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上扬子区北缘米仓山地区 3个宝塔组剖面的远岸水中浮游圆尾虫类三叶虫丰度变化研究表明 ,该区海域在兰维恩晚期至阿什极尔早期曾出现 4次海平面跌落和 3次海平面上升 ,与同期全球海平面变化有一定的可比性。证明圆尾虫类丰度变化的研究可能是揭示奥陶纪全球海平面变化规律的一个有效手段。
Studies on the abundance of trilobite in the offshore waters of the three pagodas in the Micangshan Formation on the northern margin of the Upper Yangtze region show that there were four Sea level drop and 3 sea level rise have certain comparability with global sea level change in the same period. It is possible that the study on the abundance changes of the circadian species may be an effective means of revealing the Ordovician global sea level changes.