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Published: 9 March 2023

Last updated: 10 March 2023

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1

Fernández-Roig, M., G. Galán, and E. Mariani. "Crystal preferred orientation of olivine in mantle xenoliths from Catalonia (NE Spain) Orientación cristalina preferente del olivino en xenolitos mantélicos de Cataluña (NE de España)." Trabajos de Geología 36, no. 36 (September 12, 2018): 119. http://dx.doi.org/10.17811/tdg.36.2016.119-138.

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Abstract: Mantle xenoliths in Neogene-Quaternary alkaline volcanic rocks from the Catalan Volcanic Zone indicate that ≪anhydrous≫ spinel lherzolites, harzburgites and much subordinate olivine websterites form the lithospheric mantle of NE Iberian Peninsula. Olivine crystal preferred orientation, determined by indexation of electron-backscattered diffraction patterns, provides three types of deformation fabric: a dominant [010]-fiber type in peridotites and websterites equilibrated at high temperature, and subordinate orthorhombic and [100]-fiber types, which appear mostly in porphyroclas tic and equigranular lherzolites equilibrated at lower temperature.Keywords: Lithospheric mantle, lherzolites, harzburgites, websterites, olivine, deformation fabric.Resumen: Los xenolitos mantelitos en lavas alcalinas neógeno-cuaternarias de la Zona Volcánica de Cataluña indican que lherzolitas y harzburgitas ≪ anhidras≫ y con espinela son las rocas predominantes en el manto litosférico del NE de la Península Ibérica, con presencia también subordinada de websteritas olivínicas. Las orientaciones cristalográficas preferentes del olivino, determinadas por indexación de los espectros de difracción de electrones retrodispersados, muestran tres tipos de fábrica de deformación: una dominante, tipo axial [010], en peridotitas y websteritas equilibradas a alta temperatura, y otras subordinadas, de tipo ortorrómbico y axial [100], que aparecen en lherzolitas porfidoclásticas y equigranulares equilibradas a menor temperatura.Palabras clave: Manto litosférico, lherzolitas, harzburgitas, websterita, olivino, fábricas de deformación

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2

Nikitina, L. P., Yu B. Marin, M. Yu Koreshkova, S. A. Sergeev, B. V. Belyatsky, R. Sh Krymsky, E. S. Bogomolov, M. S. Babushkina, and A. Tokusheva. "Xenoliths of High-Alumina Pyroxenites in the Basalts of the Sigurd Volcano, Spitsbergen Island (Svalbard Archipelago), as Indicators of the Paleozoic Geodynamics of the Regional Lithosphere." Russian Geology and Geophysics 63, no. 10 (October 1, 2022): 1093–110. http://dx.doi.org/10.2113/rgg20214389.

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Abstract —Xenoliths of high-alumina pyroxenites in the Quaternary basalts of the Sigurd Volcano of West Spitsbergen are spinel and spinel–garnet clinopyroxenites, spinel–garnet websterites, and websterites. The granoblastic texture with relics of subhedral magmatic texture, the change of mineral assemblages, and the signs of partial melting in the xenoliths reflect their multistage formation. The goal of our study was to determine the sequence and thermodynamic conditions of the change of mineral assemblages and to establish their age by Re–Os, U–Pb, Sm–Nd, and Rb–Sr isotope dating. It has been established that the primary assemblage in the pyroxenites, which included high-alumina Opx, Cpx, and Spl, was transformed in several stages: (1) Spl→Grt replacement with the formation of garnet-containing websterites and clinopyroxenites, (2) development of kelyphitic Opx–Spl rims over Grt grains, (3) formation of Amph, (4) exsolution with the formation of Cpx and Opx, and (5) partial melting. Comparison of the obtained results with published data shows that the primary assemblage is similar in Al2O3/MgO ratio to Opx + Cpx ± Spl cumulates resulted from the crystallization of basaltic melts at 1.2 GPa and the degree of crystallization of ~15%, i.e., in the lower crust (at 2.0 GPa, Grt and Cpx crystallize from the solution). The equilibrium parameters of the Grt–Opx assemblage in the pyroxenites are 1060–1310 ºC and 2.2–3.3 GPa; in the P–T diagram, their points are localized below the Spl→Grt phase transition curve, in the system CaO–MgO–Al2O3–SiO2, thus corresponding to the model continental geotherm with a surface heat flow density of 60 mV/m2 and somewhat higher. This indicates the Spl→Grt replacement and the formation of garnet-containing pyroxenites in the shallow-depth upper mantle. The formation of kelyphitic Opx–Spl rims over the Grt grains indicates a subsequent temperature and pressure decrease to values above the Grt→Spl phase transition curve. This is confirmed by the presence of exsolution structures in pyroxene, which formed when the temperature decreased by 100–150 ºC. The Re and Os isotope composition in the bulk samples of Spl–Grt websterites that did not undergo partial melting corresponds to an age of 457.0 ± 3.5 Ma, which reflects the time of transformation of the primary Cpx–Opx–Spl assemblage into a garnet-including one. A similar value (488.6 ± 5.9 Ma) was obtained by U–Pb dating of zircon from Spl–Grt websterite, also without signs of melting. Zircon crystals from Spl–Grt clinopyroxenite with clear signs of partial melting have typomorphic features of autochthonous magmatic zircons. They form a single age cluster of 310.7 ± 3.3 Ma, which marks the age of melt crystallization in the pyroxenites. Thus, Spl pyroxenites are, most likely, Opx + Cpx ± Spl cumulates, products of crystallization of basaltic melts in the lower crust. The subsequent Spl→Grt replacement and the formation of garnet-containing websterites and clinopyroxenites in the shallow-depth upper mantle can be regarded as an indicator of the delamination of the continental crust into the mantle, and the Re–Os isochron date of 457.0 ± 3.5 Ma is the most likely upper age bound of the crust delamination into the mantle. The subsequent uplifting of the Spitsbergen lithosphere, which was expressed as the formation of kelyphitic Opx–Spl rims over garnet, exsolution in pyroxene, and partial melting, was not far in time from the delamination stage and lasted ≤ 300 Ma.

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3

Serri, Giancarlo, Réjean Hébert, and Roger Hekinian. "Petrology of a plagioclase-bearing olivine websterite from the Gorringe Bank (northeastern Atlantic Ocean)." Canadian Journal of Earth Sciences 25, no. 4 (April 1, 1988): 557–69. http://dx.doi.org/10.1139/e88-054.

