Pet Ro Logic Stud Ies and Diagenetic His Tory of Coaly

Annales Societatis Geologorum Poloniae (2011), vol. 81: 173–183. PETRO LOG IC STUDIES AND DIAGENETIC HISTORY OF COALY MATTER IN THE PODHALE FLYSCH SEDI MENTS, SOUTH ERN POLAND Mar ian WAG NER AGH Uni ver sity of Sci ence and Technol ogy, Fac ulty of Ge ol ogy, Geo phys ics and En vi ron men tal Pro tec tion, Al. Mickiewicza 30, 30-059 Kraków, Poland, e-mail:wagner@ge ol.agh.edu.pl Wagner, M., 2011. Pet ro logic stud ies of diagenetic his tory of coaly mat ter in the Podhale Flysch sed i ments, south ern Po land. Annales Societatis Geologorum Poloniae, 81: 173–183. Ab stract: Common occur rences of terrigenic or ganic mat ter (both dis semi nated and ac cu mulated in lay ers) in sed i mentary rocks were ob served. The flysch sed i ments in the Podhale Trough and in other parts of the Carpathians are in ad e quately re cog nised from coal pet ro logic point of view. Studies were car ried out in the east ern (2008) and west ern part (2009) of the Podhale Trough. Sam ples were col lected from the ex po sures. Petrographic stud ies in cluded mi cro scopic ob ser va tions of pol ished sec tions as well as mean random reflectance mea surements of vitrinite (colotellinite) were done. In the Podhale Flysch, coalified or ganic mat ter is rep re sented mostly by vitrinite and, in mi cro scopic scale, mainly by collotellinite. The com mon oc currence of coaly mat ter is revealed. It is well–visi ble in sandstones and mudstones, usually as the bed ding planes. The amounts of coaly mat ter in clay miner als and car bon ates are small. Organic mat ter hosted in the Podhale Flysch strata rep resents diver si fied coalification ranks mea sured as ran dom reflectance of vitrinite (colotellinite), which falls into the range from 0.49 to 1.00%. Such val ues are typ i cal for low- to me dium ranks of bi tu minous coal. Mea sure ments of reflectance pro vided new data suit able for eval u a tion of ther mal history of rocks in the Podhale Trough. The changes of vitrinite (colotellinite) mean reflectance of organic matter from the Podhale Flysch are rele vant to the contents of crys talline illite – the recently applied geothermometer of diagenetic (katagenetic) transfor ma tions of clay miner als. If the thermal palaeogra- dient is known, ran dom changes of reflectance of vitrinite can be used for es ti mations of both the max i mum thick ness of the Podhale Flysch dur ing de po sition and its later amount of ero sion. It ap pears that esti mation of ma- x i mum thickness of the Podhale Flysch (i.e., depositional thick ness af ter com pac tion) and the amount of ero sion are al most identi cal with the esti mations based upon the illitization of clay miner als. Key words: terrigenic or ganic mat ter, ran dom reflectance of vitrininite, the Podhale Flysch, Po land. Manu script re ceived 8 June 2011, ac cepted 3 November 2011 INTRODUCTION Com mon occur rence of terrigenic or ganic matter (both The flysch sedi m ents in the Podhale Trough and in dis sem i nated and ac cu mu lated in lay ers) in sed i men tary other parts of the Carpathians, although suffi cie ntly re cog- rocks to gether with the de velop ment of mod ern, fast petro- nised from the geo logi cal point of view, reveal many con - graphic methods of coalification rank measure m ents result trover sie s and uncertaintities concern ing their geotectonic in wide appli cati on of such petrographic obser va ti ons and po siti on. Studies of vitrinite coalification provide new in- mea sure ments in var i ous re search pro jects, e.g. of geotecto- ter pre ta tive op por tu ni ties, hence, rocks from the East ern nic his tory of par tic u lar re gions. and West ern Carpathians, from the Tatra Mts., from the In the Podhale Flysch sed im ents, coalified organic mat- Pieniny Klippen Belt and from the Podhale Trough are re- ter is rep re sented mostly by vitrinite. Mea sure ments of vitri- cently in ten sively in ves ti gated. The lat ter de pos its are par - nite mean reflectance (Ro) en able the sci en tists to solve many ticu larly useful due to suggest ed low degree of their tec - tec tonic problem s in both the orogenic belts and the plat- tonic trans for ma tion (de spite their sig nif i cant thick ness – forms as this pa ram e ter car ries in for ma tion