engleski

Possible changes of clastic detritus source in the Kloštar structure during Late Pannonian en Early Pontian

The Kloštar structure is hydrocarbon field in the Sava Depression, close to Moslavačka gora Mt. It is logical to consider influence of mountain as source of deposited inside Kloštar structure through 2nd transtension period. Mineral differences cannot be clearly observed in well cores taken from Late Pannonian and Early Pontian sandstones. There is only slight difference, indicating more mica minerals in Late Pannonian cores and harder compaction. It can be assumed that some sands detritus passed significantly shorter distance in Late Pannonian, and mica minerals had not been weathered in transport. It is possible only if part of sands and silts came from Moslavačka gora Mt., probably with short alluvial fans. Indicator Kriging maps clearly showed changing of depositional directions from Pannonian to Pontian. NW-SE direction in Late Pannonian was very well seen on probability maps, when turbiditic currents came from the westernmost part of the Sava Depression and continued mostly parallel with structurally determined shapes. But later, in the Early Pontian transport direction pattern is characterized with N-S strike. There is not enough proves that uplifted palaeorelief on the Sava Depression margins, through Pannonian and Pontian, had remarkable influences on quantity and mineral composition of detritus. For now it stay as probably assumption for the Kloštar structure and hypotheses for the entire depression. Such local detritus sources could be probably active on depression, tectonically active margins, where small alluvial fans existed.

Kloštar structure; Upper Pannonian; Lower Pontian; clastics source; Moslavačka gora Mt.; Eastern Alps

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