Younger Series Research Articles

Reconstruction of Thermal Conditions in the Subboreal Inferred from Isotopic Studies of Groundwater and Calcareous Tufa from the Spring Mire Cupola in Wardzyń (Central Poland)

Studies with application of stable isotopes of oxygen and carbon have been performed on calcareous tufa, groundwater and dissolved inorganic carbon (DIC) from the spring mire cupola in Wardzyń. This study was focused on the verification of the a priori hypothesis that the analysed calcareous tufa is a chemical deposit and on the attempt to supplement an earlier scenario of environmental changes in the Subboreal with oscillations of water temperature. The constructed model of chemical and isotope balance, and δ13C determinations in DIC, allowed for calculating ratios of stable isotopes of carbon in particular speciations and in gaseous CO2. The obtained results coupled with δ13C values in calcite indicate that this mineral precipitated from the solution chemically (without the contribution of living organisms). Additionally, it was possible to reconstruct the temperature range at which the calcareous tufa was formed. The reconstructed scenario of changes in the thermal conditions was refined based on δ18O determinations in groundwater and calcite. Accordingly, the oldest calcareous tufa, with an age of about 5500 cal years BP, was formed in cool climate conditions (with average annual temperatures by about 3 °C lower than presently). The formation of younger series of the calcareous tufa took place between 4400–2900 cal years BP and represents a much warmer period with two distinct cooler episodes at 3900 and 3000 cal years BP, respectively. The course of the obtained temperature curves correlates well with the GISP2 curve and curves obtained for other sites in Northern, and Central Europe.

Mantle source heterogeneity in subduction zones: constraints from elemental and isotope (Sr, Nd, and Pb) data on Vulcano Island, Aeolian Archipelago, Italy

Vulcano is part of the Aeolian volcanic arc in the southern Tyrrhenian Sea. Its products were emplaced through multiple episodes of edifice building and collapse since about 120 ka B.P. to present. A major discontinuity in the activity occurred after about 28 ka, while the focus of volcanism moved from SE to NW. The older products are basalts to shoshonites, and have lower K2O than the younger ones, shoshonites to rhyolites. Between these two groups, Lentia latites-rhyolites, Spiaggia Lunga basalts, and Quadrara shoshonite-trachytes, erupted along the western side of Vulcano Island. The Spiaggia Lunga basalts (i) are the most primitive magmas erupted at Vulcano after 28 ka (ii) mark the change between older and younger phases, and (iii) overlap geochemically with a monzogabbroic intrusion of similar age. This work focuses on the Spiaggia Lunga products, discussed within a large dataset of geochemical and radiogenic isotope analyses on the entire Vulcano sequence. Older products have more primitive geochemical and isotope characteristics, and lower incompatible element contents, than younger ones. The Spiaggia Lunga basalts exhibit intermediate geochemical characteristics between the older and the younger groups, and can likely be regarded as a third magmatic phase, which represents a distinct mantle reservoir active during the magmatic history of Vulcano. Significant variations of Sr, Nd, and Pb isotope ratios, and isotopic disequilibrium between phenocrysts and groundmass, are present among the Vulcano products. This variability suggests crustal assimilation in shallow-level magma chambers, which also accounts for the formation of evolved products by combined assimilation and fractional crystallization, particularly in the younger series. Considering only the mafic products, incompatible element patterns with high LILE/HFSE and enriched signatures of Sr, Nd, and Pb isotope ratios, indicate enriched mantle sources. Besides, chemical and isotope variability among older, younger, and Spiaggia Lunga mafic rocks, suggests an origin from geochemically diverse primary melts, derived from distinct mantle reservoirs. Their parent magmas, based on geochemical and isotope patterns, were from both MORB- and OIB-type mantle sources, subject to variable degrees of metasomatism by subducted sediments.

Evolution of Early Pleistocene fluvial systems in central Poland prior to the first ice sheet advance – a case study from the Bełchatów lignite mine

Abstract Deposits formed between the Neogene/Pleistocene transition and into the Early Pleistocene have been studied, mainly on the basis of drillings and at rare, small outcrops in the lowland part of Polish territory. At the Bełchatów lignite mine (Kleszczów Graben, central Poland), one of the largest opencast pits in Europe, strata of this age have long been exposed in extensive outcrops. The present paper is based on our field studies and laboratory analyses, as well as on research data presented by other authors. For that reason, it can be seen as an overview of current knowledge of lowermost Pleistocene deposits at Bełchatów, where exploitation of the Quaternary overburden has just been completed. The results of cartographic work, sedimentological, mineralogical and palynological analyses as well as assessment of sand grain morphology have been considered. All of these studies have allowed the distinction of three Lower Pleistocene series, i.e., the Łękińsko, Faustynów and Krzaki series. These were laid down in fluvial environments between the end of the Pliocene up to the advance of the first Scandinavian ice sheet on central Poland. The following environmental features have been interpreted: phases of river incision and aggradation, changes of river channel patterns, source sediments for alluvia, rates of aeolian supply to rivers and roles of fluvial systems in morphological and geological development of the area. The two older series studied, i.e., Łękińsko and Faustynów, share common characteristics. They were formed by sinuous rivers in boreal forest and open forest environments. The Neogene substratum was the source of the alluvium. The younger series (Krzaki) formed mainly in a braided river setting, under conditions of progressive climatic cooling. Over time, a gradual increase of aeolian supply to the fluvial system can be noted; initially, silt and sand were laid down, followed by sand only during cold desert conditions. These fluvio-periglacial conditions are identified in the foreground of the advance of the oldest ice sheet into this part of central Poland. The series studied have been compared with other fluvial successions which accumulated in the Kleszczów Graben during subsequent glaciations so as to document general changes in fluvial systems as reactions to climatic evolution. Thus, a palaeoenvironmental scenario has emerged which could be considered to be characteristic of central Poland during the Early Pleistocene.

