| Kaifeng city closely associated with the rise and fall of the Yellow River, the Yellow River floodmultiple dynasties of the ancient city of Kaifeng silt buried in the ground, forming a unique " city abovecities " spectacle. However, the exact documented the ancient city of Kaifeng Yellow River flood eventdestroyed only three times, the number of other events of the Yellow River Flood, time of occurrence, thereis no scientific certainty the extent of the floods. Application methods stratigraphy of sedimentary cyclestudies should be carried out effective way to solve these problems. However, the ancient city of KaifengYellow River alluvial deposition differs from underground loess deposition and lake sedimentary sea, afterevery flood, due to the impact of human disturbance and post-disaster urban reconstruction activitiesTaobao normal sedimentary sequence is often disrupted, to particle size analysis to identify sedimentaryrhythm brought a lot of difficult, so it’s difficult to rely solely on traditional particle size analysis todetermine the sedimentary cycle, we need to find other proxies to determine its consolidated sedimentarycycles.Select this article Kaifeng City as the research object, based on field surveys, sampling, laboratoryanalysis on the western suburbs of Kaifeng City of Henan University (ZKjm), Old Town of HenanUniversity (ZKsz) Typical core (depth of25m) cylindrical core samples for high-density sample (samplespacing of10cm), so a total of438samples were obtained. Carring out in the laboratory sample sizeanalysis, color identification, organic carbon and carbon black content determination, suburban ZKszstratigraphic core cycle granularity and black carbon cycle as a reference for the city by human activitiessedimentary cycles for a more systematic division research, draw the following conclusions: （1）Suburban ZKjmcore clay and sand strata in accordance with the content from the bottom ofdivision nine cycles respectively. they are the first sedimentary cycle (23.8m or less), the secondsedimentary cycle (20.3~23.8m), the third sedimentary cycle (14.5~20.3m), the fourth sedimentary cycle(12~14.5m), the fifth sedimentary cycle (7.8~12m), the sixth sedimentary cycle (5.8~7.8m), the seventhsedimentary cycle (2.5~5.8m), the eighth sedimentary cycle (1.8~2.5m), the ninth sedimentary cycle (0.8~1.8m) respectively.Town ZKszformation of surface core to within6.5m depth range, due to the impact of humandisturbance, granularity cycles unclear; Underground6.5~25m from the bottom can be roughly dividedinto five sedimentary cycles. they are the first sedimentary cycle (21.5~25m), the second sedimentarycycle (19.5~21.5m), the third sedimentary cycle (15.5~19.5m), the fourth sedimentary cycle (11~15.5m),the fifth sedimentary cycle (6.5~11m) respectively. Two cores6.5m below the grain size and boundariesare basically the same number of cycles in the surface. Underground11~13m may be the original stratumof the Warring States period.(2) According to the content of carbon black,we can learn that the next suburb ZKjmcore formationscan be divided into eight cycles, and its boundaries are consistent granularity cycles, respectively, they arethe first sedimentary cycle (18.8~24.5m), the second sedimentary cycle (14.5~18.8m), the thirdsedimentary cycle (13~14.5m), the fourth sedimentary cycle (7.8~13m), the fifth sedimentary cycle (5.3~7.8m), the sixth sedimentary cycle (2.5~5.3m), the seventh sedimentary cycle (1.8~2.5m), the eighthsedimentary cycle (0.8~1.8m) respectively. Therefore, the carbon black content in alluvial strata dividedthe Yellow River flood cycles, you can compensate for the lack of traditional proxies of particle size due toanthropogenic disturbance. Can be used as an alluvial deposits of sedimentary cycles proxies division.(3) In accordance with the black carbon content can be from the bottom up urban ZKszformation, we divided into nine cycles, they are the first sedimentary cycle (20.8~25m), the second sedimentary cycle(17.8~20.8m), the third sedimentary cycle (13.6~17.8m), the fourth sedimentary cycle (11.7~13.6m), thefifth sedimentary cycle (7.2~11.7m), the sixth sedimentary cycle (3.2~7.2m), the seventh sedimentarycycle (2.2~3.2m), the eighth sedimentary cycle (1.3~2.2m), the ninth sedimentary cycle (0.5~1.3m)respectively. From6.5~25m below the surfacethe of black carbon deposition cycle is consistent with theparticle size deposition cycle.(4) There is good correlation between the urban black carbon content and organic carbon content inthe suburbs. Pearson correlation coefficient of carbon black in the western suburbs of Kaifeng ZKjmcorestratigraphic stratum for each sample and organic carbon content between0.52, there was a significantpositive correlation (p <0.01), in Kaifeng city ZKszborehole core stratigraphic stratum for each samplePearson correlation coefficient of black carbon and organic carbon content is between0.68and there was asignificant positive correlation (p <0.01). From the result we can know, some intrinsic link between blackcarbon and organic carbon, either carbon black from biomass burning, or part of the organic carbon fromthe carbon black. In addition, the different natural conditions and human activities may lead to theformation urban black carbon and organic carbon content.(5) ZKjmcore in the western suburbs of the BC/OC value changing with depth range is larger, urbanZKszcore formation is greater than the western suburbs of BC/OC average ZKjmcore. Kaifeng suburbsZKjmcore strata segment0~12m (cultural layer) on average BC, OC and the BC/OC were0.33g/kg,2.37g/kg and0.15, on the well, ZKjmcore formation under the average period of12~25m BC, OC and theBC/OC were0.34g/kg,1.43g/kg and0.28, Urban ZKszcore strata segment0~13m (cultural layer) onaverage BC, OC and the BC/OC were0.99g/kg,3.49g/kg and0.25, ZKszcore strata under stratum13~25m average BC, OC and the BC/OC were0.40g/kg,1.61g/kg and0.26, It is shown that suburbs on core stratum of the formation of black carbon is mainly derived from biomass burning; And city formation ofblack carbon is the outcome of combined action of burning biomass and minerals, And two core period ofBC/OC high value couldn’t indicate that black carbon was the result of the combination of biomass andmineral fuel combustion, which the formation organic carbon content is low, the source of black carbon isstill the biomass burning. |
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