Mesoproterozoic Frost Action at the Base of the Svinsaga Formation 291

NORWEGIAN JOURNAL OF GEOLOGY Mesoproterozoic frost action at the base of the Svinsaga Formation 291

Mesoproterozoic frost action at the base of the Svinsaga Formation, central Telemark, South Norway

Juha Köykkä & Kauko Laajoki

Köykkä, J. & Laajoki, K. 2009: Mesoproterozoic frost action ath the base of the Svinsaga Formation, central telemark, South Norway. Norwegain Journal of Geology, vol 89, pp 291-303. Trondheim 2009, ISSN 029-196X.

The Mesoproterozoic Svinsaga Formation (SF) in central Telemark, South Norway, was unconformably deposited after ca. 1.347 Ga on the quartz arenite of the upper member of the Brattefjell Formation (UB), which is part of the Vindeggen Group. The unconformity is marked by a fracture zone a few meters thick developed in the UB quartz arenite. The lower part of the fracture zone, which contains sparse and closed fractures, and microfractures, grades upwards into a system of wider and mostly random oriented fractures and fracture patterns. The fractures are filled with mudstone. The fracture zone is overlain by several meters of in situ SF breccia, in which the fragments consist solely of the UB quartz arenite. The in situ breccia gradually grades into a basal breccia and clast- or matrix-supported conglomerates. The SF conglomerate beds contain solitary quartz arenite fragments and blocks up to 9.0 m3 that were derived from the UB. The fractures, fracture patterns, and microfractures in the UB quartz arenite and shattered quartz arenite fragments in the in situ SF breccia are ascribed to in situ fracturing, brecciation, and the accumulation of slightly moved blocks in a cold climate. The characteristics of the fractures and fracture patterns indicate rapid freezing and volumetric expansion. Because the paleotopography is not known, the origin of the breccia zone cannot be reliably established, but it most likely represents an ancient debris-mantled slope or blockslope accumulation. Some of the fragments in the breccia zone are slightly rotated and tilted, probably due to periglacial frost-heaving and mass-wasting processes. Chemical solution features around quartz arenite clasts are attributed to cold-climate chemical weathering. Observations suggest that the contact zone between the UB and the SF was affected by cryogenic weathering in a periglacial environment during the Mesoproterozoic. The block accumulation affected sedimentation patterns of the overlying SF, which was deposited by later alluvial processes. This study supports the idea that the unconformities and associated deposits record valuable information about the paleoclimate and paleosedimentology of the time.

Juha Köykkä, Department of Geosciences, University of Oulu, P.O. BOX 3000, 90014 Oulu, Finland. Tel.: +358 8 5531439; Fax: +358 8 5531484. E-mail: [email protected] .

Introduction and releasing rock debris, which affects transports and deposition systems in the sedimentary basins (see Paleoweathering can provide valuable information Matsuoka & Murton, 2008). about the formation of the different rock units and the paleoclimatic conditions operative during their Descriptions of Mesoproterozoic (ca. 1.5 – 1.0 Ga) deposition. Thus, the frost weathering is a fundamental deposits ascribed to periglacial frost action or frost geomorphic process operating in periglacial shattering are rare in the geological literature. Williams environments. The term periglacial refers to the non- & Tonkin (1985) and Williams (1986) described the glacial processes, conditions, and landforms associated late Precambrian Cattle Grid breccia in South Australia, with cold climates (Ballantyne & Harris, 1994; French, within which frost shattering of quartzite bedrock 2007). In a periglacial environment, frost action has been produced an in situ breccia horizon interpreted to have used as a collective term to describe distinct processes formed through frost action under seasonal freeze- that result from alternate freezing and thawing cycles. thaw cycles during the Marinoan Glaciation, about Frost weathering is usually most active at some finite 635 – 600 Ma. The interpretation of periglacial in situ depth where the rate of cooling is sufficiently slow for brecciation of the quartzite is supported by the existence significant moisture to migrate to microfractures as of associated sand-wedge polygon and sand-wedge the freezing front advances (Hallet et al., 1991), and the structures, although these features are not necessarily rock fails when the shattering force exceeds the tensile unambiguous paleoenvironmental indicators (Murton strength of the rock. According to Hall (1988), Matsuoka et al., 2000). Mustard & Donaldson (1987) suggested (1991) and Ballantyne & Harris (1994), the breakdown that freeze-thaw action may have played an important mechanism depends on the thermal regime (amplitude of role in separating blocks in the upper part of a breccia freezing cycles and rate of freezing), moisture conditions in the Paleoproterozoic Gowganda Formation in (e.g., degree of rock saturation), and lithology (texture Canada. Young and Gostin (1988) interpreted the and chemistry). Frost weathering is most intense where thin Paleoproterozoic basal breccias at the base of the ground temperatures oscillate around 0o C, promoting Sturtian rocks in the North Flinders Basin, Australia, numerous freeze-thaw cycles, disintegrating of bedrock as periglacial. Laajoki (2002a) interpreted that the basal 292 J. Köykkä & K. Laajoki NORWEGIAN JOURNAL OF GEOLOGY brecciation at the Neoproterozoic unconformity around indicators survived and remained recognizable. However, Varangerfjorden, northern Norway, to have formed in a it is probable that Mesoproterozoic periglacial and periglacial environment by physical weathering. Laajoki glacigenic deposits were produced by processes similar (2002b) also described the Mesoproterozoic sub-Heddal to those observed in their younger, better preserved unconformity in Telemark, South Norway, and argued counterparts (cf. Eriksson et al., 1998; Eriksson et al., that the irregular geometry of individual fractures, the 2004; Donaldson et al., 2004). fracture framework in general, and associated in situ mosaic breccias indicate that break-up of the quartz This study describes and interprets the unique, slightly arenite substratum was caused by surficial processes metamorphosed and deformed basal fracture and breccia such as freeze-thaw. A glacigenic interpretation was also zones at the base of the Mesoproterozoic SF, central suggested for the fragmentation of the basement gneiss of Telemark, South Norway. The base of the SF is defined a Neoproterozoic roche moutonnée feature at Karlebotn, by the Sub-Svinsaga unconformity (SSU), which was first Finnmark (Laajoki, 2003). recognized by Dons (1960a, 1960b), but has only recently been defined formally (Laajoki et al., 2002). The rarity of descriptions and reports of Mesoproterozoic periglacial frost action deposits is not surprising, since deposits of that age have usually been affected by diverse Geological setting tectonic and metamorphic processes and later weathering and erosion. This can make certain recognition of any The study area belongs to the Mesoproterozoic (ca. 1.5 typical periglacial or cold climate indicators like sand – 1.0 Ga) sedimentary-volcanic Telemark supracrustal wedges, frost-shattered blocks, or frost fractures difficult belt or sequence (Sigmond et al., 1997), which occupies or even impossible. Only in some rare cases, have these the northern part of the Sveconorwegian Telemark

