A standardized database of Last Interglacial sea-level indicators in southeast Asia: Records from coral reef terraces in a tectonically complex region

Author(s):  
Kathrine Maxwell ◽  
Hildegard Westphal ◽  
Alessio Rovere

<p>The Last Interglacial (LIG), as well as other warmer periods in the Earth’s geologic history, provides an analogue for predicted warming conditions in the near future. Analysis of sea-level indicators during this period is important in constraining regional drivers of relative sea-level change (RSL) and in modeling future trajectories of sea-level rise. In southeast Asia, several studies have been done to examine LIG sea-level indicators such as coral reef terraces and tidal notches. A synthesis of the state-of-the-art of the LIG RSL indicators in the region, meanwhile, has yet to be done. We reviewed over 50 published works on the LIG RSL indicators in southeast Asia and used the framework of the World Atlas of Last Interglacial Shorelines (WALIS) in building a standardized database of previously published LIG RSL indicators in the region. In total, we identified 38 unique RSL indicators and inserted almost 140 ages in the database. Available data from Indonesia, the Philippines, and East Timor points to variable elevation of sea-level indicators during the LIG highlighting the complex tectonic setting of this region. Variable uplift rates (from as low as 0.02 to as high as 1.1 m/ka) were reported in the study areas echoing various collision and subduction processes influencing these sites. Although several age constraints and elevation measurements have been provided by these studies, more data is still needed to shed more light on the RSL changes in the region. With this effort under the WALIS framework, we hope to identify gaps in the LIG RSL indicators literature in SE Asia and recognize potential areas that can be visited for future work. We also hope that this initiative will help us further understand the different drivers of past sea-level changes in SE Asia and will provide inputs for projections of sea-level change in the future.</p>

2021 ◽  
Vol 13 (9) ◽  
pp. 4313-4329
Author(s):  
Kathrine Maxwell ◽  
Hildegard Westphal ◽  
Alessio Rovere

Abstract. Marine Isotope Stage 5e (MIS 5e; the Last Interglacial, 125 ka) represents a process analog for a warmer world. Analysis of sea-level proxies formed in this period helps in constraining both regional and global drivers of sea-level change. In Southeast Asia, several studies have reported elevation and age information on MIS 5e sea-level proxies, such as fossil coral reef terraces or tidal notches, but a standardized database of such data was hitherto missing. In this paper, we produced such a sea-level database using the framework of the World Atlas of Last Interglacial Shorelines (WALIS; https://warmcoasts.eu/world-atlas.html). Overall, we screened and reviewed 14 studies on Last Interglacial sea-level indicators in Southeast Asia, from which we report 43 proxies (42 coral reef terraces and 1 tidal notch) that were correlated to 134 dated samples. Five data points date to MIS 5a (80 ka), six data points are MIS 5c (100 ka), and the rest are dated to MIS 5e. The database compiled in this study is available at https://doi.org/10.5281/zenodo.5040784 (Maxwell et al., 2021).


2021 ◽  
Author(s):  
Kathrine Maxwell ◽  
Hildegard Westphal ◽  
Alessio Rovere

Abstract. Marine Isotope Stage 5e (the Last Interglacial, LIG) represents a process analogue for a warmer world expected for the near future. Analysis of LIG relative sea level (RSL) proxies helps in constraining both regional and global drivers of sea-level change. In Southeast Asia, several studies have reported elevation and age information on LIG RSL proxies, such as fossil coral reef terraces or tidal notches, but a standardized database of such data was hitherto missing. In this paper, we produced such sea-level database using the framework of the World Atlas of Last Interglacial Shorelines (WALIS, https://warmcoasts.eu/world-atlas.html). Overall, we screened and reviewed 14 studies on LIG sea-level indicators in Southeast Asia, from which we report 43 unique RSL proxies (42 coral reef terraces and one tidal notch), that were correlated to 134 dated samples. The database compiled in this study (Maxwell et al., 2021) is available at https://doi.org/10.5281/zenodo.4681325.


2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Yusuke Yokoyama ◽  
Anthony Purcell

AbstractPast sea-level change represents the large-scale state of global climate, reflecting the waxing and waning of global ice sheets and the corresponding effect on ocean volume. Recent developments in sampling and analytical methods enable us to more precisely reconstruct past sea-level changes using geological indicators dated by radiometric methods. However, ice-volume changes alone cannot wholly account for these observations of local, relative sea-level change because of various geophysical factors including glacio-hydro-isostatic adjustments (GIA). The mechanisms behind GIA cannot be ignored when reconstructing global ice volume, yet they remain poorly understood within the general sea-level community. In this paper, various geophysical factors affecting sea-level observations are discussed and the details and impacts of these processes on estimates of past ice volumes are introduced.


2020 ◽  
Author(s):  
Martina Conti ◽  
Martin Bates ◽  
Natasha Barlow ◽  
Richard Preece ◽  
Kirsty Penkman ◽  
...  

