bluuebunny/crossref_metadata_2025_split huggingface dataset:
Climatic control of trace fossil distribution in the marine realm
Authors: Goldring Roland , Cadée Gerhard C. , D’Alessandro Assunta , De Gibert Jordi M. , Jenkins Richard , Pollard John E. 
Published: April 2008

Abstract

Modern coastal and shoreface faunas exhibit strong latitude (climate) controlled distributions. In contrast, most ichnotaxa are long-ranging, and ichnofacies are widely distributed geographically. This is readily explained by the dominantly warmer and more equable climates of much of the past, as well as the diversity of the producers of most ichnotaxa. Nevertheless, in the Pleistocene, and in the Eocene, cool-water ichnofabrics can be recognized. The latitudinal distributions of thalassinidean crustaceans and infaunal spatangoid echinoids are examined because of their propensity to form distinctive and often abundant trace fossils. Three climatic zones are tentatively recognized from modern shore and shoreface sediments, and which are considered to extend back to the Mesozoic:
tropical and subtropical
with pellet-lined burrows (
Ophiomorpha
), echinoid burrows and other traces;
temperate
with echinoid burrows and mud-lined or non-lined thalassinidean burrows (
Thalassinoides
), but without
Ophiomorpha
; and
arctic
(cold waters) with only a molluscan and annelid trace fossil association. Examples demonstrating this climatic trend are drawn from the Cenozoic and Pleistocene.
Differentiation of estuarine and offshore marine deposits using integrated ichnology and sedimentology: Permian Pebbley Beach Formation, Sydney Basin, Australia
Authors: Bann Kerrie L. , Fielding Christopher R. , MacEachern James A. , Tye Stuart C. 
Published: April 2008

Abstract
This study integrates ichnology and sedimentology to refine the palaeoenvironmental and sequence stratigraphic interpretations of the Early Permian Pebbley Beach Formation, in the southern Sydney Basin, Australia. This succession has been interpreted previously to reflect entirely inner to outer shelf and slope environments of deposition. Detailed analysis of the formation reveals ichnological and sedimentological characteristics that contradict a fully marine interpretation. Instead, the interval reflects the vertical superposition and lateral juxtaposition of brackish-water and fully marine units. Marine facies comprise: (1) thoroughly bioturbated muddy siltstone (lower offshore); (2) thoroughly bioturbated sandy siltstone (upper offshore); (3) interbedded bioturbated sandy siltstone and laminated sandstone (delta-influenced offshore transition); (4) thoroughly bioturbated muddy sandstone (distal lower shoreface); (5) interbedded laminated sandstone, bioturbated muddy sandstone and dark claystone (delta-influenced lower shoreface); and (6) bioturbated, laterally variable sandstones (transgressive sand sheets). Estuarine facies comprise: (1) channelized heterolithic sandstone-mudstone (active estuarine channels); (2) sheet-like heterolithic sandstone-mudstone (active estuarine basins); and (3) laminated mudstone (abandoned estuarine channels and basins). The interpreted fully marine deposits contain ichnological suites that exhibit moderate to intense bioturbation, high diversities (31 ichnospecies belonging to 20 ichnogenera), uniform distributions of ichnogenera, and significant numbers of structures reflecting specialized feeding/grazing behaviours. In marked contrast, interpreted estuarine (brackish-water) deposits contain impoverished ichnological suites (9 ichnogenera), show variable but significantly reduced degrees of bioturbation intensity, pronounced variability in ichnogenera distributions and the predominance of a few, simple forms representing simple feeding strategies of resilient trophic generalists. The new analysis allows the recognition of a series of highly top-truncated and condensed sequences (cycles of relative sea-level fall and physical rise), which can be physically correlated over several kilometres. Sequence boundaries typically cut down through shoreface sandstones to directly overlie offshore facies, leading to an interface with little apparent lithological contrast. In the absence of laterally continuous exposure, these surfaces may be recognized by careful ichnofacies evaluation. Thus the re-evaluation presented herein has facilitated a more realistic sequence stratigraphic analysis of the Pebbley Beach Formation.
Pin-pricking the elephant: evidence on the origin of the Ontong Java Plateau from Pb-Sr-Hf-Nd isotopic characteristics of ODP Leg 192 basalts
Authors: Tejada M. L. G. , Mahoney J. J. , Castillo P. R. , Ingle S. P. , Sheth H. C. , Weis D. 
Published: April 2008

