Academic literature on the topic 'Sedimentation and deposition Victoria Western District'

The onset of the Jurassic sedimentation in the region of Pernik (southwestern Bulgaria) is at the end of Bajocian with deposition of sandstones (Lyalintsi Member of Gradets Fm.) and continuing during the Bathonian with bioclastic limestones (Polaten Fm.). The section Staro selo is one of the most complete Jurassic sections in Southwest Bulgaria. It is studied from several points of view: lithofacial, depositional processes, biostratigraphic and sequence stratigraphic. In Bajocian-Bathonian interval four 3rd order depositional sequences are individualized: Bj 5, Bat 0, Bat 1 and Bat 2. After a break of sedimentation (Callovian-Oxfordian), the limestones of Gintsi (Lower Kimmeridgian) and Drugan (Middle Kimmeridgian) Formation were deposited in which 3 depositional sequences were recognized (Kim 2-Kim 4). Nineteen depositional sequences of 3rd order are individualized (Kim 5-Ti 1.1-Ti 1.13, Ti 2, Ti 3.1-Ti3.2, Ti 4, Ti 5) in the sediments of Neshkovtsi Formation (Upper Kimmeridgian) and in the Bobovo Member of Kostel Formation (Uppermost Kimmeridgian – Upper Tithonian in the studied area). The recognition of the depositional sequences is based chiefly on the geometry and the superposition of the calcareous and siliciclastic sediments. The divided depositional sequences are compared to those of Western European scheme of Hardenbol et al. (1998). Within the carbonate part of the succession they are of the same number and in the siliciclastic part they are more numerous.

The pre-Callovian stratigraphic gap in the Central Balkanids is distributed in the Etropole, Teteven, Troyan, Kazanluk, Gabrovo and Turgovishte Districts. To the west (village of Gintsi, Sofia District) and to the east (the section of well R-3 Yunak, District of Yarn a) of the gap uninterrupted Bathonian-Callovian rock successions exist. In its western and eastern parts the pre-Callovian stratigraphic gap is a diastem. In these localities the gap embraces minimum duration. In the western diastem the duration of the gap is from the Late Bathonian to the Early Callovian. In the eastern diastem the duration of the gap is probably in the framework of the Late Bathonian. In many localities where the gap is diastem the boundary between the basement and the cover is marked by hardgrounds. In its central part (Troyan, Kazanluk and Gabrovo Districts) the pre-Callovian stratigraphic gap is with much longer duration. This is caused by the intensive submarine washout of the earlier deposited Middle and Lower Jurassic sediments. In limited localities the Callovian from the cover lies directly even above Upper Triassic rocks. Almost everywhere the cover of the gap is represented by condensed Middle-Upper Callovian micritic limestones. They are rich of ammonites. The main microfacies type is mudstone/wackestone with filaments from thin-shelled bivalves. It is correlated with the Standard Microfacies Type 3 (SMF 3) - "pelagic mudstone and wackestone". It is formed in the lower part of the deep sublittoral, which is in consent with the ba thymetric interpretations based on the characteristics of the respective faunal spectra. The Callovian limestones in conditions of uninterrupted sedimentation show similar microfacies characteristics. In the localities where the pre-Callovian gap is a diastem, the conclusions for the microfacies characteristics and for the faunal spectra of the Bathonian sandy bioclastic limestones are similar. The microfacies type is bioclastic-lithoclastic packstonelrudstone, which can be attributed to some extent to the SMF 4 - "bioclastic-lithoclastic packstone". It may be supposed that the features of this texture direct to a more shallow parts of the deep sublittoral. Almost the same characteristics have the Bathonian limestones and marls in conditions of uninterrupted sedimentation. In general, the pre-Callovian gap is realized in submarine conditions, which are connected with the deep sublittoral. There are four stages in the transition between normal sedimentation and submarine gap: normal sedimentation (in which biostratigraphic superposition is traceable) → slow sedimentation (condensations) → submarine stratigraphic gaps (as a result of non-deposition - diastems) → submarine stratigraphic gaps (as a result of submarine washout).

