Mid–Late Holocene coastal environmental changes in southeastern Sri Lanka: New evidence for sea level variations in southern Bay of Bengal

<p>Remote wind forcing plays a strong role in the Northern Indian Ocean, where oceanic anomalies can travel long distances within the coastal waveguide. Previous studies for instance emphasized that remote equatorial forcing is the main driver of the sea level and currents intraseasonal variability along the west coast of India (WCI). Until now, the main pathway for this connection between the equatorial and coastal waveguides was thought to occur in the eastern equatorial Indian Ocean, through coastal Kelvin waves that propagate around the Bay of Bengal rim and then around Sri Lanka to the WCI. Using a linear, continuously stratified ocean model, the present study demonstrates that two other mechanisms in fact dominate. First, the equatorial waveguide also intersects the coastal waveguide at the southern tip of India and Sri Lanka, creating a direct connection between the equator and WCI. Rossby waves reflected from the eastern equatorial Indian Ocean boundary indeed have a sufficiently wide meridional scale to induce a pressure signal at the Sri Lankan coast, which eventually propagates to the WCI as a coastal Kelvin wave. Second, local wind variations in the vicinity of Sri Lanka generate strong intraseasonal signals, which also propagate to the WCI along the same path. Sensitivity experiments indicate that these two new mechanisms (direct equatorial connection and local wind variations near Sri Lanka) dominate the WCI intraseasonal sea level variability, with the &#8220;classical&#8221; pathway around the Bay of Bengal only coming next. Other contributions (Bay of Bengal forcing, local WCI forcing) are much weaker.</p><p>We further show that the direct connection between the equatorial waveguide and WCI is negligible at seasonal timescale, but not at interannual timescales where it contributes to the occurrence of anoxic events. By providing an improved understanding of the mechanisms that control the WCI thermocline and oxycline variability, our results could have socio-economic implications for regional fisheries and ecosystems.</p>

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Catastrophic tidal expansion in the Bay of Fundy, CanadaEarth Sciences Sector (ESS) Contribution 20090423.

Canadian Journal of Earth Sciences ◽

10.1139/e10-046 ◽

2010 ◽

Vol 47 (8) ◽

pp. 1079-1091 ◽

Cited By ~ 31

Author(s):

John Shaw ◽

Carl L. Amos ◽

David A. Greenberg ◽

Charles T. O’Reilly ◽

D. Russell Parrott ◽

...

Keyword(s):

Water Temperature ◽

Sea Level ◽

Empirical Data ◽

Late Holocene ◽

Environmental Changes ◽

Aboriginal Peoples ◽

Bay Of Fundy ◽

Data Sets ◽

Level Data ◽

Tidal Amplification

Tidal models for the Bay of Fundy, Canada — site of the highest recorded modern tide — show that tidal amplification began in the early Holocene and by ca. 5000 BP the range was almost 80% of the present range. Empirical data consisting of 146 sea-level index points and other observations appear to contradict model results. Aggregated relative sea-level data for Chignecto Bay and Minas Basin show that rapid tidal expansion began ca. 3400 BP. However, if we separate these two geographically separate data sets, evidence for this rapid late-Holocene tidal expansion is confined to Minas Basin. We explain this singularity by positing a barrier at the mouth of Minas Basin, at the Minas Passage, that delayed tidal expansion. With the rapid breakdown of this barrier and near-instantaneous tidal expansion, water temperature dropped, tidal currents and turbidity increased, and the form of the inner estuary was changed from lagoonal–mesotidal to macrotidal. We argue that the catastrophic breakdown of the barrier is related in the aboriginal legend of Glooscap, showing that aboriginal peoples observed the rapid environmental changes and preserved an oral record for 3400 years.

