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

Abstract

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.

Keywords

• metasedimentary rocks
• lithostratigraphy
• sequence stratigraphy
• erosion
• Proterozoic
• Karelian
• Himmerkinlahti
• Posio
• Kuusamo
• Finland