Primitive Signature Research Articles

Locally verifiable approximate multi-member quantum threshold aggregation digital signature scheme

Locally verifiable aggregate signature primitives can reduce the complexity of aggregate signature verification by computing locally open algorithms to generate auxiliary parameters. However, the breakthrough results of quantum computers at this stage indicate that it will be possible for quantum computers to break through the security of traditional hardness-based aggregated signature schemes. In order to solve the above problems, this paper proposes for the first time a new locally verifiable class of multi-member quantum threshold aggregated digital signature scheme based on the property that the verification of quantum coset states is a projection on the trans-subspace. Combined with the idea of auxiliary parameter generation in traditional locally verifiable aggregated signatures, it makes the current stage of threshold quantum digital signatures realize the aggregated features, and reduces the complexity of the verification of aggregated signatures while realizing post-quantum security. In addition, the verification of the signature key (quantum state) of the signature members does not require measurement operations, and the generated signatures are classical, so the communication between the trusted third center (TC), the set of signature members, the classical digital signature verifier (CV), and the third-party trusted aggregation generator (TA) are all classical, simplifying the communication model. In the performance analysis we make this quantum aggregation signature scheme more flexible as well as less quantum state preparation compared to other schemes.

A Secure Interoperability Management Scheme for Cross-Blockchain Transactions

Blockchain technology has recently attracted tremendous interest due to its potential to revolutionize the industry by achieving decentralization while increasing the number of data sources, transparency, reliability, auditability, and trustworthiness. However, one of the major barriers to the widespread adoption of blockchain applications is the lack of mutual consensus and management across blockchains. Cross-blockchain consensus refers to one blockchain network reaching a consensus with another blockchain network to provide the ability to interact and share data. In this paper, we propose a secure management scheme with symmetric cross-blockchain communication and certificateless signature primitives, in which two heterogeneous blockchains are linked by a relay chain to simultaneously deliver cross-blockchain transaction security, achieve compatibility among various blockchains, and ensure the consistency of data exchanged, in practice. Additionally, our evaluation and security analysis shows the practicability and security of our proposed management scheme and demonstrates that a common test platform based on Ethereum can achieve acceptable computation costs.

Unravelling the hidden evidences of magma mixing processes via combination of in situ Sr isotopes and trace elements analyses on plagioclase crystals

Granites from the ~580 Ma oxidized A-type Salto Rapakivi Granite (Itu Granitic Province, SE Brazil) bear abundant felsic microgranular enclaves (FMEs) and scarce cm-sized mafic microgranular enclaves (MMEs) with whole-rock Sr and Nd isotope signatures identical to those of their host rapakivi granites. In order to unravel the sources involved in the formation of both enclave types we conducted in situ trace elements and Sr isotopic analyses on plagioclase megacrysts from representative rocks of rapakivi granites, porphyry granites and both microgranular enclave varieties. Plagioclase from host rapakivi granites have 87Sr/86Sr ~0.7068, and are relatively more radiogenic than those from the enclaves. Plagioclase xenocrysts from the FMEs typically register a rimward decrease in 87Sr/86Sr ratios, with core 87Sr/86Sr up to 0.7069, whereas rims are usually in equilibrium with whole rock (~0.7060–0.7063). Crystals with U-shaped Sr isotopes profiles (less radiogenic cores with rimward increase in 87Sr/86Sr ratios) are rare, as are crystals with strongly radiogenic signatures observed in partially digested xenoliths found within the enclaves (87Sr/86Sr ~0.709–0.710). Plagioclase from MMEs show more primitive signatures (87Sr/86Sr 0.7055–0.7058). Crystals from the MMEs are distinguished by higher Sr (~1000 ppm) and lower Eu (< 0.5 ppm) and light rare earth elements (LREE, 6–12 ppm) compared to crystals from FMEs, porphyry and granite, which have Sr = 200–600 ppm, and LREE = 20–80 ppm. Our results allowed us to infer that FMEs were formed by mixing between a resident melt similar to that of rapakivi granites with a less radiogenic melt similar to that which originated the MMEs. Therefore the combined use of Sr isotopes and trace element contents in plagioclase crystals from A-type granites might shed light on the sources of rock varieties that have similar whole-rock isotope signatures.

