The origin and composition of flysch deposits as an attribute to the excessive erosion of the Slani Potok valley („Salty Creek“), Croatia

Scientific paper - Original scientific paper

• Author: Dunja Aljinović; MBZ: 139495
• Author: Vladimir Jurak; MBZ: 19163
• Author: Marta Mileusnić https://orcid.org/0000-0003-3776-3661; MBZ: 230876
• Author: Dragutin Slovenec; MBZ: 43733
• Author: Filip Presečki
• Author's institution: University of Zagreb; Faculty of Mining, Geology and Petroleum Engineering; (Department of Mineralogy, Petrology and Mineral Resources)
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Geology

Abstract (english)

Flysch deposits that crop out in the elongated coastal area of the Vinodol Valley (External Dinarides), and particularly in the Slani Potok (‘Salty Creek’) catchment, are characterized by excessive erosion. Formation of badlands, creeping and sliding processes have been related to crystallization of thenardite. Unusually intense erosion is caused by the dispersive effect of sodium on clay particles (derived from pelitic flysch intervals) in solution, as well as by expansion of thenardite during transformation into a deckahydrate (with a four fold increase in volume). The search for a sodium source required for thenardite crystallization has focused on a particular composition of Slani Potok Eocene fl ysch rock types. Slani Potok flysch is predominantly composed of pelitic intervals, with subordinate sandstones and biocalcirudites. Sandstones and biocalcirudites contain appreciable amounts of siliciclastic detritus. Lithic fragments are represented by volcanic rocks revealing porphyry structures - possibly andesite or altered volcanic glass fragments, quartzite, schists, shales, and carbonate grains. High amounts of sodium and barium (0.93–1.09 % and 267–276 mg/kg respectively), in marls and sandstones, is essentially ascribed to a particular composition of flysch, refl ecting its area of provenance. A Palaeozoic clastic complex with barite mineralization, (black shales, sandstones and conglomerates), as well as a Mesozoic hornblende andesite located near Fužinski Benkovac in the Gorski Kotar region, are interpreted as flysch source rocks. Sodium at least could be partly leached from the lithic and feldspar grains in clastic rocks, due to circulation of pore fluids. An increased amount of sulphur, barium and strontium in flysch can be related to that of a barite ore complex in the source area of the Gorski Kotar region. Transportation and deposition of material eroded from the hinterland (North of Slani Potok), suggests turbidity current flow was transverse to the main axis of the Eocene foreland basin striking NW-SE.

• Keywords (english): composition of flysch deposits; origin of flysch deposits; excessive erosion; Slani Potok; External Dinarides; Croatia
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: Geologia Croatica
• Numbering: vol. 63, no. 3, pp. 313-322
• p-ISSN: 1330-030X
• e-ISSN: 1333-4875
• DOI: https://doi.org/10.4154/GC.2010.25
• URN:NBN: urn:nbn:hr:169:381888
• Publication: 2010
• Document URL: https://hrcak.srce.hr/61003
• Type of resource: Text
• Access conditions: Open access
• Created on: 2019-11-27 10:00:09