Integrated geophysical and geochemical assessment of submarine groundwater discharge in coastal terrace of Tiruchendur, Southern India

Submarine groundwater discharge (SGD) study is essential for groundwater in coastal terrace at Tiruchendur. The famous Murugan Temple is located in the area and around 25,000 people who visit this temple use the SGD well water at NaaliKinaru (a small open well) as holy water and drink it. The rock and soil type are sandy clay, silt, beach sand, calcarenite, kankar, gneissic rock and charnockite in base rock. Megascopic identification method was used to identify the porous and permeable rocks such as calcarenite, sandstone and kankar to support to increase SGD flux. Grain size study was used to identify the paleo-coastal estuarine environment with sediment deposits in the terrace. The square array electrical resistivity method was used to study the subsurface geology and aquifer depth. The 2d ERT technique was used to identify the subsurface shallow perched aquifer of freshwater. The magnetotelluric survey method was used to scan the entire subsurface geological and tectonic uplift, coastal ridges, rock folded subsurface structural features of continental and oceanic tectonism. Darcy’s law was used to calculate the SGD flux rate in the above study area.

PALEOGEOGRAPHIC PREREQUISITE FOR THE FORMATION OF THE GEOTECHNICAL CONDITIONS OF THE BLACK SEA HOLOCENE COASTAL TERRACE

The results of summary integral studies and analyzed references allow describing the geologic structure and paleographic formation conditions of the Caucasus Black Sea coast’s Holocene terraces, and reconstructing the spatialtemporal development picture of hydro- and lithodynamics processes caused current coastal geotechnical conditions.

Grasslands of the Sea of Japan coast (Lazovskiy nature reserve named after L. G. Kaplanov. Primorye Territory)