A post-quantum digital signature scheme on groups with four-dimensional cyclicity

Introduction: Development of practical post-quantum signature schemes is a current challenge in the applied cryptography. Recently, several different forms of the hidden discrete logarithm problem were proposed as primitive signature schemes resistant to quantum attacks. Purpose: Development of a new form of the hidden discrete logarithm problem set in finite commutative groups possessing multi-dimensional cyclicity, and a method for designing post-quantum signature schemes. Results: A new form of the hidden discrete logarithm problem is introduced as the base primitive of practical post-quantum digital signature algorithms. Two new four-dimensional finite commutative associative algebras have been proposed as algebraic support for the introduced computationally complex problem. A method for designing signature schemes on the base of the latter problem is developed. The method consists in using a doubled public key and two similar equations for the verification of the same signature. To generate a pair of public keys, two secret minimum generator systems &lt;G, Q&gt; and &lt;H, V&gt; of two different finite groups G&lt;G, Q&gt; and G&lt;H, V&gt; possessing two-dimensional cyclicity are selected at random. The first public key (Y, Z, U) is computed as follows: Y = Gy1Qy2a, Z = Gz1Qz2b, U = Gu1Qu2g, where the set of integers (y1, y2, a, z1, z2, b, u1, u2, g) is a private key. The second public key (Y¢, Z¢, U¢) is computed as follows: Y¢ = Hy1Vy2a, Z¢ = Hz1Vz2b, U¢ = Hu1Vu2g. Using the same parameters to calculate the corresponding elements belonging to different public keys makes it possible to calculate a single signature which satisfies two similar verification equations specified in different finite commutative associative algebras. Practical relevance: Due to a smaller size of the public key, private key and signature, as well as approximately equal performance as compared to the known analogues, the proposed digital signature scheme can be used in the development of post-quantum signature algorithms.

Burying Earth's Primitive Mantle in the Slab Graveyard

AbstractThe evolution of mantle composition can be viewed as a process of destruction whereby the initial chemical state is overprinted and reworked with time. Analyses of ocean island basalts reveals that some portion of the mantle has survived this process, retaining a chemically “primitive” signature. A question that remains is how this primitive signature has survived four and a half billion years of vigorous convection. We hypothesize that some of Earth's primitive mantle is buried within a slab graveyard at the core‐mantle boundary. We explore this possibility using high‐resolution finite element models of mantle convection, in which oceanic lithosphere is produced at zones of plate spreading and subducted at zones of plate convergence. Upon subduction, dense oceanic crust sinks to the base of the mantle and gradually accumulates to form broad, robust thermochemical piles. Sinking oceanic crust entrains the surrounding mantle whose composition is predominantly primitive early in the model's evolution. As a result, thermochemical piles are initially supplied with relatively high concentrations of primitive material—summing up to ∼30% their total mass. The dense oceanic crust dominating the piles resists efficient mixing and preserves the primitive material that it is intermingled with. The significance of this process is shown to be proportional the rate of mantle processing through time and the excess density of oceanic crust at mantle pressures and temperatures. Unlike other theories for the survival of Earth's primitive mantle, this one does not require the early Earth to have large‐scale domains of anomalously high density and/or viscosity.

Biological and therapeutic implications of a unique subtype of NPM1 mutated AML

In acute myeloid leukemia (AML), molecular heterogeneity across patients constitutes a major challenge for prognosis and therapy. AML with NPM1 mutation is a distinct genetic entity in the revised World Health Organization classification. However, differing patterns of co-mutation and response to therapy within this group necessitate further stratification. Here we report two distinct subtypes within NPM1 mutated AML patients, which we label as primitive and committed based on the respective presence or absence of a stem cell signature. Using gene expression (RNA-seq), epigenomic (ATAC-seq) and immunophenotyping (CyToF) analysis, we associate each subtype with specific molecular characteristics, disease differentiation state and patient survival. Using ex vivo drug sensitivity profiling, we show a differential drug response of the subtypes to specific kinase inhibitors, irrespective of the FLT3-ITD status. Differential drug responses of the primitive and committed subtype are validated in an independent AML cohort. Our results highlight heterogeneity among NPM1 mutated AML patient samples based on stemness and suggest that the addition of kinase inhibitors to the treatment of cases with the primitive signature, lacking FLT3-ITD, could have therapeutic benefit.

