Description: In a consortium including 23 637 breast cancer patients and 25 579 controls of East Asian ancestry, we investigated 70 single-nucleotide polymorphisms (SNPs) in 67 independent breast cancer susceptibility loci recently identified by genome-wide association studies (GWASs) conducted primarily in European-ancestry populations. SNPs in 31 loci showed an association with breast cancer risk at P 〈 0.05 in a direction consistent with that reported previously. Twenty-one of them remained statistically significant after adjusting for multiple comparisons with the Bonferroni-corrected significance level of 〈0.0015. Eight of the 70 SNPs showed a significantly different association with breast cancer risk by estrogen receptor (ER) status at P 〈 0.05. With the exception of rs2046210 at 6q25.1, the seven other SNPs showed a stronger association with ER-positive than ER-negative cancer. This study replicated all five genetic risk variants initially identified in Asians and provided evidence for associations of breast cancer risk in the East Asian population with nearly half of the genetic risk variants initially reported in GWASs conducted in European descendants. Taken together, these common genetic risk variants explain ~10% of excess familial risk of breast cancer in Asian populations.

Description: The Marginal Border Series of the Skaergaard intrusion (East Greenland) crystallized in situ on the vertical walls of the magma chamber. It is subdivided into an outer Unbanded Division and an inner Banded Division. The Banded Division contains abundant centimetre- to decimetre-thick bands dominated by fine-grained mafic minerals, with a morphology evolving from almost planar to deeply scalloped and fingered with increasing distance from the intrusion margin. The morphology of these bands is reminiscent of the reaction fronts described in sedimentary basins infiltrated by reactive fluids. We propose that the banding in the Skaergaard Marginal Border Series is produced by chemical disequilibrium resulting from the suction of primitive liquid from the main magma body into the crystal mush, driven by shrinkage of the mush during solidification. Liquid porous flow results in partial dissolution of evolved pre-existing mafic minerals in the mush. This changes the mush liquid composition to one capable of crystallizing mafic rocks with a very minor plagioclase component. Abrupt solidification of this liquid, resulting in the formation of the colloform bands, is explained by supersaturation of some mafic mineral components (e.g. olivine, clinopyroxene, Fe–Ti oxides) in the infiltrating melt. We suggest that the morphological evolution of the colloform bands is a consequence of increasing crystal mush thickness with progressive differentiation.

Description: New compositional profiles across plagioclase grains from the Layered Series (LS), Marginal Border Series (MBS) and Upper Border Series (UBS) of the Skaergaard intrusion are used to understand the mechanisms of cumulate rock solidification and the fate of the interstitial liquid. The data show that plagioclase crystals display three types of compositional profile over the whole intrusion, as follows. (1) Grains with normal zoning, which dominate the MBS and UBS. These are interpreted as having formed at the top of a crystal mush and then buried in the cumulate pile. Crystallization of the interstitial melt resulted in liquid differentiation and produced normally zoned rims on plagioclase cores. (2) Unzoned crystals, which dominate the upper part of the LS, also crystallized at the top of the mush and were then buried in mush with a low interstitial liquid fraction or one experiencing convective movements that kept the liquid to a constant composition. (3) Crystals with a mantle of decreasing An content followed by a rim of constant composition. Grains showing this complex zoning mostly occur in the lower parts of the LS. Depending on the stratigraphic position within the intrusion, the composition of the rim can be An 56 , An 51 or An 40 . In the main magma body, these compositions (An contents) correspond to those of plagioclase primocrysts (e.g. cores) at the appearance of cumulus clinopyroxene (An 56 ), Fe–Ti oxides (An 51 ) and apatite (An 40 ). Compositional buffering of plagioclase rims is interpreted as being a consequence of enhanced release of latent heat of crystallization at the appearance of new interstitial phases in the crystal mush. When a new phase saturates, the latent heat contribution to the global enthalpy budget of the system becomes sufficiently high to keep the interstitial melt at its liquidus temperature for a period of time that could exceed thousands of years. Under these conditions, equilibrium, adcumulus growth together with diffusion and possibly advection of chemical components result in the formation of plagioclase rims of constant composition (An content). Efficient thermal buffering of the mush liquid depends on the porosity (i.e. fraction of liquid within the mush) and the degree of compositional homogeneity of the mush. In a heterogeneous and highly porous mush, saturation of the new phase occurs in the coldest part of the mush and the enhanced latent heat release at the saturation of this phase is quickly dissipated to the whole volume of liquid, including the warmest part that is not yet saturated in a new phase. As a consequence, no thermal buffering occurs and interstitial crystallization produces grains with normal zoning. The distribution of the various types of plagioclase grains throughout the Skaergaard intrusion can therefore be used to infer the spatial variability in the physical properties of the crystal mush, such as the residual porosity, both at an intrusion-wide scale and at a millimetre- to centimetre-scale.