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Samples of plagioclase olivine websterite included in variously serpentinized harzburgite and lherzolite tectonites were collected by submersible on the northwest flank of the Gettysburg Seamount near 36°N in the northeastern Atlantic. The websterite exhibits a coarse porphyroclastic texture (70% porphyroclasts), and the composition of the pyroxene shows a progressive re-equilibration with decreasing temperature (and probably pressure) under anhydrous conditions from a near-solidus temperature of ~1250 °C (porphyroclasts) down to ~700 °C (granoblasts). In situ observations, as well as textural, mineralogical, and chemical evidence, suggest that the websterite can best be interpreted as a heteradcumulate rock that crystallized on the walls of narrow conduits from a MORB type magma flowing through the residual tectonites.The Mg #'s (= 100 × Mg/(Mg + Fe2+)) of coexisting clinopyroxene, orthopyroxene, and olivine (91.5–90.5, 90.0–89.7, and 89.5–88.5, respectively), the plagioclase composition (An88.7–87.9), and the mineral minor-element distribution are not compatible with the crystallization at low pressure of the websterite from N-MORB type parental magma. Instead, the calculated composition of the liquid in equilibrium with the websterite's most magnesian minerals and the bulk-rock composition are more akin to those of a poorly differentiated T-MORB than of N-MORB parental magma. Phase relations and mineral compositions produced by anhydrous melting experiments for synthetic and natural systems indicate that the pressure of crystallization of the plagioclase olivine websterite is constrained within the narrow range of 7–10 kbar. It is thought that fractionation of websterite is probably a minor but significant petrologic factor of MORB type magma differentiation. It could explain some of the compositional variations observed in magnesian MORB.

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ANKER, ARTHUR, CARLA HURT, and NANCY KNOWLTON. "Revision of the Alpheus websteri Kingsley, 1880 species complex (Crustacea: Decapoda: Alpheidae), with revalidation of A. arenensis (Chace, 1937)." Zootaxa 1694, no. 1 (January 31, 2008): 51. http://dx.doi.org/10.11646/zootaxa.1694.1.3.

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The Alpheus websteri Kingsley, 1880 species complex is revised. Alpheus websteri s. str. is redefined and restricted to the western Atlantic, ranging from the type locality in the Florida Keys to northeastern Brazil. The eastern Pacific A. arenensis (Chace, 1937), formerly a synonym of A. websteri, and the eastern Atlantic A. fagei Crosnier and Forest, 1966, are shown to be distinct from A. websteri morphologically, genetically and also by color pattern. Morphology, genetics and color patterns all suggest that A. websteri and A. arenensis are transisthmian sister species, with A. fagei being their closest relative. Complete synonymy, color photographs and GenBank barcodes (COI) are provided for all three species.

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5

Duan, Xianzhe, Hongjie Shen, Nan Li, Wenzhou Xiao, Qinglin Sui, Haiyang He, Peng Feng, and Zhenping Tang. "Transformation of the Sub-Continental Lithospheric Mantle Beneath the North China Craton (NCC): Constraints from the Geochemical Characteristics of Olivine Websterite Xenoliths and Their Minerals in the Cenozoic Basalts from Hannuoba." Minerals 12, no. 4 (March 24, 2022): 401. http://dx.doi.org/10.3390/min12040401.

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The sub-continental mantle beneath North China Craton (NCC) has attracted extensive attention in the past decades because of its dramatic transformation from an old, cold, thick, and refractory mantle to a juvenile, hot, thinner, and fertile mantle. However, the transformation mechanism remains largely controversial. The mantle xenoliths entrapped in basalts, as petrogenetic indicators, can provide an important window to reveal the evolution of the sub-continental lithospheric mantle. In this study, we present a systematical study on the geochemical characteristics of the olivine websterite xenoliths and their minerals in the Cenozoic basalts in the Hannuoba region located at the central orogenic belt of the NCC. The results, compared with the geochemical data of Paleozoic and Meosozic peridotites, the Cenozoic composite pyroxenites as well as the global cumulate pyroxenites, demonstrate that: (1) The source of the websterite is probably the lithospheric mantle, which is mainly newly accreted, but with small amounts of ancient mantle residues. The source may be contaminated by different degrees of crustal materials. The high Nb/Ta ratios (11.36–20.57) of the websterite indicate that the Ti-bearing minerals (such as rutile) are probably involved in the source; (2) The websterite is more likely to be produced as a result of interaction of mantle peridotite with the silica-rich melts that are mainly derived from the asthenospheric mantle and also contributed by the crustal materials; (3) The metasomatic crustal melts might be derived from the subducted Paleo-Pacific plate. These melts interacted with the lithospheric mantle can significantly transform the chemical composition of the lithospheric mantle, and consequently play an important role in the destruction of the NCC. An important implication for the destruction of the NCC is further discussed.

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Canil, Dante, Mark Brearley, and Christopher M. Scarfe. "Petrology of ultramafic xenoliths from Rayfield River, south-central British Columbia." Canadian Journal of Earth Sciences 24, no. 8 (August 1, 1987): 1679–87. http://dx.doi.org/10.1139/e87-161.

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One hundred mantle xenoliths were collected from a hawaiite flow of Miocene–Pliocene age near Rayfield River, south-central British Columbia. The massive host hawaiite contains subrounded xenoliths that range in size from 1 to 10 cm and show protogranular textures. Both Cr-diopside-bearing and Al-augite-bearing xenoliths are represented. The Cr-diopside-bearing xenolith suite consists of spinel lherzolite (64%), dunite (12%), websterite (12%), harzburgite (9%), and olivine websterite (3%). Banding and veining on a centimetre scale are present in four xenoliths. Partial melting at the grain boundaries of clinopyroxene is common and may be due to natural partial melting in the upper mantle, heating by the host magma during transport, or decompression during ascent.Microprobe analyses of the constituent minerals show that most of the xenoliths are well equilibrated. Olivine is Fo89 to Fo92, orthopyroxene is En90, and Cr diopside is Wo47En48Fs5. More Fe-rich pyroxene compositions are present in some of the websterite xenoliths. The Mg/(Mg + Fe2+) and Cr/(Cr + Al + Fe3+) ratios in spinel are uniform in individual xenoliths, but they vary from xenolith to xenolith. Equilibration temperatures for the xenoliths are 860–980 °C using the Wells geothermometer. The depth of equilibration estimated for the xenoliths using geophysical and phase equilibrium constraints is 30–40 km.

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7

Gilotti, J. A. "Eclogites and related high-pressure rocks from North-East Greenland." Rapport Grønlands Geologiske Undersøgelse 162 (January 1, 1994): 77–90. http://dx.doi.org/10.34194/rapggu.v162.8250.

