Modern sedimentation processes in Lake Towuti, Indonesia, revealed by the composition of surface sediments
Modern sedimentation processes in Lake Towuti, Indonesia, revealed by the composition of surface sediments
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DOI：
10.1111/sed.12503
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发表时间：
2018-08
期刊：
影响因子：
3.5
通讯作者：
Ascelina K. M. Hasberg;S. Bijaksana;P. Held;J. Just;M. Melles;Marina A. Morlock;S. Opitz;J. Russell;H. Vogel;V. Wennrich
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文献类型：
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作者：
Ascelina K. M. Hasberg;S. Bijaksana;P. Held;J. Just;M. Melles;Marina A. Morlock;S. Opitz;J. Russell;H. Vogel;V. Wennrich
印度尼西亚苏拉威西岛上的Towuti湖位于印度太平洋暖池的中心。这个热带湖泊被超镁铁质（蛇绿岩）岩石和红土包围，形成了独特的铁质沉积环境。为了了解Towuti湖的现代沉积物沉积，从整个湖泊收集了一组84个湖面沉积物样品，并对样品进行了物理，化学，矿物学和生物成分分析。进行端元分析，以阐明现代沉积物的起源，运输和沉积过程。本研究发现，外来沉积物，其特征在于元素Mg，Fe，Si和Al的浓度，以及粘土和蛇纹石矿物，主要是由河流供应从五个不同的源区。粒度数据和陆源有机物的出现表明，在湖泊的南部和东北部，近海岸沉积物可能还受到质量浪费的影响。这至少部分是由于这些地区的斜坡特别陡峭。此外，沉积物的组成表明，沉积物输运到更深的部分湖泊，特别是在北方盆地，部分控制重力和密度驱动的过程，如浊流。相反，持续的湖流的定向沉积物输运似乎不那么重要。超贫营养湖泊中的有机物沉积虽然有限，但主要是由本地生产，但也有一些河流和重力供应的贡献。主要来自硅藻细胞壳和海绵骨针的生物二氧化硅沉积非常有限，仅集中在靠近海岸线的几个地区，这些地区的特点是沃茨较浅，但远离主要入口口处的高悬浮负荷地区。这项研究的结果建立在目前和发表的工作短活塞核心从Towuti湖。相反，这些结果将支持对沉积历史和过去气候和环境条件的解释，这些条件来自于2015年5月Towuti钻探项目获得的更长记录的组成，目前正在调查中。
Lake Towuti on Sulawesi Island, Indonesia, is located within the heart of the Indo‐Pacific Warm Pool. This tropical lake is surrounded by ultramafic (ophiolitic) rocks and lateritic soils that create a unique ferruginous depositional setting. In order to understand modern sediment deposition in Lake Towuti, a set of 84 lake surface sediment samples was collected from across the entirety of the lake and samples were analyzed for their physical, chemical, mineralogical and biological constituents. End‐member analyses were carried out to elucidate modern sediment origin, transport and depositional processes. This study found that allochthonous sediment, characterized by the concentrations of the elements Mg, Fe, Si and Al, as well as the clay and serpentine minerals, is dominated by fluvial supply from five distinct source areas. Granulometric data and the occurrence of organic matter of a terrestrial origin suggest that, in the southern and north‐eastern parts of the lake the near‐shore sediments may additionally be influenced by mass wasting. This is due at least partly to the particularly steep slopes in these areas. Furthermore, sediment composition suggests that sediment transport into deeper parts of the lake, particularly in the northern basin, is partly controlled by gravitational and density‐driven processes such as turbidity currents. Directional sediment transport by persistent lake currents, in contrast, appears to be less important. Organic matter deposition in the ultra‐oligotrophic lake, albeit limited, is dominated by autochthonous production, but with some contribution of fluvial and gravitational supply. Biogenic silica deposition, primarily from diatom frustules and sponge spicules, is very limited and is concentrated in only a few areas close to the shoreline that are characterized by shallow waters, but away from the areas of high suspension loads at the mouths of the major inlets. The results of this study build upon current and published work on short piston cores from Lake Towuti. Conversely, the results will support the interpretation of the depositional history and past climatic and environmental conditions derived from the composition of much longer records, which were obtained by the Towuti Drilling Project in May 2015 and are currently under investigation.