cryogenic carbonates in cave environments a review abstract cryogenic cave carbonate ccc represents a specific type of speleothem its precipitation proceeds at the freezing point and is triggered by freezing induced concentration of solutes compared to classical speleothems stalagmites flowstones ccc occurs as accumulations of loose uncemented aggregates the grain sizes range from less than 1 m to over 1 cm in diameter karst groundwater chemistry and its freezing rate upon entering the cave are responsible for highly variable grain morphology rapid freezing of water results in the formation of ccc powders with grain size typically below 50 m slow freezing of water in caves usually in systems where the co2 escape is partly restricted e g ice covered water pools results in the formation of large mineral grains with sizes from less than 1 mm to about 20 mm the range of carbon and oxygen stable isotope compositions of ccc is larger than for a typical carbonate speleothem rapid freezing of water accompanied by a quick kinetic co2 degassing results in large ranges of 13c of the ccc powders between 10 and 18 pdb slow freezing of water with a restricted co2 escape results in gradual increase of 13c values from 9 to 6 pdb data ranges in individual caves are usually much more restricted accompanied by a 18o decrease of the precipitated carbonate overall range from 10 to 24 pdb these unusual trends of the carbonate 18o evolution reflect incorporation of the heavier 18o isotope into the formed ice new isotope data on ccc from three romanian ice caves allow better understanding of the carbon and oxygen isotope fingerprint in carbonates precipitated from freezing of bulk water cccs are proposed as a new genetic group of speleothems

a geochemical comparison of the dalradian leven schists and the grampian division monadhliath schists of scotland suites of samples from the type area of the leven schist and from localities within the monadhliath schists of the central highlands have been analysed for major and trace elements and for their sr isotopes petrologically the two schist groups are consistently different the leven schists are muscovite rich plagioclase poor semipelites to pelites whereas the monadhliath schists are a typical moinian semipelite consisting almost entirely of biotite sodic andesine and quartz equally consistent geochemical differences between the two include more nb zr y and rb and less ca sr and ni in the leven than the monadhliath schists ratios of rb sr and of y to p 2 o 5 sr and cao discriminate the leven from the monadhliath schists factor analyses of the chemical data also serve to distinguish the two suites rb sr isochron studies give 655 f2 5ma initial 87 sr 86 sr 0 7232 f10 for the leven schists and 486 9ma initial sr 87 sr 86 0 7190 1 for the monadhliath schists and also separate the two formations from one another the 655 ma age for the leven schists is thought to record sedimentation and diagenesis whereas the 486 9 age for the monadhliath schists is probably related to the cessation of rb and sr migration at or after the peak of the grampian orogeny their sr isotopic compositions were also completely different hack to 1300 ma ago and serve to confirm the lack of any continuity between the leven and monadhliath schists sets of schists located between the main outcrop areas were also analysed and can be assigned without ambiguity either to the leven or the monadhliath schists on the basis of their chemistry the results of this study imply that the lower dalradian appin group rests on the grampian division unconformably and that the latter is closely related through its geochemistry to the moinian nw of the great glen

cryogenic cave calcite from several central european caves age carbon and oxygen isotopes and a genetic model abstract cryogenic cave calcite ccc formed by segregation of solutes during water freezing was found in three central european caves this calcite type forms accumulations of loose calcite grains on cave floor the calcite grains are of highly variable crystal morphology and of sizes ranging from less than 1 mm to over 1 cm the most typical feature is their accumulation as loose uncemented crystals u series dating indicates the formation of ccc in the studied caves during several climatic oscillations of the weichselian between 61 and 36 ka bp in the chelsiowa jama jaskinia jaworznicka cave system in poland between 34 and 26 ka bp in the buml cave in the czech republic and between 26 and 21 ka bp in the stratenska jasky a cave system slovakia at the time of ccc formation the studied caves were lying in a periglacial zone detailed c and o stable isotope study of ccc samples revealed that slow water freezing under isotope equilibrium was the dominant formational process in the studied polish and czech caves significantly higher 13 c values of ccc in the stratenska jasky a cave indicate either water freezing in a more opened system with continuous co 2 escape rayleigh fractional separation or participation of another co 2 source the model of slow water freezing under isotope equilibrium is supported by isolated character of the caves having limited ventilation in contrast modern cryogenic cave calcite powders sampled directly on the ice surface of two recently iced caves in slovakia with high ventilation showed much higher 18 o and 13 c data similar to cryogenic calcites obtained in experimental rapid water freezing