Evidence for primitive magma storage and eruption following prolonged equilibration in thickened crust

In continental arcs, the exposure of primitive eruptive products at the surface is typically a result of rapid magmatic transfer through the crust. As a result, the initially primitive magma experiences minimal crustal residence and thus insignificant differentiation towards more evolved products. This rapid transfer of primitive magma through thickened crust is commonly recorded from smaller, monogenetic cinder cones. Manantial Pelado (35.5° S) is a long-lived stratocone in the Southern Andean Volcanic Zone (SVZ) overlying thick continental crust (45–50 km) that produces almost exclusively mafic material. As Manantial Pelado is surrounded by extensive silicic volcanism, the study of its mafic exposure as a stratocone can be used to further understand magmatic origins of long-lived volcanic systems. Our study uses textural, geochemical, and geochronological data from lavas collected from Manantial Pelado to characterize its magmatic petrogenesis, assess the primitive nature, and explain processes in the crust within the SVZ. A geologic description of the volcano reveals a mostly monotonous eruptive history of basaltic andesites that are now accessible through glacially carved valleys. New 40Ar/39Ar dating constrains most of the volcano’s cone constructing phase to last from ~ 220 to 190 ka. At ~ 30 ka, small-volume activity and different petrography of more intermediate magmas were present reflecting a change in the volcano’s character. A combination of the whole-rock and mineral-scale data reveals that basaltic andesites at Manantial Pelado are among the most primitive magmas in the thickened crust of the SVZ. Evidence for this primitive signature consists of textural and zonation patterns in olivine, the presence of Cr-spinel in olivine cores, and elevated Fo and Ni content within olivine cores. This data combined with elemental diffusion modeling provides evidence for a primitive signature for these lavas. Intermediate Fo olivines with uniform core compositions (Fo80–84) suggest that basaltic andesites reside in the crust in quasi-closed system environments for extended storage prior to eruption (~ 25–6000 years). Diffusive equilibration in those intermediate Fo olivines masks the primitive nature of the magmas. These results suggest that mafic magmas can have a protracted storage history in the crust that does not significantly alter their primitive bulk composition before reaching the surface. We argue that these are important processes in understanding the magmatic origin of long-lived systems and the presence of compositionally homogenous olivines at intermediate Fo content may represent cryptic evidence for recharge with primitive magmas that experienced prolonged crustal storage.

The transcriptional profile analysis of bone marrow-derived CD34+ stem cell in diabetic patients reveals a primitive signature of their dysfunction

The transcriptional profile analysis of bone marrow-derived CD34+ stem cell in diabetic patients reveals a primitive signature of their dysfunction

Formation of rapakivi feldspar in the Deer Isle Granite Complex, coastal Maine: in situ lead isotope and trace-element analysis

Rapakivi and alkali feldspar phenocrysts from the Devonian Deer Isle Granite Complex, Maine were investigated to see if magma mixing or isothermal decompression was responsible for their formation. Pb-isotope and trace-element analyses of alkali feldspar ovoids and their plagioclase inclusions were obtained by LA-ICP-MS to determine the characteristics of the initial magma; these were compared with the plagioclase mantles. Rapakivi grains show a decrease in Pb-isotopic values and an increase in Ba, La, and Ce concentrations from the ovoids and inclusions to the innermost plagioclase mantles adjacent to the ovoids. These variations, along with CL imagery of quartz phenocrysts, indicate an open system with compositional changes in the magma chamber occurring during rapakivi feldspar growth. Repeated episodes of magma mixing/replenishment by Ba and LREE enriched magmas with lower Pb-isotopic ratios (along with hybridized variations with the host magma) created localized dissolution of alkali feldspar and quartz. Alkali feldspar phenocrysts proximal to these zones of thermal perturbation were first resorbed and then mantled by plagioclase that records the more primitive signature of the more mafic melt. Pb-isotopic values and Ba, La, and Ce concentrations trend back to the initial magma composition at the mantle rims as the effects of the mixing event dissipated. For grains that were somewhat more distal to these zones of mixing, resorption of the alkali feldspar crystals did not occur, yet the fresh supply of Ba resulted in Ba-rich alkali feldspar mantles over Ba-poor alkali feldspar cores. Other alkali feldspar crystals were too far from the site of mixing; hence, they lack any evidence of open system crystallization. As crystallization of the chamber continued along solidification fronts, batches of cooler crystal-rich magmas settled en masse to the floor. Disaggregation of these batches during settling, and subsequent accumulation on the reservoir floor, brought grains with disparate crystallization histories together. Filter pressing of the cumulate pile flushed highly evolved melts/fluids out from interstitial pores to the high silica, upper portions of the chamber. The crystallization, transportation, and juxtaposition of disparate types of feldspar phenocrysts suggest that a relatively large and active magma chamber, periodically recharged by localized batches of melt, must have existed. In this case, it is clear that rapakivi mantled feldspars are the result of magma mixing; such interpretations may apply to many other occurrences as well.

