1. Sedimentary Geology Geos 240 – Chapter 3-2 Sedimentary Petrology-2
Dr. Tark Hamilton
Camosun College

2. QFL + Grain Size Prism
QFL triangle + Grain Size Prism: Sandstones, Wackes, Mudstones: silts, shales, argillites
Wackes are rocks with floating sandy sized grains in a silty to clayey matrix, essentially a sandy mud.
Feldspathic rocks derive from granitic/plutonic terranes. Lithic rocks from volcanic and sedimentary terranes.
Notice how restricted and rare Quartz wackes and Quartz arenites are. These require ancient sedimentary terranes or very long systems.

3. Provenance Q F L
Due to the mechanical and chemical resistance of quartz, it is the end of the line is coarse sediment evolution, irrespective of the original hinterland/terrane. Fe-oxy-hydroxides and kaolinite are also sedimentary survivors.

4. Metamorphic and sedimentary terranes can also yield lithic fragments to sediments but active volcanoes shed lots of debris and spawn whole volcaniclastic successions.. Amygdaloidal basalt as vesicles are infilled by secondary minerals. Fine grained volcanic rocks are hard to classify correctly as they do not show much of their compositional clues but habit, phenocrysts, vesicularity and colour. Tuff means airfall (massive in several pulses) or waterlain (reworked, bedded) a better generic word is pyroclastic for monogenetic ones and agglomerate for polymictic clasts in a muddy matrix. The latter might result from an explosion breccia, a landslide or a lahar. It is better to have a correct but imprecise term than a precise but wrong term!

5. A. Feldspar (plagioclase) phyric volcanic (VRF) showing trachytic texture with crude flow alignment of feldspar crystals., B. Welded tuff Fragment with flattened and partially devitrified glass shards, C. Regional metamorphic rock fragment (Foliated + Qtz & Micas) from shear or other deformation, D. More mature, second cycle sediment with Chert (Left) and fine grained sandstone/siltstone fragment (R)

6. 2nd (or later) cycle quartz grain with silica cement rim
Euhedral/Embayed volcanic quartz little transported (close to source)
Like A but with about 45% porosity impregnated with blue epoxy. I wish I had patented this technique when I invented it back in Now everybody does it!
Polycrystalline quartz grain with sutured boundaries, strained/recrystallized & birds-eye muscovite grains. Metamorphic and plutonic quartz often shows undulose extinction from strain. Metamorphic quartz like in rock D often has triple point or sutured boundaries from advanced pressure solution. Rocks A & C are compositionally mature and mechanically mature due to the abundance of well sorted quartz sand grains.

7. Even more eroded now from storms and even tourism
Even more eroded now from storms and even tourism! Permian desert red-beds are the source of the quartz and hematite from the Pangea supercontinent prior to Nova Scotia & PEI rifting away from North Africa. So is this why Anne of Green Gables had Red Hair?

8. Dolostone Breccia Sandstone
Rocks that are red, orange or purple contained oxidized and subaerially weathered iron minerals. They tend to be good for paleomagnetism. These oxidized purplish beds formed on intermittently exposed tidal flats near a sand source and river delta but reworked along a tropical shoreline, thus the dolostones. (Dolomite is a mineral CaMg(CO3)2 while Dolostone is a rock with predominant dolomite.(Usually this is transformed from primary limestone by evaporation involving Mg+2 bearing fluids like seawater or basinal brines) Sandstones here weather blocky and in positive relief. The interbedded dolomites here weather rubbly and recessive due to their conglomeratic texture and easier chemical weathering.
Sandstone

9. Crudely laminated quartzose siltstone to very fine sandstone with some feldspar grains and subordinate silty matrix. The sand silt cutoff is 63 microns (0.063 mm). The layering shows that the depositional process varied in energy and or was intermittent.

10. Provenance from Clasts & Accessory Minerals
Conglomerates & coarse grained lithic sands afford provenance & tectonic setting to be interpreted from lithic clasts: granitic, regional metamorphics, volcanics, second cycle sediments…
Even fine sands and silts contain rare accessory minerals which are heavy, hard & chemically resistant like: zircon, baddeleyite, monazite, apatite, garnet, tourmaline, hornblende, epidote, topaz, corundum, ilmenite, native gold. These are concentrated using heavy liquids, panning or centrifugation. Zircons can even be dated. Mapping of past drainages has been accomplished for many units in the Phanerozoic section of Western Canada because of unique assemblages from each upstream shield terrane. Zirconium and titanium could be economically recovered from tar sands tailings.
Source regions (former hinterland mountain belts adjacent to a basin) contain unique rock types, mineral assemblages and ages of minerals. Because rivers all have unique watersheds, the provenance of minerals and rock fragments varies accordingly. Even glaciers scraping over the Canadian Shield abrade and include what they cross so that till mapping of heavy minerals can be used to find diamond and other mineral deposits up-ice. In the case of diamonds: the heavy mineral suite is Pyrope Garnet, Chromian Diopside and Ilmenite as accessories from the peridotite inclusions in the kimberlite pipes. Some clastic materials like carbonates or glass are soft and readily react with acidic surface waters such that they seldom make it into the rock record. When they do, you know they just fell off of a nearby volcano or a steep fault scarp in an arid or active tectonic region.

