淮河流域沉积物碎屑矿物组成和单颗粒矿物地球化学的物源指示：以石榴石、角闪石和锆石为例

The huaihe river, located between the two great rivers of the Yangtze river and Yellow River, is an important river in central China. The provenance of sediments in the river is a key factor in reconstructing the paleoclimate, paleogeography and tectonic history in a region. Detrital minerals have been widely used in studying the sediment provenance, including light minerals and heavy minerals. However, minerals compositions of river sediments are controlled by many complex factors, including mineralogical compositions in source rocks, grain size, sediment sorting, post depositional diagenesis. In this case, significant research has focused on single mineral geochemistry analysis and this is the most efficient method to discriminate sediment sources. In this study, we analysis the mineralogical characteristics of the sediments, combined with the area geology, stratum, rock and the climate and environmental of the huaihe River basin, to study the provenance of the huaihe River sediment and the influencing factors of the mineral assemblage.The sediment samples will be collected from the surface of the main stream and tributary of the huaihe River system and the detrital minerals assemblage were analysised. Moreover, the geochemistry of single minerals of as garnet, amphibole and U-Pb geochronology and Lu‒ Hf isotopic systems of zircon will be intensively discussed in the provenance studies of the Huaihe river sediments. The specific objectives of this study were to identify the major controlling factors that influence the bulk sediment minerals compositions, and identify the geochemical proxies of single minerals that can be used to identify sediment sources in the Huaihe River, and evaluate the contributions of tributary to the main stream sediments in Huaihe River systems.

淮河位于长江与黄河两条大河之间，是中国中部一条重要的河流。河流沉积物的物源在在重建区域古环境、古地理和构造历史演化的研究具有重要意义。碎屑矿物现在被广泛应用于沉积物物源研究，主要包括轻矿物和重矿物。然而，河流沉积物矿物组成受到多种因素的影响，包括母岩的矿物组成、粒度、沉积物分异和沉积后的成岩作用等。在这种情况下，对单颗粒矿物进行地球化学分析可以很好的分析沉积物的物源。在本研究主要通过沉积物矿物特征，结合区域地质、地层、岩石和气候环境，来研究淮河流域沉积物的物源及矿物组合影响因素。采集淮河流域各支流和干流的表层沉积物并对其进行矿物组合分析。此外，选取单颗粒的石榴石和角闪石进行地球化学分析以及对锆石进行U-Pb测年和Hf同位素分析，来进行淮河流域沉积物的物源研究。这项研究的目的是确认淮河流域沉积物矿物组合的主要控制因素，沉积物物源识别的单矿物地球化学指标以及淮河流域支流对干流沉积物影响。

中小河流流域面积小，风化作用以及沉积过程与大河流域具有明显不同，对区域环境变化响应敏感，易受极端气候事件和人类活动的明显影响，在全球环境演化和物质循环中起着重要作用。本项目主要研究淮河流域表层沉积物碎屑矿物组合、单颗粒矿物石榴石和角闪石地球化学特征，锆石矿物U-Pb年龄及Hf同位素特征，探讨其沉积物物源和流域演化特征。.淮河流域沉积物整体分选和磨圆都较差，多数矿物呈次棱角状至次圆状；轻矿物组成为斜长石、石英和钾长石，重矿物组成为普通角闪石、磁铁矿、石榴石、辉石、绿帘石和黑云母，稳定矿物含量相对较少；而不稳定矿物相对较多，矿物成熟度低。普通角闪石、石榴石、绿帘石和锆石等透明重矿物具有密度大、抗风化能力较强的特征，且它们具有相似的水动力特征，因此可以选取相对含量高、密度接近的颗粒状矿物，用它们之间的比值来探讨沉积物的物源。如普通角闪石/绿帘石，普通角闪石/石榴石，石榴石/绿帘石等，这种方法在探讨黄河三角洲~1.9Myr以来的沉积物物源中得到很好的应用。.淮河流域沉积物石榴石和角闪石矿物主要来源于上游地区太古代和元古代的基岩的风化产物。单颗粒角闪石和石榴石矿物地球化学数据表明，淮河流域角闪石主要为镁钙闪石和铁角闪石；石榴石主要为铁镁榴石和铁锰榴石。矿物成因主要为基性和中性岩浆岩，岩浆以幔源为主，壳幔混合源次之；其次变质成因，变质成因的角闪石和石榴石生成于中温-中高温、高压-低压的变质环境。淮河流域锆石年龄分布广泛，包括>2600Ma、900~1800Ma、600~900Ma、400~600Ma和<300Ma。角闪石、石榴石地球化学数据，淮河流域沉积物主要来源于秦岭-大别-苏鲁造山带，其次为华北板块。少量的扬子板块、东昆仑造山带、柴达木板块及祁连山造山带相近的物质主要分布于淮河流域的中下游地区，可能是受到了黄河沉积物影响的结果。.目前，淮河流域的研究相对较少，限制了流域水环境管理与健康生态系统的维护，不利于流域可持续发展管理和环境灾害的评估与预防，需要进一步加强研究。