Abstract

Age-corrected Pb, Sr and Nd isotope ratios for early Aptian basalt from four widely separated sites on the Ontong Java Plateau that were sampled during Ocean Drilling Program Leg 192 cluster within the small range reported for three earlier drill sites, for outcrops in the Solomon Islands, and for the Nauru and East Mariana basins. Hf isotope ratios also display only a small spread of values. A vitric tuff with ε
Nd
(
t
) = +4.5 that lies immediately above basement at Site 1183 represents the only probable example from Leg 192 of the Singgalo magma type, flows of which comprise the upper 46–750 m of sections in the Solomon Islands and at Leg 130 Site 807 on the northern flank of the plateau. All of the Leg 192 lavas, including the high-MgO (8–10 wt%) Kroenke-type basalts found at Sites 1185 and 1187, have ε
Nd
(
t
) between +5.8 and +6.5. They are isotopically indistinguishable from the abundant Kwaimbaita basalt type in the Solomon Islands, and at previous plateau, Nauru Basin and East Mariana Basin drill sites. The little-fractionated Kroenke-type flows thus indicate that the uniform isotopic signature of the more evolved Kwaimbaita-type basalt (with 5–8 wt% MgO) is not simply a result of homogenization of isotopically variable magmas in extensive magma chambers, but instead must reflect the signature of an inherently rather homogeneous (relative to the scale of melting) mantle source. In the context of a plume-head model, the Kwaimbaita-type magmas previously have been inferred to represent mantle derived largely from the plume source region. Our isotopic modelling suggests that such mantle could correspond to originally primitive mantle that experienced a rather minor fractionation event (e.g. a small amount of partial melting) approximately 3 Ga or earlier, and subsequently evolved in nearly closed-system fashion until being tapped by plateau magmatism in the early Aptian. These results are consistent with current models of a compositionally distinct lower mantle and a plume-head origin for the plateau. However, several other key aspects of the plateau are not easily explained by the plume-head model. The plateau also poses significant challenges for asteroid impact, Icelandic-type and plate separation (perisphere) models. At present, no simple model appears to account satisfactorily for all of the observed first-order features of the Ontong Java Plateau.
Volatiles in submarine basaltic glasses from the Ontong Java Plateau (ODP Leg 192): implications for magmatic processes and source region compositions
Authors: Roberge Julie , White Rosalind V. , Wallace Paul J. 
Published: April 2008

Abstract

Submarine basaltic glasses from five widely separated sites on the Ontong Java Plateau (OJP) were analysed for major and volatile elements (H
2
O, CO
2
, S, Cl). At four of the sites (1183, 1185, 1186, 1187) the glass is from pillow basalt rims, whereas at Site 1184 the glass occurs as non-vesicular glass shards in volcaniclastic rocks. Glassy pillow rims from Site 1187 and the upper group of flows at Site 1185 have 8.3–9.3 wt% MgO compared with values of 7.2–8.0 wt% MgO for glasses from Sites 1183, 1184 1186, and the lower group of flows at Site 1185. Low-MgO glasses have slightly higher H
2
O contents (average 0.22 wt% H
2
O) than high-MgO glasses (average 0.19 wt%), with the exception of Site 1184, where low-MgO glasses have lower H
2
O (average 0.16 wt%). Average S concentrations are 910 ± 60 ppm for the high-MgO glasses v. 1030 ± 60 ppm for the low-MgO glasses. When compared with mid-ocean ridge basalt (MORB), the OJP glasses have lower S at comparable FeO
T
. This suggests that OJP basaltic magmas were not saturated with immiscible sulphide liquid during crystallization, but small decreases in S/K
2
O and S/TiO
2
with decreasing MgO require some sulphide fractionation. Measurements of the wavelength of the S
K
α peak in the glasses indicate low oxygen fugacities comparable to MORB values. Chlorine contents of the glasses are very high compared with MORB, and Cl/K ratios for all glasses are relatively high (>0.7). This ratio is sensitive to assimilation of hydrothermally altered material, so the high values indicate assimilation during shallow-level crystallization of OJP magmas. Ratios of H
2
O to Ce, which have similar incompatibility to each other, are higher than most depleted and enriched MORB. However, these high H
2
O/Ce values are probably also caused by the same assimilation process that results in high Cl. The water content of the high MgO-magmas before contamination is estimated to be approximately 0.07 wt% H
2
O, corresponding to H
2
O/Ce of 135 for OJP basalts, a value at the low end of the range for Pacific MORB. There is no evidence for high H
2
O contents that would have significantly increased extents of mantle melting beneath the OJP, and the estimated H
2
O content of the OJP mantle source region (170 ± 30 ppm H
2
O) is similar to that of the depleted MORB source (140 ± 40 ppm H
2
O). Instead, large extents of melting beneath the OJP must have been caused by a relatively high mantle potential temperature, consistent with upwelling of a hot mantle plume.
Particle size analysis by laser diffraction
Authors: Blott Simon J. , Croft Debra J. , Pye Kenneth , Saye Samantha E. , Wilson Helen E. 
Published: April 2008

