ALBERT

Description: The future response of the Antarctic ice sheet to rising temperatures remains highly uncertain. A useful period for assessing the sensitivity of Antarctica to warming is the Last Interglacial (LIG) (129 to 116 ky), which experienced warmer polar temperatures and higher global mean sea level (GMSL) (+6 to 9 m) relative to present day. LIG sea level cannot be fully explained by Greenland Ice Sheet melt (∼2 m), ocean thermal expansion, and melting mountain glaciers (∼1 m), suggesting substantial Antarctic mass loss was initiated by warming of Southern Ocean waters, resulting from a weakening Atlantic meridional overturning circulation in response to North Atlantic surface freshening. Here, we report a blue-ice record of ice sheet and environmental change from the Weddell Sea Embayment at the periphery of the marine-based West Antarctic Ice Sheet (WAIS), which is underlain by major methane hydrate reserves. Constrained by a widespread volcanic horizon and supported by ancient microbial DNA analyses, we provide evidence for substantial mass loss across the Weddell Sea Embayment during the LIG, most likely driven by ocean warming and associated with destabilization of subglacial hydrates. Ice sheet modeling supports this interpretation and suggests that millennial-scale warming of the Southern Ocean could have triggered a multimeter rise in global sea levels. Our data indicate that Antarctica is highly vulnerable to projected increases in ocean temperatures and may drive ice–climate feedbacks that further amplify warming.

Description: Aus dem indo-australischen Archipel sind die folgenden Arten von Atherina genannt oder beschrieben: 1. A. argyrotaenia Blkr. 2. A. bimanensis Blkr. 3. A. brachypterus Blkr. 4. A. cylindrica C. V. 5. A. duodecimals C. V. 6. A. eendrachtensis Q. G. 7. A. forsk\xc3\xa5li R\xc3\xbcpp. 8. A. japonica Blkr. 9. A. lacunosa Forst. 10. A. pinguis Lac. 11. A. temmincki Blkr. 12. A. waigiensis Q. G. 13. A. valenciennesi Blkr.\nHinsichtlich vieler von diesen Arten herrscht grosse Verwirrung, was nicht verwundern kann bei der oft sehr ungen\xc3\xbcgenden Beschreibung, die vor allem in der \xc3\xa4lteren Literatur derart ist, dass daraus unm\xc3\xb6glich eine Art wiedererkannt werden kann. So kommt es, dass viele Arten ihr Bestehen aus der einen Publikation in eine folgende fortschleppen ohne dass die Autoren viel Kritik anwandten oder, so weit dies m\xc3\xb6glich ist, sich die M\xc3\xbche gaben die typischen Arten in den Museen zu untersuchen.\nMit Freude musste man daher das vor kurzem erschienene Werk von D. St. Jordan und C. L. Hubbs \xe2\x80\x9eA Monographic Review of the family of Atherinidae" 1) begr\xc3\xbcssen. Aber leider gibt es keine Antwort auf die

Description: 1. ABOUT THE NOMENCLATURE OF THE SPECIES OF FISTULARIA.\nThe species of Fistularia have caused much trouble and misunderstanding as to their proper names.\nFormerly there were 2 species known, in G\xc3\xbcnther\'s Catalogue 2) distinguished as F. tabaccaria L. and F. serrata Cuv.\nF. tabaccaria is restricted to the tropical Atlantic and easily distinguished by the upper lateral edge of the snout (formed by the prefrontal and metapterygoid) which is nearly smooth, being only slightly crenulated in the adult, and by the blue spots and stripes on the upper parts of head and body.\nF. serrata Cuv. is immaculate, the upper lateral edge of the snout sharply serrated and its habitat in all tropical seas.\nIn 1880 G\xc3\xbcnther 3) found, that his F. serrata Cuv. contained two different species, which he separated on the following characters: \xe2\x80\x9eInterorbital space concave: the two middle ridges on the upper surface of the snout, run close and parallel to each other along the anterior half of the length of the snout. Body moderately depressed with minute asperities, which render the skin rough to the touch". F. serrata. \xe2\x80\x9eBones of the head less deeply sculptured than in Fistularia serrata, but with the upper lateral edges of the snout likewise serrated. Interorbital space nearly flat. The two middle ridges on the upper surface of the snout are not very close together, and diverge again on the anterior half of the length of the snout, converging finally on the foremost part.\nBody much depressed, nearly smooth, the asperities of the skin being scarcely perceptible". . . . . . . . . . . . . . F. depressa.

