Using satellite data for exploration of Earth bowels and identification of tectonically unstable
structures K.A.Boyarchuck VNIIEM,
A.I Gorshkov, I.V.Kuznetsov, E.P.Piotrovskaya IIEPT, L.V.Miloserdova N.I.Maloushina TerraMentor Ltd, Greece The problem of seismic - geological safety of large industrial objects
is directly related to the tectonically instable areas of the Earth's crust,
where the seismic events may occur. The specialized fracture maps have a regional
character, so they cannot help to detect at the local level if a fault is
ancient and inactive or "alive" and therefore dangerous. Satellite
imaging of high and medium resolution is a unique source of information for
reliable detection of such fault-and block structure of a territory under study
and for determination of rank relations between tectonic blocks. The existing
experience of successful interpretation of medium resolution space images for
geological prospecting may be also applied for revealing of tectonically
instable structures, i.e. for detection of all "living" fractures of
any mapping scale and in real time. Faults and fractures are very important
structural elements of the lithosphere, because: -
they are zones of maximal inhomogenity
of the Earth's crust, and the most intensive development of the Earth's crust
motions, heat flow anomalies, etc., may be expected there; -
they are zones, where the Earth's
crust denseness is interrupted, the litho-static pressure is decreased there,
and it makes penetration of fluids inside such zones easier; -
along such zones the Earth's crust
tenses are released, and therefore different-way movements of earth's blocks
happen there; -
during fault forming, various
near-fault folds appear, and they may play a role of hydrocarbon traps; -
jointing is widely developed in the
Earth's crust, it is an important parameter responsible for permeability of
geological medium. Using the data related regularities of jointing
distribution, it is possible to predict the jointing in case of lack of other
factual data. At
the same time, the role of faults in geological structure in many geological
constructions, especially in cases when the space images were not used, is
taken into account not completely. Before, only large structures having
sufficient movements of blocks along fractures (which ma be mapped in the
survey's scale) were mapped. Such approach is clearly incorrect, especially for
oil & gas geology, because no fewer roles in it play low-amplitude and
amplitude-less fracture zones and zones of decreased toughness of rocks. It is
also needed to take into account that dropping of fault-and-block structure
usually follows to creation of smooth tectonic models, which cannot be proved
by detailed seismic and drilling. Space images
provide information for identification of geo-structural elements, geochemical
anomalies, and zones of hazardous geodynamic and exogenous processes.
Interpretation results combined with geological and geophysical data may serve
a base for prediction of deep structures, because information related
geological structures is manifested by various elements and components of
landscapes. Space images are the unique
source of information for reliable delineation of the fault-and-block structure
and the structural skeleton of a region and hierarchical relationships between
tectonic blocks. For geodynamic analysis, space
images have to be investigated consequently in different scale (with different
resolutions). The object under study has to be considered as an entire system
in working scale; in a larger scale the entire objects are the elements of such
objects, and in smaller scale the object become a part of a larger system.
Simultaneous use of space images having different resolution, chosen in a
special way, enables to map the geological bodies of various ranges and to
determine the relationships between such bodies. Interpretation of space images
plays an important role in oil & gas exploration. It is determined by the
fact that oil and gas deposits located in deep structures of Earth's crust due
to systemic properties of the Earth are manifesting in different forms at the
day surface as anomalies of modern landscapes, and they ma be recognized in
remote sensing data. When it is impossible to recognize the deposits, usually
possible determining the plane location of structures probably including the
deposits or précising the area geological structure, especially from
point of disjunctive dislocations. Thus, at the regional
prediction stage, by space image data the main identities of the area's
fault-block tectonic are to revealed; tectonic and geological zoning of oil
fields is carried out, and the main directions and priority objects for further
exploration are determined. At the stage of oil accumulation area investigation
by space image data the sub-regional and zone structural relationships between
different formations is revealed; geological zoning of oil fields is
précised; the most promising traps are detected. At the stage of
exploratory prospect and preparation for exploration drilling, the mode
of oil-bearing complexes occurrence is revealed; the promising trap and their
main identities are determined. At the stage of deposit prospecting, by space
images the boundaries of the oil prospecting objects are précised and
the areas with improved filtration properties (fractured zones) are revealed. Use of satellite data for ore
deposits exploration is based on the fact that many metal deposits tied to
magmatic and volcanic massifs and with secondary changed rocks (pneumatolytic
and hydrothermal processes are usually localized in complicate structures). So,
in surface and near-surface conditions, due to exogenous processes, the
mineralization zones usually form specific macro- and micro-relief differing
from the surrounding morphological forms. In the images, usually the faults are
clearly seen; they are very important as for localization of deposits as for
further displacing of deposits' parts. Existing successful experience
on use of space images for revealing of fault-and-block structure of
territories in area of mineral exploration may be also applied for revealing of
tectonically unstable territories connected to faults, which are the most
probable areas for realize of tenses in Earth's crust. It is particularly remarkable
that the single approach may be used as for revealing of areas, where the fast
tectonic movements (seismic events) may occur as for revealing of slow
movements like creep. In this research, the method
is presenting, which combines use of geological, geomorphic, and space data
with techniques of pattern recognition. The method allows identifying
seismogenic structures of local scale and determining their characteristic
geological, geomorphic, and geophysical features. The method is based on the concept
that large earthquakes correlate with morphostructural nodes forming in areas
of morphostructural blocks junction. Nucleation of strong earthquakes at
morphostructural nodes was confirmed for many seismoactive regions of the
world. The same method was also used for identification of ore bearing nodes in
the Tethys belt. |
© 1995-2008 Kazan State University