| The process research of source-sink system is currently one of the hot research topic,involves the material source and the ownership of the sediment,which includes the source area of the earth’s crust movement,weathering erosion and climate change information,such as rivers,ice and wind carrying information,as well as the convergence zone of wave,tidal current,sediment diffusion and Marine sedimentary system construction information.Backed by China’s largest and highest the edge of the mainland,facing the vast sea,with about 18000 kilometers of coastline,the eastern continental margin since late quaternary,accepted world-class rivers(the Yangtze river,Yellow River and the pearl river)and the island mountain river river(e.g.,Taiwan province)the huge amount of sediment into the sea,to become the world’s material exchange,one of the most active continental margin,therefore has become the study of sedimentary environment and source process ideal region.In this study,five boreholes YZ02,YZ10,YZ05,YZ06 and YZ07,which are distributed in the west,central and south of the South Yellow Sea,are taken as the research object.The evolution of sedimentary environment and the source and change of sediment material in the South Yellow Sea since the late quaternary are mainly studied.Specific technical route is as follows: first of all to systemic summarized predecessors’ achievements,establish the south yellow sea to the late quaternary borehole s framework and sedimentary sequence,the second key by detrital zircon U-Pb dating research drilling different horizon of detrital zircon age components distribution,not only the traditional age spectrum visual contrast analysis comparison,also through the quantitative analysis method to carry on comparative analysis to the data,reduce the subjective judgment on visual discriminant error as much as possible.Quantitative analysis of detrital zircon data is rarely used in domestic studies.This paper adopts age visual comparison analysis and three kinds of quantitative analysis methods to comprehensively analyze the data.The three types of quantitative analysis methods are quantitative comparison method based on age spectrum(Likeness and Similarity coefficient),quantitative analysis method based on non-parametric test(K-S Test),and Multi-dimensional Scaling(MDS)which can visualize the quantitative analysis method again.By comparing the age maps of zircons from the lower reaches of the Yangtze river and the lower reaches of the Yellow River,it was found that the age maps of the lower reaches of the Yangtze river and the Yellow River were quite different,which made it possible to judge the source regions of the Yangtze river and the Yellow River.Zircons in the lower reaches of the Yangtze river are mainly concentrated in the six age components of 0-150 ma,150-300 ma,700-900 Ma,1800-2000 Ma,and 2400-2700 Ma,with 150-250 Ma as the main peak,200 Ma as the main peak,700-900 Ma as the secondary peak,and 750 Ma as the secondary peak.The ages of zircons in the lower reaches of the Yellow River are mainly concentrated in the four age components of 200-350 Ma,350-500 Ma,1700-2000 Ma and 2400-2600 Ma,of which 350-500 Ma is the main peak,400 Ma the main peak,200-350 Ma the secondary peak and 290 Ma the secondary peak.1700-2000 Ma and 2400-2600 Ma are age components common to the Yellow River in the Yangtze river,which cannot be used as a standard to distinguish the provenance of the Yangtze river and the Yellow River.Zircons of 150-350 ma exist in both the Yangtze river and the Yellow River.However,zircons of this component from the Yangtze river are mainly concentrated around the peak value of 200 Ma,while those from the Yellow River are mainly concentrated around 290 Ma.Therefore,in the 150-350 ma component,the peak values of 200 Ma and 290 Ma can be used as a basis to distinguish the Yangtze river and the Yellow River.The content of 350-450 ma in the lower reaches of the Yangtze river is small,but it occupies a dominant position in the lower reaches of the Yellow River.Therefore,350-450 ma can be used as the characteristic peak of the Yellow River,and the content of 700-900 Ma in the lower reaches of the Yellow River is small,but the content of 700-900 Ma in the lower reaches of the Yangtze river is relatively large.Therefore,700-900 ma can be used as the characteristic age component of the Yangtze river.In addition,the Yangtze river contains a small amount of Cenozoic zircons less than 100 Ma from the lower Yangtze plate,while the Yellow River does not,which can be used as the signature peak of the source of the Yangtze river.According to the four analysis methods,the age ranges of detrastic zircons in holes YZ02,YZ05,YZ06,YZ07 and YZ10 are mainly from 0-100 Ma,100-300 Ma,300-500 Ma,700-900 Ma,1600-2000 Ma and 2400-2700 Ma,with 100-300 Ma as the main peak and 200 Ma as the main peak.700-900 Ma is the secondary peak,and 750 Ma is the secondary peak.According to the quantitative analysis of the Yangtze river and Yellow River source ratio and orientation,the material sources of the south yellow sea can be divided into the mixture of source of the Yangtze river,the Yangtze river as the main source,the source of Yellow River,the Yellow River source and mix source,including the Yangtze river and Yellow River the story to point to by the Yangtze river or the Yellow River,single source of supply material sample determination standard for the four types of contrast methods were consistent to the Yangtze river or the Yellow River,and represents the characteristics of the age of the Yangtze river or the Yellow River component proportion and downstream of the river and the Yangtze river or the components of broadly;Yangtze river dominated mixed source refers to the source material of samples provided by the Yangtze river,Yellow River material blending,but not dominant,discriminant standard method for the analysis of four types of at least two methods results point to the Yangtze river,and on behalf of the Yangtze river in the sample characteristics of the age of component proportion(< 100 ma and 700-900 ma)similar to or greater than the Yangtze river downstream of the components and characteristics of the Yellow River age components(350-450 ma)ratio is greater than the Yangtze river downstream components this age.;Yellow River dominated mixed source refers to sample the source material is given priority to with material of the Yellow River,the Yangtze river have mixed but not dominant,discriminant standard method for the analysis of four types of at least two kinds of methods to analyze the results point to the Yellow River,on behalf of the Yellow River features age components in the sample(350-450 ma)share similar to or greater than the lower reaches of the Yellow River this age components,also on behalf of the Yangtze river characteristics of components(< 100 ma and 700-900 ma)of greater than this component on the lower reaches of the Yellow River;The Yangtze river,Yellow River of the Yangtze and yellow rivers in