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The new knowledge is written on sedimentary rocks——a comment on Shanmugam’s paper “the hyperpycnite problem”

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Journal of Palaeogeography 2019年第3期8卷 306-313页

作者： Carlos Zavala Departamento de Geología Universidad Nacional del Sur GCS Argentina SRL

In a recent contribution G. Shanmugam (2018) discusses and neglects the importance of hyperpycnal flows and hyperpycnites for the understanding of some sediment gravity flow deposits. For him, the hyperpycnal flow paradigm is strictly based on experimental and theoretical concepts, without the supporting empirical data from modern depositional systems. In this discussion I will demonstrate that G. Shanmugam overlooks growing evidences that support the importance of hyperpycnal flows in the accumulation of a huge volume of fossil clastic sediments. Sustained hyperpycnal flows also provide a rational explanation for the origin of well sorted fine-grained massive sandstones with floating clasts, a deposit often wrongly related to sandy debris flows.

关键词： hyperpycnites Turbidites Sediment gravity flows

Hyperpycnal (over density) flows and deposits

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Journal of Palaeogeography 2020年第3期9卷 267-287页

作者： Carlos Zavala Departamento de Geologia Universidad Nacional del SurSan Juan 6708000 Bahia BlancaArgentina GCS Argentina 5RL Molina Campos 1508000 Bahia BlancaArgentina

A hyperpycnal flow forms when a relatively dense land-derived gravity flow enters into a marine or lacustrine water reservoir. As a consequence of its excess of density, the incoming flow plunges in coastal areas, generating a highly dynamic and often long-lived dense underflow. Depending on the characteristics of the parent flow(flow duration and flow rheology) and basin salinity, the resulting deposits(hyperpycnites) can be very *** to flow duration, land-derived gravity flows can be classified into short-lived or long-lived flows. Shortlived gravity flows last for minutes or hours, and are mostly related to small mountainous river discharges, alluvial fans, collapse of natural dams, landslides, volcanic eruptions, j?kulhlaups, etc. Long-lived gravity flows last for days,weeks or even months, and are mostly associated with medium-to large-size river *** the rheology of the incoming flow, hyperpycnal flows can be initiated by non-Newtonian(cohesive debris flows), Newtonian supercritical(lahars, hyperconcentrated flows, and concentrated flows) or Newtonian subcritical flows(pebbly, sandy or muddy sediment-laden turbulent flows). Once plunged, non-Newtonian and Newtonian supercritical flows require steep slopes to accelerate, allow the incorporation of ambient water and develop flow transformations in order to evolve into a turbidity current and travel further basinward. Their resulting deposits are difficult to differentiate from those related to intrabasinal turbidites. On the contrary, long-lived Newtonian subcritical flows are capable of transferring huge volumes of sediment, freshwater and organic matter far from the coast even along gentle or flat slopes. In marine settings, the buoyant effect of interstitial freshwater in pebbly and sandy hyperpycnal flows can result in lofting due to flow density reversal. Since the excess of density in muddy hyperpycnal flows is provided by silt-clay sediments in turbulent suspension, lofting

关键词： Hyperpycnal flows hyperpycnites Turbidites Sediment gravity flows

The hyperpycnite problem

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Journal of Palaeogeography 2018年第3期7卷 197-238页

作者： G.Shanmugam Department of Earth and Environmental Sciences The University of Texas at Arlington

