1. Rapid Sediment Transfer from a High- Standing Island to the Deep Sea: Evidence from Clay Mineral Assemblages Daidu Fan, Yangyang Wang Tongji University, Shanghai James T. Liu National Sun Yat-sen University, Gaoxiong ddfan@tongji.edu.cn

2. Long-Term Climate Regulator The orogeny has been widely considered as a climate regulator through consumption of CO 2 by rock weathering or delivering POC by rivers to the ocean Global cooling to form ice sheets Seawater δ 18 O getting heavier Courtesy from website Steep slope Orographic rainfall, monsoon Fresh mineral Willenbring and von Blanckenburg (2010) Nature 465 Decrease in amospheric CO 2 Increase in Marine sedimentation

3. Long-Term Climate Regulator The orogeny has been widely considered as a climate regulator through consumption of CO 2 by rock weathering or delivering POC by rivers to the ocean to be efficiently buried Over the Neogene, the effect of silicate weathering is 2-3 times lower than the increase in the amount of POC in the sedimentary reservoir LETTERS

4. Relationship between chemical weathering and physical erosion Relationship between chemical weathering rate and physical erosion for granitoic watersheds and basaltic basins Gabet and Mudd, 2009, Geology (37) Transport-limited weathering: open circles located along the 1:1 line, stable cratons Kinetic-limited weathering: others depart from the line, commonly in the orogenic zones ? The breakpoint for positive to negative relationships

5. Test Ground: Small Mountainous Rivers (SMR) Milliman and Farnsworth, 2011 Dadson et al. (2003), Science Area (km 2 )Annual Sediment Flux (Mt yr -1 ) Sediment Yield t km -2 yr -1 Changjiang 180  10 4 160-50090-280 Taiwan 3.6  10 4 3809500 Gaoping 0.33  10 4 4915000 New Guinea 78.6  10 4 17002160

6. Taiwan and Gaoping River-Sea System Uplift of Taiwan by oblique collision between the Luzon arc and the Asian continental margin over the past 5 -7Ma Steep gradient Frequent earthquakes Heavy precipitation by typhoons Producing huge mass-wasting and hyperpycnal flows

7. Sampling Locations Short cores from the Gaoping continental margin

8. XRD curve interpretations Relative percentages of clay minerals calculated using the MacDiff software Illite chemistry index: a ratio of 5 Å and 10 Å peak areas Illite crystallinity: IB (integral breadth) or FWHM (full width at half maximum) of the glycolated 10 Å peaks Lower IB/FWHM values represent higher crystallinity, characterizing weak hydrolysis in the provenance area with a dry and cold climate (Chamley, 1989)(Chamley, 1989) < 2 um

9. Results Predominant illite (48-70%, average 58%) and chlorite (30-46%, average 39%) Scare smectite and Kaolinite

10. High consistency of clay-mineral compositions in the Taiwan-river systems Obvious difference from the rivers draining the Asia continent Good tracer for fluvial sediment distribution in SCS

11. Tracing sediment distribution patterns in the Gaoping continental margin Contour-parallel distribution of sediments, with some exotic sediments from the Pear River and Luzon rivers by ocean circulations Resuspension and redistribution reduce terrestrial POC content in the lower slop Illite Chlorite SmectiteKaolinite Mud% TOC% Sedimentation rate C/N

12. Contrasting weathering regimes between small and large high-mountainous rivers Much higher chemical weathering in large high-mountainous rivers than small mountainous rivers Primary minerals: physical weathering products Secondary minerals: chemical weathering products Sediment samples from the lower reach or estuarine section of the rivers

13. Contrasting weathering regimes between small and large high- mountainous rivers Bi et al., 2015 He et al., 2013 Downstream increase in the chemical weathering degree

14. Hyperpynal flows 2004/7/1, pre-typhoon Cs=1 g/l 2004/7/3, in typhoon Cs=65 g/l Courtesy from Gao, 2013 Major features Thin regoliths Bedrock erosion Slope mass-wasting Less developed floodplain Hyperpynal flows Turbidity current

15. Physical erosion vs. chemical weathering Bi et al., 2015 The ratio of W chem (Chemical weathering rate) to W mech (mechanical weathering rate) decreases as the W mech increases Different power laws of W chem and W mech are examined between cratonic (0.66 exponent) and alpine rivers (0.29-0.47 exponent), denoting a tardy response of chemical weathering to high elevated physical erosion rates Kinetic limited weathering

16. Terrestrial TOC flux and burial in the sea Liu et al., 2013, Annual Review of Marine Science Small mountainous rivers have very high sediment yield and flux into the sea, consequently high flux of petrogenetic (fossil) OC Recently reported also high biospheric (non-fossil) OC yield and flux from SMR High fossil OC in the sediments

17. Bao et al. (2015), Scientific Reports 2015 POC export determined by physical erosion Blair and Aller, 2012 Clay minerals serve as a carrier and protector of POC

18. Contribution of Taiwan and Oceanian Islands to the global POC flux Wang and Fan et al., in reviewing Annual terrestrial POC burial flux has been estimated 8-11 TgC yr -1 (~1.5 TgC yr -1 ) from Oceanian islands (Taiwan), accounting for ~16% (2.7%) of the global total, high disproportional to their land percentage of 2.5% (0.024%) in the world’s watershed area.

19. Summary Extreme abundance in primary minerals denote weak weathering regime in the Taiwan rivers Chemical weathering responds tardily to the high elevated physical erosion rates in the active orogens Hyperpycnal flow with high sediment concentrations favors terrestrial TOC transfer and burial in the sea Terrestrial POC burial overwhelms silicate weathering in CO 2 consumption in Taiwan and other Oceanian islands

20. Thanks 谢谢！！！