Foraminifera indicate Neogene evolution of Yongle Atoll from Xisha Islands in the South China Sea

Miocene Climatic Oscillation Recorded in the Lakes Entrance Oil Shaft, Southern Australia: Benthic Foraminiferal Response on a Mid-Latitude Margin

Coralline algal assemblages record Miocene sea-level changes in the South China Sea

Sea-level changes and carbonate platform evolution of the Xisha Islands (South China Sea) since the Early Miocene

87Sr/86Sr of coral reef carbonate strata as an indicator of global sea level fall: Evidence from a 928.75-m-long core in the South China Sea

Sea-level rise during Termination II inferred from large benthic foraminifers: IODP Expedition 310, Tahiti Sea Level

The sea level of the Black Sea coastal area is subject to non-periodic wind-induced fluctuations. Such fluctuations affect economic activity of the sea ports, enterprises and businesses located within the coastal area while those may be flooded when the sea level rises and, on the contrary, there is a threat of vessels grounding in case of sea level fall. There are several big sea ports which are located at the north-western part of the Black Sea and affected by wind-induced fluctuations. Therefore, the study of these processes and development of methods allowing their forecast are of great practical interest and this fact proves the topicality of the conducted research.
 The article's aim is to analyse wind-induced fluctuations within the water area of Yuzhnyi and Chornomorsk sea ports, identify statistical links between such fluctuations and wind characteristics / equations used for calculation of their values. The observations at Chornomorsk (2006-2013) and Yuzhnyi (2000-2011) stations show that within a year there are 1-2 upsurge-downsurge occurrences during an average month, however, the number of those increases up to 3-4 over the autumn-winter period. The average sea level rise at Chornomorsk station is equal to 34 cm, the average sea level fall – 38 cm, maximum values amount to 97 cm and 191 cm, respectively. The average sea level rise at Yuzhnyi station is equal to 30 cm, the average sea level fall – 34 cm, maximum values amount to 91 and 98 cm, respectively. The average duration of wind-induced fluctuations at both stations amount to 34-38 hours. In most cases the sea level rise is observed at Chornomosk station when winds blow from the South and the South-East, at Yuzhnyi station – when those blow from the South, the South-East and the South-West. The sea level fall is observed at Chornomosk station when winds blow from the North-West and the West, at Yuzhnyi station – when those blow from the North, the North-West and the North-East. Both stations are characterized with effective directions of wind causing occurrence of upsurge-downsurges. Based on the regression analysis equations for calculation of the sea level rise and fall values associated with wind characteristics were defined. The initial value of the sea level and the sum of the wind projections on effective directions for previous 30 hours are used as arguments in the equations. The accuracy of equation-based calculation constitutes 60-90%. The article offers recommendations on the use of equations when forecasting wind-induced fluctuations.

The apparent tectonic stability of the northern Puerto Rico platform during the late Oligocene and early Miocene allows for the depositional history of subsurface carbonate rocks of northeastern Puerto Rico to be related to major changes in eustatic sea level. During a late Oligocene north to south transgression of sea level, fluvial/deltaic to shallow marine terrigenous sediments (San Sebastian Formation) and, subsequently, open-ramp carbonates (Lares Limestone) accumulated in the central basin. Following a minor regression (third-order cycle ), a more extensive early Miocene( ) transgression resulted in deposition of deeper ramp carbonate mudstone and marl (Mudstone unit) in an apparent trough in the central basin, and open-ramp reefal carbonate (upper Lares) was deposited over a wider area of the basin. The San Sebastian Formation/Lares Limestone/Mudstone Unit sequence was most likely deposited during the second-order supercycle, TB{sub 1}. An early Miocene relative fall in sea level resulted in deposition of interfingering inner-ramp limestone and terrigenous sediments (Cibao Formation) and the development of subaerial costs, especially in the upper part of the unit. During a sea level rise, terrigenous deposition decreased and gave way to inner- and middle-ramp carbonate sediments (Los Puertos Limestone). A middle Miocene highstand in sea level brought basin-widemore » deposition of open-ramp carbonate sediments (Aymamon Ls). The Cibao Formation/Los Puertos Limestone/Aymamon. Limestone sequence may correspond to the second-order supercycle, TB{sub 2}. During the late middle Miocene( ), the carbonate platform was exposed and extensively karsted, possibly in an event related to the sea level drop at the end of TB{sub 2}.« less

