The meteoritic origin of Tutankhamun's iron dagger blade

Scholars have long discussed the introduction and spread of iron metallurgy in different civilizations. The sporadic use of iron has been reported in the Eastern Mediterranean area from the late Neolithic period to the Bronze Age. Despite the rare existence of smelted iron, it is generally assumed that early iron objects were produced from meteoritic iron. Nevertheless, the methods of working the metal, its use, and diffusion are contentious issues compromised by lack of detailed analysis. Since its discovery in 1925, the meteoritic origin of the iron dagger blade from the sarcophagus of the ancient Egyptian King Tutankhamun (14th C. BCE) has been the subject of debate and previous analyses yielded controversial results. We show that the composition of the blade (Fe plus 10.8 wt% Ni and 0.58 wt% Co), accurately determined through portable x‐ray fluorescence spectrometry, strongly supports its meteoritic origin. In agreement with recent results of metallographic analysis of ancient iron artifacts from Gerzeh, our study confirms that ancient Egyptians attributed great value to meteoritic iron for the production of precious objects. Moreover, the high manufacturing quality of Tutankhamun's dagger blade, in comparison with other simple‐shaped meteoritic iron artifacts, suggests a significant mastery of ironworking in Tutankhamun's time.     

Una semplice dimostrazione del teorema di bjerknes sulle circolazioni atmosferiche

Riassunto Si fa uso di una formula di derivazione di un integrale di superficie per dimostrare un teorema meteorologico diV. Bjerknes.

---

Summary Use is made of a differentiation's formula for surface integrals in showing aV. Bjerknes' meteorological theorem.

     

Modeling multiple wave systems in the eastern equatorial Pacific

Ocean Dynamics - While moderate wind and wave conditions prevail in the eastern equatorial Pacific, modeling waves in this area remains challenging due to the presence of multiple wave systems...     

Magma generation and crustal accretion as evidenced by supra-subduction ophiolites of the Albanide–Hellenide Subpelagonian zone

Abstract Ophiolites of the Mirdita–Subpelagonian zone form a nearly continuous belt in the Albanide–Hellenide orogen, including mid‐ocean ridge basalt (MORB) associations in the western Mirdita sector and supra‐subduction zone (SSZ) complexes, with prevalent island arc tholeiitic (IAT) and minor boninitic affinities in the eastern part of the belt (i.e. eastern Mirdita, Pindos, Vourinos). In addition, basalts with geochemical features intermediate between MORB and IAT (MORB/IAT) are found in the central Mirdita and in the Aspropotamos sequence (Pindos). These basalts alternate with pure MORB and are cut by boninitic dykes. The distinctive compositional characteristics of the mafic magmas parental to the different ophiolitic suites can be accounted for by partial melting of mantle sources progressively depleted by melt extractions. Partial melting processes (10–20%) of lherzolitic sources generated pure MORB, leaving clinopyroxene‐poor lherzolite as a residuum. Approximately 10% water‐assisted partial melting of this latter source, in an SSZ setting, may in turn generate basalts with MORB/IAT intermediate characteristics, whereas IAT basalts and boninites may have been derived from 10–20% and 30% partial melting, respectively, of the same source variably enriched by subduction‐derived fluids. In addition, boninites may also have been derived by comparatively lower degrees of hydrated partial melting of more refractory harzburgitic sources. A generalized petrologic model based on mass balance calculations between bulk rock and mineral compositions, indicate that most of the intrusives (from ultramafic cumulates to gabbronorites and plagiogranites), as well as sheeted dykes and volcanics (from basalts to rhyodacites) forming the bulk crustal section of the SSZ ophiolites, may be accounted for by shallow fractional crystallization from low‐Ti picritic parental magmas very similar in composition to IAT picrites from Pacific intraoceanic arcs. The most appropriate tectono‐magmatic model for the generation of the SSZ Tethyan ophiolites implies low velocity plate‐convergence of the intraoceanic subduction and generation of a nascent arc with IAT affinity and progressive slab roll‐back, mantle diapirism and extension from the arc axis to the forearc region, with generation of MORB/IAT intermediate basalts and boninitic magmas.     

Amplifying (or Reversing) the Territorial Disparities in Land Vulnerability to Soil Degradation: The Case of Italy

This article analyzes the territorial disparities in the level of land vulnerability (TDLV) to soil degradation caused by five processes (soil erosion, salinization, sealing, contamination, and compaction) as well as by climate variations in Italy in 1990 and 2000. The analysis reveals, for each soil degradation process, a typical spatial distribution across Italy. Three processes (soil salinization, compaction, and sealing) contribute significantly to the increase in land vulnerability, which is mainly concentrated in risky areas. The observed disparities highlight a growing environmental divide between northern Italy (an economically developed region, not at risk of desertification) and southern Italy and the two main islands (dry, disadvantaged regions at risk of desertification). The knowledge of such a territorial divide and of the underlying soil degradation processes is regarded as important for environmental policies at the country and regional scales aimed at sustaining the economic and socioenvironmental cohesion between areas that are either vulnerable or nonvulnerable to soil degradation. The proposed approach should be seen as part of a decision-making tool informing policies and supporting the design of management solutions, hopefully reversing disparities in land vulnerability to soil degradation.     

