Evidence of crystallization in residual, Cl–F-rich, agpaitic, trachyphonolitic magmas and primitive Mg-rich basalt–trachyphonolite interaction in the lava domes of the Phlegrean Fields (Italy)

2011 ◽  
Vol 149 (3) ◽  
pp. 532-550 ◽  
Author(s):  
LEONE MELLUSO ◽  
ROBERTO DE' GENNARO ◽  
LORENZO FEDELE ◽  
LUIGI FRANCIOSI ◽  
VINCENZO MORRA
Keyword(s):  
Basaltic Magma ◽  
Mafic Magma ◽  
Alkali Feldspar ◽  
Campanian Ignimbrite ◽  
Phlegrean Fields ◽  
Lava Domes ◽  
Mineral Assemblages ◽  
The Subject ◽  
Magma Crystallization ◽  
Recent Activity

AbstractThe lava domes in the northwestern (Cuma), northern (Punta Marmolite) and central (Accademia) parts of the Phlegrean Fields are the subject of this study. The Cuma and Punta Marmolite trachyphonolitic lava domes are among the oldest Phlegrean products cropping out. The Cuma rocks have an agpaitic groundmass, with early alkali feldspar, Fe-rich clinopyroxene, Fe-edenite and sodalite and late rosenbuschite, fluorite, baddeleyite, pyrochlore, britholite, monazite, aegirine (often Zr-rich) and exceptionally Fe–Mn-rich olivine. The bulk-rock compositions at Cuma have some of the highest concentrations of Zn, Mn, Zr, Nb, Th, U and lanthanides among the Phlegrean Fields rocks, and some of the lowest MgO, P2O5, Sr, Eu and Ba. The Punta Marmolite dome is chemically less evolved, and lacks characteristic agpaitic minerals, but features alkali feldspar, sodalite, nepheline and relatively Na-poor, Fe-rich hedenbergite, with rare Ca-rich plagioclase xenocryst cores. The Accademia dome, belonging to the recent activity, is latitic to trachytic in composition, has highly forsteritic olivine (with chromiferous spinel inclusions), calcic plagioclase and Mg-rich diopside (± phlogopite) xenocrysts in an evolved host rock (with phenocrysts and microlites of alkali feldspar, Fe-rich clinopyroxene, Fe-rich amphibole, magnetite, Fe-rich olivine and accessory baddeleyite, zirconolite and fluorite). There is clear evidence of open-system magma crystallization in the form of interaction between a crystallizing, primitive shoshonitic basalt in a reservoir already filled by rather evolved trachytic magma. The magmatic evolution towards the evolved compositions is dominated by crystallization of more and more Na-rich alkali feldspar in a Cl-, F-rich and relatively H2O-poor environment. Input of mafic magma is evident in many trachytic eruptions of the Phlegrean Fields and even in the products of the Campanian Ignimbrite, but eruptions having mineral assemblages rich in xenocryst phases as well as eruptions virtually free of mafic magma input are also frequently observed throughout the history. This suggests a variable pattern of open- and closed-system crystallization, which may or may not be linked to explosive activity, and that can be caused by intermittent supply of basaltic magma from depth.

A Grenville-age layered intrusion in the subsurface of west Texas: petrology, petrography, and possible tectonic setting

1995 ◽  
Vol 32 (12) ◽  
pp. 2159-2166 ◽  
Author(s):  
Hulusi Kargi ◽  
Calvin G. Barnes
Keyword(s):  
Tectonic Setting ◽  
Basaltic Magma ◽  
Layered Intrusion ◽  
Mafic Magma ◽  
Magma Source ◽  
Rock Types ◽  
Hornblende Gabbro ◽  
Tectonic Environment ◽  
Extensional Tectonic ◽  
General Order

The Nellie intrusion is a thick (more than 4420 m) mafic to ultramafic layered intrusion with a radiometric age of ~1163 Ma. Rock types change abruptly with stratigraphic height and include norite, pyroxenite, gabbronorite, hornblende gabbro, gabbro, anorthosite, harzburgite, and lherzolite. Norite is most abundant, but gabbro and hornblende gabbro are locally abundant. Rare olivine-rich layers are also present. The general order of crystallization was olivine, orthopyroxene, plagioclase + clinopyroxene, and hornblende. Mg#'s, expressed as 100 Mg/(Mg + Fe), range from 76.3 to 85.8 for olivine, 56.7 to 84.9 for orthopyroxene, 62.5 to 90.3 for clinopyroxene, and 52.4 to 82.8 for amphibole. Mg#'s vary with height and display abrupt reversals, which indicate open-system addition of new mafic magma. Eleven cyclic units were identified on the basis of evidence for injection of basaltic magma; these can be grouped into three megacyclic units. The abundance of orthopyroxene, and mineral compositional evidence for Fe enrichment within cyclic units, indicates that parental magmas were subalkaline and tholeiitic. Plagioclase in equilibrium with olivine ranges from An65 to An46, which precludes an arc-related magma source. Although the intrusion is approximately coeval with Keweenawan magmatism and with emplacement of diabasic dikes in western North America, it is dissimilar in detail to both suites of rocks. Nevertheless, its composition and geophysical setting are consistent with emplacement in an extensional tectonic environment.