The application of satellite altimetry allows us to acquire global sea level height data with higher spatial and temporal resolution, enabling a systematic understanding of spatial differences in sea level rise. In our study, we reconstructed the barystatic sea level and steric sea level change during the altimetry era (1993-2022). This involved utilizing mass change data and ocean heat content data from various sources. Notably, we incorporated the latest observation and model-simulation data, ensuring coverage of the entire altimetry era compared with previous reconstructions. Based on altimetry-observed relative sea level change, the global sea level rise rate is 3.38 [3.09 3.68] mm/yr, the global barystatic and steric sea level change is 1.80 [1.45 2.15] mm/my, and 1.02 [0.67 1.37] mm/yr, respectively. Subsequently, we further analyzed the regional characteristics of these sea level rises. Over the past three decades, sea levels have exhibited a faster rate of increase in the western basins, as well as in the equatorial and mid-latitude region, surpassing the global average. Conversely, sea level rise at higher latitudes has been relatively slower than the global average. In the mid-low latitude regions, the higher rate of sea level rise is primarily dominated by the expansion of ocean water due to its heating. In high-latitude regions, the lower sea level rise rate is primarily attributed to the far-field effects of the melting of land ice. The distribution of halosteric sea level changes is nearly uniform across latitudes. However, in the western Atlantic, a significant counteracting effect against the rise in thermosteric sea level is observed. This is linked to the weakening Atlantic Meridional Overturning Circulation (AMOC). Furthermore, we selected 8 regions, North Pacific (NP), South China Sea (SCS), Western Tropical Pacific (WTP), Bay of Bengal (BOB), Tropical Indian Ocean (TIO), Southwest Pacific (SWP), Gulf of Mexico (GOM), and North Atlantic (NA), with sea level rise rates faster than the global average. We analyzed the contributions of different components to the sea level rise in these areas. These regions are all adjacent to land or have a significant number of islands, the faster sea level rise poses a greater threat to the corresponding coastal areas. The contributions of barystatic and steric sea level components are approximately equal in most of these regions. However, in SCS and GOM, the contributions of the barystatic component exceed 60%. The halosteric sea level has a significant negative contribution to the sea level rise in the GOM and NA. The Antarctic Ice Sheet and Greenland Ice Sheet melting contribute to sea level rise in these regions by less than 15%, and more than 15%, respectively. The highest contribution of glacier melting is in the SCS, approximately 23%. Compared to the melting of land ice, changes in land water contribute limitedly to sea level rise in these regions. The contribution is less than 10%, except for in NA.

