Department of Geology

Seminars & Events

The Department of Geology regularly hosts internal and external speakers during the academic year. Most talks are open to the public. For the most up-to-date information on upcoming events, please consult the list below or follow us on Twitter.


 

2018-2019 Seminar Series


 Dipicolinic acid as a tracer for oil seeps in marine sediments

 

Dr. Jayne Rattray, Energy Bioengineering and Geomicrobiology Group,

University of Calgary

 

Monday, September 17 @ 11:30AM

Science 411

 

Understanding the sediment biogeography of dormant marine thermophilic bacterial endospores (thermospores) has the potential to assist locating and characterising working petroleum systems. The presence of thermospores in cold ocean environments suggests that distribution occurs via hydrocarbon seepage from thermally active reservoirs. Low abundance and endospore coat physiology mean nucleic acid based techniques have limited success for in situ detection of  hermospores. The biomarker 2,6-pyridine dicarboxylic acid (dipicolinic acid or DPA) is specific to endospore-forming bacteria from the phylum Firmicutes, and constitutes a significant percentage of endospore dry weight. DPA is therefore a potential biomarker for sediment dwelling thermospores and hydrocarbon rich thermal seeps however its suitability for seabed screening surveys has so far not been tested. DPA distribution was assessed in surface sediment samples at 97 locations in the Eastern Gulf of Mexico and results from both oil positive and oil negative sites were compared. Recent expeditions in Canadian waters to the Scotian shelf and Laurentian channel have provided both oil positive and negative sediment cores, and enabled higher resolution down-core DPA depth profiles. In this seminar we showcase our findings investigating the efficacy of DPA as a biomarker for tracing thermospores and oil seeps in marine sediments.

 


 

Hypervelocity impact effects on Earth: Causes, consequences and future threats

 

Dr. John Spray, Planetary and Space Science Centre, 

University of New Brunswick, Fredericton

 

Thursday, October 18 @ 1:00PM

Science 411

 


Hypervelocity impact effects in our Solar System are now widely appreciated as having contributed to fundamental planet-building and planet-modifying processes throughout geological time. The strain rates at which impact events take place are exceptional relative to the timescales of most geological processes with which we are familiar. Hypervelocity impact can cause intense shock loading resulting in melting, vaporization and even plasma formation in target rocks. Further from the contact and the compression locus (>50 GPa), shock waves cause local melting and solid-state phase transformations with the creation of new structural states and mineral polymorphs. An overview will be presented with emphasis on terrestrial impact cratering. Approximately 200 impact structures are now proven on Earth, which is a shadow of its true historical record. This paucity of craters is due to Earth being an active planet and it having erased the majority of past impact evidence due to plate tectonics, volcanic activity, burial and erosion. Nevertheless, valuable examples have survived: we will tour some of them and explore the intriguing products of hypervelocity impact as we strive to understand these extreme processes. We will also consider the future and what threats are posed to our social infrastructure by asteroids and comets colliding with Earth.

 


 

2018-2019 GAC Howard Street Robinson Lecture Series

The Precambrian Secrets of Yukon

Howard Street Robinson Medalist

 

Dr. Derek Thorkelson, Department of Earth Sciences,

Simon Fraser University

 

Thursday, November 8 @ 1:00PM

Science 411

 

Announcement

 

Most geologists in Canada regard the Canadian Cordillera as a Phanerozoic orogen consisting of fold belts and accreted terranes rich in precious and base metal deposits, and flanked by the modern Cascadia subduction zone. To the surprise of many, the orogen also preserves a rich Precambrian history that spans over a quarter of Earth history. The most extensive Precambrian exposures are preserved in structural culminations in Yukon Territory. Few academic researchers have worked in these vast and mysterious mountains, and it has taken decades to unlock their geological secrets. Although each step was important, our most revealing strides have come in the past few years. We have developed a new, deeper understanding of how northwestern Canada evolved during the Proterozoic and participated in the construction and break-up of the supercontinents Nuna and Rodinia. This talk will provide a backdrop of information followed by recent research highlights including our new model of Proterozoic terrane accretion, and a glance toward future research. 

 


 

Science Atlantic-AGS Speaker Tour

Forensic petrology applied to the Titanic headstones

 

Dr. Barrie Clarke, Department of Earth Sciences, 

Dalhousie University

 

Tuesday, November 20 @ 1:00PM

Science 411

 

Announcement

 

All but one of the 150 victims of the Titanic disaster buried in Halifax, Nova Scotia, have petrologically identical gabbro (“black granite”) headstones. After being in place for nearly a century, one headstone had become damaged, so the City of Halifax sought to replace it; however, there was no historical or archival record of where these headstones had come from, and thus the solution as to their place of origin had to be determined scientifically. Just as DNA is unique to each living thing, so every rock also has a unique set of characteristics (age, minerals, texture, and chemical composition) that sets it apart from every other rock. Ideally, the headstones should match only the quarry where they were extracted. But there are tens of thousands of quarries in the world, so which was the right one? This presentation describes how, using the best sleuthing techniques of Sherlock Holmes and CSI combined with multivariate statistics, we located the source quarry in southwestern New Brunswick.