antarctic dry valleys microclimate zonation variable geomorphic processes and implications for assessing climate change on mars the antarctic dry valleys adv are generally classified as a hyper arid cold polar desert the region has long been considered an important terrestrial analog for mars because of its generally cold and dry climate and because it contains a suite of landforms at macro meso and microscales that closely resemble those occurring on the martian surface the extreme hyperaridity of both mars and the adv has focused attention on the importance of salts and brines on soil development phase transitions from liquid water to water ice and ultimately on process geomorphology and landscape evolution at a range of scales on both planets the adv can be subdivided into three microclimate zones a coastal thaw zone an inland mixed zone and a stable upland zone zones are defined on the basis of summertime measurements of atmospheric temperature soil moisture and relative humidity subtle variations in these climate parameters result in considerable differences in the distribution and morphology of 1 macroscale features e g slopes and gullies 2 mesoscale features e g polygons including ice wedge sand wedge and sublimation type polygons as well as viscous flow features including solifluction lobes gelifluction lobes and debris covered glaciers and 3 microscale features e g rock weathering processes features including salt weathering wind erosion and surface pitting equilibrium landforms are those features that formed in balance with environmental conditions within fixed microclimate zones some equilibrium landforms such as sublimation polygons indicate the presence of extensive near surface ice identification of similar landforms on mars may also provide a basis for detecting the location of shallow ice landforms that today appear in disequilibrium with local microclimate conditions in the adv signify past and or ongoing shifts in climate zonation understanding these shifts is assisting in the documentation of the climate record for the adv a similar type of landform analysis can be applied to the surface of mars where analogous microclimates and equilibrium landforms occur 1 in a variety of local environments 2 in different latitudinal bands and 3 in units of different ages documenting the nature and evolution of the adv microclimate zones and their associated geomorphic processes is helping to provide a quantitative framework for assessing the evolution of climate on mars

physicochemical and biological controls on carbon and nitrogen in permafrost from an ultraxerous environment mcmurdo dry valleys of antarctica little is known about the abundance and source of soil organic carbon and biogeochemical cycling in permafrost soils from the ultraxerous environment of the dry valleys of antarctica here we investigate the distribution source and cycling of organic carbon total nitrogen and carbonates in the icy permafrost soils of university valley quartermain mountains results indicate that organic carbon content is lowest in icy soils from the perennially cryotic zone 40 g g 1 dry soils and higher in the icy soils from the seasonally non cryotic zone where the highest concentrations were found in the warmer wetter section of the valley and near a frozen pond up to 313 g g 1 dry soils the 13corg of organic carbon in the icy soils showed that it is derived from the weathering of beacon supergroup sandstone that hosts active endolithic communities the c n ratios in icy soils formed two populations one with ratios 5 and the other with ratios near the redfield ratios the low c n ratios suggest that physico chemical processes dominates these soils as supported by the absence of microbial activity and atmospherically deposited no3 with minimal post deposition modification the near redfield c n ratios can be explained by physical processes translocation of soc in the soils from snow meltwater or balanced microbial activity the latter is supported by the 13ccaco3 values of carbonates that suggest a contribution from microbially respired endolith derived organic matter providing indirect evidence of heterotrophic activity in permafrost soils from an ultraxerous environment

the grampian group a major late proterozoic clastic sequence in the central highlands of scotland a stratigraphic framework is proposed for the late proterozoic grampian group of the scottish highlands the grampian group is divided into three subgroups each defined by distinctive lithofacies associations reflecting different environments of deposition the thin ord ban subgroup which is locally developed at the base of the grampian group on speyside and strath dearn consists of shallow marine shelf sediments in association with concordant amphibolite sheets elsewhere the corrieyairack subgroup which is thickest around loch laggan forms the lower portion of the grampian group and comprises a thick turbiditic clastic sequence laid down in deeper water during rapid basin subsidence the glen spean subgroup comprises the upper part of the grampian group and is thickest in the atholl district it is composed of shallow water tidal and deltaic deposits marking a shallowing of the grampian group basin lateral facies changes and diachronous contacts are indicative of differential subsidence and the grampian group basin apparently developed and filled before the onset of regional subsidence which heralded deposition of the overlying dalradian sediments the possibility that the grampian group was unconformable on the structurally underly ing central highland division and glenshirra succession is currently unresolved

