小高加索山之剝蝕歷史與東安納托利亞高原之抬升機制

Exhumation History of the Lesser Caucasus and its Implication for Uplift of the Eastern Anatolia Plateau

陳震東(Chen-Tung Chen)

指導教授 ： 李元希

國立中正大學/理學院/地球與環境科學系應用地球物理與環境科學研究所/碩士(2014年)

摘要

高加索－伊朗－安納托利亞高原地區（簡稱CIA）為阿拉伯板塊向北移動，與歐亞大陸板塊碰撞形成的造山帶，由許多微地塊、島弧及增積岩體拼貼而成，兩板塊於碰撞前，曾存在新特提斯洋，此海洋約於早漸新世（～35 Ma）開始閉合，直到晚始新世至早中新世（35－24 Ma）之間完全消滅，並使兩板塊開始碰撞，而兩陸塊間之海洋沈積物約持續至中新世中期（～12 Ma），其後則致使CIA地區開始抬升，並伴隨著北安納托利亞斷層的形成及廣泛的年輕火山岩漿作用。
本研究主要針對亞美尼亞境內由北至南之侵入岩，進行鋯石鈾－鉛定年與鋯石、磷灰石的核飛跡定年及熱模擬，討論其冷卻與剝蝕歷史，進而探討東安那托利亞高原之抬升機制。
研究結果顯示，鋯石鈾－鉛年代主要為中生代（～150 Ma），而鋯石核飛跡年代主要為始新世（～42－32 Ma），磷灰石核飛跡年代則為新生代（～24－9.8 Ma）；利用磷灰石核飛跡長度進行了熱模擬，顯示始新世至中新世（40－10 Ma）為穩定的緩慢抬升，直至上新世（5 Ma）開始轉為快速抬升，快速冷卻年代與廣泛的區域火成岩年代近似，此可能導因於區域岩石圈的拆解作用，導致軟流圈上湧，造成區域性火山作用與抬升。

關鍵字

亞美尼亞 ； 東安納托利亞高原 ； 小高加索山 ； 核飛跡定年 ； 鈾鉛定年

並列摘要

The Lesser Caucasus, located on the Eastern Anatolia Plateau with 1500-2000 m high elevation, was resulted from the collision between the Arabian plate and Eurasia plate. Different models and initial timing have been proposed to infer the timing and mechanism of plateau building. Here we combined with U-Pb, zircon and apatite fission track dating of the Mesozoic to Eocene granite to reveal the exhumation history of the Lesser Caucasus. The U-Pb show it exist Mesozoic to Eocene granite intrusion in Lesser Caucasus. Most of the zircon fission track ages concentrate on 33-39 Ma which is similar to the Eocene back arc magmatism event and Eocene U-Pb ages. The zircon fission track ages are similar with U-Pb ages indicating that the Eocene magmatism is a shallow crust emplacement. The apatite ages range from ca. 10-23 Ma along the Lesser Caucasus Range and increase far away the Lesser Caucasus. The track length thermal modeling of apatite fission track shows the exhumation rate is lower from 33 to 5 Ma and started to increase from ca. 5 Ma to now. This is consistent with age-elevatiand data of fission track and timing of extensive magmatism events in Lesser Cascasus.

並列關鍵字

Armenia ； Eastern Anatolia Plateau ； Lesser Caucasus ； Fission track dating ； U-Pb dating

參考文獻

林俞青（2011），亞美尼亞及高加索造山帶火成岩的地球化學特性與岩石成因。國立臺灣大學理學院地質科學研究所碩士論文，共124頁。

Agard, P., Omrani, J., Jolivet, L., & Mouthereau, F. (2005). Convergence history across Zagros (Iran): constraints from collisional and earlier deformation. International Journal of Earth Sciences, 94(3), 401-419.

Allen, M., Jackson, J., & Walker, R. (2004). Late Cenozoic reorganization of the Arabia‐Eurasia collision and the comparison of short‐term and long‐term deformation rates. Tectonics, 23(2).

Angus, D. A., Wilson, D. C., Sandvol, E., & Ni, J. F. (2006). Lithospheric structure of the Arabian and Eurasian collision zone in eastern Turkey from S‐wave receiver functions. Geophysical Journal International, 166(3), 1335-1346.

Armstrong, P. A. (2005). Thermochronometers in sedimentary basins. Reviews in mineralogy and geochemistry, 58(1), 499-525.