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Mid- to late Holocene environmental and climatic changes in New Caledonia, southwest tropical Pacific, inferred from the littoral plain Gouaro-Déva

Quaternary Research ◽

10.1016/j.yqres.2011.04.007 ◽

2011 ◽

Vol 76 (2) ◽

pp. 229-242 ◽

Cited By ~ 10

Author(s):

Denis Wirrmann ◽

Anne-Marie Sémah ◽

Jean-Pierre Debenay ◽

Magali Chacornac-Rault

Keyword(s):

Sea Level ◽

Late Holocene ◽

Environmental Changes ◽

New Caledonia ◽

High Energy ◽

Climatic Changes ◽

Tropical Pacific ◽

Energy Conditions ◽

Enso Variability ◽

Freshwater Swamp

AbstractMultiproxy analysis of three littoral cores from western New Caledonia supports the hypothesis that the main controlling factors of environmental changes are sea-level change, ENSO variability and extra-tropical phenomena, such as the Medieval Warm Period (MWP) marked by a tendency for La Niña-like conditions in the tropical Pacific. The record starts during the late Holocene sea-level rise when the terrestrial vegetation indicated wet and cool conditions. The site was a coastal bay definitely transformed into a freshwater swamp at around 3400 cal yr BP, after the rapid drawdown of sea level to its current level. Sediments and foraminiferal assemblages indicated subsequent episodes of freshwater infillings, emersion or very high-energy conditions, likely related to climatic changes and mostly controlled by ENSO variability. Between 2750 and 2000 cal yr BP, relatively dry and cool climate prevailed, while wetter conditions predominated between ca. 1800 and 900 cal yr BP. The Rhizophoraceae peak between ca. 1080 and 750 cal yr BP, coeval with the MWP, may indicate a global phenomenon. Microcharcoal particles present throughout the record increased after 1500 cal yr BP, suggesting an anthropogenic source. From ca. 750 cal yr BP the appearance of current type of vegetation marks the human impact.

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Mid and late Holocene multiproxy analysis of environmental changes linked to sea-level fluctuation and climate variability of the Río de la Plata estuary

Palaeogeography Palaeoclimatology Palaeoecology ◽

10.1016/j.palaeo.2015.01.006 ◽

2015 ◽

Vol 421 ◽

pp. 75-88 ◽

Cited By ~ 18

Author(s):

Dominique Mourelle ◽

Aldo R. Prieto ◽

Laura Pérez ◽

Felipe García-Rodríguez ◽

C. Marcela Borel

Keyword(s):

Climate Variability ◽

Sea Level ◽

Late Holocene ◽

Environmental Changes ◽

Rio De La Plata ◽

Level Fluctuation ◽

Río De La Plata ◽

La Plata ◽

Sea Level Fluctuation

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Late Holocene Sea-Level Change on Rota and Guam, Mariana Islands, and Its Constraint on Geophysical Predictions

Quaternary Research ◽

10.1006/qres.1993.1071 ◽

1993 ◽

Vol 40 (2) ◽

pp. 189-200 ◽

Cited By ~ 20

Author(s):

Hajime Kayanne ◽

Teruaki Ishii ◽

Eiji Matsumoto ◽

Nobuyuki Yonekura

Keyword(s):

Sea Level ◽

Late Holocene ◽

Sea Level Change ◽

Mariana Islands ◽

Present Level ◽

Sea Level Changes ◽

Radiocarbon Dates ◽

Level Change ◽

Sea Level Variations ◽

Holocene Sea Level

AbstractHolocene emergent reefs and notches are well distributed on Rota and Guam. Relative sea-level changes at these islands are reconstructed based on geomorphological observations and borings on present and emergent reefs, together with 54 radiocarbon dates. Sea level rose gradually to a maximum of 1.8 m between 6000 and 4200 yr B.P. and reached its highest level by 4200 yr B.P. on both islands. After 3200 yr B.P. abrupt uplift caused emergence of the reef. By subtracting the tectonic effect, we obtained the sea-level change in the Marianas: sea level reached its present level by 4200 yr B.P. and has remained almost stable since then. Reconstructed late Holocene sea-level change in the Mariana Islands provides constraints on geophysical models of sea-level variations.

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Crustal subsidence inferred from reconstruction of the Pleistocene–Holocene palaeogeography in the northern Lake Inba area, central Japan

Quaternary Research ◽

10.1017/qua.2019.69 ◽

2019 ◽

Vol 94 ◽

pp. 61-79

Author(s):

Takashi Chiba ◽

Shigeo Sugihara ◽

Yoshiaki Matsushima ◽

Yusuke Arai ◽

Kunihiko Endo

Keyword(s):

