Life on the rocks: biotic and abiotic alteration of modern and ancient oceanic crust

想象一下恐龙出现之前的世界，那时动植物还没有进化。在那里，火山产生了新的土地，并向无氧大气中喷出有毒气体。那时大陆刚刚形成，海洋里除了微小的单细胞生物几乎没有生命。但是有什么吃的呢？再看深一点。在海底深处岩石的裂缝和裂缝中，海水渗入岩石，就像一条营养公路。在这些深、暗、有水的地方发现了微生物，它们在玻璃状的熔岩上定居，并能从这种不太可能的食物来源中提取营养。熔岩在海底火山中不断喷发，这些火山在海底形成了山脉，就像棒球上的接缝一样。这些洋中脊是动态环境，在这里，地壳、上覆海洋和大气之间发生了具有全球意义的化学、生物和热通量。加热循环流体与海洋地壳之间的化学交换导致了海洋基底化学成分的重大变化。在洋脊轴线上形成的新洋壳和在俯冲带的旧壳与地幔的重新合并可能是板块构造旋回的最基本组成部分。这些过程控制着地球的地貌以及地壳和地幔的化学和热演化。提出的研究的指导原则是通过数十亿年的地球历史来研究海洋地壳的水-岩-微生物变化。这是一个新兴的领域，直到最近十年才被认识到。海底深处微生物活动的温度和深度限制尚待探索，但海底深处生物圈中发生的微生物活动可能对水-岩石反应期间的化学通量产生深远影响，并可能是地球和其他行星上生命发展的关键。

Picture a world before the dinosaurs when plants and animals hadn't evolved yet. Where volcanoes gave birth to new land and spewed toxic gases into an oxygen free atmosphere. Where the continents were just being born and where the oceans were almost free of life except for tiny single celled organisms. But what was there to eat? Look a little deeper. In the cracks and crevices of the rocks deep beneath the seafloor seawater seeps down into the rocks and acts like a nutrient highway. In these deep, dark, watery places microbes have been found that colonize glassy lavas and can extract nutrients from this unlikely food source. The lavas are continuously erupted at undersea volcanoes that form mountain chains beneath the sea like seams on a baseball. These mid-ocean ridges are dynamic environments where globally significant chemical, biological, and heat fluxes occur between the Earth's crust, overlying oceans, and atmosphere. Chemical exchange between heated circulating fluids and the oceanic crust leads to major changes in the chemical composition of the oceanic basement. The formation of new oceanic crust at ridge axes and the reincorporation of aged crust into the mantle at subduction zones are perhaps the most fundamental components of the plate tectonic cycle. These processes control the physiography of the Earth and the chemical and thermal evolution of the crust and mantle. The guiding principle of the proposed research is the investigation of water-rock-microbial alteration of oceanic crust through billions of years of Earth history. This is an emerging field that has only been recognized in the last decade. The temperature and depth limits of microbiological activity deep beneath the seafloor have yet to be explored, but microbial activity occurring in the submarine deep biosphere may have a profound impact on chemical fluxes during water-rock reactions and possibly hold the key to the development of life on the Earth and other planets.