Luenhan pikriitit keskisestä Mosambikista - Viestintuojia Karoon laakiobasalttien vaippapluumilähteestä?

We present geochemical and isotopic (Nd, Sr) data for a picrite lava suite from the Luenha River and adjacent areas in Mozambique. The Luenha picrites represent a previously unknown type of picrites related to the Karoo large igneous province (LIP) and are distinguished by their notably low TiO2 contents (0.3-1.0 wt%) and coupling of high Nb/Y with low Zr/Y and Sm/Yb. Relatively high CaO and low Zn/Fe point to a peridotitic mantle source. Contamination-sensitive incompatible element ratios show that one lava flow is likely to be uncontaminated by the crust and its composition suggests a mantle source with primitive mantle-like incompatible element ratios and mildly depleted isotopic ratios (initial Sr-87/Sr-86 = 0.7041 and epsilon(Nd) = +1.4 at 180 Ma). The primary melts of the Luenha picrites had MgO contents in the range of 13-21 wt%. Our preferred estimate for a primary melt composition (MgO = 18 wt%) resembles experimental melts of fertile mantle peridotite at 3-4 GPa and indicates liquidus temperature of 1445-1582 degrees C. Geochemical similarities suggest the Luenha picrites were generated from the same overall primitive mantle-like reservoir that produced the main volume of Karoo flood basalts in the Karoo, Kalahari, and Zambezi basins, whereas the previously identified enriched and depleted (upper) mantle sources of Karoo picrite suites (Mwenezi, Antarctica) were subordinate sources for flood basalts. We propose that the Luenha picrites record melting of a hot, chemically primitive mantle plume source that may have been rooted in the sub-African large low shear velocity province boundary and that such a source might have been the most significant magma source in the Karoo LIP. (C) 2019 The Author(s). Published by Elsevier B.V.Peer reviewe

Raskaat harvinaiset maa-alkuaineet ja laakiobasalttien lähteet

Editor's ChoiceHeavy rare earth elements (HREEs) in mafic and ultramafic volcanic rocks are useful recorders of mantle source processes because their ratios are not easily modified by differentiation. Here we utilize REEBOX PRO, a simulator of adiabatic decompression melting of the mantle, to study the behavior of HREEs in the formation of continental flood basalt (CFB) parental magmas in the mantle. We simulate partial melting of depleted peridotite, pyrolitic peridotite, pyroxenite, and peridotite-pyroxenite mixtures at mantle potential temperatures of 1350-1650 degrees C and lithospheric thicknesses of 50-150 km, and compare the results to natural data. Many large igneous provinces are typified by low-Ti and high-Ti CFBs with contrasting HREE patterns. Our results show that low-Ti CFBs originate mainly from peridotitic sources. Flat mid-ocean ridge basalt-like HREE patterns typical of low-Ti CFBs can be generated beneath thick lithosphere (similar to 100 km), given that mantle potential temperatures are high (>1500 degrees C) and garnet is completely consumed from the source. We thus challenge the common interpretation that flat HREE patterns always indicate shallow sources for CFB parental magmas. High-Ti CFBs require pyroxenite-bearing sources (>= 10%). Contrary to a common view, their steep oceanic island basalt-like HREE patterns can be generated beneath quite a thin lithosphere (similar to 50 km), which is due to increased garnet stability in pyroxenite sources. When applied to CFBs of the Karoo large igneous province, the results are compatible with a model where a mantle plume penetrates a progressively thinning Gondwana lithosphere.Peer reviewe

The nature of the Karoo mantle source region from the perspective of olivine in the Luenha picrites: an oxygen isotopic and chemical study

The Karoo large igneous province has been divided into rift zone and basin-related groups, with picrites from the Luenha river, Mozambique, representing an end-member of the latter. New O isotope, major and trace element data for olivine have been combined with MELTS crystallisation modelling to deconvolve compositional diversity associated with magma differentiation from source-derived heterogeneity. Three olivines populations have been discerned as follows: (1) the 'main trend', which records crystallisation from a variety of magma compositions; (2) the 'low Cu trend', which is inferred to represent xenocrysts or antecrysts; and (3) the 'high CaO' olivines, which record polybaric crystallisation of a primitive, little fractionated magma. The trace element variability in olivine phenocrysts relates partially to sampling of different parts of the same overall magma transport and storage systems, and partly to heterogeneity of parental magmas and their mantle sources. When the measured delta O-18(olivine) values have been converted into delta O-18(melt) values, the mean delta O-18(melt) values for the 'main trend' and 'low Cu' groups are indistinguishable from each other (5.7 +/- 0.1 parts per thousand, 2 sigma); however, the mean delta O-18(melt) value of 6.1 +/- 0.1 parts per thousand for the 'high CaO' group is distinctly enriched. These data record source heterogeneity and suggest contributions from two mantle sources, one with elevated delta O-18, and another with more 'typical' mantle delta O-18. Combining these data with previously reported trace element and Nd and Sr isotope data support derivation from a mantle source similar to non-chondritic bulk silicate earth, but with minor contributions (1-2% for the enriched magmas) from a recycled sedimentary component. This points to the importance of a primitive mantle source for the basin-related successions in Karoo.Peer reviewe

