Ice Induced Sea Level Change in the Late Neogene

<p>Two independent records of latest Neogene (2,0 - 6.0 Ma.) glacioeustasy are presented, one of Antarctic ice volume from East Antarctica and the other of eustatic sea level from the South Wanganui Basin, New Zealand. Glacial deposits in the Transantarctic Mountains (Sirius Group) and sediment at the Antarctic continental margin provide direct evidence of Antarctic ice sheet fluctuation. Evidence for deglaciation includes the occurrence of Pliocene marine diatoms in Sirius Group deposits, which are sourced from the East Antarctic interior. K/Ar and 39Ar/40Ar dating of a tuff in the CIROS-2 drill-core confirms their Pliocene age at high latitudes (78 [degrees] S) in Antarctica. Further evidence for Antarctic ice volume fluctuation is recorded by glaciomarine strata from the Ross Sea Sector cored by the CIROS-2 and DVDP-11 drill-holes. Magnetostratigraphy integrated with Beryllium-10, K/Ar and 39Ar/40Ar dating provides a high resolution ([plus or minus] 50 k.y.) chronology of events in these strata. In the Wanganui Basin, New Zealand, a 5 km thick succession of continental shelf sediments, now uplifted, records Late Neogene eustatic sea level fluctuation. In the Late Neogene, basin subsidence equalled sediment input allowing eustatic sea level fluctuation to produce a dynamic alternation of highstand, transgressive, and lowstand sediment wedges. This record of Late Neogene sea level variation is unequalled in its resolution and detail. Magnetostratigraphy provides a high resolution chronology for these sedimentary cycles as well as magnetic tie lines with the Antarctic margin record in McMurdo Sound. These two independent records of Late Neogene glacioeustasy are in good agreement and record the following history: The Late Miocene and Late Pliocene are times of low 'base level' glacioeustasy (here termed glacialism, rather than glacial), with growth of continental-scale ice sheets on the Antarctic continent causing a lowering of global sea level. The Early Pliocene was a time of high 'base level' glacioeustasy (here termed interglacialism, rather than interglacial), driven by collapsing of continental-scale ice sheets to local and subcontinental ice caps. The middle Pliocene is marked by a move into glacialism with an increasing 'base level' of glacioeustatic fluctuation. Higher-order glacial advances and associated eustatic sea-level lowering occurred at approximately 3.5 and 4.3 Ma., separating the Early Pliocene into 3 sea-level stages. Still higher-order glacioeustatic fluctuations are recognised in this study, with durations of 50 Ka. and 100 - 300 Ka.. The 100 - 300 Ka. duration cycles are prominent during interglacialisms, and the 50 Ka. duration cycles are prominent during glacialisms. These shorter duration fluctuations in glacioeustasy have already been recognised as glacial/deglacial cycles from detailed studies of the Quaternary. Four orders of sea-level fluctuation are recognised within the Late Neogene, these are of approximately 0.05 Ma., 0.1-0.3 Ma., 2 Ma., and 4 Ma. in duration. The 2 Ma. and 4 Ma. duration cycles are subdivisions of the third order cyclicity recognised by Vail et al. (1991) (referred to here as cyclicity orders 3a and 3b). The 0.1-0.3 Ma. duration cycles are a subset of the fourth order cyclicity recognised Vail et al. (1991), and the 0.05 Ma. Duration cycles are a subset of the 5 th order cyclicity recognised by Vail et al. (1991). 3a, 3b and 4 th order sea level fluctuations are driven by fluctuations in the volume of the Antarctic Ice Sheet. Fifth order sea level fluctuations are also suggested to be at least partially driven by fluctuations in the volume of the Antarctic Ice Sheet. Milankovitch cyclicities in glacioeustasy (<100 Ka., fifth order cyclicity) are prominent in the geologic record at times when there is large scale glaciation (glacialism) of the Antarctic Continent (e.g. for the Pleistocene). Conversely, at times when the Antarctic continent is in a deglaciated state (deglacialism) fourth order cyclicity is more prominent, with Milankovitch cyclicities present at a parasequence level.</p>