Abstract
Particle size distribution is a fundamental property of any sediment or soil, and particle size determination can provide important clues to sediment provenance. For forensic work, the particle size distribution of sometimes very small samples requires precise determination using a rapid and reliable method with a high resolution. A protocol has been developed using a Coulter™ LS230 laser granulometer, which can analyse particles in the size range 0.04 μm–2000μm. The technique is essentially non-destructive, permitting the recovery of critical samples, and has been demonstrated to have high precision for a range of soils, sediments and powders of interest in forensic investigations.
The long-term fate of CO
2
in the subsurface: natural analogues for CO
2
storage
Authors: Baines Shelagh J. , Worden Richard H. 
Published: April 2008

Abstract

CO
2
is a common gas in geological systems so that planned storage of CO
2
in the subsurface may do no more than mimic nature. Natural CO
2
has a wide number of sources that can be at least partly identified by carbon stable isotope geochemistry. Three pairs of case studies with different reservoir characteristics and CO
2
contents have been examined to assess the natural impact of adding CO
2
to geological systems. Carbonate minerals partially dissolve when CO
2
is added simply because the CO
2
dissolves in water and forms an acidic solution. Therefore, carbonate minerals in the subsurface are not capable of sequestering secondary CO
2
. The addition of CO
2
to a pure quartz sandstone (or a sandstone in which the supply of reactive aluminosilicate minerals has been exhausted by excess natural CO
2
addition) will have no consequences: the CO
2
will simply saturate the water and then build up as a separate gas phase. The addition of CO
2
to carbonate cemented sandstone without reactive aluminosilicate minerals will induce a degree of carbonate mineral dissolution but no solid phase sequestration of the added CO
2
. When CO
2
is naturally added to sandstones it will induce combined aluminosilicate dissolution and carbonate cementation if the aluminosilicate minerals contain calcium or magnesium (or possibly iron). Examination of a CO
2
-filled porous sandstone with abundant reactive aluminosilicate minerals that received a huge CO
2
charge about 8000 to 100 000 years ago reveals minimal evidence of solid phase sequestration of the added CO
2
. This indicates that either dissolution of reactive aluminosilicates or precipitation of carbonate minerals is relatively slow. It is very likely that the slow dissolution of reactive aluminosilicates is the rate-limiting step.

Solid phase sequestration of CO
2
occurs only when reactive aluminosilicates are present in a rock and when the system has had many tens to hundreds of thousands of years to equilibrate. The two critical aspects of the behaviour of CO
2
when injected into the subsurface are (1) that the rock must contain reactive Ca and Mg aluminosilicates and (2) that reaction to produce carbonate minerals is extremely slow on a human timescale. The reactive minerals include anorthite, zeolite, smectite and other Fe- and Mg-clay minerals. Such minerals are absent from clean sandstones and limestones but are present in ‘dirty’ standstones (lithic arenites which are mineralogically immature) and some mudstones.