Genetic architecture of human plasma lipidome and its link to cardiovascular disease

Abstract Understanding genetic architecture of plasma lipidome could provide better insights into lipid metabolism and its link to cardiovascular diseases (CVDs). Here, we perform genome-wide association analyses of 141 lipid species (n = 2,181 individuals), followed by phenome-wide scans with 25 CVD related phenotypes (n = 511,700 individuals). We identify 35 lipid-species-associated loci (P <5 ×10−8), 10 of which associate with CVD risk including five new loci-COL5A1, GLTPD2, SPTLC3, MBOAT7 and GALNT16 (false discovery rate<0.05). We identify loci for lipid species that are shown to predict CVD e.g., SPTLC3 for CER(d18:1/24:1). We show that lipoprotein lipase (LPL) may more efficiently hydrolyze medium length triacylglycerides (TAGs) than others. Polyunsaturated lipids have highest heritability and genetic correlations, suggesting considerable genetic regulation at fatty acids levels. We find low genetic correlations between traditional lipids and lipid species. Our results show that lipidomic profiles capture information beyond traditional lipids and identify genetic variants modifying lipid levels and risk of CVD

Chromosome Xq23 is associated with lower atherogenic lipid concentrations and favorable cardiometabolic indices

Abstract Autosomal genetic analyses of blood lipids have yielded key insights for coronary heart disease (CHD). However, X chromosome genetic variation is understudied for blood lipids in large sample sizes. We now analyze genetic and blood lipid data in a high-coverage whole X chromosome sequencing study of 65,322 multi-ancestry participants and perform replication among 456,893 European participants. Common alleles on chromosome Xq23 are strongly associated with reduced total cholesterol, LDL cholesterol, and triglycerides (min P = 8.5 × 10−72), with similar effects for males and females. Chromosome Xq23 lipid-lowering alleles are associated with reduced odds for CHD among 42,545 cases and 591,247 controls (P = 1.7 × 10−4), and reduced odds for diabetes mellitus type 2 among 54,095 cases and 573,885 controls (P = 1.4 × 10−5). Although we observe an association with increased BMI, waist-to-hip ratio adjusted for BMI is reduced, bioimpedance analyses indicate increased gluteofemoral fat, and abdominal MRI analyses indicate reduced visceral adiposity. Co-localization analyses strongly correlate increased CHRDL1 gene expression, particularly in adipose tissue, with reduced concentrations of blood lipids

Evidence of a causal effect of genetic tendency to gain muscle mass on uterine leiomyomata

Uterine leiomyomata (UL) are the most common tumours of the female genital tract and the primary cause of surgical removal of the uterus. Genetic factors contribute to UL susceptibility. To add understanding to the heritable genetic risk factors, we conduct a genome-wide association study (GWAS) of UL in up to 426,558 European women from FinnGen and a previous UL meta-GWAS. In addition to the 50 known UL loci, we identify 22 loci that have not been associated with UL in prior studies. UL-associated loci harbour genes enriched for development, growth, and cellular senescence. Of particular interest are the smooth muscle cell differentiation and proliferation-regulating genes functioning on the myocardin-cyclin dependent kinase inhibitor 1A pathway. Our results further suggest that genetic predisposition to increased fat-free mass may be causally related to higher UL risk, underscoring the involvement of altered muscle tissue biology in UL pathophysiology. Overall, our findings add to the understanding of the genetic pathways underlying UL, which may aid in developing novel therapeutics.Peer reviewe

New insights into the genetic etiology of Alzheimer’s disease and related dementias

Characterization of the genetic landscape of Alzheimer’s disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/‘proxy’ AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele

New insights into the genetic etiology of Alzheimer’s disease and related dementias

Characterization of the genetic landscape of Alzheimer’s disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/‘proxy’ AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele