TITLE:
Research and Application of Micromotional Exploration in the Middle-Lower Yangtze Metallogenic Belt of China
AUTHORS:
Xiaoqian Sun, Xinfu Li
KEYWORDS:
H/V Spectral Ratio, Spatial Autocorrelation (SPAC), Middle-Lower Yangtze Metallogenic Belt, Sedimentary Thickness
JOURNAL NAME:
International Journal of Geosciences,
Vol.12 No.10,
October
29,
2021
ABSTRACT: Micromotion is the daily tiny vibration of the earth’s
surface. Micromotional exploration can use the surface wave information of
micro motion to study the shallow structure of underground media. In this study,
we collected microtremor data at 68 stations in the Middle-Lower Yangtze
Metallogenic Belt (MLYMB) and determined the resonant frequency and obtained
the distribution of sedimentary thickness in this area by using H/V spectral
ratio. According to the results of H/V, the sedimentary layer in the basin is
thick, and the predominant frequency of the basin is 0.05 - 0.1 Hz. There
are no obvious lateral changes in the impedance interface between bedrock and
sedimentary layer in this area. The basement of Tongling, Anqing and Luzhou
mining areas and their adjacent areas is Kongling-Dongling type basement, which
is composed of a set of metamorphic core complex. The predominant frequency is
0.05 - 0.1 Hz. The sedimentary thickness gradually thinned from 3800 m in the
west to 2100 m in the East. Moreover, this article used SPAC (spatial autocorrelation)
method to obtain the S-wave velocity structure of the mining area near Luzong.
The SPAC method reveals that the depth of the interface between the loose
sediments and the volcanic rocks is about 600 m in the study area near the
Luzhou mining area in the Middle-Lower Yangtze Metallogenic Belt, and the
average depth of the interface between the volcanic rock section and the
intrusive complex section is about 1000 m. The
thickness of the intrusive rock is more than 2500 m. Tourmaline
is developed in the interior of the intrusive rock, which may have better
exploration value.