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FL Geology. The Rock Cycle. Igneous rocks . Form as magma cools and crystallizes Rocks formed inside Earth are called plutonic or intrusive rocks Scoria Obsidian Pumice Granite. Sedimentary rocks . Economic importance Coal Petroleum and natural gas Iron and aluminum Shale
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FL Geology Prepared by: Prof. Rodriguez
The Rock Cycle Prepared by: Prof. Rodriguez
Igneous rocks • Form as magma cools and crystallizes • Rocks formed inside Earth are called plutonic or intrusive rocks • Scoria • Obsidian • Pumice • Granite
Sedimentary rocks • Economic importance • Coal • Petroleum and natural gas • Iron and aluminum • Shale 5. Conglomerate
Metamorphic rocks • "Changed form" rocks • Produced from preexisting • Igneous rocks • Sedimentary rocks • Other metamorphic rocks
Metamorphic rocks • Metamorphic agents • Heat • Pressure (stress) • Chemically active fluids • Mainly water and other volatiles • Promote recrystallization by enhancing ion migration
Metamorphic rocks • Common metamorphic rocks • Slate • Gneiss • Marble • Parent rock is limestone
FL and Plate Tectonics • FL was once a part of NW Africa • This fragment formed the base for the carbonate buildup which includes the FL & Bahamas Platforms. • FL experienced cycles of sediment deposition & erosion throughout the Cenozoic Era (last 65 million years). Prepared by: Prof. Rodriguez
FL's Cenozoic-aged sediments include two major groups: the Paleogene & Neogene-Quaternary. • During the Paleogene, carbonate sediments formed due to biological activity of organism including foraminifera, bryozoan, mollusc, & coral. Prepared by: Prof. Rodriguez
Very little siliciclastic sediment ( sands, silts & clays) was able to reach FL because the "Gulf Trough" separated the FL Platform from the siliciclastic source area of the Appalachian Mountains. • In the late Paleogene, the Appalachians were uplifted, erosional rates increased, & siliciclastic sediments filled the Gulf Trough. Siliciclastic sediments then encroached upon the carbonate depositing environments. Prepared by: Prof. Rodriguez
Sediments deposited during the Neogene were primarily quartz sands, silts & clays with varying amounts of limestone, dolomite & shell. • In southern FL carbonate sediments still predominated because most of the siliciclastic sediments, moving south with the coastal currents, were funneled offshore. Prepared by: Prof. Rodriguez
The area of the modern-day Everglades was a shallow marine bank where calcareous sediments & bryozoan reefs accumulated. • These sediments compacted & eventually formed the limestone that floors the Everglades today. Prepared by: Prof. Rodriguez
Florida Limestone • Colonies of coral formed reefs in the shallow sea along the southern rim of the FL platform. • As sea levels fluctuated, the corals maintained footholds along the edge of the plateau; their reefs grew upward when sea level rose & retreated to lower depths when sea levels fell, accumulating 75 to 100 feet of limestone. Prepared by: Prof. Rodriguez
Sinkholes • The last drop in sea level exposed the ancient reefs which are the present FL Keys. Living coral reefs continue to grow in the shallow waters of the Keys. • Sinkholes are a common feature of FL's landscape. They are only one of many kinds of karst (chemical erosion) landforms, which include caves, disappearing streams, springs, & underground drainage systems, all of which occur in FL. Prepared by: Prof. Rodriguez
Limestone in FL are porous, allowing the acidic water to percolate through their strata, dissolving some limestone & carrying it away in solution. • Over eons of time, this persistent erosional process has created extensive underground voids & drainage systems in much of the carbonate rocks throughout the state. Prepared by: Prof. Rodriguez
Collapse of overlying sediments into the underground cavities produces sinkholes. Prepared by: Prof. Rodriguez
Winterpark Sinkhole Prepared by: Prof. Rodriguez
Florida Springs • When groundwater discharges from an underground drainage system, it is a , such as: • Wakulla Springs – south of Tallahassee • Silver Springs - Marion County • Fanning Springs - South of Gainesville • More than 700 springs in Florida Prepared by: Prof. Rodriguez
Ponce de Leon Spring, Volusia Prepared by: Prof. Rodriguez
Minerals of FL • Most common minerals includes: • 1. quartz (beach sand), • 2. aragonite (shells), • 3. calcite & • 4. clay minerals such as: • a. kaolinite (china clay) & • b. montmorillonite (Na). Prepared by: Prof. Rodriguez
Some minerals are of such economic importance that they are mined. • In NE FL, a group of minerals known as "heavy minerals" are mined from ancient beach ridges, useful for their titanium (Ti) content. Prepared by: Prof. Rodriguez
In southwest FL, phosphate minerals are mined for the manufacture of fertilizer products. • FL produces about 1/4 of the world's phosphate. Prepared by: Prof. Rodriguez
If limestone undergoes an intense amount of heat, it becomes the metamorphic rock, marble. • In FL, sedimentary rocks are the most common. Prepared by: Prof. Rodriguez
One example is shell fragments (the mineral ) that are cemented together by calcite to form the sedimentary rock coquina. Prepared by: Prof. Rodriguez
Limestone, is mined for road building & other construction applications. This rock is made up of small calcite particles formed by marine organisms that build up large reefs in the oceans. Prepared by: Prof. Rodriguez
Much of the surface of FL is covered by: • 1. sediment (loose mineral particles, such as quartz sands), or • 2. sedimentary rocks such as limestone & dolostone. Prepared by: Prof. Rodriguez
Igneous & metamorphic rocks do not occur naturally at the surface, • are found in deep wells reaching from 3,500 feet to deeper than 18,670 feet below land surface. Prepared by: Prof. Rodriguez
