Abstract
The crustal and upper mantle structures of the Shield on the regional scale were
investigated using the data of the POLENET/LAPNET passive seismic array and
the previously published models of active and passive seismic experiments in the
study area. This area is centred in northern Finland and it extends to surrounding
areas in Sweden, Norway and northwestern Russia. The bedrock there is mostly of
the Archaean origin and the lithosphere of the region was reworked by two orogenies
during Palaeoproterozoic.
One of the results of the thesis was a new map of the Moho depth of the study area,
for which new estimates of the crustal thickness were obtained using receiver function
method and complemented by published results of receiver function studies and controlled
source seismic profiles. The map differs from the previously published maps in
two locations, where we found significant deepening of the Moho. The 3D structure of
the upper mantle was studied using teleseismic traveltime tomography method. The
resulting model shows high seismic velocities below three cratonic units of the study
area, which may correspond to non-reworked fragments of cratonic lithosphere and a
low velocity anomaly separating these cratonic units from each other.
The regional scale studies were complemented by two smaller scale studies in upper
crust level using combined interpretation of seismic profiling and gravity data. These
studies were centred on Archaean Kuhmo Greenstone Belt in eastern Finland and
central Lapland in northern Finland located in the crust reworked during Palaeoproterozoic.
Both areas are considered as prospective ones for mineral exploration. Both
studies demonstrate the advantage of gravity data inversion in studying 3D density
structure of geologically interesting formations, when the Bouguer anomaly data is
combined with a priori information from petrophysical and seismic datasets.
| Identifer | oai:union.ndltd.org:oulo.fi/oai:oulu.fi:isbn978-952-62-1068-1 |
| Date | 02 December 2015 |
| Creators | Silvennoinen, H. (Hanna) |
| Contributors | Kozlovskaya, E. (Elena), Kaikkonen, P. (Pertti) |
| Publisher | University of Oulu |
| Source Sets | University of Oulu |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/doctoralThesis, info:eu-repo/semantics/publishedVersion |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess, © University of Oulu, 2015 |
| Relation | info:eu-repo/semantics/altIdentifier/pissn/1456-3673 |
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