Sea Level ◽

Late Holocene ◽

Environmental Changes ◽

Sea Level Changes ◽

Diatom Assemblages ◽

Central Japan ◽

Lower Salinity ◽

The Holocene ◽

Holocene Transgression

ABSTRACTTo help characterise the palaeogeographic and lacustrine environmental changes that resulted from the Holocene transgression and residual subsidence in the eastern Kanto Plain of central Japan, we analysed four drill cores and reviewed other core data from the southern part of the Lake Inba area. Fossil diatom assemblages yielded evidence of centennial-scale palaeogeographic and salinity responses to sea-level changes since the late Pleistocene. We determined that the seawater incursion into the Lake Inba area during the Holocene transgression occurred at approximately 9000 yr. We also recognised a late Holocene regression event corresponding to the Yayoi regression, considered to have occurred from ca. 3000 to ca. 2000 yr, and a subsequent transgression. Our data clarify some of the palaeogeographic changes that occurred in the Lake Inba area and document an overall trend toward lower salinity in the lake during the regression. In particular, the environment in Lake Inba changed from brackish to freshwater no later than 1000 yr. From the detailed palaeogeographic and palaeo-sea-level reconstruction, we recognised that residual subsidence occurred during the Holocene in this area. Thus, comparison of sea-level reconstructions based on modelling and fossil diatom assemblages is effective in interpreting Holocene long-term subsidence.

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Foraminiferal Evidence of Late Holocene Sea-Level Change and Amerindian Site Distribution at Montague Harbour, British Columbia

Géographie physique et Quaternaire ◽

10.7202/033073ar ◽

2007 ◽

Vol 50 (1) ◽

pp. 35-46 ◽

Cited By ~ 7

Author(s):

Eduard G. Reinhardt ◽

Norman A. Easton ◽

R. Timothy Patterson

Keyword(s):

British Columbia ◽

Sea Level ◽

Late Holocene ◽

Environmental Changes ◽

Tectonic Subsidence ◽

Archaeological Remains ◽

Sea Level Changes ◽

Site Distribution ◽

Low Salinity ◽

Holocene Sea Level

ABSTRACT Foraminiferal and sedimentological analysis of an underwater stratigraphie section from an Amerindian habitation site at Montague Harbour, British Columbia has further documented late Holocene sea level changes. It appears that part of the documented transgression was caused by tectonic subsidence of the area (Event 1 at approx. 3500 calendar years BP and Event 2 sometime before 1100 calendar years BP) and was recognized in the stratigraphie record by rapid environmental changes. The environmental changes caused by rapid shifts in water depth were recognized through sedimentological and foraminiferal evidence. The tectonic subsidence events, coupled with gentle late Holocene transgression, caused the breaching of Montague Harbour's northwestern channel. The breaching of the channel improved water circulation and increased salinity within the harbour. The salinity changes are reflected in the shift from a low salinity Cribroelphidium excavatum (Terquem, 1876) phenotype "clavata" dominated biofacies (1) at the base of the section to a higher salinity Buccella tenerrima (Bandy, 1950) and Elphidiella hannai (Cushman and Grant, 1927) dominated biofacies (2) at the top. These sea-level changes would have eventually forced local Amerindian settlements inland. The 14C dating of wood and shell, indicates that the recovery of archaeological remains of the Charles culture (ca.6500-3200 years BP) requires investigation in deeper waters.

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PERUBAHAN LINGKUNGAN DAN EVOLUSI MANGROVE DI PULAU BELITUNG SELAMA HOLOSEN AKHIR BERDASARKAN REKAMAN POLEN

JURNAL GEOLOGI KELAUTAN ◽

10.32693/jgk.17.2.2019.578 ◽

2019 ◽

Vol 17 (2) ◽

Author(s):

Woro Sri Sukapti ◽

Eko Yulianto ◽

Praptisih Praptisih

Keyword(s):