Ice Induced Sea Level Change in the Late Neogene

<p>Two independent records of latest Neogene (2,0 - 6.0 Ma.) glacioeustasy are presented, one of Antarctic ice volume from East Antarctica and the other of eustatic sea level from the South Wanganui Basin, New Zealand. Glacial deposits in the Transantarctic Mountains (Sirius Group) and sediment at the Antarctic continental margin provide direct evidence of Antarctic ice sheet fluctuation. Evidence for deglaciation includes the occurrence of Pliocene marine diatoms in Sirius Group deposits, which are sourced from the East Antarctic interior. K/Ar and 39Ar/40Ar dating of a tuff in the CIROS-2 drill-core confirms their Pliocene age at high latitudes (78 [degrees] S) in Antarctica. Further evidence for Antarctic ice volume fluctuation is recorded by glaciomarine strata from the Ross Sea Sector cored by the CIROS-2 and DVDP-11 drill-holes. Magnetostratigraphy integrated with Beryllium-10, K/Ar and 39Ar/40Ar dating provides a high resolution ([plus or minus] 50 k.y.) chronology of events in these strata. In the Wanganui Basin, New Zealand, a 5 km thick succession of continental shelf sediments, now uplifted, records Late Neogene eustatic sea level fluctuation. In the Late Neogene, basin subsidence equalled sediment input allowing eustatic sea level fluctuation to produce a dynamic alternation of highstand, transgressive, and lowstand sediment wedges. This record of Late Neogene sea level variation is unequalled in its resolution and detail. Magnetostratigraphy provides a high resolution chronology for these sedimentary cycles as well as magnetic tie lines with the Antarctic margin record in McMurdo Sound. These two independent records of Late Neogene glacioeustasy are in good agreement and record the following history: The Late Miocene and Late Pliocene are times of low 'base level' glacioeustasy (here termed glacialism, rather than glacial), with growth of continental-scale ice sheets on the Antarctic continent causing a lowering of global sea level. The Early Pliocene was a time of high 'base level' glacioeustasy (here termed interglacialism, rather than interglacial), driven by collapsing of continental-scale ice sheets to local and subcontinental ice caps. The middle Pliocene is marked by a move into glacialism with an increasing 'base level' of glacioeustatic fluctuation. Higher-order glacial advances and associated eustatic sea-level lowering occurred at approximately 3.5 and 4.3 Ma., separating the Early Pliocene into 3 sea-level stages. Still higher-order glacioeustatic fluctuations are recognised in this study, with durations of 50 Ka. and 100 - 300 Ka.. The 100 - 300 Ka. duration cycles are prominent during interglacialisms, and the 50 Ka. duration cycles are prominent during glacialisms. These shorter duration fluctuations in glacioeustasy have already been recognised as glacial/deglacial cycles from detailed studies of the Quaternary. Four orders of sea-level fluctuation are recognised within the Late Neogene, these are of approximately 0.05 Ma., 0.1-0.3 Ma., 2 Ma., and 4 Ma. in duration. The 2 Ma. and 4 Ma. duration cycles are subdivisions of the third order cyclicity recognised by Vail et al. (1991) (referred to here as cyclicity orders 3a and 3b). The 0.1-0.3 Ma. duration cycles are a subset of the fourth order cyclicity recognised Vail et al. (1991), and the 0.05 Ma. Duration cycles are a subset of the 5 th order cyclicity recognised by Vail et al. (1991). 3a, 3b and 4 th order sea level fluctuations are driven by fluctuations in the volume of the Antarctic Ice Sheet. Fifth order sea level fluctuations are also suggested to be at least partially driven by fluctuations in the volume of the Antarctic Ice Sheet. Milankovitch cyclicities in glacioeustasy (<100 Ka., fifth order cyclicity) are prominent in the geologic record at times when there is large scale glaciation (glacialism) of the Antarctic Continent (e.g. for the Pleistocene). Conversely, at times when the Antarctic continent is in a deglaciated state (deglacialism) fourth order cyclicity is more prominent, with Milankovitch cyclicities present at a parasequence level.</p>

New insight on tide-dominated estuary and delta in the Eocene-Miocene Mrayt Group, North-Western Rif, Morocco

The sedimentary deposits of Eocene-Miocene Mrayt Group, North-Western Rif, Morocco has been the subject of controversy by previous authors regarding their depositional environment. Detailed sedimentological study based on petrographic and sedimentary facies analysis, ichnofacies interpretation and paleocurrent measurements, leads to several results and new insights. Petrographic study provided the first evidence of mixed siliciclastic and carbonate sediments and their nomenclature: silty micrites, micritic siltstones, micritic sandstones, sandy micrite, and allochemic sandstones, as well as the nature of the sources and its geological context. Twenty two sedimentary facies that have never been described before are identified, and based on their succession and association a new interpretation of depositional processes and depositional systems are proposed. The paleoenvironments of the Mrayt Group are interpreted as littoral and shallow marine settings: tides- dominated estuary, tides-dominated delta systems and open coast tidal flat, under complex hydrodynamics strongly influenced by river discharge, tidal currents, waves and storms action.Sedimentation occurred in “the Maghrebian basin” under the interplay of: i) tectonics related to the Cenozoic collision of the African and Eurasian continental plates, ii) Cenozoic alternation of warm climate and cooling due to the increasing influence of Antarctica glaciation, iii) sediments supplies induced by rejuvenation of sedimentary sources and iv) sea level fluctuation related to the advance and retreat of ice-sheet on Antarctica.