Delegatable functional signatures

The authors introduce delegatable functional signatures (DFS) which support the delegation of signing capabilities to another party, called the evaluator, with respect to a functionality . In a DFS, the signer of a message can choose an evaluator, specify how the evaluator can modify the signature without voiding its validity, allow additional input, and decide how the evaluator can further delegate its capabilities. Technically, DFS unify several seemingly different signature primitives, including functional signatures and policy-based signatures, sanitisable signatures, identity-based signatures, and blind signatures. The authors characterise the instantiability of DFS with respect to the corresponding security notions of unforgeability and privacy. On the positive side, they show that privacy-free DFS can be constructed from one-way functions. Furthermore, they show that unforgeable and private DFS can be constructed from doubly-enhanced trapdoor permutations. On the negative side, they show that the previous result is optimal regarding its underlying assumptions. Their impossibility result shows that unforgeable private DFS cannot be constructed from one-way permutations.

Data Lineage in Malicious Environments

Intentional or unintentional leakage of confidential data is undoubtedly one of the most severe security threats that organizations face in the digital era. The threat now extends to our personal lives: a plethora of personal information is available to social networks and smartphone providers and is indirectly transferred to untrustworthy third party and fourth party applications. In this work, we present a generic data lineage framework Lime for data flow across multiple entities that take two characteristic, principal roles (i.e., owner and consumer). We define the exact security guarantees required by such a data lineage mechanism toward identification of a guilty entity, and identify the simplifying non-repudiation and honesty assumptions. We then develop and analyze a novel accountable data transfer protocol between two entities within a malicious environment by building upon oblivious transfer, robust watermarking, and signature primitives. Finally, we perform an experimental evaluation to demonstrate the practicality of our protocol and apply our framework to the important data leakage scenarios of data outsourcing and social networks. In general, we consider Lime , our lineage framework for data transfer, to be an key step towards achieving accountability by design .

Hematopoietic Stem Cell Mobilization for Gene Therapy: The Combination of G-CSF+Plerixafor in Patients with Beta-Thalassemia Major Provides High Yields of CD34+ Cells with Primitive Signatures

