Strain patterns, décollement and incipient sagducted greenstone terrains in the Archaean Dharwar craton (south India)

The Archaean Dharwar craton is characterized by two greenstone successions: the > 3 Ga Sargur Group and the 3.0-2.5 Ga Dharwar Supergroup. Examples of both successions are described from the region of Jayachamarajapura where they are also distinguished by different tectonic patterns. The younger greenstones have undergone only minor deformation and are only slightly metamorphosed and so provide a good case study of the relative behavior of greenstones in relation to their granite-gneiss country rocks. A detailed structural analysis indicates two strain fields associated with two deformational episodes: D1 and D2. The D1 episode produced dome-and-basin structures and affected merely the older greenstones and the gneisses. The mapped strain field is compatible with the hypothesis that it is associated with the development of diapiric-type gravitational instabilities. The D2 episode affects only the younger greenstone belt, which has the overall geometry of a complex syncline. It is discordant over a complex of gneisses and older greenstones that was deformed during the D1 episode. The base of the discordant cover sequence is tectonized and constitutes a décollement surface. Kinematic criteria at this surface have opposite sense and converge towards the belt axis. These structural features are interpreted in terms of progressive deformation compatible with the incipient development of a sagducting trough. These results are consistent with those obtained from other parts of the craton, where the tectonic evolution appears to reflect mainly relative vertical displacements facilitated by the reheating of continental crust during two major Archaean tectonometamorphic episodes. Copyright © 1996 Elsevier Science Ltd

On the myology of the cephalic region and pectoral girdle of three arid species, <i>Arius heudeloti</i>, <i>Genidens genidens</i> and <i>Bagre marinus</i>, and comparison with other catfishes (Teleostei: Siluriformes)

The muscles of the cephalic region and pectoral girdle of Arius heudeloti, Genidens genidens and Bagre marinus are described and compared with those of non-ariid siluriforms. Our observations and comparisons revealed that, although the configuration of the cephalic and pectoral girdle musculature of these ariid species is basically similar to that of other catfishes, these species present two myological peculiarities that could eventually represent autapomorphic characters of the family Ariidae, namely: 1) the muscle adductor arcus palatini inserts not only on the mesial margin of the suspensorium, but also on a significant part of the lateral surface of this complex structure; 2) the adductor mandibulae Aw is obliquely oriented, with its postero-dorsal fibres being significantly dorsal to the upper edge of the coronoid process

Phylogenetic analysis of the pearlfish tribe Carapini (Pisces: Carapidae)

Fishes of the tribe Carapini (Encheliophis and Carapus) share a noteworthy peculiarity: they shelter in holothurian echinoderms or bivalve hosts. Some species are considered parasitic, others commensal. This study focuses on the phylogeny of the tribe, using two other Carapidae species as an outgroup (Snyderidia canina and Onuxodon fowleri). Insofar as possible, the selected anatomical and behavioural characters where chosen in an ecomorphological perspective, as features that could be responses to various lifestyle-related constraints. Our character selection also took into account the fact that some features are (presumably) linked. Such features were grouped together as a single trait to avoid their overvaluation.This methodology enabled commensals to be separated from parasites, the former belonging to Carapus and the latter to Encheliophis. Carapus species reflect in their morphology the constraints imposed by a diet of hard, mobile, elusive prey, showing predator-type features: a strong dentition, a wide mouth opening, a robust food intake apparatus. On the other hand, the endoparasitic Encheliophis species show a generally weaker buccal apparatus and narrow mouth opening, in relation to the different constraints of their lifestyle where the diet constraints are less pronounced: they eat body parts of their host. Changes in both generic diagnoses are proposed and three species are transferred from Encheliophis to Carapus

Archean granite-greenstone tectonics at Kolar (South India): Interplay of diapirism and bulk inhomogeneous contraction during juvenile magmatic accretion

[1] The structural study of the Kolar greenstone belt and surrounding granite-gneiss terrains combined with U-Pb dating reveals that the middle and lower crustal tectonoplutonic pattern of the eastern Dharwar craton developed during a major magmatic accretion event between 2550 and 2530 Ma. The granite-greenstone pattern resulted from the interference of gravity-driven sagging of the greenstones (i.e., diapirism), E-W bulk inhomogeneous shortening combined with horizontal N-S stretching, and syntectonic juvenile pluton emplacement. Bulk inhomogeneous contraction is accommodated by the synchronous development of a pervasive, N-S trending vertical foliation, shallow stretching lineation, and conjugate strike-slip shear zone pattern within and outside the greenstone belt, resulting in regional horizontal pure shear deformation. The plutons around the greenstone belt record regional contraction by developing one set of strike-slip C-S fabrics of the shear zone pattern. The development of the granite-greenstone pattern was coeval and compatible with deformation during juvenile magmatic accretion, melting, and granulite metamorphism in the lower crust. The Kolar example points to a specific crustal rheology that allowed sagduction of the greenstones and regional distributed bulk inhomogeneous strain, due to mechanical homogeneity and low viscosity provided by large-scale melting during the accretion event. This example further suggests specific boundary conditions to the craton that allowed E-W inhomogeneous shortening to be accommodated by N-S stretching and spreading of the crust without significant tectonic thickening. Such tectonoplutonic pattern is specific to the Archean and may develop as a consequence of mantle plume activity in intracontinental settings

