River Deltas-Concepts, Models, and Examples. SEPM Special Publication, Vol. 83. 2005. 502 pp. ISBN: 1-56576-113-8. DOI: 10.2110/pec.05.83. Depositional Patterns in the Late Holocene Po Delta System ANNAMARIA CORREGGIARI, ANTONIO CATTANEO and FABIO TRINCARDI P.365-392 Instituto di Scienze Marine Consiglio Nazionale delle Ricerche Sezione di Bologna, ISMAR (CNR) v. Gobetti 101, 40129 Bologna, Italia,
[email protected] The late Holocene Po delta system is fed by the Po river, which drains the E–W-trending Po plain 2
(catchment area 74,500 km ) and enters the Adriatic epicontinental sea. The Po delta system inc ludes an extensive delta plain, a wave-influenced delta front, and a broad asymmetric prodelta deposit. The prodelta shows a steeper and shorter slope to the north and a very gentle slope to the south, where the thick Po prodelta merges into the late Holocene Adriatic mud wedge. The growth of the late Holocene Po delta started 5.5 kyr BP, after the present sea-level highstand was attained. The Po delta was characterized by alternating phases of rapid advance and abandonment of its multiple deltaic lobes. This delta history reflects the forcing of high-frequency climate change, autocyclic avulsions, and anthropogenic factors, acting on variable, but typically short, time scales.The Po system has been investigated through: (1) a review of historical cartography extending back several centuries; (2) integrated surveys of VHR seismic profiles recorded offshore of the modern delta from water depths as shallow as 5 m to the toe of the prodelta in about 30 m; and (3) sedimentological and geochronological data from precisely positioned sediment cores.Historical ac counts and cartography show that avulsion was an important process in Po delta building, during highstand progradation; with reference to the position of the present-day Po delta, older elements developed both to the north and to the south. During the late Bronze Age (ca. 3 kyr BP), the Po river developed two main branches: the Po di Adria, in the northern sector, and the Po di Spina, to the south. During the Roman Age (ca. 2.5– 1.5 kyr BP) two other branches became dominant, both in the southern sector: the Po di Eridano and the Po di Olano. During the Middle Ages, Po di Primaro activated slightly south of the Po di Eridano,
and at the same time the Po di Ariano branch developed to the north. The Ficarolo avulsion (12
th
century, ca. 800 yr BP) shifted the main distributary channel farther to the north, activating the Po delle Fornaci, and threatening the Venice lagoon with siltation over the following centuries. The Porto Viro cut by the Venice Republic (1600–1604 AD, ca. 350 yr BP) redirected the northern branch of the Po to a southern outlet (Po Grande), initiating the rapid formation of the Modern Po delta with a protruding morphology on the western Adriatic coast. The rapid outbuilding of the Modern Po delta with rates up to 129 m yr
−1
reflects the impact of the Little Ice Age (1450–1850 AD, ca. 500–100 yr
BP), probably enhanced by anthropogenic forcing of the river regime. The reconstruction of the stratigraphy of the Po prodelta and the correlation to geomorphologic and historical data in the delta plain show: (a) a marked asymmetry of the delta–prodelta system with significant down-drift sediment dispersal to the south of each individual delta mouth and asymmetric prodelta lobes; (b) short-term shifts from supply-dominated to wave-dominated delta lobes; and (c) the presence of two markedly distinct depositional elements in the prodelta. The two main kinds of prodelta deposits are: (1) shingled depositional prodelta lobes characterized by laterally continuous seismic reflectors showing evidence of variably preserved flood deposits in core, and (2) depositional prodelta lobes accompanied by “cut-and-fill” features typically detected offshore of short-lived, very active distributary channels characterized by massive silt in core. In the first kind of prodelta deposit, individual lobes onlap each other laterally, reflecting changes in the relative importance of their feeding systems over short intervals. In the second case, seismic profiles indicate that the channel-like forms have sharp bases and record repeated episodes of cut and fill while the entire lobe is building. The channel-like features typically occur in clusters, with individual widths ranging from 100 to 300 m and depths up to 4–5 m, filled with massive silt to very fine sand. The short-lived episodes of cut and fill are hypothetically attributed to episodic flood events of catastrophic reactivation of distinctive Po river branches driven by sudden increases in river discharge of natural origin or by human intervention.
RIVER DELTAS—CONCEPTS, MODELS, AND EXAMPLES Proximal Floodplain
Subtidal to intertidal flat
Distal
Beach ridge
Mangrove forest
WAVE Sand TIDE
Mud
Longshore sediment dispersal
Delta front (steep slope)
Pleistocene deposit
Edited by: LIVIU GIOSAN Department of Geology and Geophysics, Woods Hole Oceanographic Institution, MS #22, Woods Hole, Massachusetts, 02543, U.S.A. AND
JANOK P. BHATTACHARYA Department of Geosciences, University of Texas at Dallas, P.O. Box 830688, Richardson, Texas 75083-0688, U.S.A.
Copyright 2005 by SEPM (Society for Sedimentary Geology) Laura J. Crossey, Editor of Special Publications SEPM Special Publication 83
Tulsa, Oklahoma, U.S.A.