Hematopoietic stem cell engineering is a promising therapy to cure b-thalassemia, in particular for patients who lack a suitable BM donor for allogeneic transplantation. Since the engrafted gene-corrected stem cells will not have any selective advantage over the unmodified ones, the effectiveness of the therapy in this setting largely depends on the infusion of high numbers of gene-modified cells and on the conditioning regimen. The quality of the infused cells is also crucial for the clinical outcome and the duration of the therapeutic effect.HSPCs mobilization, particularly when G-CSF and plerixafor are used in combination, has been proved to be the optimal approach to harvest a large number of CD34+cells in patients with hematological malignancies and in healthy volunteers. However adult heavily-transfused thalassemia patients have intrinsic characteristics that may adversely affect both the safety and the efficacy of mobilization.We conducted a clinical trial to investigate the safety and effectiveness of mobilizing HSPCs with G-CSF+plerixafor in adult patients affected by β-thalassemia major with the aim to reach a cell dose of ≥8x106 CD34+cells/Kg. We studied the kinetic of CD34+cells during mobilization and performed a comprehensive characterization of their molecular and functional properties.All patients completed the mobilization according to the protocol (G-CSF 10 μg/kg/day for four days, followed by plerixafor 240 μg/kg in the evening on day 4) and no serious adverse events occurred. Leukapheresis was done 10-12 hours after plerixafor (on day 5). Three of the four patients reached the target cell dose or more in single-apheresis collections, even one patient where a significant dose reduction of G-CSF was halved due to early hyperleukocytosis. For one patients the number of cells collected in the first apheresis was slightly below the established target and therefore, according to the protocol, she was subjected to a second apheresis on day 6, after an additional dose of plerixafor. The total yield from the combined apheresis in this patient was 13.0 CD34+cells /Kg. CD34+ cell yields per single apheresis in our patients were comparable to those in healthy donors (12 pts) mobilized in our hospital with G-CSF alone.A significant increase in the mean peripheral blood CD34+ cells (12.1± 8.2 fold), was unanimously observed after plerixafor addiction. The frequencies of the more primitive CD34+cell subtypes (CD34+CD38- and CD34+CD38-133+) as well as the clonogenic capacity tested in short term in vitro assay were found significantly increased too.Comprehensive microarray analysis of genes expressed in the CD34+ cells purified from the same patient upon mobilization with G-CSF alone (G/CD34+cell) and with G-CSF+plerixafor (G+pl/CD34+cell) highlighted a different HSCs repertoire.According to the mechanism of plerixafor mobilization, CXCR-4 gene expression was found 5-fold higher in G+pl/CD34+cells. CXCR-4 gene is known to be expressed on the surface of more primitive CD34+ HSCs with long-term repopulating potential and plays a central role in the regulation of adhesion of them to native niche in the BM.A substantial number of genes with previously shown implication in mechanisms of homing and engraftment (CXCR4, CD82, DPP4, ROBO4), or genes linked to stress resistance (CXCL4, SOD2, IL8, PPBP) as well as several chemokines genes involved in cell mobility (CXCL2, CXC3, CXCR2) were also found to be up-regulated in G+pl/CD34+cells.Overall, the yields, the primitive signatures of CD34+cells indicate the G-CSF+plerixafor mobilized peripheral blood as optimal graft that should favor HSPCs engraftment after transplantation. This findings has therapeutic implications not only for b-thalassemia but also for other hematopoietic stem cell gene therapy applications. This work was funded by the F and P Cutino Foundation - Project RiMedRi CUP G73F1200015000. DisclosuresNo relevant conflicts of interest to declare.

Missing lead and high ³He/⁴He in ancient sulfides associated with continental crust formation.

Major terrestrial reservoirs have Pb isotopes more radiogenic than the bulk silicate Earth. This requires a missing unradiogenic Pb reservoir, which has been argued to reside in the lower continental crust or dissolved in the core. Chalcophile element studies indicate that continent formation requires the formation of sulfide-bearing mafic cumulates in arcs. Because Pb, but not U, partitions into sulfides, we show that continent formation must have simultaneously generated time-integrated unradiogenic Pb reservoirs composed of sulfide-bearing cumulates, now recycled back into the mantle or stored deep in the continental lithosphere. The generation of such cumulates could also lead to coupled He-Pb isotopic systematics because 4He is also produced during U-Th-Pb decay. Here, we show that He may be soluble in sulfide melts, such that sulfide-bearing cumulates would be enriched in both Pb and He relative to U and Th, “freezing” in He and Pb isotopes of the ambient mantle at the time of sulfide formation. This implies that ancient sulfide-bearing cumulates would be characterized by unradiogenic Pb and He isotopes (high-3He/4He). These primitive signatures are usually attributed to primordial, undifferentiated mantle, but in this case, they are the very imprint of mantle differentiation via continent formation.

A non-primitive origin of near-chondritic S–Se–Te ratios in mantle peridotites; implications for the Earthʼs late accretionary history

The chalcophile and highly siderophile elements Se and Te, like the other Highly Siderophile Elements (HSE) in the terrestrial mantle, may constitute powerful key tracers for meteoritic materials that hit the Earth in its latest accretionary stages (“Late Veneer”). Here the Se and Te systematics of mantle-derived peridotites (orogenic peridotites, ophiolites, cratonic peridotite xenoliths) are assessed. Combined with published in-situ analyses of HSE host minerals, whole-rock data are modelled with respect to current petrogenetic models that affect mantle composition, for example partial melting and magmatic refertilisation. We demonstrate that the near-chondritic Se/Te signature (SeN/TeN≈9±4; N = CI-chondrite normalised) of “fertile” ophiolitic and orogenic lherzolites cannot be a primitive signature of the Earthʼs mantle. This signature can however be explained by simple refertilisation models. The HSE–Se–Te budget of these fertile rocks can be modelled by mixing various proportions of a residual assemblage of Fe–Ni monosulphide solid solutions (Mss) and/or refractory platinum group minerals (PGMs – Ru–Os–Ir sulphides + Pt–Ir–Os alloys) with a metasomatic assemblage comprising low-temperature Pt–Pd–Te phases and Cu–Ni-rich sulphides. On the other hand, the reported Se and Te ratios in fertile peridotites are not consistent with melt depletion alone. Additions of late-stage metasomatic S–Se–Te–HSE-rich phases render Primitive Upper Mantle (PUM) estimates for Se and Te highly debatable, especially without appropriate consideration of refertilisation and metasomatism. Our results indicate that there is currently no firm evidence for chondritic S–Se–Te signatures in the Primitive Upper Mantle. This conclusion challenges the simplistic perception that near-chondritic Se/Te ratios may readily trace the Late Veneer composition.

