Submerged landscapes of the eastern Adriatic – from the river across the lake all the way to the sea

2021 ◽  
Author(s):  
Slobodan Miko ◽  
Keyword(s):  
Sea Level ◽  
Environmental Changes ◽  
Late Quaternary ◽  
River Estuary ◽  
Integrated System ◽  
Submarine Channels ◽  
Side Scan Sonar ◽  
Sedimentary Sequences ◽  
Marine Sedimentation ◽  
Geophysical Surveys

<p>Submerged paleolandscapes constitute records of long-term paleoenvironmental change, climate, and sea level. To date, there is a very limited knowledge concerning the submerged karst paleolandscapes of the eastern Adriatic coast and the Late Quaternary sedimentary sequences along the eastern part of the Mid Adriatic Deep (MAD). We aim to improve this through the project “Sediments between source and sink during a Late Quaternary eustatic cycle: The Krka and the Mid Adriatic Deep System” (QMAD). The QMAD project supports multidisciplinary research by application of the high-resolution geophysical surveys (multibeam, side-scan sonar and sub-bottom profiler), in combination with sedimentological, petrophysical, geochemical (trace elements and isotopes), micropaleontological (ostracod and foraminifera), mineralogical and aDNA techniques. This suite of analyses will enable tracking of the paleoenvironmental evolution from fluvial/lake to deeper marine environments, on a short transect less than 100 km in length (Lake Prokljan in the Krka River estuary to the eastern part of MAD). The submerged Late Pleistocene and Holocene environments that occur include isolation basins, lagoons, deltas, estuaries, submarine channels and shelf. The continuous marine sedimentation during the Late Quaternary is investigated in the MAD. In the case of the central part of the eastern side of the Adriatic Sea (Krka catchment - MAD) these different environments compose an integrated system; thus, they can’t be analysed separately. The main goals of this project fill the existing gaps in understanding of the climatic and environmental changes, including sea-level related landscape changes and their interplay during the Late Quaternary eustatic cycle. More data on the Pleistocene environments, especially from the region of Krka estuary that was land during the Last Glacial Maximum (LGM), will complete the picture of the evolution and environmental adaptation of Paleolithic humans and their relationship with vegetation changes. Attention is also paid to potential anthropogenic environments, recent sedimentation rates, landscape features and artefacts. All results of the multi-proxy approach applied in this project will eventually be merged into a comprehensive Late Quaternary paleoenvironmental and paleoclimatic reconstruction of the eastern Adriatic landscapes that contribute to the understanding of these changes in the Mediterranean region.</p>

scholarly journals Geomorphology of Canyon Outlets in Zrmanja River Estuary and Its Effect on the Holocene Flooding of Semi-enclosed Basins (the Novigrad and Karin Seas, Eastern Adriatic)

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2807
Author(s):  
Ozren Hasan ◽  
Slobodan Miko ◽  
Dea Brunović ◽  
George Papatheodorou ◽  
Dimitris Christodolou ◽  
...  
Keyword(s):  
High Resolution ◽  
Sea Level Rise ◽  
Sea Level ◽  
Geophysical Methods ◽  
River Estuary ◽  
Side Scan Sonar ◽  
The Holocene ◽  
Karst Environment ◽  
Gis Environment ◽  
Holocene Sea Level

Detailed multi-beam bathymetry, sub-bottom acoustic, and side-scan sonar observations of submerged canyons with tufa barriers were used to characterize the Zrmanja River karst estuary on the eastern Adriatic coast, Croatia. This unique karst environment consists of two submerged karst basins (Novigrad Sea and Karin Sea) that are connected with river canyons named Novsko Ždrilo and Karinsko Ždrilo. The combined use of high-resolution geophysical data with legacy topography and bathymetry data in a GIS environment allowed for the description and interpretation of this geomorphological setting in relation to the Holocene sea-level rise. The tufa barriers had a predominant influence on the Holocene flooding dynamics of the canyons and karst basins. Here, we describe the possible river pathways from the basins during the lowstand and the formation of a lengthening estuary during the Holocene sea-level rise. Based on the analyzed morphologies and the relative sea-level curve for the Adriatic Sea, the flooding of the Novsko Ždrilo occurred 9200 years before present (BP) and Karinsko Ždrilo was flooded after 8400 years BP. The combination of high-resolution geophysical methods gave an accurate representation of the karst estuarine seafloor and the flooding of semi-isolated basins due to sea-level rise.

