중기 플라이스토세 전이기 전후 북태평양 중앙 해역 퇴적물에 기록된 풍성 퇴적물 입자 퇴적 양상 변화 복원
Reconstruction of Changes in Eolian Particle Deposition Across the Mid-Pleistocene Transition in the Central Part of the North Pacific
2
조회
0
다운로드
1
인용
0
참고문헌
키워드
초록
We investigated flux, grain size distribution, Nd-Sr isotope composition, mineral composition, and trace metal composition (REEs and Sc) of inorganic silicate fraction (ISF, mainly Asian dust with an unrestricted amount of volcanic materials) deposited during 600~1000 ka across the Mid-Pleistocene Transition at core NPGP 1401-2A (32°01'N, 178°59'E, 5205m) taken from the central part of the North Pacific. Our results reveal about a 2-fold increase in ISF flux after 800 ka, which is associated with an increase in La/Sc and a decrease in mean grain size. Asian dusts are finer than volcanic materials and La/Sc increases with the enhanced contribution of Asian dusts. Thus, increased flux after 800 ka can be explained by the increased contribution of Asian dusts relative to volcanic materials, likely due to an intensified Westerly Jet (WJ) and the drying of the Asian continent after the MPT. Mean grain size of ISF varies systematically in relation to glacial-interglacial cycles with a decrease during glacial stages, which is consistent with the previous results in the study area. Such a cyclical pattern is also attributed to the increase in the relative contribution of Asian dusts over volcanic components in glacial stages due to intensified WJ and drying of the Asian continent. Thus, it can be concluded that climate changes that had occurred across the MPT were similar to those of interglacial to glacial transitions at least in terms of the dust budget. Different from the Shatsky Rise, however, compositional changes associated with glacial-interglacial mean grain size fluctuations are not observed in Nd-Sr isotope ratios and trace element composition in our study of the Hess Rise. This may be attributed to the location of the study site far (> 4,000 km) from the volcanic sources. The volcanic component at the study site comprises less than 10% and varies within 3% over glacial-interglacial cycles. Such a small variation was not enough to imprint geochemical signals.
Abstract
We investigated flux, grain size distribution, Nd-Sr isotope composition, mineral composition, and trace metal composition (REEs and Sc) of inorganic silicate fraction (ISF, mainly Asian dust with an unrestricted amount of volcanic materials) deposited during 600~1000 ka across the Mid-Pleistocene Transition at core NPGP 1401-2A (32°01'N, 178°59'E, 5205m) taken from the central part of the North Pacific. Our results reveal about a 2-fold increase in ISF flux after 800 ka, which is associated with an increase in La/Sc and a decrease in mean grain size. Asian dusts are finer than volcanic materials and La/Sc increases with the enhanced contribution of Asian dusts. Thus, increased flux after 800 ka can be explained by the increased contribution of Asian dusts relative to volcanic materials, likely due to an intensified Westerly Jet (WJ) and the drying of the Asian continent after the MPT. Mean grain size of ISF varies systematically in relation to glacial-interglacial cycles with a decrease during glacial stages, which is consistent with the previous results in the study area. Such a cyclical pattern is also attributed to the increase in the relative contribution of Asian dusts over volcanic components in glacial stages due to intensified WJ and drying of the Asian continent. Thus, it can be concluded that climate changes that had occurred across the MPT were similar to those of interglacial to glacial transitions at least in terms of the dust budget. Different from the Shatsky Rise, however, compositional changes associated with glacial-interglacial mean grain size fluctuations are not observed in Nd-Sr isotope ratios and trace element composition in our study of the Hess Rise. This may be attributed to the location of the study site far (> 4,000 km) from the volcanic sources. The volcanic component at the study site comprises less than 10% and varies within 3% over glacial-interglacial cycles. Such a small variation was not enough to imprint geochemical signals.