We examined uppermost Oligocene to lowermost Pliocene sections from four northeastern Gulf of Mexico boreholes for quantitative benthic foraminiferal faunal changes, stratigraphic ranges, paleobathymetry, organic carbon content, and planktonic foraminiferal relative abundances. The Eureka boreholes provide a depth transect in the De Soto Canyon area from the upper to lower bathyal zone: E68-136 (557m present depth, -600m paleodepth), E66-73 (857m present depth, 860-lOOOm paleodepth), E68-151A (1326m present depth, -1300m paleodepth), and E68-14 1A (1599m present depth, -1600m paleodepth). A number of taxa last appeared in the late Oligocene to early Miocene (Biochrons P22-N5) at E68-136; several of these disappearances constitute global last occurrences. A global benthic foraminiferal taxonomic turnover that began in the latest early Miocene in other parts of the ocean was restricted to the middle Miocene at E68-136 (Biochrons N9-N12), although faunal abundance changes began in late early Miocene Biochron N8. At middle bathyal borehole E66-73, ten taxa last occurred in Biochrons N8-N10, which is consistent with the timing of the taxonomic turnover in the Pacific and Atlantic. Depth-related faunal trends are examined and compared with previously published distributional data, resulting in revised paleobathymetric ranges of 12 taxa. Detailed age-paleodepth reconstructions reveal several stratigraphically and bathymetrically significant predominance biofacies in the northeast Gulf of Mexico: 1) Uvigerina pigmea dominated the middle-upper bathyal late Neogene; 2) Lenticulina spp. dominated the late Oligocenemiddle Miocene bathyal zone; 3) Oridorsalis spp., Gyroidinoides spp., and Globocassidulina subglobosa dominated the late Neogene lower bathyal zone; and 4) Uvigerina proboscidea was important in the late Neogene in the middle to upper bathyal zones. Four distinct bathymetric migrations are mapped, and 34 additional taxa are shown to have distinct paleobathymetric distributions. Planktonic foraminiferal biostratigraphic control allows us to evaluate the stratigraphic usefulness of benthic foraminiferal ranges. We revise the stratigraphic ranges of 12 bathyal benthic foraminiferal taxa, requiring re-correlation of the benthic foraminiferal zonal boundaries of Berggren and Miller (1989). INTRODUCTION Previous studies have shown that one of the largest benthic foraminiferal faunal changes of the Cenozoic occurred throughout the deep sea (>200m) in the late early to middle Miocene (Berggren 1972; Schnitker 1979, 1986; Woodruff and Douglas 1981; Boersma 1986; Thomas 1985, 1986a, 1886b, 1989, 1992; Woodruff 1985; Kurihara and Kennett 1986; Miller and Katz 1987; Thomas and Vincent 1987; Woodruff and Savin 1989; Miller et al. 1992; Thomas 1992; for an alternative view, see Boltovskoy and Boltovskoy 1988; Boltovskoy et al. 1992). These authors documented that major changes in taxonomic composition, percentages, and absolute abundances of benthic foraminifera began in the late early Miocene and culminated in the middle Miocene. Although this event has been well documented at open ocean locations, it remains poorly documented in marginal seas such as the Gulf of Mexico. The Eureka boreholes examined in this study (northeast Gulf of Mexico) yield faunal abundance changes and stratigraphic ranges that reflect this global middle Miocene benthic foraminiferal event. Benthic foraminiferal faunas have been recognized for their potential to assess paleobathymetry (e.g. Natland 1933; Bandy 1960). While Bandy (1960) promoted the concept that benthic foraminifera have distinct upper and lower depth limits, Streeter (1973) and Schnitker (1974) established that deep-water (>200m; bathyal-abyssal) benthic foraminifera are correlated to water mass properties that may vary independently of depth. Numerous subsequent studies have documented that deep-water benthic foraminiferal distributions are associated with physiochemical properties other than depth, and that depth alone does not control the vertical distribution of benthic foraminifera. For example, vertical distributions are correlated with water masses (e.g. Lohmann 1978; Corliss 1979; Schnitker 1979; Murray 1984; for Gulf of Mexico examples, see Pflum and 88? 86? 84? TEXT-FIGURE 1 Eureka bo ehole location map in the Gulf of Mexico. Contours are in meters. micropaleontology, vol. 39, no. 4, pp.367-403, plates 1-6, text-figures 1-32, tables 1-5, 1993 367 This content downloaded from 157.55.39.152 on Sat, 26 Nov 2016 04:11:28 UTC All use subject to http://about.jstor.org/terms M. E. Katz and K. G. Miller: Latest Oligocene to Earliest Pliocene benthicforaminiferal biofacies of the northeastern Gulf of Mexico TABLE 1 Age model parameters Datum Age (Ma) Depth (feet below sea level) E68-136 E66-73 E68-151 FO C. acutus & 5.

Evidence of mangrove habitat dynamics in relation to the Holocene sea-level changes offer significant bases for predicting the influence of an anticipated sea-level rise. We clarified the mangrove habitat dynamics during the mid to late Holocene in the southwestern coast of Thailand based on the relationships between ground level, sediments and present vegetation, spatial distribution of mangrove forest-floor deposits and their formative periods, The mangrove forest-floor deposits wereidentified by detailed observation of the sedimentary facies and vertical distribution of root density using non-disturbed core samples. Three cycles of sea-level fluctuations were found during the last 8000 years. The first sea-level fall occurred just before 7200 yr BP and mangrove forest moved seaward. The sea level fell up to about 3 m below present mean sea level. The rate of the subsequent sea-level rise, which was estimated at 4.7 mm/yr, exceeded the maximum rate of mangrove peat accumulation because the mangrove forests retreated landward. The maximum sea level was estimated to have reached more than 1 m above present mean sea level around 6150 yr BP. The sea-level fell slightly again before 4000 yr BP, after that it rose gradually up to about 1 m above present mean sea level around 3500 yr BP with the mangrove peat accumulation in Rhizophora apiculata forest, The sea-level fell again up to about 1 m below present mean sea level around 2200 yr BP and the mangrove habitat expanded seawaward. The R, apiculata habitat consisting of mangrove peat formed during the former high stand of sea level changed to the Lumnitzera littorea habitat with the sea-level fall. During the last 2000 years, the sea level rose gradually again at about O.6 mm/yr and the Rhizophora apiculata forests maintained their habitats by accumulating mangrove peat with the sea-level rise. In the depositional areas of inorganic sediments, whose sedimentation Tate was calculated at about 2 mm/yr, dominant species changed from R. apicutata to Bruguiera, Ceriops or Xylocarpus spp. with the increment of the ground level and the habitats have expanded laterally during the last several hundred years.