seismic discontinuity at the top of d a world wide feature considering the growing number of observations of a seismic discontinuity at the top of d some 300 km above the core mantle boundary we investigate the scenario of whether this feature could be global we show that the mean first arrivals of p waves as used to build global models can be fit by the two branches of a discontinuous model we argue that the intermittence of the detection of the reflector is due to lateral variations of a global discontinuity these observations put strong constraints on the type of chemical layering that could explain the discontinuity we speculate that the properties of the d discontinuity are better explained in terms of a new phase transition

ground surface temperature and humidity ground temperature cycles and the ice table depths in university valley mcmurdo dry valleys of antarctica in the upper mcmurdo dry valleys 90 of the measured ice table depths range from 0 to 80 cm however numerical models predict that the ice table is not in equilibrium with current climate conditions and should be deeper than measured this study explored the effects of boundary conditions air vs ground surface temperature and humidity ground temperature cycles and their diminishing amplitude with depth and advective flows darcy flow and wind pumping on water vapor fluxes in soils and ice table depths using the rego vapor diffusion model we conducted a series of numerical experiments that illustrated different hypothetical scenarios and estimated the water vapor flux and ice table depth using the conditions in university valley a small high elevation valley in situ measurements showed that while the mean annual ground surface temperature approximates that in the air the mean annual ground surface relative humidity 85 ice was significantly higher than in the atmosphere 50 ice when ground surface temperature and humidity were used as boundary conditions along with damping diurnal and annual temperature cycles within the sandy soil rego predicted that measured ice table depths in the valley were in equilibrium with contemporary conditions based on model results a dry soil column can become saturated with ice within centuries overall the results from the new soil data and modeling have implications regarding the factors and boundary conditions that affect the stability of ground ice in cold and hyper arid regions where liquid water is rare

stability of massive ground ice bodies in university valley mcmurdo dry valleys of antarctica using stable o h isotope as tracers of sublimation in hyper arid regions abstract to date studies of the stability of subsurface ice in the mcmurdo dry valleys of antarctica have been mainly based on climate based vapor diffusion models in university valley 1800 m a small glacier is found at the base of the head of the valley and adjacent to the glacier a buried body of massive ice was uncovered beneath 20 40 cm of loose cryotic sediments and sandstone boulders this study assesses the origin and stability of the buried body of massive ice by measuring the geochemistry and stable o h isotope composition of the ice and applies a sublimation and molecular diffusion model that accounts for the observed trends the results indicate that the buried massive ice body represents an extension of the adjacent glacier that was buried by a rock avalanche during a cold climate period the contrasting 18 o profiles and regression slope values between the uppermost 6 cm of the buried massive ice upward convex 18 o profile and s d 18o 5 1 and that below it progressive increase in 18 o and s d 18o 6 4 suggest independent post depositional processes affected the isotope composition of the ice the upward convex 18 o profile in the uppermost 6 cm is consistent with the ice undergoing sublimation using a sublimation and molecular diffusion model and assuming that diffusion occurred through solid ice the sublimation rate needed to fit the measured 18 o profile is 0 2 10 3 mm yr 1 a value that is more similar to net ice removal rates derived from 3 he data from cobbles in beacon valley till 7 0 10 3 mm yr 1 than sublimation rates computed based on current climate 0 1 0 2 mm yr 1 we suggest that the climate based sublimation rates are offset due to potential ice recharge mechanisms or to missing parameters particularly the nature and thermo physical properties of the overlying sediments i e temperature humidity pore structure and ice content grain size