Sedimentologic, oceanographic, and hydraulic engineering publications on hyperpycnal flows claim that （1） river flows transform into turbidity currents at plunge points near the shoreline, （2） hyperpycnal flows have the power to erode the seafloor and cause submarine canyons, and, （3） hyperpycnal flows are efficient in transporting sand across the shelf and can deliver sediments into the deep sea for developing submarine fans. Importantly, these claims do have economic implications for the petroleum industry for predicting sandy reservoirs in deep-water petroleum exploration. However, these claims are based strictly on experimental or theoretical basis, without the supporting empirical data from modern depositional systems. Therefore, the primary purpose of this article is to rigorously evaluate the merits of these claims. A global evaluation of density plumes, based on 26 case studies （e.g., Yellow River, Yangtze River, Copper River, Hugli River （Ganges）, Guadalquivir River, Rio de ]a Plata Estuary, Zambezi River, among others）, suggests a complex variability in nature. Real-world examples show that density plumes （1） occur in six different environments （i.e., marine, lacustrine, estuarine, lagoon, bay, and reef）; （2） are composed of six different compositional materials （e.g., siliciclastic, calciclastic, planktonic, etc.）; （3） derive material from 11 different sources （e.g., river flood, tidal estuary, subglacial, etc.）; （4） are subjected to 15 different external controls （e.g., tidal shear fronts, ocean currents, cyclones, tsunamis, etc.）; and, （5） exhibit 24 configurations （e.g., lobate, coalescing, linear, swirly, U-Turn, anastomosing, etc.）. Major problem areas are：（1） There are at least 16 types of hyperpycnal flows （e.g., density flow, underflow, high-density hyperpycnal plume, high-turbid mass flow, tide-modulated hyperpycnal flow, cyclone-induced hyperpycnal turbidity current, multi-layer hyperpycnal flows, etc.）, without an underpinning principle of flu

关键词： Density plumes Facies model hyperpycnites Submarine fans Tidal shear fronts Ocean currents Turbiditycurrents Yellow River Yangtze River

Reply to discussions by Zavala(2019) and by Van Loon, Hüeneke, and Mulder(2019)on Shanmugam, G.(2018, Journal of Palaeogeography, 7(3): 197–238): ‘the hyperpycnite problem’

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Journal of Palaeogeography 2019年第4期8卷 408-421页

作者： G.Shanmugam Department of Earth and Environmental Sciences The University of Texas at Arlington

In this reply,I respond to 18 issues associated with comments made by Zavala(e.g.,inverse-to normally-graded sequence,origin of massive sands,experimental sandy debris flows,tidal rhythmites,facies models,etc.),and 10 issues associated with comments made by Van Loon et al.(e.g.,16 types of hyperpycnal flows,anthropogenic hyperpycnal flow,etc.).

关键词： Hyperpycnal flows hyperpycnites Sandy debris flows Turbidity currents

Deltas:a new classification expanding Bates's concepts

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Journal of Palaeogeography 2021年第3期10卷 341-355页

作者： Carlos Zavala Mariano Arcuri Mariano Di Meglio Agustin Zorzano German Otharan Ainara Irastorza Antonela Torresi Dpto.de Geologia Universidad Nacional del Sur(UNS)Bahia BlancaArgentina GCS Argentina SRL Molina Campos 1508000 Bahia BlancaArgentina Consejo Nacional de Investigaciones Científicas y Tecnicas (CONICET)Buenos AiresArgentina

Deltas constitute complex depositional systems formed when a land-derived gravity-flow(carrying water and sediments) discharges into a marine or lacustrine standing body of water. However, the complexity of deltaic sedimentary environments has been oversimplified by geoscientists over the years, considering just littoral deltas as the unique possible type of delta in natural systems. Nevertheless, a rational analysis suggests that deltas can be much more complex. In fact, the characteristics of deltaic deposits will depend on a complex interplay between the bulk density of the incoming flow and the salinity of the receiving water body. This paper explores the natural conditions of deltaic sedimentation according to different density contrasts. The rational analysis of deltaic systems allows to recognize three main fields for deltaic sedimentation, corresponding to(1) hypopycnal(2) homopycnal and(3) hyperpycnal delta settings. The hypopycnal delta field represents the situation when the bulk density of the incoming flow is lower than the density of the water in the basin. According to the salinity of the receiving water body, three different types of hypopycnal littoral deltas are recognized: hypersaline littoral deltas(HSLD), marine littoral deltas(MLD), and brackish littoral deltas(BLD). The basin salinity will determine the capacity of the delta for producing effective buoyant plumes, and consequently the characteristics and extension of prodelta *** littoral deltas(HOLD) form when the density of the incoming flow is roughly similar to the density of the water in the receiving basin. This situation is typical of clean bedload-dominated rivers entering freshwater lakes. Delta front deposits are dominated by sediment avalanches. Typical fallout prodelta deposits are absent or poorly developed since no buoyant plumes are generated. Hyperpycnal deltas form when the bulk density of the incoming flow is higher than the density of the water in the receivi

