Crustal-scale magmatic systems during intracontinental strike-slip tectonics: U, Pb and Hf isotopic constraints from Permian magmatic rocks of the Southern Alps

The Southern Alps host volcano-sedimentary basins that formed during post-Variscan extension and strike-slip in the Early Permian. We present U-Pb ages and initial Hf isotopic compositions of magmatic zircons from silicic tuffs and pyroclastic flows within these basins, from caldera fillings and from shallow intrusions from a 250km long E-W transect (Bozen-Lugano-Lago Maggiore) and compare these with previously published data. Basin formation and magmatism are closely related to each other and occurred during a short time span between 285 and 275Ma. The silicic magmatism is coeval with mafic intrusions of the Ivrea-Verbano Zone and within Austroalpine units. We conclude that deep magma generation, hybridisation and upper crustal emplacement occurred contemporaneously along the entire transect of the Southern Alps. The heat advection in the lower crust by injected mantle melts was sufficient to produce crustal partial melts in lower crustal levels. The resulting granitoid melts intruded into the upper crust or rose to the surface forming large caldera complexes. The compilation of Sr and Nd isotopic data of these rocks demonstrates that the mantle mixing endmember in the melts may not be geochemically enriched but has a depleted composition, comparable to the Adriatic subcontinental mantle exhumed to form the Tethyan sea floor during Mesozoic continental breakup and seafloor spreading. Magmatism and clastic sedimentation in the intracontinental basins was interrupted at 275Ma for some 10-15millionyears, forming a Middle Permian unconformity. This unconformity may have originated during large-scale strike-slip tectonics and erosion that was associated with crustal thinning, upwelling and partial melting of mantle, and advection of melts and heat into the crust. The unconformity indeed corresponds in time to the transition from a Pangea-B plate reconstruction for the Early Permian to the Late Permian Pangea-A plate assembly (Muttoni etal. in Earth Planet Sci Lett 215:379-394, 2003). The magmatic activity would therefore indicate the onset of >2,000km of strike-slip movement along a continental-scale mega-shear, as their model suggest

Bio- and chronostratigraphy of the Middle Triassic Reifling Formation of the westernmost Northern Calcareous Alps

New finds of fossils including bivalves, ammonoids, brachiopods and palynomorphs from the Middle Triassic Reifling Formation significantly improve the age assignment for this unit in Liechtenstein and Vorarlberg. The lower part of the Reifling Formation is tentatively referred to the Late Anisian Paraceratites trinodosus Zone and somewhat older levels, whereas the uppermost part reaches the Ladinian Protrachyceras archelaus Zone (ammonoid zonation). The Middle Triassic successions of the study area are correlated with the coeval South Alpine reference section at Bagolino (Brescian Prealps), which also bears the Ladinian GSSP. The comparison shows that the Reifling Formation in the study area is age-equivalent with the South Alpine Prezzo Limestone and the Buchenstein Formation. A volcanoclastic layer in the upper part of the Reifling Formation at Flexenpass yields a U-Pb zircon age of 239.3 +/- 0.2 Ma. This value is slightly older than previously published minimum ages from equivalent horizons in the Southern Alps; the difference is thought to be mainly due to improved pre-treatment of zircons (annealing/chemical abrasion), which significantly reduces the effects of Pb loss. The new radio-isotope age further constrains the stratigraphical age of the Reifling Formation and supports the proposed biostratigraphy-based correlation of Middle Triassic successions in the Eastern and Southern Alp

Ammonoids of the middle/late Anisian boundary (Middle Triassic) and the transgression of the Prezzo Limestone in eastern Lombardy-Giudicarie (Italy)

