DOCSLIB.ORG

Himalayan Tectonics, Weatheuing Puocesses, and the Stuontium

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Himalayan Tectonics, Weatheuing Puocesses, and the Stuontium +LPDOD\DQ7HFWRQLFV:HDWKHULQJ3URFHVVHVDQGWKH6WURQWLXP,VRWRSH5HFRUGLQ0DULQH /LPHVWRQHV $XWKRU V -0(GPRQG 6RXUFH6FLHQFH1HZ6HULHV9RO1R 'HF SS 3XEOLVKHGE\American Association for the Advancement of Science 6WDEOH85/http://www.jstor.org/stable/2882056 . $FFHVVHG Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at . http://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at . http://www.jstor.org/action/showPublisher?publisherCode=aaas. Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. American Association for the Advancement of Science is collaborating with JSTOR to digitize, preserve and extend access to Science. http://www.jstor.org Himalayan Tectonics, Weathering Processes, and the Strontium Isotope Record in Marine Limestones J. M. Edmond The time evolution of the isotopic composition of seawater strontium (the ratio of strontium- these variablesare causallyrelated, it has 87 to strontium-86) over the last 500 million years has the form of an asymmetric trough. not proved possible to develop an unam- The values are highest in the Cambrian and Recent (0.7091) and lowest in the Jurassic biguous and specific interpretationof the (0.7067). Superimposed on this trend are a number of smaller oscillations. Consideration isotope recordin terms of explicit mecha- of the geochemical cycle of strontium and the dynamics of weathering shows that only nisms. The consensusis that variationsin Himalayan-style continental collisions can influence the isotope ratio on the scale ob- the intensity of continental weathering served. The contemporary Himalayan orogeny is by far the largest since the late Pre- are important, although this notion has cambrian Pan-African event that produced the high in the Cambrian. not been developed in any detail. The average isotope ratio of Sr in the fluvial flux from the weathering of lime- stones and evaporites over the period of Variationsin the isotopiccomposition of past (4). Observationsindicate that the record varied between about 0.7075 and strontiumin seawater,recorded in marine fluvialflux is dominatedby the weathering 0.7080, a quite narrow range (4). The limestones, are a proxy of the interplayof of platform carbonatesand evaporites of long residencetime of Sr in the limestone mantle processesand crustal weathering. marine origin. There is only a minor reservoiracts strongly to damp the signal Wickmanoriginally proposed that Rb (the contributionfrom the primaryweathering from the relatively high-frequencymarine radioactiveparent of 87Sr, half-life -48 of the refractoryigneous and metamorphic isotopic oscillations (-50 million years). billion years), as an incompatibleelement, basement rocks (5). Hence, the memory Contemporaryoceanic hot springshave a should be progressivelyenriched in conti- effect is dominant. uniform ratio of about 0.7035, which nental crustalrocks over geologic time rel- A synthetic stratigraphiccolumn com- probablyhas not varied over the last 500 ative to Sr (1). Hence, Sr from fluvial posedof marinelimestones has been assem- million years (3). On the basis of the sea inputsto the ocean shouldbecome increas- bled that is continuousover the past 500 floor spreading record of the last 150 ingly radiogenic, leading to a monotonic million years (6). The Sr isotopicrecord of million years, the hydrothermalflux has increasein the isotopiccomposition of Sr in seawaterderived from this column is char- changed slowly and continuously but seawater.Wickman was the first to recog- acterizedby largeoscillations on a varietyof probablyless than ?30% (8), an amount nize that the record of this increase, pre- time scales (Fig. 2). Values of the 87Srto insufficientto resultin any markedchange servedin marinesediments, could be used 86Sr ratio were high in the Cambrian in the isotopic record. Hence, strong fea- for dating, particularlyof limestones and (-0.7091) but declined irregularlyuntil tures in the record most likely reflect evaporites(1). This latteridea has recently the late