A deep mantle origin for the primitive signature of ocean island basalt

Seismic data have identified large-scale compositional heterogeneities in Earth’s deep mantle, but their origin is debated. Numerical modelling demonstrates that seismological and geochemical constraints on the character of these heterogeneities can be satisfied if they are composed of primitive material formed early in Earth’s history.

Reply to comment by C. Pin and J. Rodríguez on “Rheic Ocean ophiolitic remnants in southern Iberia questioned by SHRIMP U‐Pb zircon ages on the Beja‐Acebuches amphibolites”

Reply to comment by C. Pin and J. Rodríguez on “Rheic Ocean ophiolitic remnants in southern Iberia questioned by SHRIMP U‐Pb zircon ages on the Beja‐Acebuches amphibolites”

Through-the-Wall SAR Attributed Scattering Center Feature Estimation

We consider characterization of building interior structure from two-pass interferometric circular synthetic aperture radar data. We model returns from complex building structures as the sum of the responses from scattering primitives-plates, dihedrals, and trihedrals-observed through transfer functions that characterize both the transmission through and reflection from dielectric surfaces. Maximum-likelihood estimates for the location of primitive features and wall propagation/reflection parameters are obtained through a two-stage detection-and-estimation algorithm. We employ a sparse reconstruction algorithm to detect primitive signatures in the presence of wall effects and refine our estimates using a nonlinear minimization of local cost functions. We show that using simplified wall and primitive models, we can extract geometrically relevant features which can be combined to reveal 3-D floorplan estimates of buildings. Examples illustrate the effectiveness of the feature extraction approach.

Coexisting calc-alkaline and ultrapotassic magmatism at Monti Ernici, Mid Latina Valley (Latium, central Italy)

New major and trace element data, and Sr-Nd-Pb-O isotopic ratios for volcanic mafic rocks outcropping at Monti Ernici in the Mid Latina Valley (southern Latium) are reported, with the aim of investigating the nature and evolution of Plio-Quaternary K-rich volcanism in Central Italy. Petrographical and geochemical studies allow us to identify mafic rocks ranging from ultrapotassic (HKS) to shoshonitic (SHO), and calc-alkaline (CA), these last ones being identified for the first time. The CA rocks exhibit the most primitive signatures for Sr, Nd, and Pb isotopes ( 87 Sr/ 86 Sr =0.706326–0.706654; 143 Nd/ 144 Nd = 0.512388–0.512361; 206 Pb/ 204 Pb = 18.944–18.940). The δ 18 O values are variable (δ 18 O cpx from +5.75 to +7.08 ‰; and δ 18 O ol from +5.50 to +6.23 ‰), suggesting interaction with carbonate wall rocks. Radiogenic isotope ratios and incompatible elements distribution have several characteristic in common with equivalent rocks from Pontine Islands (Ventotene), Campania and Aeolian arc volcanoes. Conversely, the HKS rocks closely resemble the ultrapotassic rocks from the Roman Province ( 87 Sr/ 86 Sr = 0.709679–0.711102; δ 18 O cpx from +6.27 to +7.08 ‰). The high ratios of LILE (Large Ion Lithophile Elements: Rb, Cs, Th, U, K, LREE) and HFSE (High Field Strength Elements: Ta, Nb, Zr, Hf, Ti), and radiogenic isotope compositions of CA to HKS rocks indicate that all suites contain subduction-related components, and suggest a N-MORB-type mantle source variably contaminated by hydrous fluids and/or melts released by undergoing slabs, possibly during two distinct stages of metasomatism. The coexistence of ultra-alkaline and sub-alkaline orogenic magmatism, combined with tectonic, geophysical and geological evidence, support the possibility that the mantle beneath central-southern Italy (Ernici-Roccamonfina Province) was vertically zoned and produced different magma suites during time.

