Skip to main content

LUP Student Papers

LUND UNIVERSITY LIBRARIES

Echoes of impact: A petrographic analysis and classification of impact breccias from Hummeln, Sweden.

Svensson, Ludvig LU (2024) In Dissertations in Geology at Lund University GEOL02 20241
Department of Geology
Abstract (Swedish)
The Hummeln structure is a relatively recently confirmed impact structure located in the northeastern
part of the province of Småland in Sweden (57.37347°N 16.25084°Ö). Due to its relatively recent confirmation,
detailed petrographic studies regarding shock metamorphism and shock metamorphic features in the Hummeln-1
drill core are lacking. The drill core is the only drill core from the structure and reached about ~164.25 meters,
measured from the lake surface. This study describes, classifies, and discusses three rock types from the lower part
of the drill core, and their relationship to the impact event. Three thin sections from these rock types were analysed
using polarizing microscopy, two of which were also analysed using... (More)
The Hummeln structure is a relatively recently confirmed impact structure located in the northeastern
part of the province of Småland in Sweden (57.37347°N 16.25084°Ö). Due to its relatively recent confirmation,
detailed petrographic studies regarding shock metamorphism and shock metamorphic features in the Hummeln-1
drill core are lacking. The drill core is the only drill core from the structure and reached about ~164.25 meters,
measured from the lake surface. This study describes, classifies, and discusses three rock types from the lower part
of the drill core, and their relationship to the impact event. Three thin sections from these rock types were analysed
using polarizing microscopy, two of which were also analysed using scanning electron microscopy (SEM). From
the top down, the first rock (Breccia 1) is a monomict cataclastic impact breccia located between 159.14 and 160.55
meters. The second rock (Breccia 2) is a polymict suevitic impact breccia (160.45-160.75 m) that contain shock
metamorphic features in quartz in the form of planar fractures (PFs) and planar deformation features (PDFs). The
third breccia (Breccia 3) is a polymict lithic impact breccia located between 160.75 and 161.4 meters. These breccias might have formed through slumping during the modification stage of impact crater formation, which means that
they would constitute crater fill, so called breccia lens material, or they might be part of the crater wall. If they are
part of the crater wall, the cataclastic breccia (Breccia 1) may have formed mostly in situ, during the compression
stage. The suevitic breccia (Breccia 2) could be some kind of intrusion-like sill, injected into fractures during the
excavation stage of impact crater formation, and the lithic breccia might have formed in a similar manner to the
suevitic breccia (Breccia 2). (Less)
Popular Abstract
Det är ett allmänt känt faktum att det som orsakade det senaste massutdöendet och
därmed slutet på dinosauriernas era var ett meteoritnedslag. Mindre känt är kanske det
faktum att meteoritnedslag faktiskt är ganska vanligt förekommande sett ur ett
geologiskt perspektiv. Lyckligtvis är konsekvensen av dessa väldigt sällan ett
massutdöende, men meteoriter kan ha en stor påverkan trots det. Ett exempel på detta är
en meteorit som slog ner för ca 470 miljoner år sedan. Alltså ca 237 miljoner år innan det
ens fanns dinosaurier. Denna bildade en krater som fått sitt namn efter den sjö den
befinner sig i, Hummeln. Hummelnkratern har tidigare undersökts med hjälp av
geofysiska metoder och en borrkärna har tagits upp och undersökts. Detta... (More)
Det är ett allmänt känt faktum att det som orsakade det senaste massutdöendet och
därmed slutet på dinosauriernas era var ett meteoritnedslag. Mindre känt är kanske det
faktum att meteoritnedslag faktiskt är ganska vanligt förekommande sett ur ett
geologiskt perspektiv. Lyckligtvis är konsekvensen av dessa väldigt sällan ett
massutdöende, men meteoriter kan ha en stor påverkan trots det. Ett exempel på detta är
en meteorit som slog ner för ca 470 miljoner år sedan. Alltså ca 237 miljoner år innan det
ens fanns dinosaurier. Denna bildade en krater som fått sitt namn efter den sjö den
befinner sig i, Hummeln. Hummelnkratern har tidigare undersökts med hjälp av
geofysiska metoder och en borrkärna har tagits upp och undersökts. Detta arbete går ut
på att klassificera och undersöka vissa av de bergarter som bildats vid nedslaget och som
finns i borrkärnan. Speciellt fokus ligger på de mer granitrika delarna närmst botten,
samt att diskutera bildningssett av dessa bergarter i mer
detalj. (Less)
Please use this url to cite or link to this publication:
author
Svensson, Ludvig LU
supervisor
organization
course
GEOL02 20241
year
type
M2 - Bachelor Degree
subject
keywords
Hummeln, the Hummeln structure, impact breccias, impactite classification, shock metamorphism, planar deformation features, impact craters, planar fractures, flow features, impact structures
publication/series
Dissertations in Geology at Lund University
report number
687
language
English
id
9163263
date added to LUP
2024-06-13 16:01:00
date last changed
2024-06-13 16:01:00
@misc{9163263,
  abstract     = {{The Hummeln structure is a relatively recently confirmed impact structure located in the northeastern
part of the province of Småland in Sweden (57.37347°N 16.25084°Ö). Due to its relatively recent confirmation,
detailed petrographic studies regarding shock metamorphism and shock metamorphic features in the Hummeln-1
drill core are lacking. The drill core is the only drill core from the structure and reached about ~164.25 meters,
measured from the lake surface. This study describes, classifies, and discusses three rock types from the lower part
of the drill core, and their relationship to the impact event. Three thin sections from these rock types were analysed
using polarizing microscopy, two of which were also analysed using scanning electron microscopy (SEM). From
the top down, the first rock (Breccia 1) is a monomict cataclastic impact breccia located between 159.14 and 160.55
meters. The second rock (Breccia 2) is a polymict suevitic impact breccia (160.45-160.75 m) that contain shock
metamorphic features in quartz in the form of planar fractures (PFs) and planar deformation features (PDFs). The
third breccia (Breccia 3) is a polymict lithic impact breccia located between 160.75 and 161.4 meters. These breccias might have formed through slumping during the modification stage of impact crater formation, which means that
they would constitute crater fill, so called breccia lens material, or they might be part of the crater wall. If they are
part of the crater wall, the cataclastic breccia (Breccia 1) may have formed mostly in situ, during the compression
stage. The suevitic breccia (Breccia 2) could be some kind of intrusion-like sill, injected into fractures during the
excavation stage of impact crater formation, and the lithic breccia might have formed in a similar manner to the
suevitic breccia (Breccia 2).}},
  author       = {{Svensson, Ludvig}},
  language     = {{eng}},
  note         = {{Student Paper}},
  series       = {{Dissertations in Geology at Lund University}},
  title        = {{Echoes of impact: A petrographic analysis and classification of impact breccias from Hummeln, Sweden.}},
  year         = {{2024}},
}