Jurassic(-0.7067). Several inter- continental processes.Given that the av- been revivedand appliedwith some success mediate-scalefluctuations are superimposed erage Sr flux from limestones has isotopic (2) (Fig. 1). However, the isotopicsystem- on this trend. The continuation of these ratios between the extrema of the oscilla- atics are much more complex than Wick- oscillationsin the Cretaceousand Tertiary man could have realized. was interruptedin the mid-Tertiaryby a The isotopic composition of Sr in sea- steep rise that has continued until the 0.7093 water at any time is determined by the present time (Fig. 1). The contemporary balance between the deep-sea hydrother- seawaterratio (0.7091) is the same as that mal input of nonradiogenicSr of mantle at the height of the Cambrianand is sub- origin (-0.7035) and the more radiogenic stantially higher than at any intervening fluvial flux derived from continental time. These observationsare completelyat weathering(-0.712) (3). The majorsink variancewith the originallinear evolution for Sr is marine carbonaterocks; incorpo- model (1). ration in the carbonatesinvolves no iso- In attempts to explain the features in topic fractionation.The residencetime of the isotope curve, correlationshave been Sr in this limestone reservoir is on the claimedwith many events contained in or (0*0 orderof 150 million years (and in seawater inferredfrom the geologic record (2, 7). 0~~~~~~~~~~~~~~ -3 million years) (3). Variations in the Changes in the fluvial inputs have been continental signal, caused by the dissolu- attributedto variationsin continental gla- 0~~~~~~~~~~~~~~ tion of igneous and metamorphicrocks, ciation, eustatic sea level, atmospheric OR are thereforedamped by the weatheringof CO2 levels, climate, vegetation, and these carbonatesafter exposurecaused by mountain building, individually or in changesin eustaticsea level or by tectonic combination. For time periods before uplift. Because of the weathering of car- about 100 million years ago where the 0.707",'0 20 40 60 80 100 bonates, the fluvial flux retains a "memo- paleomagneticrecord provides little con- Age (millions of years) ry"of isotopic fluctuationsin the geologic straint, changes have been claimed be- Fig. 1. High-resolutionisotope ratio curve for cause of substantialvariations in the oce- The author is in the Department of Earth, Atmospheric, abyssal carbonates over the past 100 million and Planetary Sciences, Massachusetts Institute of anic hydrothermalflux and hence the sea years based on drill core samples [modified Technology, E34-201, Cambridge, MA 02139. floor spreading rate. Because many of from (2)]. The chronometricpotential is clear. 1594 SCIENCE * VOL. 258 * 4 DECEMBER1992 tions and that deviations, such as the Strontium in Rivers global reconnaissance(3, 12). The funda- recent one, extend well above this range, mental resultis that exposedigneous base- the fundamentalvariable is the weather- A large amount of data exists on the Sr ment terrains, in continental shields, do ing yield of radiogenic Sr from old base- systematicsin rivers that characterizethe not yield radiogenicSr in high flux, even ment rocks. To the first order, the prob- relationsamong the Sr flux, the Sr isotope when the rocks are highly alkalic and of lem is reduced to the identification of ratio of the riversand oceans, the geologic greatage. This is trueof both deeplyweath- distinct processes that produce a high events, and weathering environments ered, lateritic soils from basement in the fluvial flux of radiogenic Sr and operate where Sr is releasedfor transport.A num- Tropics,such as that foundin the Guyana, repeatedlyover discrete intervals of geo- ber of local studiesare available(9), along Brazilian,and southernAfrican shields (3, logic time. with some regionalones (10, 11) and one 12), and recently glaciated terrains, as foundin easternCanada (10). Of the other siliceousrocks (12), black shalescan give a high dissolved yield as a result of acid 0.71019]Tertiary Cretaceous Jurassic TdasIc PerrmanPenn] Mbis.sDevonianSilurian Ordoviciancam weathering associatedwith sulfide oxida- tion; basic rocks also weather rapidlybe- cause of the oxidative breakdownof mafic minerals.However, the Sr that is releasedis 0.709 _ not radiogenicbecause of the usualadmix- ture of carbonaterocks in black shales and the mantle affinitiesof volcanic rocks. The only observedexception to this generaliza- 0.708~ - tion is the metamorphiccore complexfrom the centralHimalaya, which influencesthe CD Gangesand Brahmaputrarivers (3, 11, 12). 00 0 Data from a wide varietyof geologic envi- ronments (Fig. 3, A and B) define a uni- form shallowincrease in the isotopic com- 0.70671 position as