Morphological particularities of the head in four Carapidae (Ophidiiformes)

A study of the skull and the musculature of the oral and pharyngeal region of four adult Carapidae species (Encheliophis boraboreruis, E. homei. E. gracilis and Carapus acus) has been undertaken to compare it with the diet related characters. The cephalic organization of E. boraborensis and E. gracilis seems related to diet (mainly fishes and shrimps for the first one and holothurian tissues for the other): these species are respectively commensal and parasitic. Although the feeding characters of E. homei and C. acus are closely similar to those of E. boraborensis, there are sparse observations of holothurian tissues in their stomach contents. It is suggested that these fishes are commensal when they are adults and have parasitic tendency when they are juveniles

Morphology of the <i>Buccal apparatus</i> and related structures in four species of Carapidae

The aims of this study were (1) to compare the morphology of the Buccal apparatus, the suspensorium and the opercle in four species of Carapidae (Carapus acus, Encheliophis boraborensis, Encheliophis homei and Encheliophis gracilis) and (2) to investigate the relationships between their cranial anatomy, their carnivorous diet, and their well known ability to enter holothurians.The complex and strong dentition and the wide hyomandibular with thickenings that seem to suit the constraints of the adductor mandibulae muscles partly inserted on the neurocranium are signs of a carnivorous diet.C. acus, E. boraborensis and E. homei have extremely strong buccal pieces and can protrude their upper jaws. However, in E. gracilis, the jaws are more slender, and the insertions of the Al along the entire length of the maxillary associated with the lack of mobility between the maxillary and the premaxillary prevent buccal protrusion. These differences could be related to the diet: C. acus, E. boraborensis and E. homei can feed on fishes and crustaceans, whereas E. gracilis feeds only on holothurian tissue.The cephalic morphology of the four species is not incompatible with entering the host. However, the neutralisation of the suboperculum spine by 'cartilaginous' tissue could be considered to be a particular adaptation to this behaviour

Comparative mapping of human chromosome 13 genes in the pig shows a similar gene arrangement

Previous comparative mapping between the human and pig genomes suggested complete conservation of human chromosome 13 (HSA13) to pig chromosome 11 (SSC11). The objectives of this study were comparative gene mapping of pig homologs of HSA13 genes and an examination of gene order within this conserved synteny group by physical assignment of each locus. A detailed HSA13 to SSC11 comparison was chosen since the comparative gene map is not well developed for these chromosomes and a rearranged gene order within conserved synteny groups was observed from the comparison between human chromosome 13 and bovine chromosome 12. Pig sequence tagged sites (STSs) for six HSA13 genes were developed and physically mapped using a somatic cell hybrid panel (SCHP) to SSC11 with 85–100% concordance. Fluorescent in situ hybridization (FISH) mapping also was applied to determine the gene order within each subchromosomal region. Results from this study increase the comparative information available on SSC11 and suggest the same gene order among examined loci on SSC11 and HSA13

Comparative mapping of human chromosome 3 genes in the pig shows different gene order

A comparative map of human chromosome 3 (HSA3) and pig chromosome 13 (SSC13) was constructed using physically assigned pig sequence tagged sites (STSs). Pig STS representing 11 HSA3 genes were developed and 10 pig STS were regionally mapped using a somatic cell hybrid panel (SCHP) to SSC13 with 80–100% concordance. Large-insert probes were obtained by screening a YAC library with primers for each STS. YACs were identified for DRD3, GAP43, PIT1, SI, and SST for fluorescent in situ hybridization (FISH) mapping. Single gene and bicolor FISH with each pairwise combination was used to further define gene order on SSC13. These data confrim chromosome painting results that showed HSA3 probes hybridize to a major portion of pig chromosome 13 and demonstrate extensive gene rearrangements within this conserved synteny group

Effectgerichte aanpak verwijdering P uit bodem- en slootwater duinzandgrond

Op bloembollenpercelen bij Egmond a/d Hoef worden twee zuiveringsmethoden getest om fosfaat te verwijderen uit bodem en slootwater. Het doel is het water te zuiveren van fosfaat om daarmee te voldoen aan de Europese Regelgeving voor de kwaliteit van oppervlaktewater