Solar insolation driven periodicities in southwest monsoon and its impact on NE Arabian Sea paleoceanography  

作　　者：Syed Azharuddin Pawan Govil Arun Deo Singh Ravi Mishra Mayank Shekhar 

机构地区：[1]Birbal Sahni Institute of Palaeosciences,Lucknow,U.P.,226007,India [2]Department of Geology,Banaras Hindu University,Varanasi,221005,India [3]National Centre for Antarctic and Ocean Research,Vasco-da-Gama,Goa,403804,India

出　　处：《Geoscience Frontiers》2019年第6期2251-2263,共13页地学前缘（英文版）

基　　金：SERB-DST Project No.SR/FTP/ES-53/2013;Council of Scientific and Industrial Research(CSIR)(Grant No.09/528/0022/2018/EMR-1)for the financial assistance in the form of fellowships;supported by fast-track grant of SERB-DST under project No.SR/FTP/ES-53/2013

摘　　要：In the northeastern(NE) Arabian Sea,the fluctuation in terrestrial and freshwater runoff directly depends on southwest monsoon(SWM) precipitation as well as the meltwater flux provided by Indus River.Therefore,analysis of multi-proxy spectral signatures was carried out to trace the high-resolution SWM periodicities and their influence on the productivity,regional sea level fluctuations and depositional processes in the NE Arabian Sea.The time series data of stable isotopes of oxygen(δ^18 O(G.ruber)).carbon(δ^13 C(G.ruber) and δ^13 C(org)) and nitrogen(δ^15 N).Total Organic Carbon(TOC),planktic-benthic foraminiferal ratio(P/B ratio) and>63 μm coarse fraction(CF) were used from two coastal sedimentary cores located offshore Saurashtra,NE Arabian Sea(Core SK-240/485 having 88 m water depth;Core GC/SK-240/496 having 174 m water depth).The REDFIT based spectral analysis recorded significant periodicities(>90% significance) in δ^18 0 time series centered at^1609,~667,~525,~296,~290 and^256 years.Further,the significant periodicities recorded in carbon isotopes time series(δ^13 C(G.ruber) and δ^13 C(org))centered at^681,~512,~471,~452,~438,~360,~292,~275,~269,~245 and^209 years.The significant periodicities in TOC include^471 and-322 years whereas δ^15 N time series recorded significant periodicity centered at-360 years.The significant periodicities in P/B ratio time series centered at^512,~388,~304,~250,~235,~217,~152,~139 and^135 years while CF recorded^268,~216,~209,~198,~188,~173 and^140 years significant periodicities.The observed periodicities in the multi-proxy record consist of similar cycles(within the radiocarbon dating error) which also natch with previously reported solar insolation influenced SWM and other global and regional cycles.Further,the stationarity of the data has been verified using wavelet analysis and shows similar periodicities as observed in REDFIT analysis.Thereafter,the depositional behaviour was studied using correlation analysis of the common periods of δ^18 0 time series of bothIn the northeastern（NE） Arabian Sea,the fluctuation in terrestrial and freshwater runoff directly depends on southwest monsoon（SWM） precipitation as well as the meltwater flux provided by Indus River.Therefore,analysis of multi-proxy spectral signatures was carried out to trace the high-resolution SWM periodicities and their influence on the productivity,regional sea level fluctuations and depositional processes in the NE Arabian Sea.The time series data of stable isotopes of oxygen(δ18OG.ruber).carbon(δ13CG.ruber and δ13Corg) and nitrogen(δ15N).Total Organic Carbon（TOC）,planktic-benthic foraminiferal ratio（P/B ratio） and>63 μm coarse fraction（CF） were used from two coastal sedimentary cores located offshore Saurashtra,NE Arabian Sea（Core SK-240/485 having 88 m water depth;Core GC/SK-240/496 having 174 m water depth）.The REDFIT based spectral analysis recorded significant periodicities（>90% significance） in δ180 time series centered at1609,667,525,296,290 and256 years.Further,the significant periodicities recorded in carbon isotopes time series(δ13CG.ruber and δ13Corg)centered at681,512,471,452,438,360,292,275,269,245 and209 years.The significant periodicities in TOC include471 and-322 years whereas δ15N time series recorded significant periodicity centered at-360 years.The significant periodicities in P/B ratio time series centered at512,388,304,250,235,217,152,139 and135 years while CF recorded268,216,209,198,188,173 and140 years significant periodicities.The observed periodicities in the multi-proxy record consist of similar cycles（within the radiocarbon dating error） which also natch with previously reported solar insolation influenced SWM and other global and regional cycles.Further,the stationarity of the data has been verified using wavelet analysis and shows similar periodicities as observed in REDFIT analysis.Thereafter,the depositional behaviour was studied using correlation analysis of the common periods of δ180 time series of both the cores.The result suggests

关 键 词：SOUTHWEST MONSOON PERIODICITIES Arabian SEA Spectral analysis FORAMINIFERA 

分 类 号：X70[环境科学与工程—环境工程]