Load more

Recommended publications
  • Article of a Given In- with Postdepositional Erosion
    Earth Surf. Dynam., 8, 769–787, 2020 https://doi.org/10.5194/esurf-8-769-2020 © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License. Timing of exotic, far-traveled boulder emplacement and paleo-outburst flooding in the central Himalayas Marius L. Huber1,a, Maarten Lupker1, Sean F. Gallen2, Marcus Christl3, and Ananta P. Gajurel4 1Geological Institute, Department of Earth Sciences, ETH Zurich, Zurich 8092, Switzerland 2Department of Geosciences, Colorado State University, Fort Collins, Colorado 80523, USA 3Laboratory of Ion Beam Physics (LIP), Department of Physics, ETH Zurich, Zurich 8093, Switzerland 4Department of Geology, Tribhuvan University, Kirtipur, Kathmandu, Nepal acurrent address: Université de Lorraine, CNRS, CRPG, 54000 Nancy, France Correspondence: Marius L. Huber ([email protected]) Received: 28 February 2020 – Discussion started: 20 March 2020 Revised: 21 July 2020 – Accepted: 11 August 2020 – Published: 22 September 2020 Abstract. Large boulders, ca. 10 m in diameter or more, commonly linger in Himalayan river channels. In many cases, their lithology is consistent with source areas located more than 10 km upstream, suggesting long trans- port distances. The mechanisms and timing of “exotic” boulder emplacement are poorly constrained, but their presence hints at processes that are relevant for landscape evolution and geohazard assessments in mountainous regions. We surveyed river reaches of the Trishuli and Sunkoshi, two trans-Himalayan rivers in central Nepal, to improve our understanding of the processes responsible for exotic boulder transport and the timing of em- placement. Boulder size and channel hydraulic geometry were used to constrain paleo-flood discharge assuming turbulent, Newtonian fluid flow conditions, and boulder exposure ages were determined using cosmogenic nu- clide exposure dating.
    [Show full text]
  • Sediment Transport to the Laptev Sea-Hydrology and Geochemistry of the Lena River
    Sediment transport to the Laptev Sea-hydrology and geochemistry of the Lena River V. RACHOLD, A. ALABYAN, H.-W. HUBBERTEN, V. N. KOROTAEV and A. A, ZAITSEV Rachold, V., Alabyan, A., Hubberten, H.-W., Korotaev, V. N. & Zaitsev, A. A. 1996: Sediment transport to the Laptev Sea-hydrology and geochemistry of the Lena River. Polar Research 15(2), 183-196. This study focuses on the fluvial sediment input to the Laptev Sea and concentrates on the hydrology of the Lena basin and the geochemistry of the suspended particulate material. The paper presents data on annual water discharge, sediment transport and seasonal variations of sediment transport. The data are based on daily measurements of hydrometeorological stations and additional analyses of the SPM concentrations carried out during expeditions from 1975 to 1981. Samples of the SPM collected during an expedition in 1994 were analysed for major, trace, and rare earth elements by ICP-OES and ICP-MS. Approximately 700 h3freshwater and 27 x lo6 tons of sediment per year are supplied to the Laptev Sea by Siberian rivers, mainly by the Lena River. Due to the climatic situation of the drainage area, almost the entire material is transported between June and September. However, only a minor part of the sediments transported by the Lena River enters the Laptev Sea shelf through the main channels of the delta, while the rest is dispersed within the network of the Lena Delta. Because the Lena River drains a large basin of 2.5 x lo6 km2,the chemical composition of the SPM shows a very uniform composition.
