To date, much effort has been made to overcome obstacles involved in inferring the provenance of sediments based on heavy mineral assemblages and geochemical fingerprints of minerals. These efforts ...have been concentrated on two main avenues. First, efforts have focused on disentangling physical and chemical properties of minerals and their behavior during transport. Second, efforts have centered on processing the obtained data in a way that takes into account the properties of heavy minerals and geochemical data sets. More specifically, to consider the limitations that arise from the nature of point count and compositional data. In this manuscript, a novel workflow for provenance is proposed based on the fact that point count data, although not compositional, carry compositional information. A case study is presented to infer the provenance of late Quaternary eolian sands from the southeastern Adriatic archipelago for which two different sources have been previously proposed. Heavy mineral data were represented in orthonormal log ratio coordinates. In this way, variables which compensate for hydraulic sorting and/or selective dissolution were obtained, with the major advantage that there are no restrictions for their use with statistical methods originally developed for real Euclidian space. To support conclusions based on heavy mineral data, we analyzed the geochemical composition of pyroxenes, which were also discriminated using a novel approach. As a result, the Albania-Montenegro shelf is determined to be a sediment source for eolian sands from Korčula, Lastovo and Mljet Islands. Hvar Island has a Neretva River signature, and Vis Island has a dominantly Neretva River signature with a small portion of sediments from the Albania-Montenegro shelf.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study deals with sand beaches of the SE Adriatic archipelago and Pelješac Peninsula. The beaches themselves, as well as their genetically related surroundings are taken into consideration, as ...both are critical for understanding beach features and processes. Two approaches have been followed in these two areas: the study of sediment composition including heavy mineral associations and the study of geology, morphology and sediment distribution. These features and their combination present the basis for interpretation of present-day processes, as well as for reconstructing how and where the beaches developed and why have they in some places disappeared.
Sediment composition of the studied beaches clearly indicates Pleistocene deposits as the principal sediment source. However, much of this supplied sediment has a short residence time on the beaches due to marine reworking and the bulk of the beach sediment arrives from the sea floor.
The positioning of the studied sand beaches at bayheads, their lengths and shapes, as well as their present status, have been influenced by several main factors. They include: (1) pre-Pleistocene tectonic deformations, (2) pre-Pleistocene weathering and erosion of carbonate sediments, mainly Cretaceous in age, (3) initial distribution of “soft” Pleistocene cover sediments, as well as (4) the history of their reduction and related decline in sediment source capacity or at some locations their complete disappearance. Other main factors are (5) the post-LGM sea-level rise and (6) two climatic events: an important pluvial period from 8.4 to 6 ka BP (maximum from 7 to 6 ka BP) and the transition to Mediterranean climate between 6 and 5.5 ka BP. Beaches with relatively high Pleistocene hinterland supply and correlative, relatively large widths seem to be quasi-stable or possibly even prograde. Beaches of small width and minor to negligible hinterland supply, or those completely deprived of it, suggest ongoing beach recession.
Suggested priorities for the protection of the beaches are directly related to the preservation of hinterland supply. In the case of beaches with negligible or no hinterland sediment supply replenishment projects can be considered.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The Palaeogene Promina Beds (PB), exposed in the Dinaric coastal range, is about a 2km thick heterogeneous succession representing a late sedimentary fill of the North Dalmatian foreland basin. The ...paper focuses on the middle part of the PB represented by a prominent transgressive unit. The study of this unit is based on field mapping, logging and facies analysis, as well as the investigation of stratigraphic surfaces and facies successions. The unit extends for more than 63km, along the entire basin. Deposition began transgressively over both alluvial deposits of the Lower PB and karstified basin basement. Along its extent the studied unit may be represented either by stacked (highfrequency), marine transgressive-regressive cycles, by lacustrine deposits, mainly limestones, or by a single, marine limestone unit. An ideal transgressive-regressive cycle includes a transgressive segment of limestones, and a regressive segment of storm-wave dominated shelf to gravelly beachface (coarsening-upward) deposits. Gravelly beaches are represented by several types. One of them included the steeply inclined, lower beachface which is situated below the intertidal zone. The cycles are separated by lower-rank discontinuity surfaces (flooding surfaces), while their two segments are separated by a lower-rank transgressive-regressive turnaround surface. Lacustrine deposits originated due to a rise in groundwater induced by a sea-level rise basinwards. The deposition of a single limestone unit resulted from a transgressive onlap over uplifted, Eocene and Cretaceous carbonates of the basin basement. The end of the transgression is marked by condensation processes indicated by glauconite, skeletal debris, planktonic foraminifera and hardgrounds, and a major transgressive-regressive turnaround. The subsequent evolution is almost uniform along the entire extent of the studied unit, and includes shelf to delta and shelf to beach cycles of the highstand. The studied allostratigraphic unit is here given a formal name: the Novigrad Alloformation.
