The Effective Elastic Thickness of Lithosphere in the Mid-West Pacific and Its Geological Significance
-
摘要: 中西太平洋海山区是太平洋板块上洋壳年龄最老、磁条带异常最复杂、海山分布最密集、地质构造最独特、构造活动最强烈的一个区域, 为探讨区内众多海山的构造成因, 以板块构造理论为指导运用弹性板挠曲理论计算了中西太平洋海山区岩石圈的有效弹性厚度.结果显示, 研究区的有效弹性厚度总体上表现为北西高南东低的趋势, 西边的麦哲伦海山链表现出南北低中间高的趋势, 东边的中太平洋海山群呈现出由西往东厚度递减的现象, 且这2个典型区域的岩石圈有效弹性厚度与现今法属玻利尼西亚群岛处的比较接近.据此推测它们是在白垩纪期间(约130~90 Ma)形成于现今法属玻利尼西亚群岛处的大规模热点群附近, 且受到了后期火山岩浆活动的改造作用.Abstract: The Mid-West Pacific region is featured with the oldest oceanic crust, the most complicated magnetic anomaly lineation, the densest seamounts, the most peculiar geological feature and the strongest tectonic activity. To research tectonic genesis of these intraplate seamounts, this paper calculates the effective elastic thickness of the lithosphere (Te) with the elastic plate flexure based on the plate tectonic theory in the Mid-West Pacific. As a whole, Te slowly drops from the northwest part to the southeast part in the region. Te of the MST is higher in the middle of the trail than that in the north and the south parts. Te of the MPM is higher in the west part of the mountains than that in the east part. Furthermore, Te of these two typical areas is close to that of the present French Polynesia region. Thus, these seamounts were formed by the large volcanism which was produced by several hotspots during Cretaceous in the present French Polynesia region. And then these seamounts underwent some tectonic activities.
-
Key words:
- Mid-West Pacific /
- elastic plate flexure /
- effective elastic thickness /
- tectonics /
- geophysics
-
表 1 模型计算中用到的参数
Table 1. Parameters used by the flexural model
参数 定义 值/单位 w(x) 板块挠曲 m D 挠曲刚度 N·m Te 有效弹性厚度 m ρw 海水密度 1 025 kg/m3 ρc 洋壳密度 2 800 kg/m3 ρm 地幔密度 3 330 kg/m3 g 重力加速度 9.82 m·s-2 E 杨氏模量 6.5×1010 Pa υ 泊松比 0.25 D=ETe3/12(1-υ2). 
下载: 导出CSV
表 2 剖面计算结果
Table 2. Calculation result of nine profiles
剖面 起点经度(°) 起点纬度(°) 终点经度(°) 终点纬度(°) Te(km) 均方根 剖面1 184.30 19.70 186.20 16.0 7 0.582 2 剖面2 182.20 19.50 179.70 16.8 6 0.444 3 剖面3 178.50 18.80 178.50 15.8 7 0.398 1 剖面4 176.33 22.34 176.63 13.6 11 0.507 8 剖面5 176.60 23.00 169.60 16.4 11 0.527 8 剖面6 151.00 21.20 149.00 19.1 15 0.842 7 剖面7 153.50 19.20 149.20 18.2 16 0.530 9 剖面8 154.00 17.90 150.50 15.3 14 0.765 9 剖面9 156.40 16.60 153.90 13.8 17 0.397 8
下载: 导出CSV
表 3 研究区各区块Te值
Table 3. Te of twelve blocks in the study region
区块 1 2 3 4 5 6 Te(km) 16.0 6.0 32.0 17.0 10.2 5.0 均方根 0.079 5 0.092 5 0.122 2 0.113 7 0.129 2 0.094 9 区块 7 8 9 10 11 12 Te(km) 17.0 6.5 8.5 16.0 15.0 10.0 均方根 0.091 4 0.099 5 0.081 5 0.089 4 0.118 2 0.052 6
下载: 导出CSV
表 4 中太平洋海山群7座海山的Te
Table 4. Te of seven seamounts in the Mid-Pacific Mountain