    [Show full text]
  • Assessment of Undiscovered Conventionally Recoverable Petroleum Resources of the Northwest European Region
    U.S. GEOLOGICAL SURVEY CIRCULAR 922-A Assessment of Undiscovered Conventionally Recoverable Petroleum Resources of the Northwest European Region Assessment of Undiscovered Conventionally Recoverable Petroleum Resources of the North\Nest European Region By Charles D. Masters and H. Douglas Klemme U. S. G E 0 L 0 G I CAL SURVEY CIRCULAR 9 2 2- A Prepared in cooperation with Weeks Exploration Company under contract to the U.S. Geological Survey A resource assessment and a brief description of the petroleum geology, including play distribution, that accounts for the petroleum accumulation in the North Sea and adjoining areas 1984 Department of the Interior WILLIAM P. CLARK, Secretary U.S. Geological Survey Dallas L. Peck, Director Free on application to Distribution Branch, Text Products Section, U. S. Geological Survey, 604 South Pickett Street, Alexandria, VA 22304 CONTENTS Page Pref~--------------------------------------------------------------------- v Absttact-------------------------------------------------------------------- 1 Inbuduction ---------------------------------------------------------------- 1 Regional geology ------------------------------------------------------------- 2 Pettoleum geology ------------------------------------------------------------ 6 Resource assessment---------------------------------------------------------- 14 COmmen~ ------------------------------------------------------------------ 15 References cited -------------------------------------------------------------- 22 ILLUSTRATIONS Page FIGURE 1. Map
    [Show full text]
  • GY 112 Lecture Notes D
    GY 112 Lecture Notes D. Haywick (2006) 1 GY 112 Lecture Notes Archean Geology Lecture Goals: A) Time frame (the Archean and earlier) B) Rocks and tectonic elements (shield/platform/craton) C) Tectonics and paleogeography Textbook reference: Levin 7th edition (2003), Chapter 6; Levin 8th edition (2006), Chapter 8 A) Time frame Up until comparatively recently (start of the 20th century), most geologists focused their discussion of geological time on two eons; the “Precambrian” and the Phanerozoic. We now officially recognize 4 eons and the Precambrian is just used as a come-all term for all time before the Phanerozoic: Eon Time Phanerozoic 550 MA to 0 MA Proterozoic 2.5 GA to 550 MA Archean 3.96 GA to 2.5 GA Hadean 4.6 GA to 3.96 GA The “youngest” of these two new eons, the Archean, was first introduced by field geologists working in areas where very old rocks cropped out. One of these geologists was Sir William Logan (pictured at left; ess.nrcan.gc.ca ) one of the most respected geologists working with the Geological Survey of Canada. His study area was the Canadian Shield. Logan was able to identify two major types of rocks; 1) layered sedimentary and volcanic rocks and 2) highly metamorphosed granitic gneisses (see image at the top of the next page from http://www.trailcanada.com/images/canadian-shield.jpg). Logan found evidence that the gneisses mostly underlayed the layered rocks and hence, they had to be older than the layered rocks. The layered rocks were known to be Proterozoic in age.
    [Show full text]
  • Molecular Evidence for Pervasive Riverine Export of Soil Organic Matter from the Central Himalaya
    EGU2020-9017 https://doi.org/10.5194/egusphere-egu2020-9017 EGU General Assembly 2020 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. Molecular evidence for pervasive riverine export of soil organic matter from the Central Himalaya Lena Märki1, Maarten Lupker1, Ananta Gajurel2, Hannah Gies1, Negar Haghipour1,3, Sean Gallen4, Christian France-Lanord5, Jérôme Lavé5, and Timothy Eglinton1 1ETH Zurich, Geological Institute, Department of Earth Sciences, Zurich, Switzerland ([email protected]) 2Tribhuvan University, Department of Geology, Kathmandu, Nepal 3ETH Zurich, Ion Beam Physics, Zurich, Switzerland 4Colorado State University, Department of Geosciences, Fort Collins, USA 5CNRS – Université de Lorraine, Centre de Recherches Pétrographiques et Géochimiques, Vandœuvre-lès-Nancy, France Soil erosion in high mountain ranges plays an important role in redistributing soil organic carbon across landscapes and may influence the global climate on different timescales [1, 2]. Here, we investigate the dynamics of soil organic matter export in the steep mountain belt of the Himalaya by tracing the provenance of soil-derived lipids in riverine sediments from nested catchments with areas ranging from 370 to 57700 km2. Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are a suite of lipids that occur ubiquitously in soils [3, 4]. Their isomer distribution depends on environmental parameters such as the mean annual temperature of the local environment [3]. In this study, we explore the use of brGDGT distributions as a proxy for the altitudinal provenance of soil organic matter in riverine sediments of the Central Himalaya of Nepal. BrGDGT distributions in soils collected along an altitudinal profile, spanning elevations from 200 to 4450 m asl, yield a robust calibration of soil signatures as a function of elevation.