Initial melting in alkali feldspar-plagioclase-quartz systems

1968 ◽  
Vol 105 (4) ◽  
pp. 325-337 ◽  
Author(s):  
Daniel F. Weill ◽  
Albert H. Kudo
Keyword(s):  
Alkali Feldspar ◽  
Melting Range ◽  
Melting Temperatures ◽  
Considerable Portion ◽  
Mineral Assemblages ◽  
Initial Melting

SUMMARYThe beginning of melting of mineral assemblages of alkali feldspar, plagioclase and quartz in the system Ab-Or-Q-An cannot be treated in terms of eutectic points in subsystems which are defined on the basis of the ratio Ab/ An. Such subsystems do not exhibit unique melting temperatures or unique compositions of the first liquid produced. It is shown theoretically and demonstrated experimentally that these three minerals may coexist with liquid over a considerable portion of the melting range.

The ‘Great Antrum’ at Baiae: A Preliminary Report

1967 ◽  
Vol 35 ◽  
pp. 102-112 ◽  
Author(s):  
R. F. Paget
Keyword(s):  
United States Navy ◽  
Hot Spring ◽  
The United States ◽  
Kind Permission ◽  
Phlegrean Fields ◽  
British School ◽  
The Subject ◽  
The One ◽  
Short Tunnel ◽  
Made In

The complex of tunnels and buildings described in this article was discovered by Keith W. Jones of the United States Navy and myself in the course of our general exploration of the underground antiquities of the Phlegrean Fields, made with the kind permission of Professor Alfonso de Franciscis, the Superintendent of Antiquities for Campania. They are the subject of a book recently published by myself (In the Footsteps of Orpheus, Hale, London 1967), but in view of their very unusual nature I have gladly accepted an invitation by the Director of the British School to contribute to the Papers a short factual account, together with the plans we made in the course of our survey (fig. 1).When the terraced structures overlooking the bay and port of Baia were excavated in 1956–58, many tunnel entrances were uncovered. With the exception of the one short tunnel leading to the hot spring at the rear of the so-called Temple of Mercury, and a few obvious drainage ducts, the tunnels are all concentrated in the areas marked III and IV on the plans in the guide book, The Phlegrean Fields by A. Maiuri (3rd ed., 1958).

Mafic-silicic layered intrusions: the role of basaltic injections on magmatic processes and the evolution of silicic magma chambers

1996 ◽  
Vol 87 (1-2) ◽  
pp. 233-242 ◽  
Author(s):  
R. A. Wiebe
Keyword(s):  
Basaltic Magma ◽  
Mafic Magma ◽  
Silicic Magma ◽  
Granitic Magma ◽  
Magma Chambers ◽  
Mechanical Mixing ◽  
Diffusive Convection ◽  
Type Granite ◽  
Mafic Magmas ◽  
Silicic Magmas

ABSTRACT:Plutonic complexes with interlayered mafic and silicic rocks commonly contain layers (1–50 m thick) with a chilled gabbroic base that grades upwards to dioritic or silicic cumulates. Each chilled base records the infusion of new basaltic magma into the chamber. Some layers preserve a record of double-diffusive convection with hotter, denser mafic magma beneath silicic magma. Processes of hybridisation include mechanical mixing of crystals and selective exchange of H2O, alkalis and isotopes. These effects are convected away from the boundary into the interiors of both magmas. Fractional crystallisation aad replenishment of the mafic magma can also generate intermediate magma layers highly enriched in incompatible elements.Basaltic infusions into silicic magma chambers can significantly affect the thermal and chemical character of resident granitic magmas in shallow level chambers. In one Maine pluton, they converted resident I-type granitic magma into A-type granite and, in another, they produced a low-K (trondhjemitic) magma layer beneath normal granitic magma. If comparable interactions occur at deeper crustal levels, selective thermal, chemical and isotopic exchange should probably be even more effective. Because the mafic magmas crystallise first and relatively rapidly, silicic magmas that rise away from deep composite chambers may show little direct evidence (e.g. enclaves) of their prior involvement with mafic magma.

scholarly journals Rozwój i stan krajobrazu językowego – przypadek języka wilamowskiego

Adeptus ◽  
2019 ◽  
Author(s):  
Justyna Majerska-Sznajder
Keyword(s):  
Cultural Landscape ◽  
Western Europe ◽  
Linguistic Landscape ◽  
Grass Roots ◽  
The Past ◽  
Current State ◽  
Recent Interest ◽  
The Subject ◽  
Recent Activity ◽  
Grass Roots Initiatives