Description: Equilibrium crystallization experiments have been performed on a primitive high-MgO basalt (HMB) from Soufrière, St. Vincent, with three initial H 2 O contents (0·6, 2·3 and 4·5 wt %), at pressures of 0·4, 0·7, 1·0 and 1·3 GPa and temperatures from 1350 to 950°C. Redox conditions, as determined by µXANES analysis of Fe 3+ in experimental glasses, were 1–4 log units above the nickel–nickel oxide (NNO) buffer. The aim of the study was to explore the differentiation conditions that gave rise to the observed geochemical variation in lavas and plutonic (cumulate) xenoliths from St. Vincent. An experiment with 4·5 wt % initial H 2 O is multiply saturated close to its liquidus (1180°C and 1·3 GPa) with a spinel lherzolite assemblage, which is consistent with a primary origin for HMB in the mantle wedge. Multiple saturation of HMB with 2·3 wt % H 2 O was not observed, but is inferred to occur at pressures 〉1·3 GPa. The experimental results show that initial H 2 O content has significant influence on differentiation paths of primary HMB magma, with different lava varieties generated under discrete, well-constrained P–T–H 2 O conditions. Low-magnesian basalts (LMB) can be generated from HMB with 2·3–4·5 wt % H 2 O at pressures of 1·0–1·3 GPa, corresponding to Moho depths beneath St. Vincent. The CaO contents of LMB are sensitive to differentiation pressure: high-CaO LMB are produced at pressures 〉0·5 GPa. Basaltic andesites (BA) can be generated at 0·7–1·0 GPa from HMB with 0·6–2·3 wt % H 2 O. High-alumina basalts (HAB) are produced at mid- to upper-crustal conditions (≤0·4 GPa) by differentiation of HMB with high initial H 2 O (≥4 wt %) through delay of plagioclase crystallization and dominant fractionation of olivine, clinopyroxene and spinel. St. Vincent andesites could be produced from relatively dry (≤0·6 wt % H 2 O) HMB only at lower-crustal conditions. This is suggestive of a partial melting origin from precursor HMB that had solidified at depth to produce gabbros with ~30% hornblende (i.e. ~0·6 wt % structurally bound H 2 O). The experimentally determined differentiation conditions are consistent with polybaric differentiation within a hot zone that extends from the Moho and uppermost mantle to the mid- or upper crust. Within the hot zone differentiation occurs by a combination of crystallization of HMB with 2–5 wt % H 2 O and partial melting of ancestral HMB gabbros. Although the experimental melts provide an excellent match to erupted lava compositions, experimental crystal compositions do not match either phenocrysts or cumulate crystals, as preserved in xenoliths. The failure to reproduce natural crystal compositions suggests that these are formed as differentiated magmas ascend and attain their H 2 O-saturated liquidi at shallower pressures. Thus there is a disconnect between the high-pressure phase compositions and assemblages that generate liquid compositional diversity and the low-pressure composition and assemblages that occur as phenocrysts and in cumulate xenoliths. This finding lends support to the idea of cryptic fractionation in the generation of arc magmas.

Description: Arc magmas erupted at the Earth’s surface are commonly more oxidized than those produced at mid-ocean ridges. Possible explanations for this high oxidation state are that the transfer of fluids during the subduction process results in direct oxidation of the sub-arc mantle wedge, or that oxidation is caused by the effect of later crustal processes, including protracted fractionation and degassing of volatile-rich magmas. This study sets out to investigate the effect of disequilibrium crustal processes that may involve coupled changes in H 2 O content and Fe oxidation state, by examining the degassing and hydration of sulphur-free rhyolites. We show that experimentally hydrated melts record strong increases in Fe 3+ /Fe with increasing H 2 O concentration as a result of changes in water activity. This is relevant for the passage of H 2 O-undersaturated melts from the deep crust towards shallow crustal storage regions, and raises the possibility that vertical variations in f O 2 might develop within arc crust. Conversely, degassing experiments produce an increase in Fe 3+ /Fe with decreasing H 2 O concentration. In this case the oxidation is explained by loss of H 2 as well as H 2 O into bubbles during decompression, consistent with thermodynamic modelling, and is relevant for magmas undergoing shallow degassing en route to the surface. We discuss these results in the context of the possible controls on f O 2 during the generation, storage and ascent of magmas in arc settings, in particular considering the timescales of equilibration relative to observation as this affects the quality of the petrological record of magmatic f O 2 .