scholarly journals Holocene sea level and environmental change at the southern Cape – an 8.5 kyr multi-proxy paleoclimate record from lake Voёlvlei, South Africa

2020 ◽  
Author(s):  
Paul Strobel ◽  
Marcel Bliedtner ◽  
Andrew S. Carr ◽  
Peter Frenzel ◽  
Björn Klaes ◽  
...  
Keyword(s):  
South Africa ◽  
Sea Level ◽  
Coastal Wetland ◽  
Environmental Changes ◽  
Late Quaternary ◽  
Regional Studies ◽  
Sea Level Changes ◽  
Cape Coast ◽  
Allochthonous Input ◽  
Elemental Analyses

Abstract. South Africa is a key region for paleoclimate studies reconstructing and understanding past changes in atmospheric circulation, i.e., temperate Westerlies and tropical Easterlies. However, due to the scarcity of natural archives, the environmental evolution during the late Quaternary remains highly debated. Many archives that are available are peri-coastal lakes and wetlands and sea level changes during the Holocene often overprinted the paleoenvironmental signals in these archives. This study presents a new record from the coastal wetland Voёlvlei, which is an intermittent lake situated in the year-round rainfall zone (YRZ) of South Africa at the southern Cape coast. It presents an ideal archive to investigate both sea level and environmental changes. A 13 m-long sediment core was retrieved from Voёlvlei and analysed using a multi-proxy approach. The chronology reveals a basal age of 8,440+200/−250 cal BP. Paleoecological and elemental analyses indicate marine intrusions from 8,440 to 7,000 cal BP with a salinity optimum at 7,030+150/−190 cal BP. Since 6,000 cal BP, silting up has been causing an intermittent freshwater lake. Inferred from changes in allochthonous input, δ13Cn-alkane and δ2Hn-alkane increasing moisture is observed from 8,440+200/−250 cal BP. The δ2Hn-alkane record provides new evidence in contribution of different precipitation sources throughout the record with contributions from both Westerlies and Easterlies from 8,440 to 7,070 cal BP. Westerlies dominate from 7,070 to 6,420 cal BP followed by a distinct shift to an Easterly-dominance at 6,420 cal BP. An overall trend to a Westerly-lasting until 2,060 cal BP is followed by a trend towards an Easterlies-dominance, but both phases show several climatic spikes. Those spikes are also evident in other regional studies highlighting that the source and seasonality of precipitation has a mayor role for the hydrological balance. By comparing the Voёlvlei record with other regional studies, a similar trend in the overall moisture evolution along the southern Cape coast is inferred during the past 8.500 yrs.

Seabed geomorphology of the Prokljan Lake – a Krka River estuary on the eastern Adriatic coast (Dalmatia)

2021 ◽  
Author(s):  
Ozren Hasan ◽  
Slobodan Miko ◽  
Dea Brunović ◽  
Natalia Šenolt ◽  
Martina Šparica Miko ◽  
...  
Keyword(s):  
Grain Size ◽  
Sea Level Rise ◽  
Sea Level ◽  
Late Quaternary ◽  
River Estuary ◽  
Lake Area ◽  
Fine Silt ◽  
The Holocene ◽  
Sediment Size ◽  
Adriatic Coast

<p>Vast areas of the shallow Adriatic shelf were exposed at the time of the Last Glacial Maximum lowstand. This enabled formation of lakes, river valleys and river floodplains that were submerged during the Holocene transgression. Here we present a study of the karst estuary of the Krka River located in central Dalmatia on the eastern Adriatic coast. The Krka River creates a 23 km long estuary extending north from the Šibenik Channel, over the Prokljan Lake, up to the tufa waterfall Skradinski buk. We used high resolution acoustic methods including sub-bottom profiler (SBP) coupled with multibeam echo sounder (MBES) (MBES bathymetry and MBES backscatter) and side-scan sonar (SSS) to investigate the submerged karst river valley and lake system that existed before the Holocene relative sea level rise. A total of 70 km of SBP profiles and a point cloud of 241 991 638 points in the area of 6.2 km<sup>2</sup> were collected during the surveys. Water depth ranges from 5 m b.s.l. in the most northern part of the study area, to 25 m b.s.l. in the southern part of the Prokljan lake.</p><p>To create a better geomorphological and geological classifications of the seabed, we made a network of 36 ground truthing stations where we sampled sediments with Van Veen grab sampler and obtained underwater images. Sediment samples were analyzed for grain size, bulk density, carbon and nitrogen concentrations, as well as mineralogical XRD analysis and magnetic susceptibility. We combined gathered data with GIS classification tools to create accurate seabed maps of the area. Our results also showed that well-defined submerged river canyon in the Prokljan Lake area was filled with three sedimentary units: fluvial, brackish and marine. Quaternary sediment thickness is up to 15 m. Seabed geomorphology of the investigated area is characterized by many submerged tufa barriers. They are similar to present barriers upstream of the Skradinski buk waterfall. These unique karst geomorphological features, that grow as algae and mosses are encrusted by carbonate, enabled formation of lakes, as well as prevented a marine flooding during the Holocene sea-level rise. The depth of each barrier (4.5 to 12 m b.s.l.), in connection to the onset of marine sedimentation within the estuary, can be used as an indicator of sea level. Barriers are emphasized on the MBES backscatter data as strong reflectors. Grain size of sampled sediments ranges from poorly sorted sand and gravel on underwater barriers to fine silt sediments in the deeper parts of Prokljan Lake. Larger sediment size on barriers is caused by tufa debris while fine silt is sedimented in the deeper parts of the basin. Grain size results vary for different geomorphological provinces, allowing for a more precise (GIS) classification and description of the seabed.</p><p>This work was supported by the Croatian Science Foundation Project “Sediments between source and sink during a late Quaternary eustatic cycle: the Krka River and the Mid Adriatic Deep System” (QMAD) (HRZZ IP-04-2019-8505).</p>

Detailed Documentation of a Holocene Sea-Level Record in the Perth Region, Southern Western Australia

1986 ◽  
Vol 26 (3) ◽  
pp. 299-308 ◽  
Author(s):  
D. J. Searle ◽  
P. J. Woods
Keyword(s):  
Sea Level ◽  
Western Australia ◽  
Late Quaternary ◽  
Sedimentary Sequences ◽  
Precise Understanding ◽  
Level Data ◽  
Analogous Data ◽  
Fixed Reference ◽  
Comparable Accuracy ◽  
Detailed Record

Holocene prograded coastal sequences at Becher/Rockingham, southern Western Australia, contain a detailed record of sea level over the last 6400 yr. Radiocarbon dating and use of a distinct stratigraphic indicator as a sea-level marker permit reconstruction of sea-level history and suggest that the sea was at least 2.5 m above present datum about 6400 yr B.P. before falling to its present level. No evidence was found for eustatic fluctuations of the scale proposed by R. W. Fairbridge [1961,in“Physics and Chemistry of the Earth” (L. H. Ahrens, F. Press, K. Rankema, and S. K. Runcorn, Eds.), Vol. 4, pp. 99–185, Pergamon, Oxford]. The sea-level record preserved on this coast can be explained by hydro-isostasy, tectonism, or eustasy, acting individually or in concert. Without a fixed reference point or analogous data from other locations, a firm conclusion on which mechanism(s) has(have) operated could not be reached. Published sea-level data from this and other coasts are often insufficiently detailed to compare with this study. Application of the techniques of this study to analogous sedimentary sequences elsewhere will provide data of comparable accuracy that would contribute to a more precise understanding of relative sea-level movements in the late Quaternary.

scholarly journals Investigating the Norse Harbour of Igaliku (Southern Greenland) Using an Integrated System of Side-Scan Sonar and High-Resolution Reflection Seismics