Petrologic and geochemical characterization of rift-related magmatism at the northernmost Main Ethiopian Rift: Implications for plume-lithosphere interaction and the evolution of rift mantle sources

In this paper, we present petrography, K–Ar ages, whole-rock major- and trace-element concentrations, and Sr–Nd–Hf–Pb isotopic ratios of volcanic rocks from Debre Birhan area in the northernmost Main Ethiopian Rift (MER). The K–Ar ages of the mafic series range from 27 to 0.25Ma, and two felsic rocks yield ages of 0.93 and 0.23Ma. The mafic volcanics are classified into older and younger series based on their K–Ar ages. The Mg-numbers (Mg#<60) of both mafic series, along with low Ni and Cr contents, clearly indicate that these lavas have undergone fractionation en route to the surface. Geochemical and isotopic compositions of the older and younger mafic lavas indicate that crustal contamination did not play a significant role in the evolution of their magmas, hence reflect the geochemical characteristics of the sources. The older and younger mafic volcanic rocks display contrasting trace element and isotopic signatures. The older lavas have higher La/Nb, Zr/Nb, Ba/Nb and 87Sr/86Sri (0.70445–0.70681) and lower ԐHf (−2.58 to +6.01) and ԐNd (−1.25 to +3.43) and less radiogenic Pb isotopic ratios (206Pb/204Pbi=17.82–18.64, except TG-54=19.1) relative to the younger mafic lavas. Correlations among isotopic ratios and trace element concentrations provide evidence for the involvement of at least three major end-member components (C-1, C-2, and C-3) in the petrogenesis of these mafic lavas. The C-1 end-member component contributes dominantly to younger mafic lavas, and has isotopic composition similar to the common component ‘C’ deduced from oceanic basalts. The second end-member component (C-2) is represented by lavas near the transition between older and younger, and has isotopic composition similar to that of the seafloor basalts of the Red Sea and the Gulf of Aden. The third end-member component (C-3) is prominent in the older mafic series, and similar isotopically to Pan-African lithosphere. The younger felsic volcanic rocks generally have higher 87Sr/86Sri (0.70395–0.70689) than younger mafic series (0.70366–0.70454) but Nd, Hf and Pb isotopic ratios similar to those of the younger mafic lavas. The element concentrations and Sr, Nd, Hf and Pb isotopic compositions of the younger felsic rocks are explained by fractional crystallization of mafic melts in shallow-level magma chambers accompanied by limited assimilation of crustal material. Low degrees of partial melting of existing mafic underplate can account for the genesis of the least-differentiated (intermediate) lavas, but failed to explain highly evolved younger felsic rocks.

Skunked!: Calpurnia Tate, Girl Vet by Jacqueline Kelly

Reviewed by: Skunked!: Calpurnia Tate, Girl Vet by Jacqueline Kelly Elizabeth Bush Kelly, Jacqueline Skunked!: Calpurnia Tate, Girl Vet; illus. by Teagan White. Holt, 2016 [112p] ISBN 978-1-62779-868-6 $15.99 Reviewed from galleys R Gr. 2-4 It’s not easy being a girl with a mind for science in a small Texas town at the dawn of the twentieth century. Nor is it easy being sole sister in a house full of brothers—particularly when younger brother Travis, who cannot resist turning a stray into a pet, relies on her for veterinary counsel when his husbandry skills inevitably go awry. Such is the seriocomic burden of Calpurnia Tate, late of Kelly’s older novels (The Evolution of Calpurnia Tate, BCCB 7/09, etc.) and now narrator of [End Page 133] an easy reader series, Calpurnia Tate, Girl Vet. It is unreasonable to expect Travis to leave a motherless skunk kit whimpering in a tree hole, and Callie understands that her role is to help him hide it from their disapproving family, keep it fed, and wrangle information from her naturalist grandfather and the town vet, Dr. Pritzker, as needed. When Travis discovers a second skunk, the runt of the abandoned litter, hanging on for dear life, Callie has to up her game, figuring out how to keep it supplied with hot bricks for warmth (a success), how to get milk down its tiny throat (another success), how to keep both the kits safe from the family dog (yet another success), and ultimately, how to save the teacher from getting sprayed by Stinky and Winky when Travis smuggles them into school (a sorry failure). Since it is unlikely that readers of Kelly’s novels will “read down” into this younger series, it is left to the adults familiar with Evolution and its sequel to appreciate how the author has retained the tone, humor, and family affection while paring plot down to a single well-structured, extended episode. Expect a fresh crop of Calpurnia readers to simply enjoy this on its own considerable merits. Final illustrations not seen. Copyright © 2016 The Board of Trustees of the University of Illinois

