Cruise support for Dr Christopher Smith-Duque to sail as a Petrologist on IODP Expedition 344 - CRISP II

为 Christopher Smith-Duque 博士提供邮轮支持，以岩石学家身份参加 IODP 344 号远征 - CRISP II

• 批准号: NE/K00672X/1
• 负责人: Damon Teagle
• 金额: $ 0.47万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FK00672X%2F1
• 关键词: Cruise; support; Dr; Christopher; Smith

The subduction of tectonic plates is one of the fundamental processes of plate tectonics, and the most potent source of earthquakes near the Earth's surface. The process occurs at convergent boundaries where one tectonic plate moves under another tectonic plate sinking into the Earth's mantle. Despite the wealth of research that has been dedicated to understand the role of subduction in earthquake generation (seismogenesis) direct sampling of the seismogenic region of subduction zones has, until now been beyond the reach of direct sampling and observation.Integrated Ocean Drilling Program (IODP) Expedition 344 forms an integral part of an ambitious project to understand the processes that control the formation and rupture of large earthquakes at subduction zones. We will collect sediment and basement cores from 4 sites across the Central American margin offshore the Osa Peninsula of Costa Rica, spanning the area immediately preceding subduction through to the area above the seismogenic zone preparing the groundwork for a later expedition to drill and sample this zone.Aboard ship, I will be part of an international team of scientists using a multi-disciplinarily approach to characterise the geological nature of seafloor sediments, underlying volcanic rocks and accreted sediment and basement that make up the subducting oceanic plate (Cocos-Nazca) and the upper (Caribbean) plate of Costa Rica. The erosive Costa Rican subduction system is targeted since the majority of subduction systems are erosive (Upper plate material is eroded and drawn into subduction), it is an area of intense seismic (earthquake) activity, and crucially earthquake nucleation in this region occurs at a sufficiently shallow depth to be sampled by ocean drilling.IODP Expedition 344 will determine:1) The geological nature of subducting sediments and basement, including their composition, texture and physical properties.2) The rate of subduction of the oceanic plate and erosion of the upper plate of the Costa Rican subduction system3) The interactions between fluids and rock within the upper plate.4) How the forces acting on the subduction system change as the subduction system enters the seismogenic zone. My role as a petrologist on Expedition 344 will be to describe and characterise rocks of igneous origin that occur beneath the sediments of the subducting oceanic crust and within the upper plate basement. The volcanic material in the subducting plate and the upper plate originally formed millions of years ago at mid-ocean ridges and during back-arc volcanism respectively. Describing and analysing these rocks during Expedition 344 will allow me to infer the styles of the original eruptive processes and classify them.Thermally driven chemical processes known as hydrothermal alteration, results in the exchange of elements and compounds between seawater and rock to form new minerals 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. In the upper plate, basement of volcanic origin (e.g., accreted seamounts) may have been subjected to similar seafloor alteration processes prior to their emplacement. However, an additional consideration will be the chemical exchange processes that have taken place during accretion and during subduction, a potentially significant factor in how earthquakes form. I will interpret hydrothermal alteration features within igneous rock recovered during Expedition 344 to determine how seawater and subduction-related fluids interacted with oceanic basement and upper plate basement respectively. My work will contribute to our understanding of the hydrogeological system of the subduction zone which will help us to understand the setting at which earthquakes can form.

构造板块俯冲是板块构造的基本过程之一，也是地球表面附近地震的最大震源。这一过程发生在会聚边界，在那里一个构造板块在另一个构造板块下方移动，下沉到地幔中。尽管有大量研究致力于了解俯冲在地震孕育中的作用(地震成因)，但到目前为止，对俯冲带孕震区的直接采样一直超出了直接采样和观测的范围。综合大洋钻探计划(IODP)考察344是一个雄心勃勃的项目的组成部分，该项目旨在了解控制俯冲带大地震形成和破裂的过程。我们将从哥斯达黎加奥萨半岛近海中美洲边缘的4个地点收集沉积物和基底岩心，横跨俯冲前的区域，一直到地震孕育区上方的区域，为以后的探险钻探和采样该区域做准备。在船上，我将成为一个国际科学家团队的一员，他们使用多学科方法来描述海底沉积物、底层火山岩、吸积沉积物和基底的地质性质，它们构成了哥斯达黎加的俯冲海洋板块(Cocos-Nazca)和上层(加勒比海)板块。侵蚀性的哥斯达黎加俯冲系统之所以成为目标，是因为大多数俯冲系统都是侵蚀性的(上板块物质被侵蚀并被拉入俯冲)，它是一个强烈的地震(地震)活动区，关键是该地区的地震成核发生在足够浅的深度，可以通过海洋钻探进行采样。IODP探险344将确定：1)俯冲沉积物和基底的地质性质，包括它们的组成，结构和物理性质2)大洋板块的俯冲速率和哥斯达黎加俯冲系统上板块的侵蚀3)上板块内流体和岩石之间的相互作用4)当俯冲系统进入孕震带时，作用于俯冲系统的力是如何变化的。作为344探险队的一名岩石学家，我的角色将是描述和描述出现在俯冲洋壳沉积物之下和上板块基底内的火成岩。俯冲板块和上板块中的火山岩物质最初分别形成于数百万年前的大洋中脊和弧后火山活动期间。在344次探险中描述和分析这些岩石将使我能够推断出原始喷发过程的类型并对它们进行分类。被称为热液改造的热驱动化学过程导致海水和岩石之间的元素和化合物的交换，以在岩石碎片之间的空隙中、在冷却的裂缝中以及在被称为气泡的气泡中形成新的矿物，这些气泡曾经被喷发期间从岩浆中逸出的气体占据。在上板块，火山成因的基底(例如，海山)在就位之前可能经历了类似的海底改造过程。然而，另一个考虑因素将是在吸积和俯冲过程中发生的化学交换过程，这可能是地震形成的一个重要因素。我将解释在344探险中发现的火成岩中的热液蚀变特征，以确定海水和与俯冲相关的流体分别与大洋基底和上板块基底相互作用的方式。我的工作将有助于我们了解俯冲带的水文地质系统，这将有助于我们了解地震可能形成的背景。