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Eclogite, gamet clinopyroxenite, gamet websterite and websterite bodies were discovered within the Skærfjorden gneiss complex during recent mapping in North-East Greenland. These eclogitic pods extend from Danmarkshavn (c. 76° 40'N) to the northern limit of the area mapped (78°N), and attest to widespread high-pressure metamorphism. Eclogites with the assemblage omphacite + garnet ± quartz ± futile are common. The protoliths of some of the eclogites were xenoliths within the precursor batholiths to the gneisses. Field relations, regional correlations and preliminary geochronology indicate that the eclogite facies metamorphism is Caledonian. The eclogites formed at minimum pressures between 10-15 kilobars and temperatures between 600–900°C, and hence are the medium-temperature type typically formed in over-thickened crust during continent collision.

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Le Roux, V., S. G. Nielsen, C. Sun, and L. Yao. "Dating layered websterite formation in the lithospheric mantle." Earth and Planetary Science Letters 454 (November 2016): 103–12. http://dx.doi.org/10.1016/j.epsl.2016.08.036.

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9

Monnier, Christophe, Jacques Girardeau, Hariady Permana, Jean-Pierre Rehault, Hervé Bellon, and Jo Cotten. "Dynamics and age of formation of the Seram-Ambon ophiolites (Central Indonesia)." Bulletin de la Société Géologique de France 174, no. 6 (November 1, 2003): 529–43. http://dx.doi.org/10.2113/174.6.529.

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Abstract The Seram-Ambon ophiolitic series comprise peridotites, websterites, gabbros and lavas. Petro-geochemical data show that the peridotites are weakly depleted rocks, except for the rare Cpx-free harzburgites. They underwent a sub-solidus metamorphic re-equilibration in the plagioclase field. The associated websterites and gabbros display various chemical features, allowing to define 3 types of websterites and 2 groups of gabbros. They have mostly BAB characteristics (presence of negative anomalies in Nb, Zr, Ti and Y), except the group 2 gabbros which have N-MORB features and the type 3 websterites which bear adakitic affinities. Lavas also display a variety of compositions, including high-Mg IAT and Mg-rich BABB with sub-alkaline affinities. Both IAT and BABB display high Th/Nb ratios which support an origin close to a continental crust environment. Our 20 to 15 Ma 40K/40Ar ages calculated for the BABB and 15-9 Ma for the IAT show that the basin and arc formed in a very short span of time, before their obduction 9–7 Ma ago [Linthout et al., 1997]. Considering the paleogeographic situation in the Miocene [Haile, 1979 ; Haile, 1981] and our data, we propose that the Seram-Ambon ophiolites formed during the early Miocene in a small, short-lived (10 Ma), transtensive basin bordered on its east by an active margin and on its western part by a passive continental margin over which it was later obducted towards the SW direction.

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LaFlamme, Crystal, Christopher R. M. McFarlane, and David Corrigan. "Neoarchean Mantle-derived Magmatism within the Repulse Bay Block, Melville Peninsula, Nunavut: Implications for Archean Crustal Extraction and Cratonization." Geoscience Canada 42, no. 3 (July 29, 2015): 305. http://dx.doi.org/10.12789/geocanj.2015.42.065.

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SUMMARYThe Repulse Bay block (RBb) of the southern Melville Peninsula, Nunavut, lies within the Rae craton and exposes a large (50,000 km2) area of middle to lower crust. The block is composed of ca. 2.86 Ga and 2.73–2.71 Ga tonalite-trondhjemite-granodiorite (TTG) and granitic gneiss that was derived from an older 3.25 and 3.10 Ga crustal substrate. This period of crustal generation was followed by the emplacement of ca. 2.69–2.66 Ga enderbite, charnockite, and granitoid intrusions with entrained websterite xenoliths. These voluminous batholith-scale bodies (dehydrated and hydrated intrusions), and the associated websterite xenoliths, have similar whole rock geochemical properties, including fractionated light rare earth element (LREE)–heavy (H)REE whole rock patterns and negative Nb, Ti, and Ta anomalies. Dehydrated intrusions and websterite xenoliths also contain similar mineralogy (two pyroxene, biotite, interstitial amphibole) and similar pyroxene trace element compositions. Based on geochemical and mineralogical properties, the two lithologies are interpreted to be related by fractional crystallization, and to be the product of a magmatic cumulate processes. Reworking of the crust in a ca. 2.72 Ga subduction zone setting was followed by ca. 2.69 Ga upwelling of the asthenospheric mantle and the intrusion of massif-type granitoid plutons. Based on a dramatic increase in FeO, Zr, Hf, and LREE content of the most evolved granitoid components from the 2.69–2.66 Ga cumulate intrusion, we propose that those granitoid plutons were in part derived from a metasomatized mantle source enriched by fluids from the subducting oceanic slab that underwent further hybridization (via assimilation) with the crust. Large-scale, mantle-derived Neoarchean sanukitoid-type magmatism played a role in the development of a depleted lower crust and residual sub-continental lithospheric mantle, a crucial element in the preservation of the RBb.RÉSUMÉLe bloc de Repulse Bay (RBb) dans le sud de la péninsule de Melville, au Nunavut, est situé dans le craton de Rae et expose une large zone (50 000 km2) de croûte moyenne à inférieur. Ce bloc est composé de tonalite-trondhjémite-granodiorite (TTG) daté à ca. 2,86 Ga et 2,73–2,71 Ga, et de gneiss granitique dérivé d’un substrat crustal plus ancien daté à 3,25 Ga et 3,10 Ga. Cette période de croissance crustale a été suivie par la mise en place entre ca. 2,69 et 2,66 Ga d’intrusions d’enderbite, charnockite et de granitoïde incluant des xénolites d’entraînement de websterite. Ces intrusions de taille batholitique (intrusions déshydratées et hydratées) ainsi que les xénolites d’entraînement de websterite associés, ont des propriétés géochimiques sur roche totale semblables notamment leurs profils de fractionnement des terres rares légers (LREE) et des terres rares lourds (HREE) ainsi que leurs anomalies négatives en Nb, Ti et Ta. Les intrusions déshydratées et les xénolites de websterite ont aussi des minéralogies similaires (deux pyroxènes, biotite, amphibole interstitielle) ainsi que des compositions semblables en éléments traces de leurs pyroxènes. Étant donné leurs propriétés géochimiques et minéralogiques, ces deux lithologies sont interprétées comme provenant d’une cristallisation fractionnée, et comme étant le produit de processus d'accumulations magmatiques. Le remaniement de la croûte dans un contexte de subduction vers ca. 2,72 Ga, a été suivi vers ca. 2,69 Ga d’une remontée du manteau asthénosphérique et de l’intrusion de granitoïdes de type massif. D'après l’importante augmentation en FeO, Zr, Hf et LREE dans les granitoïdes les plus évolués du magmatisme ayant pris place entre ca. 2,69 Ga et 2,66 Ga, nous proposons que ces plutons aient été en partie dérivés d’une source mantélique métasomatisée enrichies par des fluides d’une plaque océanique en subduction et qui a subi une hybridation supplémentaire (par assimilation) avec la croûte. Le magmatisme néo-archéen de type sanukitoïde, dérivé du manteau et de grande échelle, a joué un rôle dans le développement d’une croûte inférieure et d’un manteau lithosphérique continental résiduel appauvri, un élément déterminant pour la préservation du RBb.