Human epidermal growth receptor-2 overexpressing early operable primary breast cancers in older (≥70 years) women: biology and clinical outcome in comparison with younger (

There is dearth of literature reporting the prevalence and biological characteristics as well as the long-term clinical outcome of human epidermal growth factor receptor-2 (HER2) overexpressing tumours in older women. Currently, research involving trastuzumab at large focuses on the younger population. This study aimed to analyse their biological characteristics and to compare them with their younger counterparts from a single centre with a long-term clinical follow-up. Over 37 years (1973-2010), 1758 older (≥70 years) women with early operable (<5 cm) primary breast cancer were managed in a dedicated clinic and have complete clinical information available. Of these, 813 patients underwent primary surgery and 575 had good quality tumour samples available for tissue microarray analysis using indirect immunohistochemistry. Comparison was made with data from a well-characterised younger (<70 years) series (N = 1711) treated between 1986 and 1998 (before adjuvant trastuzumab became standard) in our institution. Forty five (7.6%) and 140 (8.2%) patients from the older and younger series, respectively, had HER2-positive tumours. HER2 overexpression was seen in 45 (7.6%) older women and 140 (8.2%) in younger patients (P = 0.56). HER2 overexpressing tumours in older women when compared with that in their younger counterparts were associated with low Ki67 and high bcl2 expression (P < 0.05). Only 26% of the younger patients and none of the older patients received adjuvant chemotherapy, and no patients at the time received trastuzumab. However, there was no significant difference in the outcome of the two age groups (5-year breast cancer-specific survival rate: <70 years = 65% versus >70 years = 70%, P = 0.51). HER2 overexpressing tumours in older women showed relatively a less aggressive phenotype and did not show any inferior long-term clinical outcome despite not having received chemotherapy when compared with the younger patients. The precise role of different adjuvant systemic therapies in this population needs to be delineated.

Human epidermal growth receptor-2 overexpressing early operable primary breast cancers in older (≥70 years) women: Biology and clinical outcome in comparison with younger (&lt;70 years) patients.

e11608 Background: There is dearth of literature reporting the prevalence and biological characteristics as well as the long-term clinical outcome of HER2 positive tumors in older women. This study aimed to analyse their biological characteristics and compare them with their younger counterparts from a single centre with long-term clinical follow-up. Methods: Over 37 years (1973-2010), 1,758 older (≥70 years) women with early operable (&lt;5cm) primary breast cancer were managed in a dedicated clinic and have complete clinical information available. Of these 813 patients underwent primary surgery and 575 had good quality tumour samples available for tissue microarray (TMA) analysis using immunohistochemistry. Comparison was made with data from a well-characterised younger (&lt;70years) series (N=1,711) treated between1986 - 1998 (before adjuvant trastuzumab became standard) in our institution. Thirty-nine (7.6%) and 140 (8.2%) patients from the older and younger series respectively (p=0.56) had HER2-positive tumours. Results: See Table. Conclusions: The HER2 positive tumours in older women showed relatively less aggressive phenotype and did not show any inferior long-term clinical outcome despite not having received chemotherapy as compared to the younger patients. The precise role of different adjuvant systemic therapies in this population needs to be delineated. [Table: see text]

