TECTONIC SIGNIFICANCE OF STRATIGRAPHIC AND STRU ~ CT URAL CONTRASTS BETWEEN THE PURCELL ANTICLINORIUM ANC THE KOOTENAY ARC , EAST OF DUNCAN LAKE
The main goal of this study is to elucidate the wture and tectonic significance of the profound stratigraphic and struttural changes that occur between the crest of the Purcell anticlinorium and the Kootenay Arc. Reconnaissance (12.50 000) mapping by Reesor (1973) outlined conspicuous contrasts between the thick hasal Paleozoic (Hamill-Badshot) succession that overlies the Windermere Supergroup in the western Purcell Range and the thin, condensed early Paleozoic succession with overlapping Upper Devonian strata that occurs in the eastern Purcell Range. Reesor also described the abrupt contrast between the tight upright fold structures in this area and the refolded, west-verging, recumbent isoclinal folds that occur immediately to the west in the Kootcney Arc. He also showed that several small granitic plutons in the area probably were emplaced while the folding was still underway. The rocks exposed in this area (Figure 1-l-l ) record both the Late Proterozoic early Paleozoic birth and development of the Cordilleran miogeoclinal passive margin of North America (Bond and Kominz, 1984; Bond of a/., 1983, and the late Mesozoic -early Cenozoic deformation, regional metamorphism and granitic plutonism resulting from “collisions” between North America and a series of allochthonous terranes that have been accreted to it (Monger et al., 1982). Detailed geological mapping (I:50 000 and greater) was completed during July and August of 199 I and 1992 within an area of about 900 square kilometres in the western Purcell Mountains, between Duncan Lake and the headwaters of Tohy and Jumbo creeks (Figure I-I-2). This work will link the detailed mapping along the Kootcnay Arc by Fyles (I 964) to the detailed mapping by Root (I 987) and Pope (1990) in the central and eastern Purcell anticlinorium. The main objectives of this study are: (I) to establish the nature and tectonic significance of the stratigraphic rclationships within the thick sequence of Windermere, Hamill and Badshot strata in the study area; (2) to investigate the stratigraphic and tectonic relationships between these strata and the condensed onlapping early Paleozoic succession that occurs on “the Windermere high” to the east. below the Mount Forster thrust fault in the central and eastern Purcell Mountains (Root, 19X5: Reesor, 1973); (3) to establish the nature, evolution and regional tectonic significance of the change in structural style between the study area and the adjacent areas in the Kootenay Arc and in the central Purcell Mountains; and (4) to invest&ate the relation ship hetaeeo the initial structural configuration of the rifts d margin and the major structures that develc#ped during Me iozoic tenam: accretion and deformation of the margin.
Structure and Metamorphism
The Brioverian formations of the Armorican Massif have been involved in orogenic events generated by the plate tectonic regime during latest Proterozoic-Early Cambrian times; these gave rise to the Cadomian fold-belt which is contemporaneous with the Pan-African (sensu lato) and Avalonian progenies.
On the use of the Hardening Soil Small Strain model in geotechnical practice
This article highlights the importance of using advanced constitutive soil models in numerical modelling as daily geotechnical practice. In this context, the Hardening Soil (HS) model is presented as the most advanced soil model implemented in the ZSoil finite element code. The article recalls the basic features of the HS model and it explains their role in numerical simulations. The role of pre-failure non-linear behaviour of soils is also discussed. An application of the HS model is illustrated on typical geotechnical problems such as retaining wall excavation, tunnel excavation and undrained loading followed by consolidation.