The Himmerkinlahti member: An indicator of intra-karelian erosion within the early Proterozoic Kuusamo Belt, Posio, northern Finland

• Published in: Bulletin of the Geological Society of Finland
• Main Author: K. Laajoki
• Format: Article in Journal/Newspaper
• Language: English
• Published: Geological Society of Finland 2000
• Subjects: metasedimentary rocks; lithostratigraphy; sequence stratigraphy; erosion; Proterozoic; Karelian; Himmerkinlahti; Posio; Kuusamo; Finland; Geology; QE1-996.5; karelia*; karelian; Northern Finland
• Online Access: https://doi.org/10.17741/bgsf/72.1-2.005; https://doaj.org/article/050e846608e24ed5869a83dd37b8d3f2

The paper establishes the Himmerkinlahti Member, which is a thin metamorphosed conglomerate-sandstone unit within the middle part of the early Proterozoic (Karelian) supracrustal sequence of the Kuusamo Belt, northern Finland. Polymictic conglomerate beds with intra-Karelian supracrustal and (meta)diabase clasts and abundant hematite mineral clasts characterize the member. The latter represent intercumulus oxide phase of the (meta)diabases. The member also includes hematite-laminated lithic sandstone interbeds. The Himmerkinlahti Member is interpreted to represent a minor coarse-grained alluvial braid/braidplain delta and is evidence of a period of significant subaerial erosion during deposition of the early Proterozoic Karelian formations in northern Finland. Its rocks are likely part of a lowstand prograding wedge of type 1 sequence of the Kuusamo Belt.