Organic Compounds and Conditioning Films Within Deep Rock Fractures of the aspo Hard Rock Laboratory, Sweden

Abstract

Palaeoproterozoic grano-dioritic rocks of the island of aspo exhibit several mineralized fracture generations mainly filled by quartz, calcite, fluorite and/or epidote. Manganese-rich calcite fractures of probably Palaeozoic age are related to younger, possibly Pleistocene/Holocene cracks formed during the last ice age and successive crustal uplift, in contact to the host rock, which are sometimes associated with organic matter. Signals of organic molecules could be gained on the corresponding phase boundaries with Raman spectroscopy, likewise HPLC and HPAE-PAD reveal the presence of carbohydrates and amino acids in bulk rock samples. It is supposed that most of the preserved organic matter is related with thin conditioning films. Extracted bacterial and fungal DNA from the grano-dioritic rocks indicates still active microbial activity in fracture micro-niches.