Abdallah S. Zaki

Abdallah S. Zaki

Université de Genève

H-index: 6

Europe-Switzerland

About Abdallah S. Zaki

Abdallah S. Zaki, With an exceptional h-index of 6 and a recent h-index of 6 (since 2020), a distinguished researcher at Université de Genève, specializes in the field of Geomorphology, Sedimentology, Planetary surfaces, Paleoclimatology.

His recent articles reflect a diverse array of research interests and contributions to the field:

Dendritic ridges in Antoniadi basin, Mars: Fluvial or volcanic landforms?

Prolonged Record of Hydroclimatic Changes at Antoniadi Crater, Mars

Fluvial Depositional Systems of the African Humid Period: An Analog for an Early, Wet Mars in the Eastern Sahara

Time‐probabilistic approach to the late Miocene Messinian salinity crisis: Implications for a disconnected Paratethys

Structure of channel-belt deposits within sinuous ridges on Earth and Mars

Intense precipitation during the African Humid Period inferred from east Saharan fossil rivers: Implications for human dispersal

Did increased flooding during the African Humid Period force migration of modern humans from the Nile Valley?

Global inventory of fluvial ridges on Earth and lessons applicable to Mars

Abdallah S. Zaki Information

University

Université de Genève

Position

___

Citations(all)

140

Citations(since 2020)

127

Cited By

55

hIndex(all)

6

hIndex(since 2020)

6

i10Index(all)

5

i10Index(since 2020)

5

Email

University Profile Page

Université de Genève

Abdallah S. Zaki Skills & Research Interests

Geomorphology

Sedimentology

Planetary surfaces

Paleoclimatology

Top articles of Abdallah S. Zaki

Dendritic ridges in Antoniadi basin, Mars: Fluvial or volcanic landforms?

Authors

N Mangold,A Guimpier,LL Tornabene,SJ Conway,P Fawdon,Ernst Hauber,A Noblet,AS Zaki,Antoine Pommerol,Nicolas Thomas

Journal

Icarus

Published Date

2023/12/1

Antoniadi basin displays dark-toned dendritic ridges previously interpreted as inverted fluvial channels. Detailed observations of these dark-toned ridges as well as the geological units in the central region of Antoniadi basin are provided emphasizing images from the Colour and Stereo Surface Imaging System (CaSSIS), the High Resolution Stereo Camera (HRSC) and the High Resolution Imaging Science Experiment (HiRISE) instruments. Results show that the dark-toned ridges are part of the most recent geological unit as they overlie, and thus postdate all plains of the central Antoniadi basin, which is Early Amazonian based on its crater size-frequency distribution. Our observations of the dark-toned ridges are not consistent with inverted fluvial channels: they do not widen in the expected downstream direction, they display a rubbly texture and lack layering at high resolution, and have lobes with local levees in …

Prolonged Record of Hydroclimatic Changes at Antoniadi Crater, Mars

Authors

AS Zaki,KS Edgett,M Pajola,E Kite,JM Davis,N Mangold,AS Madof,A Lucchetti,P Grindrod,CM Hughes,K Sangwan,N Thomas,M Schuster,S Gupta,G Cremonese,S Castelltort

Journal

Journal of Geophysical Research: Planets

Published Date

2023/7

The first billion years of Martian geologic history consisted of surface environments and landscapes dramatically different from those seen today, with flowing liquid water sculpting river channels and ponding to form bodies of water. However, the hydro‐climatic context, the frequency, and the duration under which these systems existed remain uncertain. Addressing these fundamental questions may improve our understanding of early Mars climate. Here, we reconstruct a long‐lived archive consisting of an array of fluvial systems inside the Antoniadi crater––one of the largest lake basins on Mars (9.58 × 104 km2). We found that the fluvial activity occurred throughout four major intermittent active intervals during the Late Noachian to Early Amazonian (∼3.7 to >2.4 Ga). This resulted in at least two major lakes, which formed during periods of markedly increased surface runoff production. The record of these four …

Fluvial Depositional Systems of the African Humid Period: An Analog for an Early, Wet Mars in the Eastern Sahara

