Environmental and tectonic controls on the evolution of Devonian reef complexes

现代珊瑚礁，如澳大利亚海岸的大堡礁，是环境变化的敏感指标。 在地球过去的历史中，类似的珊瑚礁也在其他时期蓬勃发展，这些现在被珊瑚礁化的珊瑚礁提供了古代海洋环境的宝贵记录。 礁灰岩和白云岩作为矿床的寄主和石油储层也具有经济价值。 泥盆纪时期（3.8亿至3.6亿年）的珊瑚礁在加拿大西部和澳大利亚西北部保存完好。 这些泥盆纪珊瑚礁记录了地球历史上的一个关键时期，当时盘古超大陆正在组装，全球温室和冰库气候盛行，海洋生物发生全球灭绝。 我的研究的主要目标是重建的泥盆纪生物礁演化的历史，在加拿大西部和澳大利亚西北部的多学科研究的礁台序列。 这一目标将通过以下方式实现：（1）详细检查台地沉积物和沉积模式;（2）利用化石和地球化学指标确定台地的沉积年龄;（3）将台地之间以及台地与盆地之间的沉积物进行对比;（3）记录暴露的珊瑚礁中形成的古土壤层和岩溶;（4）确定台地的沉积年龄。（4）检查富含有机物的岩石，这将提供有关营养水平的信息;（5）描述泥盆纪珊瑚礁中记录的大规模灭绝事件的变化。 将从加拿大西部和澳大利亚西北部选定的露头、采石场和岩心中收集观察结果和岩石样本，并将其与地球物理和显微镜数据以及化学分析相结合。 这种综合方法将使我们能够阐明海平面波动、地壳运动、沉积过程和沉积后蚀变的复杂相互作用，这些因素控制了泥盆纪珊瑚礁的结构和演变。 这项研究最终对了解珊瑚礁的性质、预测现代珊瑚礁的行为以及评估人类活动对这些敏感生态系统的影响具有重要意义。

Modern coral reefs, such as the Great Barrier Reef off the Australian coast, are sensitive indicators of environmental change.  Similar reefs also flourished during other times in the Earth's past history, and these now fossilized reefs provide a valuable record of ancient marine environments.  Reef limestones and dolostones are also of economic interest as hosts for mineral deposits and as petroleum reservoirs.  Reefs of Devonian age (380-360 million years old) are well preserved in western Canada and northwestern Australia.  These Devonian reefs provide a record of a critical time in the Earth's history when the Pangea supercontinent was being assembled, global greenhouse and icehouse climates prevailed, and global extinction of marine organisms occurred.  The primary objective of my research is to reconstruct the history of Devonian reef evolution in western Canada and northwestern Australia by means of a multi-disciplinary study of the reef platform successions.  This objective will be achieved by (1) detailed examination of platform deposits and patterns of sedimentation; (2) determining the depositional ages of the platforms using fossil and geochemical indicators; (3) correlating deposits between platforms and from platform-to-basin; (3) documenting ancient soil horizons and karst formed in exposed reefs; (4) examining organic-rich rocks, which will provide information about nutrient levels; and (5) characterizing the changes across the mass extinction events recorded in the Devonian reefs.  Observations and rock samples will be collected from selected outcrops, quarries and drill-cores in western Canada and northwestern Australia, and integrated with geophysical and microscopy data and chemical analyses.  This integrated approach will allow us to elucidate the complex interplay of sea-level fluctuations, movements of the earth's crust, sedimentation processes and post-depositional alteration that have controlled the architecture and evolution of the Devonian reefs.  This research ultimately has important implications for understanding the nature of reefs through time, for predicting the behaviour of modern reefs and for assessing the impact of human activity on these sensitive ecosystems.