Mineralogy and petrographic summary of ODP Leg 198 sites and DSDP Hole 62-463, Shatsky Rise

This petrological study of the lower Aptian Oceanic Anoxic Event (OAE1a) focused on the nature of the organic-rich interval as well as the tuffaceous units above and below it. The volcaniclastic debris deposited just prior to the OAE1a is consistent with reactivation of volcanic centers across the Shatsky Rise, concurrent with volcanism on the Ontong Java Plateau. This reactivation may have been responsible for the sub-OAE1a unconformity. Soon after this volcanic pulse, anomalous amounts of organic matter accumulated on the rise, forming a black shale horizon. The complex textures in the organic-rich intervals suggest a history of periodic anoxia, overprinted by bioturbation. Components include pellets, radiolarians, and fish debris. The presence of carbonate-cemented radiolarite under the OAE1a intervals suggests that there has been large-scale remobilization of carbonate in the system, which in turn may explain the absence of calcareous microfossils in the section. The volcanic debris in the overlying tuffaceous interval differs in that it is significantly epiclastic and glauconitic. It was likely derived from an emergent volcanic edifice.

(Table 4) Mineralogy at DSDP Leg 55 Holes

On Leg 55, cores were takenfrom three seamounts in the Emperor Seamount chain: Ojin, Nintoku, and Suiko Seamounts. At the drilling sites the water depth was 1300 to 1700 meters; the maximum thickness of the sediment column was 180 meters at Site 433.

Mineralogical assemblage in sediment core GeoB12309-5 and in area samples from the Makran subduction zone

In order to study late Holocene changes in sediment supply into the northern Arabian Sea, a 5.3 m long gravity core was investigated by high-resolution geochemical and mineralogical techniques. The sediment core was recovered at a water depth of 956 m from the continental slope off Pakistan and covers a time span of 5 kyr. During the late Holocene source areas delivering material to the sampling site did, however, not change and were active throughout the year.

Metabolic rates and tissue composition of the coral Pocillopora verrucosa over 12 latitudes in the Red Sea characterized by strong temperature and nutrient gradient

Global warming was reported to cause growth reductions in tropical shallow water corals in both, cooler and warmer, regions of the coral species range. This suggests regional adaptation with less heat-tolerant populations in cooler and more thermo-tolerant populations in warmer regions. Here, we investigated seasonal changes in the in situ metabolic performance of the widely distributed hermatypic coral Pocillopora verrucosa along 12 degrees latitudes featuring a steep temperature gradient between the northern (28.5 degrees N, 21-27 degrees C) and southern (16.5 degrees N, 28-33 degrees C) reaches of the Red Sea. Surprisingly, we found little indication for regional adaptation, but strong indications for high phenotypic plasticity: Calcification rates in two seasons (winter, summer) were found to be highest at 28-29 degrees C throughout all populations independent of their geographic location. Mucus release increased with temperature and nutrient supply, both being highest in the south. Genetic characterization of the coral host revealed low inter-regional variation and differences in the Symbiodinium clade composition only at the most northern and most southern region. This suggests variable acclimatization potential to ocean warming of coral populations across the Red Sea: high acclimatization potential in northern populations, but limited ability to cope with ocean warming in southern populations already existing at the upper thermal margin for corals

Trace and rare elements and factors at DSDP Hole 71-511

The distribution of paragenetic assemblages of trace and rare elements, as revealed by factor analysis (R-mode, Q-mode), the ratios of elements to Zr and the interpretation of these data in the context of the known mineralogy, lithology, and geology of the region, provide the bases for the outline of the geochemical history of sedimentation in the study area that forms the subject of this chapter. Two stages may be discerned. 1. Late-Middle Jurassic-Early Cretaceous (160-106? Ma). The sediments that accumulated in relatively shallow water (shelf) were predominantly clay, with dispersed sapropelic organic matter, plant fragments, pyrite, admixtures of acid-medium volcanic glass, and epigenetic crystals of gypsum. The bottom water layers of the basin are notably stagnant. The sediments are characterized by higher amounts of V, Zn, Cu, Cr, Rb, and Be associated with organic matter. Lower Cretaceous sediments, separated from those of the Upper Jurassic by a hiatus, accumulated in a deepened and enlarging basin. These Lower Cretaceous deposits are chemically similar to those of the Upper Jurassic, but contain diagenetic concentrations of Zn, Ni, and La. 2. Early-middle Albian (Unit 5)-middle Maestrichtian (1067-66.6Ma). The prevailing regime was that of an open ocean basin that tended to expand and deepen. During the second half of the early-middle Albian, the biogenic components Ba, Sr, and CaCO3 accumulated. By the end of this interval, Ti/Zr values had increased. In conjunction data on mineral composition, they testify to an outburst of basaltoid volcanism related to tectonic activity before an erosional hiatus (late Albian-Cenomanian). At the end of the Cenomanian-Turonian, residual deposits of predominantly clay sediments with relatively high amounts of Ti and Zr and associated rare alkalis (Li, Rb) accumulated. Clay sediments deposited during the Coniacian-Santonian were characterized by higher concentrations of Ti, Zr, Li, and Rb, by diagenetic carbonate phases of Ni, Zn, and La, and by sulphides and Fe-oxides with an admixture of Ni and Co. The latter half of the interval saw the deposition of fine basaltoid volcanoclastic material, diagenetically altered by zeolitization and carbonatization and enriched with Se, Pb, Ti, Sr, Ba, Y, and Yb. Sediments with a similar chemistry accumulated in the Campanian-middle Maestrichtian. Strong current activity preceding a global hiatus at the Mesozoic/Cenozoic boundary is reflected in both lower sedimentation rates and the presence of higher residual concentrations of Ti, Zr, Ba, Sr, and other elements studied in this chapter.