Environmental Change ◽

Sea Level ◽

Late Holocene ◽

Environmental Changes ◽

Onset Time ◽

Pollen Record ◽

Shelf Area ◽

Level Fluctuation ◽

Sunda Shelf ◽

Sea Level Fluctuation

Studi sejarah fluktuasi muka air laut dan perubahan lingkungan di Paparan Sunda masih sedikit dilakukan. Ada dua isu yang saling terkait yang menjadi permasalahan utama terkait dengan perubahan muka air laut di wilayah ini yaitu kurangnya rekaman data fluktuasi muka air laut dan perubahan lingkungan selama kurun waktu mid-late Holosen dengan kualitas yang bagus. Hal itu memiliki konsekwensi terhadap munculnya isu kedua yaitu tidak terdefinisikannya secara jelas dan tepat baik waktu maupun besaran posisi muka air laut pada saat mid-Holosen. Penelitian ini dilakukan untuk merekonstruksi perubahan lingkungan selama Holosen Akhir di wilayah Paparan Sunda menggunakan rekaman polen endapan mangrove. Pemboran tangan dilakukan guna pengamatan stratigrafi dan pengambilan sampel untuk analisis-analisis sedimentologi dan mikropaleontologi di laboratorium. Hasil studi ini menunjukkan bahwa perubahan lingkungan terjadi di Pulau Belitung selama setidaknya 1500 tahun terakhir sebagai akibat dari proses progradasi. Proses ini menyebabkan garis pantai terus maju hingga mencapai posisi saat ini. Endapan mangrove di lokasi penelitian juga merekam kejadian insidentil yang secara hipotetis diduga sebagai peristiwa tsunami akibat letusan Krakatau yang terjadi pada tahun 1883 AD dan sekitar 535-536 AD.Kata Kunci: Belitung, polen, mangrove, Mid-Holosen, Krakatau, muka laut, perubahan lingkungan.There is only minor study on sea-level fluctuation and environmental change in Sunda Shelf. The main isues in this area are lacking good quality of sea-level fluctuation and environmental change record during mid-late Holocene in which accordingly the onset time and sea-level height of the Mid-Holocene Maximum Transgression event have not been well defined. This study aims to reconstruct environmental changes during late Holocene in the Sunda Shelf area based on mangrove pollen record. Hand-auger was applied to make stratigraphic observation and sampling for sedimentological and micropaleontological analyses in the laboratory. Result of this study shows environmental changes occured within the last ca.1500 years due to coastal progradation in Belitung. This progradation shifted the coastal line seaward to attain the present position. The pollen record also reflects rapid and brief changes that may hypothetically be interpreted as the 535-536 AD and 1883 AD Krakatau tsunamis.Keywords: Belitung, pollen, mangroves, Mid-Holocene, Krakatau, sea level, environmental changes.

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INFLUENCIA DEL RÍO ATRATO EN EL GOLFO DE URABÁ DURANTE EL HOLOCENO TARDÍO, MAR CARIBE COLOMBIANO

Bulletin of Marine and Coastal Research ◽

10.25268/bimc.invemar.2016.45.1.631 ◽

2016 ◽

Vol 45 (1) ◽

Cited By ~ 1

Author(s):

Camilo Vélez Agudelo ◽

Néstor Aguirre Ramírez

Keyword(s):

Sea Level ◽

Late Holocene ◽

Environmental Changes ◽

Sediment Cores ◽

Anthropogenic Factors ◽

Northwestern Margin ◽

Hydrodynamic Processes ◽

Delta Progradation ◽

Del Rio ◽

Northern Branch

Sedimentary, geochemical (total organic carbon TOC, total nitrogen TN, total phosphorus TP, biogenic silica BSi and calcium carbonate (CaCO3) and diatoms data of two sediment cores were used to infer general environmental changes in the northern Gulf of Urabá during the late Holocene. The age models (AMS 14C ) suggested that core of the northeastern margin (SP 9) belong to ~960 years BP, while in the core of the northwestern margin (SP 41) the model was adjusted for the last ~2845 years BP. The results indicated that drilling sites are affected by different hydrodynamic processes that, in general, have been maintained during the late Holocene. While in the northwestern margin oceanic processes dominate and there is low input of fluvial sediments to this site, in the northeastern margin there are processes that favor the transport and accumulation of terrigenous sediments, which limit the growth of diatoms. Between 2845 and 2489 year BP, a higher sea level and wet conditions were recorded in the gulf. Since ~2445 years BP a gradual decrease in sea level allowed delta progradation towards the eastern side of the gulf. Apparently, this process would have intensified its presence in the last ~200 year BP, due to natural and anthropogenic factors. Even though the river discharges are channeled predominantly towards the east side of the Gulf, the trend of increasing TOC and diatoms data suggested fluvial input to the northwestern margin from ~800 years BP, which may be associated with a higher activity of Tarenas mouth, the northern branch of the Atrato River.

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