Snow Globe

Snow Globe Carl Phillips (bio) I Whatever falls is a thing descending. But descent doesn’t have to mean to fall. About nostalgia, I am still against it. By morning, there was no evidence of what had happened between us, or not happened. How everything depends. The sound of bees beginning to stir a last time all over again in the walls of a house left wintering. A little wind through the pines in stereo, making the limbs stiffly rise, like memorials, for those who choose to remember what’s over in that particular way, though I’ve never chosen it, and do not now. My requirements, they’re what they’ve always been: a name I can use when riding shotgun; then there’s my secret name. I’m not the man I knew. II And now the rain in soft strokes coming down, seeming to whisper of deaths that weren’t that heavenly after all, of lives cracked open first, gutted—some of us fuck and call it making love, for some it’s the other way round—then cast aside. You could do worse, and probably will, he says to me, I say to him, he says, and I say back. Even if the skitter of leaves in autumn can be called proverbial—if I’m not, for example, the man I knew—it is no less real, [End Page 341] any of it. Otherwise, what history have I got, with which to shadow us in context, lost ponies in a storm that’s blinding, blinding. It blinds us both. III I keep waiting for change, as opposed to the sign for change where it’s occurred already and I’m again too late. I keep pretending it makes no difference when the moon goes that do-what-you-must shade of red that there’s no real name for. As for how it feels, or can sometimes: like a life, like life itself, descending—sand cherry, chestnut, river birch, dogwood, pear . . . All night, I ride shotgun side by side with the ghost I call failure, for whom gesture, if not entirely the one language left, is the only one he still trusts, though there are times, even now, I forget this: he takes my hand, and I hold it— tight. And I turn my face away. IV Stumbling by moonlight upon your shadow-self—that man you knew, or thought you did—see if he stirs, first. Is he dead, or close to? If so, you could do worse than to stroke him as you would the brow of a broken pony, brushing away the flies that you choose to call, instead, bees as they ascend and hover slightly above the open wound, its red business . . . Why should your requirements change from what they’ve always been? Stay as blind as ever to the particular form of failure that is still nostalgia. Turn his face away. Let memory be the only piece of evidence that you hold onto. Not leaves, but—what is no less real—the ghosts of leaves. Do what you must, but softly, soft as rain just beginning to turn to snow at the cusp of winter.—Don’t worry. This, too, is love. [End Page 342] Carl Phillips Carl Phillips, a Chancellor of the Academy of American Poets and winner of the Kingsley Tufts Award, is author of over ten volumes of poems, including Double Shadow, Speak Low, Quiver of Arrows: Selected Poems 1986–2006, The Rest of Love, Rock Harbor, and The Tether. He is also author of Coin of the Realm: Essays on the Art and Life of Poetry and translator of Philoctetes, a tragedy by Sophocles. In addition to being inducted into the American Academy of Arts and Sciences, Phillips has also held fellowships from the Guggenheim Foundation, Academy of American Poets, and the Library of Congress. In 2010, he was appointed judge of the Yale Younger Series of Poets. He is Professor of English at Washington University in St. Louis, where he once served as Director of the Creative Writing Program. Copyright © 2012 The Johns Hopkins University Press

Evolution of shield-building and rejuvenescent volcanism of Mauritius

We report chemical and isotopic analyses of 68 samples and 40Ar/ 39Ar ages of 47 samples from Mauritius undertaken to understand the compositional evolution of the volcano and its causes through time. New 40Ar/ 39Ar ages show that construction of the Mauritius shield was well underway by 8.9 Ma, 1.1 m.y. earlier than previously thought and that the hiatus between the Intermediate and Younger Series was shorter than previously thought, as eruption of the rejuvenescent Intermediate Series continued through at least 1.66 Ma and Younger Series volcanism began by at least 1.0 Ma. Eruption frequency over the last 50 ka has been rather typical of Younger Series volcanism over the last 400 ka and future eruptions are possible. Although outcrops of the Intermediate Series lavas are confined to the Southwest, Intermediate Series are present beneath Younger Series flows in drill cores throughout the island. We estimate the total volume of rejuvenescent lavas at ~ 35 km 3 or about 0.05% of the volume of the volcano, similar to rejuvenescent volume fractions on Hawaiian volcanoes. As earlier studies found, Older Series lavas, which on average are slightly normatively silica-saturated, are somewhat more incompatible-element enriched than are the Intermediate and Younger Series, which are both slightly silica-undersaturated on average. Mean Sr and Nd isotope ratios of the Intermediate and Younger Series are nearly identical, but mean Pb isotope ratios, La/Sm, Nb/Y, and Nb/Zr of the Intermediate Series are higher than in the Younger Series. New high precision Pb isotope data, which shows considerably less scatter than previously published data, plot between the Older Series and basalts of the Central Indian Ridge, allowing the possibility that the source of the rejuvenescent lavas is a mixture of this plume and depleted mantle. We propose two possible explanations for the composition of rejuvenescent lavas. The first is that plume-derived melts reacted with deep lithosphere to form pyroxenite veins during the early shield-building stage. Later, these veins melted as a consequence of conductive heating of the lithosphere by the plume to produce the rejuvenescent lavas. Alternatively, rejuvenescent lavas may be derived from a sheath of thermally entrained mantle that surrounds the plume and is a mixture of plume material and depleted upper mantle.

New age data from the Dzirula massif, Georgia: Implications for the evolution of the Caucasian Variscides

The Caucasus mountain belt has a complex tectono-thermal history that is as yet poorly understood due to the scarcity of reliable geochronological information. Here, we report new monazite and zircon data from the Dzirula massif in the southern Caucasus, which permit development of a model for Variscan LP-HT (low pressure–high temperature) metamorphism in this region. Data are presented for two key lithologies of the Dzirula massif: 1) a group of variably deformed granitoid (mainly granodioritic-tonalitic) rocks and 2) metapelitic LP-HT cordierite-biotite-sillimanite migmatites and paragneisses. Electron-microprobe Th-U-total Pb monazite dating demonstrates that the LP-HT metamorphism in the Dzirula massif is Variscan, and occurred around 330 Ma. LA-ICP-MS zircon dating reveals that the granitoids include two different magmatic series. An older, mainly tonalitic, series is of Lower Cambrian age. Younger intrusions, including gabbros and diorites, but mainly tonalites and granodiorites, are Variscan in age. The older series show ductile deformation features and, along with the metapelites, experienced Variscan high-grade metamorphism that resulted in penetrative blastic recrystallization and anatexis. The younger series is generally undeformed, but often shows a magmatic foliation, and variable alteration under greenschist facies conditions. It is suggested that the Variscan intrusions facilitated the regional LP-HT metamorphic event at 330 to 340 Ma. Age and petrographic data from the Greater Caucasus imply a similar evolution as observed in the Dzirula massif. The Dzirula massif can thus be used as a proxy to model the evolution of the Caucasian Variscides.

