![]() ![]() Yoon, head of the department of architecture, worked with a team of faculty, staff, and students, and international experts, including MIT Professor John Ochsendorf, a structural engineer and expert of masonry vaulting structures. The memorial represents the community coming together where strength comes from unity,” says architect J. “Each stone is necessary to transfer loads and create equilibrium. Watch the dedication webcast or view a video on the creation of the memorial titled Strength Through Unity: the Making of the Collier Memorial at MIT. Collier, who was killed during the Boston Marathon bombing aftermath on April 18, 2013, is represented by an exceptional symbol of community-32 granite pieces that depend upon each other for strength and balance. The MIT community gathered April 29 to dedicate the Officer Sean Collier Memorial, a star-shaped granite structure that symbolizes the flavor of his life and his sacrifice. The heat source is the basaltic magma the heat required for partial melting of the roof is supplied largely by heats of crystallization of phases that settle out of the liquid - mostly olivine, clinopyroxene and plagioclase.The Collier Memorial was dedicated April 29, 2015, to honor fallen MIT police officer Sean Collier. Intermediate liquids include MgO-depleted and Na 2O-enriched gabbro, which precipitated anorthosite, and alkali diorite. This reaction of magma and roof involves both partial melting and the reconstitution and precipitation of refractory phases, as Bowen proposed. The syenitic liquid in turn reacts with granodioritic to granitic intermediate crust of amphibolite facies to produce the predominant fayalite-free biotite and biotite-hornblende granites of the batholith. A suite that includes gabbro or basalt, anorthosite, quartz syenite, fayalite granite, riebeckite granite, and biotite and/or hornblende granites is of worldwide occurrence.Ī model is proposed in which mantle-derived, convecting alkali olivine basaltic magma first reacts with K 2O-poor lower crust of granulite facies to produce magma of quartz syenitic composition. The Pikes Peak intrusives are similar in mode of emplacement, composition, and probably genesis to rapakivi intrusives of Finland, the Younger Granites of Nigeria, Cape Ann Granite and Beverly Syenite, Mass., and syenite of Kungnat, Greenland, among others - allowing for different levels of erosion. ![]() ![]() Average Na 2O percentages in quartz syenite are 6.2, fayalite granite 4.2, and fayalite-free granite 3.3 MgO contents are low, 0.03–0.4% FeO averages 1.9–2.5%. Nearby fayalite-free biotite granite crystallized at higher water fugacity.Īll types of syenite and granite contain 5–6% K 2O through a range of SiO 2 of 63–76%. Biotite and fayalite compositions and the ‘granite minimum’ imply completion of crystallization at about 700☌ and 1,500 bars. In the south ilmenite and manganian fayalite indicate f O2 of 10 −17 or 10 −18 bars. Feldspar assemblages indicate late stages of crystallization at about 720☌. Aplite residual to fayalite-free biotite granite in the north formed at about 1,500 bars, or 5 km depth. Biotite granite and biotite-hornblende granite are predominant quartz syenite, fayalite granite and riebeckite granite are present in minor amounts.įayalite-bearing and fayalite-free quartz syenite, fayalite-biotite granite and riebeckite granite show a well-defined sodic differentiation trend the less sodic fayalite-free granites exhibit a broader compositional range and no sharp trends.Ĭrystallization was largely at P H2O < P total P H2O approached P total only at late stages. ![]() ago, sharply transects its walls and may have breached its roof. It was emplaced at shallow depth 1,040 m. The batholith is elongate in plan, 50 by 100 km, composite, and generally subalkalic. This study of the Pikes Peak batholith includes the mineralogy and petrology of quartz syenite at West Creek and of fayalite-bearing and fayalite-free biotite granite near Mount Rosa major element chemistry of the batholith comparisons with similar postorogenic, intracratonic, sodic to potassic intrusives and genesis of the batholith. ![]()
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