GEO 102 Lecture 23 Outline of Last Lecture I. The beginning of the EarthOutline of Current Lecture II. Core Differentiation III. Water and OxygenIV. Tectonics, Weathering, Atmosphere, and ClimateV. Weathering Thermostat and Feedback Current LectureCore Differentiation- Early Earth was homogenized- Over time (as short as 30 million years) dense matter (Ni and Fe) sank to form core- Acted as an electro magnet and protected 2nd atmosphere from solar windo 1st atmosphere is lostWater- Came from comets but Earth used to be so hot that it could not exist in liquid form- First all vapor- Light could not penetrate- Cooled to condensation point- Rain filled basinsOxygen- Came much later. Mostly from photosynthesis and chemosynthesis- First oxygen from photochemical dissociationo Very small amount- ~2% of today- Larger quantities came from photosynthesiso Seen in BIF’s o Red bedso Initially from Prokaryotes Prokaryotes- life before seeds. Single cell organisms without a nucleusThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Tectonics, Weathering, Atmosphere, and Climate- Extensive continents by 3.6 Ga- Initial uplift led to weathering- Beginning of CO2 cycleo Weathering:o CaSiO3+CO2-----CaCO3+SiO2o Melting of marine critters at subductionso CaCO3+SiO2----CaSiO3+CO2CO2-Weathering Thermostat- Feedback is critical- Increased tectonic activity leads to new land and uplift- This leads to increased weathering- Increased weathering traps CO2 in resultant sedimentary rocks- Rocks are subducted and cycle resumesFeedback- Hot periods increase rains and water vapor (heating the Earth more)- Rains increase weathering- Ne sedimentary rocks trap CO2- Cools the Earth and lessens precipitation and weathering- Sedimentary rocks subducted and it
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