimizu, H., Kunimaru, T., Takahashi, K., Yanagi, T., Nakano, T., Fujimaki, H., Shinjo, R., Asahara, Y., Tanimizu, M. and Dragusanu, C., 2000, JNdi-1: a neodymium isotopic reference in consistency with LaJolla neodymium. Chemical Geology, 168, 279-281.
Tatsumi, Y., Hamilton, D.L. and Nesbitt, R.W., 1986, Chemical characteristics of fluid phase released from a subducted lithosphere and origin of arc magmas: evidence from high-pressure experiments and natural rocks. Journal of Volcanology and Geothermal Research, 29, 293-309.
Tatsumi, Y. and Koyaguchi, T., 1989, An absarokite from a phlogopite lherzolite source. Contributions to Mineralogy and Petrology, 102, 34-40.
Vigny, C., Rangin, C. and Socquet, A., 2003, Present-day crustal deformation around Sagaing Fault, Myanmar. Journal of Geophysical Research, 108, ETG 6-1-10.
Wang, K.L., Chung, S.L., O’Reilly, S.Y., Sun, S.S., Shinjo, R. and Chen, C.H., 2004, Geochemical constraints for the genesis of post-collisional magmatism and the geodynamic evolution of the northern Taiwan region. Journal of petrology, 45, 975-1011.
White, W.M. and Patchett, J., 1984, Hf-Nd-Sr isotopes and incompatible element abundances in island arcs: implications for magma origins and crust-mantle evolution. Earth and Planetary Science Letters, 67, 167-185.
Wyllie, P.J., 1981, Plate tectonics and magma genesis. Geologische Rundschau, 70, 128-153.
Xu, Y.G., Menzies, M.A., Thirlwall, M.F. and Xie, G.H, 2001, Exotic lithosphere mantle beneath the western Yangtze craton: Petrogenetic links to Tibet using highly magnesian ultrapotassic rocks. Geology, 29, 863-866.
从柏林、陳秋媛、張儒爰、吳根耀、徐平，1994，中國滇西騰沖新生代火山岩的成因，中國科學(B輯)，第24卷第四期，第441-448頁。
李寄嵎、蔡榮浩、何孝�琚B楊燦堯、鍾孫霖和陳正宏，1997，應用X光螢光分析儀從事岩石樣品之定量分析(I)主要元素，中國地質學會八十六年年會暨學術研討會論文摘要，第418-420頁。
林立虹，1995，中國東部蘇魯超高壓變質帶之熱定年學研究，國立台灣大學地質科學研究所碩士論文，共86頁。
林宜臻，2007，藏東南白堊紀至古新世花崗岩類與火山岩之地球化學及岩石成因，國立台灣大學地質科學研究所碩士論文，共81頁。
駱宜民，2003，台灣西部井下新生代玄武岩之地球化學特徵與岩石成因，國立台灣大學地質科學研究所碩士論文，共84頁。