deposition accumulation and alteration of cl no3 clo4 and clo3 salts in a hyper arid polar environment mass balance and isotopic constraints the salt fraction in permafrost soils sediments of the mcmurdo dry valleys mdv of antarctica can be used as a proxy for cold desert geochemical processes and paleoclimate reconstruction previous analyses of the salt fraction in mdv permafrost soils have largely been conducted in coastal regions where permafrost soils are variably affected by aqueous processes and mixed inputs from marine and stratospheric sources we expand upon this work by evaluating permafrost soil sediments in university valley located in the ultraxerous zone where both liquid water transport and marine influences are minimal we determined the abundances of cl no3 clo4 and clo3 in dry and ice cemented soil sediments snow and glacier ice and also characterized cl and no3 isotopically the data are not consistent with salt deposition in a sublimation till nor with nuclear weapon testing fall out and instead point to a dominantly stratospheric source and to varying degrees of post depositional transformation depending on the substrate from minimal alteration in bare soils to significant alteration photodegradation and or volatilization in snow and glacier ice ionic abundances in the dry permafrost layer indicate limited vertical transport under the current climate conditions likely due to percolation of snowmelt subtle changes in clo4 no3 ratios and no3 isotopic composition with depth and location may reflect both transport related fractionation and depositional history low molar ratios of clo3 clo4 in surface soils compared to deposition and other arid systems suggest significant post depositional loss of clo3 possibly due to reduction by iron minerals which may have important implications for oxy chlorine species on mars salt accumulation varies with distance along the valley and apparent accumulation times based on multiple methods range from 10 to 30 kyr near the glacier to 70 200 kyr near the valley mouth the relatively young age of the salts and relatively low and homogeneous anion concentrations in the ice cemented sediments point to either a mechanism of recent salt removal or to relatively modern permafrost soils 1 million years together our results show that near surface salts in university valley serve as an end member of stratospheric sources not subject to biological processes or extensive remobilization

a sequence stratigraphical approach to the understanding of basin history in orogenic neoproterozoic successions an example from the central highlands of scotland

mineralogy geochemistry and the development of ductile shear zones in the grampian slide zone of the scottish central highlands the grampian slide zone comprises a system of shear zones characterized by strain induced syn tectonic muscovitization growth of porphyroblasts of plagioclase garnet and muscovite concordant quartz veinlets and by later tectonic sillimanite and late to post tectonic kyanite traverses across shear zones in the central highland division show progressive modification of original gneissic fabrics demonstrating that metamorphism and gneissification preceded the shearing event mylonitization involved bulk mobilization of alkalies na ca k and trace elements ba rb sr ni cr zr accompanied by decreasing fe oxidation ratios and increasing shearing progressively changed the mineral chemistry of reversely zoned plagioclase zoned garnet and micas advanced syn shearing blastesis produced a suite of lenticular pegmatitic segregation veinlets in the mylonites a coeval suite of larger intrusive pegmatites represents more mobile material that has migrated through the shear zones the pegmatites and the mylonite matrices yield u pb monazite ages of c 806 ma corresponding to the precambrian knoydartian event in the moine rocks of the northern highlands the shear zones record compressional transport directed towards the nne and in the northern sector of the central highlands were reactivated by later caledonian extensional se directed movement the presence of the c 806 ma event in the grampian group challenges recent proposals that early deformation across the entire dalradian supergroup can be correlated with the c 590 ma tay nappe

a neoproterozoic multi phase rift sequence the grampian and appin groups of the southwestern monadhliath mountains of scotland the grampian and appin groups of the southwestern monadhliath mountains form the earliest known syn rift sequences of the scottish central highlands they were likely to have formed in an intracontinental setting and represent deposition of mixed clastic and carbonate shallow and deep marine strata the grampian group of the southern monadhliath mountains was deposited during a period of initial basin rifting nw se extension followed by a phase of thermal subsidence syn rift sediments comprise a 2 5 6 km thick turbidite system thermal subsidence brought about the basinward progradation of shallow marine shelf sediments resulting in the infilling of pre existing basin topography the overlying appin group commenced with deposition of a shallow marine sequence alternating between nearshore tidal sand and offshore mud deposition this formed in response to renewed rifting and concomitant subsidence accelerated rifting resulted in localized footwall uplift and erosion while sedimentation continued in the hanging wall areas resultant subsidence perhaps partly thermally driven caused gradual basin widening and produced an onlapping marine sequence there followed a period of progressive clastic deprivation when carbonates were precipitated and at the onset of anoxic conditions deposition of organic muds the fundamental structural elements responsible for the formation of the grampian and appin group basins were also influential in the orogenic evolution of the basin fill half graben fills were deformed to produce regionally extensive folds such as the stob ban craig a chail synform