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11

RODEWALD, NICOLA, REINETTE SNYMAN, and CAROL A. SIMON. "Worming its way in—Polydora websteri (Annelida: Spionidae) increases the number of non-indigenous shell-boring polydorin pests of cultured molluscs in South Africa." Zootaxa 4969, no. 2 (May 11, 2021): 255–79. http://dx.doi.org/10.11646/zootaxa.4969.2.2.

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Polychaete worms of the Polydora-complex (commonly referred to as polydorins) include some of the most common pests of cultured molluscs. Modern culture of molluscs, particularly oysters, is associated with large-scale movement of stock which facilitates movement of polydorins either as “hitchhikers” on the transported molluscs or in the packaging. In 2009, a species identified as Polydora cf. ciliata Johnston, 1838 was reported from oysters in a culture facility in Port Elizabeth, South Africa. Since then, more specimens of this species were recorded on farmed oysters from Namibia, Kleinzee and Paternoster on the west coast of South Africa, but tentatively reidentified as Polydora cf. websteri Hartman in Loosanoff and Engle, 1943 based on morphology and limited genetic evidence. The main aim of this study is therefore to clarify the identity of these specimens by integrating morphological and genetic (mitochondrial COI, Cyt b and nuclear 18S rRNA) evidence. Specimens from South Africa match the morphology of the lectotype of P. websteri and are morphologically and genetically very similar to P. websteri from Australia, China, Japan, and the east, gulf and west coasts of the USA. This confirms the presence of P. websteri in South Africa, making this the second most widespread polydorin pest of aquaculture known. Understanding the full distribution range of the species will help to better understand its global route of invasion and consequently assist with preventing or at least minimising further spread. Polydora websteri increases the number of polydorin pests in South Africa to seven.

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Lisitskaya, E. V., and N. A. Boltachova. "ABOUT REGENERATION OF ALIEN POLYCHAETE POLYDORA WEBSTERI (ANNELIDA: SPIONIDAE)." Russian Journal of Biological Invasions 14, no. 3 (August 30, 2021): 24–31. http://dx.doi.org/10.35885/1996-1499-2021-14-3-24-31.

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New data on the regenerative capacity of the invader polychaete Polydora websteri Hartman in Loosanoff & Engle, 1943 have been obtained. The material was collected in 2019-2020 in the area of Sevastopol. Polychaetes were extracted from blisters in the valves of an exotic oyster species for the Black Sea - Crassostrea gigas (Thunberg, 1793). Molluscs were grown on an oyster farm. Polychaetes were kept in aquariums with filtered seawater at a temperature from 8.8 to 25.8 °C and a salinity of 17.5-17.8‰. Under laboratory conditions, body segments were removed from the worms and their recovery was observed. It was found that P. websteri regenerated both the anterior and posterior parts of the body. The minimum number of segments capable to simultaneously restore both anterior and posterior regions is three mid-body segments. The regeneration process in P. websteri depends significantly on the water temperature. In the range of 8.8-26 °С, a direct relationship was established between the water temperature and the number of regenerated individuals. An inverse relationship was found between the water temperature and the time spent on regenerating the lost fragments. When warming up the water, the proportion of regenerated P. websteri increased from 15 to 87%, and the duration of regeneration decreased 2.5 times.

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Viljoen, K. S., S. H. Perritt, and I. L. Chinn. "An unusual suite of eclogitic, websteritic and transitional websteritic-lherzolitic diamonds from the Voorspoed kimberlite in South Africa: Mineral inclusions and infrared characteristics." Lithos 320-321 (November 2018): 416–34. http://dx.doi.org/10.1016/j.lithos.2018.09.034.

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14

Stolz, A. J. "Fluid activity in the lower crust and upper mantle: mineralogical evidence bearing on the origin of amphibole and scapolite in ultramafic and mafic granulite xenoliths." Mineralogical Magazine 51, no. 363 (December 1987): 719–32. http://dx.doi.org/10.1180/minmag.1987.051.363.13.

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AbstractXenoliths in an olivine nephelinite from the McBride Province, North Queensland, include Cr-diopside lherzolites, spinel and garnet websterites, felsic, 2-pyroxene and garnet granulites, and hornblendites. The spinel and garnet websterites are interpreted as crystal segregations from olivine basalt or alkali olivine basalt magma at ∼ 12 kbar followed by isobaric cooling (to approximately 900–1000°C) and subsolidus reequilibration. Garnet and 2-pyroxene granulites are mineralogically and texturally distinct and are considered to represent relatively large degrees of crystallization of basaltic magmas at comparable or slightly lower pressures (8–12 kbar). Mafic and ultramafic xenoliths have been modified to varying degrees following the relatively recent influx of a H2O- and CO2-bearing fluid. Variable amounts of amphibole and mica developed in response to the introduced fluid and it is argued that some hornblendites are the end-products of this process acting on spinel websterites. Felsic and 2-pyroxene granulite xenoliths display only minor evidence of increased PH2O. Mineralogical and textural evidence indicates high-sulphur Ca-rich scapolite in several garnet granulites did not form in response to the increased fluid activities. It is proposed the scapolite was a primary cumulate phase precipitated from alkali basaltic magma under elevated fo2 and fso2 conditions.

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Sato-Okoshi, Waka, and Hirokazu Abe. "Morphology and molecular analysis of the 18S rRNA gene of oyster shell borers, Polydora species (Polychaeta: Spionidae), from Japan and Australia." Journal of the Marine Biological Association of the United Kingdom 93, no. 5 (January 23, 2013): 1279–86. http://dx.doi.org/10.1017/s002531541200152x.

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Nuclear 18S rRNA gene sequences of oyster shell borers, Polydora websteri, P. calcarea and P. haswelli (Polychaeta: Spionidae), were determined for the first time. A wide range of morphological variation, particularly with regard to pigmentation, is observed among these three species. This variation was characterized at the species level. Black pigmentation pattern on the palps is suggested to be a key characteristic for species determination. Polydora websteri and P. haswelli were sister species. This is the first record of P. calcarea from Japan and Australia and P. haswelli from Japan.

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Lu, Jianggu, William L. Griffin, Romain Tilhac, Qing Xiong, Jianping Zheng, and Suzanne Y. O’Reilly. "Tracking Deep Lithospheric Events with Garnet-Websterite Xenoliths from Southeastern Australia." Journal of Petrology 59, no. 5 (May 1, 2018): 901–30. http://dx.doi.org/10.1093/petrology/egy049.