海山 经度(°) 纬度(°) Te(km) 均方根 Darwin 171.6 22.0 4.5 0.128 6 Heezen 173.8 21.2 4.0 0.265 0 Resolution 174.5 21.2 11.0 0.243 2 Stetson 176.1 19.6 8.0 0.178 3 Jacqueline 176.7 19.4 7.5 0.193 4 Allison 180.3 18.5 4.5 0.282 1 Renard 184.0 17.8 4.0 0.299 4
下载: 导出CSV
表 5 麦哲伦海山链6座海山的Te
Table 5. Te of six seamounts in the Magellan seamount trail
海山 经度(°) 纬度(°) Te(km) 均方根 Himu 151.78 21.50 7.5 0.115 3 Hemler 151.70 19.70 15.0 0.165 3 Vlinder 154.30 17.12 16.5 0.165 5 Pako 155.10 15.70 21.0 0.172 6 Ioah 155.90 14.15 23.0 0.182 4 Ita Mai Tai 156.70 13.00 19.0 0.215 1
下载: 导出CSV
表 6 研究区13座海山的ΔTe
Table 6. ΔTe of thirteen seamounts in the study region
海山 T1(Ma) T2(Ma) t(Ma) Te1(km) Te2(km) ΔTe(km) H1(m) H2(m) ΔH(m) Himu 160.78 119.67 41.11 ~17.3 10.0 7.3 -5 887.7 -6 938.1 1 050.4 Hemler 162.12 99.99 62.13 ~21.3 15.0 6.3 -5 815.7 -6 956.4 1 140.7 Vlinder 165.94 94.13 71.81 ~22.9 16.5 6.4 -5 909.4 -7 008.6 1 099.2 Pako 166.66 92.00 74.66 ~23.3 21.0 2.3 -6 194.3 -7 018.4 824.1 Ioah 162.97 86.50 76.47 ~23.6 23.0 0.6 -6 544.4 -6 968.1 423.7 Ita Mai Tai 159.93 116.90 43.03 ~17.7 19.0 -1.3 -6 296.4 -6 926.2 629.8 Darwin 152.46 119.00 33.46 ~15.6 4.5 11.1 -5 879.2 -6 821.6 942.4 Heezen 150.69 123.10 27.59 ~14.2 4.0 10.2 -5 155.8 -6 796.5 1 640.7 Resolution 150.33 127.60 22.73 ~12.9 11.0 1.9 -4 055.5 -6 791.4 2 735.9 Stetson 142.46 98.50 43.96 ~17.9 8.0 9.9 -3 802.5 -6 677.4 2 874.9 Jacqueline 138.69 98.50 40.19 ~17.1 7.5 9.6 -4 313.9 -6 621.8 2 307.9 Allison 124.87 101.20 23.67 ~13.1 4.5 8.6 -4 927.1 -6 411.0 1 483.9 Renard 119.76 88.50 31.26 ~15.1 4.0 11.1 -4 832.2 -6 330.2 1 498.0
下载: 导出CSV
表 7 研究区6座海山的古纬度研究情况(Wilson et al., 1998)
Table 7. Paleolatitude of six seamounts in the study region
平顶海山 年龄(Ma) 古纬度(°) Limalok Initiation ~57.5±2.5 10.80±2.50S Drowning ~48.0±2 8.15±2.75S Present 5.55N Wodejebato Initiation ~76±1 11.60±3.20S Drowning ~69±1 6.20±2.20S Present 11.90N MIT Initiation ~119±2 11.55±3.45S Drowning ~101±2 8.35±3.35S Present 27.30N Takuyo-Daisan Initiation ~118±2 4.80±3.50S Drowning ~111±2 3.40±3.50S Present 34.15N Allison Initiation ~111±2 13.00±3.30S Drowning ~99±2 11.75±3.25S Present 18.45N Resolution Initiation ~128±2 14.50±3.30S Drowning ~99±2 10.70±3.30S Present 21.35N
下载: 导出CSV
-
[1] Bechtel, T.D., Forsyth, D.W., Sharpton, V.L., et al., 1990. Variations in effective elastic thickness of the North American lithosphere. Nature, 343: 636-638. doi: 10.1038/343636a0 [2] Calmant, S., 1987. The elastic thickness of the lithosphere in the Pacific Ocean. Earth and Planetary Science Letters, 85: 277-288. doi: 10.1016/0012-821X(87)90038-0 [3] Calmant, S., Cazenave, A., 1987. Anormalous elastic thickness of the oceanic lithosphere in the South-Central Pacific. Nature, 328: 236-238. doi: 10.1038/328236a0 [4] Calmant, S., Francheteau, J., Cazenave, A., 1990. Elastic layer thickening with age of the oceanic lithosphere: a tool for prediction