This study documents ammonoids with a precise stratigraphic control at the middle/late Anisian (Pelsonian/Illyrian) boundary from a new locality in eastern Lombardy-Giudicarie (Monte Guglielmo) and from classical sections in Giudicarie. These ammonoid faunas allow revising the taxonomic interpretation of Ceratites cimeganus Mojsisovics 1882 and of the genus Paraceratites Hyatt 1900. Ceratites cimeganus is here assigned to the North American genus Rieppelites Monnet & Bucher 2005. In eastern Lombardy-Giudicarie, R. cimeganus is diagnostic of a distinct biochronological unit (cimeganus Zone) bracketed between the older Bulogites zoldianus Zone and the younger Judicarites euryomphalus-Paraceratites trinodosus zones. The recognition of this cimeganus Zone significantly improves worldwide correlation since it is recognized in several other Tethyan basins (Dolomites, Northern Calcareous Alps) as well as in North America (Nevada). These new data allow a redefinition of the middle/late Anisian boundary in the western Tethys, which is here intercalated between the zoldianus and cimeganus zones. This limit is marked by a clear ammonoid turnover (e.g. disappearance of Acrochordiceras and Balatonites, appearance of Rieppelites). Finally, the presence of sections including the cimeganus Zone in eastern Lombardy-Giudicarie allow the establishment of local gaps in sedimentation, which may reflect the regional and important transgression of the pelagic Prezzo Limestone over the shallow water platform carbonates of a "Camorelli-Dosso dei Morti barrier”, as also underlined by the spatial distribution of brachiopod lumachella

Integrated Anisian–Ladinian boundary chronology

We report magnetostratigraphic and biostratigraphic data from the Seceda core and the correlative outcrop section from the Dolomites of northern Italy. The Seceda rock succession consists of Tethyan marine limestones and radiometrically dated volcaniclastic layers of the Buchenstein Beds of Middle Triassic age (∼238–242 Ma). The Seceda outcrop section was correlated to coeval sections from the literature using magnetic polarity reversals and a selection of laterally traceable and isochronous lithostratigraphic marker beds. This allowed us to import the distribution of age-diagnostic conodonts, ammonoids, and daonellas from these sections into a Seceda reference stratigraphy for the construction of an integrated biochronology extending across a consistent portion of the Anisian–Ladinian boundary interval. Among the three options selected by the Subcommission for Triassic Stratigraphy to establish the Ladinian Global Stratigraphic Section and Point, we propose to adopt the level containing the base of the Curionii ammonoid Zone at Bagolino (Southern Alps, Italy) because this level is closely associated with a global means of correlation represented by the base of polarity submagnetozone SC2r.2r. The first occurrence of Neogondolella praehungarica in the Dolomites predates slightly the base of the Curionii Zone and can be used to approximate the Anisian–Ladinian boundary in the absence of ammonoids

Geometry and chronology of growth and drowning of Middle Triassic carbonate platforms (Cernera and Bivera/Clapsavon) in the Southern Alps (northern Italy)

Abstract.: The depositional architecture and the geometric relationships between platform-slope deposits and basinal sediments along with paleontological evidence indicate the time interval of the younger Anisian Reitziites reitzi ammonoid zone to largely represent the main stage of platform aggradation at the Cernera and Bivera/Clapsavon carbonate platforms. Published and new U-Pb age data of zircons from volcaniclastic layers bracketing the stratigraphic interval of platform growth constrain the duration of platform evolution to a time span shorter than 1.8±0.7m.y., probably in the order of 0.5-1m.y., reflecting fast rates of vertical platform aggradation exceeding 500 m/m.y. In the range of growth potentials for shallow-water carbonate systems estimated in relation to the time span of observation, this high rate is in agreement with values for short intervals of 105-106yrs (e.g., Schlager 1999). After drowning, the platforms at Cernera and Bivera/Clapsavon were blanketed by thin pelagic carbonates. On the former platform flanks the draping sediments in places comprise red nodular pelagic limestones (Clapsavon Limestone) similar in facies to the Han Bulog Limestones occurring elsewhere in Middle Triassic successions of the Mediterranean Tethys. The drowning of vast areas of former carbonate platforms possibly triggered the onset of bottom-water circulation in adjacent basins as suggested by the abrupt transition from laminated to bioturbated pelagic nodular limestones in the Buchenstein Formation which occurred close to the time of initial platform submergence. During the Late Ladinian the topographic features of the drowned platforms were onlapped by rapidly deposited, predominantly clastic successions including coarse breccias and volcanic rocks sealing and preserving the peculiar stratigraphic settin

THE SECEDA DRILL HOLE IN THE MIDDLE TRIASSIC BUCHENSTEIN BEDS (LIVINALLONGO FORMATION, DOLOMITES, NORTHERN ITALY) A PROGRESS REPORT

First results and basic geological information of the Seceda Coring Project are reported. The Seceda project started with drilling of a well for scientific purposes. The core material is currently studied by an international group of geoscientists from different universities. Fundamental topics of the project are a thorough sedimentological and cyclostratigraphic analysis of the complete succession of Middle Triassic pelagic Buchenstein Beds in the northwestern Dolomites (Southern Alps, Italy) as well as their temporal relationship with coeval carbonate platforms. Complementary studies focus on stratigraphic correlation tools including bio-, litho- and magnetostratigraphy.&nbsp