The analysis of geological analogues shows that injection of CO
2
into carbonate-bearing rocks that do not contain reactive minerals will induce dissolution of the carbonate, whether it is a matrix cement, rock fragment, fault seal or part of a top-sealing mudstone.
Heat pumps as a tool for energy recovery from mining wastes
Authors: Banks David , Skarphagen H. , Wiltshire R. , Jessop C. 
Published: April 2008

Abstract
Heat pumps extract heat energy from a low-temperature source and transfer it to a higher temperature sink, usually via a closed loop of volatile ‘refrigerant’ fluid in a compression/expansion cycle. They can be efficiently used for space heating (and cooling), extracting heat from seawater, rivers, lakes, groundwater, rocks, sewage, or mine water. Electrical energy powers the heat pump’s compressor. The ratio of total heat output to electrical energy input, called the coefficient of performance, typically ranges from 3.0 to 6.0. The use of mine water for space heating or cooling purposes has been demonstrated to be feasible and economic in applications in Scotland, Canada, Norway, and the USA. Mine water is an attractive energy resource due to: (1) the high water storage and water flux in mine workings, representing a huge renewable enthalpy reservoir; (2) the possibility of re-branding a potentially polluting environmental liability as a ‘green’ energy resource; and (3) the development of many mine sites as commercial/industrial parks with large space heating/cooling requirements. The exothermic nature of the pyrite oxidation reaction (> 1000 kJ/mol) implies added benefits if closed-loop systems can harness the chemical energy released in mine-waste tips. An appreciation of geochemistry also assists in identifying and solving possible problems with precipitation reactions occurring in heat pump systems.
Digital field data acquisition: towards increased quantification of uncertainty during geological mapping
Authors: Jones Richard R. , McCaffrey Kenneth J. W. , Wilson Robert W. , Holdsworth Robert E. 
Published: April 2008

Abstract
Traditional methods of geological mapping were developed within the inherent constraints imposed by paper-based publishing. These methods are still dominant in the earth sciences, despite recent advances in digital technology in a range of fields, including globalpositioning systems, geographical information systems (GIS), 3-D computer visualization, portable computer devices, knowledge engineering and artificial intelligence. Digital geological mapping has the potential to overcome some serious limitations of paper-based maps. Although geological maps are usually highly interpretive, traditional maps show little of the raw field data collected or the reasoning used during interpretation. In geological mapping, interpretation typically relies on the prior experience and prior knowledge of the mapper, but this input is rarely published explicitly with the final printed map. Digital mapping techniques open up new possibilities for publishing maps digitally in a GIS format, together with spatially referenced raw field data, field photographs, explanation of the interpretation process and background information relevant to the map area. Having field data in a digital form allows the use of interpolation methods based on fuzzy logic to quantify some types of uncertainty associated with subsurface interpretation, and the use of this uncertainty to evaluate the validity of competing interpretations.
Flow of partially molten crust and origin of detachments during collapse of the Cordilleran Orogen
Authors: Teyssier C. , Ferré E. C. , Whitney D. L. , Norlander B. , Vanderhaeghe O. , Parkinson D. 
Published: April 2008

AbstractIn metamorphic core complexes two types of detachments develop, coupled by flow of partially molten crust: a channel detachment and a rolling-hinge detachment. The channel detachment, on the hinterland side of the orogen, represents the long-lived interface that separates the partially molten crust flowing in a channel from the rigid upper crustal lid. On the foreland side of the core complex, a rolling-hinge detachment develops. This detachment dips toward the foreland, probably affects the whole crust, and its geometry is governed by strain localization at the critical interface between cold foreland and hot hinterland. Activation of the rolling-hinge detachment drives rapid decompression and melting, leading to the diapiric rise of migmatite domes in the footwall of the detachment. A kinematic hinge (switch in sense of shear) separates the two types of detachments. Structural, metamorphic and geo/thermochronological studies in the Shuswap core complex (North American Cordillera), combined with an anisotropy of magnetic susceptibility study of leucogranites concentrated in the detachments, suggest that this orogen collapsed rapidly through the development of channel and rolling-hinge detachments in the early Eocene. The kinematic hinge is currently located approximately 40 km west of the footwall in which it originated, corresponding to a mean exhumation rate of >5 km Ma−1, which explains the near-isothermal decompression recorded within the migmatite dome.
Nd and Sr isotopic signatures of metasedimentary rocks around the South Pacific margin and implications for their provenance
Authors: Adams C. J. , Pankhurst R. J. , Maas R. , Millar I. L. 
Published: April 2008

