Evidence of beneficial role of inclined piles: observations and summary of numerical analyses

The behaviour under seismic loading of inclined piles embedded in two idealized soil profiles, a homogeneous and a non-homogenous “Gibson” soil, is analysed with 3D finite elements. Two structures, modeled as single-degree-of-freedom oscillators, are studied: (1) a tall slender superstructure (H _st = 12 m) whose crucial loading is the overturning moment, and (2) a short structure (H _st = 1 m) whose crucial loading is the shear force. Three simple two-pile group are studied: (a) one comprising a vertical pile and a pile inclined at 25°, (b) one consisting of two piles symmetrically inclined at 25°, and (c) a group of two vertical piles. The influence of key parameters is analysed and non-dimensional diagrams are presented to illustrate the role of raked piles on pile and structure response. It is shown that this role can be beneficial or detrimental depending on a number of factors, including the slenderness of the superstructure and the type of pile-to-cap connection.     

Preliminary stratigraphic and structural architecture of Bhutan: Implications for the along strike architecture of the Himalayan system

High-precision in-situ ion microprobe (SIMS) oxygen isotope analysis of zircons from two diorite intrusions associated with the late Caledonian Lochnagar pluton in Scotland has revealed large differences in the degree of heterogeneity in zircon δ¹⁸O between the diorites. Zircon crystals from the Cul nan Gad diorite (CnG) show a unimodal distribution of oxygen isotope values (δ¹⁸O = 6.0 ± 0.6‰ (2σ)) and no or only minor grain-scale variation. Those from the Allt Darrarie diorite (AD1) show a large range in δ¹⁸O and an apparent bimodal distribution with modes of 6.6 ± 0.4‰ and 7.3 ± 0.4‰. Variations of up to 1.2‰ occur between and within grains; both an increase and decrease in δ¹⁸O with zircon growth has been observed. The δ¹⁸O composition of growing zircon can only change if open-system processes affect the magma composition, i.e. if material of contrasting δ¹⁸O composition is added to the magma. The variability in AD1 is interpreted to represent a cryptic record of magma mixing. A ‘deep crustal hot zone’ is a likely site for generation of the dioritic magmas which developed by mixing of residual melts and crustal partial melts or by melting of mafic lower crustal rocks. The overall small number of zircons with mantle-like δ¹⁸O values (5.3 ± 0.6‰ (2σ)) in the Lochnagar diorites is largely the product of crustal differentiation rather than crustal growth.

The δ¹⁸O of quartz from the CnG and AD1 diorites shows only minor variation (CnG: 10.9 ± 0.5‰ (2σ), AD1: 11.7 ± 0.6‰ (2σ)) within single populations, with no evidence of mixing. Quartz–zircon isotopic disequilibrium is consistent with later crystallisation of quartz from late magmatic fluids, and in case of the AD1 diorite after the inferred magma mixing from a homogenised, higher δ¹⁸O melt.

High-precision SIMS oxygen isotope analysis of zircon provides a new approach to identifying and resolving previously undetected early-stage magma mixing and constraining the compositions and origins of the component magmas. A combination of zircon, quartz and whole-rock data has proven to be a powerful tool in reconstructing the petrogenetic evolution of diorite from early crystallisation to late alteration.     

Thermal segmentation along the N. Ecuador–S. Colombia margin (1–4°N): Prominent influence of sedimentation rate in the trench

Along the deformation front of the North Ecuador–South Colombia (NESC) margin, both surface heat flow and trench sediment thickness show prominent along-strike variations, indicating significant spatial variations in sedimentation rate. Investigating these variations helps us address the important question of how trench sedimentation influences the temperature distribution along the interplate contact and the extent of the megathrust seismogenic zone. We examine this issue by analysing 1/ a new dense reflection data set, 2/ pre-stack depth migration of selected multichannel seismic reflection lines, 3/ numerous newly-identified bottom-simulating reflectors and 4/ the first heat probe measurements in the region. We develop thermal models that include sediment deposition and compaction on the cooling oceanic plate as well as viscous corner flow in the mantle wedge. We estimate that the temperature from 60–150 °C to 350–450 °C, commonly associated with the updip and downdip limits of the seismogenic zone, extends along the plate interface over a downdip distance of 160 to 190 ± 20 km. We conclude that the updip limit of the seismogenic zone for the great megathrust earthquake of 1979 is associated with low-temperature (60–70 °C) processes. Our models also suggest that 60–70% of the two-fold decrease in measured heat flow from 3°N to 2.8°N is related to an abrupt southward increase in sedimentation rate in the trench. Such a change may potentially induce a landward shift of the 60–150 °C isotherms, and thus the updip limit of the seismogenic zone, by 10 to 20 km.     

