Miner Petrol (2014) 108:187–206 DOI 10.1007/s00710-013-0295-1 ORIGINAL PAPER Using detrital garnets to determine provenance: a case study from the Vertiskos Unit (Serbomacedonian Massif, N. Greece) Ioannis K. Georgiadis & Antonios Koroneos & Lamprini Papadopoulou & Nikolaos Kantiranis & Alexios E. Tamparopoulos & Ananias Tsirambides Received: 2 February 2013 /Accepted: 20 May 2013 /Published online: 9 June 2013 # Springer-Verlag Wien 2013 Abstract Garnet single crystals of several millimeters in composition, tectonics, climate and relief; these factors diameter were collected from the uppermost horizon of a grouped together are referred to as provenance (e.g. soil profile developing immediately on the gneissic rocks of Dickinson 1970; Suttner 1974). In a more descriptive way, the Vertiskos Unit of the Serbomacedonian Massif in north- the provenance includes the paleogeography of a region, the ern Greece. The garnets were analyzed for major elements identification of possible source areas for the clastic material by EDS analyzer mounted on a scanning electron micro- under study and the revealing of details concerning the scope, and the obtained data were utilized to determine their paleocurrents and the paleoslope (Pettijohn et al. 1973). source rocks. Bivariate diagrams, spider diagrams as well as Especially Quaternary sediments are considered very useful statistical analysis were used in order to correlate and com- in provenance studies, because the effects of diagenetic pare the garnet composition of the basement rocks of the dissolution are minor compared to ancient sandstones Vertiskos Unit with the existing reference data. This case (Garzanti and Ando 2007). study demonstrates the difficulty in assigning a source rock According to Blatt et al. (1972), the accessory or heavy to sediment, using only the chemical compositional of de- minerals are extremely useful constituents of sediments with trital garnet. Direct linking of the detrital garnets and the regard to determining provenance despite rarely being pres- outcropping rocks is not always possible despite well doc- ent in amounts greater than 1 % of the clastic rock. Heavy umented outcrop lithologies. This is largely due to a com- minerals have long been used as indices of provenance, plex metamorphic evolution that leads to overlapping com- though the processes of transportation and the environment positions between garnets originating from different lithol- of deposition may alter the composition of the detrital frac- ogies that have undergone similar metamorphic processes tion. Pettijohn et al. (1973) consider iron-poor garnet as a and alteration effects. stable detrital heavy mineral and iron-rich garnet as a mod- erately stable one. Since garnet (a) is the most common heavy mineral in Introduction most siliciclastic sandstones, (b) is resistant to alteration under weathering and common diagenetic conditions and The factors that combine to produce detrital assemblages (c) has compositions that may reflect the compositions of found in modern and ancient sediments include source-rock the source rocks, it is commonly selected for provenance studies (Morton 1987; Di Giulio et al. 1999). Especially in podzol-type soil profiles, garnet is considered moderately Editorial handling: J. Kosler stable and is present under acidic conditions but not under * : : : I. K. Georgiadis: ( ) A. Koroneos L. Papadopoulou strongly alkaline (e.g. Morton and Hallsworth 1999). N. Kantiranis A. Tsirambides The garnet group is the most widely used provenance School of Geology, Department of Mineralogy-Petrology-Economic Geology, Aristotle University of Thessaloniki, 541 24 indicator in NW European sediments, due to its abundance Thessaloniki, Greece and its wide range of potential compositions (Morton et al. e-mail: [email protected] 2004). In general, detrital garnet is considered to mostly originate from metamorphic rocks (Blatt et al. 2006). A. E. Tamparopoulos Institute for Structural Engineering, University of Natural Resources Caution is advised though, since garnet assemblages may and Applied Life Sciences, 1190 Vienna, Austria demonstrate significant changes with age (Win et al. 2007). 