Manganese nodules mesozoic deep-sea deposits off some Indonesian Islands

Concretions of manganese have been discovered by the geological expedition to the islands of the Timor group in 1910—1912 in triassic and jurassic deep-sea deposits, on the Island of Timor, and also well developed in similar jurassic deposits on the island of Rotti, and previously, in 1894, the author noticed them in abysmal deposits of the pre-cretaceous probably jurassic Danau formation, occurring in West and East Borneo. On the island of Rotti nodules of manganese were found in several localities in siliceous limestones, marls, siliceous and calcareous clayshales along with concretions and nodules of chert of jurassic age, full of tests of radiolaria.

1910—1912年，地质考察队在帝汶群岛（Timor Group）的三叠纪、侏罗纪深海沉积层以及帝汶岛（Timor）境内，发现了锰结核（manganese concretions）；此类锰结核在罗蒂岛（Rotti）的同期侏罗纪沉积层中亦发育良好。1894年，作者曾在分布于西婆罗洲与东婆罗洲的白垩纪前（大概率属侏罗纪）达瑙组（Danau Formation）深海沉积中发现这类结核。在罗蒂岛，锰结核产于多个产地的硅质石灰岩、泥灰岩、硅质及钙质粘土页岩中，与侏罗纪时期的燧石结核及结核状燧石伴生，这些燧石中富含放射虫（Radiolaria）的硬壳。