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A quantitative reconstruction method of paleo-primary productivity is present on the basis of the investigation on the faunal record in cherts. By obtaining the accumulation rate of radiolarian shells in the cherts and considering all aspects of silica loss before burial, such as dissolution in the eutrophic zone or within the sediments, it is possible to reconstruct the production rate of radiolarian in the surface water, which would be used to estimate the paleo-primary productivity. This method is applied to the end Permian chert sequence from Dalong Formation in Dongpan area, southwestern China. The resulting paleo-primary productivity of the ocean in end Permian south China is about 477.9 g C/m2/a during the sedimentation of cherts, which, to some extent, agrees with the primary productivity reported for some modern oceans.

South Korea’s increasing status in regional and global affairs has started to draw substantial attention. This study focuses on the China-Japan-Korea triangle and argues that Korea’s exercise of middle power diplomacy is vital to robust trilateralism. Since the late 1990s, Korea has proactively mobilized its diplomatic resources to enhance the institutionalization of China-Japan-Korea trilateralism. Its diplomatic activism fits into the existing theoretical assumptions that middle powers are likely to act as cooperation facilitators and bridge builders. To be specific, Korea’s middle-power diplomacy within the triangle works in two ways: making intellectual contributions and bridging between China and Japan. First, Korea has acted as the main idea proposer, agendasetter and vision designer throughout the evolution of trilateralism, including the first trilateral breakfast summit in 1999, the first independent Trilateral Summit in 2008, and the establishment of the Trilateral Cooperation Secretariat (TCS) in 2011. Second, Korea’s presence in the triangle has provided bridging between China and Japan. Korea’s chairmanship and diplomatic efforts toward resuming the Sixth Trilateral Summit in November 2015 have created a new diplomatic pattern in Northeast Asia whereby cooperative trilateralism incorporates bilateral disputes into a minilateral setting. However, Korea is, after all, a middle power in this triangle with no intention to challenge China or Japan. For this reason, Korea has exerted its middle-power bridging cautiously through a “wait-and-see” approach.