Pleistocene mafic volcanoes in the Puna–Cordillera Oriental boundary, NW-Argentina

Los Gemelos and El Saladillo are both monogenetic, strombolian, basaltic–shoshonitic volcanoes that constitute the easternmost recognized examples of mafic Plio-Quaternary volcanism in the southern Central Andes. Two regional faults delimit the borders of the Calchaquí valley, as thrusts with opposite vergence: the eastern Calchaquí fault and the western Toro Muerto fault. While Los Gemelos are set in the hanging wall of Calchaquí back-thrust fault, El Saladillo are set in the footwall of Toro Muerto fault. As Los Gemelos volcanoes have well preserved morphological features, we highlight some relationship between them and their tectonic setting. Kinematic data and one new measurement, that indicate right strike-slip movement in the vicinity of Los Gemelos during the Pleistocene–Holocene. The emplacement of these volcanoes should be related to a transpression zone parallel to the valley, where the alignment of the cones is outlining the trend of conjugated faults. The magmas were derived from a small degree of partial melting of an enriched, garnet-bearing mantle source. The analysed rocks have primitive signature (high Ni, Cr, Co and MgO concentrations; presence of chromite and forsteritic olivine) and evidence for crustal contamination with felsic rocks (quartz ± plagioclase ± K-feldspar xenocrysts with coronas, reaction rims and/or embayments; high 87Sr/ 86Sr ratios, negative εNd values). The high Cr and Ni content, high Mg# and low crystal content suggest that no major fractional crystallization occurred, therefore precluding long residence periods. Rapid magma ascent across 60 km of continental crust was guided by magmatic overpressure favoured by important tectonic stresses also avoiding significant residence time at upper crust depth. Thus, we invoke a process of assimilation during turbulent ascent (ATA) to explain the contamination at crustal levels. Los Gemelos volcanoes were formed around 35,000 yr. as inferred from the age of lacustrine sediments overlying the lava flows. These ages agree well with the age of paleolakes of tectonic origin in NW Argentina, suggesting a common tectonic cause for both effects.

Island-arc Ankaramites: Primitive Melts from Fluxed Refractory Lherzolitic Mantle

The distinctive island-arc ankaramites exemplified by the active Vanuatu arc may be produced by melting of refractory lherzolite under conditions in which melting is fluxed by H2O þ CO2. Parental picritic ankaramite magmas with maximum CaO/Al2O3 to 1 5 are produced by melt segregation from residual chromitebearing harzburgite at 1 5 GPa, 1320---1350 C. A pre-condition for derivation of such high CaO/Al2O3 melts from orthopyroxenebearing sources/residues is that pyroxenes have low Al2O3 (53 wt %), high Cr2O3 ( 1 wt %), and spinel, if it occurs, has Cr number 470. Bulk compositions have CaO/Al2O3 1 3, i.e. much higher than chondritic values. The effects of both (CO3) 2y and (OH)y dissolved in the silicate melt combine with the refractory wedge composition to produce ankaramitic picrite magmas that segregate from residual harzburgite at pressures of spinel stability. Other primitive arc and back-arc magmas such as boninites (low Ca and high Ca) share the primitive signatures of island-arc ankaramites (liquidus olivine Mg number 90, spinels with Cr number 470). Consideration of the relative proportions of Na2O, CaO and Al2O3 in these primitive arc magmas leads to the inference of a common factor of refractory mantle fluxed by differing agents. H2Orich fluid alone carries these refractory major element characteristics into the primitive melts (high-CaO boninites, tholeiitic picrites). Fluxing with dolomitic carbonatite melt, which may develop from C---O---H-fluids within the mantle wedge, generates high CaO/ Al2O3 sources and thus facilitates the formation of picritic ankaramites. Alternatively, melting may be fluxed by hydrous dacitic to rhyodacitic melt derived from the subducted slab (garnet amphibolite or eclogite melting). In this case, higher Na2O/CaO, lower CaO/ Al2O3 and higher SiO2 contents characterize the low-CaO boninites.