Satu Hietala

Geological Survey of Finland | GTK

The Summanen structure is located in Central Finland and is one of Finland's 12 known meteorite impact structures. In 2017, the discovery of Summanen was based on numerous shatter cone boulders with planar deformation features (PDFs) and a circular electromagnetic anomaly, which is 2.6 km in diameter. The site was revisited in 2020 and 2022, and sh...

The impact origin of the Early Cretaceous (140.82 ± 0.51 Ma) 20‐km diameter Dellen structure was proven in the late 60s based on the discovery of planar deformation features (PDFs) in quartz grains. Although decades have passed, impactites found from the crater have not received much attention. Thus, this study provides a detailed petrological and...

The Keurusselkä structure is one of Finland's 12 meteorite impact structures—one of the world's oldest (1150 ± 10 Ma) and the largest of its kind in Finland. Findings of numerous well‐formed shatter cones in a wide area have helped define and prove Keurusselkä's impact origin. Keurusselkä is deeply eroded, making estimating its size challenging. Th...

A comprehensive summary of the up to date collected information (some unpublished), reseach and background to one of the large impact structures in Europe. Introduction of orographic maps. Test of alternative method for gravity interpretation based on strain distribution. Provides an integrated model of the lateral and depth extent of the impact st...

List of content to the book "The 20 km diameter Dellen impact structure, central Sweden".

We investigated the element fractionation of the sulfide mineral phase upon melt formation and its re-distribution within a silicate host rock during thermal exposure. Sulfide melt migration is responsible for a phenomenon termed shock-darkening (e.g., [1,2,3]) and the study material is an experimental analog to improve our understanding of pervasi...

Asteroids are spectrally diverse objects. This diversity is related mainly to their distinct mineralogical composition. However, parameters like temperature, phase angle and grain size additionally influence their classification. Processes like, e.g., shock pressure, post shock heating, and space weathering (SW; [1]) alter such initial asteroidal c...

Presentation slides of a seminar (in Estonian) given at Tartu University, Department of Geology, on 29th of April 2022. These are the latest results for the observations on dunite impregnated by FeS troilite at high temperatures (1325°C). The presentation gathers morphological observations, chemical observations, and chemical diffusion analyses be...

Stoichiometric troilite (FeS) is a common phase in differentiated and undifferentiated meteorites. It is the endmember of the iron sulfide system. Troilite is important for investigating shock metamorphism in meteorites and studying spectral properties and space weathering of planetary bodies. Thus, obtaining coarse-grained meteoritic troilite in q...

Abstract available at https://meetingorganizer.copernicus.org/EPSC2021/EPSC2021-34.html

Introduction: This work is a research continuation on shock-darkening of ordinary chondrites by iron sulfide shock melt vein migration into silicate cracks [1-5] and its implication to asteroid spectral properties [4,6]. We aim to study migration of sulfide melt to characterize properties that offer a better insight into shock-darkening through che...

Meteorite impact structures can provide important information on long-term denudation on the Earth's cratons. Impact structures in the Fennoscandian Shield contain rocks (i.e., impactites), that have developed during the collision, and, possibly, remnants of the pre-impact sedimentary rocks. The crater depressions may also be filled with post-impac...

The Earth’s cratons are traditionally regarded as tectonically stable cores that were episodically buried by thin sedimentary covers. Cratonic crust in southern Finland holds seven post-1.7 Ga tiered unconformities, with remnants of former sedimentary covers. We use the geometries of the tiered unconformities, along with previously dated impact str...

The Summanen structure (62°39.00N, 25°22.50E) is located within the Paleoproterozoic Central Finland Granite Belt, Fennoscandian Shield. The structure is hidden under Lake Summanen and not directly observable. It owes its discovery to low-altitude airborne geophysical data, which revealed a circular, ~2.6 km wide electromagnetic in-phase, and resis...

This report provides geologic background and site descriptions of a geotrail around Lappajärvi impact structure, western Finland. The site descriptions are available also in English. In the second edition (March 2018) some typos were corrected and accidentically missing references were added. The project website, including links to Google Maps (wi...

Earlier book on Finnish gemstones was published nearly 20 years ago. After that new finds have been made yearly. Mainly they have been reported in Finnish and typically in mineral club magazines whose circulation is quite narrow. Therefore, this new book was needed. It was written in both Finnish and English, because only very few articles have bee...

Söderfjärden impact crater, new results and new drilling plan S.HIETALA1*, L.J. PESONEN2, M. ANDERSÉN3AND P.EDÉN4 1Geological Survey of Finland, PO Box 1237, 70211 Kuopio, FINLAND (*correspondence: satu.hietala@gtk.fi 2Physics Dept, University of Helsinki, 00014 Helsinki, FINLAND 3Meteoria Söderfjärden Visitor Centre, Marenintie 294, 65410 Sundom,...

The book includes the materials collected by the participants of KA334 Mining Road Project of Karelia ENPI CBC Program during the process of preparation of a tourist route from the city of Petrozavodsk and its outskirts to the city of Outokumpu (Finland). The book contains descriptions of the most interesting and signifi cant sites of the territori...

В книгу вошли материалы, собранные участниками Проекта КА334 "MINING ROAD" Программы Karelia ENPI CBC в процессе подготовки туристического маршрута от города Петрозаводска и его окрестно- стей до города Оутокумпу (Финляндия). Книга включает описание наиболее интересных и значимых объектов на территории обеих стран и предназначена для тех читателей,...

New isotopic age data are presented for the Keurusselkä, Paasselkä, Suvasvesi South, and Karikkoselkä impact structures, Finland.

The Kirkkoranta pseudotachylitic breccia dike is the first finding of impact-related melt lithologies known from the deeply eroded Keurusselkä impact structure, Finland. 40Ar/39Ar dating yielded a late Mesoproterozoic (Stenian) age of the rock.

Mapping distribution of shatter cones in Keurusselkä impact structure has revealed that traces of impact can be seen in 14 km wide area. Keurusselkä is an old and deeply eroded impact structure where no rim or depression is left.

A new meteorite impact structure "Keurusselkä" was discovered in Central Finland in 2003 by S. Hietala and J. Moilanen (Hietala and Moilanen, 2004a, 2004b). The discovery was based on shatter cone findings in a circular area of some 10 km in diameter between the village of Kolho and the western shore of the lake Keurusselkä. Traces of remnants of t...

Previously unknown impact structure have been found in Finland. The 9.5 km wide Keurusselkä impact structure is 11th impact structure found in Finland so far. In situ shatter cones and PDFs in a breccia sample confirm the discovery.