https://bereket-haileab.geology.sites.carleton.edu/files/original/480400d70e14e19b263e1ac2f5aeb483.jpg 04eee0da2cf809dced3558e7dce65ce9 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Igneous Rocks Subject The topic of the resource This collection covers both volcanic and intrusive rocks, including rhyolites, granites, diorites, andesites, basalts, gabbros, diabases, pumices, obsidians, syenites, phonolites, peridotites, carbonatites, dacites, trachyte, dunites, xenoliths, ignimbrites, and pegmatites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Thin section and hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-184 Subject The topic of the resource Trachyte Description An account of the resource Major Minerals: nepheline, clinopyroxene, sodic pyroxene, sanidine, orthoclase<br />Minor Mineral: chlorite<br /><br /> <p>Olduvai Gorge (Tanzania) lies within the East African Rift System, a tectonically active zone characterized by widespread volcanic activity. The volcanic rocks in this area range from basaltic to more evolved intermediate to alkaline compositions, including trachytes and phonolites associated with late-stage rift volcanism.</p> <p>The mineralogy of BH250-184 is dominated by alkali feldspar (sanidine or orthoclase), nepheline, and sodic pyroxene. The texture is typically aphanitic to porphyritic, with feldspar phenocrysts set in a fine-grained groundmass, displaying a trachytic texture.</p> <p>The chemistry of BH250-184 includes (see the table):</p> <p>Moderate to high SiO₂ content (~60–65 wt%)</p> <p>High alkali content (Na₂O + K₂O typically 7–9 wt%)</p> <p>Low to moderate MgO and FeO</p> <p>Enrichment in incompatible elements such as Rb, Ba, and Sr</p> <p>These characteristics are typical of potassic to ultrapotassic compositions commonly found in rift-related alkaline magmatism.</p> <p>Olduvai Gorge, located in northern Tanzania within the East African Rift Valley, is one of the most important paleoanthropological sites globally and is often called the "Cradle of Mankind." Fossil deposits here span from about 2 million to 15,000 years ago, covering crucial periods of human evolution. Key early hominid fossils discovered at Olduvai include Homo habilis, considered one of the first members of the genus Homo and associated with early tool use; Paranthropus boisei, a robust australopithecine species adapted to heavy chewing with strong jaws and large teeth; and Homo erectus, linked to more advanced tools and possibly the early use of fire. The site is also famous for the Oldowan tool industry—some of the earliest known stone tools dating back around 2.6 million years—which includes simple flakes and choppers that reflect early technological innovation. Additionally, volcanic ash layers (tuffs) found at Olduvai provide precise dating of fossils, while sediment records preserve evidence of ancient landscapes, climates, and fauna, offering valuable insight into the environments inhabited by early hominids.</p> <br /><br /><iframe width="1800" height="100" src="https://docs.google.com/spreadsheets/d/e/2PACX-1vS4nyqCmZQGn3t6vX4g4nhDPwHMBaKrigt1LaY2pykWbBGXB1wNb6FYArx625I-JTtD7lyg4uz1OS1r/pubhtml?gid=528629333&amp;single=true&amp;widget=true&amp;headers=false"></iframe> Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Location: Olduvia Gorge, Tanzania Nearby Geographic Feature: Olduvai Gorge GPS Coordinates: 2°59'31.72"S, 35°21'7.81"E Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample 184. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Hand sample and thin section Relation A related resource <iframe width="100%" height="600" style="border: 0;" src="https://carleton.maps.arcgis.com/apps/instant/media/index.html?appid=ffeb374234674fb2899e3b5d4bf3b0fd" frameborder="0" allowfullscreen="allowfullscreen">iFrames are not supported on this page.</iframe><br />View on ArcGIS Online <a href="https://carleton.maps.arcgis.com/home/item.html?id=ffeb374234674fb2899e3b5d4bf3b0fd">here</a><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1xTZPbURZuxaaekVyNZSAJ9yo3s-OABCa/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1AkQvrKnKQ3YXIuQyQG0xO2p0OX3oLe6B/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1JvLeL2V0HZH_o1aMOpKGCY-yJ1BT1NU8/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1-eDTh9Rp5BaPvOz8jLncZt6CLTSxHHsR/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1nNE_eyfKeZ8z_B_eDhfJRj9pw30J7oh6/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1pmnADErAWxIGZq_vJatKEcqYHMIFPxBJ/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/19idVHKCsjm4kAhlJ-24SnrRDPCazGUpm/preview" allow="autoplay"></iframe><br />TAS diagram of sample BH250-184. Creator An entity primarily responsible for making the resource Bereket Haileab alkaline volcanic rock East African Rift System felsic igneous Nepheline Olduvai Gorge Paleoanthropology Context phonolite plutonic Potassic to Ultrapotassic Sodic pyroxene Tanzania trachyte Trachytic Texture Volcanic Geochemistry