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Scarce basin remnants of Cretaceous synorogenic sediments exposed in the Medvednica, Ivanščica, Žumberak Mts. and Samobor Hills of northern Croatia record the early orogenic history of the NW ...Dinarides. The provenance of sandstones from five clastic formations (Oštrc, Bistra, Kravljak, Vivodina and Glog) which cover a time span from Early to late Late Cretaceous was studied by combining petrography, whole-rock geochemistry, heavy mineral chemistry and detrital zircon fission track dating. These sediments record at least two major regional thermotectonic events which correlate well with those affecting both the Alps and the Tisza-Dacia unit to the north and east, and the central Dinaride region to the south. Short zircon fission track lag times in Barremian to Albian sediments indicate that continental fragments of the distal Adria plate margin underwent relatively fast, synsedimentary exhumation in the Early Cretaceous. Moreover, a clear dominance of Campanian zircon cooling ages (80–73 Ma) in Maastrichtian sandstones indicates detritus deriving from the erosion of newly and rapidly exhumed basement units which had undergone Late Cretaceous metamorphism in the Eastern Alps and/or the Tisza-Dacia region. Probably, the rapid Maastrichtian erosion generating metamorphic detritus occurred to a great extent on neighbouring Austroalpine basement units, and/or on the upper plate Tisza-Dacia unit during the subduction stage or the initial stages of the continent–continent collision with Adria. Development of the accretionary wedge probably resulted in a renewed availability of ophiolites for erosion within small and/or dynamically changing catchments, which can be deduced from the notable differences in reconstructed source lithologies for the coeval Glog and Vivodina formations. Combined evidence from sedimentary provenance indicators precludes the Dinaride (Adriatic) basement as a significant source for the Maastrichtian sediments.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The Island of Brusnik, located in the Central Adriatic Sea, is mainly known for its Triassic igneous rocks. However, it also contains Pleistocene conglomerates, limestones and Neptunian dikes, as ...well as Holocene rock debris, soil, and beach gravels. Quaternary sediments unconformably overlie tectonically disturbed Triassic basement. The majority of Pleistocene limestones, as well as the matrix of the conglomerates, are predominantly bioclastic grainstones and rudstones. Gastropod shells in these sediments retain their original aragonite mineralogy, and may also display their original colours. The majority of the conglomerates and limestones originated in lower beachface and shoreface environments. Similar sediments have not been identifi ed in the surrounding area and the Dinarides in general. Some of the Pleistocene sediments originated during MIS 5e of the Last Interglacial based on radiometric evidence. The island experienced uplift of about 30m during the Middle and Late Pleistocene and this process probably continued in the postglacial period. The combination of uplift and cyclic sea-level changes is envisaged to have resulted in an overall downstepping pattern of the Pleistocene deposits.
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Cr-spinel is a common heavy mineral in the sandstones of Cretaceous synorogenic sedimentary formations of the NW Dinarides, Croatia. The rocks occur in isolated exposures in the uplifted basement ...units of Medvednica, Ivanščica, Žumberak and Samobor Mountains near Zagreb. In this area, evidence of the early Alpine evolution of the Dinarides is obscured due to strong dismemberment of pre-Tertiary tectonostratigraphic units resulting from an intense tectonic history, as well as due to the widespread sedimentary cover of the Pannonian Basin. Electron microprobe analyses of detrital Cr-spinels from the Oštrc Formation reveal that in the Early Cretaceous the ophiolitic source area was predominantly composed of harzburgite peridotites and associated cumulate rocks, which developed in a supra-subduction zone setting. The supply of Cr-spinels with the same chemical signature remained dominant until the end of the Cretaceous, suggesting that exposed remnants of the same ophiolite belt persisted through the Cretaceous and/or that recycling was significant. Similarities with data reported from the Northern Calcareous Alps and the Transdanubian Central Range imply that a rather extensive harzburgitic ophiolite belt probably extended along the Adriatic margin during the Early Cretaceous. A slight trend of increasing variation in the Cr# is observed from the Early to the latest Cretaceous, suggesting that the source areas became more heterogeneous with the ongoing Cretaceous tectonic evolution. Differences in Cr-spinel compositions in two contemporaneous latest Cretaceous formations are well in line with existing data on heavy mineral proportions, which together identify contrasting hinterland geology for these formations and strongly suggest the coeval existence of two separate basins.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Mt. Promina became famous for its coal mines, vertebrate remains and fossil flora, and for the use of its name in denoting sediments covering a wide area of the Dinaric coastal range. The Promina ...Beds of the type area, Mt. Promina, are up to 1 km thick and evolved in the context of propagating Dinaric deformation towards the foreland. They consist of eight sedimentary units differing in facies, i.e. depositional environments and systems, which include alluvial, lacustrine, deltaic, lagoonal and shelf deposits. The sedimentary units constitute three depositional cycles. Cycle I is represented by a late lowstand alluvium, while Cycles II and III consist of trasgressive and highstand (regressive) systems tracts. Cycle III also includes a coastal onlap of limestones and an alluvial onlap. Trasgressive tracts are specific in being represented by lacustrine deposits and having non-erosive bases. Falling-stage sediments have not been identified. The Promina Beds of Mt. Promina represent an example of sedimentary and sequence evolution at a foreland basin margin. The evolution of this margin is characterised by structural and stratigraphic complexities including syndepositional folding, growth strata, angular unconformities, intraformational faulting, alluvial and marine onlaps onto deformed basement, and tectonically induced, proximal-distal variations in facies and sediment thickness. The origin of lacustrine transgressive tracts may have been related to backtilting in the proximal part of the basin. High sediment supply and subsidence pulses are proposed to have been the two main factors which shaped the depositional styles, sequence development and distribution of sediments. The dominant role of tectonism in the sedimentary evolution was related to the position of the area within deforming; marginal parts of the foreland basin, situated in close vicinity to the main, active Dinaric thrust units.
