Reading Epsl 2006.Pdf
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Evolution of Granulites from Macrobertson Land, East Antarctica
t^Õ{-qt Evolution of granulites from MacRobertson Land, East Antarctica by Ian Scrimgeour Thesis submitted for the degree of Doctor of Philosophy in The University of Adelaide (Faculty of Science) April, 1994 ií-ì .,\. .1 .i fi i, '¿' ¡ ¡i\ \ rl Abstract and Granulite facies rocks in the northern Prince charles N{ountains an extensive Mid surrounding regions of MacRobertson Land form part of of the proterozoic (1000 Ma) regional granulite facies terrain which dominates much granulite terrains in the coast of East Antarctica. As one of the largest exposed processes which result in world, it provides an excellent opportunity to examine the of granulite formation, yet much of the metamorphic and Structural evolution to areas to the MacRobertson Land has remained relatively unknown in comparison east and west. rocks on Jetty In the northeastern Prince Charles l\{ountlins granulite flcies and post-tectonic Peninsula consist of a supracrustal sequence intruded by syn- andT -7 granites, and preserve evidence for peak metamorphism (Ml) at -800oc '5 were kbars. In metapelitic rocks, M1 garnet- and sillimanite-bearing assemblages and symplectites which overprinted by the development of cordierite-bearing coronas dipping thrusts formed during the development of tight upright fol<ls and steeply cordierite- (Dz). cordierite-spinel symplectites between gíìfnet and sillimanite and of 1 - 2 orthopyroxene symplectites between garnet and biotite imply decompression assemblages kbars following M1. However, the stabilisarion of biotite-sillimanite were separated by a between the M1 and syn-D2 assemblages suggests that they Fine period of cooling, and that decompression was therefore not near-isothermal' 80 km to the grained reaction textures in pelites from Trost Rocks, a remote outclop A Sm-Nd north on an island in the Amery Ice Shelf, plesorve a similar history. -
Early Diagenetic Siderite in the Panorama Point Beds (Radok Conglomerate, Early to Middle Permian), Prince Charles Mountains, East Antarctica
vol. 31, no. 2, pp. 169–194, 2010 doi: 10.4202/ppres.2010.10 Early diagenetic siderite in the Panorama Point Beds (Radok Conglomerate, Early to Middle Permian), Prince Charles Mountains, East Antarctica Krzysztof P. KRAJEWSKI 1,3*, Nikolai A. GONZHUROV 2, Anatoly A. LAIBA2 and Andrzej TATUR3 1 Instytut Nauk Geologicznych PAN, Twarda 51/55, 00−818 Warszawa, Poland <[email protected]> *corresponding author 2 Polar Marine Geological Research Expedition, Pobedy 24, 198412 St. Petersburg, Russia 3 Zakład Biologii Antarktyki PAN, Ustrzycka 10/12, 02−141 Warszawa, Poland Abstract: The Panorama Point Beds represent a subfacies of the Early to Middle Permian Radok Conglomerate, which is the oldest known sedimentary unit in the Prince Charles Mountains, MacRobertson Land, East Antarctica. This unit records clastic sedimentation in fresh−water depositional system during the early stages of development of the Lambert Graben, a major structural valley surrounded by crystalline highlands in the southern part of Gondwana. It contains common siderite precipitated through early diagenetic processes in the swamp, stagnant water, and stream−flow environments. There are two types of siderite in the Panorama Point Beds: (1) disseminated cement that occurs throughout the sedimentary suc− cession; and (2) concretions that occur at recurrent horizons in fine−grained sediments. The cement is composed of Fe−depleted siderite (less than 90 mol % FeCO3) with an elevated con− d13 tent of magnesium, and trace and rare earth elements. It has negative CVPDB values (−4.5 to −1.5‰). The concretions are dominated by Fe−rich siderite (more than 90 mol % FeCO3), with d13 positive CVPDB values (+1 to +8‰). -
Ocean Drilling Program Scientific Results Volume
Barron, J., Larsen, B., et al., 1991 Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 119 3. DEPOSITIONAL ENVIRONMENT AND PETROGRAPHY OF PREGLACIAL CONTINENTAL SEDIMENTS FROM HOLE 740A, PRYDZ BAY, EAST ANTARCTICA1 Brian R. Turner2 ABSTRACT ODP Hole 740A is located on the inner part of the East Antarctic continental shelf in Prydz Bay, at the seaward end of a major onshore rift structure known as the Lambert Graben. Drilling at this site led to the recovery of some 65 m of continental sediments (Prydz Bay red beds) that form part of a much thicker (2-3 km) pre-continental breakup se- quence, the development of which may be related to the initiation and rifting of the Lambert Graben. Palynological and paleomagnetic studies have not been able to determine the age of the sediments; they may be equivalent to the onshore late Permian Amery Group or younger. The succession consists predominantly of sandstone, siltstone, and claystone ar- ranged in erosively based, pedogenically influenced fining-upward sequences up to 5 m thick. These were deposited by shallow, braided streams draining an extensively vegetated alluvial plain, with sufficient topographic relief to trap fine- grained sediment and inhibit rapid channel shifting. Pedogenic processes were initiated on the alluvial plain, but cli- matic conditions were generally unsuitable for extensive pedogenic carbonate formation and the development of mature soil profiles. The sediments were probably derived from a rapidly uplifted fault block terrain composed of upper Pro- terozoic and Archaean gneisses lying to the southeast of the depositional site. Uplift may have taken place along the tec- tonically active seaward extension of the eastern faulted margin of the Lambert Graben, which passes immediately southeast of Hole 740A. -
(Eastern Lambert Graben, Antarctica) As Indicated by Apatite Fission Track Data and Geomorphological Observation F
U.S. Geological Survey and The National Academies; USGS OF-2007-1047, Short Research Paper 105; doi:10.3133/of2007-1047.srp105 Denudation and uplift of the Mawson Escarpment (eastern Lambert Graben, Antarctica) as indicated by apatite fission track data and geomorphological observation F. Lisker,1 H. Gibson,2 C. J. Wilson,3 and A. Läufer4 1Universität Bremen, FB 5, Postfach 330440, 28334 Bremen, Germany ([email protected]) 2GeoIntrepid, Unit 2, 1 Male Street, Brighton, Victoria 3186, Australia 3School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia 4Bundesanstalt für Geowissenschaften und Rohstoffe, Postfach 510153, 30631 Hannover, Germany Abstract Analysis of three vertical profiles from the southern Mawson Escarpment (Lambert Graben) reveals apatite fission track (AFT) ages ranging from 102±20 to 287±23 Ma and mean lengths of 12.2 to 13.0 µm. Quantitative thermal histories derived from these data consistently indicate onset of slow cooling below 110°C began sometime prior to 300 Ma, and a second stage of rapid cooling from paleotemperatures up to ≤100°C to surface temperatures occurred in the Late Cretaceous – Paleocene. The first cooling phase refers to Carboniferous – Jurassic basement denudation up to 5 km associated with the initial rifting of the Lambert Graben. The presence of the ancient East Antarctic Erosion Surface and rapid Late Cretaceous – Paleocene cooling indicate a second denuda- tional episode during which up to 4.5 km of sedimentary cover rocks were removed, and that is likely linked to the Cretaceous Gondwana breakup between Antarctica and India and subsequent passive continental margin formation. Citation: Lisker, F., , H.