Fig. 1. Simplified lithostratigraphical and structural map of the southern part of the Telemark supracrustals, where the bedrock is subdivided into diverse structural domains by several faults (thick lines). The study area is framed. SSU = Sub-Svinsaga unconformity. MUFS = Mandal – Ustaos shear and fault zone. MF = Marigrønutan fault zone. NORWEGIAN JOURNAL OF GEOLOGY Mesoproterozoic frost action at the base of the Svinsaga Formation 293 sector (Bingen et al., 2005) or Telemark block (Andersen, 2005) of the Southwest Scandinavian Domain (Gaál & Gorbatschev, 1987) in the Fennoscandian (Baltic) Shield (Fig. 1). In contrast to most of the metamorphic Precambrian crust in South Norway, the Telemark supracrustal units are relatively well preserved (Dons, 1960a; 1960b; Laajoki et al., 2002; Bingen et al., 2003, 2005). They form a supracrustal sequence approximately 10 km thick, metamorphosed under low-grade greenschist-amphi-bolite facies conditions (Brewer & Atkin, 1987; Atkin & Brewer, 1990).

The SSU is the most important unconformity within the Telemark supracrustal rocks, and separates the sequence into two major packages: (1) the Vestfjorddalen Supergroup (Rjukan and Vindeggen Groups), deposited between ca. 1.51 – 1.347 Ga, and (2) the upper succession of Sveconorwegian units, deposited between ca. 1.169 – 1.019 Ga. The Vestfjorddalen Supergroup starts with the Rjukan Group, which contains continental felsic volcanics of the Tuddal Formation (ca. 1.51 Ga) and the volcanic-sedimentary Vemork Formation (ca. 1.495 Ga, Laajoki & Corfu, 2007; Corfu & Laajoki, 2008). The Rjukan Group is overlain by the Vindeggen Group, which is dominated by sedimentary rocks deposited between ca. 1.495 – 1.347 Ga (Corfu & Laajoki, 2008) in a continental rift setting (Lamminen & Köykkä, submitted and references therein). The Rjukan and Vindeggen Groups were folded before deposition of the volcanic-sedimentary Oftefjell Group, which in the study area consists only of the SF and a small body of the Ofte Formation porphyre that has been separated tectonically from the main body to the south (Fig. 1). The Sveconorwegian units are laterally restricted Fig. 2. Simplified geological map of the study area. Areas of Figs. 3A and variable, suggesting deposition in separate basins & 3B are framed. SSU = Sub-Svinsaga unconformity. (Laajoki et al., 2002, Andersen et al., 2004), possibly in a transtensional tectonic regime (Lamminen et al., 2009b).

The SSU and the basal parts of the SF above the UB quartz arenites, which form the topmost unit of the Vindeggen Group, are best exposed on the eastern flank of Svafjell Mountain and in the smaller hills of Meien and Sjånuten (Fig. 2). Deep erosion, which started after In Svafjell and Meien, the SF defines the western flank ca. 1.347 Ga (Corfu & Laajoki, 2008), produced the SSU and the NE hinge of the steeply plunging Meien syncline, on the folded Vindeggen Group. The isotopic dating and is cut by the Marigrønutan fault (Figs. 2, 3A & B). In indicates that at least a 200 Ma hiatus is associated with Sjånuten, the SF defines a north-west trending syncline this unconformity (Lamminen et al., 2009, Lamminen & cut by a fault near Lake Meisetjørn (Fig. 3B). Köykkä, submitted). In the following, we first briefly describe the In the type area of the SF, about 20 km south of the lithostratigraphy and then provide detailed descriptions study area, the SSU forms a clearly mappable angular and interpretations of the fracture zone developed in unconformity (Dons, 1960a, 1960b, 2003), but in the the UB and the overlying breccia zone of the lowermost study area, bedding positions in the UB and SF are so SF. Although all rocks in the study area have been similar that these formations appear to be conformable. metamorphosed in low-grade greenschist- to lower- This paper describes a major unconformity that occurs amphibolite-facies conditions, for simplicity the meta- between the UB and the SF. It should be noted, however, prefix is not used in lithological names. The sandstone that the three-dimensional geometry of the unconformity nomenclature used here is based on relative percentages itself cannot be defined precisely, because it does not of the major detrital components (Folk, 1980; Pettijohn form any larger surface and is visible only sporadically. et al., 1987). 294 J. Köykkä & K. Laajoki NORWEGIAN JOURNAL OF GEOLOGY

Figs. 3A & B. Geological maps and cross sections of the Svafjell, Meien and Sjånuten study areas (modified from Köykkä, 2006). Figure and outcrop numbers are given. SSU = Sub- Svinsaga unconformity. A) The SF is seemingly conformable with the bedding of the underlying UB. The SF defines the western flank of the Meien syncline. B) The SF in Meien defines the hinge and eastern flank of the Mein syncline cut by the Marigrønuten fault. In the Sjånuten area it occupies a north- west directed syncline or minor synclinorium bounded by a fault near the Lake Meisetjørn.

Lithostratigraphy Svafjell-Meien area

Based on distinctive facies assemblages, the Brattefjell In the Svafjell area, the first sign of the SSU between Formation is subdivided into lower, middle, and upper the UB and SF is a 1 – 3 m thick zone of mostly random (UB) members (Köykkä & Lamminen, in prep.). The oriented, closed or mudstone-filled fractures developed horizontal- and parallel-laminated UB quartz arenite in the uppermost part of the UB quartz arenite (Fig. 4A). forms the depositional basement for the SF (Fig. 2). Dons The fracture zone grades upward into an in situ breccia, (2003) mapped the major southern part of the SF starting where the blocks, matrixed by scanty mudstone, are solely with the Oftefjell Group in Fig. 1, whereas Köykkä of the UB quartz arenite. The fractures and in situ breccia (2006) described the lithologies and sedimentology of zone represent a weathering crust developed on the UB the SF in the Svafjell – Meien and Sjånuten areas, which quartz arenite, and define the SSU. The in situ breccia are separated tectonically from the southern part of the grades upward into a basal breccia, where the fragments SF. This paper concentrates on the northern area. In of cobble and block size have been moved or rotated this paper, the term “fragment” refers to a fragment of slightly. a sedimentary breccia, the size being less than that of a boulder (<256 mm), and a “block” refers to an angular On the western flank of the Meien syncline, the basal boulder-sized fragment (>256 mm). breccia is overlain by a matrix- and clast-supported SF conglomerate containing distinct fragments and blocks up to four meters long that have been transported from NORWEGIAN JOURNAL OF GEOLOGY Mesoproterozoic frost action at the base of the Svinsaga Formation 295 the UB quartz arenite (Fig. 4A). Upwards, well-rounded organized in texture. The quartz arenite clasts in the quartz arenite clasts derived from more distal sources diamictite unit are well-rounded to angular. The overlying become increasingly dominant, although solitary blocks horizontally laminated subarkose with occasional thin (1 of the UB up to half a meter long may occur among them. – 5 cm) mudstone interbeds forms a unit about 80 – 90 In the Meien area, the basal breccias and the SF subarkose m thick (Fig. 4A). The uppermost part of the SF (ca. 70 are overlain by a muddy diamictite unit about 30 m thick, m) consists of large-scale trough cross-bedded subarkose interpreted to have been deposited by subaerial debris with channel lag and some polymictic conglomerate beds flows and hyperconcentrated flow processes (Köykkä, (Fig. 4A). Paleoflow measurements of the trough cross- 2006) (Fig. 4A). The diamictite beds with erosional bases bedded sets and imbricated conglomerates indicate a are muddy, poorly sorted, and chaotic or only slightly unimodal southwest transport direction (Fig. 4A).

