Holocene millennial/centennial‐scale multiproxy cyclicity in temperate eastern Australian estuary sediments

We have undertaken a comparative study of down‐core variation in multiproxy palaeoclimate data (magnetic susceptibility, calcium carbonate content and total organic carbon) from two coastal water bodies (Myall and Tuggerah Lakes) in temperate eastern Australia to identify local, regional and global‐forcing factors within Holocene estuarine sediments. The two lakes lie within the same temperate climate zone adjacent to the Tasman Sea, but are not part of the same catchment and drain different geological provinces. One is essentially a freshwater coastal lake whereas the other is a brackish back‐barrier lagoon. Despite these differences, data from two sites in each of the two lakes have allowed us to investigate and compare cyclicity in otherwise uniform, single facies sediments within the frequency range of 200–2000 years, limited by the sedimentation rate within the lakes and our sample requirements. We have auto‐ and cross‐correlated strong periodicities at ～360 years, ～500–530 years, ～270–290 years, 420–450 years and ～210 years, and subordinate periods of ～650 years, 1200–1400 years and ～1800 years. Our thesis is that climate is the only regionally available mechanism available to control common millennial and centennial scale cyclicity in these sediments, given the geographical and other differences. However, regional climate may not be the dominant effect at any single time and either location. Within the range of frequency spectral peaks we have identified, several fall within known long‐term periodical fluctuations of sun spot activity; however, feedback loops associated with short‐term orbital variation, such as Dansgaard–Oeschger cycles, and the relationship between these and palaeo‐ENSO variation, are also possible contributors. Copyright © 2005 John Wiley & Sons, Ltd.     

The observed intermediate-degreef-mode eigenfrequency spectrum of the sun and tests of the mode classification proficiency

Power spectra of the 1979 solar differential observations (Bos, 1982) have been analyzed for evidence of intermediate-degreef-modes. A set of 19 intermediate-degreef-mode multiplets has been identified and classified based on more than 300 classified modes of oscillation. The angular degree of the multiplets ranges from 18 to 36. Them=0 eigenfrequency spectrum, measured with an accuracy of typically 0.01–0.02 Hz, was found to be on the average 10 Hz greater than that predicted by the standard solar model of Saio (1982). Rotational splitting effects up to fifth order inm were obtained. The multiplet fine structure that is linear inm was found to be consistent with the internal rotation curve obtained by Hillet al. (1986a). The multiplet fine structure that is described by terms that are cubic and fifth order inm were found to be consistent with the differential rotation curve of Hillet al. (1986b). The probability that this set of 19 Zeeman-like frequency patterns were obtained from a set of peaks randomly distributed in frequency was estimated to be 10^–9. The effectiveness of the mode detection and classification program in this work has been established in part by observing the horizontal spatial properties of thef-mode eigenfunctions. One consequence obtained from the study of the horizontal spatial properties of the modes is the estimate, obtained observationally, of the number of correct mode identifications: these results indicate that 73±6% of the 374 modes are correctly classified.SCLERA is an acronym for Santa Catalina Laboratory for Experimental Relativity by Astrometry, a facility operated by the University of Arizona.     

Spinifex biogeochemical expressions of buried gold mineralisation: The great mineral exploration penetrator of transported regolith

A major challenge for mineral explorers is to efficiently detect mineralisation beneath the weathered cover that extends across the landscape. Determination of the elemental composition of plants (biogeochemical exploration) can aid in the detection of buried ore deposits due to their root penetration through the weathered cover. At the coyote prospect in Western Australia a range of plant species were sampled traversing a buried Au orebody. Here it is shown that the soft spinifex (Triodia pungens) accumulated important pathfinder elements related to the mineralisation, which produced a multi-element surficial expression of the underlying ore deposit. Spinifex grasses are one of the most widespread grasses over the Australian continent and have vertical root systems that can extend for many 10s of metres through sedimentary cover and interact with buried mineral deposits and alteration zones in the underlying substrate. Spinifex biogeochemistry therefore has potential to be a low cost, low environmental impact, sampling medium for mineral exploration programs across large parts of arid Australia. The examination of similar grasses from other semi-arid and arid regions from around the world therefore also warrants further investigation.     