Karakteristik Perubahan Lingkungan Akhir Plistosen - Holosen di Dataran Rendah Aluvial dan Pantai Wilayah Demak, Kudus, Jepara, Pati dan Sekitaranya

ABSTRAKWilayah dataran aluvial hingga pantai daerah Demak, Kudus, Jepara, Pati dan sekitarnya ditutupi endapan sedimen Holosen yang terdiri atas kerikil, pasir, lempung, lanau, dan bongkah batuan gunungapi. Penelitian dilakukan dengan analisis sedimentologi dan stratigrafi terhadap 37 pemboran berskala 1 : 100 dengan ketebalan sedimen antara 0,8 - 18 meter. Berdasarkan korelasi data hasil pemboran diketahui bahwa sedimen Holosen di wilayah ini dapat dibedakan dalam tiga interval proses pengendapan (IPP A- C). Perubahan sedimen secara vertikal dapat diwakili oleh setiap sub-IPP yang merupakan hasil dari proses eksternal sesuai perubahan iklim, fluktuasi muka laut, tektonik dan aktivitas gunungapi. Dari hasil analisis stratigrafi diketahui bahwa perubahan lingkungan pengendapan pada daerah penelitian berhubungan dengan aktivitas proses eksternal di cekungan ini. Peranan proses eksternal ini diharapkan menjadi variabel dalam perumusan kebijakan pengelolaan lingkungan di wilayah Demak, Kudus, Jepara, Pati, dan sekitarnya.Kata kunci: fluktuasi muka air laut, Holosen, lingkungan, tektonik, perubahan iklimABSTRACTThe alluvial plain to the coast of Demak, Kudus, Jepara, Pati, and its surroundings is covered with sedimentary Holocene deposits consisting of gravel, sand, clay, silt, and volcanic rock boulders. The study used sedimentology and stratigraphic analysis of 37 drilling points with sediment thicknesses between 0.8-18 meters. Based on the correlation of drilling results, the Holocene sediments in the area of research can be distinguished in three deposition process (IPP) intervals. Vertically, sediment changes can be represented by each sub-IPP which are the result of external processes according to climate change, sea-level fluctuations, tectonics, and volcanic activity. From the results of the stratigraphic analysis, the changes in the depositional environment in the study area are related to external process activities in the basin. The effects of this external process are expected to be a recommendation in the future environmental development in the Demak, Kudus, Jepara, Pati, and its surroundings.Keywords: sea-level fluctuation, Holocene, environment, tectonic, climate change

Quaternary evolution and paleoclimatology of the coastal cave of Selinitsa (SW Peloponnese, Greece) based on geomorphological and geochemical data

&lt;p&gt;The present study examines the Quaternary evolution of the Selinitsa coastal cave in SW Peloponnese, in an attempt to provide new insights on the paleogeographical and paleoclimatological conditions of the Eastern Mediterranean Sea. The entrance of Selinitsa Cave is located +18 m above present sea level (a.p.s.l.) on the eastern coast of Messiniakos Gulf (SW Peloponnese), an area of constant uplift since Middle Pleistocene. Considering the phreatic origin of Selinitsa and the presence of sea level indicators at its entrance (biological and geomorphological markers such as tidal notches and &lt;em&gt;Lithophaga&lt;/em&gt; borings), all together qualify the cave suitable for the study of former sea level changes and more particularly, those during the last interglacial period. The MIS 5e is considered the most suitable geological period for the estimation of future sea level rise due to the plethora of geological data at-or-near the coastal zone combined to sea-level fluctuation circles from Middle Pleistocene to-date. Previous results from Selinitsa Cave place the sea level of the latest phase of the last interglacial at +18 m a.p.s.l.&lt;/p&gt;&lt;p&gt;The Eastern Mediterranean is the least studied area relative to the Western Mediterranean, regarding sea level changes during Marine Isotope Stage 5e (MIS 5e). In order to reconstruct the paleogeography of the area and shed light on the climatic conditions of this period, our study involved geological mapping, field measurements and identification of geomorphological features (marine terraces, coastal caves and former sedimentary tidal environments). Additionally, 3D mapping of Selinitsa was conducted in order to precisely define its relative location in respect to the present sea level. Moreover, X-ray diffraction, optical microscopy, mineralogy and major and trace element geochemistry of speleothems and clastic sediments found in the inner part of Selinitsa were also employed and combined to the aforementioned geomorphological data.&lt;/p&gt;&lt;p&gt;The objective of the study is to provide a model for the development and the paleoclimatic conditions of the Selinitsa Cave during Late Pleistocene, how sea-level affected the aforementioned system, and finally provide an estimate of sea-level fluctuation over the last 125 ka.&lt;/p&gt;

