ARTYKUŁY NAUKOWE Skały syderytowe jury środkowej Kujaw – studium petrologiczne
Abstract
The Middle Jurassic sideritic rocks of the Kujawy area – petrological study.
A b s t r a c t. The paper presents the results of new mineralogical and petrographic analyses of Middle Jurassic sideritic rocks in the Kujawy area. The scope of the research has been extended to the Ciechocinek–Brześć Kujawski–Wojszyce zone, where clayey and sandy siderites and sideritic coquina form only inserts in siliciclastic rocks. Early diagenetic sideroplesite and mesodiagenetic sideroplesite, Fe-dolomite, ankerite, pistomestite and calcite occur among carbonate minerals. They are accompanied by an early diagenetic green mineral called chamosite and identified as berthierine in the XRD analysis. The richest mineral composition occurs in the sideritic coquina containing various shell elements, often also ooids. It is suggested that the formation of the coquina in the Kłodawa–Łęczyca anticline area was caused by saline movements of the Cimmerian orogeny. The start-up and blending of salt masses and the rock fracture contributed to the intensive circulation of mineralizing solutions and the development of diagenetic processes, especially the replacement of unstable components and the cementation of Jurassic sediments throughout the Kujawy area.
A b s t r a c t. The paper presents the results of new mineralogical and petrographic analyses of Middle Jurassic sideritic rocks in the Kujawy area. The scope of the research has been extended to the Ciechocinek–Brześć Kujawski–Wojszyce zone, where clayey and sandy siderites and sideritic coquina form only inserts in siliciclastic rocks. Early diagenetic sideroplesite and mesodiagenetic sideroplesite, Fe-dolomite, ankerite, pistomestite and calcite occur among carbonate minerals. They are accompanied by an early diagenetic green mineral called chamosite and identified as berthierine in the XRD analysis. The richest mineral composition occurs in the sideritic coquina containing various shell elements, often also ooids. It is suggested that the formation of the coquina in the Kłodawa–Łęczyca anticline area was caused by saline movements of the Cimmerian orogeny. The start-up and blending of salt masses and the rock fracture contributed to the intensive circulation of mineralizing solutions and the development of diagenetic processes, especially the replacement of unstable components and the cementation of Jurassic sediments throughout the Kujawy area.