Nonlinear processes in geochemical systems

在自然界中，非线性复杂系统经常被驱动远离平衡。这当然适用于生物，但也适用于许多化学反应发生在开放环境中的地球化学系统。这些系统可能受到确定性过程、随机强迫（表示环境与系统耦合的随机性质）或两者的驱动。利用分析和数值方法的结合，提出的研究目标是研究各种非平衡非线性地球化学系统，这些系统都由一条共同的线索联系在一起：它们构成了地球化学相关环境中非线性反应性输运现象的表现。更具体地说，我将有助于回答这些问题：“是什么原因导致许多矿床表现出复杂的空间模式，从而它们的化学成分沿着核心到边缘的剖面（振荡带）或跨越矿物集合（周期性沉淀）变化？”通过对这些模式的分析，我们能了解到这些矿床的成因条件吗？例如，我们能否建立古气候情景来解释东地中海沉积物中黄铁矿周期性降水带的存在？是什么地球化学过程导致了在北方森林中从航空照片中观察到的有趣的大型森林年轮图案的形成？”火山系统提供了地球化学复杂系统的其他例子，这些系统富含远离平衡的非线性过程。我将致力于解决以下问题：“岩浆系统中的气泡在剧烈喷发的发展中发挥了什么作用？”我们能否使用浮石氧化作为估算火山柱的温度历史和冷却速率（地质测速法）的代理？”

In nature, nonlinear complex systems are often driven far from equilibrium. This is certainly true of living beings, but it is also the case for many geochemical systems, where chemical reactions occur in open environments. These systems may be driven by deterministic processes, stochastic forcing (representing the random nature of the environment coupled to the system), or both. Using a combination of analytical and numerical methods, the goal of the proposed research is to investigate a variety of non-equilibrium nonlinear geochemical systems that all are linked by a common thread: they constitute manifestations of non-linear reactive transport phenomena in geochemically relevant settings. More specifically, I will contribute to answer these questions: "What causes many mineral deposits to exhibit complex spatial patterns, whereby their chemical composition varies along a core-to-rim profile (oscillatory zoning) or across a mineral aggregate (periodic precipitation)? What can we learn about the genesis conditions of these deposits from the analysis of these patterns? For instance, can we develop paleo-climatic scenarios that explain the presence of periodic precipitation bands of pyrite in sediments of the Eastern Mediterranean? What are the geochemical processes leading to the formation of the intriguing large forest rings patterns, observed in the boreal forest from aerial photographs?" Volcanic systems provide other examples of geochemical complex systems rich in far-from-equilibrium non-linear processes. I will contribute to address the following questions:" What is the role played by gas bubbles in magmatic systems in the development of violent eruptions? Can we use pumice oxidation as a proxy for estimating the temperature history and cooling rate of a volcanic plume (geospeedometry)?"