 


 

Active Marine Geohazards on the seafloor of Eastern and Arctic Canada

 

Dr. Alexandre Normandeau, Research Scientist, Marine Geoscience

Geological Survey of Canada, Bedford Institute of Oceanography

 

Thursday, November 22 @ 1:00PM

Science 411

 

 Announcement

 

Submarine landslides and turbidity currents are gravity flows that transfer large amounts of sediment and organic carbon to the deep-sea. They represent major geohazards as they can sever fiber-optic communication cables, rupture subsea pipelines, and damage oil and gas infrastructures. Thus, an understanding of where, when and how they occur is critical to mitigating their impact. Because there are so few direct observations of turbidity currents and submarine landslides, the factors responsible for triggering them are poorly known and understood. This presentation will illustrate the controls governing the most recent and active geohazards observed on the seafloor of both eastern and Arctic Canada. In eastern Baffin Island fjords, the behaviour of retreating glaciers dictates the presence or absence of turbidity currents on delta fronts. In southeastern Canada, glaciers are now absent, suggesting that most geohazards occurred during the late-Pleistocene when glaciers provided large volumes of sediment to the continental slope. However, new mapping of the southeastern Canadian shelf and margin has revealed recent giant landslides and active turbidity currents. Offshore of Nova Scotia, a submarine landslide deposit the size of Lake Ontario, triggered between 4 and 1.5 ka BP, was just discovered. Additionally, a monitoring program undertaken in the Gulf of St. Lawrence combining repeat mapping of the seafloor with acoustic doppler current profilers (ADCPs) revealed the recurring presence of turbidity currents that lead to the migration of bedforms on the seafloor. Geohazards in eastern and Arctic Canada, therefore, appear to be more active than previously thought; we need only look in the right locations with a fresh perspective!

 


 Genesis of polymetallic vein-type mineralization in the Freiberg district, Germany: Towards new exploration concepts in a historic mining district

 

Dr. Mathias Burisch, Department of Mineralogy

Freiberg University of Mining and Technology

 

Tuesday, January 29 @ 10:00AM

Science 411

 

 Announcement

 

Located in the Variscan metallogenetic province, the Freiberg district in Germany is marked by polymetallic and polystadial vein-style mineralization. Important mineralization stages include: Pb-Zn-Cu-Sn-quartz (I), Ag-Sb-carbonate (II), Pb-Zn-Cu-fluorite-barite (III) and Ag-Bi-Co-Ni-As-carbonate (IV) assemblages. Stages (I) to (III) have been of particular relevance for mining in a district that celebrated its 850’th anniversary in 2018 and which has given rise to some of the defining early work in the then emerging discipline of economic geology (e.g., Werner, 1791 and von Cotta, 1855).

When production in the Freiberg District ceased in 1967 it was for political reasons, with significant resource and exploration potential remaining. Efforts by junior companies in recent years to explore this potential have been stifled by the lack of modern metallogenetic concepts for the district. To start filling this gap, we carried out Rb-Sr geochronology and trace element analyses of sphalerite from different mineralization stages, in combination with microthermometric studies on fluid inclusions in ore and gangue minerals. Furthermore, we carried out thermodynamic reaction path models to better understand mineral zoning in the Freiberg district. 


Petroleum Systems and Source Rocks of Atlantic Canada

 

Dr. Grant Wach

Professor of Petroleum Geoscience, Dalhousie University
Director, Basin and Reservoir Lab
2018 CSPG Slipper Gold Medal Recipient

 

Friday, March 8 @ 11:00AM

Science 411

 

 Announcement

 

The research conducted at the Basin and Reservoir Lab at Dalhousie University focuses on understanding Petroleum Systems through analyses of the sequence stratigraphy, depositional environments, tectonics, geo-pressure conditions, basin modeling and the provenance of sediment in basins. Source rock is a fundamental component of petroleum systems; coupled with reservoir distribution they are the two key risk elements of the Atlantic Canada margin. Previous studies (Beicip-Franlab, 201; CNSOPB 2013) proposed a model with a regional Lower Jurassic source rock extending beyond the Sable Subbasin, with an increased potential for new oil and gas discoveries.


Our team investigated source rocks in Atlantic Canada offshore within the Triassic-Jurassic time interval. We re-evaluated existing organic geochemistry datasets and completed new analyses of selected cores and cuttings and integrated these with time-equivalent source rock outcrops in Canada and conjugate margins of Morocco, Portugal, Spain and Ireland. Our investigations of known, probable and possible source rocks in the eastern Canada offshore shelf and deepwater offshore regions and knowing how these organic-rich intervals developed and evolved through time, will contribute to mitigating drilling and production risks and may aid to identify new exploration opportunities in the Scotian Basin and conjugate margins.


