Sediment Characteristics And Provenance Analysis Of The East Siberian Arctic Shelf

The East Siberian Arctic shelf is the world's broadest continental shelf,with distinctive sedimentary system,complex ocean circulation and massive terrestrial material and freshwater inputs.To study the distribution characteristics,sources and transport processes of modern sediments will contribute to a better understanding of the source-sink processes of Arctic shelf sediments and reveal the mechanism of interaction between the Arctic marginal sea and surrounding continents and oceans.In previous studies,the research on source-sink mainly focus on the description of sedimentary characteristics,and is lack of systematic research in view of source-sink process.Besides,most of the research uses a single indicator for source tracing,the combination of multi-indicators is relatively less.In this paper,the grain size,major and trace elements,clay minerals,bulk minerals and Sr-Nd-Pb isotopes of the surface sediments in the East Siberian Arctic shelf were analyzed,and the distribution characteristics of each indicator were described.Based on cluster analysis the study area were divided into different provinces,and the source and transport of the sediments were discussed.The results show that the study area can be divided into four provinces: the nearshore and estuary zone of the East Siberian Sea(province I),central of the East Siberia Sea(province ?),the northern deep water area of the East Siberian Sea(province III)and the Chukchi Sea(province IV).The sediments in province I are mainly composed of silt and sandy silt,with an average grain size of 5.80 ?.The grain size are the coarsest in the study area;Si O2,Ti O2,Zr,Sr have the highest content in this area,and all other elements are at low values;?REE has the highest content in this area,with 178 ?g/g.There is distinct differentiation between light and heavy rare earth element and no obviously Ce anomaly while Eu negative anomaly is the most remarkable in the four provinces;the average of 87Sr/86 Sr ratio is 0.71376,?Nd is-9.62.207Pb/206 Pb ratio is the highest of the four provinces,with an average of 0.83415;Illite is the dominant which accounts for 70% of the whole clay minerals.And the second is chlorite,with an average content of 19%,and the contents of smectite and kaolinite are less than 10%;Bulk minerals are dominated by plagioclase,quartz and K-feldspar.feldspar /quartz(F/Q)ratio is 1.78,which is the highest of the four sedimentary regions.The sediments in this area are mainly rivers(Indigirka and Kolyma rivers)and coastal erosion input materials.The sediments in province II are mainly composed of silt and mud,with an average grain size of 6.91 ?;Elements such as Mn O,Ni,Ba,etc.show high content in this area;?REE is 166 ?g/g,which is the lowest in the East Siberian Sea.The differentiation of the light and heavy rare earth element is obvious,Ce basically no anomalies,Eu is negative anormaly;87Sr/86 Sr ratio is 0.71401 which is slightly higher than that in province I,?Nd is-9.16,207Pb/206 Pb ratio slightly lower than province I,with an of average 0.83002;Clay minerals are very similar to province I;Bulk minerals are dominated by quartz,plagioclase and mica,and the F/Q ratio is 1.29.The sediments in this area are mainly fine-grained derived by rivers,which are also influenced by sea ice process.As the distance increasing offshore,the content of marine authigenic components begin to increase.The sediments in province III are mainly mud,with an average grain size of 7.47 ?,which is the finest sediments in the study area;Elements content of Al2O3,TFe2 O,Mg O,V,Li and Cr reach maximum;the ratio of ?LREE/?HREE is 9.08,which is the most distinct area of light and heavy rare earth element differentiation.Ce basically no anomalies,Eu is negative anormaly;87Sr/86 Sr ratio is 0.71802,which is the highest of the four province,the average of ?Nd is-10.30,which is the minimum of the four province,and the average 207Pb/206 Pb ratio is 0.82760;The illite content is the lowest in this area,with an average of 60%,and the content of smectite and kaolinite reaches its maximum,with 12% and 13%,respectively;Bulk minerals are dominated by quartz,plagioclase and mica,and the average content of calcite and dolomite is the highest in this area.the F/Q ratio is 1.24.In addition to the material imported from the East Siberian shelf,the sediments in this area are likely to be influenced by the material carried by the Atlantic waters and the Beaufort Gyre.The sediments in province ? are mainly composed of silt and sandy silt,with an average grain size of 6.41?;Elements are characterized by higher contents of Na2 O,P2O5,Ca O and Sr;The content of ?REE is 130 ?g/g,which is the minimum of the four provinces,and the ?LREE/?HREE ratio is 7.72,differentiation of light and heavy rare earth element are the weakest;?Ce anomalies,Eu is negative abnormal;The average of the ?Nd is-8.06,which is the maximum in the four province.The 87Sr/86 Sr ratio is 0.71099,and 207Pb/206 Pb ratio is 0.81318,which are the lowest in the four provinces.The illite content is slightly lower than the East Siberian sea,and the chlorite is the most abundant in this region,with an average content of 25%;Bulk minerals are dominated by quartz,plagioclase and mica,and the average content of chlorite and mica is the highest in this area.the F/Q ratio is 1.24.The sediment sources in this area include terrigenous and biogenic materials,and coastal erosion is the main source of terrigenous materials.Affected by the Pacific inflow water,this area is the region with the highest biological productivity in the study area.