Clonal adaptation of cancer cells in flatfish liver to environmental contamination by changes in expression of P-gp related MXR, CYP450, GST-A and G6PDH activity

Progression from eosinophilic foci to persistent basophilic foci and carcinomas was observed in pollution-induced hepatocellular carcinogenesis in European flounder (Platichthys flesus L.) in a similar sequence as in chemically induced liver cancer in mammals. Image analysis was used to quantify enzyme activity and protein expression as visualised by enzyme and immunohistochemistry in various stages of toxipathic lesions and carcinogenesis. In eosinophilic foci, growth advantage was achieved by increased production of NADPH and pentoses for biosynthesis and cell proliferation due to increased G6PDH capacity during the first steps of clonal adaptation. Simultaneously, oxyradical production by CYP450, phase I was reduced. Overexpression of P-gp mediating multi-xenobiotic resistance was noted in basophilic cell types which persisted during progression towards carcinomas. This was accompanied by increased protein levels of oxyradical scavenging GST-A. These changes are consistent with adaptation and phenotypic expression of the multidrug or xenobiotic resistance (MDR/MXR) type in hepatocarcinomas of European flounder.     

Structural Studies of a UDP-glucuronosyltransferase gene from the plaice (Pleuronectes platessa)

A partial length cDNA coding for the putative PAH-inducible phenol-conjugating UDP-glucururonosyltransferases (UGT) isoform of plaice was used to isolate overlapping clones from a plaice genomic library. Sequence analysis revealed the presence of a complete gene spanning 4.1 kb for a plaice UGT which showed a strong conservation in exon structure, amino acid character and amino acid sequence with mammalian UGT1 family genes, although additional alternative upstream exon 1s were not identified in the present study. Southern blot analysis revealed a low copy number for the gene and some degree of structural polymorphism in gene structure between individuals. This was also reflected in the finding that there were significant variations between the nucleotide sequences of the plaice gene and the cDNA previously isolated from a different individual fish. Future studies will investigate the possibility that there may be phenotypic variations which could lead to alterations in susceptibility to pollutant toxicity.     

A piscine glutathione S-transferase which efficiently conjugates the end-products of lipid peroxidation

A cDNA clone for glutathione S-transferaseA (GSTA) from plaice (Pleuronectes platessa) was expressed in Eschericia coli (E. coli) and purified to homogeneity by S-hexylglutathione affinity chromatography. When compared to literature values for a variety of purified mammalian GSTs, the heterologously expressed purified plaice enzyme had moderate activity towards the model substrate 1,2-chloro-2,4-dinitrobenzene (CDNB) and exhibited a Km of 2.5 ± 2 mM and Vmax of 30.9 ± 2.3 μmol min⁻¹ mg⁻¹. It had little or no activity towards several other model GST substrates including 1,2-dinitrochloro-4-benzene (DCNB), ethacrynic acid (EA), and p-nitrobenzylchloride (NBC). However plaice GSTA was a relatively efficient catalyst for the conjugation of a series of alk-2-enals and alk-2,4-dienals and also 4-hydroxynonenal. The highest activity observed with this series of substrates was with trans-non-2-enal with a Km of 17.9 ± 2.2 μM and a Vmax of 3.01 ± 0.57 μmol min⁻¹ mg⁻¹. These unsaturated alkenals have been identified in cells and cell extracts as highly toxic products arising from peroxidation of unsaturated fatty acids particularly during periods of oxidative stress. Fish are relatively rich in polyunsaturated fatty acids and thus GSTA mediated conjugation may be an important mechanism for detoxifying peroxidised lipid breakdown products.     