Nonexplosive and explosive magma/wet-sediment interaction during emplacement of Eocene intrusions into Cretaceous to Eocene strata, Trans-Pecos igneous province, West Texas

Eocene intrusion of alkaline basaltic to trachyandesitic magmas into unlithified, Upper Cretaceous (Maastrichtian) to Eocene fluvial strata in part of the Trans-Pecos igneous province in West Texas produced an array of features recording both nonexplosive and explosive magma/wet-sediment interaction. Intrusive complexes with 40Ar/ 39Ar dates of ~ 47–46 Ma consist of coherent basalt, peperite, and disrupted sediment. Two of the complexes cutting Cretaceous strata contain masses of conglomerate derived from Eocene fluvial deposits that, at the onset of intrusive activity, would have been > 400–500 m above the present level of exposure. These intrusive complexes are inferred to be remnants of diatremes that fed maar volcanoes during an early stage of magmatism in this part of the Trans-Pecos province. Disrupted Cretaceous strata along diatreme margins record collapse of conduit walls during and after subsurface phreatomagmatic explosions. Eocene conglomerate slumped downward from higher levels during vent excavation. Coherent to pillowed basaltic intrusions emplaced at the close of explosive activity formed peperite within the conglomerate, within disrupted Cretaceous strata in the conduit walls, and within inferred remnants of the phreatomagmatic slurry that filled the vents during explosive volcanism. A younger series of intrusions with 40Ar/ 39Ar dates of ~ 42 Ma underwent nonexplosive interaction with Upper Cretaceous to Paleocene mud and sand. Dikes and sills show fluidal, billowed, quenched margins against the host strata, recording development of surface instabilities between magma and groundwater-rich sediment. Accentuation of billowed margins resulted in propagation of intrusive pillows into the adjacent sediment. More intense disruption and mingling of quenched magma with sediment locally produced fluidal and blocky peperite, but sufficient volumes of pore fluid were not heated rapidly enough to generate phreatomagmatic explosions. This work suggests that Trans-Pecos Texas may be an important locale for the study of subvolcanic phreatomagmatic processes and associated phenomena. Eocene intrusions in the study area underwent complex interactions with wet sediment at shallow levels beneath the surface in strata as old as Maastrichtian, which must have remained unlithified and rich in pore water for ~ 20–25 Ma.

Interobserver and Intraobserver Reliability of Detecting Age-related Macular Degeneration Using a Nonmydriatic Digital Camera

To evaluate the interobserver and intraobserver reliability of detecting early and late age-related macular degeneration (AMD) using a nonmydriatic digital camera in two distinct groups of older people. Prospective study. The two groups consisted of a series of patients older than 70 years hospitalized in a geriatric unit and a younger series of people older than 55 years. In both groups, nonmydriatic color fundus photographs were obtained and graded independently by two ophthalmologists (V.L. and M.S.). No ophthalmic examination was performed. Main outcome measures were frequencies of early and late AMD and interobserver and intraobserver agreement. Among 233 patients in group 1 (mean age, 84.6 years), only 119 patients (51%) could undergo photography because of associated multiple morbidities. Mean age of group 2 was 63.8 years. In group 1, 35 (14.5%) of 238 pictures were ungradable. In series 2, 65 (9.1%) of 716 pictures were ungradable. Frequencies of early and late AMD were 30.3% and 5.9% vs 12.6% and 2.6% in series 1 and 2, respectively. Interobserver and intraobserver agreement was good or excellent (kappa > 0.6) in both groups. In the entire geriatric cohort, 43% of the patients had gradable pictures allowing a diagnosis. These patients would otherwise have had no access to any form of funduscopy. In the younger population, nonmydriatic pictures permitted a diagnosis in 90% of the individuals. Detection of AMD with a nonmydriatic digital camera may lead to large-scale screening and specific management.

Compositional diversity among primitive lavas of Mauritius, Indian Ocean: Implications for mantle sources

