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在地质历史时期,天然气水合物分解引发的海底滑坡在世界海域内广泛分布,著名的有挪威岸外Storegga滑坡、美国阿拉斯加北部Beaufort Sea陆坡滑坡、美国东海岸南卡罗来纳大陆隆上Cape Fear滑坡、巴西东北部大陆边缘的亚马逊扇、以及西地中海巴利阿里盆地中的巨浊积层等;天然气水合物分解引发的气候突变事件也多次发生,著名的有侏罗纪早托尔阶大洋缺氧事件(Early Toarcian OAE)、白垩纪阿普特阶大洋缺氧事件(Aptian OAE)、晚古新世极热事件(LPTM),以及第四纪间冰期全球变暖等。不论是在地质历史寒冷期由于静水压力快速降低,还是在地质历史温暖期由于底水变暖,都可能会造成天然气水合物失稳而发生分解,从而诱发海底滑坡(滑塌),释放巨量的甲烷进入大气导致全球气候剧变。天然气水合物分解引起的海底滑坡和气候突变事件,不仅可以发生在过去,也可能发生在将来,其影响都有可能是灾难性的。因此,我们在勘探开发天然气水合物的同时,也应对其环境效应进行深入研究,评价和权衡人类开发天然气水合物的利弊,以期把握天然气水合物资源效益和环境效应之间的平衡。
During geologic history, submarine landslides caused by the decomposition of natural gas hydrates are widely distributed throughout the world. The most famous are the Norwegian offshore Storegga landslide, the Beaufort Sea landslide in northern Alaska, the Cape Fear landslide in South Carolina on the east coast of the United States, Brazil The Amazon fan on the northeastern continental margin, and the huge turbid accumulation in the western Balearic basin of the Mediterranean Sea. The sudden climate change events triggered by the gas hydrate decomposition also occur frequently. The famous Jurassic Early Torso Oceanic Oxygen Early Toarcian OAE, Cretaceous Aptian Ocean anoxic event, Late Paleocene (LPTM), and global glacial warming during the Quaternary. Whether it is the rapid decrease of hydrostatic pressure during the geologic history cold period or the warming of bottom water in the geologic history warm period, it may cause the gas hydrate to destabilize and decompose, thus inducing submarine landslide (slump) and release huge amount The methane into the atmosphere led to the global climate change. Submarine landslides and catastrophic events caused by the breakdown of gas hydrates can be catastrophic not only in the past but also in the future. Therefore, while exploring and developing natural gas hydrate, we should conduct an in-depth study on its environmental effects and evaluate and weigh the pros and cons of human development of natural gas hydrates in order to grasp the balance between the resource benefits of natural gas hydrates and the environmental effects.