the mixed source refers to the sample signal is very strong,has important influence on the samples are two river,discriminant standard method for the analysis of four types of conflicting results,such as in K-S test results are shown in the case of p value is much lower than 0.05 and the components in the statistical characteristics of the age accounted for and the Yangtze river or the Yellow River downstream proportion are inconsistent.The five boreholes were comprehensively judged according to the above principles,and it was found that the main sources of the Yangtze river and the main mixed sources of the Yangtze river were the sources of the MIS6 to MIS5 stages.In MIS3 stage,the influence of the Yellow River increased significantly,and the mixed source dominated by the Yellow River and the mixed source dominated by the Yangtze river.The MIS2 stage is dominated by the mixed sources of the Yangtze river and the Yellow River and the mixed sources dominated by the Yangtze river.In the MIS1 stage,the mixed source of the Yangtze river and the Yellow River,the mixed source of the Yangtze river and the source of the Yangtze river were the main sources.The results show that since the late quaternary period,the sediments in the study area were transported mainly by the Yangtze river and mixed with substances from the Yellow River in some stages.Mainly after MIS3 stage,the influence of the Yellow River gradually increased and became the main source contribution area in the research area together with the Yangtze river.However,the source of the Yellow River was mainly concentrated in the borehole in the northern sea area.From the perspective of spatial distribution,the farther south the Yellow River is,the less influence it has on the study area.The results further indicate that since the late quaternary of the southern yellow sea,the Yangtze river enters the sea in the northern jiangsu plain for most of the time,and is the main and stable source of the continental shelf sediments in the southern yellow sea.The influence of the Yellow River on the south yellow sea is discontinuous due to the water amount in different periods and the south-north oscillation of the estuary.The ancient Yellow River flow path may deviate from the research area for most of the time without direct material supply,but only has a direct impact on hole YZ02 in the MIS3 stage.The four types of detrital zircon of advantages and disadvantages for the methods of data analysis,the traditional visual contrast analysis to intuitive judgment distribution and the contribution of each age sample components,but this method is not applicable to large amount of data,will be missing key information and maps for age more similar as sample "decision is not clear" existence ".Quantitative comparison method can fast and efficient for interpretation,in the face of highly similar source area compare to the sample,you can quickly determine the source area,and not only make up for the visual contrast the result of the decision is not clear,can also be a mixture of visual judgement source results further refinement,tracer to achieve more accurate source requirements.But this kind of method for source area of complex samples,such as different space in this study due to the different period,in the study area of the Yangtze river and Yellow River source input proportion is different,will inevitably cause the sample after mixed age composition distribution and the Yangtze river Yellow River were similar or not similar to two kinds of situations,makes quantitative analysis result has a certain error,in the K-S inspection of p < 0.05,not through the test;The MDS diagram shows that the sample points are far away from the Yangtze river and the Yellow River.In addition,the quantitative analysis method of age spectrum difference is mainly calculated based on the results of probability density map(PDP)or kernel density curve(KDE),which requires data preprocessing.Therefore,the reliability of this method is controversial.The difference test method of non-parametric hypothesis does not need to preprocess the data,but the credibility of the test effect depends on the amount of data in the sample.The larger the amount of data is,the more reliable the test result will be.Multi-dimensional scaling method(MDS)simplifies the variables of multiple age components to two-dimensional or three-dimensional space,resulting in distribution distortion.Therefore,this study suggests that the source tracer method for detrastic zircons should be comprehensively analyzed by a variety of methods,and the actual geological background of the study area should be considered.Finally this paper discusses the four types of detrital zircon of advantages and disadvantages for the methods of data analysis,the traditional visual contrast analysis to intuitive judgment distribution and the contribution of each age sample components,but this method is not applicable to a large quantity of data,without missing key information,but also for age atlas similarity degree higher samples exist "decision is not clear".And quantitative comparison method can fast and efficient for interpretation,in the face of highly similar source area compare to the sample,you can quickly determine the source area,and not only make up for the visual contrast the result of the decision is not clear,can also be a mixture of visual judgement source results further refinement,tracer to achieve more accurate source requirements.But this kind of method for source area of complex samples,such as different space in this study due to the different period,in the study area of the Yangtze river and Yellow River source input proportion is different,will inevitably cause the sample after mixed age composition distribution and the Yangtze river Yellow River were similar or not similar to two kinds of situations,makes quantitative analysis result has a certain error,in the K-S inspection of p < 0.05,not through the test;The MDS diagram shows that the sample points are far away from the Yangtze river and the Yellow River.In addition,the quantitative analysis method of age spectrum difference is mainly calculated based on the results of probability density plot(PDP)or kernel density plot(KDE),which requires data preprocessing.Therefore,the reliability of this method is controversial.The difference test method of non-parametric hypothesis does not need to preprocess the data,but the credibility of the test effect depends on the amount of data in the sample.The larger the amount of data is,the more reliable the test result will be.Multi-dimensional scaling method(MDS)simplifies the variables of multiple age components to two-dimensional or three-dimensional space,resulting in distribution distortion.Therefore,this study suggests that the source tracer method for detrastic zircons should be comprehensively analyzed by a variety of methods,and the actual geological background of the study area should be considered. |
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