The history of predation is recorded primarily from drilling in Cenozoic invertebrates. Quantitative data are uncommon from the Triassic, a period before the appearance and radiation of many known ...drill hole producers such as various gastropod families and octopods. We present quantitative evidence of drilling from the Late Triassic (Carnian) Cassian Formation of Italy and the Middle Triassic (Anisian) Lower Muschelkalk of Poland, documenting the first drill holes in Triassic brachiopods. A single brachiopod with a cylindrical, complete drill hole was found in a brachiopod sample from of Poland (drilling percentage=0.3%, n=365). The Cassian Formation yielded drill holes in gastropods, bivalves, and brachiopods, indicating that more species are drilled than was known previously. The minimum drilling percentage exclusive of incomplete drill holes of a sample from the Stuores Wiesen (Cassian Formation) is 1.7% (n=116.5). Prey selectivity is evident: complete drill holes are primarily present in one gastropod species, Polygyrina lommeli (11.8% of specimens with a complete drill hole), whereas other common species were not drilled. Single drill holes in brachiopods are cylindrical and complete and may be predatory in origin. Multiple drill holes in mollusks are common, and drill holes are parabolic and often incomplete with a central boss, resembling the shape of drill holes produced by extant naticid gastropods. A survey of the Paleozoic literature showed that such drill holes are also present in Devonian and Carboniferous brachiopods. However, naticids did not evolve until the Cretaceous so we propose the term “drill hole convergence” for similar-shaped drill holes produced by different organisms. The Triassic parabolic drill holes are not caused by domicile-seeking or boring organisms. Instead, we favor a predatory origin of these drill holes, but we cannot entirely rule out parasitism. Surveying other Triassic invertebrate assemblages should yield more evidence of drilling.
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•We report on rare drill holes in mollusks and brachiopods from the Triassic.•The drill holes are most likely made by predators or, perhaps, parasites.•Most drill holes resemble those produced by modern naticid gastropods.•Similar holes also occur in the Paleozoic, when naticids were also absent.•“Drill hole convergence”: similar-shaped holes drilled by different organisms.
Little is known about water in nominally anhydrous minerals of orogenic garnet peridotite and enclosed metabasic rocks. This study is focused on peridotite‐hosted eclogite and garnetite ...(metarodingite) from the Erzgebirge (EG), Germany, and the Lepontine Alps (LA), Switzerland. Newly discovered, peridotite‐hosted eclogite in the Erzgebirge occurs in the same ultra‐high pressure (UHP) unit as gneiss‐hosted coesite eclogite, from which it is petrologically indistinguishable. Garnet is present in all mafic and ultramafic high pressure (HP) rocks providing for an ideal proxy to compare the H2O content of the different rock types. Garnet composition is very similar in EG and LA samples and depends on the rock type. Garnet from garnetite, compared to eclogite, contains more CaO (garnetite: 10.5–16.5 wt%; eclogite: 5–11 wt%) and is also characterized by an anomalous REE distribution. In contrast, the infrared (IR) spectra of garnet from both rock types reveal the same OH absorption bands that are also identical to those of previously studied peridotitic garnet from the same locations. Two groups of IR bands, SW I (3,650 ± 10 cm−1) and SW II (3,570–3,630 cm−1) are ascribed to structural hydroxyl (colloquially ‘water’). A third, broad band is present in about half of the analysed garnet domains and related to molecular water (MW) in submicroscopic fluid inclusions. The primary content of structural H2O, preserved in garnet domains without fluid inclusions (and MW bands), varies systematically—depending on both the location and the rock type. Garnet from EG rocks contains more water compared to LA samples, and garnet from garnetite (EG: 121–241 wt.ppm H2O; LA: 23–46 wt.ppm) hosts more water than eclogitic garnet (EG: 84 wt.ppm; LA: 4–11 wt.ppm). Higher contents of structural water (SW) are observed in domains with molecular water, in which the SW II band (being not restricted to HP conditions) is simultaneously enhanced. This implies that fluid influx during decompression not only led to fluid inclusions but also favoured the uptake of secondary SW. The results signify that garnet from all EG and LA samples was originally H2O‐undersaturated. Combining the data from eclogite, garnetite and previously studied peridotite, H2O and CaO are positively correlated, pointing to the same degree of H2O‐undersaturation at peak metamorphism in all rock types. This ubiquitous water‐deficiency cannot be reconciled with the derivation of any of these rocks from the lowermost part of the mantle wedge that was in contact with the subducting plate. This agrees with the previously inferred abyssal origin for part of the rocks from the LA (Cima di Gagnone). A similar origin has to be invoked for the Erzgebirge UHP unit. We suggest that all mafic and ultramafic rocks of this unit not only shared the same metamorphic evolution but also a common protolith origin, most probably on the ocean floor. This inference is supported by the presence of peridotite‐hosted garnetite, representing metamorphosed rodingite.