Authors

AS Zaki,JM Davis,KS Edgett,R Giegengack,M Roige,S Conway,Mathieu Schuster,S Gupta,F Salese,KS Sangwan,AG Fairén,CM Hughes,CF Pain,S Castelltort

Journal

Journal of Geophysical Research: Planets

Published Date

2022/5

A widely hypothesized but complex transition from widespread fluvial activity to predominantly aeolian processes is inferred on Mars based on remote sensing data observations of ancient landforms. However, the lack of analysis of in situ martian fluvial deposits hinders our understanding of the flow regime nature and sustainability of the martian fluvial activity and the hunt for ancient life. Studying analogs from arid zones on Earth is fundamental to quantitatively understanding geomorphic processes and climate drivers that might have dominated during early Mars. Here we investigate the formation and preservation of fluvial depositional systems in the eastern Sahara, where the largest arid region on Earth hosts important repositories of past climatic changes. The fluvial systems are composed of well‐preserved single‐thread sinuous to branching ridges and fan‐shaped deposits interpreted as deltas. The systems' …

Time‐probabilistic approach to the late Miocene Messinian salinity crisis: Implications for a disconnected Paratethys

Authors

Sarah E Baumgardner Andrew S Madof,William BF Ryan,Claudia Bertoni,Fabien J Laugier,Abdallah S Zaki

Journal

Terra Nova

Published Date

2022/1/1

The late Miocene Messinian salinity crisis was an evaporitic episode that occurred throughout the Mediterranean; it concluded with a transition from hypersaline to fresher-water “lake sea” (Lago Mare) conditions prior to the Pliocene. Whereas numerous researchers propose that Lago Mare sediments accumulated in a Mediterranean-wide lake filled with Paratethyan waters, other workers reject this hypothesis. Here, to test this Paratethyan-overflow model, we develop a novel time-probabilistic approach to evaluate the distribution of precession-related deposits. We apply our methodology to 24 circum-Mediterranean sites, focusing on two previously untested parameters: the probability of preserving intrabasin precession cycles; and the similarities in interbasin preservation. Our results, which show an increase in preservation and similarity in successively younger cycles, display a trend opposite to what is expected from a flooded Mediterranean. Consequently, we conclude that Lago Mare accumulations were deposited in disconnected, shallow lacustrine environments, thereby casting doubt on the widely accepted Paratethyan-supply hypothesis.

Structure of channel-belt deposits within sinuous ridges on Earth and Mars

Authors

Kartikeya Singh Sangwan,Robert Barnes,Joel M Davis,Sanjeev Gupta,Abdallah S Zaki

Journal

European Planetary Science Congress

Published Date

2022/9

Structure of channel-belt deposits within sinuous ridges on Earth and Mars - NASA/ADS Now on home page ads icon ads Enable full ADS view NASA/ADS Structure of channel-belt deposits within sinuous ridges on Earth and Mars Singh Sangwan, Kartikeya ; Barnes, Robert ; Davis, Joel M. ; Gupta, Sanjeev ; Zaki, Abdallah S. Abstract IntroductionInverted channel deposits or sinuous ridges are common on the Late-Noachian Early-Hesperian terrains on Mars[1,2]. These exhumed ribbon-like, sinuous sedimentary ridges have been interpreted to be evidence of existence of liquid water on early warm and wet Mars. In addition, these ridges have been interpreted to form as either: 1) short duration single-thread fluvial systems, likely from a single flow event[3] or 2) longer duration multi-thread systems which form channel-belt structure[4]. While single-thread systems more closely preserve the actual geomorphology of the …

Intense precipitation during the African Humid Period inferred from east Saharan fossil rivers: Implications for human dispersal

Authors

Abdallah Zaki,Georgina King,Negar Haghipour,Robert Giegengack,Stephen Watkins,Sanjeev Gupta,Mathieu Schuster,Hossam Khairy,Salah Ahmed,Mostafa El-Wakil,Saleh Eltayeb,Frédéric Herman,Sébastien Castelltort