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17

Chashchin, V. V., Y. E. Savchenko, and M. S. Lyulko. "Deep xenolith of platinum-bearing websterite from paleoproterozoic Volchetundra gabbro-anorthosite massif in the Kola region." Доклады Академии наук 486, no. 1 (May 10, 2019): 78–82. http://dx.doi.org/10.31857/s0869-5652486178-82.

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The results of studies of the deep platinum-bearing xenolith found in the Volchetundra gabbro-anorthosite massif of the Kola region are presented. It is shown that xenolith with a size of 8.5 × 4 m is composed of websterite in the central part and plagiowebsterite in the marginal. The chemical and mineral composition of xenolith rocks was studied. Information is given on the contents of noble and chalcophile elements in them, as well as the composition of platinum group minerals.

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Setiawan, Nugroho Imam, Kardo Polarman Rajoki Silitonga, Fahmi Adiyatma Makkaratte, and Chusni Ansori. "Determination of Scandium in mafic and ultramafic rocks of ophiolites from Luk Ulo Complex, Karangsambung, Central Java, Indonesia." E3S Web of Conferences 200 (2020): 06003. http://dx.doi.org/10.1051/e3sconf/202020006003.

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Scandium (Sc) is important element for its utilization in modern industry. Initial Sc content in the parent rocks primary importance controlling the Sc concentrations in its weathered derivatives. This contribution examines the Sc concentrations in parent rocks of mafic and ultramafic rocks related to the ophiolite series in Luk Ulo Complex, Karangsambung, Central Java, Indonesia. The ophiolite series in this area are basalt, microgabbronorite, gabbronorite, websterite, and serpentinite from 5 locations of Medana, Lokidang, Parakansubah, Selogiri, and Pucangan areas. The general trend from the distribution of Sc in the ophiolite sequence of Medana and Parakansubah-Lokidang Rivers suggests the Sc contents increase from shallow to deeper levels of the sequence. The lowest concentrations of Sc in the ophiolite sequence of Medana and Parakansubah-Lokidang Rivers are in basalt, which are 24–29 ppm. In the middle sequence, the Sc concentrations are 27–34 ppm and 24–43 ppm, respectively in microgabbronorite and gabbronorite. The highest Sc concentrations are in websterite, which are 51–54 ppm, as the deepest sequence of the ophiolite in this area. Meanwhile, Sc contents in serpentinite from Selogiri and Pucangan areas are 5–11 ppm, which are considered the lowest Sc contents. It suggests that the pre-serpentinization mineral composition rather than the process of serpentinization determine the elemental abundance of Sc in serpentinite. The results are used to be an analog for Sc identification in the ophiolite belts in central Indonesia. This also considering that Luk Ulo Complex been established as National Geopark of Karangsambung-Karangbolong, so that mining activities are prohibited in this area.

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Syomin, V. L., G. A. Kolyuchkina, M. D. Ptushkin, V. A. Timofeev, and U. V. Simakova. "POLYDORA WEBSTERI - A COMMENSAL OF ANADARA KAGOSHIMENSIS IN THE AZOV-BLACK SEA REGION." Russian Journal of Biological Invasions 14, no. 2 (June 11, 2021): 93–102. http://dx.doi.org/10.35885/1996-1499-2021-14-2-93-102.

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In January 2020, the presence of polychaete borers in the invader clam Anadara kagoshimensis (Tokunaga, 1906) was noted at the Chushka spit near Port Kavkas. Morphological analysis showed that the polychaetes belong to the species Polydora websteri Hartman in Loosanoff & Engle, 1943, non-indigenous to the Azov-Black Sea basin. This species was first recorded in coastal waters of Romania on carbonate rocks in 1997, followed by findings in 2009 and 2019 in coastal areas of Sevastopol and Lake Donuzlav, correspondingly, in oysters Crassostrea gigas (Thunberg, 1793). Polydora websteri has not previously been recorded from the Kerch Strait and the Sea of Azov. Its presence in Anadara kagoshimensis in the Azov-Black Sea region, which is an invasion area for both species, is shown for the first time.

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Rzedowski, Jerzy, Graciela Calderón de Rzedowski, and Emmanuel Pérez-Calix. "Tetrachyron omissum y Trigonospermum alexandri, dos especies nuevas de Compositae-heliantheae del centro de México." Acta Botanica Mexicana, no. 84 (July 1, 2008): 1. http://dx.doi.org/10.21829/abm84.2008.1063.

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Se describen como nuevas e ilustran Tetrachyron omissum y Trigonospermum alexandri. La primera habita en el noreste de Querétaro y es próxima a T. websteri (Wussow & Urbatsch) B. L. Turner. La segunda es una planta acuática o subacuática sólo conocida de un par de charcos cercanos a la población de Santa Clara del Cobre, en el norte de Michoacán. Posiblemente está emparentada con T. adenostemoides Less.Se describen como nuevas e ilustran Tetrachyron omissum y Trigonospermum alexandri. La primera habita en el noreste de Querétaro y es próxima a T. websteri (Wussow & Urbatsch) B. L. Turner. La segunda es una planta acuática o subacuática sólo conocida de un par de charcos cercanos a la población de Santa Clara del Cobre, en el norte de Michoacán. Posiblemente está emparentada con T. adenostemoides Less.

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21

Torres-Martínez, Miguel A., and Francisco Sour-Tovar. "New productide brachiopods (Productoidea) from the Carboniferous of Ixtaltepec Formation, Oaxaca, Mexico." Journal of Paleontology 90, no. 3 (May 2016): 418–32. http://dx.doi.org/10.1017/jpa.2016.54.

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AbstractFrom the Santiago Ixtaltepec area, in Oaxaca State, southern Mexico, 11 species of productoid brachiopods, including a new genus and five new species, are described.Semicostellasp.,Antiquatoniasp.,Keokukia? sp.,Inflatia inflata,Reticulatiacf.R.huecoensis,Buxtonia websteri,Weberproductus donajiaen. gen. n. sp.,Dictyoclostus transversumn. sp.,Inflatia coodzavuiin. sp.,Buxtonia inexpletucostan. sp., andFlexaria magnan. sp. were collected from eight stratigraphic levels of the Ixtaltepec Formation. The presence ofSemicostellasp.,Keokukia? sp. andInflatia inflatain the basal strata, Units 1 to 3, of the formation indicate a Viséan-Serpukhovian (Late Mississippian) age.Reticulatiacf.R.huecoensisandBuxtonia websteri, found in Units 6 to 8, confirm the Pennsylvanian age for upper strata of the Ixtaltepec Formation.InflatiaandFlexariaare present in the uppermost beds of the formation so it is possible to extend their upper stratigraphic range to the Middle Pennsylvanian. All these taxa also occur in the United States Midcontinent, suggesting that during the Carboniferous the epicontinental sea extended at least to central Mexico.