Flocculation and sedimentation in the ACE Basin, South Carolina

Extremely rapid deposition of fine-grained sediment has been observed near an artificially created channel between the Edisto and Ashepoo Rivers in South Carolina. Accumulation rates on the order of 0.05 m mo⁻¹ formed a region of fluid mud known as the Mud Reach that was present during a study carried out in May 1998. Subsequent surveys in March and May 1999 found no evidence of fluid mud in this area. Image analysis of photographs of the suspended sediment from 1998 showed that the water column was populated by flocs with a median diameter on the order of 0.3 mm which tended to remain in suspension over the tidal cycle, and flocs on the order of 0.8 mm which remained in the near bottom region except at maximum current speeds. In 1999, both the size and concentration of flocs at the surface remained the same, but the size and abundance of flocs near the bottom was reduced. Disaggregated inorganic grain size analysis of the suspension and samples from a core collected in the Mud Reach indicated that in 1998 the accumulation of material on the bottom was the result of floc settling and that in spite of highu _s values, little sorting of this material was occurring. Grain size analysis of samples deeper in the core showed that the rapidly floc-deposited mud was underlain by coarser, well-sorted sediment, confirming that the Mud Reach was a transient feature. The observed flocculation processes may play a significant role in the trapping of fine-grained sediment throughout this region.     

Measuring surface-layer fluxes of heat and momentum using optical scintillation

An experiment is described showing that an optical scintillation instrument gives reliable values of heat and momentum fluxes in the surface layer, subject to the usual restrictions of homogeneity and steady state. This instrument measures the turbulence inner scale and refractive-index structure parameter, which are used to obtain the fluxes from Monin-Obukhov similarity relationships. The instrument gives space-averaged values over a propagation path that can range in length from tens to hundreds of meters. The history of the use of optical propagation to estimate fluxes is reviewed.     

Analysis and interpretation of patterns within and between hydroclimatological time series in an alpine glacier basin

This paper explores patterns within and between climatological and hydrological time series from an alpine glacier basin. Time series recorded in the basin of the Haut Glacier d'Arolla over the 1989 ablation season are subdivided into five subperiods. Box-Jenkins ARIMA (AutoRegressive Integrated Moving Average) and TFN (Transfer Function-Noise) models are estimated for each of the five subperiods and differences between the models are interpreted in the context of changing glacier hydrology, particularly the changing nature and extent of the glacier drainage network.     

Sulfur redox reactions: Hydrocarbons,native sulfur,Mississippi Valley-type deposits,and sulfuric acid karst in the Delaware Basin,New Mexico and Texas

Hydrocarbons, native sulfur, Mississippi Valley-type (MVT) deposits, and sulfuric acid karst in the Delaware Basin, southeastern New Mexico, and west Texas, USA, are all genetically related through a series of sulfur redox reactions. The relationship began with hydrocarbons in the basin that reacted with sulfate ions from evaporite rock to produce isotopically light ( ³⁴S = -22 to -12) H₂S and bioepigenetic limestone (castiles). This light H₂S was then oxidized at the redox interface to produce economic native sulfur deposits ( ³⁴S = -15 to +9) in the castiles, paleokarst, and along graben-boundary faults. This isotopically light H₂S also migrated from the basin into its margins to accumulate in structural (anticlinal) and stratigraphic (Yates siltstone) traps, where it formed MVT deposits within the zone of reduction ( ³⁴S = -15 to +7). Later in time, in th zone of oxidation, this H₂S reacted with oxygenated water to produce sulfuric acid, which dissolved the caves (e.g., Carlsbad Cavern and Lechuguilla Cave, Guadalupe Mountains). Massive gypsum blocks on the floors of the caves ( ³⁴S = -25 to +4) were formed as a result of this reaction. The H₂S also produced istopically light cave sulfur ( ³⁴S = -24 to -15), which is now slowly oxidizing to gypsum in the presence of vadose drip water.     

The pattern and structure of one-person households in England and Wales and France

"This paper examines the increase of one-person households during the 1980s in England and Wales and France set within the broader context of household change in Europe as a whole....One-person households vary geographically by age, with younger one-person households found especially in larger urban areas; older one-person households have a more varied distribution, although rural and traditional retirement areas have particular concentrations. Increases in numbers are a result of both compositional changes in the population (increasing numbers of divorced and never-marrieds as well as increasing numbers of elderly) and also an increasing propensity to live alone, especially among younger age groups."