Alina Shchepetkina

Alina Shchepetkina
University of Lisbon | UL · Faculty of Science

PhD

About

20
Publications
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88
Citations

Publications

Publications (20)
Article
The Lower Cretaceous McMurray Formation contains crude bitumen reserves of the Athabasca Oilsands that formed by channel amalgamation and lateral migration of fluvio-tidal point bars. These point bars are widely accepted as incised valley fills during episodic base-level rises in tidally influenced estuary (Mathison, 2004; Boyd et al., 2006; Hein e...
Article
The upper Valanginian – lower Aptian Centenario Formation is a significant producer of oil and gas in the Neuquén Basin, western Argentina. This formation is located exclusively in the subsurface of the eastern and northeastern Neuquén Basin, and is 450–1000 m thick. The Centenario Formation laterally interfingers with the Agrio Formation. Previous...
Article
The fluvio-tidal transition zone (FTZ) is sedimentologically and ichnologically complex, encompassing variable sedimentary facies. Published research on the FTZ implies a wide range of physical and chemical conditions as well as resultant sedimentary structures. Variable definitions and terms have been applied to this transition zone for decades. T...
Conference Paper
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The upper Valanginian-lower Aptian Centenario Formation is an important producer of oil and gas in the Neuqeun Basin, western Argentina. The formation is located exclusively in the subsurface of the Neuquen Basin, and averages 450-1000 m in thickness. The Centenario Formation is defined as lateral continuation of the Agrio Formation. The previous s...
Conference Paper
Full-text available
The middle McMurray Formation is a stratigraphic unit of great economic interest in northeastern Alberta (Canada), and has been extensively studied by academics and industry alike. The paleoenvironments represented by the middle McMurray Formation have been actively debated within the last few decades. Two current interpretations of its paleodeposi...
Article
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This paper provides an overview of the history of ichnology from both Russian and international perspectives. However, the main purpose of the paper is to review how trace fossils can be used to discern the brackish-water sedimentary environments from their open-marine counterparts. A number of modern studies are presented, including: (1) Kouchibou...
Article
Full-text available
Recognition of facies differences across the fluvial reach into the fluvio-tidal transition zone and the inner estuary can significantly contribute to reliable subsurface facies interpretation and modeling. The fluvio-tidal transition (FTZ) in estuaries is a sedimentologically complex zone, where fluvial and tidal currents interact, inducing abrupt...
Article
The paleoenvironments represented by the middle McMurray Formation have been actively debated within the last few decades. Highly detailed core studies have investigated the ichnology of the middle McMurray to gain insight on the paleodepositional conditions of these sediments. However, oil saturation makes diagnostic sedimentary and biogenic featu...
Article
Mud floccule ripples, small mud rip-up clasts, erosional scars and tool marks are reported for the first time from the macrotidal Petiticodiac River estuary, New Brunswick, Canada. The ripples occur on the intertidal flats and are ebb-oriented. Observations have been conducted during the spring low tide at high-river and low-river discharge. Floccu...
Article
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Fine-grained sediment deposition is often conceived to happen in still water conditions and to represent slow sedimentation rates. However, it has been increasingly noted that mud sedimentation commonly occurs under high-energy conditions. The macrotidal Petitcodiac River estuary is used as an example to investigate the significance of flocculation...
Article
Through the integration of sedimentological and ichnological observations, this paper explores the character of sediments deposited across the fluvio-tidal transition zone of the upper microtidal, mixed-energy, sand-dominated Ogeechee River estuary, Georgia, USA. A transect of tidally influenced to fluvial channel-bars and their facies variability...
Conference Paper
Full-text available
Recognition of differences in the sedimentological character of sediments deposited within the tidally influenced inner estuary and fluvio-tidal transition zone can significantly aid in subsurface facies identification. The Ogeechee River Estuary serves as an excellent modern analogue of a sand-dominated micro-to mesotidal estuary. Sedimentological...
Article
Despite the abundant well-log and core data available for the McMurray Formation, the succession has remained difficult to interpret. Presently, a fundamental aspect of understanding the depositional nature of the McMurray Formation is whether or not the formation is dominantly estuarine or fluvial. Focussing on the informal middle McMurray, our de...
Article
The study provides a detailed description of mud-dominated sedimentary fabrics and their application for the rock record within the inner estuary to the fluvial zone of the Petitcodiac River estuary, New Brunswick, Canada. Sedimentological characteristics and facies distributions of the clay- and silt-rich deposits are reported. The inner estuary i...
Article
Full-text available
Obtaining sediment samples in unconsolidated sediment presents many challenges. The locale substrate can be soft, penetration of the sediment may be limited, preservation of the sedimentary fabric may be incomplete, and extraction of the sample may be difficult. Some of these issues are overcome with vibracore or suction-core techniques. Vibracorin...
Conference Paper
Full-text available
Identification criteria and interpretation of estuary-associated, mud-dominated sedimentary fabrics and their application for the rock record are explored in the study. Sedimentological characteristics and facies distribution of the clay- and silt-rich deposits within the Petitcodiac River Estuary are presented. The research is focused on the inner...
Conference Paper
Full-text available
Within the reaches of the Petitcodiac estuary abundant fluid mud containing 24-67% clay is observed. The considerable amounts of clay contribute to the formation of creeping fluid-mud sheets and viscous streams on the tidal flats. Larger proportions of silt and sand in the deposits with lesser amount of clay fraction (6-23%) are associated with the...
Conference Paper
Full-text available
More sedimentological and ichnological research in the mud-dominated reaches of estuaries is needed to better understand the rock-record expression of inner-estuary deposits. Mud-dominated estuaries are under-represented in the literature, perhaps because muddy locales are delicate and difficult to work on. Another reason for the lack of muddy estu...
Conference Paper
Full-text available
Exposed reaches of bays and foreshore zones are usually subject to harsh physical conditions that are unfavourable to multiple fauna. However, many macrofauna have skillfully been able to adapt to such tumultuous environments. The erosive nature of these environments are thought to have poor preservation potential, although they may in actuality be...
Conference Paper
Full-text available
The Lower Cretaceous McMurray oil sands contain inclined heterolithic stratification (IHS), which formed due to lateral and locally vertical accretion within channels. Variable interpretations as to the depositional affinity of IHS have been put forth, and these range from fluvial to middle estuary. This paper attempts to integrate ichnological and...

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