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22

Shearer, C. A., and J. L. Crane. "Boerlagiomyces websteri, a New Ascomycete from Fresh Water." Mycologia 87, no. 6 (November 1995): 876. http://dx.doi.org/10.2307/3760863.

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23

Shearer, C. A., and J. L. Crane. "Boerlagiomyces websteri, a new ascomycete from fresh water." Mycologia 87, no. 6 (November 1995): 876–79. http://dx.doi.org/10.1080/00275514.1995.12026608.

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24

Evans, B. W., S. M. Kuehner, and A. Chopelas. "Magnetite-free, yellow lizardite serpentinization of olivine websterite, Canyon Mountain complex, N.E. Oregon." American Mineralogist 94, no. 11-12 (November 1, 2009): 1731–34. http://dx.doi.org/10.2138/am.2009.3301.

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25

Yu, Xuehui, Xuanxue Mo, Zhongli Liao, Xin Zhao, and Qi Su. "Temperature and pressure condition of garnet lherzolite and websterite from west Qinling, China." Science in China Series D: Earth Sciences 44, S1 (December 2001): 155–61. http://dx.doi.org/10.1007/bf02911983.

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26

Maaløe, S. "The dunite bodies, websterite and orthopyroxenite dikes of the Leka ophiolite complex, Norway." Mineralogy and Petrology 85, no. 3-4 (August 3, 2005): 163–204. http://dx.doi.org/10.1007/s00710-005-0085-5.

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27

Spengler, Dirk, and Taisia A. Alifirova. "Formation of Siberian cratonic mantle websterites from high-Mg magmas." Lithos 326-327 (February 2019): 384–96. http://dx.doi.org/10.1016/j.lithos.2018.12.020.

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28

Wilson, A. H., and J. B. Chaumba. "Closed system fractionation in a large magma chamber: mineral compositions of the websterite layer and lower mafic succession of the Great Dyke, Zimbabwe." Mineralogical Magazine 61, no. 405 (April 1997): 153–73. http://dx.doi.org/10.1180/minmag.1997.061.405.01.

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AbstractThe Lower Mafic Succession of the Great Dyke is a 700 m thick sequence of gabbroic rocks which shows remarkably regular mineral compositional trends and trace element contents in whole rocks. Such chemical trends are strongly indicative of undisturbed fractionation having taken place within the magma chamber and contrast with the major development of cyclic units which characterize the underlying Ultramafic Sequence of the Great Dyke. The style of fractionation is quite different to that in the equivalent Main Zone of the Bushveld Complex with the latter possibly reflecting a ‘leaky’ input system, whereas in the Great Dyke the magma chamber was sealed. Major compositional reversals at the interface between the websterite layer (the topmost unit of the Ultramafic Sequence) and the base of the Lower Mafic Succession indicate a change in crystallization conditions at this level. Modal percentages of plagioclase and Al2O3 content of pyroxenes show the same trends indicating a strong control by temperature and magma composition.Modelling of the fractionation processes and the influence of trapped liquid was carried out for Mg#, Cr2O3, and NiO in pyroxenes and for Zr in whole rock. The lowermost gabbroic rocks are adcumulates with effectively zero trapped liquid which contrasts with 10–15% trapped liquid in the underlying websterite There is a gradual rise in the amount of trapped liquid upwards in the Lower Mafic Succession. These results have implications for the mechanisms by which porosity is reduced in mafic cumulates. An injection of a small amount (10%) of new magma at the interface of the Ultramafic-Mafic Sequences of the Great Dyke was of a composition slightly different to that which gave rise to the cyclic units of the Ultramafic Sequence.

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29

Tedonkenfack, Sylvin S. T., Jules Tamen, David G. Nkouathio, Bertrand T. Aziwo, Kagarabi P. Mulimbi, Yangouo F. Kimoun, Tabengo M. Ziada, and Sylvie N. F. Djukem. "Mantle Xenoliths from Ibal-Oku (Oku massif, North-west Region, Cameroon): Imprints of Superimposed Carbonatitic and Silicic Metasomatisms." Energy and Earth Science 3, no. 2 (October 29, 2020): p80. http://dx.doi.org/10.22158/ees.v3n2p80.

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Mantle xenoliths have been discovered in Ibal-Oku basalts from Oku Massif, Cameroon Volcanic Line. These xenoliths analyzed in term of major elements by scanning electron microscope, atomic emission spectrometry, traces and rare earth elements by mass spectrometry are peridotites and pyroxenites. Peridotites comprise Fe-rich lherzolites, harzburgites and wehrlites. Pyroxenites comprise websterites, olivine-websterites, clinopyroxenites and olivine-clinopyroxenites. Mineralogically, olivine Fo% values and NiO content vary from 85 to 91 and 0.26 to 0.43 wt.%, respectively. Orthopyroxene is enstatite, Mg# values and Al content ranging from 0.83 to 0.92 and 0.12 to 0.27 atom per formula unit (apfu), respectively. Clinopyroxene is augite and diopside, Mg# values and Al content ranging from 0.83 to 0.93 and 0.23 to 0.37 apfu, respectively. Spinel is aluminous, Cr# and Mg# values ranging from 0.07 to 0.23 and 0.67 to 0.82, respectively. Micas are biotites (Fe#: 0.52-0.76). Feldspars, which are secondary are sanidine, andesine and labradorite. Geochemically, peridotite Mg# values vary from 82.7 to 89.9 and pyroxenites from 80.1 to 83.6. The major element variations and some compatible elements are described in terms of partial melting (14-15 vol.% in lherzolites and 17-18 vol.% in harzburgites), whereas the heterogeneities in trace elements are related to carbonatitic/silicic metasomatism.

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30

Rehfeldt, Tatjana, Stephen F. Foley, Dorrit E. Jacob, Richard W. Carlson, and Dave Lowry. "Contrasting types of metasomatism in dunite, wehrlite and websterite xenoliths from Kimberley, South Africa." Geochimica et Cosmochimica Acta 72, no. 23 (December 2008): 5722–56. http://dx.doi.org/10.1016/j.gca.2008.08.020.

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31

Aulbach, Sonja, Thomas Stachel, Stephanus K. Viljoen, Gerhard P. Brey, and Jeff W. Harris. "Eclogitic and websteritic diamond sources beneath the Limpopo Belt – is slab-melting the link?" Contributions to Mineralogy and Petrology 143, no. 1 (2002): 56–70. http://dx.doi.org/10.1007/s00410-001-0331-8.