Mesoscopic magnetism in dielectric photonic crystal meta materials: topology and inhomogeneous broadening

We consider meta materials made from a two-dimensional dielectric rod-type photonic crystal. The magnetic response is studied within the recently developed homogenization theory and we in particular study the effects of topology and inhomogeneous broadening. While topology itself mainly affects the Mie resonance frequency we find that the dispersion in the topological radius R of the dielectric rods may lead to significant inhomogeneous broadening and suppression of the negative-mu phenomena for dR/R0 >> epsilon''/epsilon', with epsilon=epsilon'+i*epsilon'' being the relative dielectric function of the rods.Comment: 13 pages including 1 table and 5 figure

I-BEAT: New ultrasonic method for single bunch measurement of ion energy distribution

The shape of a wave carries all information about the spatial and temporal structure of its source, given that the medium and its properties are known. Most modern imaging methods seek to utilize this nature of waves originating from Huygens' principle. We discuss the retrieval of the complete kinetic energy distribution from the acoustic trace that is recorded when a short ion bunch deposits its energy in water. This novel method, which we refer to as Ion-Bunch Energy Acoustic Tracing (I-BEAT), is a generalization of the ionoacoustic approach. Featuring compactness, simple operation, indestructibility and high dynamic ranges in energy and intensity, I-BEAT is a promising approach to meet the needs of petawatt-class laser-based ion accelerators. With its capability of completely monitoring a single, focused proton bunch with prompt readout it, is expected to have particular impact for experiments and applications using ultrashort ion bunches in high flux regimes. We demonstrate its functionality using it with two laser-driven ion sources for quantitative determination of the kinetic energy distribution of single, focused proton bunches.Comment: Paper: 17 Pages, 3 figures Supplementary Material 16 pages, 7 figure

Neonatal screening: identification of children with 11β-hydroxylase deficiency by second-tier testing

21-Hydroxylase deficiency (21-OHD) is the target disease of newborn screening for congenital adrenal hyperplasia (CAH). We describe the additional detection of patients suffering from 11β-hydroxylase deficiency (11-OHD) by second-tier testing.Over a period of 5 years, screening for CAH was done in a total of 986,098 newborns by time-resolved immunoassay (DELFIA®) for 17α-hydroxyprogesterone (17-OHP). Positive samples were subsequently analyzed in an LC-MS/MS second-tier test including 17-OHP, cortisol, 11-deoxycortisol, 4-androstenedione and 21-deoxycortisol.In addition to 78 cases of 21-OHD, 5 patients with 11-OHD were identified. Diagnostic parameters were a markedly elevated concentration of 11-deoxycortisol in the presence of a low level of cortisol. Androstenedione was also increased. In contrast to 21-OHD, concentrations of 21-deoxycortisol were normal.Steroid profiling in newborn blood samples showing positive results in immunoassays for 17-OHP allows for differentiating 21-OHD from 11-OHD. This procedure may not detect all cases of 11-OHD in the newborn population because there may be samples of affected newborns with negative results for 17-OHP in the immunoassay

Efficient laser-driven proton acceleration from cylindrical and planar cryogenic hydrogen jets.

We report on recent experimental results deploying a continuous cryogenic hydrogen jet as a debris-free, renewable laser-driven source of pure proton beams generated at the 150 TW ultrashort pulse laser Draco. Efficient proton acceleration reaching cut-off energies of up to 20 MeV with particle numbers exceeding 109 particles per MeV per steradian is demonstrated, showing for the first time that the acceleration performance is comparable to solid foil targets with thicknesses in the micrometer range. Two different target geometries are presented and their proton beam deliverance characterized: cylindrical (∅ 5 μm) and planar (20 μm × 2 μm). In both cases typical Target Normal Sheath Acceleration emission patterns with exponential proton energy spectra are detected. Significantly higher proton numbers in laser-forward direction are observed when deploying the planar jet as compared to the cylindrical jet case. This is confirmed by two-dimensional Particle-in-Cell (2D3V PIC) simulations, which demonstrate that the planar jet proves favorable as its geometry leads to more optimized acceleration conditions