참고문헌 (34)
- Biscaye PE, "Asian provenance of glacial dust (stage 2) in the Greenland Ice Sheet Project 2 ice core, Summit, Greenland", J Geophys Res Oceans, 102(C12), pp.26765~26781 (1997)
- Chen J, "Nd and Sr isotopic characteristics of Chinese deserts: Implications for the provenances of Asian dust", Geochim Cosmochim Ac, 71(15), pp.3904~3914 (2007)
- Chen Z, "Evolving sources of eolian detritus on the Chinese Loess Plateau since early Miocene: Tectonic and climatic controls", Earth Planet Sc Lett, 371, pp.220~225 (2013)
- Chuey JM, "Late Pleistocene paleoclimatology of the central equatorial Pacific: A quantitative record of eolian and carbonate deposition", Quaternary Res, 28(3), pp.323~339 (1987)
- Clark PU, "The middle Pleistocene transition: Characteristics, mechanisms, and implications for long-term changes in atmospheric pCO2", Quaternary Sci Rev, 25(23−24), pp.3150~3184 (2006)
- Clemens SC, "One million year record of summer monsoon winds and continental aridity from the Owen Ridge (Site 722), northwest Arabian Sea", Proceedings of the ocean drilling program, Scientific results, 117, pp.365~388 (1991)
- deMenocal PB, "Influences of high- and low-latitude processes on African terrestrial climate: Pleistocene eolian records from equatorial Atlantic Ocean Drilling Program site 663", Paleoceanography, 8(2), pp.209~242 (1993)
- Hovan SA, "28. Late Cenozoic atmospheric circulation intensity and climatic history recorded by Eolian deposition in the Eastern Equatorial Pacific Ocean, Leg 138", Proceedings of the Ocean Drilling Program, Scientific Results, 138, pp.615~625 (1995)
- Hovan SA, "Late Pleistocene continental climate and oceanic variability recorded in northwest Pacific sediments", Paleoceanography, 6(3), pp.349~370 (1991)
- Folk RL, "Petrology of sedimentary rocks: Austin", pp.182~ (1974), Hemphill
- Imbrie J, "Milankovitch and climate", pp.269~305 (1984), Springer
- Jacobsen SB, "Sm-Nd isotopic evolution of chondrites", Earth Planet Sc Lett, 50(1), pp.139~155 (1980)
- Janecek TR, "Quaternary fluctuations in the northern hemisphere trade winds and westerlies", Quaternary Res, 24(2), pp.150~163 (1985)
- Jiang F, "Contribution of A sian dust and volcanic material to the western Philippine Sea over the last 220kyr as inferred from grain size and Sr-Nd isotopes", J Geophys Res-Oceans, 121(9), pp.6911~6928 (2016)
- L.R. Johnson, "Particle-size fractionation of eolian dusts during transport and sampling", Marine Geology, 21(1), pp.M17~M21 (1976), Elsevier BV[DOI]
- Kanayama S, "Size-dependent geochemical characteristics of Asian dust", J Meteorol Soc Jap, 83, pp.107~120 (2005)
- Lisiecki LE, "A Plio-Pleistocene stack of 57 globally distributed benthic δ18O records", Paleoceanography, 20, pp.1~17 (2005)
- McClymont EL, "Pleistocene sea-surface temperature evolution: Early cooling, delayed glacial intensification, and implications for the mid-Pleistocene climate transition", Earth-Sci Rev, 123, pp.173~193 (2013)
- Nagashima K, "Orbital-and millennial-scale variations in Asian dust transport path to the Japan Sea", Palaeogeogr Palaeocl, 247(1−2), pp.144~161 (2007)
- Nagashima K, "Millennial-scale oscillations of the westerly jet path during the last glacial period", J Asian Earth Sci, 40(6), pp.1214~1220 (2011)
- Nagashima K, "Westerly jet-East Asian summer monsoon connection during the Holocene", Geochem Geophy Geosy, 14(12), pp.5041~5053 (2013)
- Parkin DW, "Trade-winds during the glacial cycles", P Roy Soc A-Math Phy, 337(1608), pp.73~100 (1974)
- Paterson GA, "New methods for unmixing sediment grain size data", Geochem Geophy Geosy, 16(12), pp.4494~4506 (2015)
- Pisias NG, "Late Pleistocene paleoclimatology of the central equatorial Pacific: Sea surface response to the southeast trade winds", Paleoceanography, 3(1), pp.21~37 (1988)
- Raymo ME, "Evolution of Atlantic-Pacific δ13C gradients over the last 2.5 my", Earth Planet Sc Lett, 97(3−4), pp.353~368 (1990)
- Rea DK, "The paleoclimatic record provided by eolian deposition in the deep sea: The geologic history of wind", Rev Geophys, 32(2), pp.159~195 (1994)
- Rea DK, "Late cretaceous history of eolian deposition in the mid-pacific mountains, central North Pacific Ocean", Palaeogeogr Palaeocl, 36(1−2), pp.55~67 (1981)
- Rea DK, "Late Cenozoic changes in atmospheric circulation deduced from North Pacific eolian sediments", Mar Geol, 49(1−2), pp.149~167 (1982)
- Seo I, "Movement of the Intertropical Convergence Zone during the midpleistocene transition and the response of atmospheric and surface ocean circulations in the central equatorial Pacific", Geochem, Geophys, Geosys, 16(11), pp.3973~3981 (2015)
- Seo I, "Sr-Nd isotope composition and clay mineral assemblages in eolian dust from the central Philippine Sea over the last 600 kyr: Implications for the transport mechanism of Asian dust", J Geophys Res-Atmospheres, 119(19), pp.11492~11504 (2014)
- Shackleton NJ, "Investigation of late quaternary paleoceanography and paleoclimatology", pp.449~463 (1976), Geological Society of America
- Shen Z, "Characteristics of clay minerals in Asian dust and their environmental significance", China Part, 3(5), pp.260~264 (2005)
- Shin JY, "Wavelet-based verification of a relative paleointensity record from the North Pacific", Earth Planets Space, 71(1), pp.1~14 (2019)
- Wenfang Zhang, "The application of Neodymium isotope as a chronostratigraphic tool in North Pacific sediments", Geological Magazine, pp.1~9 (2019), Cambridge University Press (CUP)[DOI]