Journal

EGU General Assembly Conference Abstracts

Published Date

2022/5

During Late Quaternary time, the paleoclimate of the eastern Sahara was punctuated by multiple pluvial periods, then dramatically and cyclically transformed to hyperarid conditions, receiving less than 2 mm/yr of precipitation at present. Geologists, climate modelers, and archaeologists, therefore, have used various proxies to reconstruct past climates during that time, a crucial period for human habitation and migration. These reconstructions, however, lack the precipitation pattern during those pluvial periods, which represents a significant control on weighing the hypotheses of human migrations and occupations. Here we reconstruct the chronology and paleohydrology of a set of fossil rivers expressed by ridges in the modern landscape due to differential erosion. Our 14C and Optically Stimulated Luminescence (OSL) ages of sediments preserved in these ancient rivers cluster within the last African Humid Period …

Did increased flooding during the African Humid Period force migration of modern humans from the Nile Valley?

Authors

Abdallah S Zaki,Georgina E King,Negar Haghipour,Robert Giegengack,Stephen E Watkins,Sanjeev Gupta,Mathieu Schuster,Hossam Khairy,Salah Ahmed,Mostafa El-Wakil,Saleh A Eltayeb,Frédéric Herman,Sébastien Castelltort

Published Date

2021/11/15

During the Quaternary period, the eastern Sahara's hydroclimate oscillated between wet and dry intervals. These oscillations caused drastic changes in precipitation rates, often associated with ancient human migrations. In particular, significant migration of riparian populations from the Nile Valley to the west and northwestward of the Sahara occurred during the African Humid Period (AHP), an episode of increased monsoons, which characterized North Africa in response to increasing insolation. Several fossil rivers, now preserved as ridges throughout southern Egypt due to their floodplains' deflation, contain archeological artifacts and thus represent a potentially important record of fluvial activity during this episode of past human dynamics and environmental change. Here we present 14C and Optically Stimulated Luminescence (OSL) ages of sediments preserved in these palaeorivers, which cluster within the …

Global inventory of fluvial ridges on Earth and lessons applicable to Mars

Authors

Abdallah S Zaki,Colin F Pain,Kenneth S Edgett,Sébastien Castelltort

Published Date

2021/5/1

Orbiting and landed spacecrafts have provided vast amounts of data on fluvial and fluvial-related landforms and sediments on Mars. One variant of these landforms consists of ridges interpreted to be remnants of ancient fluvial activity, observed at thousands of Martian locales, suggesting extensive precipitation and runoff on early Mars. The importance of these ridges increased after the selection of the Jezero crater and the Oxia Planum landing sites for NASA's Perseverance and ESA's Rosalind Franklin rovers because these locations preserve fluvial sediments in ancient, lithified deltaic landforms. To further understand Martian fluvial ridges, this contribution presents an inventory of 104 sites of fluvial ridges on Earth, offering Upper Ordovician to late Holocene examples that are analogous to their Martian counterparts. The Earth global data set provides environmental contexts for the formation mechanisms and …

Upstream and downstream controls on aggradation in a small-scale physical river model: implications for fluvial stratigraphy

Authors

Stephen Watkins,Nikhil Sharma,Luis Valero,Maxime Tremblin,Abdallah Zaki,Frédéric Arlaud,Guy Simpson,Laure Guerit,Sebastien Castelltort

Journal

AGU Fall Meeting Abstracts

Published Date

2020/12

Fluvial stratigraphy has the potential to record changes in accommodation generated by both downstream drivers (ie sea-level change) and-or upstream drivers (ie water and/or sediment discharge changes). Hence, the hypothesis is that changes in either of these drivers can potentially cause rivers to respond and adjust to a new equilibrium river profile by aggradation or degradation. Fluvial stratigraphy, therefore, remains a major archive of past environmental changes. However, we still lack the ability to differentiate the manifestation of upstream and downstream driven changes when faced with fluvial stratigraphic successions. Here we explore this problem using physical modelling, which has the advantage of being able to independently control both upstream and downstream parameters.