Description: The SWATH‐D experiment involved the deployment of a dense temporary broadband seismic network in the Eastern Alps. Its primary purpose was enhanced seismic imaging of the crust and crust–mantle transition, as well as improved constraints on local event locations and focal mechanisms in a complex part of the Alpine orogen. The study region is a key area of the Alps, where European crust in the north is juxtaposed and partially interwoven with Adriatic crust in the south, and a significant jump in the Moho depth was observed by the 2002 TRANSALP north–south profile. Here, a flip in subduction polarity has been suggested to occur. This dense network encompasses 163 stations and complements the larger‐scale sparser AlpArray seismic network. The nominal station spacing in SWATH‐D is 15 km in a high alpine, yet densely populated and industrialized region. We present here the challenges resulting from operating a large broadband network under these conditions and summarize how we addressed them, including the way we planned, deployed, maintained, and operated the stations in the field. Finally, we present some recommendations based on our experiences.

Description: In this study, we analyzed a large seismological dataset from temporary and permanent networks in the southern and eastern Alps to establish high-precision hypocenters and 1-D VP and VP/VS models. The waveform data of a subset of local earthquakes with magnitudes in the range of 1–4.2 ML were recorded by the dense, temporary SWATH-D network and selected stations of the AlpArray network between September 2017 and the end of 2018. The first arrival times of P and S waves of earthquakes are determined by a semi-automatic procedure. We applied a Markov chain Monte Carlo inversion method to simultaneously calculate robust hypocenters, a 1-D velocity model, and station corrections without prior assumptions, such as initial velocity models or earthquake locations. A further advantage of this method is the derivation of the model parameter uncertainties and noise levels of the data. The precision estimates of the localization procedure is checked by inverting a synthetic travel time dataset from a complex 3-D velocity model and by using the real stations and earthquakes geometry. The location accuracy is further investigated by a quarry blast test. The average uncertainties of the locations of the earthquakes are below 500 m in their epicenter and ∼ 1.7 km in depth. The earthquake distribution reveals seismicity in the upper crust (0–20 km), which is characterized by pronounced clusters along the Alpine frontal thrust, e.g., the Friuli-Venetia (FV) region, the Giudicarie–Lessini (GL) and Schio-Vicenza domains, the Austroalpine nappes, and the Inntal area. Some seismicity also occurs along the Periadriatic Fault. The general pattern of seismicity reflects head-on convergence of the Adriatic indenter with the Alpine orogenic crust. The seismicity in the FV and GL regions is deeper than the modeled frontal thrusts, which we interpret as indication for southward propagation of the southern Alpine deformation front (blind thrusts).

Description: In this study, 3-D models of P-wave velocity (Vp) and P- and S-wave ratio (Vp/Vs) of the crust and upper mantle in the Eastern and eastern Southern Alps (northern Italy and southern Austria) were calculated using local earthquake tomography (LET). The dataset includes high-quality arrival-times from well-constrained hypocenters observed by the dense, temporary seismic networks of the AlpArray AASN and SWATH-D. The resolution of the LET was checked by synthetic tests and analysis of the Model Resolution Matrix. The small inter-station spacing (average of ∼15 km within the SWATH-D network) allowed us to image crustal structure at unprecedented resolution across a key part of the Alps. The derived P velocity model revealed a highly heterogeneous crustal structure in the target area. One of the main findings is that the lower crust is thickened, forming a bulge at 30-50 km depth just south of and beneath the Periadriatic Fault and the Tauern Window. This indicates that the lower crust decoupled both from its mantle substratum as well as from its upper crust. The Moho, taken to be the iso-velocity contour of Vp=7.25 km/s, agrees with the Moho depth from previous studies in the European and Adriatic forelands. It is shallower on the Adriatic side than on the European side. This is interpreted to indicate that the European Plate subducted beneath the Adriatic Plate in the Eastern and eastern Southern Alps.

Description: We demonstrate the capability of distributed acoustic sensing (DAS) to record volcano-related dynamic strain at Etna (Italy). In summer 2019, we gathered DAS measurements from a 1.5 km long fibre in a shallow trench and seismic records from a conventional dense array comprised of 26 broadband sensors that was deployed in Piano delle Concazze close to the summit area. Etna activity during the acquisition period gives the extraordinary opportunity to record dynamic strain changes (∼ 10−8 strain) in correspondence with volcanic events. To validate the DAS strain measurements, we explore array-derived methods to estimate strain changes from the seismic signals and to compare with strain DAS signals. A general good agreement is found between array-derived strain and DAS measurements along the fibre optic cable. Short wavelength discrepancies correspond with fault zones, showing the potential of DAS for mapping local perturbations of the strain field and thus site effect due to small-scale heterogeneities in volcanic settings.