Figs. 4A & B. A) Stra- tigraphic summary column of the SF in the Svafjell-Meien area. See framed box for the facies codes (modified Miall, 2006) and legend. The UB quartz arenite fragments in the SF conglomerate and subarkose beds are marked by “UB”. Paleoflow measurements from the trough cross-bedded sets and imbricated conglomerates indicate a southwest transport direction. B) Stratigraphic summary column of the SF in the Sjånuten area. See framed box for the facies codes (modified after Miall, 2006) and legend. 296 J. Köykkä & K. Laajoki NORWEGIAN JOURNAL OF GEOLOGY

Sjånuten area zone (Fig. 6A) Upwards, the fractures become wider and The SF in the Sjånuten area (Fig. 3B) starts with an in their margins are usually smooth or partly corroded. situ breccia developed on the UB quartz arenite (Fig. 4B). The fragments and boulders in the breccia are derived The only outcrop where a larger surface parallel to the solely from the UB quartz arenite, with a matrix of bedding plane of the topmost part of the UB can be scanty mudstone. This breccia zone is a couple of meters seen is in Meien. There, the fractures are up to 15 cm thick and is overlain by about 18 m thick massive, clast- wide and are filled by mudstone with occasional quartz supported, polymict conglomerates that contain solitary arenite pebbles (Fig. 6B). This view represents a unique blocks of the UB quartz arenite up to four meters long section viewed across the top part of the fracture zone (Fig. 4B). The volume of the fracture blocks varies from and parallel to the SSU. The fracture zone grades upwards 1.0 m3 to 9.0 m3 or more. In other places, the breccia is into the basal breccia zone, where a fracture network and missing and the clast-supported boulder conglomerate, in situ breccia are developed oblique to the bedding in the made up solely of UB blocks, lies directly on the UB (Fig. UB quartz arenite. 5A). Interpretation The facies associations, coarseness of the basal conglomerates and the presence of the large UB blocks Fractures and fracture patterns can be produced in indicate that the SF in the Sjånuten area represents the bedrock by several different mechanisms, including most proximal area of the SF. This is supported by the tectonic, hydrothermal, unloading, and different southwest paleoflow direction in the SF (Fig. 4A). weathering processes (solution, insolation, and frost action). It is important to consider all these potential mechanisms when interpreting ancient fracture systems. Fracture zone The possible effects of these different mechanisms on the UB quartz arenite are considered below. Description A tectonic fracture system can be produced in bedrock The following description of the fracture zone on the by compressive, tensile, or shearing stress and is rarely eastern flank of Svafjell represents a vertical traverse randomly oriented. Thus, one or several dominant of the original section and is given from the base of the orientations typically develop and basic fracture sets can zone upwards. The UB quartz arenite immediately under usually be identified by statistical methods (Scheidegger, the unconformity does not have any features indicating 2001). Using a parametric statistic, Kohlbeck and significant deformation before the deposition of the SF. Scheidegger (1977) determined that 21 measurements of The only structural feature in the UB quartz arenite and fracture orientations in an outcrop should be sufficient the Sub-Svinsaga paleosurface is a widely spaced fracture to determine the stress field (if any) that produced the framework perpendicular to the bedding (Fig. 5B). Some fractures. Sampling of fracture orientations can be biased of the fractures are a few millimeters wide and are filled by the geometry or scale of the sampling domain, which with mudstone. This zone, which is a few meters thick, means that fractures that are subparallel to bedding are represents the deepest part of the surficial fracture less likely to be sampled than those at higher angles. system generated in the UB quartz arenite when it was However, this kind of bias error can be corrected using uplifted to the erosion level. It grades upwards into a the method described by Terzaghi (1965), which is based zone where the mudstone-filled fractures are wider (Figs. on a trigonometric correction factor and an assumption 5B – D). The bottom part of the fracture zone begins that the fracture spacing in different sets is fairly equal. with fractures ranging from a few millimeters up to five The fracture measurements carried out using the method centimeters wide, and from a few centimeters up to one of Kohlbeck and Scheidegger (1977) from the fracture meter long. They were originally filled by clay and/or silt, zone in the UB quartz arenite included 70 directional which is now metamorphosed into purple sericite-rich and dip measurements (Fig. 5E). These indicate that mudstone. The contact margins between the UB quartz the major fracture system in the UB quartz arenite is arenite and the SF mudstone fill are partly corroded, mostly random oriented (Fig. 5E), and that it is unlikely and the mudstone may replace the silica cement of the that it was produced by a tectonic process. Some of the quartz arenite over a distance of a few millimeters. These fractures, for instance those that are vertical or parallel to mudstone-filled fractures are the first distinctive hint of bedding, may be pre-existing cracks or fractures, or may the SSU (Fig. 3A). Some of the fractures are subparallel be related to some inherent structural weakness. to bedding in the UB, but most of them are randomly oriented (Figs. 5C & 5E). Many of the lowermost It is possible that at least some of the fractures were fractures are rectilinear with sharp margins, possibly formed or at least widened by unloading of a hypothetical representing previous fractures or other pre-existing pre-Svinsaga ice overburden after the vertical compressive structural weaknesses in the quartz arenite, but curved stress was relieved. The opening of pre-existing fractures fractures are also common (Fig. 5C). Microfracturing is in response to unloading is important in the case where also a common feature in the bottom part of the fracture water can reach into widened cracks and intensify the NORWEGIAN JOURNAL OF GEOLOGY Mesoproterozoic frost action at the base of the Svinsaga Formation 297 weathering process. However, the glacial unloading Frost weathering has been traditionally attributed to process is often masked by the patterns of existing stresses caused by the expansion of water during freezing structural weaknesses in the rock, making it difficult to in fractures, joints, or bedding planes (macrogelivation) recognize its effects in an ancient rock record, especially or within microcracks and pores (microgelivation). where no convincing indicators of an ice sheet exist. The bedrock frost-shattering process in a periglacial environment can be subdivided into three major Provided that a sufficient amount of moisture and water mechanisms (McGreevy, 1981; French, 2007): (1) is available, dissolution weathering of a quartz arenite hydrofracturing, (2) ice segregation, and (3) thermal can lead to fracture patterns similar to those found in shock. Each distinct frost shattering mechanism is carbonate rocks. The dissolution removal of silica under important in different periglacial conditions, and usually earth-surface conditions is a significant process, even several mechanisms act together in breaking down the in sub-polar latitudes (Wray, 1997a, 1997b). Solution rock. in quartz arenites begins from fractures or other easily penetrated zones within the rock and continues along (1) Hydrofracturing is the volumetric expansion of water crystal boundaries (Fjellanger & Nystuen, 2007), and upon freezing, where the water penetrates rock fractures tends to produce rounded features around the fractures. and pores and expands about 9% on freezing; the stress This is in contrast to the UB quartz arenite, where the caused by the expansion tends to break the rock apart. fractures are mostly rectilinear and sharp and form This process is favored by wet conditions, rapid cooling, a network with acute angles (Figs. 5C & D). Thus, and frequent freeze-thaw cycles (Matsuoka, 1990). we conclude that dissolution has not been a major Because the fractures in the upper part of the fracture mechanism forming the fractures and fracture patterns zone were open before the deposition of the SF, they in the UB quartz arenite. provided access for water flow and hydrofracturing of