on coalification several thousands of metres) and the posi ti on betwee n the as a functi on of sedi m ent burial within the Earth crust, coeval two young- Alpine orogens: the Pieniny Klippen Belt and with depo siti on and with later orogenic ac tiv ity. the Tatra Mts. 174 M. WAGNER Fig. 1. Geo log i cal sketch map of the Podhale Trough with lithostra tig ra phy of the Podhale Palaeogene Flysch and gen eral cross-sec tion (A – A ) through the Podhale Trough (af ter Cho- waniec, 1989; Chowaniec & Kêpiñska, 2003. In: Krobicki & Go- lonka, 2008; slightly modi fied) Fig. 3. Lithostratigraphic col umn of the Podhale Flysch in the impor tant parts of the Podhale Trough (af ter Geld, 2000, also Krobicki & Golonka, 2008, modi fied) In the northwest ern part of the Podhale region. i.e., in the Orawa porti on of the Nowy Targ–Orawa Trough a part Fig. 2. Lithostratigraphic cross sec tion (A – A, Fig. 1) of the of the Podhale Flysch succes sion is uncon form ably covered west ern part of the Podhale Trough (af ter Gedl, 2000. In: Krobicki by the Neogene (Miocene -Plio cene) intramontane mo las - & Golonka, 2008). PKB – Pieniny Klippen Belt ses. This suite com prises huge allu vial fans, several hun - dreds of metres thick (maxi m um thickness – 1,300 m), which have been de pos ited since the Early Mio cene, af ter the upli ft of the Tatra Mas sif and the folding of the Podhale Even the pre lim i nary re sults re veal com pli cated diage- Flysch. Their char ac ter istic feature is the pres ence of coaly netic his tory of the Podhale Flysch refle cted in sig nifi cant matter (Ko³con & Wagner, 1991). dif fer ences in coalification of con tained or ganic matter. The Podhale Flysch in cludes four lithostratigraphic units (Gedl, 2000; Ry³ko, 2004): the Szaflary beds, the Za- kopane beds, the Chocho³ów beds and the Ostrysz beds. GEO LOG I CAL SET TING The old est unit – the Szaflary beds (Fig. 3) – occurs in OF THE PODHALE FLYSCH the northern part of the Podhale Trough but it is ab sent from the southern part, at the con tact with the Eocene limestone s. The Palaeogene sedi m ents of the Podhale Trough are These are mostly sandstone s in the lower part (about 300 m divided into two lithostratigraphic units. The older unit thick), sand stones and shales (about 200 m thick) or sandsto- comprises shal low-ma rine car bon ates tra di tion ally named nes and conglom erate s in the upper part with the dom inance ”the Num mu litic Eocene”. It is fol lowed by the youn ger, of mudstones and claystones over sandstone s (Fig. 4). The flysch unit named ”the Podhale Flysch” (see, e.g., Watycha, sandstone s are fine-grained and thin-bed ded (0.1–3.0 m). In 1959; Mastella, 1975). the upper part of the succes sion, among claystones, the si lici- The imm e di ate base ment of the Podhale Flysch con sists fied shales of menilite type oc cur. of Eocene car bon ates which are in tec tonic con tact with the Both the con glom erate s and the sand stones of the High–Tatric and Sub-Tatric serie s, and which form the Szaflary beds contai n limestone grains derive d from the northern margin of the Tatra Mts. (Fig. 1, 2). Pieniny Klippen Belt whereas the flysch strata in clude full The Eocene carbon ates of total thickness about 150 m tur bid ity se quences iden ti fied as prox i mal flysch. Com mon are ex posed only along the northern margin of the Tatra com po nent of the Szaflary beds is plant detri tus and even a Mts. whereas the youn ger, Oligocene flysch strata, which few-centim etres-thick coal layers. fill the Podhale Trough crop out at num erous sites betwee n Scarce foraminifers iden tified in the Szaflary beds point the Tatra Mts. and the Pieniny Klippen Belt. out to Late Eocene age, but dinocysts observe d in the youn - COALY MAT TER IN THE PODHALE FLYSCH 175 Fig. 4. Sedimentological fea tures of the Podhale Flysch. A – Thin-bed ded Szaflary beds (Nowe Bystre vil lage); B – Folded Szaflary beds in the con tact zone with the Pieniny Klippen Belt (Szaflary vil lage); C – Lower Chocho³ów beds in the Bia³y Dunajec River (near Bia³y Dunajec vil lage); D – Break-thrust of Brzegi beds (Jurgów vil lage); E – Thin-bed ded Up per Chocho³ów beds (Kojsówka vil lage); F – black shales of Zakopane beds (Zakopane-Olcza vil lage) 176 M.

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