The Nesla Gorge and the connection of the Sofia Lake with the Pannonian Basin

The Nesla Gorge is a picturesque flat-bottomed gorge carved by the Gaber River through the limestones of the Slivnitsa Formation west of Nesla village, Dragoman area. Its flattened bottom is evidence for an inter-lake strait between the Gaber Basin and the Nishava-Moravian Basin in Serbia. This is proved by several layers in the Novi Iskar Formation containing mollusks typical of the Pannonian Basin. It is supposed that the main reason is the sea-level fluctuation of the Pannonian Sea due to Milankovitch climatic cycles which caused two-way movement of the water between the two basins through the Nesla Gorge. The geological history of the area, as evidenced by the geomorphological data, shows the important role of the Nesla Gorge for the existence of the Gaber Basin and Sofia Lake during the Pontian and Dacian Ages.

Carbonate-shelf evolution during the Oligocene to early Miocene: insights from shelf architecture, lithofacies, and depositional models of the Kujung Formation, offshore East Java, Indonesia

ABSTRACT Oligocene–Miocene carbonates are prolific hydrocarbon reservoirs in Southeast Asia. Extensive subsurface data for this stratigraphic section has become available through exploration and production activities. A carbonate shelf in the study area showed an evolution in shelf architecture and lithofacies during this period. Despite the economic importance, complexity, and data availability, there have been few published studies on a comprehensive description and interpretation of carbonate-shelf evolution in the region. We utilized data from nineteen wells and 1,300 km2 of 3D seismic data from offshore East Java to study the Oligocene–Miocene Kujung Formation. An average of 700 m stratigraphic sections from this formation were analyzed. This interval spans 13.5 million years (My) from the Rupelian, Chattian, through Aquitanian constrained by numerical ages from 87Sr/86Sr. The Kujung Formation is subdivided into the Rupelian–Chattian mixed-siliciclastic–carbonate shelf (MSCS) and the Aquitanian carbonate-buildups shelf (CBS) based on shelf architecture and lithofacies. The boundary between the MSCS and CBS is interpreted to be near the Oligocene–Miocene boundary at 23 Ma. Accumulation rates in the CBS are up to three times greater than that of the MSCS. We propose new depositional models for the Kujung Formation, which was used to discuss the dominant controls on shelf evolution. This study suggests that although climate played a role in dictating environmental conditions during the Oligocene–Miocene, the dominant factors controlling carbonate-shelf evolution in the study area appear to have been antecedent topography, routing of siliciclastic sediment, and patterns of sea-level fluctuation.

Analysis of moored ship oscillations in waves

В работе рассмотрены особенности колебаний пришвартованного судна для основных портов Сахалинской области, поскольку качка судна у причала может представлять опасность и приводить к повреждению судна или швартовых линий. По данным натурных измерений морского волнения в портовых бухтах рассчитаны спектры колебаний уровня и определены периоды существующих в них волн для диапазона периодов от 2 с до 30 минут. Произведен расчет периодов собственных колебаний (качки) двух типов судов, преимущественно швартующихся в портах. С учетом полученных результатов выполнено моделирование движения судов при волнении как динамической с системы внешним возбуждающим воздействием на основе дифференциального уравнения второго порядка. Показано влияние коэффициента вязкого демпфирования и жесткости швартовых на реакцию динамической системы без удара о причал и для режима ударного осциллятора. Установлено, что в случае прихода в район порта Корсаков длинноволновой зыби движения судна могут переходить в хаотические. The paper considers the peculiarities of moored vessel oscillations for the main ports of the Sakhalin region, since the pitching of the vessel at the berth can be dangerous and lead to damages of the vessel or mooring lines. Spectra of sea level fluctuations and periods of waves in port bays were calculated using sea level fluctuation measurements obtained in the range from 2 seconds to 30 minutes. Calculations of resonance periods (pitching) of two types of vessels mainly moored in ports were done. Taking into consideration these results the simulation of the vessel movement in waves as a dynamic system with an external excitation was performed on the base of second-order differential equation. The influence of viscous damping coefficient and mooring stiffness on the response of the dynamic system is shown for two cases: for system without impact and for the impact oscillator mode. It is established that in the event of a long-wave swell coming to the Korsakov port area, the vessels movements may become chaotic.