How do river channels aggrade? An investigation into the importance of upstream drivers (water discharge and sediment supply) on sediment aggradation using analogue modelling

Authors

Stephen E Watkins,Nikhil Sharma,Luis Valero,Maxime Tremblin,Abdallah S Zaki,Frédéric Arlaud,Guy Simpson,Sébastien Castelltort

Journal

EGU General Assembly Conference Abstracts

Published Date

2020/5

Stratigraphic architecture of fluvial deposits is often interpreted as a record of changes in accommodation created by absolute sea-level change, subsidence, or a combination of both (downstream drivers). An increase or decrease in accommodation causes the fluvial system to respond by either aggrading or degrading to a new equilibrium slope. However, in recent years the role of upstream drivers, such as water discharge and sediment supply (volume and grain-size distribution), in controlling equilibrium slopes has gained more importance, however we still lack significant understanding of these upstream processes. It is important to be able to differentiate between stratigraphy influenced by upstream and downstream drivers in the field because fluvial deposits represent an important archive of environmental changes. Traditionally, downstream drivers are often invoked to explain past accommodation changes …

New palaeoclimate record from ancient river channels in the eastern Sahara: Implications for climate impact on human dispersals during the late Quaternary

Authors

Abdallah S Zaki,Georgina E King,Negar Haghipour,Frédéric Herman,Robert Giegengack,Mathieu Schuster,Sanjeev Gupta,Stephen E Watkins,Hossam Khairy,Salah Ahmed,Saleh A Eltayeb,Mostafa El-wakil,Sébastien Castelltort

Journal

EGU General Assembly Conference Abstracts

Published Date

2020/5

Throughout the last 65,000 years, there have been several brief periods of increased temperatures and precipitation over the eastern Sahara. These periods have been constrained by numerous proxies including: palaeodischarge and sediment-load estimates of the Nile River, cave speleothems, dust fluxes, fossil groundwater, marine sediments, and reconstructed palaeolake level fluctuations. These climate disturbances are widely considered to have affected both the migration patterns of anatomically modern humans and Holocene human settlements. However, these proxies can not be directly translated into precipitation intensity which would have had a profound impact on human activities, as intense precipitation events would make settlements next to rivers hazardous places to live. Here we reconstruct the paleoenvironmental conditions of six palaeoriver channel systems preserved over a ca 40'000 km2 …

Global inventories of inverted stream channels on Earth and Mars

Authors

Abdallah Zaki,Colin Pain,Kenneth S Edgett,Sebastien Castelltort

Published Date

2020/3

Data from orbiting and landed spacecraft have provided vast amounts of information regarding fluvial and fluvial-related landforms and sediments on Mars. One variant of these landforms are sinuous ridges that have been interpreted to be remnant evidence for ancient fluvial activity, observed at hundreds of martian locales. In order to further understanding of these martian landforms, this paper inventories the 107 known and unknown inverted channel sites on Earth; these offer 114 different examples that consist of materials ranging in age from Upper Ordovician to late Holocene. These examples record several climatic events from the Upper Ordovician glaciation to late Quaternary climate oscillation. These Earth examples include inverted channels in deltaic and alluvial fan sediment, providing new analogs to their martian counterparts. This global dataset provides environmental context regarding the formation mechanisms and conditions that accompanied channel formation and inversion. There are five documented processes by which channel sediment and valley fill become consolidated and inverted after adjacent floodplain sediments are eroded away: (1) channel fill cementation during near-surface, early diagenesis; (2) channel fill lithification during burial diagenesis in the subsurface; (3) filling of a channel or valley by extrusive volcanism (lavas, tuffs); (4) channel surface armouring of coarse clasts by aeolian and fluvial processes; (5) compaction of bank-forming peat, which can lead to early inversion without removal of floodplain material. On Earth, early diagenesis (shallow surficial cementation) dominates among inverted fluvial …

Inverted channels in the Eastern Sahara—distribution, formation, and interpretation to enable reconstruction of paleodrainage networks

