Characteristics and origin of deformation structures within lignite seams – a case study from Polish opencast mines

Abstract

1 Adam Mickiewicz Uni ver sity, In sti tute of Ge ol ogy, Maków Polnych 16, 61-606 Poznañ, Po land Widera, M., 2016. Char ac ter is tics and or i gin of de for ma tion struc tures within lig nite seams-a case study from Pol ish opencast mines. Geo log i cal Quar terly, 60 (1): 181-191, doi: 10.7306/gq.1268 The pres ent pa per dis cusses the gen e sis of some de for ma tion struc tures within Mio cene lig nite seams in Po land. These meso-to macro-scale de for ma tion struc tures are the best de vel oped in ar eas where the thick est lig nite seams are ex ploited, that is, in the Be³chatów, Turów and Lubstów lig nite opencast mines. They show a wide va ri ety of struc tures such as high-angle in clined strata, nor mal and re verse faults and folds, frac tures and clastic dikes. These de for ma tion struc tures were not ana lysed in terms of the struc tural de vel op ment of the lig nite-bear ing ar eas, but rather in the con text of their or i gin. The high-an gle in cli na tion of clastic sed i men tary strata clearly formed mainly as a re sult of ver ti cal tec tonic move ments in the sub-Ce no zoic base ment, their cur rently mea sured dip an gle be ing sig nif i cantly higher than their nat u ral an gle of re pose. All the ob served nor mal and re verse faults cut ting the Mio cene strata are a clear ex am ple of syn-and/or post-depositional tec-ton ics. The nor mal faults clearly in di cate ten sional tec ton ics while the re verse faults re flect compressional tec ton ics. In turn, the ma jor ity of folds oc cur ring within the lig nite seams are a re sult of peat/lig nite com pac tion. How ever, one of the folds studied is pre dom i nantly the re sult of ver ti cal dis place ments in the sub-Ce no zoic base ment. The en ech e lon frac ture pat tern may ad di tion ally in di cate the hor i zon tal com po nent of these dis place ments. Fi nally, the most spec tac u lar and de bat able structures are clastic dikes. In this study the gen e sis of some of them is linked with the evo lu tion of the graben's mar ginal fault.

Early stages of clastic deposition in the Most Basin (Ohře Rift, Czech Republic, Early Miocene): timing and possible controls

“…In the Bílina delta area, peat compaction caused the stepwise progradation of clastic deposition (Dvořák & Mach 1999. The termination of peat compaction by the early stages of clastic deposition was also demonstrated in Polish coal mines by Widera (2016b). The assumption of a low net deposition rate during C5Dr in the Bílina Mine area is also supported by the fact that the overall thickness of the deposits of MZ0 in core HD50 is greater than that in LB297 (Fig.…”

Tectonic and Glaciotectonic Deformations in the Areas of Polish Lignite Deposits

“…The exploited lignite seams are of the early and middle Miocene age. They stratigraphically represent the third Ścinawa lignite seam (ŚLS-3), second Lusatian lignite seam (LLS-2), and first Mid-Polish lignite seam (MPLS-1) [11,[16][17][18][19]. Polish lignite deposits are likely the most genetically differentiated examples in the world.…”

“…Polish lignite deposits are likely the most genetically differentiated examples in the world. Their formation was influenced by geological factors including epeirogenic and tectonic movement, salt and carbonate karstification, erosion, compaction and glaciotectonics [3,9,16,18,19]. The majority of the exploited and extractable lignite deposits occur within grabens.…”

A method for the estimation of dual transmissivities from slug tests

“…Their displacements are caused by tectonic deformations of the basement, especially near the fault zones and the salt dome. Moreover, the exploitation of lignite involves relocating vast amounts of gangue to surrounding areas, which evokes tectonic activities in the region such as earthquakes, rock displacement and rock fracturing (Widera 2016).…”