Sedimentary Geology Geos 240 Camosun College Dr Sedimentary Geology Geos 240 Camosun College Dr. Tark Hamilton Text: Sediments & Basins: Andrew D. Miall, 2006 Lab: Ancient Environments & the Interpretation of Geologic History , Lynn S. Fichter & David J. Poche, 3rd ed. 2001 Additional Lab support: American Geological Institute Laboratory manual in Physical Geology, 10th Ed. Richard M. Busch and Dennis Tasa

Sedimentary Products & Processes: Fraser Delta Aerial view of tidal creeks on the tidal flats of the Fraser River Delta at low tide. The creeks extend across approximately 100 m. Roberts Bank, Delta BC, Alexandra Shaw 2004. What is the drop in elevation if the slope is 0.25°? For small angles the angle in radians is approximately equal to the sine or tangent of the angle expressed in radians. What is a radian? 2Pi radians = 360° or Pi radians = 180° so… Slope of 0.25° x (3.14159 Pi Radians/180°) = 0.0004363 radians and Tan rise/run (0.0004363) = 0.0004363 metres = 4.363 cm drop At such low slopes and gradients, wind and currents can dominate over gravity and drainage. At high tide there was a NW-SE wind blowing parallel to Georgia Strait and the coast so oscillatory ripple marks formed in a several centimetres water depth. Once the tide ebbed, fortuitously the ripples were subparallel to the gradient and thus got reused to channelize the falling tide as tidal creeks. This same pattern can form over a few metres length and few cm fall all the way up to the scale of this photo with ripple marks a fer tens of cm high.

Sedimentary Products & Processes: Paleosols & Tephra Oblique view gully exposing paleosols and tephra from Mt. Hudson. Patagonia, Lago Buenos Aires Region, Argentina. Dr. Rene Barendregt, 2016. Sedimentary Products & Processes: Paleosols & Tephra Paleosols form over hundreds to thousands of years and are good climatic indicators. Tephra (wind blown volcanic ash layers) contain feldspars, biotite, hornblende or zircon which can be dated radiomentrically. Without tephra analysis, correlation and tephro-chronology, we would have no absolute ages for any of the stratigraphic column or geological periods!

Sedimentary Products & Processes: Volcano-Sedimentary Facies Eroded outcrop of cross bedded unconsolidated gravels and sands made of VRF’s. Chilled basalt flow margin intrudes and caps sequence. Argentina. Dr. Rene Barendregt, 2016. Sedimentary Products & Processes: Volcano-Sedimentary Facies It is clearer and truer to describe rocks for what they are: particle size, structures, compositions etc. Stick to the facts. Rather than what you interpret them to be. This stuff requires experience, models and several beer to figure out! These are Cross bedded dipping Gravels of volcanic provenance with quenched basalts that partially cap and partially crosscut them. Rene interpreted them as “fluvio-glacial” sediments (process of origin) cut by a basalt dyke. He studies glacial sediments as his specialty. I have seen many examples of basalt flows which entered rivers, quenched and blew apart the toe flow to gravel and even partially intruded and pushed around the soft unconsolidated sediments by their greater weight and density (2.7 > 2.2).

Sedimentary Geology Geos 240 – Introduction Chapter 1 Dr. Tark Hamilton Camosun College

SEDIMENTS = CSI EARTH!

Sedimentary Geology Geos 240: Dr Sedimentary Geology Geos 240: Dr. Tark Hamilton Sediments & Basins: Andrew D. Miall, 2006 Introduction: Why Study Sediments? Record of Earth History: environments, orbits, climate, atmosphere, sea level, physical processes Natural Resources: Building Stone; Aggregate; Hydrocarbons: Coal, Oil, Gas; Salts: Halite, Gypsum, Nitrates; SMS: Pb-Zn, Ground Water…

Folded & Faulted Upper Jurassic Coal-bearing Sediments Foothills, Canadian Rockies: Canmore Alberta

Basins: low lying areas for tectonic or erosional causes Sedimentary Geology Geos 240: Dr. Tark Hamilton Sediments & Basins: Andrew D. Miall, 2006 Introduction: Where to Sediments Occur? Basins: low lying areas for tectonic or erosional causes Under Water : Seas, Lakes, Rivers On Land: Deserts, By Glaciers, By Mountains From Weathering : Chemical, Mechanical From Transport : By Ice, Water, Wind, Mass Wasting

ISOPACH MAP Sediment Thickness in Km: Most of Geology is Sedimentary or needs to be explored through sedimentary cover. Isopach = contour map of constant thicknesses. No basin less than 2 km thick is worth drilling for oil and gas: Leaks away to surface, biodegrades, reservoirs breach. Geothermal gradients are too low ~15-25°/km so the sediments never got cooked enough to generate oil and gas Sediment Thickness in Km: Covers 60% of Earth > 500m, 13% > 10 km

Sedimentary Basins: Mackenzie-Beaufort Western Canada (Alberta - NE BC-Sask) Williston (Sask – Man – Mont -Dakotas) Appalachain, Michigan, West Texas, Green River North Sea Baltic Deep Marine: Pacific, Indian, Atlantic…

NORTH AMERICAN SEDIMENTARY BASINS Different provenances, different timings and tectonic processes. The Shield has been a sediment source for most of the age of the earth. The edge of the Canadian Shield against the Cratonic sedimentary cover is the greatest unconformity such as near Lake Athabasca or the Bottom of the Inner Gorge of the Grand Canyon. Grey is mostly passive margin extensional oceanic rift basins. Orange episutural includes rift and transcurrent extension (pull aparts) as well as compressional ups and downs.

