Wyniki wyszukiwania - BazTech

1

Geochemistry of surface sediments from the northwestern Gulf of Mexico : implications for provenance and heavy metal contamination

Armstrong-Altrin John S., Botello Alfonso V., Villanueva Susana F., Soto Luis A.

Geological Quarterly

|

2019

|

Vol. 63, No. 3

522--538

EN

Thirty-five near-surface sediment samples were recovered from the continental shelf and upper slope regions of the north-western (NW) Gulf of Mexico. The geochemical data of the sediments recovered were examined to investigate the weathering intensity, provenance, palaeo-oxygenation condition, and level of heavy metal contamination. The sediments analysed showed a moderate to high intensity of chemical weathering. Major and trace element concentrations indicated a terrigenous origin, closely related to the weathering of rocks rich in aluminosilicates. The results of this study further revealed that major rivers, the Bravo and Soto La Marina, played an important role in delivering sediments to the study area. The concentration of transition trace elements such as Cr, Cu, Ni, and V revealed that the sediments were derived from intermediate rocks such as andesite. The V/Cr, Ni/Co, and Cu/Zn ratios in the sediments were <2, <5, and <1, respectively, suggesting a depositional process occurred under well-oxygenated conditions. Principle Component Analysis (PCA) did not show a significant difference in sediment texture between the continental shelf and slope areas. The enrichment factor (EF) and Geo-accumulation index (lgeo) values were <2 and <1, respectively, suggesting the absence of an anthropogenic input.

2

Spherical, magnetic grains of extraterrestrial origin, isolated from Pacific sediments

Uścinowicz G.

Oceanological and Hydrobiological Studies

|

2012

|

Vol. 41, No. 3

48-53

EN

The aim of this study was to determine the existence of cosmic spherules in oceanic sediments. Two cores recovered from the Clarion-Clipperton fault zone (northeastern Pacific Basin) contain magnetic spherules of extraterrestrial origin. Their chemical compositions and morphological features show the degree of heterogeneity of cosmic material reaching the earth’s surface. The diverse origins of spherules from the Pacific Ocean explains their diverse composition and does not allow for the classification of the material into a single group. In addition, the time interval over which sediments accumulated extends for an estimated period of approximately 200 000 years to the present.

3

A framework of ichthyofaunal ecostratigraphy of the Oligocene-Early Miocene strata of the Polish Outer Carpathian basin

Kotlarczyk J., Jerzmańska A., Świdnicka E., Wiszniowska T.

Annales Societatis Geologorum Poloniae

|

2006

|

Vol. 76, No 1

1-111

EN

The paper presents the results of an analysis of ichthyofaunal variability throughout the section of the Menilite-Krosno Series (MKS) in the Outer Carpathians of Poland. The studied tanathocoenoses were formed at the bottom of a more than 2,000 m deep northern basin of the Tethys, being largely represented by the continental rise and bottoms of its narrow furrows, and - to a lesser degree - the continental slope and slopes of a submarine high. Lateral variability of statististically representative assemblages of tanathocoenoses hosted in thin, isochro- nous horizons is interpreted as a result of both local changes of ichthyocoenoses and the influence of post-mortem relocation of fishes that mainly dwelled the shelf and upper continental slope. Vertical variability, in turn, is considered as a resulting from changeable conditions of the ecological environment, the input and outflow of taxa whose evolution proceeded in the Indo-Pacific area, and the species extinction. Changeability of ichthyofauna within a ca. 16-m.y.-long interval made it possible to document and formally describe 9 zones and 4 subzones of ichthyofauna of ecostratigraphic character. These zones comprise index, representative and accompanying taxa that belong to different ecological groups. Conceptual models of the origin of ichthyofaunal assemblages of individual zones are presented. It is suggested that the origin of assemblage differentiation resulted from the appearance and disappearance of the oxygen minimum zone in the water column, global and local sea level changes, topography of the basin bottom, as well as final basin infilling by sediments of submarine fans. The described and preserved collection of fossil Carpathian fishes, housed at the Department of Palaeozoology of the University of Wrocław, requires further specialized palaeontological studies in order to reconstruct a more complete composition of the Oligocene-Early Miocene ichthyofauna.

4

Mineralogy of deep-sea sediments around Reunion Island (Western Indian Ocean)

Duczmal-Czernikiewicz Agata, Lorenc Stanisław, Stattegger Karl

Geologos

|

2003

|

Vol. 6

9--56

EN

Detailed petrographic and mineralogical analyses were performed in order to determine and classify ocean sediments in the vicinity of Reunion Island. Surface sediments from the ocean floor and samples from cores of thickness down to 560 cm were classified as hemipelagic muds of volcanogenic origin, pelagic calcareous oozes and basaltic breccia. Heavy, light and pelitic fractions were investigated separately. Basaltic breccia consists of rock fragments and glass shards. Hemipelagic muds consist mostly of basaltic fragments, plagioclases, pyroxenes and olivines, basaltic glass shards, zeolites, and clay minerals. Moreover, various amounts of carbonate and siliceous bioclasts also occur. Pelagic oozes (nannoplankton and foraminifera) are composed mainly of carbonate bioclasts and micrite. The mineral composition of the sediments and the relationship between pelagic and volcanogenic components were determined referring to the depth and distance from the Reunion Island. The sediments from the southernmost profile are different than others taken at a smaller distance from the island not only with respect to the fossil assemblage but also with respect to the occurrence of concretions (and quartz, staurolite and apatite) and greater degree of glass alteration. These sediments were formed under the conditions of pelagic sedimentation, and so the slow sedimentation rate facilitated the formation of concretions. The mineral composition of the sediments differs according to the distance from the volcanic Reunion Island and the depth from which the sediment was sampled.

PL

Przedmiotem badań była charakterystyka osadów z rejonu wyspy Reunion na podstawie szczegółowej analizy petrograficznej i mineralogicznej. Osady z dna oceanu oraz rdzenie o długości do 560 cm (150 próbek) zostały zaklasyfikowane jako: hemipelagiczne muły wulkanogeniczne, pelagiczne muły węglanowe (nannoplanktonowe i otwornicowe) oraz wulkanogeniczna brekcja bazaltowa. Brekcję bazaltową tworzą okruchy skal bazaltowych i szkliwa wulkanicznego. Muły wulkanogeniczne składają się głównie z fragmentów skał bazaltowych, minerałów pochodzenia wulkanicznego (plagioklazów, piroksenów i oliwinów), okruchów szkliwa wulkanicznego, zeolitów oraz minerałów ilastych. Ponadto występują w zmiennych ilościach bioklasty węglanowe i podrzędnie krzemionkowe. Muły pelagiczne są utworzone głównie z bioklastów węglanowych oraz mikrytu. Skład mineralny oraz wzajemne relacje składników pelagicznych i wulkanogenicznych osadu są zdeterminowane głębokością i położeniem punktów badawczych względem wyspy. Osady z profilu położonego najbardziej na SE różnią się od innych położonych bliżej wyspy nie tylko zespołem skamieniałości, ale również występowaniem konkrecji (także kwarcu, staurolitu i apatytu) oraz większym stopniem przeobrażenia szkliwa wulkanicznego. Osady te powstawały w warunkach sedymentacji pelagicznej oraz powolnym tempem sedymentacji wyznaczonym przez formowanie się konkrecji. Skład mineralny osadów zależy od odległości od wulkanicznej wyspy Reunion oraz od głębokości, z której osad był pobrany.