Three distinct phases of basaltic volcanism (Older Series, 7.8–5.4 Ma; Intermediate Series, 3.5–1.9 Ma; Younger Series, 0.7–0.03 Ma), related to the Deccan–Réunion mantle–plume, occurred over a time span of nearly 8 million years on the island of Mauritius, Indian Ocean. Bulk rock compositions of 52 analyzed samples (including samples from 32 recent borehole sections), as well as the compositions of olivine and spinel phenocrysts, reveal significant temporal variations in the composition of the Mauritius magmas. Two distinct compositional groups are identified based on their major and trace element compositions. The Group 1 basalts comprise the Younger Series, Intermediate Series and the earlier products of the Older Series rocks, and have higher MgO (7.6–13.6 wt.%) and lower K 2O (0.2–0.5 wt.%) and La/Sm (2.1–3.5) compared to Group 2 basalts (MgO 6.2–9.2 wt.%; K 2O 1.0–1.5 wt.%; La/Sm 3.6–4.1), which exclusively encompass the later differentiation products erupted during the end of the Older Series volcanism, denoted as Older Differentiated (OD) Series. Petrographic and mineralogic studies further confirm the presence of two distinct groups. Relatively primitive olivine compositions (Fo: 87–80) in Group 1 rocks are characterized by increasing CaO (0.2 to 0.3 wt.%) with decreasing Fo content, whereas in Group 2 rocks olivine (Fo: 86–80) show decreasing CaO (0.4 to 0.3 wt.%) with decreasing Fo content. Olivine-hosted spinel inclusions also show strong compositional differences between groups 1 and 2. Unusually Al-rich spinels (compared to that usually found in plume derived magma) and the positive Sr anomalies in Group 1 rocks suggest assimilation of crustal gabbros by the plume magmas. We propose a laterally heterogeneous plume and the contributions from variable plume components to account for the compositional differences observed in the two Mauritian lava groups. The early-Shield building Older Series lavas (oldest Group1 lavas), characterized with a relatively less enriched trace element abundances, most likely derive from extensive melting of a depleted peridotite matrix in the core of the plume. Melting of this already depleted source produced the later Intermediate and Younger Series eruptions. Towards the late-shield stage, melts presumably derive from the enriched pyroxenite/eclogite components in the outer part of the plume.

The Eocene Rusayl Formation, Oman, carbonaceous rocks in calcareous shelf sediments: Environment of deposition, alteration and hydrocarbon potential

Paralic carbonaceous series intercalated among calcareous shelf sediments have seldom been investigated. During the early Eocene, calcareous and siliciclastic sediments were deposited on a wide shelf in front of low-reliefed hinterland in the Al Khawd region in NE Oman. The siliciclastic-calcareous sediments originated from strongly reworked debris of the Arabic Shield. The underlying Semail Ophiolite did not act as a direct source of debris but provided some heat to increase the maturity of carbonaceous rocks and modify the isotope signal of the calcareous minerals in the Rusayl Formation. A multidisciplinary approach involving sedimentology, mineralogy, chemistry, coal petrography and paleontology resulted in the establishment of nine stratigraphic lithofacies units and provides the reader with a full picture from deposition of the mixed carbonaceous-calcareous-siliciclastic rocks to the most recent stages of post-depositional alteration of the Paleogene formations. The calcareous Jafnayn Formation (lithofacies unit 1) developed in a subtidal to intertidal regime, influenced episodically by storms. Deepening of the calcareous shelf towards younger series was ground to a halt by paleosols developing on a disconformity (lithofacies unit 11) and heralding the onset of the Rusayl Formation. The stratigraphic lithofacies units III and IV reflect mangrove swamps which from time to time were flooded through washover fans from the open sea. The presence of Spinozonocolpites and the taxon Avicennia, which today belong to a coastal marsh vegetational community, furnish palynological evidence to the idea of extensive mangrove swamps in the Rusayl Formation [El Beialy, S.Y., 1998. Stratigraphic and palaeonenvironmental significance of Eocene palynomorphs from the Rusayl Shale Formation, Al Khawd, northern Oman. Review of Palaeobotany and Palynology 102, 249-258]. During the upper Rusayl Formation (lithofacies units V through VII) algal mats episodically flooded by marine incursions make up a greater deal of the sedimentary record than mangrove swamps. Terra rossa paleosols mark the end of accumulation of organic material (OM) and herald supratidal conditions at the passage of Rusayl Formation into the overlying Seeb Formation. In the subtidal-supratidal cycles of lithofacies unit VIII the terra rossa horizons are thining upwards and become gradually substituted for by deep-water middle ramp sediments of lithofacies unit IX Framboidal pyrite, (ferroan) dolomite with very little siderite are indicative of an early diagenetic alteration stage I under rather moderate temperatures of formation.