The Midway sequence is an assemblage of subaerially deposited clastic and volcanic rocks that forms a narrow wedge within Neoarchean greenstone of the western Wawa subprovince of the Superior Province. Volcanic conglomerate in the Midway sequence contains clasts of stratigraphically older greenstone, together with clasts of a distinctive hornblende-phyric trachyandesite that is not represented among the older greenstone flows. The trachyandesite forms flows and pyroclastic units that are interbedded with lenticular deposits of volcanic conglomerate in a manner interpreted to indicate approximately coeval volcanism and alluvial fan - fluvial sedimentation within a linear, restricted, and tectonically active depocentre. The Midway sequence unconformably overlies greenstone on one side and is bounded by a regional-scale, strike-slip fault on the other. Structural analyses show that the Midway sequence was deposited after an early, precleavage folding event (D1) in greenstone, but before the regional metamorphic cleavage-forming D2 deformation. Lithologic and structural attributes are consistent with deposition in a strike-slip "pull-apart" basin. The stratigraphic and structural characteristics of the Midway sequence are generally similar to those of the Timiskaming Group and Timiskaming-type rocks in Canada, and more specifically to those of the Shebandowan Group in the Thunder Bay district. This similarity implies that the latest Archean tectonic and magmatic history of the western Wawa subprovince may have been nearly synchronous over great distances.

The promotion of sedimentation by mangrove ecosystems with adequate sediment supply has been well documented. However, predicting the amount of accretion or erosion at a specific point, is difficult due to the inherent stochasticity of sediment movement and deposition. Forcings which have been thought to influence short-term sedimentation rates, such as the amount of suspended matter in the incoming water, the wave regime at the site, elevation above sea level, distance from the low tide mark, and vegetation density, were investigated using large arrays of erosion pins at five sites around Western Port, Victoria over the course of one and a half years. We analyzed large scale/short-term and small-scale/longer-term vertical displacement within and between sites, and quantified small-scale intra-site variability. Results show, that while all study sites within Western Port were accreting sediment, they were not doing so at the same rate, and both intra-site and inter-site variability is high. Short-term large-scale or site wide analysis shows that total suspended matter and significant wave height (SWH) did not significantly affect vertical displacement rates. Surprisingly, neither distance from water nor vegetation density significantly affected vertical displacement or explain the spatial distribution of accretion and erosion within the sites. The coefficient of variation at each pin shows that there is high temporal variability in vertical displacement at each location, with individual pins alternating between erosion and accretion over time. Our study finds that while large scale (1 km2) patterns of sedimentation are temporally consistent, small scale patterns (< 100 m2) are difficult to predict. This small-scale stochasticity therefore compounds management of mangrove ecosystems, especially as it relates to predicting the response to sea level rise. Thus, investment in small scale management of vegetation density, or microtopography, is perhaps not required for overall shoreline stability with sea level rise and blue carbon accumulation, making ecosystem restoration more feasible where resources are limited. However, at larger, forest-wide, spatial scales a higher level of predictability exists such as the overall response of the coastal tract to prevalent wave energy and sediment supply.

The eastern Karakoram lies to the north of the Shyok ophiolite melange belt (commonly known as the Shyok Suture). Metamorphic rocks are limited in occurrence and mainly confined to the either side of the batholith. Sedimentation history of the Karakoram Basin or the Karakoram Tethys spans from Carboniferous to post-Cretaceous and was confined to the north of the Karakoram Batholith. To the north and east, this basin was not confined to the Karakoram Range but extends beyond its limits. Lower part of the sedimentary sequence is dominated by argillites, siliciclastics and carbonates of Carboniferous to Permian. Basic to intermediate lava flows, sometimes with large pillows, are commonly associated with these sediments particularly in the eastern part of the area. Upper part of the basin, exposed to the north of Chhungtash and extending beyond the Karakoram Pass, is dominated by the carbonates. The end phase of deposition in the Karakoram Tethys is marked by coarse elastic deposits of molassic nature during the post-Cretaceous period. The Karakoram Batholith defines the southern limit of the Karakoram in its eastern part. In the north it intrudes the metamorphics and lower part of the Karakoram Tethys. Along the southern margin the granitoids have intruded the Shyok ophiolitic melange and metasediments. Compositionally, the granitoids of the batholith varies from tonalite to granite which become porphyritic to the south. Magmatic activity within the batholith and also in the Karakoram Tethys ended with the intrusion of a variety of dykes within the batholith. Some of the recent workers working on the Western Karakoram region (from Pakistan side) considered the origin of theKarakoram batholith primarily due to a complex combination of subduction and tectonism. According to them, initially the granitoids were generated by a subduction along the Pamir Suture, subsequently by a subduction along the Shyok Suture and final phase came due to collision. However, present study in the eastern Karakoram points out the emplacement of the batholith along the interface of oceanic and continental margin. The Karakoram batholith is very far from the Pamir Suture. Therefore its origin cannot be related to the subduction along the Pamir Suture. The batholith is very young and has come at the time when Ladakh Batholith was emplaced or at a later date.