of the age of volcanoes or oceanic crust. Geophysical Journal International, 100 (1): 59-67. doi: 10.1111/j.1365-246X.1990.tb04567.x [5] Filmer, P.E., McNutt, M.K., Wolfe, C.J., 1993. Elastic thickness of the lithosphere in the Marquesas and Society Islands. J. Geophys. Res., 98(B11): 19565-19577. doi: 10.1029/93JB01720 [6] Forsyth, D.W., 1985. Subsurface loading and estimates of the flexural rigidity of continental lithosphere. J. Geophys. Res., 90(B14): 12623-12632. doi: 10.1029/JB090iB14p12623 [7] Fu, Y.T., Li, J.L., Zhou, H., et al., 2000. Comments on the effective elastic thickness of continental lithosphere. Geological Review, 46(2): 149-159 (in Chinese with English abstract). http://gji.oxfordjournals.org/cgi/ijlink?linkType=ABST&journalCode=geology&resid=28/6/495 [8] Goodwillie, A.M., Watts, A.B., 1993. An altimetric and bathymetric study of elastic thickness in the Central Pacific Ocean. Earth and Planetary Science Letters, 118(1-4): 311-326. doi: 10.1016/0012-821X(93)90175-9 [9] Heezen, B.C., Matthews, J.L., Catalano, R., et al., 1973. Western Pacific guyots. Init. Rpts. DSDP, 20: 653-723. [10] Karner, G.D., Steckler, M.S., Thorne, J.A., 1983. Long-term thermo-mechanical properties of the continental lithosphere. Nature, 304: 250-253. doi: 10.1038/304250a0 [11] Koppers, A.A.P., Staudigel, H., Wijbrans, J.R., et al., 1998. The Magellan seamounts trail: implications for Cretaceous hotspot volcanism and absolute Pacific plate motion. Earth and Planetary Science Letters, 163(1-4): 53-68. doi: 10.1016/S0012-821X(98)00175-7 [12] Kruse, S.E., Liu, Z.J., Naar, D.F., et al., 1997. Effective elastic thickness of the lithosphere along the Easter seamount chain. J. Geophys. Res., 102(B12): 27305-27317. doi: 10.1029/97JB02158 [13] McNutt, M.K., Fischer, K.M., 1987. The South Pacific superswell. In: Keating, B.H., Fryer, P., Batiza, R., et al., eds., Seamounts, islands, and atolls. Geophysical Monograph Series, American Geophysical Union, Washington, DC, 43: 25-43. [14] McNutt, M.K., Judge, A.V., 1990. The superswell and mantle dynamics beneath the South Pacific. Science, 248(4958): 969-975. doi: 10.1126/science.248.4958.969 [15] Menard, H.W., 1964. Marine geology of the Pacific. McGraw-Hill, New York. [16] Menard, H.W., McNutt, M., 1982. Evidence for and consequences of thermal rejuvenation. J. Geophys. Res., 87(B10): 8570-8580. doi: 10.1029/JB087iB10p08570 [17] Parsons, B., Sclater, J.G., 1977. An analysis of the variation of ocean floor bathymetry and heat flow with age. J. Geophys. Res., 82: 803-827. doi: 10.1029/JB082i005p00803 [18] Smith, W.H.F., Staudigel, H., Watts, A.B., et al., 1989. The Magellan seamounts: Early Cretaceous record of the South Pacific isotopic and thermal anomaly. J. Geophys. Res., 94(B8): 