Lumparn Bay: A Meteorite Impact Crater in the Aland Archipelago, Southwest Finland
Abstract
Lumparn Bay, centered at latitude 60 degrees O9 minutes N and longitude 20 degrees 06 minutes E has a diameter of 10 km. The bedrock in the area is a rapakivi granite. Shatter cones have been found along the southwestern shore line of the bay. Drill cores do exist from the central part of the structure. Below Pleistocene sediments the topmost part of the bedrock is a Paleozoic limestone. It is followed downward by layers of crushed rapakivi granite that are very fine grained close to the limestone. The grain size increases systematically outward. If a fine-grained layer is designated "a" and the following layer, which has a larger grain-size, is designated "b," then the legend can be described as a(sub)n < b(sub)n where a(sub)1 < a(sub)2 ... a(sub)n and b(sub)1 < b(sub)2 < ... b(sub)n. It is suggested that this phenomenon might be characteristic for impact craters. In the uppermost part of the crushed rock material glassy patches do occur.
- Publication:
-
Meteoritics
- Pub Date:
- July 1993
- Bibcode:
- 1993Metic..28S.445S
- Keywords:
-
- FINLAND;
- GLASSES;
- IMPACT CRATERS;
- SHATTER CONES;
- SHOCK;
- TUMPARN