Climate control on stacked paleosols in the Pleistocene of the Po Basin (northern Italy)

Paleosols are recurrent features in alluvial successions and provide information about past sedimentary dynamics and climate change. Through sedimentological analysis on six sediment cores, the mud-dominated succession beneath the medieval ‘Two Towers’ of Bologna was investigated down to 100 m depth. A succession of weakly developed paleosols (Inceptisols) was identified. Four paleosols (P1, P2, P3 and PH) were radiocarbon-dated to 40–10 cal ka bp . Organic matter and CaCO₃ determinations indicate low groundwater levels during soil development, which spanned periods < 5 ka. The development and burial of soils, which occurred synchronously in the Bologna region and in other sectors of the Po Plain, are interpreted to reflect climatic and eustatic variations. Climatic oscillations, at the scale of the Bond cycles, controlled soil development and burial during Marine Isotope Stage (MIS) 3 (P1 and P2). Rapid sea-level oscillations probably induced soil development at the MIS 3/2 transition (P3) and favored burial of PH after 10 ka bp . Weakly developed paleosols in alluvial successions can provide clues to millennial-scale climatic and environmental variations. In particular, the paleosol-bearing succession of the Po Plain represents an unprecedent record of environmental changes across the Late Pleistocene (MIS 3 and 2) in the Mediterranean region.     

Multistage evolution of the European lithospheric mantle: new evidence from Sardinian peridotite xenoliths

Peridotite xenoliths entrained in Plio-Pleistocene alkali basalts from Sardinia represent fragments of the uppermost lithospheric mantle, and are characterised by an anhydrous four-phase mineral assemblage. They range in bulk rock composition from fertile spinel-lherzolites to residual spinel-harzburgites. The Sr-Nd isotope and trace element composition of clinopyroxene mineral separates varies between LREE-depleted samples with ⁸⁷Sr/⁸⁶Sr as low as 0.70262 and ¹⁴³Nd/¹⁴⁴Nd up to 0.51323 and LREE-enriched samples with ⁸⁷Sr/⁸⁶Sr up to 0.70461 and ¹⁴³Nd/¹⁴⁴Nd down to 0.51252. The available data suggest that all the studied peridotite samples suffered variable degrees of partial melting during Pre-Mesozoic times (based on Nd model ages relative to CHUR and DMM). The overprinted enrichment is related to a subsequent metasomatism, induced by fluids rising through the lithosphere that preferentially percolated the originally most depleted domains. Despite the occurrence of orogenic volcanism in the area, preferential enrichment in elements typically associated with slab derived fluids/melts (K, Rb, Sr, Th) relative to LREE has not been detected, and metasomatism seems to be more likely related to the infiltration of highly alkaline basic melts characterised by an EM-like Sr-Nd isotopic composition. Similar ⁸⁷Sr/⁸⁶Sr-¹⁴³Nd/¹⁴⁴Nd compositions, characterised by an EM signature, are observed in anorogenic mafic lavas and peridotite xenoliths from widespread localities within the "European" plate, whereas they have not previously been recorded in peridotite xenoliths and associated alkaline mafic lavas from the stable "African" lithospheric domain.     

Shell‐shape and morphometric variability in Mytilus galloprovincialis from micro‐tidal environments: responses to different hydrodynamic drivers

Tidal conditions differently influence inter‐tidal organisms in terms of general physiological and metabolic responses. In this study we investigated the morphological response in shells of Mytilus galloprovincialis native to different micro‐tidal coastal environments in the Northern Adriatic Sea. Our purpose was to highlight the ecophenotypic variability across tidal levels and to elucidate how tidal currents and waves produced by anthropogenic activities may play a part in modulating shell morphology. Three sampling sites were selected: an open‐sea area 15 km off‐shore and two sites within the lagoon of Venice, the first near one of its three inlets, and the other one in the proximity of Venice city centre. At each sampling site, organisms were seasonally collected at different depths within their vertical zonation, either in the inter‐tidal zone – i.e. at both the highest and lowest tide zonation limits, and subtidally. The mussel shells were analysed by investigation of their morphometric relationships (height/length and width/length ratios) and by elliptic Fourier analysis of the shell contours. Shell thickness and condition index were also evaluated for a better comprehension of energy allocation/partitioning. Estimates based on long‐term measurements, visual observation, wind statistics and wave growth laws allowed an evaluation of the forces acting on shells. At the open‐sea site, the observed phenotypic variability of both shell shape and thickness was clearly related to the tidal vertical zonation. At the two lagoon sites, the currents generated by tidal flow through the inlet and the waves caused by the frequent passage of boats influenced both shell shape and thickness. A trade‐off between protection and growth was apparent along the tide gradient, as emphasized by the differences in the partitioning and allocation of energy between shell and flesh production.