excess ground ice of condensation diffusion origin in university valley dry valleys of antarctica evidence from isotope geochemistry and numerical modeling abstract this study investigates the origin and age of ground ice in the uppermost 1 m of permafrost in university valley one of the upper valleys in the mcmurdo dry valleys of antarctica in contrast to other regions in the mdv mean daily air and soil temperatures at the coring sites are always below 0 c which allows for unique cryogenic processes to occur in the two cores that were analyzed excess ground ice was measured throughout ranging between 23 and 85 isotope geochemical trends in the ice rich permafrost indicate that the ground in core 5 65 cm long and the uppermost 52 cm of core 7 originated from condensation diffusion of water vapor whereas the ground ice between 57 90 cm in core 7 originated from freezing of liquid water using numerical modeling we show that the excess ground ice of condensation diffusion origin formed by the long term thermal contraction expansion of the cryotic sediments which allowed for the ice content to exceed pore filling capacity absolute age estimates of the sandy loam sediments based on optically stimulated luminescence dating indicate that soils have been accreting at the site for at least the last 170 36 ka years and this places an upper limit to the age of the ground ice absolute soil ages allowed us to link the change in ground ice origin in core 7 which took place around 152 12 ka years with shifts in climate conditions since marine isotope stage 5e interglacial period our findings offer a new process of ground ice emplacement in sediments in cold dry environments and allow an alternative explanation regarding the enigmatic origin of excess ground ice identified by mars odyssey and phoenix in the northern martian plain which is that overfilled pore ice can form by vapor deposition and repeated thermal cycling without the presence of melt water

origin age and paleoenvironmental significance of carbonate precipitates from a granitic environment akshayuk pass southern baffin island canada this study documents the discovery of calcite crusts on the upper surface of clasts within morainic complexes in akshayuk pass southern cumberland peninsula baffin island a region underlain by granitic and gneissic rocks of the precambrian canadian shield strontium isotope ratios 87 sr 86 sr indicate that the major source of calcium is derived from the local dissolution of fracture filling calcite and a minor source is derived from silicate weathering the calcite crusts have 13 c values between 1 6 and 12 0 and 18 o values in the 13 0 and 7 9 range these values are highly enriched over the predicted isotopic values based on the 13 cdic and 18 o of the local water and temperature at which calcite precipitation occurred the isotopic enrichments are attributed to a combination of both equilibrium and kinetic evaporation and were verified experimentally the series of evaporative experiments indicate that kinetic evapo ration produces a far from equilibrium isotope effect on both the 13 c and 18 o composition of the precipitating calcite 13 ckie caco3 co2 between 20 2 and 40 5 vpdb 18 okie averaging 34 9 3 7 vsmow based on these re sults the formation of the calcite crusts is ascribed to the evaporation of stagnating ephemeral lakes and streams fol lowing the retreat of valley glaciers given the 1500 m difference in heights between the highland and the valley the katabatic winds originating from the penny ice cap can act as a catalyst to increase the rate of evaporation in ad dition radiocarbon dating of ten of these crusts yielded holocene ages 7640 cal calibrated bp to modern these re sults suggest that the maximum expansion of holocene valley glacier in akshayuk pass previously thought to have occurred during the little ice age is probably much older

chemostratigraphic correlation structure and sedimentary environments in the dalradian of the nw co mayo inlier nw ireland a thorough geochemical survey of the dalradian rocks in the nw mayo inlier has shown that each formation has a characteristic geochemical signature within regional geochemical trends that vary systematically with stratigraphic age this geochemical characterization enables correlation between geographically and tectonically isolated stratigraphic successions in the nw mayo inlier an almost complete succession of late proterozoic grampian appin and argyll group dalradian rocks structurally overlies earlier basement annagh division gneisses in structural blocks bounded by caledonian thrusts extensional low angle faults and steeply dipping faults grampian appin group relationships are better seen here than anywhere else in scotland or ireland but no tayvallich subgroup or southern highland group dalradian rocks are present comparison with chemostratigraphic data from scottish dalradian rocks reveals broadly similar chemical trends with time suggesting that the geological evolution of the dalradian took place in a related depositional environment probably an unbroken continental margin along the entire dalradian outcrop seen in both scotland and ireland

