Advanced Materials Research
ISSN: 1662-8985, Vols. 989-994, pp 1384-1387
doi:10.4028/www.scientific.net/AMR.989-994.1384
© 2014 Trans Tech Publications, Switzerland
Submitted: 2014-05-25
Accepted: 2014-05-30
Online: 2014-07-16
Preservative features of the fossils in bauxite deposit of WZD area,
Northern Guizhou, China
Tao Cui
College of Resources and Environmental Engineering, Guizhou Institute of Technology, Guiyang,
550003, China
[email protected]
Keywords: WZD area; Bauxite; fossils
Abstract: It is hardly to discovery fossil from the bauxite in Wuchuan -Zheng, an-Daozhen (WZD)
area, northern Guizhou, China. But the new study suggests, containing a small amount of plant
debris from massive bauxite in the lower part of the ledge. Preservative features of fossils in WZD
bauxite indicates: metallogenetic materials experienced a transport process; sedimentary
environment is reduced; fossils only preserved in the massive bauxite, that fossils in other types of
ores were destroyed in the late oxidation modification. Metallogenic environment of bauxite has
experienced two kinds of state- reduction and oxidation. The lack of animal fossils; bauxite, reveal
that the metallogenic environment is acidic, resulting in animal fossils are dissolved and
hard to save.
Introduction
There is abundant bauxite in the WZD area. For a long time many experts and scholars have
research on the bauxite of rocks and minerals, chemistry, sedimentary environment, provenance,
mineralization age [1-6]. As bauxite in other areas WZD bauxite just has small fossils, but these
small fossils would supply important metallogenetic information for research. There are small
amount of phytolite in the WZD bauxite, this paper has an analysis on the preservative features of
these fossils to research metallogenetic environment and metallogenetic process of the WZD
bauxite.
Geological setting
WZD bauxite is located in Wuchuan, Zheng’an and Daozhen County, northern Guizhou, which is
an important part of centre Guizhou-southern Chongqing bauxite belt [7]. The regional tectonics
position of the study area is in the fold belt in northern Guizhou of the upper Yangtze Block[8]. The
main strata in WZD area from the oldest to the youngest including: Cambrian, Ordovician, Silurian,
Permian, Triassic and Jurassic. Cambrian is mainly distributed in the core of anticlines, Triassic and
Jurassic are mainly distributed in the core of synclines. Bauxite is underlying the LiangShan
formation(P2l) or Qixia formation(P2q) of the middle Permian, overlying the HuangLong
formation(C2h) of upper Carboniferous or the Hanjiadian formation of the lower Silurian(S1hj).The
bauxite is stratiform and unconformable with the underlying and overlying strata. Fig.1 shows that
the distribution of the bauxite was controlled by nine synclines. The thickness of the bauxite is
0.68-15.7m, the profile can be divided into two lithology parts: the upper part is aluminous rock,
dominated by high grade bauxite or half grade bauxite; the lower part is low grade bauxite.
According to the lithological and textural properties, the natural types of bauxite deposit can
roughly be subdivided into four categories: massive bauxite, oolithic bauxite, clastic bauxite and
earthy bauxite.
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Advanced Materials Research Vols. 989-994
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Fig. 1(a)Locality map of Guizhou,(b)The map showing the location of the study area,
(c)Geology map of the WZD area in northern Guizhou
Fig.2 Column shows the location of fossils [8]
Preservative features of the fossils
Fig.2 shows that plant fragment of fossils just preserved in the massive bauxite in the lower part of
the producing formation, there are no fossils preserved in other types of bauxite. Plant fossils are
elongate or scaly, length of fossils can over 3cm (Fig.3,e,f). Plant fossils are commonly fragmented
indicates that the formation of these fossils experienced a transported deposit process.
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Materials Science, Computer and Information Technology
Though WZD bauxite just has small fossils, these small fossils would supply important
metallogenetic information for research. Forming process of fossils need reduced environment,
WZD bauxite is grey and contain some plant fragment fossils shows that sedimentary environment
is reduced. There are no plant fragment fossils preserved in four types bauxite except massive
bauxite, obviously fossils cannot selectively preserve. In the period of original deposition four kinds
of bauxite in the WZD area contain plant fragment but plant fragment was destroyed by later
metallization. Comparison of the massive bauxite and other three types of bauxite, there are obvious
difference in these bauxite (Fig.3). Fig.3 shows that Massive bauxite is grey – green which is the
strongest reduced color in four type bauxite. Massive bauxite is more dense and smooth than other
kinds of bauxite. In the forming process of oolithic, earthy and clastic bauxite have experience a
severe transform that resulting in fossils be destroyed. Metallogenic environment is not constant but
altered in reduction and oxidation. There are no zoolite in the bauxite, it demonstrates that
Metallogenic environment is acidic so animal remains with calcareous skeleton cannot be preserved
but coaly plant remains can be preserved.
Fig.3 Fossils in the WZD bauxite: a. massive bauxite without fossil; b. clastic bauxite without fossil;
c. oolithic bauxite without fossil; d. earthy bauxite without fossil; e and f. massive bauxite contain
fossils
Conclusion
The main conclusions from this study are summarized as follows:1)There are some small
fragments of plant fossils in the lower part of producing formation; 2) In the period of Metallogenic
process metallogenic environment is not constant but altered in reduction and oxidation; 3)
Metallogenic environment is acidic cause only plant remains can be preserved as fossils.
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Acknowledgment
This work was supported by the Guizhou Collaborative Innovation Center of Strategic Minerals
Resource Development, Guizhou Institute of Technology, Guiyang, 550003, China and the project
of analysis on geochemical behaviors of Platinum group elements in Emeishan basalt
(XJGC20131204), Guizhou Institute of Technology.
References
[1] G.H. Wu, Z.G. Jin, Y. Bao: J.Geology and Prospecting,Vol.44(2008),P.34 (in Chinese)
[2] Z.G. Jin, G.H. Wu, Y.Y. Zhao:J.Mineral Source and Geology,Vol.23(2009),P.139 (in Chinese)
[3] K.H. Yin: J. Acta Sedmentological Sinica, Vol.27(2009),P. 455 (in Chinese)
[4] Z.H. Han: J. Mineral Resource and Geology,Vol.22(2008),P. 430 (in Chinese)
[5] Z.Y. Lei and Y.C. Liao: J. Western Prospecting Engineering, Vol.18(2007), P. 96 (in Chinese)
[6] X.M. Wang, Y.Q. Jiao and Y.S, Du: J. Journal of Geochemical Exploration, Vol. 133(2013),
P.108.
[7] P. Liu: J. Guizhou Geology, Vol. 18(2004), P. 240(in Chinese).
[8] T. Cui, Y.Q. Jiao, Y.S. Du: J. Journal of palaeogeography, Vol.16(1),P.9(in Chinese).