Figs. 5A – E. Photographs of the SSU and fracture zone. A) Boulder conglomerates deposited directly on the UB quartz arenite. The SSU marked by stick (1.6 m long). B) Close-up of the open fracture zone. Scale bar is 5 cm. The white arrow points to a fracture approximately parallel to the bedding in the UB. C) A basal view of the in situ breccia fragments with irregular fracture network. Stick is 1.6 m long. D) Close-up of the open fracture zone showing a network of mostly randomly orientated fractures. Note that some of the wider fractures have been particularly filled by angular in situ quartz arenite detritus enclosed and infiltrated by infiltrated mudstone (arrow) E) Seventy fracture orientation measurements from the UB quartz arenite in Svafjell area, presen- ted in a Schmidt equal area stereonet. Contour lines and intervals represent the point densities, which indicate that some of the fracture patterns are randomly orientated, but some of them may represent pre-existing fractures or some other structural weaknesses. The three different eigenvalues provide direct information about the distribution and uniformity of the data set, and indicate that distribution is not entirely uniform. 298 J. Köykkä & K. Laajoki NORWEGIAN JOURNAL OF GEOLOGY the UB quartz arenite. The randomly oriented fracture of the breccia zone. The blocks and fragments consist pattern in the UB quartz arenite supports rapid freezing solely of UB quartz arenite. They show no evidence of and volumetric expansion, which tend to produce a any preferred orientation of tectonic origin. Some of the mostly random oriented fracture pattern (Mackay, 1999). quartz arenite fragments have been broken in situ and are filled by purple mudstone (Fig. 6C). The interfragmental (2) Ice segregation is attributed to freezing in a water- matrix spaces widen upwards and occasionally the matrix saturated rock. It is analogous to slow freezing in consists of mudstone with quartz arenite clasts (Fig. fine-grained soils. The expansion is the result of 6D). The margins of the fragments and blocks are either water migration to growing ice lenses and secondly to sharp, rounded (Fig. 6E), or partly corroded (Fig. 6F). volumetric expansion (Hallet et al., 1991). In this process, The well-defined weathering pits typical of slow chemical frost shattering of a rock results from the progressive dissolution weathering were not found in the UB quartz expansion of micro-cracks and pores. According to arenite fragments or blocks. Murton et al. (2001), the ice segregation mechanism usually forms a dominant alignment of cracks parallel The quartz arenite in the fragments and blocks in the or sub-parallel to the cooling surfaces (ground surface breccia zone is lithologically identical to that of the or bedrock), because ice lenses usually form parallel underlying UB, as demonstrated by the red color caused to the isotherms. The mostly random orientation of by diagenetic hematite, the mature blastoclastic arenitic the fractures in the UB quartz arenite suggests that ice texture with well-rounded quartz grains and minor segregation might not have been the dominant frost silica cement, the mineralogical supermaturity, and weathering process in the study area. Murton et al. (2001) sedimentary structures. The grain size varies between noted, however, that variable orientations of cracks due 0.125 – 0.250 mm. The characteristic feature of the to ice segregation probably reflect variable water content quartz grains is a partly sutured texture where the grain as a result of non-uniform wetting. The pre-existing edges are irregular due to compaction or weak tectonic fractures in non-porous rock are more vulnerable to action. In addition, overgrowth and relic edges due to volumetric expansion associated with rapid freezing than pressure solution are observed in some of the grains. The to ice segregation. composition of the mudstone fill between the breccia fragments and blocks varies from quartz- to sericite-rich (3) Thermal shock, i.e., insolation weathering, is the with variable amounts of muscovite, feldspar, quartz, and fracturing of bedrock due to temperature-induced iron oxide. The sericite-rich variety is more common. The volume changes (expansion and contraction). It requires mudstone matrix is slightly metamorphosed, containing that the bedrock experiences temperature contrasts occasional randomly oriented chloritoid porphyroblasts. and has capillary size pores (French, 2007). The thermal shock mechanism tends to form fracture patterns that Interpretation show a remarkable angularity of junctions (often at almost 90o to each other) and a relative hierarchy of The SF breccia zone above the UB indicates an abrupt cracks, where the small cracks are at right angles to the change in depositional system. Unfortunately, the sub-SF major ones (Hall & Andre, 2001; Hall et al., 2002). The paleoslope is not exposed in three dimensions. The fact fracture patterns typical of this mechanism are not found that the SF fragments are not rotated, or are rotated in the UB quartz arenite. Consequently, it is unlikely only slightly, indicates that the breccia material was not that the thermal shock mechanism caused the intensive transported any long distance. This excludes solifluction, granular disintegration actually observed in the fracture avalanching, rockfall on a talus slope, and debris flows zone of the study area. as significant processes in explanation of its origin. Consequently, the packing of the SF fragments and blocks more likely favors block accumulation, like a blockfield, Breccia zone blockslope, or a debris-mantled slope where the breccia fragments at the surface are firmly embedded in the Description matrix grains.