What can various sediments reveal? Earth’s Oldest Rocks are FeCO3 ~ 3.75 Ga from Eastern Hudson’s Bay/Ungava Peninsula (N. Dauphas, S. Mojzsis & N. Cates 2007. Oldest Rocks Show How Earth May Have Dodged Frozen Fate of Mars, E.P.S. L.) Seasonal Occupation of a Late Middle Woodland Archeological Site (D.S. Brose 1994. The South Park Village Site and the Late Prehistoric Whittlesey Tradition of Northeast Ohio (Monogaphs in World Archaeology, Vol 20. 226p.) The effects of Site Selection, Sediment Supply, and Hydrodynamics:  A Case Study of Submarine Paleoseismology on the Northern  Cascadia margin, Washington USA Chris Goldfinger , Steve Galer , Jeffrey Beeson , Tark Hamilton , Bran Black , Chris Romsos , Jason Patton , C. Hans Nelson , Rachel Hausmann , Ann Morey., Marine Geology, July 2016. Carbonates reveal a CO2 + Methane atmosphere led Earth to Warming and ensured early liquid oceans Spring occupation: pollens, high water rugose fat mucket clams, humid snails versus fall occupation delciate lady finger low water clams and dry grassland snails. Holocene Paleoseismic record of Great Cascadia Earthquakes from the Accretionary wedge submarine canyons and deformation frontal slumps.

What can various sediments reveal? Proterozoic Orthoquartzites – Rodinia’s Super Continent Long lasting Desert Northern Hemisphere Harbour Sediments Worldwide : 1920’s – 1980’s Pb from gasoline Short Lived Radionuclides from Atmospheric Weapons Testing 1956-1964, more in northern hemisphere plus: metals, dioxins, pharmaceutical History of fluid motions in Sedimentary Basins 1.) Quartzites are mature, multi-cycle, continental. There were no land plants prior to Silurian and no forests prior to Devonian. 2.) Sites near human occupation and industrial activity bear the marks of our pollution and are the lasting environmental record therof. 3.) Atmospheric weapons testing through 1964 International Nuclear Test Ban Treaty dispersed short lived man-made, hot radionuclides throughout the atmosphere and deposited them adsorbed on clays to the fine grained sediments of the planet. 4.) if a sediment or sedimentary rock were like a white board. In its cements and fluids it records events after it is deposited. Think dirty dishes with red spaghetti sauce stains tellying of last nights’s supper They persist in recording environmental conditions through their mineral alteration, geochemistry, texture and isotopes!

CONCEPTS: Processes  Products Sedimentolgy, Stratigraphy, Diagenesis Environments, Groundwater Flow, Rock Properties Weathering, Cements, Concretions Upper photo: Cross bedded, dipping, colour banded, Jurassic Continental Desert Sandstone, e.g. Navajo Sandstone. Hematite & Limonite cements. Air oxidation Lower Photo: Mars Rover, “Blueberries” Concretions of Hematite, Fe2O3. Deflation surface. Oxidation by hard UV and higher energy radiation. No O2 or O3.

REGIONAL SETTING & FACIES ANALYSIS Jurassic Outcrops Recognizing a local stratigraphic succession allows one to predict what is uphill or downhill, or below surface accordingly. It also permits assignment of ages and detailed examination of lithology, facies and mapping as on the left. The Navajo sandstone is a good rock for cliff dwellings, scenery, subsurface aquifers etc. The Morrison is a great place to collect continental facies fossils: dinosaur bones, petrified wood etc. The other units are not so productive. Both the Navajo and the Entrada are cliff formers and weather resistantly as per the strip log. Which plateau would you walk to find the most fossils?

How do we study sediments, sedimentary rocks and sedimentary basins? Stratigraphy : Geophysics, Petrophysics, Boreholes Lithologies : Rock types, Geometries, Provenance Environments : Fossils, Sedimentary Structures, Minerals, Isotopes, Geochemistry, Fluids

Different Kinds of Stratigraphy Lithostratigraphy : composition, extent, classificatio Chronostratigraphy : dating & correlation Biostratigraphy : fossil content, assemblages Magnetostratigraphy : magnetic reversals & directions Stable Isotope Stratigraphy : 18/16O, 13/12C Sequence Stratigraphy : tectonics, eustasy, cycles

SEDIMENTS = CSI EARTH!