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32

Lisitskaya, E. V., and N. A. Boltachova. "About Regeneration of Alien Polychaete Polydora websteri (Annelida: Spionidae)." Russian Journal of Biological Invasions 12, no. 4 (October 2021): 355–61. http://dx.doi.org/10.1134/s2075111721040068.

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33

Gagné, Raymond J., and William M. Woods. "Native American Plant Hosts of Asphondylia websteri (Diptera: Cecidomyiidae)." Annals of the Entomological Society of America 81, no. 3 (May 1, 1988): 447–48. http://dx.doi.org/10.1093/aesa/81.3.447.

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34

Princivalle, F., A. Della Giusta, A. De Min, and E. M. Piccirillo. "Crystal chemistry and significance of cation ordering in Mg-Al rich spinels from high-grade hornfels (Predazzo-Monzoni, NE Italy)." Mineralogical Magazine 63, no. 2 (April 1999): 257–62. http://dx.doi.org/10.1180/minmag.1999.063.2.11.

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AbstractTwo Mg-Al spinels (FAS1 and FAS2) in high-grade hornfels from the Toal de Mason skarn (Predazzo Monzoni, NE Italy) were investigated by means of single crystal X-ray diffraction and electron microprobe analysis in order to evaluate the last intra-crystalline closure temperature.The evidence provided by crystal chemical data from the investigated spinels, compared with that for two other spinels from a websterite dyke and a chlorite schist (TS2 and SP78a, respectively) with similar chemical characteristics, yielded a new empirical geothermometer. This allowed estimation of intra-crystalline temperatures as low as c. 400°C and indicates that the closure temperature of FAS1 and FAS2 is c. 500°C i.e. 150–200°C lower than the spinel crystallisation temperature.

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35

Dantas, C., M. Grégoire, E. Koester, R. V. Conceição, and N. Rieck. "The lherzolite–websterite xenolith suite from Northern Patagonia (Argentina): Evidence of mantle–melt reaction processes." Lithos 107, no. 1-2 (January 2009): 107–20. http://dx.doi.org/10.1016/j.lithos.2008.06.012.

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36

Li, Xu-Ping, Hong-Kai Chen, Ze-Li Wang, Li-Jun Wang, Jing-Sui Yang, and Paul Robinson. "Spinel peridotite, olivine websterite and the textural evolution of the Purang ophiolite complex, western Tibet." Journal of Asian Earth Sciences 110 (October 2015): 55–71. http://dx.doi.org/10.1016/j.jseaes.2014.06.023.

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37

Rawson, J. R., D. A. Carswell, and D. Smallwood. "Garnet-bearing olivine-websterite within the Eastern Glenelg Lewisian of the Glenelg Inlier, NW Highlands." Scottish Journal of Geology 37, no. 1 (May 2001): 27–34. http://dx.doi.org/10.1144/sjg37010027.

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38

Hoddle, Mark S. "First Record of Asphondylia websteri (Diptera: Cecidomyiidae) Infesting Hass Avocados." Florida Entomologist 91, no. 3 (September 2008): 501–3. http://dx.doi.org/10.1653/0015-4040(2008)91[501:froawd]2.0.co;2.

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39

Musrifin, Laode, Hasria Hasria, and Ali Okto. "Karakteristik Batuan Dasar Pada Profil Nikel Laterit PT. Baula Petra Buana, Desa Roraya, Kecamatan Tinanggea, Kabupaten Konawe Selatan, Sulawesi Tenggara." OPHIOLITE : Jurnal Geologi Terapan 3, no. 2 (October 23, 2021): 102. http://dx.doi.org/10.56099/ophiolite.v3i2.23394.

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Daerah penelitian terletak di Desa Roraya, Kecamatan Tinanggea, Kabupaten Konawe Selatan, Sulawesi Tenggara. Tujuan penelitian ini yaitu untuk mengetahui karakteristik batuan dasar dan pengaruh batuan dasar terhadap kadar Ni dan Fe. Metode penelitian mencakup analisis kualitatif berupa survey geologi lapangan mencakup pengambilan data litologi dan data pengeboran eksplorasi PT. Baula Petra Buana, berupa data collar dan data assay. Berdasarkan hasil penelitian, batuan dasar daerah penelitian terdiri atas batuan peridotit (lerzolit dan werlit) dan batuan piroksenit (olivin websterit). Mineral penyusun batuan ini sebagian telah mengalami alterasi dalam bentuk rekahan yang terisi oleh serpentin. Sebaran kadar Ni paling banyak terdapat pada batuan dasar peridotit dibanding batuan dasar piroksenit. Peridotit lebih banyak mengandung olivin sebagai mineral pembawa unsur Ni dibanding piroksen. Pada profil laterit dengan batuan dasar peridotit, kadar Ni yang tinggi terakumulasi pada zona saprolit dan kadar Fe mengalami pengayaan residual pada zona limonit.

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40

Seitz, Hans-Michael, Rainer Altherr, and Thomas Ludwig. "Partitioning of transition elements between orthopyroxene and clinopyroxene in peridotitic and websteritic xenoliths: new empirical geothermometers." Geochimica et Cosmochimica Acta 63, no. 23-24 (December 1999): 3967–82. http://dx.doi.org/10.1016/s0016-7037(99)00163-5.

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41

Gagné, Raymond J., and G. M. Orphanides. "The pupa and larva of Asphondylia gennadii (Diptera: Cecidomyiidae) and taxonomic implications." Bulletin of Entomological Research 82, no. 3 (September 1992): 313–16. http://dx.doi.org/10.1017/s0007485300041079.

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AbstractPupae and larvae from various recorded hosts of the cecidomyiid Asphondylia gennadii (Marchal), a pest of carob on Cyprus, are found to be anatomically similar. These are redescribed and illustrated. The species appears to be a Palaearctic generalist species analogous to the Nearctic Asphondylia websteri Felt. Asphondylia capsici Barnes (Syn. n.) is considered a new junior synonym of A. gennadii. An unnamed soybean pod gall midge in Japan appears also to be identical to A. gennadii.

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42

Hoddle, Mark S. "Observations on Asphondylia websteri (Diptera: Cecidomyiidae) Infesting Hass Avocados in Guatemala." Florida Entomologist 92, no. 4 (December 1, 2009): 673. http://dx.doi.org/10.1653/024.092.0427.

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43

Taylor, Lawrence A., Gregory A. Snyder, Randall Keller, David A. Remley, Mahesh Anand, Rene Wiesli, John Valley, and Nikolai V. Sobolev. "Petrogenesis of group?A eclogites and websterites: evidence from the Obnazhennaya kimberlite, Yakutia." Contributions to Mineralogy and Petrology 145, no. 4 (July 1, 2003): 424–43. http://dx.doi.org/10.1007/s00410-003-0465-y.