Crystallization of the Little Three layered pegmatite-aplite dike, Ramona District, California

Subhorizontally layered pegmatite-aplite bodies are characterized by fine-grained, sodic to granitic aplite that is usually juxtaposed abruptly above by much coarser-grained, commonly graphic potassic pegmatite. Although well studied, there currently is little concensus as to how such dikes form. The Little Three dike near Ramona, California, is representative of such zoned bodies in this and other regions, and contains discontinuous miarolitic pockets near the base of the graphic pegmatite zone. Tourmaline, garnet, biotite, and muscovite show no changes in major- or minor-element compositions indicative of progressive magmatic fractionation until the immediate vicinity of the main miarolitic zone, where they record abrupt and extreme enrichments in Li, F, and Mn. There is no correlation of chemical changes in the dike with the appearance of small miarolitic vugs well below the main miarolitic zone, nor is there any indication that the aplite, graphic pegmatite, or miarolitic pockets represent separate magma injections. The chemistries of tourmaline, garnet, and micas, however, preclude conventional models of Rayleigh fractionation or traditional zone refining. Textural features and modeled cooling histories indicate that the dike cooled quickly and might have solidified partially or totally to glass before crystallization commenced. Geothermometry based on the compositions of coexisting plagioclase and homogeneous, nonperthitic K-feldspar indicates inward crystallization of the dike, from ∼400–435 °C at the margins to ∼350–390 °C within 20–30 cm of the pocket horizon, then a sharp decrease to 240–275 °C in the pockets where K-feldspar is perthitic. We interpret the feldspar geothermometry (except perhaps in the miarolitic cavities) to reflect the temperatures at crystallization fronts that advanced into the pegmatite, first from the foot wall and eventually joined by a similar front downward from the hanging wall. Crystallization down from the hanging wall may have commenced after ∼70–80% of the foot wall aplite had crystallized. The very abrupt increases of Li, Mn, and F in tourmaline and garnet near the miarolitic zone appear to be explained best by the process of constitutional zone refining, in which a fluxed crystallization front sweeps an incompatible element-enriched boundary layer through a solid or semi-solid. After these two highly fluxed boundary layers merged near the main miarolitic zone, compositional evolution could have proceeded by crystal-melt fractionation. Received: 24 March 1998 / Accepted: 10 March 1999     

Glacial Geomorphologic Maps of Llanquihue Drift in the Area of the Southern Lake District, Chile

We present four glacial geomorphic maps of Llanquihue drift in the region of the southern Lake District, Seno Reloncaví, and the eastern half of northern Isla Grande de Chiloé, Chile. These maps form the basis of an interdisciplinary research project to establish a paleoclimate reconstruction of the last glacial cycle in the middle latitudes of the Southern Hemisphere. Therefore we stressed morphologic rather than lithologic units in our mapping program in order to delineate the glacial geomorphic forms that are surface manifestations of former ice-marginal fluctuations. The resulting maps show the lobate shape and low surface slopes of the former piedmont glaciers that, at the last glacial maximum, spread westward from the Andes into the Valle Centralto fill Lago Puyehue, Lago Rupanco, Lago Llanquihue, Seno Reloncaví, Golfo de Ancud, and northern Gulfo Corcovado. These maps are the framework to tie together in this volume the stratigraphic sections and radiocarbon samples from within the Llanquihue moraine belts as well as the pollen cores from surface mires on the belts.     

Moraine Exposure Dates Imply Synchronous Younger Dryas Glacier Advances in the European Alps and in the Southern Alps of New Zealand

Samples taken from the top surfaces of boulders on the Lake Misery moraines at Arthur's Pass, in the Southern Alps of New Zealand, were analysed for ¹⁰Be by accelerator mass spectrometry. Exposure ages calculated with the currently accepted production rate, along with scaling corrections for sample latitude and elevation (42°50'S, 960 m), are: 9300 ± 990, 11,000 ± 1360, 11,410 ± 1030, 12,050 ± 960, and 12,410 ± 1180 years. We consider the date of 9300 years to be an outlier, not included in our mean exposure age of 11,720 ± 320 years for the Lake Misery moraines. Based on exposure ages and geomorphologic similarities, we compare the Lake Misery moraines with an Egesen moraine complex at Julier Pass in the Swiss Alps (46°30'N, 2200 m). Based on the ¹⁰Be, ²⁶Al, and ³⁶Cl exposure ages of three boulders, we calculate a mean exposure age of 11,750 ± 140 years for the outer Egesen moraine at Julier Pass. Based solely on ¹⁰Be measurements, we obtain a mean exposure age of 11,860 ± 210 years for this outer moraine. Egesen moraines in the Swiss Alps represent glacier readvance during the Younger Dryas cold reversal, based on regional correlations and on basal radiocarbon dates from bogs located up-valley of Egesen moraines. The exposure dates from Arthur's Pass and Julier Pass show synchronous glacier advances both in the Southern Alps and in the European Alps during the European Younger Dryas chronozone of Mangerud et al .