Rad sagledava ranije poznate i nepoznate grobne nalaze kasnog
10. i 11. stoljeća iz Šenkovca, Sv. Jurja u Trnju i Sv. Martina na
Muri u Međimurju. Njihovom, prvi put cjelovitom obradom, na
jednome ...mjestu upotpunjena su saznanja o procesima koji se
događaju između Drave i Mure te širem prostoru istočnih Alpi
i Panonske nizine. Za prepoznavanje i utvrđivanje regionalnog
okvira bilo je potrebno kartiranje analogija za grobne nalaze.
Stavljanje u povijesni kontekst pružilo je neophodne determinante
za razumijevanje tog prostora, a dodatni ekskursi o transformacijama
ranoga srednjeg vijeka u međurječju Drave i Mure
upotpunili su interpretaciju grobnih nalaza.
The late Eocene-to-early Oligocene Taveyannaz Formation is a turbidite series deposited in the Northern Alpine Foreland Basin (close to the Alpine orogenic front). Double dating of zircons with the ...fission-track and the U–Pb methods is applied on samples from the Taveyannaz Formation to reconstruct the exhumation history of the Central-Western Alps and to understand the syn-collisional magmatism along the Periadriatic lineament. Three samples from this unit show similar detrital zircon fission-track age populations that center at: 33–40 Ma (20%); 69–92 Ma (30–40%); and 138–239 Ma (40–50%). The youngest population contains both syn-volcanic and basement grains. Combined with zircon U–Pb data, it suggests that the basement rocks of Apulian-affinity nappes (Margna Sesia, Austroalpine) were the major sources of detritus, together with the Ivrea Zone and recycled Prealpine flysch, that contributed debris to the Northern Alpine Foreland Basin. Furthermore, the rocks of the Sesia–Lanzo Zone or of equivalent units exposed at that time presumably provided the youngest basement zircon fission-track ages to the basin. The Biella volcanic suite was the source of volcanogenic zircons. Oligocene sediment pathways from source to sink crossed further crystalline basement units and sedimentary covers before entering the basin from the southeast. The lag times of the youngest basement age populations (volcanic zircons excluded) are about 11 Myr. This constrains average moderate-to-high exhumation rate of 0.5–0.6 km/Myr in the pro-side of the orogenic wedge of the Central Alps during the late Eocene to early Oligocene.
Geochemical signatures and carbonate microfacies highlight contrasts between two distinctive mid–late Triassic reef communities in the Dolomite Alps, Italy. In the first community, sponges, ...bryozoans, calcified cyanobacteria and problematic organisms (Archaeolithoporella, Shamovella), together with a variety of micritic fabrics, formed compact reefs in high energy shallow-water at the margins of high-rise Ladinian–Carnian carbonate platforms. Debris from these margins created steep foreslopes, and some large blocks of the allochthonous material (Wengen–Cassian formations, Cipit Boulders) were buried in basinal shales that protected them from subsequent alteration and regional dolomitization. In the second and slightly younger community, small Carnian patch reefs (Heiligkreuz Formation, Alpe di Specie) developed in quieter shallow water, where they too were protected against alteration by enclosing shales. They were constructed mainly by scleractinian corals, sponges and red algae, and contain relatively large framework cavities with clotted-peloidal micrite. These early examples of coralgal reefs have broad similarities to present-day examples, whereas the community represented by the Cipit Boulders has more in common with Late Permian reefs.