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This study examines how and why the accumulation and preservation of aeolian sands are influenced by the character of karstic basement landforms. The studied examples are Late Pleistocene aeolian ...sands and underlying karstified carbonates of Southeastern Adriatic islands. To address this issue the spacial relationship between karstified bedrock and aeolian cover, aeolian and associated fluvial facies, as well as the petrography of sands, including heavy minerals and bioclasts (especially foraminifera) have been studied. Specific landforms of the carbonate basement originated as a consequence of deformation, karstification and locally with additional influence of fluvial processes. They are located at different elevations above today's sea-level, as well as above ancient sand pathways towards the islands, which are now below sea-level. The karst depressions critically influenced the accumulation and preservation of aeolian sands. The depressions represented traps for accumulation and shelters for preservation of these sands. The closed type karst depressions include large examples which contain successions displaying the most complete stratigraphic record, located in the approximate centre of the depression. The open type karst depression is characterised by a partial removal of sands which were exported down-valley.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Mt. Promina became famous for its coal mines, vertebrate remains and fossil flora, and for the use of its name in denoting sediments covering a wide area of the Dinaric coastal range. Up to 1 km ...thick Promina Beds of the type area, Mt. Promina, evolved in the context of propagating Dinaric deformation towards the foreland. They consist of eight sedimentary units differing in facies, i.e. depositional environments and systems, which include alluvial, lacustrine, deltaic, lagoonal and shelf deposits. The sedimentary units constitute three depositional cycles. Cycle I is represented by a late lowstand alluvium, while Cycle II and III consist of transgressive and highstand (regressive) systems tracts. Cycle III also includes a coastal onlap of limestones and an alluvial onlap. Transgressive tracts are specific in being represented by lacustrine deposits and having non-erosive bases. Falling-stage sediments have not been identified. The Promina Beds of Mt. Promina represent an example of sedimentary and sequence evolution at a foreland basin margin. The evolution of this margin is characterised by structural and stratigraphic complexities including syndepositional folding, growth strata, angular unconformities, intraformational faulting, alluvial and marine onlaps onto deformed basement, and tectonically induced, proximal-distal variations in facies and sediment thickness. The origin of lacustrine transgressive tracts may have been related to backtilting in the proximal part of the basin. High sediment supply and subsidence pulses are proposed to have been the two main factors which shaped depositional styles, sequence development and distribution of sediments. The dominant role of tectonism in the sedimentary evolution was related to the position of the area within deforming, marginal parts of the foreland basin, situated in the close vicinity to the main, active Dinaric thrust units.
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The composition of beach sands from the Islands of Rab and Susak (northern Adriatic) has been studied in order to determine how individual beaches are supplied with detritus. The beaches on both ...islands are composed of quartz dominated siliciclastic sand, with subordinate carbonate content. Three end-member heavy mineral assemblages have been identified among the studied beach sands, each one associated with a specific source rock: (1) a garnet dominated assemblage and (2) a zircon, rutile and tourmaline dominated assemblage on Rab Island, as well as (3) an assemblage dominated by unstable minerals on Susak Island. Sands from individual beaches contain one of these specific assemblages or display a mixing of two varieties. The end-member assemblages are very comparable with those of Eocene and Pleistocene sediments which crop out on the two islands, identifying them as the principal sources of detritus. Cretaceous and Eocene carbonate rocks, although present to a considerable extent in the study area, has shown to be a negligible source of sandy material. Thus, the supply of detritus to the beaches is primarily controlled by erosion of siliciclastic rocks in the immediate or nearby hinterland.
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