11. Were there no other life or fossils, carbonate rocks alone attest to life in water on planet earth. This is due to the bacterial metabolism of organics from methane to carbohydrates and the waste products of oxidized carbon as carbon dioxide gas and dissolved carbonic acid and its ions. These processes leave textural evidence as framboids, strings, films etc. and fractionate both carbon and oxygen isotopes saying “life was here”.
Bio-&
Deep sea micro- & nannofossil ooze & cold carbonate vent mounds *Diagenetic carbonate cements from sub- & anaerobic bacterial processes

12. The Biochemistry of Carbonates
Photo/chemosynthesis life makes hydrocarbons or carbohydrates
atmospheric carbon dioxide and water
in the presence of energy (sunlight, chemical bonds)
And enzymes or mineral substrates to catalyze reactions
Prokaryotes: Archea, Eubacteria or Eukaryotes, Plant life
6CO2 (g) + 6H2O (l)  C6 H12O6 (aq) or cellulose
Some Archea (methanogens), since 4 Ga, don’t require oxygen
CO2 (g) + 2H2 (g)  CH4 (g) or
Aerobic or anaerobic metabolism of organic molecules (food/fuel source) regenerates carbon dioxide with or without free oxygen:
CH2O (aq) + O2 (g) H2CO3 (aq)  HCO3 –(aq) + H+(aq) aerobic
CH4 (aq)+ SO4‑2(aq) => S‑2(aq) + H+(aq) + HCO3‑(aq) + H2O(l) anoxic
Add dissolved Ca+2 and Fe+2 to make Calcite and Pyrite
Inorganic carbonate precipitation happens in evaporties and hydrothermal settings but even there closer examination usually seems to involve archaea
See this website of C. Mallery of Miami Univ. to review nomenclature, structure and environments for prokaryotes and eukaryotes.
Most of the biomass on the planet > 80% is as these unicellular things, in the sea and other waters whether pores in soil, rock or in your own body!
For the anoxic reactions the energetic Carbon-carbon and carbon hydrogen bonds can be oxidized but only if there is some oxidized ion around like sulfate, nitrate, ferrate, uranyl etc. wherein there is an atom capable of accepting extra electrons. This happens in pore spaces below the seafloor or lakebed or below the water table in sedimentary basins and is ultimately responsible for much cementation and diagenetic mineral deposits. Geologists are gradually realizing the importance of these processes and biogeochemical mechanisms.

13. Limestone Components Foraminifera Micrite Sparry Cemented Calcarenite
Rounded biogenic sand sized calcite or aragonite grains in beachrock C are cemented by radial pore lining needles of sparry calcite cement. What does this kind of cementation do to the porosity and the permeability of the sediment?

14. Carbonate allochem grains:
A) ooliths nucleated on prior grains (shell fragments, detrital silicate minerals) originally thought to form on shallow offshore bars or banks, many are also found on back beach dunes and may have originated in a terrestrial setting. On sediment starved shelves, ooliths can be glauconite (green/brown) concentric.
B) Pellets (fecal pellets) either of pelagic or benthic organisms, usually oval shaped and turbid to opaque. Often replaced partially or completely by phosphates or iron oxides and silicates.
C) Grapestone clusters from shapes. Often formed by sub-oxic bacterial colonies transforming sedimented organics to carbonates in warm saline waters.
D) Curved and crenulated cross sections of brachiopod shells. Round, disc shaped crinoid ossicles (column fragments). The internal texture is of many small highly birefringent calcite or aragonite grains that appear “salmon pink” and seem to twinkle and show interference crosses upon rotation. These column fragments are far more common than the hold fast or calyx (head) used to classify species. This is no an encrinal limestone with sparry interstitial carbonate cement.

15. The “Godfather” of Carbonate Geology
Robert Lewis (Luigi) Folk San Salvador, Bahamas
June 2008
Age ~73 (Upper Holocene)
(The logo on the dirty ball cap is an ad for a local backhoe company
in Austin Texas)
Robert Lewis (Luigi) Folk, San Salvador, Bahamas, June 2008
The logo on the dirty ball cap is an ad for a local backhoe company in Austin Tx

16. LR Mud Silty Mud Sandy Mud Muddy Silt/Sand Breccia/ Conglomerate
Field
See SEPM website for both classifications:
Dunham 1962 and Embry & Klovan 1971 focus on rock textures and the role of matrix mud versus framework grains. This is most suited for field descriptions of outcrop weathering textures and hand specimens using a hand lens (or binocular microscope in the lab). By contrast Folk 1959, 1962 focused on the proportion of grains to matrix and the descriptive character of the grains. This is most suitable for petrography (thin section description). Consequently most carbonate geologists use both schemes (Kendall, 2005) describing for instance a wackestone in their field notes and a sparsely packed bio-pel-micrite from more detailed description of thin sections.
Lab