188 I.K. Georgiadis et al. According to Morton et al. (2004), tracing garnet com- Geological setting positions directly back to their source rocks is more difficult than using them for discriminating sandstones of different The study area belongs to the Serbomacedonian Massif provenance; this is mainly due to the lack of a comprehen- (SMM) (Kockel and Walther 1965) and more specifically sive database on garnet compositions in basement rocks. comprises the Northern and major part of the Vertiskos Unit Therefore a multidisciplinary approach is advised (e.g. (Kockel et al. 1971, 1977), northern Greece. The SMM forms Morton and Hallsworth 1999; Win et al. 2007). a zone of rocks approximately 600 km long and 60–100 km Suggate and Hall (2013) have found that not all garnets wide, with N/NW (344o)-S/SE (132o) trend, in the central part can be definitely matched to a protolith; this issue espe- of the Balkan Peninsula. It is divided into three geomorphol- cially occurs when the source rocks are unknown, when ogic units, namely the Northern, the Central and the Southern compositional data from garnet-bearing rocks are not avail- (Psilovikos 1984). The Vertiskos (geotectonic) Unit studied able, or finally because the garnets have been removed by here coincides with the northern part of the Southern erosion. In these cases it is unclear whether compositional (geomorphologic) Unit of the SMM. It is an area of diverse data from other areas can be used to accurately determine relief, with mountain-horst and basin-graben structures provenance. (Psilovikos 1984). For the present work we utilized solely geochemical The maximum altitude of the Vertiskos Unit is approxi- compositional data acquired from detrital garnet pheno- mately 1,179 m and the Unit is drained from several rivers crysts, collected from a modern soil profile developing and torrents. This complex drainage system is generally of immediately on the basement rocks of the Vertiskos Unit dendritic pattern, discharging its detrital load to Gallikos and (Serbomacedonian Massif, N. Greece). It represents a case Strymon Rivers (west and east ends of the Massif, respec- study of determining the source rocks using only the chem- tively), to Doirani and Kerkini Lakes to the north and to ical composition of garnet. The problems that arose are Lagada and Volvi Lakes to the south (north and south ends documented and several methods for solving them are of the Unit, respectively), Fig. 1. The Unit generally has a employed. smooth relief, with smoothly sloping mountains and two Fig. 1 Petrographic sketch map of the study area according to IGME (1978a, b, c, 1979a, b, c, 1990) Using detrital garnets to determine provenance 189 extensive uplifted planation surfaces at 400–600 m and & Acid plutonic rocks. These rocks are generally known as 600–800 m (Psilovikos 1984). the Arnea Granite Suite (e.g. Dixon and Dimitriadis The Greek part of the SMM is divided into the upper 1987) and their age is Permian-Triassic (247–244 Ma, Vertiskos Unit and the lower Kerdillia Unit (Kockel et al. Poli et al. 2009). 1971, 1977). More recently, on the basis of lithological char- & Pegmatites. They are found as veins in the mica schists acteristics of the basement rocks, the SMM was further divid- and the amphibolites. Their age is Jurassic to Tertiary ed into several main Units, namely Pirgadikia, Vertiskos, (Marakis 1969; Zervas 1980). Arnea and Kerdillia (Himmerkus et al. 2007). The older & Small occurrences of Tertiary acid volcanic rocks. definition of Kockel et al. (1977) is used throughout this study. & Poorly sorted Tertiary massive graywackes along with The metamorphic basement of the Vertiskos Unit consists poorly sorted and massive arkoses (Chatzidimitriadis et of mainly Palaeozoic metasediments and metabasic rocks, al. 1993). along with Mesozoic granites. In general, the Unit has The principal rock types of the Vertiskos Unit are deformed undergone a metamorphosis during the Paleozoic to the orthogneisses, with their precursor rock being a medium- amphibolite facies, followed by a Cretaceous retrograde grained porphyritic biotite-granite, now preserved in strain- metamorphosis to the greenschist facies (Mountrakis free pockets in the orthogneisses (Himmerkus et al. 2009). 2002). In detail the Unit is composed of the following lith- The orthogneisses are associated with amphibolites and low- ologic types: grade metasediments, the latter present only at the western border of the SMM and at its central part (Himmerkus et al. & Gneisses (orthogneisses, garnetiferous migmatitic gneisses, 2007). To the West the meta-sediments are in tectonic contact mica schists, pelites, semi-pelites, meta-sandstones, meta- with the Circum Rhodope Belt, a low-grade metamorphic arkoses and marbles). These lithologies occupy the bulk of volcano-sedimentary succession (Kauffmann et al. 1976). the study area. Some marbles are rarely found as beds or Especially the meta-sediments of the western border of the lenses in schists, mainly with stratigraphic contacts. The SMM must have as protoliths potassic arkoses and gray- orthogneisses are considered to originally be volcanic-arc wackes of mixed provenance, igneous and sedimentary granites showing within-plate affinities, demonstrating an (Veranis et al. 1990). age of 490–405 Ma (Meinhold 2007). The meta-sediments Two garnet generations can be distinguished