Foreword

Abstract The natural products theme is deeply rooted in the culture of IUPAC, and the first International Symposium on the Chemistry of Natural Products (ISCNP) on 15-25 August 1960 with Sir Alexander Todd (later, Lord Todd) as President, can claim particular credit in the history of the Union. Not only did it take an early bold step toward the truly global reach that characterizes IUPAC conferences in the modern era, but it was the harbinger of numerous sponsored or Union-initiated series devoted to other areas of specialization in the chemical sciences. International delegates to the inaugural event undertook the then nontrivial journey to Melbourne, Canberra, and Sydney, Australia with an excursion to New Guinea, to participate in a scientific program, in which structural elucidation and synthesis were dominant themes, and most familiar modern tools and techniques were still in their infancy. Natural products lore still celebrates the names of certain pioneers who contributed to that first program. As a series, this hardy biennial has since been hosted throughout the world, and has faithfully served a huge international community of scientists engaged in every conceivable aspect of natural products chemistry. The terms of reference for the ISCNP series have recently been adapted following a decision to merge with the younger series of International Conferences on Biodiversity (ICOB). This step was inaugurated with ISCNP-24/ICOB-4, which was held in New Delhi, India on 26-31 January 2004; &amp;lt;http://www.iupac.org/publications/pac/2005/7701/index.html&amp;gt;. The change exemplifies the evolving nature of the subject, and its ongoing appeal to scientists engaged in exploring and developing less familiar disciplinary interfaces, as well as traditional mainstream areas. It is thus unsurprising that natural products should feature as a Special Topic theme for a second time in the recent history of Pure and Applied Chemistry (PAC); see &amp;lt;http://www.iupac.org/publications/pac/2003/7502/ index.html&amp;gt; for a collection of papers based upon presentations at ISCNP-23, held in Florence, Italy on 28 July-02 August 2002. That program featured fresh insights into proteomics, genetics, and molecular biology, in a trend that ISCNP-25/ICOB-5 has continued to develop, with coverage of related and new features of bioactivity at the molecular level and chemical biological themes, whilst also paying homage to enduring favorites such as structure and synthesis. What is a Special Topic? The concept was introduced as a device to publicize and promote new and emerging principles and practice in all branches of chemical sciences, through the pages of PAC; &amp;lt;http://www.iupac.org/publications/pac/index.html#si&amp;gt;. Themes may be selected from inaugural events or special IUPAC projects, but equally, may identify themselves as dynamic and widely practiced areas of science presently covered by regular IUPAC-sponsored series. Important criteria obviously include relevance, topicality, and readership expectations. Publication projects arising from the Special Topics initiative generally continue to achieve gratifyingly favourable citation profiles, and thereby support the view that they fulfil an important need. It is noteworthy that the Kyoto meeting represents the third occasion that the series has been hosted in Japan, the home of some quite extraordinary manifestations of natural products and biodiversity, as well as some of the outstanding practitioners of the subject. The program of ISCNP-25/ICOB-5 rightly captures some of this local character, but is also a fully representative expression of the international participation and appeal that traditionally characterizes the series. It is a pleasure to acknowledge the able and enthusiastic support of the Conference Editor, Prof. Hideo Kigoshi, in preparing this Special Topic issue of 27 topical papers based upon program presentations. The collection aspires to offer an enduring archival record of a subject that continues to reinvent itself, and to astound and challenge its practitioners with the apparently boundless molecular riches of the biosphere. James R. Bull Scientific Editor

Petrology and geochemistry of augite trachytes and porphyritic trachytes from the Gölcük volcanic region, Isparta, SW Turkey: A case study

The Plio-Quaternary alkaline volcanic rocks at Gölcük, Isparta, SW Turkey, include older porphyritic trachytes, augite trachytes and younger trachyandesitic and tephriphonolitic dikes. In order to better understand their pre-eruptive evolution the geochemical variations of porphyritic trachytes and augite trachytes have been modeled quantitatively using the MELTS algorithm ( Ghiorso and Sack, 1995). Their geochemical variations are also compared with those of the younger series. Results show that two distinct magma series (trachyte-trachyandesite and tephriphonolite) governed the petrogenesis of Gölcük volcanic rocks. Geochemistry of the trachytic-trachyandesitic series is controlled predominantly by clinopyroxene and plagioclase fractionation at a shallow depth under oxygen fugacity conditions, two units above the QFM buffer. MELTS calculations also show that the crystallisation of trachytic-trachyandesitic magma produces clinopyroxene, plagioclase, alkali feldspar, biotite, apatite and magnetite+quartz, consistent with the mineralogy of the augite trachyte, porphyritic trachyte and trachyandesitic dikes.

Geochemistry of Mauritius and the origin of rejuvenescent volcanism on oceanic island volcanoes

We report new trace element concentrations and Sr, Nd, Hf, and Pb isotopic ratios for basalts from the three lava series of Mauritius. Older Series lavas, which represent the shield‐building phase of Mauritius, are isotopically similar to other lavas produced by the Réunion mantle plume. The Intermediate and Younger Series lavas, erupted after a hiatus of millions of years, have more depleted isotopic signatures than the Older Series. Incompatible element abundances and major element compositions suggest that the extent of melting was greatest for the Older Series, smallest for the Intermediate Series, and intermediate for the Younger Series. Volcanic evolution on Mauritius is thus broadly similar to the Hawaiian pattern, with lavas of the rejuvenescent phase being produced by small degrees of melting of a more depleted source than the shield phase. We propose that both shield and rejuvenescent phase magmas are derived from a lithologically heterogeneous or “plum pudding” mantle plume that consists of pods or veins of low‐solidus‐temperature material such as eclogite or pyroxenite embedded in peridotite matrix. The plums have a less depleted isotopic signature than the matrix. In the vertical stem of the plume, melting is zoned: at greatest depth, only the plums melt; at intermediate depth, both plums and matrix melt, and at shallowest depth, only the matrix melts. Shield stage magmas are hybrids of melts produced in all three zones. As the plume flattens out against the lithosphere and is dragged downstream of the stem, some melting continues due to buoyant lateral spreading of the plume. In this region, although both plums and matrix are melting, melts produced carry the isotopic signature of the matrix because incompatible elements in the plums were previously stripped during melting in the vertical stem of the plume. The relatively small degree melts produced in the melting tail, which give rise to rejuvenescent stage volcanism, thus carry the isotopic signature of the matrix. From a consideration of thermal and isotopic equilibrium, we judge the scale of heterogeneity to be about 102 m.