 Flaming Tapwater: The science behind the occurrence of methane in groundwaters overlying oil, gas and coalfields of North America

 

Dr. Owen Sherwood

Department of Earth Sciences
Dalhousie University

 

Friday, March 15 @ 10:30AM

Science 411

 

Announcement 

 

Horizontal drilling combined with hydraulic fracturing has revolutionized the onshore oil and gas industry. However, it has also raised serious concerns about the environmental impacts of oil and gas industry operations, especially with respect to groundwater quality. This seminar will cover the origins of microbial and thermogenic methane, which is the main component of combustible gas in flammable tap water; the occurrence of natural/in situ versus migrated/stray gas in groundwater; some examples of groundwater contamination in unconventional oil and gas fields; as well as some information about the ongoing Gas Seepage Project (GaSP) in the Maritimes.


 Looking down to look up: New approaches in the search for life in strange places

 

Dr. Greg Wanger

Consultant, NASA-Jet Propulsion Lab
Deep UV Raman and Fluorescence Spectroscopy

 

Friday, March 22 @ 11:00AM

Science 411

 

Announcement 

 

Looking for biosignatures on planets beyond our own requires that we first truly understand how life on Earth has left its mark. Examining extant microbial life in Earth’s deep subsurface has changed our understanding of the limits of life. The introduction of new Deep-Ultraviolet spectroscopic techniques (UV-Raman and fluorescence) allows us, for the first time, to accurately map and characterize organic compounds and microbes on mineral surfaces here on Earth. Now this ability will be put to the test on Mars with SHERLOC, a spectroscopic instrument set to fly on the Mars 2020 mission.


Evolution of the Oxford Sinkhole

 

Amy Tizzard

Regional Geologist
Geological Survey Division
Department of Energy and Mines

 

Wednesday, March 27 @ 11:30AM

Science 411

 

Announcement 

 

A small opening in the ground was first observed by groundskeeping staff at the Lion’s Parkland in Oxford, Nova Scotia on July 28, 2018. Over the following weeks the sinkhole slowly grew in both depth and diameter until a sudden collapse on August 20 gave rise to a period of rapid development in which the sinkhole grew quickly from a few meters in size to upwards of 40 meters in diameter and an unknown depth. Observations and measurements of propagation cracks encompassing the sinkhole demonstrate a progression to the northeast toward playground infrastructure and surrounding Salt Lake. Aerial surveillance of surrounding lakes and watercourses during the most active period of sinkhole development showed no unexpected turbidity, indicating a lack of mixing of sinkhole water with that in surrounding waterbodies. LiDAR imagery of the area shows numerous dry and ponded sinkhole activity in the vicinity of Salt Lake and area to the southwest. The underground extent of the collapsed cavern is presently unknown, however the region is underlain by the Windsor Group formation, which is composed of interstratified red beds, evaporites and carbonate rocks that are prone to the development of sinkholes. Gypsum and salt have been documented in the area, however, no bedrock is visible at the sinkhole due to a thick deposit of sand. The sinkhole continues to slowly erode along its margins, however the rate of growth has significantly slowed.


Terrane concept and Cape Breton Island

 

Dr. J. Duncan Keppie

Institute of Geology
National Autonomous University of Mexico

 

Friday, March 29 @ 11:00AM

Science 411

 

Announcement 

 

A terrane is primarily defined as having a distinct, time-bounded, fault-bounded tectonostratigraphy that cannot be explained by facies changes. The geology of Cape Breton Island has been interpreted either as exposing a cross-section of the Avalon Composite terrane based upon its unique Cambrian-Ordovician overstep sequence, or, the current concensus that it represents a complete cross-section of the Appalachian orogen from Laurentia across two intra-Iapetan terranes (the Silurian Aspy terrane and Neoproterozoic Bras d’Or terrane) to Cambrian-Ordovician Avalonia. Crucial to the latter view is the presence of ca. 1 Ga plutons, including anorthosites, which have been regarded as correlatives of Grenvillian basement, a correlation that overlooks the fact that Avalonia is also underlain by a ca. 1 Ga basement. U-Pb zircon analyses from the Red River anorthosite (Blair River Complex, northwestern Cape Breton Island) previously dated as ca. 1.1 Ga have yielded 421 ± 3 Ma intrusive ages with older ages between 865 ± 18 Ma and 1044 ± 20 Ma inferred to be either xenocrysts derived from the country rock or from the source. Implications of these data suggest that the accompanying low pressure granulite-amphibolite facies metamorphism of the Blair River Complex is either the root of a 440-410 Ma, magmatic belt produced during slab break-off or relict ca. 1 Ga basement. The Blair River Complex occurs in a NNE-SSW, sinistral positive flower structure that progresses upwards from a Neoproterozoic rifted arc through a low grade upper Ordovician-Silurian overstep sequence to amphibolite facies fault slices, capped by the low-pressure, granulite facies rocks (Blair River Complex). Furthermore, Pb isotopic data suggest the Blair River Complex has Amazonian (≈Avalonia) affinities. Thus, Cape Breton Island, rather than representing a complete cross-section of the Appalachian orogen, is part of pristine—deformed Avalonia with a positive flower structure exposing a cross-section of Avalonian crust.