【作者】 王红霞；

【导师】 林振宏； 蓝先洪；

【作者基本信息】 中国海洋大学 ， 海洋地质， 2008， 博士

【摘要】 本文通过对南黄海两个代表性的钻孔NT1和NT2孔沉积物的矿物和元素地球化学特征的研究,探讨了晚更新世以来南黄海的物质来源和沉积环境。运用数理统计方法将钻孔、长江、黄河及韩国河流沉积物做了对比,确定了不同河流对南黄海物质来源的贡献。论证了南黄海晚更新世以来高海平面时期存在两个“古冷涡”。在南黄海首次发现胶黄铁矿(Fe3S4)、锰方解石和重晶石晶体三种具有环境意义的海洋自生矿物,论述了南黄海冷涡沉积中自生黄铁矿的特征与环境指示意义。NT1孔位于南黄海涡旋泥中心区(123o24.29’N,35o26.60’E),主要沉积了晚更新世以来的细粒物质,孔深70m,鉴定矿物40余种。根据矿物、元素的垂向分布特征及沉积类型,自上而下将NT1孔岩芯分为五层或五个矿物段(十个矿物亚段)。通过将NT1岩芯与长江、黄河、锦江和荣山江沉积物的矿物—地球化学特征进行分析对比可知,在物源方面,第一、三、五层(段)岩芯沉积物的重矿物以自生黄铁矿为主,陆源矿物组合为角闪石、绿帘石、白云石、钛铁矿和片状矿物,显示了与长江的矿物组合更接近,即沉积物可能主要来源于长江;其元素地球化学以富含多数金属氧化物、有机碳和大部分微量元素为特征,对化学元素,富集因子和判别函数分析表明,各种特征均接近于长江,说明沉积物主要来自长江。在环境方面,第一、三、五层由于富集大量的自生黄铁矿,反映了弱的水动力、还原环境以及高海平面时期海相沉积环境;Na/Al、Na/K的比值反映了气候温暖湿润。因此,在高海平面时期和温暖湿润的气候条件下,长江物质对南黄海沉积物的贡献大于黄河、锦江和荣山江。第二、四层(段)的重矿物组合以片状矿物、方解石、绿帘石、角闪石和石榴石为主,显示与黄河矿物组合更接近,沉积物可能主要来自黄河。元素分析反映第二、四层沉积物以富Si、Ca、Na、Mn、P、Sr,贫Al、K、Ti、Mg、Fe、有机碳和贫14种微量元素(除了Sr以外)为特征,对化学元素、富集因子和判别函数分析发现,黄河物质的贡献大于长江、锦江和荣山江。在环境方面,第二、四层的矿物组合与Na/Al、Na/K的比值反映了较强的水动力条件和氧化作用为主的滨岸、河口和陆相沉积环境,反映了低海平面时期和较干燥、寒冷的气候条件。也就是说在低海平面时期和较干燥、寒冷的气候条件下,黄河物质对南黄海沉积物的贡献大于长江、锦江和荣山江。第一、三层沉积物对应着高海平面时期HⅠ、HⅡ海侵层,其矿物及元素特征均证明这两段岩芯形成时有“古冷涡”存在,古生物、水动力机制、孢粉、沉积物类型均为其存在提供了佐证。从而可推测,只要高海平面时期有黄海暖流和黄海环流出现则必定有“古冷涡”存在。NT2孔位于南黄海西南部(122o15.49’N,33o27.53’E),主要沉积了中更新世晚期以来的物质,孔深70m,发现矿物42种。据矿物的垂向分布特征及沉积类型,自上而下将NT2孔岩芯分为三个矿物段和六个矿物亚段。根据地球化学特征,又将NT2孔沉积物自上而下分为五层,基本上同矿物分段相对应。第一、二、四层化学元素分布特征相似,以富含多数氧化物和微量元素、贫Si、Na和Sr为特征,反应了近岸浅海环境,代表着HⅠ、HⅡ、HⅣ的高海平面时期;Na/Al和Na/K比值反应为温暖湿润的气候。化学元素、判别函数和富集因子均显示长江物质对物源的贡献大于黄河。稀土元素经北美页岩、上地壳和球粒陨石标准化的配分模式趋向于和长江更接近。第三、五层的化学元素分布相似,以贫Al、K、Ti、Mg、Corg、REE和微量元素,富Si、Ca、Na、Sr为特征。矿物组合和元素特征反应为海陆交互相,与古生物和孢粉反映的环境一致;Na/Al和Na/K比值反应了较干燥和寒冷的气候;元素、判别函数和富集因子显示黄河物质对物源的贡献大于长江。总之,晚更新世以来,NT1、NT2岩芯的矿物、地球化学、古生物和孢粉资料都反应了在温暖湿润的气候条件下和高海平面时期,长江物质对南黄海的贡献大于黄河、锦江和荣山江;而在干燥寒冷的气候条件和低海平面时期,黄河物质对南黄海物源的贡献大于长江、锦江和荣山江。更多还原

