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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Temporal variation of oceanic spreading and crustal production rates during the last 180 My
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Temporal variation of oceanic spreading and crustal production rates during the last 180 My

机译：最近180 My期间海洋扩散和地壳生产率的时间变化

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摘要

We present a re-evaluation of seafloor spreading and generation rates, mainly based on a direct measurement of the remaining surfaces of oceanic crust and isochron lengths defined in the most recent isochron maps [J.Y. Royer, R.D. Mulller, L.M. Gahagan, L.A. Lawyer, C.L. Mayes, D. Nurmberg, J.G. Sclater, A global isochron chart, Tech. Rep. 117, Austin, Univ. of Tex. Inst. for Geophys., 1992; R.D. Muller, W.R. Roest, J.Y. Royer, L.M. Gahagan, J.G. Sclater, Digital isochrons of the world's ocean floor, J. Geophys. Res., 102 (1997), 3211-3214]. Our evaluation of the amount of oceanic crust per unit age {dA/dt} as a function of age, which can be expressed as dA/dt = C-o(1 -t/t(m)), is in fairly good agreement with previous determinations [J.G. Sclater, B. Parsons, C. Jaupart, Oceans and continents: similarities and differences in the mechanisms of heat loss, J. Geophys. Res.,86 (1981) 11,535-11,552; D.B. Rowley, Rate of plate creation and destruction: 180 Ma to present, Geol. Soc. Amer. Bull., 114 (2002) 927-9331, with C-o = 2.850 +/- 0.119 km(2) year(-1) and t(m)= 180.2 +/- 9.7 Ma. Dividing these dA/dt by the ridge lengths L, defined as the isochron length at each epoch allowed us to compute the evolution of global half-spreading rates. These have been roughly constant at 25.9 +/- 3.3 mm year(-1) for at least the last 150 Ma. We propose that the global seafloor surface generation rate is roughly constant as well, with a mean half-value of 1.298 +/- 0.284 km(2) year(-1) and varying +/-20% with time. This study corroborates the recent conclusion of Rowley [D.B. Rowley, Rate of plate creation and destruction: 180 Ma to present, Geol. Soc. Amer. Bull., 114 (2002) 927-933], of a constant generation rate since 180 Ma, and completely contradicts the commonly accepted idea of high seafloor spreading and surface generation rates during a large part of the Cretaceous. Combining the oceanic surface generation rates derived here with crustal thicknesses deduced from the chemical composition of old oceanic crusts and seismic measurements [E. Humler, C.H. Langmuir, V Daux, Depth versus age: new perspectives from the chemical compositions of ancient crust, Earth Planet Sci. Lett., 173 (1999) 7-23], the magmatic flux at young (0-80 Ma) oceanic ridges appears to be about 18.1 +/- 3.4 km(3) year(-1) and was possibly 15% to 30% higher during the Mesozoic. We propose that mantle temperature variation provides an alternative mechanism to spreading rate for the Cretaceous highstand in sea-level and atmospheric CO2 generation. (C) 2004 Elsevier B.V. All rights reserved.
机译：我们主要基于直接测量洋壳的剩余表面和最新等时线图中定义的等时线长度，对海底扩展和生成速率进行了重新评估。 Royer，R.D. Mulller，L.M. Gahagan，L.A. Lawyer，C.L. Mayes D.Nurmberg J.G. Sclater，全球等时线图，技术。 117号大学，奥斯汀德克萨斯大学的对于Geophys。，1992; R.D.穆勒（W.R. Roest），J.Y。 Royer，L.M. Gahagan，J.G. Sclater，《世界海底的数字等时线》，J。Geophys。 ，Res。102（1997），3211-3214]。我们对单位年龄{dA / dt}随年龄变化的洋壳数量的评估可以表示为dA / dt = Co（1-t / t（m）），与先前的研究相当吻合决定[JG Sclater，B。Parsons，C。Jaupart，海洋和大洲：热损失机理的异同，J。Geophys。 Res。，86（1981）11,535-11,552; D B。罗利（Rowley），板块形成和破坏的速率：180 Ma至今，Geol。 Soc。阿米尔。 Bull.114（2002）927-9331，C-o = 2.850 +/- 0.119 km（2）year（-1）和t（m）= 180.2 +/- 9.7 Ma。将这些dA / dt除以脊长L（定义为每个时期的等时线长度）可以使我们计算全局半扩展速率的演变。至少在最近的150 Ma内，这些值大致保持恒定在25.9 +/- 3.3毫米（-1）年。我们建议全球海底表面生成率也大致保持恒定，平均值为1.298 +/- 0.284 km（2）年（-1），并且随时间变化+/- 20％。这项研究证实了罗利[D.B.罗利（Rowley），板块形成和破坏的速率：180 Ma至今，Geol。 Soc。阿米尔。 [Bull。，114（2002）927-933]，自180 Ma以来一直保持恒定的发电速度，这与白垩纪大部分时期普遍认可的高海底扩散和地表发电速度的观点相矛盾。将此处得出的海洋表面生成速率与从旧海洋壳的化学成分和地震测量推导出的地壳厚度相结合[E.休勒（C.H.朗缪尔（Langmuir），佛多（V Daux），深度与年龄：从古代地壳化学组成的新视角“地球行星科学”。 Lett。，173（1999）7-23]，年轻（0-80 Ma）洋脊的岩浆通量似乎约为18.1 +/- 3.4 km（3）年（-1），可能为15％至30在中生代期间增加％。我们认为，地幔温度变化为海平面和大气CO2生成中白垩纪高架的扩散速率提供了一种替代机制。 （C）2004 Elsevier B.V.保留所有权利。

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