    [Show full text]
  • Periodicity of Rayleigh Phase Velocities Observed in Scandinavia
    Originally published as: Mauerberger, A., Maupin, V., Gudmundsson, Ó., Tilmann, F. (2021): Anomalous azimuthal variations with 360° periodicity of Rayleigh phase velocities observed in Scandinavia. - Geophysical Journal International, 224, 3, 1684-1704. https://doi.org/10.1093/gji/ggaa553 Institutional Repository GFZpublic: https://gfzpublic.gfz‐potsdam.de/ Geophys. J. Int. (2021) 224, 1684–1704 doi: 10.1093/gji/ggaa553 Advance Access publication 2020 November 13 0GJI Seismology Anomalous azimuthal variations with 360◦ periodicity of Rayleigh phase velocities observed in Scandinavia Downloaded from https://academic.oup.com/gji/article/224/3/1684/6012847 by Bibliothek des Wissenschaftsparks Albert Einstein user on 12 February 2021 Alexandra Mauerberger ,1,2 Valerie´ Maupin ,3 Olafur´ Gudmundsson4 and Frederik Tilmann 1,2 1GFZ German Research Center for Geosciences, Geophysics, Telegrafenberg, 14473 Potsdam, Germany. E-mail: [email protected] 2Freie Universitat¨ Berlin, Institute of Geological Sciences, 12249 Berlin, Germany 3University of Oslo, CEED, 0371 Oslo, Norway 4 Uppsala University, Geocentrum, 752 36 Uppsala, Sweden Accepted 2020 November 13. Received 2020 November 6; in original form 2020 February 27 SUMMARY We use the recently deployed ScanArray network of broad-band stations covering most of Norway and Sweden as well as parts of Finland to analyse the propagation of Rayleigh waves in Scandinavia. Applying an array beamforming technique to teleseismic records from ScanArray and permanent stations in the study region, in total 159 stations with a typical station distance of about 70 km, we obtain phase velocities for three subregions, which collectively cover most of Scandinavia (excluding southern Norway). The average phase dispersion curves are similar for all three subregions.
    [Show full text]
  • 1 Lena Kolarska-Bobińska Completed Transformation: Integration Into the European Union for the Countries of Central and Eastern
    Lena Kolarska-Bobiska Completed Transformation: integration into the European Union For the countries of Central and Eastern Europe full integration with the European Union will constitute the crowning moment of their as yet unfinished economic and political transformation. The EU integration process will also become a crucial driving force for changes of the social structure, institutions and group interests whose new framework have been emerging since the fall of the Communist system. This fact that integration into the EU is the final stage of transformation of the candidate countries and not merely a process of adapting to external conditions makes the present enlargement quite different to anything experienced before. When Sweden or Austria sought to join the Western European community their societies had a stable social structure and well-formed and effectively functioning democratic and financial institutions. In their case integration meant no more than adaptation of well developed and stable social systems to some new norms and circumstances and not as in the former Communist run countries the continuation of radical political and social changes. Poland, the Czech Republic and Hungary are countries were a new social order and social structures are emerging. As integration is a driving force for change and is dictating its direction it will have an basic impact on the final character of those societies. In this paper I would focus on the social changes which Poland faces as a result of the integration process and their impact on the evolution of attitudes to membership in the European Union. THE FIRST STAGE OF TRANSFORMATION: FROM ANOMY TO ADAPTATION (1989-1997) The changes in Poland followed a slightly different pattern from those in Hungary or the Czech Republic.