<p>Targeted analysis of organic matter in soils and sediments is useful for evaluating past environmental conditions, as specific compounds may be directly linked to organisms and hence to the conditions in which they inhabited the environment.  Variations in molecular fossil distributions have become a powerful tool for understanding changes in palaeoclimate conditions.  This work uses molecular fossils to give an insight into the impact of transgressive events on primary producers inhabiting the studied basin, and hence a more detailed record of sea-level change.</p><p>The cores studied consisted of unconsolidated immature sediments from the mid-late Pleistocene (< 500,000 years) and the Holocene.  Molecular fossils, such as chlorophyll pigments and lipids, exhibit fluctuations as a response to changes in palaeoenvironmental conditions, providing a useful marker for sea-level changes.  Fluctuations in the pigment and <em>n</em>-alkane distribution reflect changes in primary producer activity, while the GDGT-based index of branched and isoprenoid tetraether lipids (BIT) differentiates between terrigenous and marine organic matter inputs.  Lipids were analysed by GC-FID and HPLC-MS while analysis of chlorophyll pigments was carried out using a new UHPLC-DAD method.</p><p>The results from biomarker analyses show excellent time-resolved agreement with previous lithological and ecological studies, but enabled a more sensitive response of different primary producers to changing conditions to be observed.  The molecular fossils were able to detect the onset and cessation of the studied transgressions earlier than it was possible with microfossil evidence.  Linking the pigment and lipid record with more secure dating will enable a more accurate record of Quaternary relative sea-level change.</p>


1999 ◽  
Vol 26 (3) ◽  
pp. 169-178 ◽  
Author(s):  
E.A. BALDINA ◽  
J. DE LEEUW ◽  
A.K. GORBUNOV ◽  
I.A. LABUTINA ◽  
A.F. ZHIVOGLIAD ◽  
...  

During the twentieth century the level of the Caspian Sea dropped from -26 m (1930) to -29 m (1977) below global sea level and subsequently rose again to -26.66 m in 1996. We aimed to describe responses of the vegetation in the lower Volga Delta to these substantial sea-level changes using an analysis of historic vegetation maps produced by aerial photography and satellite imagery.The sea level drop in the earlier part of the century was followed by rapid progression of the vegetation. The subsequent rapid sea-level rise in the 1980s did however not result in similarly rapid regression of the vegetation. This partial irreversibility of the vegetation response to sea-level change is explained by the wide flooding tolerance of the major emergent species, namely Phragmites australis. Floating vegetation increased in extent, most likely due to the increased availability of more favourable conditions, particularly for Nelumbo nucifera, a tropical plant reaching its northernmost distribution in the Volga Delta. This species increased in distribution from 3.5 ha in the 1930s throughout the entire Volga Delta to several thousands of hectares in the Astrakhanskiy Biosphere Reserve alone in the 1980s. The reported sea-level changes swept the ecosystems in the Astrakhanskiy Biosphere Reserve back and forth within the Reserve boundaries. At longer time scales, ten-fold greater sea-level change has been reported. The ecosystems for which the Reserve is renowned might be pushed completely out of the Reserve under these conditions. We therefore question whether the current Reserve will be sufficiently large to guarantee conservation of the biota in the lower Volga Delta at longer time scales.


2014 ◽  
Vol 11 (1) ◽  
pp. 123-169 ◽  
Author(s):  
T. Howard ◽  
J. Ridley ◽  
A. K. Pardaens ◽  
R. T. W. L. Hurkmans ◽  
A. J. Payne ◽  
...  

Abstract. Climate change has the potential to locally influence mean sea level through a number of processes including (but not limited to) thermal expansion of the oceans and enhanced land ice melt. These lead to departures from the global mean sea level change, due to spatial variations in the change of water density and transport, which are termed dynamic sea level changes. In this study we present regional patterns of sea-level change projected by a global coupled atmosphere–ocean climate model forced by projected ice-melt fluxes from three sources: the Antarctic ice sheet, the Greenland ice sheet and small glaciers and ice caps. The largest ice melt flux we consider is equivalent to almost 0.7 m of global sea level rise over the 21st century. Since the ice melt is not constant, the evolution of the dynamic sea level changes is analysed. We find that the dynamic sea level change associated with the ice melt is small, with the largest changes, occurring in the North Atlantic, contributing of order 3 cm above the global mean rise. Furthermore, the dynamic sea level change associated with the ice melt is similar regardless of whether the simulated ice fluxes are applied to a simulation with fixed or changing atmospheric CO2.


2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Tristan Salles ◽  
Claire Mallard ◽  
Laurent Husson ◽  
Sabin Zahirovic ◽  
Anta-Clarisse Sarr ◽  
...  

AbstractSundaland, the inundated shelf separating Java, Sumatra and Borneo from the Malay Peninsula, is of exceptional interest to biogeographers for its species richness and its position at the junction between the Australasian and Indomalay biogeographic provinces. Owing to its low elevation and relief, its physiography is contingent on relative sea-level change, which drove Quaternary species burst in response to flooding episodes. New findings show that the region was predominantly terrestrial during the Late Pleistocene requiring a reassessment of the drivers of its recent biodiversity history. Here we show that physiographic changes have modified the regional connectivity network and remodelled the pathways of species dispersal. From combined landscape evolution and connectivity models, we found four phases of drainage reorganisation and river captures. These changes have fragmented the environment into multiple habitats connected by migratory corridors that cover 8% of the exposed shelf and stretch across the biogeographic provinces. Our results support the theory that rapidly evolving physiography could foster Quaternary biodiversification across Southeast Asia.


2021 ◽  
Author(s):  
Omid Memarian Sorkhabi

Abstract Today, despite the satellite altimetry, it is possible to determine the average sea level and determine the sea level change with high accuracy. In this research, data from 1992-2017 TOPEX / Poseidon, Jason1, OSTM and Jason3 altimeter satellites in the Caspian Sea have been used. The results show that every year the average of 75 mm of the Caspian Sea water level decreases and the downward trend.


2021 ◽  
Author(s):  
Omid Memarian Sorkhabi

Abstract Today, despite the satellite altimetry, it is possible to determine the average sea level and determine the sea level change with high accuracy. In this research, data from 1992-2017 TOPEX / Poseidon, Jason1, OSTM and Jason3 altimeter satellites in the Caspian Sea have been used. The results show that every year the average of 75 mm of the Caspian Sea water level decreases and the downward trend.


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