2 3 2014 San Juan River UT Sediments and Sedimentary Rocks Solidified Weathering Products San Juan River UT Size Sorting Particle Sizes The different minerals that form as weathering products have different characteristic grain sizes Un weathered material has largest grain size Quartz sand is 0 1 to 2 mm Clays are less than 0 001 mm 1 m Ca 2 Na 1 CO3 2 SO4 2 and Cl are dissolved 1 2 3 2014 Size Sorting Gives Different Sedimentary Rocks Depositional Environments Breccias have moved very little Conglomerates are near source continental Sandstones are continental Eolian sandstones are desert deposits Fluvial sandstones are river deposits Shales are shallow marine salt water Limestones are tropical shallow marine reefs Evaporites result from evaporation of seawater Breccias Conglomerates Sandstones Shales Limestones tropical 2 2 3 2014 Granite Weathering Quartz Sand Feldspar Clay Mica Clay Conglomerates and Breccias Breccias are composed of coarse angular fragments Breccia fragments have not traveled far Conglomerates are composed of coarse rounded fragments Conglomerate fragments have traveled further Conglomerates and Breccias are typical of continental alluvial fans Conglomerate Breccia Breccias Conglomerates Breccias Conglomerates Sandstones Arkose contains feldspar and is near source Fountain Formation Flatirons is made of arkose and conglomerates Eolian sandstones are desert wind deposits Commonly show cross bedding Fluvial sandstones are stream deposits Commonly have asymmetric ripples and channels 3 2 3 2014 Eolian Sandstone Cross bedding Eolian Sandstone Cross bedding Eolian Sand Dunes Sandstone Micrograph Quartz grains Asymmetric ripples looking upstream Ripplemarks Fluvial River Sandstone 4 2 3 2014 Organic Sediments Sandstones Swamp and bog deposits rich in organic matter lithify to form coal Peat is the first stage Lignite is peat that has begun to lithify Bituminous coal is an abundant energy source Anthracite is metamorphosed coal Petroleum and natural gas are also derived from organic sediments Organic Sediments Organic Sediments This carbon is taken from the Shales and Mudstones atmosphere as CO2 and reduced by photosynthesis to carbon and hydrocarbons plus oxygen The oxygen goes to the atmosphere The reduced carbon is buried When the carbon is burned the CO2 goes to atmosphere The energy comes from where Shales and Mudstones Clay and silt can only be deposited in standing water Clays are layer silicates like mica and grains align so layers are parallel Shale breaks along the layers and is said to be fissile Mudstones and siltstones are massive don t break along layers 5 2 3 2014 Mudcracks The most abundant mineral in shale is clay Shale breaks along the layers and is said to be fissile Shales were deposited in standing water Shales Limestone Limestone is made of calcite CaCO3 Most Phanerozoic limestones are biogenic formed by critters Seawater is saturated in calcium carbonate Calcite is more soluble in cold water than warm Limestone is tropical marine Dolomite is calcium magnesium carbonate CaMg CO3 2 Most limestone is biogenic Most limestone is biogenic 6 2 3 2014 Most limestone is biogenic Limestone calcite is soluble in water Caverns form in limestone Caverns form in limestone Limestones tropical Dolomite and Limestone Outcrop Dolomites Italy Calcium Carbonate Saturation in Little Colorado River 7 2 3 2014 Calcium Carbonate is saturated in warm seawater Evaporites Solution mining of sylvite KCl at Potash UT Size Sorting Gives Different Sedimentary Rocks Evaporites Evaporites are rocks deposited from evaporating seawater As seawater evaporates the sequence of minerals deposited is 1 2 3 4 calcite CaCO3 gypsum CaSO4 2H2O halite salt NaCl sylvite KCl San Juan River UT coastal sediment sequence Limestone shale sandstone Depositional Environments Conglomerates are near source continental Sandstones are continental Eolian sandstones are desert deposits Fluvial sandstones are river deposits Shales are shallow marine salt water Limestones are also shallow marine Evaporites result from evaporation of seawater 8 2 3 2014 Sedimentary Terms Boulder 256mm Cobble 64 256mm Pebble 2 64mm Sand 06 2 mm Silt 4 60 m Clay 4 m Conglomerate Breccia Arkose Sandstone Siltstone Shale Limestone Evaporite Reef Lithification Cross bedding Ripple marks Alluvial Fluvial Eolian Sedimentary Short Essays Short Essays 6 How do the weathering rates of the different minerals in granite give rise to different grain sizes of the weathering products 7 How does the transport of sediments weathering products by wind and water result in the different sedimentary rocks having different compositions 1 What is a mineral and how does it differ from a rock 2 What are protons neutrons electrons isotopes and elements and how are they formed 3 What is igneous fractionation and how does it account for the differences between mantle oceanic crust and continental crust Short Essays Clicker Question 4 What is the scientific method and how is it used to draw conclusions about the origin and age of the Earth 5 What are the two major energy sources that drive Earth processes and which processes does each primarily control What is the most likely geologic setting in which limestone was deposited A Continental alluvial fans B Continental deserts and beaches C Shallow water marine D Deep water marine E Reefs Tropical Shallow Marine 9 2 3 2014 Clicker Question What is the most likely geologic setting in which limestone was deposited A Continental alluvial fans B Continental deserts and beaches C Shallow water marine D Deep water marine E Reefs Tropical Shallow Marine Clicker Question What is the most likely geologic setting in which conglomerate was deposited A Continental alluvial fans B Continental deserts and beaches C Shallow water marine D Deep water marine E Reefs Clicker Question The most abundant mineral in sandstone is A Quartz SiO2 B Clay C Calcite CaCO3 D Gypsum E Halite salt Clicker Question What is the most likely geologic setting in which conglomerate was deposited A Continental alluvial fans B Continental deserts and beaches C Shallow water marine D Deep water marine E Reefs Clicker Question The most abundant mineral in sandstone is A Quartz SiO2 B Clay C Calcite CaCO3 D Gypsum E Halite salt Clicker Question The most abundant mineral in limestone is A Quartz SiO2 B Clay C Calcite CaCO3 D Gypsum E Halite salt 10 2 3 2014 Clicker Question What is the most likely geologic setting in which sandstone was
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