Xisha Area is located in the northern part of the South China Sea. The water depth is about 1000m to 3000m. Since Cenozoic , the Xisha area has experienced dual effects of extension and strike slip on the western margin, forming a special tectonic background of continental slope uplift. Overall, the Xisha area belongs to the continental slope system of the northern South China Sea. It is separated by the Qiongdongnan Basin to the north, on the west connected to the Yuedong Shelf , and  on the south and east ,adjacent to the deep-sea basin. It has developed three stages of sedimentation: fault depression, fault depression transformation, and depression. During the transition and depression periods, carbonate platform sediments developed due to rising sea levels and lacking of injection of terrestrial debris. After the Middle Miocene, the Xisha area was deep-water sedimentary environment on the continental slope, dominated by deep-sea to semi deep-sea sediments, with carbonate platform sediments developed on local uplifts. Under the special tectonic background, two types of deep-water sedimentary systems developed in the Xisha Sea during the Miocene period.During Miocene ,the Xisha Sea area was marine sedimentary environment, with developping two different types of deep-water sedimentary bodies. One type is a deep-water channel supplied by terrestrial debris from the Yuedong River system, and the other is a deep-water channel supplied by carbonate debris from the Xisha Platform. Deep water channels supplied by terrestrial debris are mainly influenced by ancient topography and sea level rise and fall, with strong mobility and mutual cutting characteristics between channels; Deep water channels supplied by carbonate rock debris are mainly influenced by ancient topography, with vertical accretion as the main source and weak mobility of the channels.The deep water channels filled with terrestrial debris developed in the research area are a process of low sea level and early marine invasion from the early to late stages of channel development. From the early stage to the late stage ,the limitation of deep water channels gradually becoming weaker, and the channels developping from a single channel with strong restriction in the early stage to a composite channel with multiple single channels cutting and overlapping each other in the middle stage, and then to late stage channel complexes and channelized lobes.In the Late Miocene, deep-water channels filled with carbonate rock debris developed in the Xisha Sea area, mainly in the depressions between the Guangle Platform and the Xisha Platform  and on the east side of the Huaguang sag. This type of deep-water channel developed in the early Late Miocene, and on seismic profiles, the reflection characteristics in the upstream and downstream are relatively similar, mainly consisting of a single channel vertically stacked. However, the location of the channel is different, and the characteristics of the channel also changed. The filling material of this type of channel is carbonate rock debris from the Xisha Platform, which has strong paleotopographic limitations and is mainly vertically accreted. 

