Similar articles

Abstract: Evidences for the existence of ferromanganese crust boundary were found for the first time during the survey of the “DA YANG YI HAO” Vessel 2003. Some typical characteristics of the boundary are summarized and the significances of the finding of the boundary are included in the genesis discussion. Ore prospecting and assessment of the crust resources are described in this paper. The morphologic and extending characteristics of the crust boundary led to the recognition of two types of crust boundary: interpenetration crust boundary and closed crust boundary. According to the distribution and types of the crust, however, the boundaries are classified into three types: the boundary between ferromanganese crust and detrital sediment, the boundary between tabular crust and seamount nodules, and the boundary between tabular crust and rudaceous crust. This study revealed that the boundary between tabular crust and nodules was not formed under different regional environments but formed under different nucleation potential barriers between different initial growth (nucleation and germination) processes and between solid rocks and loose sediments. The rudaceous crusts are controlled spatially by fracture zones and the crusts’ boundaries are controlled by the seamount structure and landform. The discovery of the crust boundaries reveals the crust’s ‘negative growth’ phenomena (especially for some seamount nodules). The boundary investigation can be helpful in identifying the existence of tabular crust covered by detrital sediments and in calculating the area covered by the crust. The resource calculation error and the resource quality as well as resource exploration degree can be assessed through the survey of crust boundary.

[1] Akira, U., Masao, S., 1997. Distribution and composition of marine hydrogenentic and hydrothermal manganese deposits in the northwest Pacific. Manganese Mineralization: Geochemistry and Mineralogy of Terrestrial and Marine Deposits, Geological Society Special Publication, 119:177-198.

[2] Burnett, W.C., Morgenstein, M., 1976. Growth rates of Pacific manganese nodules by uranium-series and hydration-rind dating techniques. Earth Planet. Sci. Lett., 33:208-218.

[3] Henderson, G.M., Burton, K.W., 1999. Using (²³⁴U/²³⁸U) to assess diffusion rates of isotope tracers in ferromanganese crusts. Earth and Planetary Science Letters, 170:169-179.

[4] Krishnaswai, S., Mangini, A., Thomas, J.H., 1982. ¹⁰Be and Th isotopes in manganese nodules and adjacent sediments: nodule growth histories and nuclide behaviour. Earth Planet. Sci. Lett., 59:217-234.

[5] Lyle, M., 1982. Estimating growth rates of ferromanganese nodules from chemical compositions: implication for nodule formation processes. Geochem.Et Cosmoschem. Acta, 46:2301-2306.

[6] Moore, W.S., Ku, T.L., Macdougall, V.M., Burns, V.M., 1981. Fluxes of metals to a manganese nodule: radiochemical, chemical, structural, and mineralogical studies. Earth Planet. Sci. Lett., 52:151-171.

[7] Qian, J., Wang, X., 1999. The study on the formation ages and the growth rates of the polymetallic nodules in the East Pacific Ocean. Donghai Marine Science, 17(3):39-45 (in Chinese).

[8] Qian, J., Xu, Z., Wang, X., 1990. Research on growth rates of manganese nodules from north Pacific. Acta Sedimentologia Sinica, 8(1):122-128 (in Chinese).

[9] Sharma, P., Somayjulu, B.L.K., 1982. ¹⁰Be dating of large manganese nodules from world oceans. Earth Planet. Sci. Lett., 59:234-244.

[10] Usui, A., 1979. Minerals, Metal Contents and Mechanisms of Formation of Manganese Nodules from the Central Pacific Basin. In: Rischoff, J.L., Piper, D.Z. (Eds.), Marine Geology and Oceanography of the Pacific Manganese Nodule provinces. Plenum Publ. Co., Tokyo, p.651-679.

[11] Von Stackelberg, U., Beiersdorf, H., 1991. The formation of manganese nodules between the Clarion and Clipperton Fracture zones southeast of Hawaii. Mar. Geol., 98:411-423.

[12] Yao, D., Zhang, L.J., Xu, D.Y., Liang, H.F., 1994. Growth of ferromanganese nodules and crusts: a theoretical hypothesis. Marine Geology & Quaternary Geology, 14(2):105-108 (in Chinese).

[13] Zhang, F.Y., 2001. Evaluation Principle and Delineation Method of Polymetallic Nodule Resources. China Ocean Press, Beijing, p.17-120 (in Chinese).

[14] Zhang, L.J., Yao, D., Cui, R.Y., Qi, C.M., 1998. A discussion on the mineralization of ferromanganese deposits on the sea floor. Marine Geology & Quaternary Geology, 18(2):75-80 (in Chinese).