    [Show full text]
  • Tectonic Regimes in the Baltic Shield During the Last 1200 Ma • a Review
    Tectonic regimes in the Baltic Shield during the last 1200 Ma • A review Sven Åke Larsson ' ', Bva-L^na Tuliborq- 1 Department of Geology Chalmers University of Technology/Göteborij U^vjrsivy 2 Terralogica AB November 1993 TECTONIC REGIMES IN THE BALTIC SHIELD DURING THE LAST 1200 Ma - A REVIEW Sven Åke Larsson12, Eva-Lena Tullborg2 1 Department of Geology, Chalmers University of Technology/Göteborg University 2 Terralogica AB November 1993 This report concerns a study which was conducted for SKB. The conclusions and viewpoints presented in the report are those of the author(s) and do not necessarily coincide with those of the client. Information on SKB technical reports from 1977-1978 (TR 121), 1979 (TR 79-28), 1980 (TR 80-26), 1981 (TR 81-17), 1982 (TR 82-28), 1983 (TR 83-77), 1984 (TR 85-01), 1985 (TR 85-20), 1986 (TR 86-31), 1987 (TR 87-33), 1988 (TR 88-32),. 1989 (TR 89-40), 1990 (TR 90-46), 1991 (TR 91-64) and 1992 (TR 92-46) is available through SKB. ) TECTONIC REGIMES IN THE BALTIC SHIELD DURING THE LAST 1200 Ma - A REVIEW by Sven Åke Larson and Eva-Lena Tullborg Department of Geology, Chalmers University of Technology / Göteborg University & Terralogica AB Gråbo, November, 1993 Keywords: Baltic shield, Tectonicregimes. Upper Protero/.oic, Phanerozoic, Mag- matism. Sedimentation. Erosion. Metamorphism, Continental drift. Stress regimes. , ABSTRACT 1 his report is a review about tectonic regimes in the Baltic (Fennoscandian) Shield from the Sveeonorwegian (1.2 Ga ago) to the present. It also covers what is known about palaeostress during this period, which was chosen to include both orogenic and anorogenic events.
    [Show full text]
  • South and North Barents Triassic-Jurassic Total Petroleum System of the Russian Offshore Arctic
    U. S. Department of the Interior U. S. Geological Survey South and North Barents Triassic-Jurassic Total Petroleum System of the Russian Offshore Arctic Paper Edition by Sandra J. Lindquist1 Open-File Report 99-50-N This report is preliminary and has not been reviewed for conformity with the U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 1999 1 Consulting Geologist, Contractor to U. S. Geological Survey, Denver, Colorado Page 1 of 16 South and North Barents Triassic-Jurassic Total Petroleum System of the Russian Offshore Arctic2 Sandra J. Lindquist, Consulting Geologist Contractor to the U.S. Geological Survey, Denver, CO October, 1999 FOREWORD This report was prepared as part of the World Energy Project of the U.S. Geological Survey. In the project, the world was divided into 8 regions and 937 geologic provinces. The provinces have been ranked according to the discovered oil and gas volumes within each (Klett and others, 1997). Then, 76 "priority" provinces (exclusive of the U.S. and chosen for their high ranking) and 26 "boutique" provinces (exclusive of the U.S. and chosen for their anticipated petroleum richness or special regional economic importance) were selected for appraisal of oil and gas resources. The petroleum geology of these priority and boutique provinces is described in this series of reports. A detailed report containing the assessment results will be available separately, if such results are not reported herein. The priority South Barents Basin Province ranks 35th in the world, exclusive of the U.S.
    [Show full text]
  • Moisture Origin As a Driver of Temporal Variabilities of The
    https://doi.org/10.5194/acp-2019-942 Preprint. Discussion started: 6 January 2020 c Author(s) 2020. CC BY 4.0 License. Moisture origin as a driver of temporal variabilities of the water vapour isotopic composition in the Lena River Delta, Siberia Jean-Louis Bonne1, Hanno Meyer2, Melanie Behrens1, Julia Boike2,3, Sepp Kipfstuhl1, Benjamin Rabe1, Toni Schmidt2, Lutz Schönicke2, Hans Christian Steen-Larsen4, Martin Werner1 5 1Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, 27515 Germany 2Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Potsdam, 14401, Germany 3Geography Department, Humboldt-Universität zu Berlin, Berlin, 10099, Germany 4Geophysical Institute, University of Bergen, and Bjerknes Centre for Climate Research, Bergen, 5020, Norway Correspondence to: Jean-Louis Bonne ([email protected]), Martin Werner ([email protected]) 10 Abstract. In the context of the Arctic amplification of climate change affecting the regional atmospheric hydrological cycle, it is crucial to characterize the present-day’s moisture sources of the Arctic. The isotopic composition is an important tool to enhance our understanding of the drivers of the hydrological cycle, due to the different molecular characteristics of water stable isotopes during phase change. This study introduces two years of continuous in situ water vapour and precipitation isotopic observations conducted since July 2015 in the east-Siberian Lena delta, at the research station on the Samoylov 15 Island. The vapour isotopic signals are dominated by variations at the seasonal and synoptic time scales. Diurnal variations of the vapour isotopic signals are masked by synoptic variations, indicating low variations of the amplitude of local sources at the diurnal scale in winter, summer and autumn.
