Geology 101 Week 5 Notes
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This 0 page Class Notes was uploaded by Delo Baker on Friday November 6, 2015. The Class Notes belongs to ESS 101 at a university taught by Swanson, Terry W in Fall 2015. Since its upload, it has received 52 views.
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Date Created: 11/06/15
Ess week 5 Oct 26 October 26th Discontinuous reaction 0 Early formed crystals from entirely new minerals through reaction with the melt Differentiate melt phase from solid phases 0 Fractional magma from Partial melting of rock 0 Fractional crystallization from a magma Magma or lava gt begins to crystalize Must separate solid phase 0 More dense o Darker o Femg from melting phase 0 silica is rst to melt o EXTRACREDIT Both overhead bulbs burned out on the projector October 28th 0 Formation of a volcano is controlled by the viscosity of the magma 0 Hawaiian shield volcano has high viscosity 0 Cone volcano has low viscosity and a high slope angle of strato Shield volcanos are composed of interlayer basalt flow 0 Formed through mantle hotspot o Quasistationary As the crust moves the hotspot moves forming new volcanos Allows us to track how fast the plate moves Ex Hawaiian Islands 0 As oceanic plate moves away from the hotspot the crust begins to cool increasing it density Crust subsides causing island to submerge Strato composite Volcano 0 Form along subduction zone 0 Subduction zone volcanism Has two phases 0 Initially magma underground begins to rise Large phencryst forms 0 Dissolved gas expands as magma rises 0 As gas expands gas pressure increases 0 When gas pressure exceeds the weight of the lava plug magma erupted explosively and pyroclasts fall near vent cinders 1st has explosive phase regassing o pyroclastic phase 2nOI lava eruption phase effusive phase 0 volcano rebuilds summit o Overtime magma becomes more silica rich through fractionation Pyroclastic cones 0 Form from erupted cinders 0 High gas content Comes from groundwater o Composed of fesic and ma c compositiions o o Pyroclastic cones my collapse to form maars October 30th Plateau basalts form where basalt flows erupt along linear rifts in terrestrial settings 0 le continental rift zone East African rift zone 0 Rigid crust will not stretch like an elastic band 0 Columnar structures 0 Trade off between concentric cooling ef ciency in packing Ground up or ground down 0 Ocean oor 0 Pillow basalts Form when basalt is erupted into water Palagonite Reddish orange clay formed from weathered basaltic glass 0 Volcanic landforms o Plutons lntrusive igneous rocks that crystalize from magma underground 0 Big minerals Granite Classi ed based on size and orientation relative to layered sedimentary rock in which they are intruded Subdivided based on size BIG landform or sub continental scale IE do you need aerial photography or distance fro pluton to see it in you entire eld of vision SMALL Outcrop scale 0 Can see entire pluton along side of rode lrregular country rock 0 Aligned with layered country rock Batholith gt 100kmquot2 within Expose to the surface through uplift and erosion of overlying country rock o Volcanc necks form when resistant magma is intruded into the vent Over time the less resistant rock is eroded away leaving resistant rock exposed in relief