Within the moderately eroded Manicouagan structure a sheet of clast‐laden impact melt 230 m thick and 55 km in diameter forms an annular plateau surrounding an uplift of shocked anorthosite. The melt sheet is divided into three vertically gradational units based on decreasing clast abundance and coarsening of the melt above the base. A very fine‐grained lower unit, rich in millimeter‐ and centimeter‐sized inclusions, thickens radially outward but is overlapped and replaced toward the center by a coarser middle unit containing fewer, larger inclusions. The upper unit is medium grained, virtually clast free, and texturally the most homogeneous of the three melt units. Within the lower and middle units a variety of textures are present. Textural development is a function of the cooling rate determined by stratigraphic position and the degree of supercooling determined by initial clast content. The mineralogy of the melt rocks is similar in all units and consists of zoned plagioclase, sanidine, Ca‐poor pyroxene, augite, quartz (rare in the lower unit), magnetite‐ilmenite intergrowths, smectite, and apatite, Pseudomorphs after olivine, and pigeonite in various stages of inversion to hypersthene, are widespread only in the upper unit, while minor biotite and hornblende are confined to the lower and middle units. Replacement of olivine and much of the Ca‐poor pyroxene by smectite, and alteration of iron oxides occurred during late stage crystallization and subsolidus cooling. The melt rocks as a group are chemically homogeneous, with a bulk composition similar to that of latite. No statistically significant regional chemical variations were found as a function of vertical, lateral, or radial position in the melt sheet. A local mafic variant represented by two samples with poikilitic texture indicates that the melt is not completely chemically homogeneous. The poikilitic rocks texturally resemble some Apollo 17 impact melt rocks and are inferred to have had a similar origin and thermal history.

Abstract. The 65‐km‐diameter Manicouagan impact structure has an eroded 230‐m‐thick sheet of clast‐laden, impact melt rock with an estimated preerosional volume of >270 km3. All samples are characterized by mineral and lithic clasts or their incompletely digested remnants. Drawing upon previous theoretical studies of shock waves, we suggest that the Manicouagan melt formed in 1 or 2 s in a 5‐km‐radius hemisphere near the point of impact. The melt accelerated to a few kilometers per second, and the melt and the less shocked debris surrounding it flowed downward and outward for a few minutes until the melt formed a lining of a 5‐ to 8‐km‐deep, 15‐ to 22‐km‐radius cavity. Extremely turbulent flow thoroughly homogenized the melt and promoted the incorporation and progressive digestion of slower moving, less shocked, cooler debris surrounding the melt. This debris had been finely fragmented, but not melted, to grain sizes of less than 1 mm by the passage of the shock waves. Because of the fine grain size, the melt and fragmented debris equilibrated thermally in about 100 s. During thermal equilibration, virtually all clastic debris (i.e. alkali feldspar, biotite, hornblende, garnet, and scapolite), other than highly refractory quartz and plagioclase as well as many of the centimeter size lithic clasts other than anorthosite, were digested. The preservation of quartz and plagioclase mineral clasts implies that the clasts and melt equilibrated to temperatures near but not above the liquidus. Plagioclase nucleation was initiated by the drop in temperature and possibly by direct nucleation on undigested debris. The initiation of crystallization vastly increased the melt viscosity, preventing settling of 10‐mm clasts of basement. Flow of melt through basement fractures is evidence that readjustment of the crater floor took place during the period of clast‐melt thermal equilibration.

Results of crossing triploid females of ornamental koi, a variant of Common Carp Cyprinus carpio, with diploid koi males in two consecutive spawning seasons (2014 and 2015) are presented. A total of seven progenies from six triploid females (one female was spawned twice) were produced and analyzed. The same as normal diploid females, triploid females were highly fertile and produced hundreds of thousands of eggs (up to 400,000 per female). Processes of embryo incubation and hatching of larvae in progenies obtained from triploid females proceeded normally; however, mass mortality of hatched larvae occurred at the swim‐up stage. Nevertheless about 200,000 swim‐up larvae were obtained and stocked for further rearing. A total of about 1,000 juveniles (or 0.5% of the number of stocked larvae) was collected from outdoor tanks. As expected, all analyzed larvae and juveniles in control progenies obtained by crosses of diploid females with diploid males were diploid. About 95% of analyzed fish (larvae and juveniles) obtained by crossing triploid females with diploid males were aneuploids with ploidy ranging from 2.14n to 3.0n; mean values of fish ploidy in progenies obtained from different triploid females varied from 2.47n to 2.63n. Since aneuploid fish have in their genomes one haploid set from parental males, the data obtained indicate that triploid koi females produced aneuploid eggs with ploidy range from haploid to diploid level and a modal ploidy level around 1.5n, similar to the production of aneuploid spermatozoa observed earlier for triploid males in fish. About 5% of juveniles obtained from triploid females had ploidy range from 3.21n to 4.0n. Apparently these fish resulted from spontaneous suppression of the second meiotic division in aneuploid eggs.

The objective of this study was to characterize the genetics of second generation (F ) koi Cyprinus carpio × goldfish Carassius auratus hybrids. Spermatozoa produced by a novel, fertile F male were found to be diploid by flow-cytometric analysis. Backcross (F female × C. carpio male and C. carpio female × F male) juveniles were triploid, confirming that female and male F hybrids both produced diploid gametes. The vast majority of surviving F juveniles was diploid and small proportions were aneuploid (2·1n-2·3n and 3·1n-3·9n), triploid (3n) and tetraploid (4n). Microsatellite genotyping showed that F diploids repeated either the complete maternal or the complete paternal genotype. Fish with the maternal genotype were female and fish with the paternal genotype were male. This demonstrates that F diploids were the result of spontaneous gynogenesis and spontaneous androgenesis. Analysis of microsatellite inheritance and the sex ratio in F crosses showed that spontaneous gynogenesis and androgenesis did not always occur in equal proportions. One cross was found to have an approximate equal number of androgenetic and gynogenetic offspring while in several other crosses spontaneous androgenesis was found to occur more frequently than spontaneous gynogenesis.

We describe fluid inclusions in five stony meteorites: diogenite ALHA 77256 and chondrites Bjurbole (H4), Faith (H5), Holbrook (L4), and Juin (H5). This brings to seven the number of stony meteorites in which fluid inclusions have been confirmed. The fluid inclusions in diogenite ALHA 77256 display a vapor bubble that decreases in volume from −180°C, the lowest temperature attainable in our microthermometric runs, to homogenization of liquid plus vapor to liquid. Homogenization temperatures are reproducible in each inclusion, and range from 25°C to over 225°C; some vapor plus liquid inclusions remain at 225°C, the highest temperature in our microthermetric experiments. On cooling, the fluid in some inclusions apparently freezes, as indicated by deformation and immobilization of the vapor bubble at low temperatures. However, temperatures of melting are difficult to observe and are not reproducible. Preliminary laser Raman spectroscopy shows symmetric and antisymmetric stretch bands characteristic of H2O. Microthermometric data suggest that the fluid in diogenite ALHA 77256 is aqueous with a high solute content. Fluid inclusions discovered in four chondrites have similar properties.