In the Svafjell and Sjånuten areas, the SF breccia zone In the SF breccia zone, in situ fracturing of the bedrock starts with the blocks, which are either in situ or have was the most important process, and periglacial processes been rotated or moved only slightly. The blocks have a (e.g., mass-wasting, frost-heaving) may have controlled scanty matrix of purple mudstone. The lower part of the the distribution of the fragments and blocks. In periglacial SF breccia zone is tightly packed and the rock fragments environments, mass-wasting processes can be subdivided are mostly large blocks, but their size and sorting decrease into (1) the gradual downslope displacement of slope stratigraphically upwards. The orientation of the long sediments due to repeated freezing and thawing, and (2) axis of the blocks is more systematic in the middle part more localized rapid slope failures that occur sporadically of the breccia zone, where most blocks have their long during thaw of the active layer or underlying permafrost axes parallel to the bedding of the UB. However, the (Ballantyne & Harris, 1994). The former results from long-axis orientation is more variable in the upper parts the combined effect of frost creep and gelifluction, for NORWEGIAN JOURNAL OF GEOLOGY Mesoproterozoic frost action at the base of the Svinsaga Formation 299 which the term solifluction is often used (op. cit.). The The in situ or slightly displaced fragments and blocks slightly rotated fragments and blocks in the upper part in the SF breccia zone, like in many blockfields of the SF breccia zone indicate frost-heaving, since larger and blockslopes, developed during cold climate fragment and block angles with respect to the horizontal conditions where freeze and thaw processes operate bedding plane would represent gravitational solifluction (cf. Boelhouwers, 1999a, 1999b; Steijn et al., 2002). It is or some other mass wasting process. In the gravitational well known that criteria like block accumulation or clast mass wasting process (gelifluction), the longitudinal shape alone are not sufficient as paleoenvironmental axial planes of fragments tend to be in the downslope indicators. Thus, the paleoenvironmental significance of direction, producing a slight uphill imbrication and dip autochthonous blockfields depends on the interpretation parallel to the ground surface, or at an angle less than the of the origin of the fragments and blocks, which is usually slope angle (e.g., Hétu et al., 1995; Van Steijn et al., 1995; attributed to in situ frost-shattering of bedrock under Perez, 1998). The rotation and tilting of the SF breccia cold conditions (Steijn et al., 2002). Clast angularity, the fragment and block axes resulted from differential frost absence of grussification, and a transition to underlying heave at the top and bottom parts of the fragments and rock, which exist in the lower part of the SF breccia zone, blocks, and all particles were subjected to rotation during imply formation by in situ frost- shattering of the bedrock the heave phase. In general, the heaving is controlled by (Ballantyne, 1998). The freeze-thaw depth controls the the air temperature, moisture supply, depth and rate of maximum dimension of the detachable rock mass, while freezing, snow conditions, and freeze-thaw cycles. The fracture spacing determines the size distribution of heaving also requires either confined conditions or the the rockfall debris (Matsuoka & Sakai, 1999). Thus, the presence of finer material (Dredge, 2000), suggesting that maximum size of the largest SF blocks indicates that the the SF breccia fragments and blocks did not have an open freeze-thaw depth in the UB paleo-weathering surface framework at the time of heaving. was 1 – 4 m.

Figs. 6A – F. Photographs of the fractures and breccia fragments. A) Tightly packed bottom part of the fracture system with minor mudstone fill and narrow fractures. Notice the microfractures (marked with arrows). Scale 15 cm. B) Wider fractures in an UB quartz arenite filled by pebbly mudstone. View is vertical to the bedding plane of the UB quartz arenite. Scale 15 cm. C) In situ fragmented quartz arenite clasts interpreted to be caused by ancient frost action and repeated freeze- thaw cycles. Mudstone fills the fractures (arrows). Compass base is 12 cm long. D) The interfragment space filled by mudstone with UB quartz arenite clasts .E) Pillow like breccia fragments with mudstone-filled fractures. The rounded, but irregular and open form of the fragments indicates chemical solution of the quartz or/and melt water action. Compass 12 cm long. F) Chemical solution features (arrows) around quartz arenite clasts. Compass 12 cm long. 300 J. Köykkä & K. Laajoki NORWEGIAN JOURNAL OF GEOLOGY

The solitary UB quartz arenite fragments and blocks in sedimentation, and different periglacial processes (e.g. the upper parts of the SF subarkose (Fig. 4A) may indicate bedrock frost-weathering, frost-heaving, mass-wasting, minor ploughing, avalanching, or solifluction processes. blockfield and/or rock slope accumulations) (Fig. 7). In These processes require the blockslope angular gradient the late stage (syn/post-faulting) of the basin evolution, to be 8o – 30o in order to be active in a periglacial the newly formed geomorphic features were adjusted environment (Ballantyne & Harris, 1994; French, 2007). by the sediment transport systems. The sedimentation This suggests that the SF fragments and blocks did not included alluvial incision on the fractured bedrock, accumulate on a completely flat surface. However, the lacustrine and/or marine deposition, and possible assumption of the slope angle is more complex, and can volcanism (Fig. 7). A possible continuation of frost vary greatly in different parts of the slope and change weathering at a later stage is an open question, as there over time on an evolving slope. Usually, blockfields and is no direct evidence of this during the sedimentation. blockslopes have complex structures comprising different However, minor frost-weathering would have been likely slope dips, and as a consequence, varying degrees of snow during sedimentation of the SF. and debris cover (Gruber, 2004).