August, 2005
SEPM and the authors are grateful to the following for their generous contribution to the cost of publishing River Deltas—Concepts, Models, and Examples
University of Aberdeen CASP Coastal Ocean Institute and Reinhart Coastal Research Center at the Woods Hole Oceanographic Institution The Mr. & Mrs. J.B. Coffman Endowment in Sedimentary Geology at the University of Nebraska-Lincoln Natural Sciences and Engineering Research Council of Canada
Contributions were applied to the cost of production, which reduced the purchase price, making the volume available to a wide audience
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RIVER DELTAS—CONCEPTS, MODELS, AND EXAMPLES Liviu Giosan and Janok P. Bhattacharya, Editors
CONTENTS Introduction New directions in deltaic studies LIVIU GIOSAN AND JANOK P. BHATTACHARYA ............................................................................................................................... 3
Concepts and Reviews Three-dimensional numerical modeling of deltas IRINA OVEREEM, JAMES P.M. SYVITSKI, AND ERIC W.H. HUTTON ............................................................................................. 13 Lithostratigraphy versus chronostratigraphy in facies correlations of Quaternary deltas: Application of bedding correlation M. ROYHAN GANI AND JANOK P. BHATTACHARYA ...................................................................................................................... 31 Ichnology of deltas: Organism responses to the dynamic interplay of rivers, waves, storms, and tides JAMES A. MACEACHERN, KERRIE L. BANN, JANOK P. BHATTACHARYA, AND CHARLES D. HOWELL, JR. ................... 49 Deposits of tide-influenced river deltas BRIAN J. WILLIS ......................................................................................................................................................................................... 87
Ancient Deltas (Pre-Holocene) Sedimentologic and geomorphic characterization of ancient wave-dominated deltaic shorelines: Upper Cretaceous Blackhawk Formation, Book Cliffs, Utah, U.S.A. GARY J. HAMPSON AND JOHN A. HOWELL ..................................................................................................................................... 133 Integrated study of ancient delta-front deposits, using outcrop, ground-penetrating radar, and three-dimensional photorealistic data: Cretaceous Panther Tongue Sandstone, Utah, U.S.A. CORNEL OLARIU, JANOK P. BHATTACHARYA, XUEMING XU, CARLOS L.V. AIKEN, XIAOXIAN ZENG, AND GEORGE A. MCMECHAN .............................................................................................................................................................. 155 Deltas on falling-stage and lowstand shelf margins, the Eocene Central Basin of Spitsbergen: Importance of sediment supply PIRET PLINK-BJÖRKLUND AND RON STEEL ..................................................................................................................................... 179 Facies analysis of the Neogene delta of the Amur River, Sakhalin, Russian Far East: controls on sand distribution CLARE DAVIES, SARAH POYNTER, DAVID MACDONALD, RACHEL FLECKER, LARISA VORONOVA, VLADIMIR GALVERSON, PAVEL KOVTUNOVICH, LIDIYA FOT’YANOVA, AND ERIC BLANC ......................................... 207 Two deltas, two basins, one river, one sea: the modern Volga delta as an analogue of the Neogene Productive Series, South Caspian Basin S.B. KROONENBERG, M.D. SIMMONS, N.I. ALEKSEEVSKI, E. ALIYEVA, M.B. ALLEN, D.N. AYBULATOV, A. BABA-ZADEH, E.N. BADYUKOVA, C.E. DAVIES, D.J. HINDS, R.M. HOOGENDOORN, D. HUSEYNOV, B. IBRAHIMOV, P. MAMEDOV, I. OVEREEM, G.V. RUSAKOV, S. SULEYMANOVA, A.A. SVITOCH, AND S. J. VINCENT ....................................................................................................................................................... 231 Diachronous development of late Quaternary shelf-margin deltas in the northwestern Gulf of Mexico: Implications for sequence stratigraphy and deep-water reservoir occurrence JOHN B. ANDERSON .............................................................................................................................................................................. 257
Modern Deltas (Holocene) Sand-rich lithosomes of the Holocene Mississippi River delta plain MARK KULP, DUNCAN FITZGERALD, AND SHEA PENLAND ..................................................................................................... 279 The wave-dominated William River Delta, Lake Athabasca, Canada: Its morphology, radar stratigraphy, and history DERALD G. SMITH, HARRY M. JOL, NORMAN D. SMITH, RAYMOND A. KOSTASCHUK, AND CHERYL M. PEARCE ....................................................................................................................................................................... 295 Reoccupation of channel belts and its influence on alluvial architecture in the Holocene Rhine–Meuse delta, The Netherlands ESTHER STOUTHAMER ......................................................................................................................................................................... 319 3D geostatistical interpolation and geological interpretation of paleo–groundwater rise in the Holocene coastal prism in The Netherlands KIM M. COHEN ........................................................................................................................................................................................ 341 Depositional patterns in the late Holocene Po delta system ANNAMARIA CORREGGIARI, ANTONIO CATTANEO, AND FABIO TRINCARDI .................................................................. 365 River delta morphodynamics: Examples from the Danube delta LIVIU GIOSAN, JEFFREY P. DONNELLY, EMIL VESPREMEANU, AND FRANK S. BUONAIUTO .......................................... 393 The Ganges–Brahmaputra delta STEVEN A. KUEHL, MEAD A. ALLISON, STEVEN L. GOODBRED, AND HERMANN KUDRASS ....................................... 413 Sedimentation processes and asymmetric development of the Godavari delta, India K. NAGESWARA RAO, N. SADAKATA, B. HEMA MALINI, AND K. TAKAYASU ..................................................................... 435 Holocene delta evolution and depositional models of the Mekong River Delta, southern Vietnam THI KIM OANH TA, VAN LAP NGUYEN, MASAAKI TATEISHI, IWAO KOBAYASHI, AND YOSHIKI SAITO ................... 453 Sedimentology of the modern and Holocene Burdekin River delta of north Queensland, Australia— Controlled by river output, not by waves and tides CHRISTOPHER R. FIELDING, JONATHON TRUEMAN, AND JAN ALEXANDER ...................................................................... 467 Index ............................................................................................................................................................................................................ 497
