Cruise support for Dr Christopher Smith-Duque, shipboard petrologist on IODP Expedition 329

世界上的海洋和海底是地球上勘探最少的区域。尽管覆盖了地球表面的70%以上，但目前只有几百个钻孔和疏浚点代表了我们对海底下的全部采样。与地球上任何其他地区相比，世界上最大的洋流系统南太平洋环流系统仍然缺乏采样。上一次从南太平洋这一地区的海底系统地回收物质的科学考察是在130多年前的HMS挑战者号考察期间（1872-1876）.综合大洋钻探计划第329次考察提供了一个独特的机会，可以发现海底下生命的性质和范围，并了解已经运作了超过20年的地质过程。在地球上最大的，最不发达的地区之一。JOIDES Resolution的断面将在66天内覆盖从塔希提岛帕皮提到新西兰奥克兰的11,000公里海洋，并将从7个地点收集沉积物岩心，并在3号船上钻入海洋地壳的玄武岩。我将成为一个国际科学家团队的一员，这是一个跨学科的方法，以确定在东太平洋海隆洋中脊形成的海底沉积物和下面的火山岩的地质和生物性质。南太平洋环流特别令人感兴趣，因为数百万年来，这里一直是海洋中生物活动极低的区域。IODP Expedition 329将确定：1）环流内海底下存在哪些生命（如果有的话）以及生命在哪些栖息地和条件下发生;（2）海洋在控制从环流中心到边缘的一个样带内的海底生境方面所起的作用。例如，近海面死亡生物量的积累如何影响海底生命; 3）海底沉积物和基底内不依赖光合作用过程的生命程度，以及4）海底下岩石的地质，以及不断演化的热驱动海水岩石的化学相互作用影响着海底的可居住性和生命的分布。作为329号探险队唯一的岩石学家，我的角色将是描述和解释海底的岩石。沉积物下面的火山岩这些玄武质熔岩是在东太平洋隆起南部的岩浆喷发过程中形成的，东太平洋隆起是形成太平洋基底的大洋中脊。这些熔岩已经冷却，这些地点在数百万年的时间里从活跃的山脊移动到现在的位置。通过对329号考察期间岩石的描述和分析，我可以推断熔岩喷发的类型，并对岩石类型进行分类。我的职责还包括描述和解释海水与海洋基底的相互作用以及海水-玄武岩热交换和化学交换的条件。新矿物是由热驱动的化学过程形成的，称为热液蚀变，在海水和岩石之间交换元素和化合物。这些新的矿物形成于岩石碎片之间的空隙中，冷却裂缝中以及被称为囊泡的气泡中，这些气泡曾经被火山喷发时从岩浆中逸出的气体占据。岩浆被海水快速冷却形成的火山玻璃也可以被替换，因为在熔岩缓慢冷却过程中形成的火成岩矿物也可以被替换。海水和玄武岩之间的许多反应释放出化学物质和能量，为原始微生物海底生命创造了潜在的栖息地。描述这些蚀变特征对于了解海洋基底内的生物定殖和生命的潜在范围是必不可少的。

The world's oceans and the seafloor are the most poorly explored regions of Earth. Despite covering over 70% of the Earth's surface, only a few hundred drilled holes and dredge sites currently represent the entirety of our sampling of the sub-seafloor. More so than any other region on Earth there remains a dearth of sampling in the South Pacific Gyre, the world's largest ocean current system. The last scientific expedition to systematically recover material from the ocean floor in this region of the South Pacific Ocean was over 130 years ago during the HMS Challenger Expedition (1872-1876).Integrated Ocean Drilling Program (IODP) Expedition 329 represents a unique opportunity to discover the nature and extent of life below the seafloor and to understand the geological processes that have operated for over 100 million years in one of the largest, most poorly explored regions of the Earth. The JOIDES Resolution's transect, will cover 11,000 km of ocean over a period of 66 days from Papeete, Tahiti to Auckland, New Zealand and will collect sediment cores from 7 sites and drill into the basalts of the oceanic crust at 3.Aboard ship, I will be part of an international team of scientists using a multi-disciplinary approach to characterise the geological and biological nature of seafloor sediments and the underlying volcanic rocks that formed at the East Pacific Rise mid-ocean ridges. The South Pacific Gyre is of particular interest because this has been a region of extremely low biological activity within the oceans for many millions of years.IODP Expedition 329 will determine: 1) What, if any, life occurs beneath the sea floor within the gyre and in what habitats and conditions does life occur; 2) The role the ocean plays in controlling habitats beneath the seafloor across a transect from the centre to the edge of the gyre. For example, how does the accumulation of dead biomass from near the surface affect life in the ocean floor; 3) The extent of life within sea floor sediment and basement that is independent of the photosynthetic process, and 4) How the geology of sub-seafloor rocks, and the evolving thermally driven seawater/rock chemical interactions affect the habitability of the seafloor and distribution of life.My role as the sole petrologist sailing on Expedition 329 will be to describe and characterise the volcanic rocks that occur beneath the sediments. These basaltic lavas formed during eruptions of magma at the southern East Pacific Rise, the mid-ocean ridges that has formed much of the Pacific Ocean basement. These lavas have since cooled and the sites moved over millions of years away from the active ridge to their present locations. Describing and analysing the rocks during Expedition 329 will allow me to infer the styles of lava eruptions and classify the rock types.My role will also include describing and interpreting how seawater interacts with oceanic basement and the conditions of seawater-basalt thermal and chemical exchange. New minerals are formed by thermally driven chemical process known as hydrothermal alteration that exchanges elements and compounds between seawater and rock. These new minerals form in voids between fragments of rock, in cooling fractures and within bubbles known as vesicles that were once occupied by gases escaping from the magmas during eruption. Volcanic glass formed by the very rapid quenching of magma by seawater can also be replaced as can the igneous minerals that were formed during the slower cooling of the lava. Many of the reactions between seawater and basalts release chemicals and energy that create potential habitats for primitive microbial sub-seafloor life. Describing these alteration features will be imperative for understanding the biological colonization and potential extent of life within oceanic basement.