1 10 2 https://theses.otagogeology.org.nz/files/original/88d22aead830fb492b5d58c32571d794.pdf 3485554f000f218ae65b5295b48b480c 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 Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Author last name Last name of the Author Ross Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student White, J.D.L. Abstract The Abstract for this thesis The Jurassic Ferrar large igneous province of Antarctica contains significant mafic volcaniclastic deposits, underlying the Kirkpatrick flood basalts. In South Victoria Land, the mafic volcaniclastics are referred to as the Mawson Formation. At Coombs Hills, the Mawson is interpreted as filling a large vent complex, which was re-examined in detail to better understand vent-forming processes. Two contrasting types of cross-cutting volcaniclastic bodies were found in the complex, both of which are interpreted to have been forcefully emplaced from below into existing, non-consolidated debris. The first type consists of country rock-rich lapilli-tuff pipes. These are interpreted as fossilized remnants of subterranean debris jets which originated when phreatomagmatic explosions occurred near the walls or floor of the vent complex, causing fragmentation of both magma and country rock. The second type of cross-cutting body consists of basalt-rich tuff-breccias and lapilli-tuffs, some of which could have been generated by explosions taking place within pre-existing basalt-bearing debris, well away from the vent walls. Other basalt-rich zones, accompanied by domains of in situ peperite and coherent basalt, are inferred to have originated by less violent processes. At nearby Allan Hills, the Mawson can be divided into two informal members, m1 and m2. Member m1 is exposed only at central Allan Hills, consists essentially of sedimentary material from the underlying Beacon Supergroup, and is interpreted as a ::::;180 m-thick debris avalanche deposit. Most megablocks in m1 were derived from the late Triassic Lashly Formation, parts of which were probably only weakly consolidated in the Jurassic. Sandstone breccias dominate volumetrically over megablocks within the deposits. This indicates pervasive and relatively uniform fragmentation of the moving mass, and probably reflects the weak and relatively homogeneous nature of the material involved. The avalanche flowed into a pre-existing topographic depression carved into the Beacon sequence, and flow indicators reveal a northeastward movement. Sparse globular basaltic megablocks suggest that Ferrar intrusions played a role in triggering the avalanche. Member m2, which is exposed at both central and southern Allan Hills, consists predominantly of metre-thick basaltic volcaniclastic layers that fall into three broad categories: (1) poorly sorted, coarse lapilli-tuff and tuff-breccia; (2) block-rich layers; (3) tuff and fine lapilli-tuff. The former type is interpreted as the deposits of high-concentration pyroclastic density currents (PDCs), probably formed during the collapse of phreatomagmatic eruption plumes. Occasional block-rich layers probably were formed by both ballistic fall from local vents and pyroclastic flows, and the finer-grained layers were probably deposited by dilute PDCs. Dilute, moist turbulent currents were also likely responsible for the generation and deposition of large (::::;4.5 cm) rim-type accretionary lapilli. The thick layers are locally underlain by or interbedded with thin tuff ring-style volcaniclastic layers, and all the layers are underlain and invaded by basalt-rich tuff-breccias and lapilli-tuffs. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Coombs Antarctica Allan Hills Antarctica Victoria Land south Thesis description Number of pages, maps, CDs, etc. 1 v. (various pagings) : ill., maps ; 30 cm. 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/. Identifier An unambiguous reference to the resource within a given context 2005Ross Creator An entity primarily responsible for making the resource Ross, Pierre-Simon. Date A point or period of time associated with an event in the lifecycle of the resource 2005 Title A name given to the resource Volcanology of the Mawson Formation at Coombs and Allan Hills, South Victoria Land, Antarctica Subject The topic of the resource Volcanology lapilli - tuffs mafic volcaniclastics Mawson Formation vent-forming processes https://theses.otagogeology.org.nz/files/original/351ab276dfbc8ca6a1c2fe58142ec89b.pdf dbfa30d421ca1446a3f50a1cc19239cf 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 Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Location WKT (WGS84) The location stored in WKT (WGS84) format POLYGON ((159.611075921071176 -76.748316544760868,159.59503935563319 -76.748039960184116,159.5989590931257 -76.734569862430405,159.598978675760151 -76.734502503862643,159.599180922358386 -76.733806741550183,159.602306898959512 -76.72304378433752,159.604374234965746 -76.715916320645661,159.609728851011255 -76.715990491823646,159.669333135702288 -76.716808468619035,159.708671534839027 -76.71734063605183,159.765043185662762 -76.718092571315296,159.763183171099996 -76.725772770284109,159.761360840412294 -76.733288879283279,159.757407528486851 -76.749565288902389,159.75729266893876 -76.750037588018429,159.757110070628499 -76.750788373720212,159.713379693940311 -76.75005702850801,159.665119859742646 -76.74924115017167,159.611075921071176 -76.748316544760868)) Author last name Last name of the Author Lockett Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Abstract The Abstract for this thesis In the Allan Hills, Victoria Land, Antarctica, Beacon Supergroup sedimentary rocks are juxtaposed with volcaniclastic rocks of the Ferrar-age Mawson Formation. The Mawson Formation and its correlatives along the Transantarctic Mountains contain an abundance of rather chaotic rocks consisting of once-glassy, juvenile basaltic grains mixed with broken country rock from the Beacon. Many of these rocks, including those at Allan Hills, have been interpreted in terms of a large vent complex that formed in advance of Kirkpatrick flood-basalt eruptions of the Ferrar large igneous province. New Watters peak, the Mawson Formation at Allan Hills can be divided into two units. One unit ("Mawson A") contains little or no juvenile basaltic material. Mawson B is more typical Mawson Formation tuff breccia, containing a variably high concentration of glassy juvenile material; it forms most of the Allan Hills and much of the nearby Coombs Hills. Mawson B is interpreted to be a intra-vent deposit, within a large shallow vent complex. Mawson A has a sharp to gradational contacts with unit B, and a gradational contact with Beacon Supergroup country rock. There are two main facies within Mawson A. The lower facies (Mawson Al) consists entirely of blocks of medium grained sandstone. Nearest the contact, blocks are of decimeter scale, rotated only slightly or not all, and beds within blocks can be traced from block to block for metres. Thin seams of sand matrix separate the blocks, and the sand consists of the same grains as the sand constituting the sandstone in the blocks. Further from the contact, blocks are commonly rotated and squeezed back together with little or no matrix between them. This unit is interpreted to have formed at the vent margin due to marginal subsidence caused by the removal of fragmented rock from the site of phreatomagmatic eruptions. A second facies (Mawson A2) lies further from the contact with the Beacon Supergroup, is more chaotic in appearance, and comprises predominately medium grained sandstone, but also contains clasts of coarse-medium sand pebbly congmplerate, fine grained sandstone, coal and glassy juvenile material. Clasts are randomly orientated and no internal structures are visible. This unit is interpreted to a debris flow Analysis on coal within this unit suggests that it was sourced from high in the Lashly Formation. The flow travelled into the vent complex implying it had negative relief. The flow was most likely the result of continued volcanic/tectonic seismicity causing failure along incipient weaknesses in the country rock surrounding the vent. After the flow volcanic activity continued and new intra-vent Mawson B was formed which incorporated some of the debris of the flow. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Antarctica Victoria Land south Allan Hills Thesis description Number of pages, maps, CDs, etc. viii, 105 leaves : ill. (some col.), maps (some col., 1 folded) ; 30 cm. 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/. Identifier An unambiguous reference to the resource within a given context 2003Lockett Creator An entity primarily responsible for making the resource Lockett, Gillian M. (Gillian Mary) Date A point or period of time associated with an event in the lifecycle of the resource 2003 Title A name given to the resource Landslide and debris flow deposits at the margin of a large vent complex, Mawson Formation, Allan Hills, southern Victoria Land, Antarctica Subject The topic of the resource Geomorphology debris flow deposits landslide Mawson Formation rock debris slopes vent complex