【Abstract】 Based on the research to the features of mineral and element geochemistry for sediment from two representational bores NT1 and NT2 in South Yellow Sea, the substance source and sedimentary environment in South Yellow Sea since Late Pleistocene are discussed in the paper. Bring to bear the mathematical statistic method, the sediment from the two bores and Yangtze River, Yellow River and Korean rivers is compared, and the contribution of the different rivers to substance source in South Yellow Sea is confirmed. The occurrence of two“ancient cold eddies”during the high sea level in South Yellow Sea since Late Pleistocene is demonstrated. The greigite (Fe3S4), manganocalcite and barite crystal, three kinds of marine authigenic minerals with environmental meaning, are first discovered in South Yellow Sea. The paper also expounds the features of authigenic pyrite and its environmental indication significance in the cold eddy sediment from South Yellow Sea.The Bore NT1 with 70 meters deep is located at the central gyre mud area (123o24.29’N,35o26.60’E) in South Yellow Sea, where the fine-grained substance has been deposited since Late Pleistocene. More than 40 kinds of minerals are identified in the core. According to the vertical distributional characteristics of minerals and elements and its sedimentary types, the core NT1 can be divided into five layers or five mineral segments (ten mineral sub-segments) from above to below. Based on the analysis and comparison on mineral– geochemistry characteristics of sediment from the core NT1, Yangtze River, Yellow River, Keum River and Yeongsan River, the paper can get the following results:In the aspect of substance source, the heavy minerals of the core sediment in the 1st Layer, 3rd Layer and 5th Layer (Segment) are mainly consisted of authigenic pyrite. The terrigenous mineral association is consisted of hornblende, epidote, dolomite, ilmenite and schistic minerals, which displays that it is closer to the mineral association in Yangtze River, and the sediment may mainly come from Yangtze River. Its element geochemistry characterizes the rich content of most metallic oxide, organic carbon and most minor elements. By means of the analysis to the elements, enrichment factors and discriminant functions of minor elements, it is shown that all kinds of characteristics are all close to that of Yangtze River, which illustrates that the sediment was mainly from Yangtze River. In the aspect of environment, for the concentration of magnanimous authigenic pyrite in the 1st Layer, 3rd Layer and 5th Layer, it reflects the weak hydrodynamic, reducing environment and marine deposit environment during high sea level period. The ratios of Na/Al and Na/K reflects that the warm and humid climate condition. Therefore, the contribution of Yangtze River to the sediment of Yellow Sea is more than Yellow River, Keum River and Yeongsan River. The heavy mineral associations of the 2nd Layer and 4th Layer (Segment) are mainly consisted of schistic minerals, calcite, epidote, hornblende and garnet, which displays that it is closer to the mineral association of Yellow River. This illustrates the sediment may mainly come from Yellow River. The element analysis reflects that the sediment in the 2nd layer and 4th Layer characterizes the rich Si, Ca, Na, Mn, P, and Sr, deficient Al, K, Ti, Mg, Fe, organic carbon, as well as fourteen kinds of minor elements except for Sr. Based on the analysis to the elements, enrichment factors and discriminant functions of minor elements, it is found that the contribution of substance from Yellow River is more than that from Yangtze River, Keum River and Yeongsan River. In the aspect of environment, the mineral associations and the ratios of Na/Al and Na/K in the 2nd layer and 4th Layer reflect stronger hydrodynamic condition and the sedimentary environment of shore, estuary and terrestrial facies, which represents the low sea level period and arider and cold climate condition. It is to say that the contribution of Yellow River to the sediment of Yellow Sea is more than Yangtze River, Keum River and Yeongsan River under the arider and cold climate condition during the low sea level period. The sediment of the 1st Layer and 3rd Layer separately corresponds to the marine strata HⅠand HⅡduring high sea level period, which characters of mineral and element all prove the existence of“ancient cold eddy”when the two core segments were formed, and the paleospecies, hydrodynamic mechanism, sporo-pollen and sedimentary types all provide the evidence for this. Thus, it can be inferred that the“ancient cold eddy”surely exists so long as the Yellow Sea warm current and Yellow Sea circular current appear during high sea level period.The Bore NT2 with 70 meters deep is located at the northwestern area (122o15.49’N,33o27.53’E) of South Yellow Sea, where the sediment has been formed since late Middle Pleistocene. More than 42 kinds of minerals are found in the core. According to the vertical distributional characteristics of the minerals and its sedimentary types, the core NT2 can be divided into three mineral segments and six mineral sub-segments from above to below. According to the geochemistry character, the sediment of Bore NT2 is also divided into five layers from above to below, which basically correspond to the above mineral segments. The distributional characters of chemistry elements from the 1st layer, 2nd layer and 4th layer are similar each other, which characterizes rich most oxides and minor element, deficient Si, Na and Sr. It reflects the offshore neritic environment and represents the high sea level period of marine strata HI、HII、HIV. The ratios of Na/Al and Na/K reflect the warm and humid climate. The chemistry elements, enrichment factors and discriminant functions all show that the contribution of Yangtze River to the substance source is more than Yellow River. The rare-earth element pattern tends to further approach Yangtze River via the normalization based on the North American shale, supracrust and chondritic meteorite. The chemistry elements of the 3rd layer and 5th layer distribute similarly, which characterizes deficient Al, K, Ti, Mg, Corg, REE and microelement, rich Si, Ca, Na and Sr. The characters of mineral association and elements reflect marine and terrestrial alternation facies, which is consistent with the environment that paleospecies and sporo-pollen also reflect. The ratios of Na/Al and Na/K reflect the arider and cold climate. The elements, discriminant functions and enrichment factors show that the contribution of Yellow River to the substance source is more than Yangtze River.In a word, the data about the minerals, geochemistry, paleospecies, and sporo-pollen in Bores NT1 and NT2 all reflect that the contribution of Yangtze River to the sediment in South Yellow Sea is more than Yellow River in the warm and humid climate condition and high sea level period, and the contribution of Yellow River to the substance source of South Yellow Sea is more than Yangtze River, Keum River and Yeongsan River in the arider and cold climate condition and low sea level period since Late Pleistocene.更多还原