environmental setting micro morphologies and stable c o isotope composition of cold climate carbonate precipitates a review and evaluation of their potential as paleoclimatic proxies abstract given the growing interest in carbonate deposits from polar regions as paleoclimatic proxies this review paper first provides a classification of the various types of cold climate carbonate precipitates followed by a summary of the 13 c and 18 o composition of the carbonate deposits and parent water from which the carbonates precipitated the cold climate carbonate precipitates were classified into three broad categories powders crusts and speleothem the carbonate powders include those that precipitated in relation to aufeis aggradation cryogenic aufeis calcite and in relation to the growth of various annual perennial ice formations in freezing caves cryptocrystalline calcite and calcite pearls the carbonate crusts can be further subdivided based on their lithic environment those that precipitated on the upper surface of bedrock clasts i e subglacially precipitated calcite and evaporative calcite crusts those that are located on the underside of clasts i e pedogenic carbonates and those that precipitated in rock outcrop fissures i e endostromatolites the cold climate carbonate precipitates have a highly variable isotopic composition with 18 o values ranging between 6 5 and 28 vsmow and 13 c values in the 10 20 vpdb range however each type of carbonate precipitates has a specific 13 c and 18 o range suggesting that their environmental setting and the mechanism by which they formed controls their 13 c and 18 o signature it was found that carbonate deposits that precipitated under equilibrium physico chemical conditions had a 13 c value that is in equilibrium with that of the parent water while its 18 o composition was more variable as it is in part controlled by the temperature of reaction and by the 18 o and calcite saturation state of the parent water by contrast the 18 o composition of biologically precipitated carbonate deposits endostromatolites reflect that of the parent water while its 13 c composition was enriched over that of the parent water due to bacterial methanogenesis in the case of kinetically precipitated carbonate deposits the 18 o and 13 c values are out of equilibrium relative to that of the parent water due to the faster rate of reaction

endolithic microorganisms in the antarctic cold desert in the frigid desert of the antarctic dry valleys there are no visible life forms on the surface of the soil or rocks yet in certain rock types a narrow subsurface zone has a favorable microclimate and is colonized by microorganisms dominant are lichens of unusual organization they survive not by physiological adaptation to lower temperatures but by changing their mode of growth being able to grow between the crystals of porous rocks their activity results in mobilization of iron compounds and in rock weatherning with a characteristic pattern of exfoliation this simple ecosystem lacks both higher consumers and predators

hydrogeochemistry as an aid to geological interpretation the glen roy area scotland the hydrochemistry of first and second order streams sampled at a density of 1 km 2 has been used to investigate ways of enhancing information obtained during regional geological mapping the glen roy area of scotland is a pristine area with large variations in bedrock geology ranging from dalradian metasediments including carbonates to granite granodiorite and appinite rocks coarse grained lamprophyre but with relatively minor drift alkalinity hco 3 is used to determine the extent of water rock interaction with both silicate and carbonate rocks the ratio na cl is also used to measure the extent of silicate reaction dolomitic facies are picked out in areas with carbonate by mg mn fe and y are useful indicators of the weathering of biotite and garnet a strong and well defined hydrogeochemical anomaly of ba sr and k outline the outcrops of the appinites together with hco 3 these three elements define an extended nw se lineament strath ossian lineament which includes possible concealed areas of appinite the bicarbonate probably reflecting the presence of a carbonate aureole derived from mantle co 2 in particular the bedrock characteristics in poorly exposed ground can be inferred and information obtained on the volume of bedrock through which the water has passed

a late vendian age for the kinlochlaggan boulder bed dalradian the kinlochlaggan boulder bed occurs in neoproterozoic dalradian rocks of the grampian mountains of scotland it is currently thought to represent a glacial event c 800 ma unique in the north atlantic region and be part of a sequence correlated by different workers with either the grampian or appin groups we correlate the boulder bed with the port askaig tillite of vendian c 650 ma age and deduce that the sequence in which it occurs belongs to the younger argyll group the latter is preserved within the d2 kinlochlaggan synform and a previously unrecognized discontinuity of regional importance may separate inverted argyll group rocks from the underlying grampian group

the significance of the geal charn ossian steep belt in basin development in the central scottish highlands the geal charn ossian steep belt is a major composite synclinal structure cored by an upward facing appin group succession it is located at the margin of a west facing sedimentary basin where more than 8 km of grampian group sediment was deposited adjacent to an intrabasin structural high the high comprises mainly gneissose metasedimentary rocks the glen banchor succession which acted as the basement to the grampian and appin group rocks major unconformities are recognized at more than one level as the sedimentary basin successions onlapped onto the 9high9 the primary major upright folds and associated slides of the steep belt developed when considerable shortening was focused along the basin margin during the caledonian orogeny