Authors

Abdallah S Zaki,Robert Giegengack,Sébastien Castelltort

Journal

Palaeohydrology: Traces, Tracks and Trails of Extreme Events

Published Date

2020

During the Cenozoic Era, the Egyptian Sahara was the site of fluvial activity in a succession of at least three main drainage systems, including the Gilf System (40–16 Ma ago), the Qena System (24–6 Ma ago), and the Nile (30 Ma ago to present). These systems developed as a response to wet conditions, the dramatic events of tectonic activity in the Red Sea Region and southwestern Egypt, and changes of sea level in the Tethys Sea in Late Eocene time to sea-level rise in Late Pleistocene time. The modern Nile consists of captured components of ancestral Nile segments. Representatives of those Nile ancestors and lost tributaries of the Nile have been buried beneath dune fields and sand seas, or have been eroded by wind deflation to be topographically inverted. In this chapter, we present the distribution of inverted river channels in the Egyptian Sahara , and a description of the mechanisms that led …

Reconstructing the fluvial history of Antoniadi crater: Evidence for Noachian and Amazonian stream networks on Mars

Authors

Abdallah Zaki,Kenneth S Edgett,Sanjeev Gupta,Maurizio Pajola,Joel Davis,Cory M Hughes,Stephen Watkins,Luis Valero,Peter M Grindrod,Nicolas Thomas,Gabriele Cremonese,Sebastien Castelltort

Journal

AGU Fall Meeting Abstracts

Published Date

2020/12

Hundreds of candidate paleolake sites have been recognized from orbiting and landing Mars missions. One of these potential paleolake sites is the 400-km diameter impact crater, Antoniadi. It might have hosted an open-basin lake fed by valley networks from the north and east showing a complexity of fluvial activity during the early climate of Mars. We use Context Camera (CTX), High-Resolution Imaging Science Experiment (HiRISE), Color and Stereo Surface Imaging System (CaSSIS), and Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) data to investigate landforms in Antoniadi that record a range of paleohydrological processes. Antoniadi exhibits diverse landforms suggesting fluvial erosion by surface and subsurface hydrology, including valley networks, fan-shaped sediment deposits, and short and stubby branched ridges that record a previous fluvial system. One of the fans consists of …

See List of Professors in Abdallah S. Zaki University(Université de Genève)

Abdallah S. Zaki FAQs

What is Abdallah S. Zaki's h-index at Université de Genève?

The h-index of Abdallah S. Zaki has been 6 since 2020 and 6 in total.

What are Abdallah S. Zaki's top articles?

The articles with the titles of

Dendritic ridges in Antoniadi basin, Mars: Fluvial or volcanic landforms?

Prolonged Record of Hydroclimatic Changes at Antoniadi Crater, Mars

Fluvial Depositional Systems of the African Humid Period: An Analog for an Early, Wet Mars in the Eastern Sahara

Time‐probabilistic approach to the late Miocene Messinian salinity crisis: Implications for a disconnected Paratethys

Structure of channel-belt deposits within sinuous ridges on Earth and Mars

Intense precipitation during the African Humid Period inferred from east Saharan fossil rivers: Implications for human dispersal

Did increased flooding during the African Humid Period force migration of modern humans from the Nile Valley?

Global inventory of fluvial ridges on Earth and lessons applicable to Mars

...

are the top articles of Abdallah S. Zaki at Université de Genève.

What are Abdallah S. Zaki's research interests?

The research interests of Abdallah S. Zaki are: Geomorphology, Sedimentology, Planetary surfaces, Paleoclimatology

What is Abdallah S. Zaki's total number of citations?

Abdallah S. Zaki has 140 citations in total.

What are the co-authors of Abdallah S. Zaki?

The co-authors of Abdallah S. Zaki are Mangold Nicolas, Frédéric Herman, Edwin Kite, Sebastien Castelltort, Georgina King, Cory M. Hughes.

    Co-Authors

    H-index: 87
    Mangold Nicolas

    Mangold Nicolas

    Université de Nantes

    H-index: 43
    Frédéric Herman

    Frédéric Herman

    Université de Lausanne

    H-index: 34
    Edwin Kite

    Edwin Kite

    University of Chicago

    H-index: 29
    Sebastien Castelltort

    Sebastien Castelltort

    Université de Genève

    H-index: 22
    Georgina King

    Georgina King

    Université de Lausanne

    H-index: 7
    Cory M. Hughes

    Cory M. Hughes

    University of Arkansas

    academic-engine

    Useful Links