曹妃甸近岸及周边海区碎屑矿物组成特征及其环境意义

Environmental significance of detrital minerals and their composition in the Caofeidian inshore and adjacent sea

为探讨曹妃甸近岸及周边海区沉积物碎屑矿物组成特征以及曹妃甸大规模围填海工程对其影响,作者对2013年10月采自曹妃甸及周边海区的表层沉积物样品采用轻重矿物分离的方法进行了鉴定。结果表明:大规模围填海工程在改变曹妃甸岸线形态的同时也改变了其冲淤环境,使得碎屑矿物组分在大规模围填海前后发生一定变化。研究区的沉积物整体以轻矿物为主,平均含量为97.83%,其中曹妃甸近岸平均含量为95.57%;重矿物平均含量为2.17%,其中曹妃甸近岸平均含量为4.43%。研究区的重矿物优势矿物主要有普通角闪石、绿帘石和自生黄铁矿,其中普通角闪石所占比例在曹妃甸近岸达到最高值(36.41%);轻矿物的优势矿物主要有石英、斜长石和风化碎屑,其中石英所占比例也在曹妃甸近岸达到最高值(62.72%)。研究发现,曹妃甸近岸沉积物碎屑矿物相对含量增加而重矿物基本不变,这在一定程度上揭示了大规模人工围填海工程对曹妃甸近岸及周边海区沉积环境的影响。

To investigate the impacts of large-scale reclamation engineering on the sedimentary environment, sur-face sediment samples collected from the deposits at the Caofeidian inshore and adjacent sea during 2013 were analyzed to determine their detrital mineral composition by separating the light and heavy minerals. The results show that large-scale reclamation engineering has not changed the form of the Caofeidian coastline but has changed the sedimentary environment. Simultaneously, the components of the detrital minerals for large-scale changed be-fore and after reclamation construction. The sediment in the study area is mainly composed of light minerals, with an average content of 97.83% and 95.57% in the Caofeidian inshore. The average content of heavy minerals was 2.17% and 4.43 % in the Caofeidian inshore. The predominant heavy minerals were hornblende, epidote, and authigenic pyrite, of which hornblende content was the highest （36.41%）. The predominant light minerals were quartz, plagioclase, and erosion materials, of which quartz content was the highest （62.72%）. This study indicates that the variations in the detrital mineral composition of the surface sediments of the Caofeidian inshore and adja-cent sea before and after large-scale reclamation can reflect the influences of reclamation on the sedimentary envi-ronment of the study region to some extent.