Both bioconstructions preserve primary microfabrics and biomarkers. The Cipit Boulder samples contain bacterial, mainly cyanobacterial biomarkers, lack specific molecules typical of sulfate-reducing bacteria (SRB), and have Rare Earth Element (REE) values indicative of oxic conditions. These signatures are consistent with their original high-energy platform margin location, compact structure, and presence of calcified cyanobacteria such as Cladogirvanella and Girvanella. In contrast, the coralgal patch reefs contain SRB biomarkers, lack specific molecules typical of cyanobacteria, and have REE values indicative of sub-oxic conditions. These signatures are consistent with their lower energy depositional conditions and well-developed skeletal framework that created protected low-oxygen micro-habitats. The SRB biomarkers can be linked to the associated clotted-peloidal fabrics which resemble those commonly present in younger coral-reef frameworks. These details of redox conditions and bacterial processes underscore the important biotic, structural and environmental changes that affected shallow marine reefs during the Triassic.
•The first combined biomarker and REE analyses of contrasting Triassic reef types.•High rise reefs have cyanobacterial biomarkers and oxic (REE) distributions.•Quieter water reefs have BSR biomarkers and sub-oxic REE signatures.•These reefs mark a key transition from Paleozoic- to modern-type coralgal reefs.
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•New compositional and isotopic constraints on the origin of chromitites at Finero.•Laurite have similar unradiogenic 187Os/188Os values and TRD ages ca. 450Ma or older.•Trace-element ...signatures of zircons support carbonatite nature of metasomatism.•Zircon U-Pb ages record prolonged mantle metasomatism from ∼310Ma to 190Ma.•Zircon Hf-isotope composition implies derivation from a relatively old source (ca. 0.9Ga).
Chromitites enclosed within metasomatised Finero phlogopite peridotite (FPP) contain accessory platinum-group minerals, base metal (BM) sulfides, baddeleyite, zircon, zirconolite, uraninite and thorianite. To provide new insights into mantle-crustal interaction in the Finero lithosphere this study evaluates (1) the mineral chemistry and Os-isotope composition of laurite, (2) the crystal morphology, internal structure, in-situ U-Pb, trace-element and Hf-isotope data of zircon from two chromitite localities at Alpe Polunia and Rio Creves. The osmium isotope results reveal a resticted range of ‘unradiogenic’ 187Os/188Os values for laurite at Alpe Polunia (0.1247–0.1251, mean 0.1249±0.0001). Re-Os model ages (TRD) of laurite reflect an Early Paleozoic partial melting event (ca 450Ma or older), presumably before the Variscan orogeny. The Os isotopic composition of laurite/chromitite probably preserves their mantle signature and was not affected by later metasomatic processes. U-Pb and Hf-isotope data show that the Finero chromitites have distinct zircon populations with peculiar morphology, internal cathodoluminescence textures, trace-element composition and an overall U-Pb age span from ∼310Ma to 190Ma. Three age peaks at Rio Creves (220±4Ma, 234.2±4.5Ma and 277.5±3.2Ma) are consistent with a prolonged formation and multistage zircon growth, in contrast to the common assumption of a single metasomatic event during chromitite formation. The trace-element signatures of zircons are comparable with those of mantle-derived zircons from alkaline ultramafic rocks, supporting the carbonatitic nature of the metasomatism. Hf-isotope compositions of the Finero zircons, with εHf values ranging mainly from −3 to +1, are consistent with crustal input during metasomatism and could indicate that the parental melts/fluids were derived from a relatively old source; the minimum estimates for Hf model ages are 0.8–1.0Ga. Our findings imply that mantle rocks and metasomatic events at Finero have a far more complex geological history than is commonly assumed.
