下地幔 (地球)

下地幔 (地球)（英語：Lower Mantle (earth)）以前也被稱為地球中層，約佔地球總體積的 56%，位於地球表以下 660 至 2900 公里的區域；在過渡區和外核之間^[1]。根據初步地球參考模型（PREM)，下地幔分為三個部分，最上層（660-770公里）、中下地幔（770-2700公里）和D層（2700-2900公里）^[2]。下地幔的壓力和溫度範圍為 24-127 GPa^[2] 和 1900-2600 K. ^[3]。地幔岩被認爲是下地幔的主要成分^[4]。它包含三相鎂橄欖石(bridgmanite)、鐵方鎂石和矽酸鈣鈣鈦礦(calcium-silicate perovskite)。高壓在下地幔已被證明會引起含鐵錳礦和方鎂石的離子旋轉變化^[5]。這可能會影響地幔柱的動力學^[6]^[7],和下地幔的化學變化^[5]。

地震波速度和密度在下地幔的頂界，約660 公里（410 英里）深，有急劇增加現象)^[8]。在此深度，尖晶橄欖石 (ringwoodite )(γ-(Mg,Fe)₂SiO₄) 分解成布里奇曼石(Mg-Si perovskite) 和鐵質方鎂石(magnesiowüstite)^[8]。根據地震數據和高壓實驗室實驗資料，推論這個分解就造成上地幔和下地幔之間的界面。下地幔的底部，包括「D」區，與地核相鄰，深約2700公里^[8]。

參考文獻

^ Kaminsky, Felix V. (2017). The Earth's lower mantle: composition and structure. Cham: Springer. ISBN 9783319556840 OCLC 988167555
^ ^2.0 ^2.1 Dziewonski, Adam M.; Anderson, Don L. (1981). "Preliminary reference Earth model". Physics of the Earth and Planetary Interiors. 25 (4): 297–356. doi:10.1016/0031-9201(81)90046-7. ISSN 0031-9201.
^ Katsura, Tomoo; Yoneda, Akira; Yamazaki, Daisuke; Yoshino, Takashi; Ito, Eiji (2010). "Adiabatic temperature profile in the mantle". Physics of the Earth and Planetary Interiors. 183 (1–2): 212–218. doi:10.1016/j.pepi.2010.07.001. ISSN 0031-9201.
^ Ringwood, Alfred E. (1976). Composition and petrology of the earth's mantle. McGraw-Hill. ISBN 0070529329 OCLC 16375050
^ ^5.0 ^5.1 Badro, J. (2003-04-03). "Iron Partitioning in Earth's Mantle: Toward a Deep Lower Mantle Discontinuity". Science. 300 (5620): 789–791. doi:10.1126/science.1081311 ISSN 0036-8075 PMID 12677070 S2CID 12208090
^ Shahnas, M.H.; Pysklywec, R.N.; Justo, J.F.; Yuen, D.A. (2017-05-09). "Spin transition-induced anomalies in the lower mantle: implications for mid-mantle partial layering". Geophysical Journal International. 210 (2): 765–773. doi:10.1093/gji/ggx198. ISSN 0956-540X.
^ Bower, Dan J.; Gurnis, Michael; Jackson, Jennifer M.; Sturhahn, Wolfgang (2009-05-28). "Enhanced convection and fast plumes in the lower mantle induced by the spin transition in ferropericlase". Geophysical Research Letters. 36 (10). doi:10.1029/2009GL037706. ISSN 0094-8276.
^ ^8.0 ^8.1 ^8.2 Condie, Kent C. (2001). 'Mantle Plumes and Their Record in Earth History. Cambridge University Press. pp. 3–10. ISBN 0-521-01472-7

[”Kaminsky”-1] Kaminsky, Felix V. (2017). The Earth's lower mantle: composition and structure. Cham: Springer. ISBN 9783319556840 OCLC 988167555

[Dziewonski-2] 2.0 ^2.1 Dziewonski, Adam M.; Anderson, Don L. (1981). "Preliminary reference Earth model". Physics of the Earth and Planetary Interiors. 25 (4): 297–356. doi:10.1016/0031-9201(81)90046-7. ISSN 0031-9201.

[”Katsura”-3] Katsura, Tomoo; Yoneda, Akira; Yamazaki, Daisuke; Yoshino, Takashi; Ito, Eiji (2010). "Adiabatic temperature profile in the mantle". Physics of the Earth and Planetary Interiors. 183 (1–2): 212–218. doi:10.1016/j.pepi.2010.07.001. ISSN 0031-9201.

[”Ringwood”-4] Ringwood, Alfred E. (1976). Composition and petrology of the earth's mantle. McGraw-Hill. ISBN 0070529329 OCLC 16375050

[”Badro”-5] 5.0 ^5.1 Badro, J. (2003-04-03). "Iron Partitioning in Earth's Mantle: Toward a Deep Lower Mantle Discontinuity". Science. 300 (5620): 789–791. doi:10.1126/science.1081311 ISSN 0036-8075 PMID 12677070 S2CID 12208090

[”Shahnas”-6] Shahnas, M.H.; Pysklywec, R.N.; Justo, J.F.; Yuen, D.A. (2017-05-09). "Spin transition-induced anomalies in the lower mantle: implications for mid-mantle partial layering". Geophysical Journal International. 210 (2): 765–773. doi:10.1093/gji/ggx198. ISSN 0956-540X.

[”-7] Bower, Dan J.; Gurnis, Michael; Jackson, Jennifer M.; Sturhahn, Wolfgang (2009-05-28). "Enhanced convection and fast plumes in the lower mantle induced by the spin transition in ferropericlase". Geophysical Research Letters. 36 (10). doi:10.1029/2009GL037706. ISSN 0094-8276.

[”Condie”-8] 8.0 ^8.1 ^8.2 Condie, Kent C. (2001). 'Mantle Plumes and Their Record in Earth History. Cambridge University Press. pp. 3–10. ISBN 0-521-01472-7

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