Description: The 250 km long profile 3B/MVE (East) was recorded in 1990 as part of the joint seismic reflection venture DEKORP 1990-3/MVE (Muenchberg-Vogtland-Erzgebirge) between the two former German Republics shortly before their unification. The aim of DEKORP 1990-3/MVE was to explore the structure of the crust from the Rhenish Shield through the Bohemian Massif to the Ore Mountains. The entire profile consists of DEKORP 3A, DEKORP 3B/MVE (West) and its prolongation to the east DEKORP 3B/MVE (East). Its total length amounts to about 600 km. 24 short seismic cross lines and associated 3D blocks with single fold coverage were also recorded. The seismic survey of 3B/MVE (East) was conducted to investigate the deep crustal structure of the Saxothuringian Zone of the Central European Variscian Belt along the northern margin of the Bohemian Massif with high-fold near-vertical incidence vibroseis acquisition. The main objectives were to image the deep structures of the Muenchberg Gneiss Complex, to concern the volume of Variscan granites by combining seismic and gravity data as well as to determine the origin and nature of the deep regional NW-trending fault systems. Details of the experiment, preliminary results and interpretations were published by DEKORP Research Group (B) et al. (1994) and Förste, Lück & Schulze (1994). The Technical Report of DEKORP 3B/MVE (East) gives complete information about acquisition and processing parameters. The European Variscides, extending from the French Central Massif to the East European Platform, originated during the collision between Gondwana and Baltica in the Late Palaeozoic. Due to involvement of various crustal blocks in the orogenesis, the mountain belt is subdivided into distinct zones. The external fold-and-thrust belts of the Rhenohercynian and Saxothuringian as well as the predominantly crystalline body of the Moldanubian dominate the central European segment of the Variscides. Polyphase tectonic deformation, magmatism and metamorphic processes led to a complex interlinking between the units. The 3B/MVE (East) line runs in SW-NE direction along the southern margin of the Saxothuringian belt from the Franconian Line, the southwestern boundary fault zone of the Bohemian Massif, to the Lausitz Massif. It traverses the allochthonous Muenchberg Gneiss Complex, the Cambro-Ordovician South Vogtland Syncline Zone, the Eibenstock-Karlovy Vary Granite Complex as well as the Ore Mountains crystalline blocks, the most significant Bouguer gravity low in Central Europe. Besides, the line intersects several NW-fault systems such as the Floeha Zone fault system and the Mid Saxon fault (DEKORP Research Group (B) et al., 1994). The line 3B/MVE (East) is complemented by eight short cross lines. To the west the profile is extended by DEKORP 3B/MVE (West). In the Muenchberg Gneiss Complex the 3B/MVE (East) profile is crossed by DEKORP 4N, which runs parallel to the western border of the Bohemian Massif near the KTB drilling site. Farther to the east the line has an intersection with DEKORP 9501 (GRANU).

Description: The 187 km long line 4N was recorded in 1985 as part of the DEKORP project, the German continental seismic reflection program, and served as a basis for a network of six seismic reflection lines KTB 8501 – 8506, which were performed to investigate the planned target area for the Continental Deep Drilling Program (KTB) in the Upper Palatinate. The aim of the survey 4N was to explore the crustal structure of the central Mid-European Variscides down to the Moho and the uppermost mantle with high-fold near-vertical incidence vibroseis acquisition and, in particular, to scan the suture between the Moldanubian Zone and the northward adjacent Saxothuringian Zone. Details of the experiment, first results and interpretations were published by DEKORP Research Group (1987, 1988). The Technical Report of line 4N gives complete information about acquisition and processing parameters. The European Variscides, extending from the French Central Massif to the East European Platform, originated during the collision between Gondwana and Baltica in the Late Palaeozoic. Due to involvement of various crustal blocks in the orogenesis, the mountain belt is subdivided into distinct zones. The external fold-and-thrust belts of the Rhenohercynian and Saxothuringian as well as the predominantly crystalline body of the Moldanubian dominate the central European segment of the Variscides. Polyphase tectonic deformation, magmatism and metamorphic processes led to a complex interlinking between the units. The Saxothuringian represents the infill of a Cambro-Ordovician basin. The Moldanubian contains blocks of pre-Variscan crust and their Palaezoic cover. During the Variscan orogeny the Moldanubian crust was thrust towards the NW over the Saxothuringian foreland. Both units were welded together by a low-pressure metamorphism accompanied by polyphase deformation (DEKORP Research Group, 1987, 1988). The SE-NW striking line 4N runs along the western border of the Bohemian Massif perpendicular to the main tectonic trend (SW-NE). The profile starts in the Bavarian Forest and runs across the Upper Palatinate Forest. Shortly before the NE-trending Erbendorf Line, which separates the Moldanubian unit from the Saxothuringian unit, the profile runs through the area of the KTB drill site. In the Saxothuringian DEKORP 4N runs through the Fichtel Mountains, the Muenchberg Gneiss Complex and ends in the Franconian Forest. In the Bavarian Forest the line 4N traverses DEKORP 4Q nearly perpendicularly. Farther northwest the profile crosses KTB 8501 – 8503, which were arranged parallel to strike of the orogenic belt, as well as the DEKORP 3-D survey ISO 1989 around the KTB drill hole. In the Muenchberg Gneiss Complex the 4N profile is intersected by DEKORP 3B/MVE (East), which runs along the southern margin of the Saxothuringian belt in a SW-NE direction.