The Post-Forum Study Tour following the 4th World Landslide Forum 2017 in Ljubljana (Slovenia) focuses on the variety of landslide forms in Slovenia and its immediate NW surroundings, and the ...best-known examples of devastating landslides induced by rainfall or earthquakes. They differ in complexity of the both surrounding area and of the particular geological, structural and geotechnical features. Many of the landslides of the Study Tour are characterized by huge volumes and high velocity at the time of activation or development in the debris flow. In addition, to the damage to buildings, the lives of hundreds of people are also endangered; human casualties occur. On the first day, we will observe complex Pleistocene to recent landslides related to the Mesozoic carbonates thrust over folded and tectonically fractured Tertiary siliciclastic flysch in the Vipava Valley (SW Slovenia), serving as the main passage between the Friulian lowland and central Slovenia, and thus also an important corridor connecting Northern Italy to Central Europe. A combination of unfavourable geological conditions and intense short or prolonged rainfall periods leads to the formation of different types of complex landslides, from large-scale deep-seated rotational and translational slides to shallow landslides, slumps and sediment gravity flows in the form of debris or mudflows. The second day of the study tour will be held in the Soča River Valley located in NW Slovenia close to the border with Italy, where the most catastrophic Stože landslide in Slovenia recently caused the deaths of seven people, and the nearby Strug landslide, which is a combination of rockfall, landslide and debris flow. The final day of the Post-Forum Study Tour will start in the Valcanale Valley located across the border between Slovenia and Italy, severely affected by a debris flow in August 2003. The flow caused the deaths of two people, damaged 260 buildings; large amounts of deposits blocked the A23 Highway, covering both lanes. In Carinthia (Austria), about 25 km west of Villach, the Dobrač/Dobratsch multiple scarps of prehistoric and historic rockslides will be observed. Dobratsch is a massive mountain ridge with a length of 17 km and a width of 6 km, characterized by steep rocky walls. The 3-day study tour will conclude with a presentation of the Potoška planina landslide, a slide whose lower part may eventually generate a debris flow and therefore represents a hazard for the inhabitants and for the infrastructure within or near the village of Koroška Bela.
The Alps are one of the most sensitive regions in Europe, and their future development represents a challenge that demands the cooperation of various experts, the business world, politics, and ...society, as well as the people living there. The Interreg IIIB project DIAMONT, which took place from 2005 to 2008, also addressed Alpine developmental challenges. This monograph presents the basic results of the project, supported by the broader theoretical framework of regional and sustainable development. We first present the cultural differences in the Alps and their influence on sustainable regional development. This is followed by the results of a Delphi analysis, which helped reveal the basic development tendencies in the Alps, and then we discuss appropriate indicators for regional development and harmonizing data. Attention is then dedicated to regional development instruments and the participative process, which is essential for attaining truly sustainable development. Finally, we present a Slovenian perspective on these issues.
The crystal chemistry of a cafarsite sample from the fengitic orthogneisses of the Mt. Leone-Arbola nappe (Lower Penninic), forming the central body of Mount Cervandone and cropping out both in ...Switzerland and Italy (Alpe Devero area, Verbano–Cusio–Ossola province), was investigated by electron microprobe analysis in wavelength-dispersive mode (EPMA-WDS), single-crystal Raman spectroscopy, and single-crystal X-ray and neutron diffraction at 293 K. The sample of cafarsite of this study was found experimentally to be anhydrous and the chemical formula obtained on the basis of the EPMA-WDS data and structural refinements is the following:
Ca1,Ca2
(Ca
15.56
Na
0.44
)
Σ16
Fe1
(Na
0.53
Fe
2+
0.17
REE
0.30
)
Σ1.00
Mn1,Ti,Fe2
(Ti
7.46
Fe
3+
4.47
Fe
2+
3.20
Mn
2+
0.85
Al
0.11
)
Σ16.11
As1,As2,As3
(AsO
3
)
28
F
F, with the general chemical formula Ca
16
(Na,Fe
2+
,REE)(Ti, Fe
3+
,Fe
2+
,Mn
2+
,Al)
16
(AsO
3
)
28
F or Ca
16
(Na,Fe
2+
,REE)(Ti,Fe
3+
,Al)
12
(Fe
2+
,Mn)
4
(AsO
3
)
28
F. Our experimental findings show that fluorine, which was unconsidered in the previous studies, is a key element. The anhydrous nature of this sample is also confirmed by its Raman spectrum, which does not show any evidence of active bands ascribable to the O–H stretching region. The X-ray and neutron structure refinements provide a structure model that is partially in agreement with the previous experimental findings. The space group (i.e.
Pn
3) and the unit-cell constant i.e. 15.9507(4) Å are conform to the literature data, but the structure of cafarsite, here refined, contains the following building units: three independent AsO
3
groups (trigonal pyramids), one CaO
6
F polyhedron, one CaO
8
polyhedron, two independent (Ti,Fe)O
6
octahedra, one (Na,Fe,REE)O
8
polyhedron, and one (Mn,Fe)O
6
octahedron. Connections among polyhedra are mainly due to edge- or vertex-sharing; the AsO
3
groups are not connected to each other.
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