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44

Tamura, Akihiro, Shoji Arai, Miyuki Takeuchi, Makoto Miura, and Tahmineh Pirnia. "Compositional heterogeneity of a websterite xenolith from Kurose, southwest Japan: insights into the evolution of lower crust beneath the Japan Arc." European Journal of Mineralogy 31, no. 1 (February 21, 2019): 35–47. http://dx.doi.org/10.1127/ejm/2018/0030-2803.

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45

Barnes, Stephen J., Reid R. Keays, and Dean M. Hoatson. "Distribution of sulphides and PGE within the porphyritic websterite zone of the Munni Munni Complex, Western Australia." Australian Journal of Earth Sciences 39, no. 3 (July 1992): 289–302. http://dx.doi.org/10.1080/08120099208728024.

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46

Snortum, Eric, James M. D. Day, and Matthew G. Jackson. "Pacific Lithosphere Evolution Inferred from Aitutaki Mantle Xenoliths." Journal of Petrology 60, no. 9 (September 1, 2019): 1753–72. http://dx.doi.org/10.1093/petrology/egz047.

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Abstract Highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, Re), major and trace element abundances, and 187Re–187Os systematics are reported for xenoliths and lavas from Aitutaki (Cook Islands), to investigate the composition of Pacific lithosphere. The xenolith suite comprises spinel-bearing lherzolites, dunite, and harzburgite, along with olivine websterite and pyroxenite. The xenoliths are hosted within nephelinite and alkali basalt volcanic rocks (187Os/188Os ∼0·1363 ± 13; 2SD; ΣHSE = 3–4 ppb). The volcanic host rocks are low-degree (2–5%) partial melts from the garnet stability field and an enriched mantle (EM) source. Pyroxenites have similar HSE abundances and Os isotope compositions (Al2O3 = 5·7–8·3 wt %; ΣHSE = 2–4 ppb; 187Os/187Os = 0·1263–0·1469) to the lavas. The pyroxenite and olivine websterite xenoliths directly formed from—or experienced extensive melt–rock interaction with—melts similar in composition to the volcanic rocks that host the xenoliths. Conversely, the Aitutaki lherzolites, harzburgites and dunites are similar in composition to abyssal peridotites with respect to their 187Os/188Os ratios (0·1264 ± 82), total HSE abundances (ΣHSE = 8–28 ppb) and major element abundances, forsterite contents (Fo89·9±1·2), and estimated extents of melt depletion (<10 to >15%). These peridotites are interpreted to sample relatively shallow Pacific mantle lithosphere that experienced limited melt–rock reaction and melting during ridge processes at ∼90 Ma. A survey of maximum time of rhenium depletion ages of Pacific mantle lithosphere from the Cook (Aitutaki ∼1·5 Ga), Austral (Tubuai’i ∼1·8 Ga), Samoan (Savai’i ∼1·5 Ga) and Hawaiian (Oa’hu ∼2 Ga) island groups shows that Mesoproterozoic to Neoproterozoic depletion ages are preserved in the xenolith suites. The variable timing and extent of mantle depletion preserved by the peridotites is, in some instances, superimposed by extensive and recent melt depletion as well as melt refertilization. Collectively, Pacific Ocean island mantle xenolith suites have similar distributions and variations of 187Os/188Os and HSE abundances to global abyssal peridotites. These observations indicate that Pacific mantle lithosphere is typical of oceanic lithosphere in general, and that this lithosphere is composed of peridotites that have experienced both recent melt depletion at ridges and prior and sometimes extensive melt depletion across several Wilson cycles spanning periods in excess of two billion years.

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47

Hinchliff, Cody E., Ariel Ernesto Lliully A., Timothy Carey, and Eric H. Roalson. "The origins of Eleocharis (Cyperaceae) and the status of Websteria , Egleria , and Chillania." TAXON 59, no. 3 (June 2010): 709–19. http://dx.doi.org/10.1002/tax.593004.

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48

Rice, LN, S. Lindsay, and P. Rawson. "Genetic homogeneity among geographically distant populations of the blister worm Polydora websteri." Aquaculture Environment Interactions 10 (October 11, 2018): 437–46. http://dx.doi.org/10.3354/aei00281.

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49

Sautter, Violaine, and Jacques Fabri�s. "Cooling kinetics of garnet websterites from the Freychin�de orogenic lherzolite massif, French Pyrenees." Contributions to Mineralogy and Petrology 105, no. 5 (October 1990): 533–49. http://dx.doi.org/10.1007/bf00302493.

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50

Lane, H. Richard, Qi Yuping, Wang Zhihao, Tamara I. Nemyrovska, Barry C. Richards, and Hu Keyi. "Conodonts from the mid-Carboniferous boundary GSSP at Arrow Canyon, Nevada, USA." Micropaleontology 65, no. 2 (2019): 77–104. http://dx.doi.org/10.47894/mpal.65.2.01.

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The Global Stratotype Section and Point of the mid-Carboniferous boundary was selected in the Arrow Canyon section within the lower Bird Spring Formation at the first evolutionary appearance of the conodont Declinognathodus noduliferus (Ellison and Graves) sensu lato. The studied boundary beds, spanning a 38.8-m interval from the Upper Mississippian into the Lower Pennsylvanian, occur in bryozoan-brachiopod-crinoidal grainstones/packstones with conodonts and foraminifers. The conodonts of the studied interval belong to the shallow-water Adetognathus-Rhachistognathus biofacies. The Adetognathus and Rhachistognathus species/subspecies A. lautus (=A. gigantus), A. spathus, R. minutus minutus, R. muricatus, R. primus, R. prolixus, R. websteri and transitional forms dominate the succession. Gnathodus girtyi simplex, G. lanei n. sp., G. defectus and transitional forms between them are abundant. The elements of the boundary-marker D. noduliferus s. l. and transitional forms between G. girtyi simplex and D. inaequalis are less common. The occurrences of Idiognathoides spp. are very rare. Neognathodus spp. only occur in the upper part of the studied interval. The mid- Carboniferous boundary stratotype has been studied by many workers but its conodonts have been rarely described systematically. The detailed updated descriptions of themost stratigraphically important taxa are given in this paper. The evolution of Gnathodus, Adetognathus and Rhachistognathus species within the midâ€“Carboniferous interval is discussed. Four lineages are summarized: 1) C. unicornis, A. unicornis, A. lautus and A. spathus; 2) G. girtyi girtyi, G. g. simplex and D. inaequalis; 3) G. lanei and G. defectus; and 4) R. prolixus, R. muricatus and R. websteri/R. primus/R. minutus.

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