The development and current state of the linguistic landscape – the case of the Wymysorys languageWymysorys is a micro-language with Germanic roots spoken by the residents of Wilamowice, a small Silesian town located between Oświęcim and Bielsko-Biała, where it was brought by settlers from Western Europe in the thirteenth century. It has been the subject of scholarly interest among specialists in a number of fields, not only linguistics and ethnology, since the early twentieth century. Following a ban issued by local authorities in 1945, the use of Wymysorys was prohibited and public manifestations of local culture were severely punished. This policy resulted in a drastic decline of the number of its users. The recent interest of researchers is focused not only on the documentation of Wymysorys or its sociolinguistic situation in the past and today, but also on the effects of its revitalization in the last decade. Despite the lack of institutional support, the users’ community has been engaged in grass-roots initiatives leading to the emergence of Wymysorys in the cultural landscape. Recent activity of its users indicates that the language has already spread beyond the circles of local activists and, after years of persecution, functions again in society, evolving and taking new forms. Rozwój i stan krajobrazu językowego – przypadek języka wilamowskiegoJęzyk wilamowski, którym posługują się mieszkańcy Wilamowic (wym. Wymysoü), od początku XX wieku interesuje naukowców wielu dziedzin – nie tylko lingwistów i etnologów. Został on przywieziony przez osadników z Europy Zachodniej w XIII wieku na teren obecnych Wilamowic – małego miasteczka na Śląsku leżącego między Oświęcimiem a Bielskiem-Białą. Na skutek zakazu wydanego przez władze lokalne w 1945 roku używanie wilamowskiego było zabronione, a wszelkie publiczne przejawy odmiennej kultury ostro karane, w związku z czym liczba użytkowników wilamowskiego zaczęła drastycznie maleć. Zainteresowanie badaczy ostatnimi czasy wzbudza nie tylko kwestia dokumentacji tego mikrojęzyka o germańskich korzeniach czy stan etnolingwistyczny. Obserwacji podlegają również obecne efekty zaaplikowanych w ostatniej dekadzie procesów rewitalizacji językowej i zmiany lokalnej, a także państwowej polityki językowej. Mimo braku instytucjonalnego wsparcia, społeczeństwo użytkowników oddolnie podejmuje inicjatywy, których efektem jest między innymi pojawianie się wilamowskiego w krajobrazie kulturowym. Ostatnie działania użytkowników języka świadczą o tym, że opuścił już kręgi lokalnych aktywistów i ponownie, po latach zakazu, funkcjonuje samodzielnie w społeczeństwie, ewoluując i przybierając nowe formy.

The origin of sapphires: U–Pb dating of zircon inclusions sheds new light

1990 ◽  
Vol 54 (374) ◽  
pp. 113-122 ◽  
Author(s):  
Robert R. Coenraads ◽  
F. Lin Sutherland ◽  
Peter D. Kinny
Keyword(s):  
Basaltic Magma ◽  
Alkali Feldspar ◽  
Upward Movement ◽  
Central Province ◽  
Incompatible Elements ◽  
Complex Process ◽  
Zircon Fission Track ◽  
Basaltic Composition ◽  
Fission Track Ages ◽  
Isotope Dating

AbstractUranium-lead isotope dating of two zircon inclusions in sapphires from the Central Province, NSW. gives ages of 35.9 ± 1.9 and 33.7 ± 2.1 million years (Ma). These ages fall within the range of basalt potassium-argon ages of 19 to 38Ma and zircon fission track ages of 2 to 49Ma for the timing of volcanism of the Central Province, NSW. These data, combined with the observation that corundum is found associated with many alkali basaltic provinces, indicate a genetic link between the growth of large corundum crystals and the processes involved in alkali basaltic magma generation. The reported failure of experimental attempts to grow corundum from a corundum-bearing basaltic composition, and more significantly, the abundance of incompatible elements such as U, Th, Zr, Nb and Ta in inclusion minerals indicate that the crystallization process is not simple. Corundum and the other minerals found as its inclusions (zircon, columbite, thorite, uranium pyrochlore, alkali feldspar etc.) could not have crystallized from most basaltic compositions. A more complex process must occur in which crystallization takes place when there are high proportions of incompatible elements and volatiles in the melt. These crystallization products are then carried to the surface by upward movement of later magmas. The extent of this process presumably determines whether a particular basaltic province carries sufficient corundum to be worked into economic concentrations of sapphire.

scholarly journals Evidence of crystallization in residual, Cl–F-rich, agpaitic, trachyphonolitic magmas and primitive Mg-rich basalt–trachyphonolite interaction in the lava domes of the Phlegrean Fields (Italy) – CORRIGENDUM

2012 ◽  
Vol 149 (3) ◽  
pp. 551-551
Author(s):  
LEONE MELLUSO ◽  
ROBERTO DE' GENNARO ◽  
LORENZO FEDELE ◽  
LUIGI FRANCIOSI ◽  
VINCENZO MORRA
Keyword(s):  
Chemical Composition ◽  
Chemical Formula ◽  
Phlegrean Fields ◽  
Lava Domes

In an Original Article by Melluso et al. recently published online (1 November 2011), the mineral named as rosenbuschite should be named låvenite throughout, having the chemical composition broadly corresponding to the chemical formula (Na, Ca)2(Mn, Fe)(Zr, Ti)Si2O7(O, OH, F)2 (see Sørensen, 1997).

Sign in / Sign up

Export Citation Format

Share Document