10501-10523. doi: 10.1029/JB094iB08p10501 [19] Walcott, R.I., 1970. Flexural rigidity, thickness, and viscosity of the lithosphere. J. Geophys. Res., 75(20): 3941-3954. doi: 10.1029/JB075i020p03941 [20] Watts, A.B., 1978. An analysis of isostasy in the world's oceans: 1. Hawaiian-Emperor seamount chain. J. Geophys. Res., 83(B12): 5989-6004. doi: 10.1029/JB083iB12p05989 [21] Watts, A.B., Bodine, J.H., Ribe, N.M., 1980. Observations of flexure and the geological evolution of the Pacific Ocean basin. Nature, 283: 532-537. doi: 10.1038/283532a0 [22] Watts, A.B., Cochran, J.R., 1974. Gravity anomalies and flexure of the lithosphere along the Hawaiian-Emperor seamount chain. Geophys. J.R. Astr. Soc., 38(1): 119-141. doi: 10.1111/j.1365-246X.1974.tb04112.x [23] Watts, A.B., Karner, G.D., Steckler, M.S., 1982. Lithospheric flexure and the evolution of sedimentary basins. Philosophical Transactions of the Royal Society of London, Series A, Mathematical and Physical Sciences, 305(1489): 249-281. doi: 10.1098/rsta.1982.0036 [24] Watts, A.B., Steckler, M.S., 1979. Subsidence and eustasy at the continental margin of eastern North America. In: Talwani, M., Hay, W., Ryan, W.B.F., eds., Deep sea drilling results in the Atlantic Ocean: continental margins and paleoenvironment. American Geophysical Union, Washington, DC, Maurice Ewing Series, (3): 218-234. [25] Wessel, P., 1993. A reexamination of the flexural deformation beneath the Hawaiian Islands. J. Geophys. Res., 98(B7): 12177-12190. doi: 10.1029/93JB00523 [26] Wilson, P.A., Jenkyns, H.C., Elderfield, H., et al., 1998. The paradox of drowned carbonate platforms and the origin of Cretaceous Pacific guyots. Nature, 392: 889-894. doi: 10.1038/31865 [27] Winterer, E.L., 1976. Bathymetry and regional tectonic setting of the line islands chain. In: Schlanger, S.O., Jackson, E.D., Boyce, R.E., et al., eds., Init. Repts of DSDP, 33: 731-747. [28] Yuan, B.Q., Yvette, H.P.D., Cheng, S.Y., et al., 2002. The estimation of the effective elastic thickness of the continental lithosphere and its geological significance. Acta Geoscientia Sinica, 23(3): 269-272 (in Chinese with English abstract). http://www.oalib.com/paper/1559456 [29] Zuber, M.T., Bechtel, T.D., Forsyth D.W., 1989. Effective elastic thicknesses of the lithosphere and mechanisms of isostatic compensation in Australia. J. Geophys. Res., 94(B7): 9353-9367. doi: 10.1029/JB094iB07p09353 [30] 付永涛, 李继亮, 周辉, 等, 2000. 大陆岩石圈有效弹性厚度研究综述. 地质论评, 46(2): 149-159. https://www.cnki.com.cn/Article/CJFDTOTAL-DZLP200002005.htm [31] 袁炳强, Yvette, H.P.D., 程顺有, 等, 2002. 大陆岩石圈有效弹性厚度的计算及其地质意义. 地球学报, 23(3): 269-272. https://www.cnki.com.cn/Article/CJFDTOTAL-DQXB200203016.htm -
点击查看大图
图(2) / 表(7)
计量
- 文章访问数: 3285
- HTML全文浏览量: 165
- PDF下载量: 72
- 被引次数: 0
