Magma Supply Dynamics at Slow Spreading Rates: South Atlantic at 26 Degrees South

这是测试中央或多个供应是否占主导地位的项目(例如，作为扩展速率的函数，或在区域上以相同的扩展速率)，通过对南纬26度的中大西洋海脊(MAR)一段绘制得很好的100公里长的缓慢扩张(35-40毫米/年)的样品进行实验室岩石学和地球化学研究，26度的S段是进行此类测试的理想路段，因为它沿轴线简单形态(许多MAR节段的典型)，没有热点影响，存在密集的海束、重磁数据，以及附近海山近距离轴向玄武岩样品的可获得性，样品的初步化学数据显示出明显的规律性和系统性的沿轴化学变化规律，表明继续进行更详细的岩石学和化学研究是合理的。玄武岩熔体提供给活跃的大洋中脊的%%-%%过程是当前的研究热点，因为熔体供应动力学在洋壳的形成中起着关键作用。巴蒂扎博士在缓慢扩散的脊轴上拥有一组重要的紧密排列的样本。这些结果将加深我们对缓慢扩张山脊上岩浆供应动力学的理解，并将有助于与快速扩张山脊的类似数据集进行比较。

This is a project to test whether central or multiple supply is dominant (e.g., as a function of spreading rate, or regionally at the same spreading rate), by carrying out a laboratory petrologic and geochemical study of closely-spaced (7 km) samples from a well-mapped 100 km-long segment of the slow spreading (35-40 mm/yr) Mid-Atlantic Ridge (MAR) at 26 degrees S. The 26 degrees S segment is ideal for such a test because of its simple along-axis morphology (typical of many MAR segments), the absence of hot spot influence, the existence of dense Seabeam, gravity, and magnetic data, and the availability of closely-spaced axial basalt samples an samples from nearby seamounts, Preliminary chemical data for the samples show remarkably regular and systematic patterns of along-axis chemical variations, indication that continued, more detailed petrologic and chemical studies are justified. %%% Process that supply basalt melt to active mid-ocean ridges are of current interest because melt supply dynamics play a key role in the formation of oceanic crust. Dr. Batiza possesses an important set of closely spaced samples at a slow spreading ridge axis. The results will improve our understanding of magma supply dynamics at a slow spreading ridge, and the data will be useful for comparison with similar data sets for fast- spreading ridges.