| Primary producer in surface ocean is a key factors to connect the atmosphere system and the ocean system. The researches of primary productivity can help us to know more about climate change in atmosphere, the conditions of ocean water and the carbon transition from atmosphere system to ocean system. Permian-Triassic extinction is the most severely ones in history of earth. Many sections, especially shallow-water section, have been worked around the world. But, researches were focus more on big fossils, less on primary producers, especially in deep-water faces. The researches on primary productivity may play an important role in understanding the evolution of the whole ecosystem during the Permian-Triassic transition.Many Permian-Triassic boundary sections, both shallow-water and deep-water, have been well preserved in South China. Lots of shallow-water sections have been studied carefully; many deep-water sections in South China are still underestimated. Recently, many works show South China is a unique area from other areas across the Permian-Triassic boundary:First, the primary productivitys are decrease in shallow-water sections of South China, different from other areas (primary productivity are increase) from late Permian to early Triassic. Besides, many volcanic ashfall beds are exhibited well in deep-water sections in South China, this is also rare in other sections around the world. Focuses on South China, especially deep-water sections are significant to understand the Permian-Triassic boundary extinction.We learn more from the detailed research of geochemistry and paleontology from two deep-water sections (Dongpan section and Xinmin section):Firstly, primary productivity in deep-water sections is decreasing gradually and more severely closer to the Permian-Triassic boundary. Inputting of lots of volcanic materials into ocean are always accompany with the decrease of primary productivity. This trend is like the shallow-water in South China but opposite to other sections around the world.Secondly, Redox condition is a key factor to the geochemistry indexes of productivity; we integrate different redox proxies (U, V, Mo, Ce anomalies) to indicate the redox condition of Dongpan and Xinmin setions:in Dongpan section, the absence of U, V, Mo and the value of Ce anomalies are less than 1 show the suboxic condition in Dongpan section. We assume the late Permian in Xinmin section anoxic condition by the enrichment of U and V. The values of Ce anomalies are around 1 also indicate the anoxic water, what's more, enrichment of Mo in some bed may indicate euxinic condition. Abundant of terrigenous materials were inputted into ealiest Triassic ocean in Xinmin section, dilute the signal of redox proxies, we cannot distinguish the redox condition carefully.Thirdly, many productivity proxies are influenced large by redox condition in water column. The redox condition is a precondition to the choies of productivity proxies. Dongpan section is suboxic; we choose bio-Ba to indicate the change of productivity. Bio-Ba is low (average 266ppm) and decrease gradually from late Permian to early Triassic. We choose Cu and Zn as productivity proxies as the anoxic conditions in Xinmin section, bio-Cu and bio-Zn have high relativity (R2=0.64), Besides, TOC and bio-Cu also have high relative coefficient (R2=0.5). The high relative coefficient between different productivity proxies indicates the veracity of the productivity indicators. What's more, we calculate the primary productivity quantificational by using geochemistry proxy's models which are available in modern ocean (Ba in Dongpan section, Cu and Zn in Xinmin section). Although the quantitative result can not compare to modern ocean as the uncertain of the liner sedimentary rate, the trend of the calculate values are similar to the other conventional productivity proxies.Fourthly, the first try to indicate paleo-productivity using radiolarian have been carried out, radiolarian and spicules are the main form of bio-silica, at the same time, the number of radiolarian is larger than spicules. The abundance of radiolarian and bio-silica, bio-Ba have high relative coefficient (R2=0.65 and 0.32 respectively), especially, the abundance of Spumellaria and bio-silica, bio-Ba have higher relativity (R2=0.72 and 0.48 respectively). The high relative coefficient between bio-silica (radiolarian) and bio-Ba indicate the available of both radiolarian and bio-Ba as paleo-productivity proxies.Finally, the outlets of numerous volcanic ashfall beds in deep-water section indicate abundance volcanic events in South China. The regional volcanic events may play an important role to South China during the Permian-Triassic boundary. Volcanic may induce the redox condition from deep-water to shallow-water (extinction of deep-water species earlier than shallow-water species of radiolarian), Strengthen chemistry weathering of land (CIA and the change of clay mineral); also enlarge terrigenous input to ocean (MS, REE, spore and pollen). Numerous volcanic outputs may the cause of the decrease of primary productivity in South China, different to other areas.
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