Basalt cores

Basalt cores were cut from rocks supplied by Basalt Waste Isolation Project (BWIP) personnel and ground to size (6.83-cm diameter by 14.60-cm long) on a lathe with distilled water coolant These rocks were Pomona-flow basalt from the Pasco basin in the vicinity of the Near Surface Test Facility, U.S. DOE Hanford site Characterization of this basalt can be found elsewhere (2 ). 

Because these core were not permeable to water even at high pressure, they were mechanically split to provide a path for water flow. To split the core, a sharp, hardened steel edge was pressed along the length of the core, using a hydraulic press, until the cores fractured. Details of the operation and the mounting of basalt cores in the core holder vessel can be found elsewhere (3). 

The fissured basalt cores and bentonite were altered by placing them in an autoclave under simulated groundwater at 320°C for 30 and 60 days to simulate 1000 y and 2000 y aging, respectively The waste-form wafers for both experiments were aged in the same manner by treating them for 17 days in saturated steam at 340°C The details of these procedures and the rationale for their use have been published previously (7). The effects of saturated steam on borosilicate glass were discussed in a recent publication (8) ... 

Changes in Analog Groundwater Composition The data in Figure 2 for the first three analog experiments (which used unaltered waste form, bentonite, and basalt cores) show that the groundwater exiting the basalt fissure reaches a steady-state composition for [Na+] and [Ca +] soon after the start of the experiment ... 

Table VI shows the concentrations of plutonium, neptunium, and uranium measured at the inlet and outlet of the unaltered and hydrothermally-altered basalt core fissures in the first five analog experiments (see Table I) Under conditions simulating a repository that was unaltered by groundwater interaction (Table I, Exp 1-3), both Np and Pu, in the concentrations developed in these analog experiments from the leaching of the waste form, were substantially retarded within the 14.6-cm basalt fissure In fact, as can be seen from Figure 4, almost all of Np activity was sorbed on the first one-third of the rock fissure The data in Figure 4 have an estimated error, based on counting statistics above, of approximately 2 counts per 1000 seconds Uranium retardation was determined to be not as complete ...

Recently, the first fossil fungi have been found in the submarine, deep basaltic earth crust (Schumann et al., 2004). The fossils were detected in thin sections obtained from drilled basaltic cores collected during Ocean Drilling Program, Leg 200, in the North Pacific Ocean (Stephen et al., 2003). Unique filamentous fossilized fungi were observed in the carbonate-filled vesicles of a massive tholeiitic lava flow from the upper oceanic crust at a depth of 51 m below sea floor, beneath sediment and magmatic rocks, and under an overlying water column of about 5000 m (Fig. 16.1). These... 

Figure 4. Behavior of the absorption coefficient of Pu as a function of the concentration of other salts for dense basalt cores...

To test this model of the relationship of the surface absorption coefficient to the migration rate through the fissure, we constructed a model fissure. This was done by sealing a smooth slab cut from a basalt core to the face of a Teflon block that had a 0.0127-cm depression milled dovm its face. This then formed a Assure that was 0.0127 X 1 X 4 cm in size, tracer was dissolved in 10 ml of water and allowed to... 

Crushed basalt core from Well S-4 at 0.3 m below surface at Box Canyon near Idaho National Laboratory (INL). 

Figure 4. Plot of Li isotopic composition vs. MgO content for samples of the Kilauea Iki lava lake, Hawaii (Tomascak et al. 1999b). Cored basalt samples show a range of crystallization temperatures (estimated for four of the samples). The absence of permil-level variation in 5 Li indicates that Li isotopes do not fractionate appreciably during crystallization in mantle systems. Open symbols (o) are replicate measurements.

Edwards R, Sedwick PN, Morgan V, Boutron CF, Hong S (1998) Iron in ice cores from Law Dome, east Antarctica implications for past deposition of aerosol iron. Ann Glaciol 27 365-370 Filer JM (2001) Oxygen isotope variations of basaltic lavas and upper mantle rocks. Rev Mineral Geochem 43 319-364... 

An astonishing recent discovery is that there are bacteria living deep in the Earth s crust. Colonies of anaerobic bacteria have been isolated from boreholes 1,500 m deep in basaltic rock formations. The bacteria use H2 as electron donor, which may originate from fermentation of organic matter, or from a purely inorganic reaction of iron of the Earth s core with water (Stevens and McKinley 1995 Anderson et al. 1998). 

Martian meteorites and Mars rover analyses suggest that it is a basalt-covered world, a conclusion supported by orbital measurements. Basalts of different ages appear to have distinct compositions. Since its original differentiation, the Martian mantle has remained geochemically isolated, although it is periodically melted to produce basalts. The core has an appreciable amount of sulfide, as inferred from trace elements in basalts. Water, once important in producing clays and sulfates, has now retreated into the subsurface. 

The compositions of the crusts of the Moon and Mars are distinct - one is dominated by feldspathic cumulates from an early magma ocean, and the other by basaltic lavas. Regional patterns reflect differences in subjacent mantle compositions. The compositions of the mantles and cores of these bodies can be constrained by chemical analyses of mantle-derived basalts. The interiors of both bodies have remained geochemically isolated, because of the absence of plate tectonics. 

Pomona basalt flow. A third interbed sample was taken from drilling cores of the Mabton Interbed, located between the Saddle Mountains and Wanapum Basalts. The Mabton Interbed is the first continuous, major interbed above the candidate repository horizons in the Grande Ronde Basalts. Mineralogical characteristics of the interbed materials are summarized in Table n. A more complete discussion of the characteristics of the interbed materials may be found in Reference (4). 

These quantities are both higher for experiment 4 and 5 than for the three experiments with unaltered repository components The loss of Pu through the core for experiments 1 and 2, for example, was 0 4 and 0 1 dpm/mL, respectively in experiments 4 and 5 the loss of Pu through the core appears to be 20 to 40 times greater This exercise is intended to show that there is no legitimate way to compare the behavior of altered and unaltered basalt from these data Experiment 6, yet to begin, should clarify this situation. What is clear from comparing the data in Table VI is that actinide behavior in altered and unaltered repository situations will be quite different ... 

The first identification of cosmogenic noble gas in crustal rocks was reported by Kurz (1986). Kurz measured a series of basaltic-drilled core samples from Mauna Loa volcanoes in the Hawaiian Islands. The lava flow (14C age 20,000 a) has retained its surface flow structure and, therefore, was concluded to have experienced little surface erosion. Because the 3He concentration in the surface of the lava flow (10 I2-I0 cm3STPg ) gave reasonable agreement with a theoretical production... 

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