DEPENDENCE OF RIDGE-AXIS MORPHOLOGY ON MAGMA SUPPLY AND SPREADING RATE
DEPENDENCE OF RIDGE-AXIS MORPHOLOGY ON MAGMA SUPPLY AND SPREADING RATE
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DOI：
10.1038/364706a0
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发表时间：
1993-08-19
期刊：
影响因子：
64.8
通讯作者：
CHEN, YJ
中科院分区：
文献类型：
--
作者：
MORGAN, JP;CHEN, YJ
为什么有些洋中脊轴的地形表现是中谷深1-2公里，宽15 - 30公里，而其他洋中脊轴高100-200米，宽1-2公里？在一般情况下，中谷存在于脊轴传播的一半率小于约20-25毫米yr-1，而轴向高点被发现在更快的传播脊1，2。最近的地壳成因模型3，纳入热液冷却和地壳增生的岩浆透镜的手段，同意以及轴向形态的扩展率依赖的观测1，2，轴向岩浆chamber 3，4和厚度的脊轴lithosphere 5，6。但也有几个显着的例外之间的相关性扩展速率和轴向形态，如雷克雅未克海脊，它扩展在10毫米yr-1，但有一个轴向高。在这里，我们表明，通过扩展参考文献3的模型，包括地壳厚度的变化，我们可以解释观测到的依赖轴向形态的地壳厚度和扩展速率。我们的研究结果表明，轴向形态的最终控制是在脊轴的热结构，这是一个函数的扩展速率和magmna供应。
WHY do some mid-ocean-ridge axes have as their topographic expression a median valley 1-2 km deep and 15 30 km wide, whereas others have an axial high 100-200 m high and 1-2 km wide? In general, median valleys exist at the axes of ridges spreading at half-rates less than approximately 20-25 mm yr-1, whereas axial highs are found at faster-spreading ridges1,2. A recent crustal genesis model3, incorporating hydrothermal cooling and crustal accretion by means of a magma lens, agrees well with observations of the spreading-rate dependence of axial morphology1,2, the depth of the axial magma chamber3,4 and the thickness of the ridge-axis lithosphere5,6. But there are several notable exceptions to the correlation between spreading rate and axial morphology, such as the Reykjanes Ridge, which spreads at 10 mm yr-1 but has an axial high. Here we show that by extending the model of ref 3 to include variations in crustal thickness, we can explain the observed dependence of axial morphology on crustal thickness and spreading rate. Our results suggest that the ultimate control on axial morphology is the thermal structure at the ridge axis, which is a function of both spreading rate and magmna supply.