2019 ◽  
Vol 11 (16) ◽  
pp. 1889 ◽  
Author(s):  
Dennis Wilken ◽  
Tina Wunderlich ◽  
Peter Feldens ◽  
Joris Coolen ◽  
John Preston ◽  
...  
Keyword(s):  
High Resolution ◽  
Sea Level ◽  
Integrated System ◽  
Small Island ◽  
Differential Gps ◽  
Side Scan Sonar ◽  
Reflection Seismic ◽  
Reflection Seismics ◽  
Survey System ◽  
Fertile Land

This study presents the results of a marine geophysical survey performed in the Igaliku fjord in southern Greenland in order to understand the harbour setting of the former Norse settlement Garðar (modern Igaliku). The aims of the survey were (a) to reconstruct the former coastline during the first centuries of the Norse settlement period (c. 11/12th centuries) and (b) to search for archaeological remains on the seabed connected to maritime traffic and trade. In order to approach these goals, we used an integrated marine survey system consisting of a side-scan sonar and a reflection seismic system. The system was designed for lightweight transport, allowing measurements in areas that are logistically difficult to access. The side-scan sonar data revealed no remains of clear archaeological origin. Bathymetric data from seismic seabed reflection and additional Differential GPS height measurements yielded a high-resolution bathymetric map. Based on estimates of Holocene relative sea level change, our bathymetry model was used to reconstruct the shift of the high and low-water line since the early Norse period. The reconstructed coastline shows that a small island, which hosts the ruins of a tentative Norse warehouse at the mouth of the present harbour, was connected to the shore at low tide during the early Norse period. In addition, reflection seismics and side-scan sonar images reveal a sheltered inlet with steep slopes on one side of the island, which may have functioned as a landing bridge used to load ships. We also show that the loss of fertile land due to sea level rise until the end of the Norse settlement was insignificant compared to the available fertile land in the Igaliku fjord and is thus not the reason for the collapse of the colony.

scholarly journals Late Quaternary sea level, isostatic response, and sediment dispersal along the Queen Charlotte fault

Geosphere ◽  
2021 ◽  
Author(s):  
J. Vaughn Barrie ◽  
H. Gary Greene ◽  
Kim W. Conway ◽  
Daniel S. Brothers
Keyword(s):  
Sea Level ◽  
Late Quaternary ◽  
Shelf Break ◽  
Fault System ◽  
Haida Gwaii ◽  
Storm Activity ◽  
Submarine Channels ◽  
Southeast Alaska ◽  
Short Period ◽  
Level Lowering

The active Pacific margin of the Haida Gwaii and southeast Alaska has been subject to vigorous storm activity, dramatic sea-level change, and active tectonism since glacial times. Glaciation was minimal along the western shelf margin, except for large ice streams that formed glacial valleys to the shelf break between the major islands of southeast Alaska and Haida Gwaii. Upon deglaciation, sediment discharge was extensive, but it terminated quickly due to rapid glacial retreat and sea-level lowering with the development of a glacio-iso­static forebulge, coupled with eustatic lowering. Glacial sedimentation offshore ended soon after 15.0 ka. The shelf became emergent, with sea level lowering by, and possibly greater than, 175 m. The rapid transgression that followed began sometime before 12.7 ka off Haida Gwaii and 12.0 ka off southeast Alaska, and with the extreme wave-dominated environment, the unconsolidated sediment that was left on the shelf was effectively removed. Temperate carbonate sands make up the few sediment deposits presently found on the shelf. The Queen Charlotte fault, which lies just below the shelf break for most of its length, was extensively gullied during this short period of significant sed­iment discharge, when sediment was transported though the glacial valleys and across the narrow shelf through fluvial and submarine channels and was deposited offshore as sea level dropped. The Queen Charlotte fault became the western terminus of the glacio-isostatic forebulge, with the fault acting as a hinged flap taking up the uplift and collapse along the fault of 70+ m. This may have resulted in the development of the distinctive fault valley that presently acts as a very linear channel pathway for sediment throughout the fault system.

scholarly journals Sea level controls on buried geomorphology within the Swan River estuary during the Late Quaternary

2019 ◽  
Vol 2019 (1) ◽  
pp. 1-3 ◽  
Author(s):  
Giada Bufarale ◽  
Mick O’Leary ◽  
Alexandra Stevens
Keyword(s):  
Sea Level ◽  
Late Quaternary ◽  
River Estuary ◽  
Swan River
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