Searching for the source of the Footprint Tuff (Laetoli, Tanzania): a petrological and indicator-mineral perspective

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dc.contributor.authorGao, Song
dc.contributor.examiningcommitteeHalden, Norman (Geological Sciences)en_US
dc.contributor.examiningcommitteeZaitsev, Anatoly (St. Petersburg State University)en_US
dc.contributor.supervisorChakhmouradian, Anton (Geological Sciences)en_US
dc.date.accessioned2019-09-13T19:15:44Z
dc.date.available2019-09-13T19:15:44Z
dc.date.issued2019-08en_US
dc.date.submitted2019-08-30T00:12:57Zen
dc.degree.disciplineGeological Sciencesen_US
dc.degree.levelMaster of Science (M.Sc.)en_US
dc.description.abstractThe East African Rift System represents the world's quintessential example of an active intracontinental rift system. Within the Rift, a complexly stratified 152-m thick tuff sequence at Laetoli (northern Tanzania) is a well-preserved paleoanthropological site. This sequence comprises fossil- and artifact-rich aeolian, water-infiltrated and air-fall tuff beds, the best-known of which is the so-called Footprint Tuff, which hosts the earliest record of hominin bipedalism. This stratified carbonate-rich air-fall tuff unit is located approximately 30 km southwest of the Sadiman volcano. It has been a matter of debate for years whether the Sadiman volcanism could be the source of the Footprint Tuff. Based on the petrographic, mineralogical, geochemical and geochronological data obtained in the present work, volcanic activity at Sadiman can no longer be ruled out as one of the sources of the Laetolil tuffs because indicator minerals from these two localities (including melilite, garnet, perovskite, titanite and apatite) share many compositional similarities in the distribution and abundance of trace elements. The Sr-Nd isotopic characteristics of nephelinites from Sadiman suggest that their parental magmas originated by partial melting of a sub-continental lithospheric mantle source affected by plume activity. An Ar-Ar phlogopite age of 4.3 ± 0.1 Ma, obtained in the present work, provides further constraints on the timing of this magmatism. The possible evolutionary paths of parental magmas were reconstructed for the first time on the basis of petrographic observations and trace-element fractionation models.en_US
dc.description.noteOctober 2019en_US
dc.identifier.urihttp://hdl.handle.net/1993/34262
dc.language.isoengen_US
dc.rightsopen accessen_US
dc.subjectFootprint Tuffen_US
dc.subjectIndicator-mineralen_US
dc.subjectGeochemistryen_US
dc.subjectMineralogyen_US
dc.subjectSadiman volcanoen_US
dc.subjectPetrologyen_US
dc.subjectGeochronologyen_US
dc.subjectTrace elementen_US
dc.titleSearching for the source of the Footprint Tuff (Laetoli, Tanzania): a petrological and indicator-mineral perspectiveen_US
dc.typemaster thesisen_US
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