Description: The Tertiary Skaergaard intrusion, East Greenland, intruded at the shallow crustal unconformity between Precambrian amphibolite-facies gneisses and overlying Tertiary Plateau Basalts. Maximum contact metamorphic temperatures in quartzo-feldspathic gneisses were determined in two sample traverses across the aureole on the western contact of the intrusion using a combination of microstructural observations (both optical and cathodoluminescence) and the titanium-in-quartz (TitaniQ) thermometer. The onset of recrystallization of the quartz in the gneisses occurred between 390 and 340 m from the contact whereas H 2 O-fluxed melting occurred in gneisses closer than 130 m from the contact (where T 〉 ~ 675°C). The maximum temperature recorded by quartz at the contact is ~865 ± 70°C. Melt fractions reach 50–60 vol. % in some samples although the melt is heterogeneously distributed on all scales. Minor bands of amphibolite-facies mafic gneiss are extensively reacted to an anhydrous pyroxene-bearing hornfels close to the contact, whereas those further than ~130 m are overprinted by a greenschist-facies assemblage. Discrepancies between the expected temperature for the amphibolite- to greenschist-facies reaction and temperatures obtained from adjacent quartzo-feldspathic gneisses are consistent with the formation of the anhydrous pyroxene hornfels directly from the mafic gneiss, with the lower-grade greenschist-facies assemblage forming on the retrograde path after the establishment of limited hydrothermal activity. It is unlikely that devolatilization reactions in the gneiss produced sufficient H 2 O to account for the pegmatitic features formed in the Marginal Border Series in the intrusion. A simple one-dimensional thermal model, neglecting any advection of heat by hydrothermal circulation, was fitted to the profile of maximum temperature through the aureole. The generally lower temperatures seen in the gneiss compared with those previously reported for the contact metamorphosed basalts higher up the walls of the intrusion are consistent with a heterogeneous release of latent heat of crystallization.

Description: Mt. Lamington is a composite, dome-forming volcano in Papua New Guinea, sitting on the Papuan Ultramafic Belt (PUB) ophiolite. The 1951 eruption produced andesitic dome lavas with numerous basaltic–andesitic enclaves and a few PUB ultramafic xenoliths. To understand the nature of the 1951 eruption, and to assess the effect of assimilating ophiolitic crust in modifying the geochemistry of arc magmas, we carried out petrological, mineralogical and geochemical studies on andesitic lavas as well as magmatic enclaves and ultramafic inclusions. The mineralogy of the enclaves is dominated by amphibole and plagioclase, similar to the andesitic lava hosts. The textures of the enclaves vary from fine-grained diktytaxitic to coarser-grained plutonic textured. We interpret this variation to result from variable cooling rates in the enclave-forming magma body when it invades the overlying andesite. The diktytaxitic enclaves contain variable proportions of host-derived amph + plag antecrysts and xenocrysts of ol + sp ± cpx ± amph with disequilibrium textures, indicating interaction with host lava and assimilation of foreign materials, respectively. A previous study argued that the olivine xenocrysts with chromian spinel inclusions are derived from the PUB, and thus that the PUB contaminated the Mt. Lamington magmas. We demonstrate that this is highly unlikely on the basis of morphological and compositional discrepancies between PUB ol + sp, sampled in nodules, and the xenocrysts. Mass balance indicates that the high whole-rock Ni contents of enclaves and andesitic hosts can be explained by olivine incorporation and do not require any PUB involvement. The olivines are considered to represent crystal mush fractionated from precursor(s) of andesitic and/or pre-1951 shoshonitic lavas. Their presence in enclaves represents recycling of earlier-fractionated components through magma recharge. We argue that this recycling is an important and underestimated process in shaping arc magmas.

Description: Recent genome-wide association studies identified 11 single nucleotide polymorphisms (SNPs) associated with breast cancer (BC) risk. We investigated these and 62 other SNPs for their prognostic relevance. Confirmed BC risk SNPs rs17468277 ( CASP8 ), rs1982073 ( TGFB1 ), rs2981582 ( FGFR2 ), rs13281615 (8q24), rs3817198 ( LSP1 ), rs889312 ( MAP3K1 ), rs3803662 ( TOX3 ), rs13387042 (2q35), rs4973768 ( SLC4A7 ), rs6504950 ( COX11 ) and rs10941679 (5p12) were genotyped for 25 853 BC patients with the available follow-up; 62 other SNPs, which have been suggested as BC risk SNPs by a GWAS or as candidate SNPs from individual studies, were genotyped for replication purposes in subsets of these patients. Cox proportional hazard models were used to test the association of these SNPs with overall survival (OS) and BC-specific survival (BCS). For the confirmed loci, we performed an accessory analysis of publicly available gene expression data and the prognosis in a different patient group. One of the 11 SNPs, rs3803662 ( TOX3 ) and none of the 62 candidate/GWAS SNPs were associated with OS and/or BCS at P 〈0.01. The genotypic-specific survival for rs3803662 suggested a recessive mode of action [hazard ratio (HR) of rare homozygous carriers=1.21; 95% CI: 1.09–1.35, P =0.0002 and HR=1.29; 95% CI: 1.12–1.47, P =0.0003 for OS and BCS, respectively]. This association was seen similarly in all analyzed tumor subgroups defined by nodal status, tumor size, grade and estrogen receptor. Breast tumor expression of these genes was not associated with prognosis. With the exception of rs3803662 (TOX3), there was no evidence that any of the SNPs associated with BC susceptibility were associated with the BC survival. Survival may be influenced by a distinct set of germline variants from those influencing susceptibility.