The corroded quartz arenite clasts and pillow-like breccia Discussion cobbles and boulders in the SF breccia zone indicate in situ chemical solution and weathering (Figs. 6E & F). Indicators of paleoweathering and periglacial processes Some corroded quartz grains visible in thin sections in the Precambrian bedrock can be difficult to recognize. support this interpretation, as does the geochemical CIA- The fact that these indicators are often masked and index (75 – 78) from mudstone samples (Köykkä, 2006). covered by other sedimentary and structural features may Chemical weathering is not restricted to humid tropical lead to misinterpretation of the depositional processes areas, but can also act in periglacial environments, even and even paleoclimate. The recognition of cold-climate to the same extent as physical weathering (Anderson periglacial features from Precambrian deposits should be et al., 1997; Wray, 1997; Allen et al., 2000; Dixon & based on an assemblage of indicators and detailed facies Thorn, 2004). Johnson et al. (1970) and Robert & analysis (see Eriksson et al, 1998, Eriksson et al, 2004). Reynolds (1971) also mention that low mean annual Laajoki (2002b) described a fracture zone a few meters air temperatures in a periglacial environment do not thick in the Sub-Heddal unconformity in Telemark, necessarily limit chemical weathering processes, since South Norway, with irregular fracture features, mosaic- melt water runoff can be chemically corrosive when it is like breccia, and irregular paleochannels excavated continuously recharged with CO2. Several other authors into the UB quartz arenite. He noticed that the fracture (Sharp et al., 1995; Wadham et al., 1998; Hodson et al., framework in the UB quartz arenite starts with thin 2000) have also noted chemical erosion by snow or fractures subparallel to bedding, and that their number, glacial melt water. According to Sharp et al. (1995), the width, and curvature increase stratigraphically upwards. efficacy of meltwaters in chemical weathering can be The lower part of the fracture zone in the Sub-Heddal attributed to high flushing rates, turbulent flow, high unconformity contains boulder-size fragments that are suspended sediment concentrations, and low buffering partly attached to their sub-stratum, and fractures up to capacity of dilute melt waters. It is possible that the 10 cm wide containing pelitic material. Laajoki (op. cit.) rounded pillow-like cobbles and boulders in the SF reflect concluded that the Sub-Heddal unconformity represents later, pre-Pleistocene, deep chemical weathering by a deep paleoerosional feature, and the break-up and corrosive melt water. However, due to the lack of suitable paleochannel carving of the UB quartz arenite may geochronological methods, it is impossible to determine suggest surficial processes like freeze-thaw combined when this chemical weathering took place. with solution weathering.

Although the Sub-Heddal unconformity (ca. 1.155 Paleosedimentology – 1.145 Ga) cannot be correlated definitely with the SSU or any other unconformity within the Telemark The SF facies associations and sedimentary structures supracrustal units, when taken together with the present (large-scale trough cross-bedding, alluvial conglomerates, study, it suggests that the Telemark supracrustals may channel lag etc) indicate that the SF represents an alluvial have experienced significant frost-weathering during sedimentation system in a strike-slip (pull-apart) basin Mesoproterozoic time. (Köykkä, 2006; Köykkä, in prep.). This suggests that the overlying SF conglomerate and subarkose beds (Fig. 4) have been deposited over the blockfield or rock slope Conclusions by later alluvial processes, while part of the sedimentary material worked its way into the fractures between The irregular features of the fractures, fracture patterns, the fragments and the blocks. In the early stage of the microfractures, shattered UB quartz arenite clasts, and basin evolution (pre/syn-faulting), the rapid subsidence mudstone fill indicate that periglacial alteration pro- was associated with lacustrine and possible marine cesses played an important role in the genesis of the pre- NORWEGIAN JOURNAL OF GEOLOGY Mesoproterozoic frost action at the base of the Svinsaga Formation 301

Fig. 7. A schematic paleosedimento- logical figure of the strike-slip basin evolution and sedimentation of the SF and associated units (modified from Einsele, 2000). The pre/syn- faulting stage was characterized by different periglacial processes (frost- weathering, mass- wasting, frost- heaving etc.) and possible lacustrine and/or marine sedimentation. The extensional faulting stage was fol- lowed by alluvial incision and the SF sedimentation over block field or block slope. Figure not to scale.

SF fracture system associated with the SSU. This indi- and nature of the breccia fragments and blocks support cates cryogenic weathering in a periglacial environment formation by block accumulation, in cold climate con- with a “combination of mechanico-chemical processes ditions with operative freeze-thaw processes combined which cause the in situ breakdown of rock under cold- with minor block ploughing and solifluction. The overly- climate conditions” (French, 1996; French, 2007). The ing SF conglomerate and subarkose beds were deposited characteristics of the fracture zone indicate rapid freez- over the block accumulation by later alluvial processes ing and volumetric expansion. In the study area, the role and worked their way down into the spaces between the of frost-shattering is also supported by the fracture zone fragments and blocks. In the early stage of basin evolu- passing upwards into the in situ breccia zone, and then to tion (pre/syn-faulting), rapid subsidence was associated a debris-mantled block or blockslope accumulation with with different sedimentation processes and bedrock UB fragments and blocks. frost-weathering, frost- heaving, mass-wasting, and blockfield and/or rock slope accumulations. In the late Although reliable structural evidence concerning the stage (syn/post faulting) of the basin evolution, the newly ancient paleoslope under the SF is missing, it is evi- formed geomorphic features were modified by allu- dent that in situ weathering was an essential process in vial incision of the fractured bedrock, lacustrine and/or the supply of breccia fragments and blocks. The sorting marine deposition, and possible volcanism. 302 J. Köykkä & K. Laajoki NORWEGIAN JOURNAL OF GEOLOGY

