The second category of biomineralization, the BIOLOGICALLY CONTROLLED MINERALIZATION, describes the mineralization process which is guided along bio-seeds
and organic matrices; those biomolecules control initiation and growth of the
biominerals, their morphology, and also the velocity of the mineralization process
(Weiner and Dove 2003).
A special form of biologically controlled mineralization, ENZYMATICALLY CONTROLLED MINERALIZATION (Fig. 4.3e), has been described for the biosilicification
process in siliceous sponges (see: M€ uller et al. 2007b; Schr€ oder et al. 2008). In these
animals (Demospongiae and Hexactinellida), the enzyme silicatein (Cha et al.
1999; Morse 1999; Krasko et al. 2000; M€ uller et al. 2008a) is catalytically involved
in the formation of bio-silica (M€ uller et al. 2007a; Wang et al. 2008) and also
functions as organic scaffold for the inorganic polysilicate mineral (M€ uller et al.
2008b; Wang et al. 2008). Hence this enzyme acts as bio-seed and as organic
matrix.
In contrast to biomineralization, CHEMICAL MINERALIZATION describes the chemical and physical processes driving accumulation of new inorganic material from
solution; Fig. 4.3c. This process is controlled by the initial mineral growth rate,
the magnitude of supersaturation of the inorganic precursors as well as the temperature and might be ascribed to a first-order surface reaction kinetics and the
respective activation energy of the chemical reaction (Persson et al. 1995). At the
present state of knowledge, hydrothermal vents are formed by mineralization
processes only (Fig. 4.3c).
4.4 Mineralization/Biomineralization Processes During
Formation of Polymetallic Nodules [Mn-Nodules]:
Biologically Induced Mineralization
4.4.1 Deposits
The polymetallic nodules are mainly formed in deep water (4,000–5,000 m) within
the sediment–water interface. The age of the nodules is about 15 MYR (Somayajulu
2000). In general, they grow extremely slow, one atomic layer per year ([Kerr
1984] % 1 mm Ma
À1 ) and start to form on nuclei/seeds which are not only
weathered volcanic rocks or pumice (see: Glasby 2006) but may be also of biogenic
origin (bio-seeds) (Wang et al. 2009b). In contrast to the deep-sea polymetallic
nodules, the ferromanganese nodules in the shallow marine environments, e.g., in
the Baltic Sea (Zhamoida et al. 1996), have a rather high growth rate
(8 Â 10
3 mm Ma
À1 [Anufriev and Boltenkov 2007]). Large deep-sea resources
of polymetallic nodules have been localized in the Pacific Ocean (e.g., Clarion/
Clipperton zone), the Southern Ocean/Antarctic Convergence, and the Peru Basin
(Kawamoto 2008). The marine environment, in which “polymetallic” nodules are
formed, contains the constituents of the nodules, the transition metals Mn and Fe as
4 Biogenic origin of nodules and crusts
83
and organic matrices; those biomolecules control initiation and growth of the
biominerals, their morphology, and also the velocity of the mineralization process
(Weiner and Dove 2003).
A special form of biologically controlled mineralization, ENZYMATICALLY CONTROLLED MINERALIZATION (Fig. 4.3e), has been described for the biosilicification
process in siliceous sponges (see: M€ uller et al. 2007b; Schr€ oder et al. 2008). In these
animals (Demospongiae and Hexactinellida), the enzyme silicatein (Cha et al.
1999; Morse 1999; Krasko et al. 2000; M€ uller et al. 2008a) is catalytically involved
in the formation of bio-silica (M€ uller et al. 2007a; Wang et al. 2008) and also
functions as organic scaffold for the inorganic polysilicate mineral (M€ uller et al.
2008b; Wang et al. 2008). Hence this enzyme acts as bio-seed and as organic
matrix.
In contrast to biomineralization, CHEMICAL MINERALIZATION describes the chemical and physical processes driving accumulation of new inorganic material from
solution; Fig. 4.3c. This process is controlled by the initial mineral growth rate,
the magnitude of supersaturation of the inorganic precursors as well as the temperature and might be ascribed to a first-order surface reaction kinetics and the
respective activation energy of the chemical reaction (Persson et al. 1995). At the
present state of knowledge, hydrothermal vents are formed by mineralization
processes only (Fig. 4.3c).
4.4 Mineralization/Biomineralization Processes During
Formation of Polymetallic Nodules [Mn-Nodules]:
Biologically Induced Mineralization
4.4.1 Deposits
The polymetallic nodules are mainly formed in deep water (4,000–5,000 m) within
the sediment–water interface. The age of the nodules is about 15 MYR (Somayajulu
2000). In general, they grow extremely slow, one atomic layer per year ([Kerr
1984] % 1 mm Ma
À1 ) and start to form on nuclei/seeds which are not only
weathered volcanic rocks or pumice (see: Glasby 2006) but may be also of biogenic
origin (bio-seeds) (Wang et al. 2009b). In contrast to the deep-sea polymetallic
nodules, the ferromanganese nodules in the shallow marine environments, e.g., in
the Baltic Sea (Zhamoida et al. 1996), have a rather high growth rate
(8 Â 10
3 mm Ma
À1 [Anufriev and Boltenkov 2007]). Large deep-sea resources
of polymetallic nodules have been localized in the Pacific Ocean (e.g., Clarion/
Clipperton zone), the Southern Ocean/Antarctic Convergence, and the Peru Basin
(Kawamoto 2008). The marine environment, in which “polymetallic” nodules are
formed, contains the constituents of the nodules, the transition metals Mn and Fe as
4 Biogenic origin of nodules and crusts
83