    [Show full text]
  • Rutile Mineral Chemistry and Zr-In-Rutile Thermometry In
    minerals Article Rutile Mineral Chemistry and Zr-in-Rutile Thermometry in Provenance Study of Albian (Uppermost Lower Cretaceous) Terrigenous Quartz Sands and Sandstones in Southern Extra-Carpathian Poland Jakub Kotowski * , Krzysztof Nejbert and Danuta Olszewska-Nejbert Faculty of Geology, University of Warsaw, Zwirki˙ i Wigury 93, 02-089 Warszawa, Poland; [email protected] (K.N.); [email protected] (D.O.-N.) * Correspondence: [email protected] Abstract: The geochemistry of detrital rutile grains, which are extremely resistant to weathering, was used in a provenance study of the transgressive Albian quartz sands in the southern part of extra-Carpathian Poland. Rutile grains were sampled from eight outcrops and four boreholes located on the Miechów, Szydłowiec, and Puławy Segments. The crystallization temperatures of the rutile grains, calculated using a Zr-in-rutile geothermometer, allowed for the division of the study area into three parts: western, central, and eastern. The western group of samples, located in the Citation: Kotowski, J.; Nejbert, K.; Miechów Segment, is characterized by a polymodal distribution of rutile crystallization temperatures ◦ ◦ ◦ Olszewska-Nejbert, D. Rutile Mineral (700–800 C; 550–600 C, and c. 900 C) with a significant predominance of high-temperature forms, Chemistry and Zr-in-Rutile and with a clear prevalence of metapelitic over metamafic rutile. The eastern group of samples, Thermometry in Provenance Study of corresponding to the Lublin Area, is monomodal and their crystallization temperatures peak at Albian (Uppermost Lower 550–600 ◦C. The contents of metapelitic to metamafic rutile in the study area are comparable. The Cretaceous) Terrigenous Quartz central group of rutile samples with bimodal distribution (550–600 ◦C and 850–950 ◦C) most likely Sands and Sandstones in Southern represents a mixing zone, with a visible influence from the western and, to a lesser extent, the eastern Extra-Carpathian Poland.
    [Show full text]
  • Late Quaternary Sedimentation History of the Lena Delta Georg Schwamborna,*, Volker Racholda, Mikhail N
    Quaternary International 89 (2002) 119–134 Late Quaternary sedimentation history of the Lena Delta Georg Schwamborna,*, Volker Racholda, Mikhail N. Grigorievb a Alfred Wegener Institute for Polar and Marine Research, Telegrafenberg A43, D-14473 Potsdam, Germany b Permafrost Institute, Russian Academyof Sciences, 677018 Yakutsk, Yakutia, Russia Abstract Core and outcrop analysis from Lena mouth deposits have been used to reconstruct the Late Quaternary sedimentation history of the Lena Delta. Sediment properties (heavy mineral composition, grain size characteristics, organic carbon content) and age determinations (14C AMSand IR-OSL)are applied to discriminate the main sedimentary units of the three major geomorphic terraces, which form the delta. The development of the terraces is controlled by complex interactions among the following four factors: (1) Channel migration. According to the distribution of 14C and IR-OSL age determinations of Lena mouth sediments, the major river runoff direction shifted from the west during marine isotope stages 5–3 (third terrace deposits) towards the northwest during marine isotope stage 2 and transition to stage 1 (second terrace), to the northeast and east during the Holocene (first terrace deposits). (2) Eustasy. Sea level rise from Last Glacial lowstand to the modern sea level position, reached at 6–5 ka BP, resulted in back-filling and flooding of the palaeovalleys. (3) Neotectonics. The extension of the Arctic Mid-Ocean Ridge into the Laptev Sea shelf acted as a halfgraben, showing dilatation movements with different subsidence rates. From the continent side, differential neotectonics with uplift and transpression in the Siberian coast ridges are active. Both likely have influenced river behavior by providing sites for preservation, with uplift, in particular, allowing accumulation of deposits in the second terrace in the western sector.
    [Show full text]