Acknowledgements. Dons J.A. 1960a: Telemark supracrustals and associated rocks. The study is based on the first author’s unpublished M.Sc. thesis (2006) In: Holtedahl O. (Ed.), Geology of Norway. Norges Geologiske available at the University of Oulu. The paper is a contribution to the Undersøkelse, 49 – 58. Research Projects Nos. 207099 & 207346 of the Academy of Finland. Dons J.A. 1960b: The stratigraphy of supracrustal rocks, granitization The authors would like to thank Dr. B. Bingen and an anonymous and tectonics in the Precambrian Telemark area, Southern Norway. reviewer for constructive comments on the manuscript. Dr. J. Murton Norges Geologiske Undersøkelse, Vol. 212h, 1 – 30. made numerous suggestions that were helpful during writing an early Dons J.A., Heim M., Sigmond, E.M.O. 2004: Berggrundskart Frøystaul version of this manuscript. 1514 II, M 1:50 000. Norges Geologiske Undersøkelse Dredge L.A. 2000: Age and origin of upland block fields on Melville Peninsula, Eastern Canadian Arctic. Journal of Geografiska Annaler, Vol. 82 A, 443 – 454. References Einsele G. 2000: Sedimentary basins: evolution, facies, and sediment budget (2nd ed.). Springer-Verlag Berlin, Heidlerberg New York, Allen C.E., Darmody R.G., Thorn C.E., Dixon J.C., Schlyter P. 2000: 792. Clay mineralogy, chemical weathering and landscape evolution in Eriksson P.G., Condie K.C., Tirsgaard W.U., Mueller W.U, Altermann Arctic – Alpine Sweden. Geoderma, Vol. 99, Issue 3 – 4, 277 – 294. W., Miall A.D., Aspler L.B., Catuneanu O., Chiarenzelli J.R. 1998: Andersen T. 2005: Terrane analysis, regional nomenclature and Precambrian clastic sedimentation system. Sedimentary Geology, crustal evolution in the southwest Scandinavian domain of the Vol. 120, 5 – 53. Fennoscandian Shield. GFF 127, 159 – 168. Eriksson P.G., Bumby A.J., Popa M. 2004: Sedimentation through Andersen, T., Laajoki, K., Saeed, A. 2004: Age, provenance and time. In: The Precambrian earth: Tempos and events (Ed.: Eriksson tectonostratigraphic status of the Mesoproterozoic Blefjell P.G., Altermann W., Nelson D.R., Mueller W.U. and Catuneaunu quartzite, Telemark sector, southern Norway. Precambrian Research O.). Developments in Precambrian Geology, Vol. 12, 593 – 602. 135, 217 – 244. Fjellanger J. & Nystuen P.N. 2007: Diagenesis and weathering of Anderson S.P., Drever J.I., Humphrey N.F. 1997: Chemical weathering quartzite at the palaeic surface on the Varanger Peninsula, northern in glacial environments. Geology, Vol. 25, Issue 5, 399 – 402. Norway. Norwegian Journal of Geology, Vol. 87, pp. 133 – 135. Atkin B.P., Brewer T.S. 1990: The tectonic setting of basaltic Folk, R. L. 1980: Petrology of sedimentary rocks. Austin: Texas magmatism in the Kongsberg, Bamble and Telemark sectors, Hemphill’s Book Store, 190 pp. Southern Norway. In: Mid-Proterozoic Laurentia-Baltica (Ed.: French H.M. 1996: The periglacial environment (2nd Edition). Gower C.F., Rivers T., Ryan B.). Special paper – Geological Addison Wesley Longman Limited, 335 pp. Association of Canada, Vol. 38, 471 – 483. French H.M. 2007: The periglacial environment (3rd Edition). Ballantyne C.K. 1998: Age and significance of mountain-top detritus. Addison Wesley Longman Limited, 458 pp. Permafrost and Periglacial Processes, Vol. 9, 327 – 345. Gaál, G., Gorbatschev, R. 1987: An outline of the Precambrian Ballantyne C.K., Harris C. 1994: The periglaciation of Great Britain. evolution of the Baltic Shield. Precambrian Research, Vol. 35, 15 – Cambridge University Press. 325 pp. 52. Bingen B., Birkeland A., Nordgulen Ø. and Sigmond E.M.O., Tucker Gruber S., Hoelzle M., Harberli W. 2004: Rock-wall temperatures in R.D., Mansfeld J., Höghdahl K. 2003: Relations between 1.19 – 1.13 the Alps: Modelling their topographic distribution and regional Ga continental magmatism, sedimentation and metamorphism, differences. Permafrost and Periglacial Processes, Vol. 15, 299 – 307. Sveconorwegian province, South Norway. Precambrian Research, Hall K. & Andre M-F. 2001: New insights into rock weathering from Vol. 124, 215 – 241. high-frequency rock temperature data: An Antarctic study of Bingen B., Skår Ø., Marker M., Sigmond E.M.O., Nordgulen Ø., weathering by thermal stress. Geomorphology, Vol. 41, 23 – 35. Ragnhildstveit J., Mansfeld J., Tucker R.D., Liegeois J.-P. 2005: Hall K., Thorn C. E., Matsuoka N., Prick A. 2002: Weathering in Timing of continental building in the Sveconorwegian orogen, cold regions: some thoughts and perspectives. Progress in Physical southwest Scandinavia. Norwegian Journal of Geology, Vol. 85, 97 Geography, Vol. 26, Issue 4, 577 – 603. – 166. Hallet B., Walder J.S., Stubbs C.W. 1991: Weathering by segregation Boelhouwers J. 1999a: Block deposits in southern Africa and their ice growth in microcracks at sustained subzero temperatures: significance to periglacial autochthonous blockfield development. Verification from an experimental study using acoustic emissions. Polar Geography, Vol. 23, 12 – 22. Permafrost and Periglacial Processes, Vol. 2, 283 – 300. Boelhouwers J. 1999b: Relic periglacial slope deposits in the Hex River Hétu B., Steijn van H., Bertran P. 1995: Le rôle des coulées de pierres Mountains, South Africa: Observations and paleoenvironmental sèches dans la genèse d’un certain type d’éboulis stratifiés. implications. Geomorphology, Vol. 30, 245 – 258. Permafrost and Periglacial Processes, Vol. 6, 173 – 194. Brewer T.S., Atkin B.P. 1987: Geochemical and tectonic evolution of Hodson A., Tranter M., Vatne G. 2000: Contemporary rates of the Proterozoic Telemark supracrustals, southern Norway. In: chemical denudation and atmospheric CO2 sequestration in Geochemistry and mineralization of Proterozoic volcanic suites glacier basins: An Arctic perspective. Earth Surface Processes and (Ed.: Pharaoh T.C., Beckinsale R.D., Rickard D.T.). Geological Landforms, Vol. 25, 1447 – 1471. Society Special Publications, Vol. 33, 471 – 487. Johnson N.M., Reynolds R.C., Cambell W. 1970: Rate of chemical Corfu F. & Laajoki K. 2008: An uncommon episode of mafic weathering in a temperate glacial environment. The Annual magmatism at 1347 Ma in the Mesoproterozoic Telemark Meeting of the Geological Society of America, 1970, 588 pp. supracrustals, Sveconorwegian orogen – Implications for strati- Kohlbeck F., Scheidegger A.E. 1977: On the theory of the evaluation of graphy and tectonic evolution. Precambrian Research, Vol. 160, pp. fracture orientation measurements. Rock Mechanics, Vol. 9, Issue 299-307. 1, 9 – 25. Dixon John C., Thorn Colin E. 2004: Chemical weathering and Köykkä J. 2006: Mesoproterotsooisen Svinsagan muodostuman landscape development in mid-latitude Alpine environments. sedimentologia, Telemark, Etelä-Norja (in Finnish). Unpublished Geomorphology, Vol. 67, Issue 1 – 2, 127 – 145. M.Sc. Thesis, University of Oulu, Department of Geosciences, pp. Donaldson J.A., Aspler L.B., Chirenzelli J.R. 2004: An essential key for 126. interpreting the Precambrian rock record. In: The Precambrian Köykkä J., Laajoki K. 2006: The Mesoproterozoic Svinsaga Formation, earth: Tempos and events (Ed.: Eriksson P.G., Altermann W., central Telemark, South Norway: Sedimentological researches Nelson D.R., Mueller W.U. and Catuneauny O.). Developments in and paleocurrent analysis indicate periglaciofluvial braided river Precambrian Geology, Vol. 12, 602 – 612 depositonal environment affected by talus breccia input. The 27th NORWEGIAN JOURNAL OF GEOLOGY Mesoproterozoic frost action at the base of the Svinsaga Formation 303