关键词： Deltas Hyperpycnal flows Homopycnal flows Hypopycnal flows hyperpycnites Turbidites Sediment gravity flows Gravity flows

A remarkable decade of learning and sharing knowledge through the Journal of Palaeogeography(JoP)(2014-2024):Reminiscences from an Associate Editor-in-Chief

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Journal of Palaeogeography 2024年第4期13卷 1029-1040页

作者： G.Shanmugam Department of Earth and Environmental Sciences The University of Texas at ArlingtonArlingtonTX 76019USA

In this editorial,an Associate Editor-in-Chief of the Journal of Palaeogeography(JoP)reminisces his publication experience in JoP during the period 2014-2024.1)During a period of nine years,he contributed eight review articles,three discussions,two replies,one book review,one glossary,and one tribute to the first Editor-in-Chief ***-Zhao *** contributions totaled 534 printed pages.2)His contributions examined 19 different domains,such as landslides,submarine fans,seismites,SSDS,hyperpycnites,rivers,etc.3)His contributions coincided with the formative years of JoP.4)The impact of his articles is evident from the Stats published by *** example,his review article“The Landslide Problem”has reached11,611 Reads and 186 Citations after nine years of publication in 2015.5)In 2023,the CNKI(China National Knowledge Infrastructure)recognized his article“Submarine fans:a critical retrospective(1950-2015)”as the Top-1%most-highly cited publications in the Journal of Palaeogeography published during a 10-year survey period:2012-2022.6)He was inducted as a Founding Member of the International Society of Palaeogeography(ISP)at Changping District of China University of Petroleum(Beijing),Beijing on July 16,2022.7)His JoP editorship during the past 10 years has been the most challenging,inspiring,and rewarding experience of his global scientific journey spanning over six decades(1962-2024).

关键词： Journal of Palaeogeography Associate Editor-in-Chief Editorial Landslides Submarine fans Seismites SSDS hyperpycnites Zeng-Zhao Feng

Shallow-Water Origin of a Devonian Black Shale, Cleveland Shale Member (Ohio Shale), Northeastern Ohio, USA

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Open Journal of Geology 2014年第12期4卷 636-653页

作者： Saeed Alshahrani James E. Evans Department of Geology Bowling Green State University Bowling Green OH USA EXPEC Advanced Research Center Saudi ARAMCO Dhahran Saudi Arabia

Black shales are usually interpreted to require anoxic bottom waters and deeper water sedimentation. There has long been a debate about whether the Devonian Cleveland Shale Member of the Ohio Shale (CSM) was deposited in shallow- or deep-water depositional environments. This study looked at the CSM at 3 stratigraphic sections and 5 well cores in northeastern Ohio. The CSM mostly consists of sapropelite (interbedded carbonaceous black mudstones and gray calcareous claystones). The black and gray “shales” are rhythmically bedded at micro- (hyperpycnites. Individual tempestites and turbidites are laterally continuous?≥35 km, while hyperpycnites are too thin (hyperpycnites (density underflows from river discharge) consist of inverse-to-normal graded sandy or silty microlaminae that have been studied primarily by using petrography and SEM. Condensed sections in the CSM are probable firmgrounds with carbonate concretions, and indicate intervals of low sedimentation rates. The evidence shows that the CSM depositional environment was receiving siliciclastics from the northeast (e.g., Catskill delta), and that the coarser-grained clastic sediment was primarily transported as density underflows (turbidites and hyperpycnites). However, signific

关键词： Black Shales Tempestites hyperpycnites Devonian Appalachian Basin Catskill Delta