The study of grassland vegetation of the Sea of Japan coast in the Lazovskiy nature reserve (Primorye Territory, Russia) on the current sandy sea terraces is based upon the analysis of 110 relevés of coastal ve­getation obtained in 2009 at Zarya and Proselochnaya Bays (Fig. 1). The halophytic vegetation in supralittoral zone is formed under the influence of salinity from surges and pulverization. Communities belong to the class Honckenyo-Elymetea Tx. 1966, the order Hon­ckenyo majoris–Elymetalia mollis Ohba, Miyawaki et Tx. 1973, the alliance Senecioni pseudoarnicae–Leymion mollis Ohba, Miyawaki et Tx. ex Peinado et al. 2011 and the ass. Glehnio littoralis–Caricetum ma­crocephalae (Miyawaki 1967) Ohba, Miyawaki et Tx. 1973. This association is a pioneer stage of vege­tation development on sandy sea coast. The communities form a stripe of 15–150 m width on the offshore bar side exposed to sea. The association is typical for the continental coast of the Sea of Japan (Komarov, 1917; Kurentsova, 1969), southern Sakhalin (Stepanova, 1956) and northern part of Hokkaido Isl. (Ohba et al., 1973). Diagnostic species of ass. Glehnio littoralis–Caricetum macrocephalae (Table 1; Fig. 2) are obligate halophytes adaptated for growing on unstable sandy substrate (Carex macrocephala, Chorisis repens, Glehnia littoralis, Linaria japonica) The plant cover varies between 2 % and 70 %. Carex macrocephala and Leymus mollis are dominants. On the other offshore bar side with relatively ­stable substrate and grey sand soils, the glycophytic steppe-like grasslands with plants adapted to a moderate drought are developed. These communities include such coastal vascular plants as Festuca vorobievii, F. kolesnikovii, Dracocephalum charke­viczii, Oxytropis mandshurica, Plantago camtschatica, Carex gmelinii, and the others, while their floristic singularity is provided by 2 specific coastal grasses — Arundinella hirta and Koeleria tokiensis related to the meadow-steppe species Arundinella anomala and Koeleria cristata (Probatova, Seledets, 1999). Such grasslands are close to the steppe meadows of the alliance Arundinellion anomalae Akhtyamov et al. 1985 (the order Artemisietalia mandshuricae Akhtyamov et al. 1985, the class Arundinello anomalae–Agrostietea trinii Ermakov, Krestov 2009) in their composition (Akhtya­mov, 2000; Ermakov, Krestov, 2009) and high constancy values of diagnostic species of the forenamed alliance (e. g. Artemisia laciniata, A. manshurica, Dianthus chinensis). The presence of some xerophilous and meso-xerophilous species like Carex korshinskyi, Clematis hexapetala and Lespedeza juncea shows floristic relationships with dahurian steppes of the alliance Filifolion Akhtyamov ex Korolyuk 2002 (the class Cleistogenetea squarrosae Mirkin et al. ex Korotkov et al. 1991). For these grasslands, which have not been described within the J. Braun-Blan­quet approach, we suggest the preliminary alliance Festuco ovinae–Arundinellion hirtae all. nov. prov. with diagnostic species Festuca ovina s. l., Arundinella hirta, Dianthus chinensis, Artemisia manshurica, Viola mandshurica (Table 4, 5). Two association are described within it. Coastal steppe-like grasslands of the ass. Festuco ovinae–Arundinelletum hirtae ass. nov. hoc loco (Table 2, relevé 8–17; holotypus hoc loco — relevé 11) are deve­loped on the unstable substrate on psammozems with thin grey horizon on the reversal side of the offshore bar. At the sea side they border with the halophytic stands while on the opposite side the grasslands with closed cover are developed. The diagnostic species of the association are Festuca ovina s. l., Arundinella hirta, Dianthus chinensis, Artemisia manshurica, Viola mandshurica, Scutellaria strigillosa,dominants areusually Festuca ovina and Arundinella hirta.Plant covervaries between 7 % and 50 %. Mean height of herb layer is 25 cm; mean number of species amounts to 14 ± 4. Within the association we describe var. Juniperus davurica with prostrate Juniperus davurica and J. rigida (Fig. 3). These communities arelisted as the rare ones for the Amur Region (Krestov, Verkholat, 2002). Coastal grasslands of the ass. Koelerietum tokiensis ass. nov. hoc loco (Table 3, relevé 1–20; holotypus hoc loco — relevé 4) cover subhorizontal surface of the coastal terrace behind the offshore bar. Plant cover is 90 %; mean height of herb layer is 30–40 cm; the mean species number is 18 per sample plot of 25 m2. Diagnostic species are Koeleria tokiensis, Artemisia laciniata and Potentilla fragarioides. As the distance from the sea shore increases the community composition becomes more mesophilous. We propose 2 subassociations within this syntaxon. Grasslands of the subass. K. t. caricetosum lanceolatae subass. nov. hoc loco (Table 3, relevé 1–10; holotypus hoc loco — relevé 4) are widely spread on the coastal terraces. Diagnostic species are Carex lanceolata and Lespedeza juncea. Communities of the subass. K. t. artemisietosum stoloniferae subass. nov. hoc loco (Table 3, relevé 11–20; holotypus hoc loco — relevé 17; Fig. 4) occur at the fringe of the terraces and border on oak forests. Diagnostic species are Artemisia stolonifera, Pteridium aquilinum, Solidago pacifica, Lupinaster pacificus, Hieracium umbellatum, Galium verum and Cirsium vlassovianum. The described syntaxa form a spatial and temporal range due to the coastal terrace changes and shifts in the environmental conditions at a distance from the sea (Fig. 5–8). Under the humid climate the peculiar grasslands with mesoxerophytes are the specific features of the accumulative sea terraces in southern part of the Amur region. This peculiarity demonstrates phytogeographical relations between the coastal vegetation and the continental arid communities of the Central Asia and is likely to be a regional feature of the South Sikhote-Alin plant cover.

Notes on the sea caves of sub-Antarctic Macquarie Island, Southern Ocean

ABSTRACTCaves of marine origin occur in tectonically uplifted stacks on the coastal terrace and in plateau edge cliffs at a number of locations around Macquarie Island. Some of the caves have been located and their distributions mapped. Four of the best known caves are mapped in detail. Aspects of their geology, structure and biology, including speleothem development, clastic deposits, faunal remains and subfossil deposits are explored. Many of these caves contain deposits, which may have the potential to be investigated, as beach and peat deposits have been, for dating key time periods in the island's evolution. The palaeoenvironmental research potential of the sea caves on Macquarie Island has yet to be exploited. Further knowledge about these caves will assist in the understanding of the processes that have acted on Macquarie Island and other polar and sub-polar islands.