Nordic Geological Winter Meeting, Abstract Volume, Bulletin of Sharp Martin, Tranter Martyn, Brown Giles H., Skidmore Mark 1995: the Geological Society of Finland, Special Issue I, 82 pp. Rates of chemical denudation and CO2 drawdown in a glacier- Köykkä J. & Lamminen J. in prep.: Mesoproterozoic tidal covered alpine catchment. Geology, Vol. 23. no. 1, 61 – 64. sedimentation system in a stable basin conditions: transgression Scheidegger A.E. 2001: Surface fracture systems, tectonic stresses from lagoonal estuary to nearshore setting, Telemark, South and geomorphology: a reconciliation of conflicting observations. Norway. Geomorphology, Vol. 38, 213 – 219. Laajoki K. 2002a: New evidence of glacial abrasion of the late Sigmond E.M.O., Gjelle S., Solli A. 1997: The Rjukan Proterozoic rift Proterozoic unconformity around Varangerfjorden, Northern basin, its basement and cover, volcanic and sedimentary infill, and Norway. In: Spec. Publ int. Ass. Sediment. Nr. 33 (Ed.: Altermann associated intrusions. Norges Geologiske Undersøkelse Bulletin, Vol. W. & Corcoran P.L.), 405 – 436. 433, 6 – 7. Laajoki K. 2002b: The Mesoproterozoic sub-Heddal unconformity, Steijn van H., Bertan P., Francou B., Hétu B., Texier J.-P. 1995: Models Sauland, Telemark, South Norway. Norsk Geologisk Tidskrift, Vol. for the genetic and environmental interpretation of stratified slope 82, 139 – 152. deposits. Permafrost and Periglacial Processes, Vol. 6, 125 – 146. Laajoki K. 2003: The Larajæg´gi outcrop – a large combined Steijn van H., Boelhouwers J., Harris S., Hétu B. 2002: Recent research Neoproterozoic/Pleistocene roche moutonnée at Karlebotn, on the nature, origin and climate relations of blocky and stratified Finnmark, North Norway. Norwegian Journal of Geology, Vol. 84, slope deposits. Progress in Physical Geography, Vol. 26, Issue 4, 551 107 – 115. – 575. Laajoki K., Corfu F., Andersen T. 2002: Lithostratigraphy and U-Pb Terzaghi R. 1965: Sources of error in fracture surveys. Geotechnique, geochronology of the Telemark supracrustals in the Bandak- Vol. 15, 287 – 304. Sauland area, Telemark, South Norway. Norsk Geologisk Tidsskrift, Wadham J.L., Hodson A.J., Tranter M., Dowdeswell J.A. 1998: The Vol. 82, 119 – 138. hydrochemistry of meltwaters draining a polythermal-based, high Laajoki, K. & Corfu, F. 2007: Lithostratigraphy of the Mesoproterozoic Arctic glacier, south Svalbard: I. The ablation Season. Hydrological Vemork Formation, central Telemark, Norway. Bulletin of the Processes, Vol. 12, 1825 – 1849. Geological Society of Finland, 79, 41-67 Williams G.E. 1986: Precambrian permafrost horizons as indicators of Lamminen, J. & Köykkä, J. submitted: Provenance characteristics palaeoclimate. Precambrian Research, Vol. 32, 233 – 242. of the Mesoproterozoic Rjukan Rift Basin (Vindeggen Group), Williams G.E., Tonkin D.G. 1985: Periglacial structures and Telemark, South Norway: implications for the paleotectonic history palaeoclimate significance of a late Precambrian block in the Cattle of SW Norway. Precambrian Research. Grid copper mine, Mount Gunson, South Australia. Australian Lamminen, J., Köykkä, J., Andersen, T., Nystuen, J.P. 2009: From Journal of Earth Sciences, Vol. 32, 287 – 300. extension to transtension: the Telemark supracrustals, ca. 400 Wray R.A.L. 1997a: A global review of solutional weathering forms Ma sedimentary record variable tectonics before and during the on quartz sandstones. Earth-Science Reviews, Vol. 42, Issue 3, 137 Sveconorwegian (Grenvillian) Orogeny. AGU Joint Assembly 2009 – 160. (Abstract). Wray R.A.L. 1997b: Quartzite dissolution: karst or pseudokarst? Cave Mackey J.R. 1999: Cold-climate shattering (1974 – 1993) of 200 glacial and Karst Science, Vol. 24, 81 – 86. erratics on the exposed bottom of a recently drained arctic lake, Young G.M., Gostin V.A. 1988: Stratigraphy and sedimentology of western Arctic Coast, Canada. Permafrost and Periglacial Processes, Stuartian glacigenic deposits in the western part of the North Vol. 10, 125 – 136. Flinders Basin, South Australia. Precambrian Research, Vol. 39, 151 Matsuoka N. 1990: Mechanisms of rock breakdown by frost action: An – 170. experimental approach. Cold Regions Science and Technology, Vol. 17, 253 – 270. Matsuoka N., Sakai H. 1999: Rockfall activity from an alpine cliff during thawing periods. Geomorphology, Vol. 28, 309 – 328. Matsuoka N., Murton J.B., 2008: Frost weathering: recent advances and future directions. Permafrost and Periglacial Processes, Vol. 19, 195 – 210. McGreevy J.P. 1981: Some perspectives on frost shattering. Progress in Physical Geography, Vol. 5, 56 – 76. Miall A. 2006: The geology of fluvial deposits: Sedimentary facies, basin analysis, and petroleum geology. Springer (Corr. 3rd printing), 582 pp. Murton J.B., Worsley P., Gozdzik Jan 2000: Sand veins and wedges in cold aeolian environments. Quaternary Science Reviews, Vol. 19, 899 – 922. Murton J.P., Coutard J.-P., Lautridou J.-P., Ozouf J.-C., Robinson D.A., Williams R.B.G. 2001: Physical modeling of bedrock brecciation by ice segregation in permafrost. Permafrost and Periglacial Processes, Vol. 12, 255 – 266. Mustard P.S., Donaldson J.A. 1987: Substrate quarrying and subglacial till deposition by an early Proterozoic ice sheet: Evidence from the Gowganda Formation at Cobalt, Ontario, Canada. Precambrian Research, Vol. 34, 347 – 368. Perez F.L., 1998: Talus fabric, clast morphology, and botanical indicators of slope processes on the chaos grags (California Cascades), U.S.A. Geographie Physique et Quaternaire, Vol. 52, 1 – 22. Pettijohn, F., Potter, P., Siever, R. 1987: Sand and sandstone. Springer- Verlag, New York, 533 pp. Robert C., Reynolds Jr. 1971: Clay mineral Formation in an Alpine environment. Clays and Clay Minerals, Vol. 19, 361 – 374.