AbstractAn Nd-Sr isotope database, includingc.200 new analyses, is presented for Palaeozoic and Mesozoic metasedimentary successions extending through southeastern Australia, New Zealand, West Antarctica and the Antarctic Peninsula to southern South America. Combining with U-Pb detrital zircon age data, this enables characterization of New Zealand terranes, especially within the Eastern Province, where there is a progression from westernmost terranes of both volcanic/volcaniclastic and accretionary origin with primitive sediment sources, to easternmost terranes with mature continental sediment inputs. In southern South America, West Antarctica and the Antarctica Peninsula, similar accretionary complexes have Nd model ages principally reflecting mixing of sedimentary material from multiple sources, both mature and juvenile. A mature Gondwana continental provenance dominates in sedimentary basins inboard of the active margin, especially in the Palaeozoic (Western Province, New Zealand, interior West Antarctica and NW Argentina), and contributes significantly to pre-Mesozoic sedimentary rocks of Patagonia east of the Andes. Along the Gondwanaland margin, Nd systematics for younger (late Palaeozoic to early Mesozoic) accretionary complex metasediments reflect younger source inputs, notably in the Scotia metamorphic complex. Many of the accretionary complex deposits must involve significant crustal reworking. There is no apparent South American equivalent of the primitive provenance of the westernmost accretionary terranes of New Zealand.
Episodicity of Mesozoic terrane accretion along the Pacific margin of Gondwana: implications for superplume-plate interactions
Authors: Vaughan A. P. M. , Livermore R. A. 
Published: April 2008

Abstract
A review of evidence for deformation and terrane accretion on the Late Triassic-Early Jurassic margins of Pangaea and the mid-Cretaceous margins of the palaeo-Pacific ocean shows that deformation was global and synchronous with probable superplume events. Late Triassic-Early Jurassic deformation appears to be concentrated in the period 202–197 Ma and was coeval with eruption of the Central Atlantic Magmatic Province, onset of Pangaea break-up, a period of extended normal magnetic polarity and a major mass extinction event, all possible expressions of a superplume event. Mid-Cretaceous deformation occurred in two brief periods, the first from approximately 116 Ma to 110 Ma in the west palaeo-Pacific and the second from roughly 105 Ma to 99 Ma in the east palaeo-Pacific, with both events possibly represented in northeast Siberia. This deformation was coeval with eruption of major oceanic plateaux, core-complex formation and rifting of New Zealand from Gondwana, the Cretaceous normal polarity epoch, and a major radiation of flowering plants and several animal groups, all linked with the mid-Cretaceous superplume event. A simple unifying mechanism is presented suggesting that large continental or oceanic plates, when impacted by a superplume, tend to break-up/reorganize, associated with gravitational spreading away from a broad, thermally generated topographic high and with a resulting short-lived pulse of plate-marginal deformation and terrane accretion.
The early Palaeozoic Orogen in the Central Andes: a non-collisional orogen comparable to the Cenozoic high plateau?
Authors: Lucassen Friedrich , Franz Gerhard 
Published: April 2008

Abstract
The subduction orogeny of the Central Andes, which created the Cenozoic Altiplano-Puna high plateau, shares many geological features with the early Palaeozoic Orogen at the western margin of South America. The presently available datasets for both orogens are compared. The similarities are a large-scale high temperature metamorphism, which was active in the Palaeozoic Orogen over a geological long period of time in the order of 100 Ma and which is active now in the crust of the Cenozoic plateau. It produced abundant granitoid melts from the crust during the Palaeozoic as well as during the Andean Orogen. The main contribution to granitoid magmatism is recycling of felsic crustal material with only minor additions from the mantle. Transport of deep parts of the crust into the erosion level did not occur in both orogens and, in both orogens, large-scale nappe tectonics typical for collision orogens are absent. Based on the similarities of the two orogens it is argued that the early Palaeozoic Orogen is a non-collisional orogen. Indications for terrane accretion are absent in the development of the high-grade metamorphic and igneous basement. The early Palaeozoic Orogen is an analogue for the presently active continental margin and, thus, allows the extrapolation of features which cannot be observed in the Andean Orogen.