Systematic Variation of Sr-, Nd- and Pb-Isotopes with Time in Lavas of Mauritius, Reunion Hotspot

We report Sr-, Nd- and Pb-isotopic compositions for the lavas of Mauritius, the second youngest volcanic island in the Reunion hotspot. The lavas of the Older Series (7·8–5·5 Ma) have identical isotopic compositions (87Sr/86Sr = 0·70411 to 0·70422,143Nd/144Nd = 0·512865 to 0·512854, and 206Pb/204Pb = 19·016 to 19·041) to those of Reunion, where the center of volcanic activity is currently located. The lavas of the Intermediate Series (3·5–1·9 Ma) and Younger Series (0·70–0·17 Ma) are shifted to lower Sr-isotopic compositions (0·70364–0·70394, with 143Nd/144Nd = 0·512813 to 0·512948 and 206Pb/204Pb = 18·794 to 18·984). The Intermediate Series lavas have similar trace-element characteristics (e.g. Zr–Nb, Ba–Y) to those of Rodrigues, in both cases requiring the involvement of an enriched mantle-like component in the mantle source. During the volcanic history of Mauritius, the magmas lost the principal isotopic characteristics of the Reunion hotspot with time, and became gradually imprinted with the isotopic signature of a shallower mantle source that produced the Central Indian Ridge basalts.

A detailed palaeomagnetic study of the oldest (≈15 Myr) lava sequences in Northwest Iceland

SUMMARY We have determined the directions of primary remanence in over 400 lava flows in the northwestern peninsula of Iceland (near 66.1°N, 23.3°W). These lavas were sampled in 16 profiles spread across 75 km, at the stratigraphic level of the oldest (approximately 15 Myr in age) of several distinctive lignite-bearing sediments in the peninsula. We find that the pattern of polarity reversals in the lava pile is broadly similar in these profiles but it is generally not possible to trace short polarity zones and excursions over more than a few kilometres laterally. Our results, which also include measurements on the lignite sediments at three sites, are consistent with previous suggestions that these sediment beds represent a time gap of the order of 0.2 Myr between the lavas above and below. The mean virtual geomagnetic pole of this collection is ‘far-sided’ by approximately 7°, and the scatter of individual poles is greater than that in palaeomagnetic surveys on younger lava series in Iceland.

Geochemistry of Lavas from Mauritius, Indian Ocean: Mantle Sources and Petrogenesis

Trace-element and Nd-Sr-Pb isotopic data for mafic lavas from the Mascarene island of Mauritius reveal that the shield-stage Older Series (with 143Nd/144Nd = 0.512827 to 0.512853, 87Sr/86Sr = 0.70412 to 0.70433, and 206Pb/204Pb = 18.771 to 19.024) is geochemically very similar to the shield-building lavas of the younger island of Réunion. The post-shield Intermediate and Younger Series lavas of Mauritius have systematically greater values of 143Nd/144Nd and lower 87Sr/86Sr ratios than the Older Series and Réunion lavas. Intermediate and Younger Series Nd and Sr isotopic ratios are closely similar (0.512874 to 0.512899; 0.70369 to 0.70401), whereas 206Pb/204Pb ranges from values as great as any for the Older Series and Réunion lavas to as low as 18.608. Most of the Intermediate Series lavas are strongly enriched in highly incompatible elements relative to moderately incompatible ones (e.g., chondrite-normalized La/Lu = 4.03-17.8 vs. 9.38-10.2 for the Older Series), but the Younger Series lavas display much less relative enrichment (e.g., chondrite-normalized La/Lu = 3.86-5.37) and have low concentrations of incompatible elements. Modeling suggests that variable partial melting and mixing between mid-ocean-ridge-basalt (MORB) source mantle and mantle with bulk-Earth-like Nd and Sr isotopic and incompatible-element ratios, and "C"-like Pb isotope ratios, can explain the general relationship between the shield and post-shield lavas. All Mauritius and Réunion lavas can be explained as 2-8% partial melts of a bulk-Earth-like source that had been 1.5-0.25% metasomatized by a 0.1% MORB-source melt. The range in Pb isotopic compositions requires mixing with highly variable Sr/Pb and Nd/Pb ratios in the end members; such variation, however, is not supported by measured Sr/Pb, Nd/Pb, etc. in the lavas. Some isotopic heterogeneity thus appears to be required in the end members and/or much of the range in Pb isotopes represents radiogenic ingrowth since the metasomatic event. Near-constant 207Pb/204Pb values over the range of 206Pb204Pb among the Older Series lavas suggest that the metasomatic event must have occurred within the last few hundred million years.