Sequence stratigraphic analysis subdivides stratal packages into chronostratigraphic units composed of genetically related facies. Sequences are composed of stratal units that develop in response to changes in shelfal accommodation. Carbonate platform successions develop a hierarchy of sequences and cycles ranging from high (10,000 yrs.) to low (10-20 My supersequences) frequency. This stratigraphic hierarchy controls the facies distribution during long-term platform development. Due to the dominant organic origin of sediments, important differences exist between carbonates and siliciclastics that must be taken into account in a sequence analysis. Eustasy and tectonic subsidence control accommodation, and the health of the carbonate controls sediment supply. Generally, the bulk of deposition occurs during sea level highstands. Early marine cementation is not equal for all platforms. Platforms with steep foreslopes or platforms facing restricted basins will have long residence time in an active cementation environment, and are cement-rich. Highly productive platforms facing shallow basins will fill accommodation space rapidly, have a short residence time, and will be cement-poor. In general, sequence boundaries are regional onlap surfaces. Submarine erosional truncation commonly occurs at platform margins and on the slope. Abrupt facies truncation or dislocation is commonly present at sequence boundaries. The degree of subaerial alteration during sequence boundary formation will vary depending on the climate, the original mineralogy of the underlying highstand platform, and time. If the original mineralogy of a platform is dominantly aragonite and hi-Mg calcite the degree of alteration can be extensive. If the lowstand climate is relatively humid, platform-wide solution occurs that may extend deep into the highstand depending on the magnitude and duration of the sea level fall. If the climate is arid to semi-arid, only relatively minor karstification is predicted to occur. Low-Mg calcite-dominated systems show extensive karstification only during major multi-million year periods of subaerial exposure (i.e., 2nd-order sea level falls). Depositional slope angle and the degree of early cementation play a critical role in the development of lowstand systems tracts. In-situ, lowstand platforms and banks can develop in Type-1 sequences (1) in down ramp positions, and (2) on the slope and toe-of-slope of low-angle platforms. Where platform margins are steeper and well-cemented, lowstand deposition is characterized by abundant coarse debris eroded from the platform margin and slope areas. Steep, by-pass margins present a special case, as both transgressive and lowstand sedimentation may develop toe-of-slope onlap geometries. Significant transgressive carbonates will develop where paleoceanographic conditions permit the factory to keep-up with sea level rise. Well-circulated, shallow water conditions over a wide area (i.e., low slope or broad shelf) will allow a significant transgressive systems tract to develop. Integration of seismic, well log, and core data, paleontology, strontium age dating, and velocity analysis enabled construction of a sequence stratigraphic framework for the Gulf of Papua case study area. Rapid subsidence during early foreland development in the Gulf allowed development of thick Miocene platforms on isolated paleo-highs and hinged to the basin margin. Onlap above and erosional truncation below define sequence boundaries. Pervasive dolomitization and subaerial vuggy to cavernous porosity, extends below sequence boundaries for tens to hundreds of meters. Highstand systems tracts are characterized by mounded to chaotic seismic facies at platform margins. Platform interior seismic facies vary between parallel, concordant and mounded facies. Mounded facies are interpreted to be reefal buildups and parallel facies are interpreted to be flat lying lagoonal sediments. Platform foreslopes have gentle to steep dips depending on platform margin relief at basin margin positions. Lowstand systems tracts are observed at platform margins and comprise in-situ shallow water platform facies, and allochthonous debris. The Neogene comprises three 2nd-order supersequences, Lower Miocene, upper Lower to Middle Miocene, and Upper Miocene-Recent. These supersequences are divided into six Miocene and two Pliocene 3rd-order sequences. The Lower Miocene 2nd-order sea-level rise, combined with rapid subsidence, initiated platform growth. Reefal platforms kept pace with sea level rise and comprise the bulk of growth over isolated paleohighs. Although the western basin margin, Borabi platform trend kept pace with subsequent relative rises in sea level, rapid subsidence due to initial thrust sheet loading combined with an early Middle Miocene 2nd-order sea level rise drowned isolated platform growth centers in the Gulf basin area. Later forebulge development in the Middle-Late Miocene resulted in prolonged subaerial exposure of these drowned platforms. Renewed thrust sheet emplacement combined with the 2nd-order eustatic sea level rise during the latest Miocene and early Pliocene, drowned platforms throughout the Gulf and caused a major backstepping of the Borabi trend platforms. During the Pliocene to Recent, rapid influx of siliciclastics from the north and west onlapped and covered most reef platforms and deposition became restricted to the southern portion of the Borabi trend.

Palaeoenvironmental significance of Miocene larger benthic foraminifera from the Xisha Islands, South China Sea

On the basis of the satellite maps of sea level anomaly (MSLA) data and in situ tidal gauge sea level data, correlation analysis and empirical mode decomposition (EMD) are employed to investigate the applicability of MSLA data, sea level correlation, long-term sea level variability (SLV) trend, sea level rise (SLR) rate and its geographic distribution in the South China Sea (SCS). The findings show that for Dongfang Station, Haikou Station, Shanwei Station and Zhapo Station, the minimum correlation coefficient between the closest MSLA grid point and tidal station is 0.61. This suggests that the satellite altimeter MSLA data are effective to observe the coastal SLV in the SCS. On the monthly scale, coastal SLV in the western and northern part of SCS are highly associated with coastal currents. On the seasonal scale, SLV of the coastal area in the western part of the SCS is still strongly influenced by the coastal current system in summer and winter. The Pacific change can affect the SCS mainly in winter rather than summer and the affected area mostly concentrated in the northeastern and eastern parts of the SCS. Overall, the average SLR in the SCS is 90.8 mm with a rising rate of (5.0±0.4) mm/a during 1993–2010. The SLR rate from the southern Luzon Strait through the Huangyan Seamount area to the Xisha Islands area is higher than that of other areas of the SCS.

New evidence for episodic post-glacial sea-level rise, central Great Barrier Reef, Australia