Heavy and light minerals at DSDP Leg 67 Holes

Heavy and light minerals were examined in 29 samples from Sites 494, 498, 499, 500, and 495 on the Deep Sea Drilling Project Leg 67 Middle America Trench transect; these sites represent lower slope, trench, and oceanic crust environments off Guatemala. All samples are Quaternary except those from Hole 494A (Pliocene) and Hole 498A (Miocene). Heavy-mineral assemblages of the Quaternary sediments are characterized by an immature pyroxene-amphibole suite with small quantities of olivine and epidote. The Miocene sediments yielded an assemblage dominated by epidote and pyroxene but lacking olivine; the absence of olivine is attributed to selective removal of the most unstable components by intrastratal solution. Light-mineral assemblages of all samples are predominantly characterized by volcanic glass and plagioclase feldspar. The feldspar compositions are compatible with andesitic source rocks and frequently exhibit oscillatory zoning. The heavy- and light-mineral associations of these sediments suggest a proximal volcanic source, most probably the Neogene highland volcanic province of Guatemala. Sand-sized components from Site 495 are mainly biogenic skeletons and volcanic glass and, in one instance (Section 495-5-3), euhedral crystals of gypsum.

Descriptions, isotopes and minerals of sediments at DSDP Leg 64 Holes

Mineralogical and oxygen isotopic analyses of samples from Deep Sea Drilling Project Sites 477, 481, and 477 in the Guaymas Basin indicate the existence of two distinct hydrothermal systems. In the first, at Sites 481 and 478, hot dolerite sills intruded into highly porous hemipelagic siliceous mudstones that were moderately rich in organic matter, thermally altered the adjacent sediments, and expelled hydrothermal pore fluids. The second, at Site 477 and active at present, is most probably caused by a recent igneous intrusion forming a magma chamber at shallow depth. In the first hydrothermal system, the main thermal reactions above and below the sills are dissolution of opal-A and formation of quartz, either directly or through opal-CT; formation of smectite; formation of analcime only above the sills; dissolution and recrystallization of calcite and occasional formation of dolomite or protodolomite. The d18O values of the hydrothermally altered sediments range from 9.9 to 12.2 per mil (SMOW). The d18O values of recrystallized calcites above the first sill complex, Site 481, indicate temperatures of 140° to 170°C. No fluid recharge is required in this system. The thickness of the sill complexes and the sequence and depth of intrusion into the sediment column determine the thickness of the alteration zones, which ranges from 2 or 3 to approximately 50 meters. Generally, the hydrothermally altered zone is thicker above than below the sill. In the second type, the sediments are extensively recrystallized. The characteristic greenschist-facies mineral assemblage of quartz-albite-chlorite-epidote predominates. Considerable amounts of pyrite, pyrrhotite, and sphene are also present. The lowest d18O value of the greenschist facies rocks is 6.6 per mil, and the highest d18O value of the associated pore fluids is +1.38 per mil (SMOW). The paragenesis and the oxygen isotopes of individual phases indicate alteration temperatures of 300 ± 50°C. On the basis of the oxygen isotopes of the solids and associated fluids, it is concluded that recharge of fluids is required. The water/rock ratio in wt.% is moderate, approximately 2/1 to 3/1 - higher than the calculated water/rock ratio of the hydrothermal system at the East Pacific Rise, 21 °N.

Composition of Messinian sediments from the Tyrrhenian Sea

The data base for this study is represented by essentially nonevaporitic Messinian sediments recovered at ODP Sites 654, 653, 652, and 656 along the eastern Sardinian margin, and of the overlying early Pliocene oozes. Grain-size distribution, carbonate content, and microscopic observation of the sand size fractions were investigated. Messinian paleoenvironments, documented in the western Tyrrhenian Sea (ODP Sites 654 and 653), provide additional evidence supporting the deep basin desiccation model. A sharp lithologic contrast between early Pliocene pelagic oozes and latest Messinian conformable gypsiferous silts supports this model. The "lago-mare" biofacies was only occasionally observed in the shallowest site and is limited to the topmost part of the Messinian. Sites 652 and 656, lying in the deeper part of the Tyrrhenian and located on the downthrown side of an important eastward dipping fault system known as "Faglia centrale" are characterized by terrigenous sedimentation, with partly recycled minor evaporites. Of special interest is Site 652, where the thickness of the (probable) Messinian is 530 m. Sedimentary characters indicate a permanently subaqueous but nonmarine environment, with turbidites accumulating in a rapidly subsiding basin. According to the model proposed, this basin was fed by continental waters during times of maximum evaporitic draw-down, with temporary marine incursions from the west or southwest when the water level was higher. A basement ridge separated the evaporating pond from this endoreic lake located on the opposite (eastern) margin of the Tyrrhenian Basin, which was then limited to its western part. Post-Messinian reactivation of the "Faglia centrale" is necessary to account for the inversion of the relief.

Mineralogy and geochemistry at DSDP Leg 64 Holes

At DSDP Site 477, late Quaternary diatomaceous muds and delta-derived silty-sand turbidites at 2000 meters water depth have been extensively and progressively altered by a deep-seated heat source beneath a sill. Bulk petrologic and microprobe analyses have identified a crudely zoned paragenesis within 260 meters sub-bottom which ranges from unaltered to slightly altered oozes (0-50 m), anhydrite-dolomite claystones (105-125 m), illite-chlorite-pyrite claystones (125-140 m), chlorite-pyrite-calcite-carbonaceous claystones with traces of K-feldspar, albite, epidote (140-190 m), and chlorite-epidote-quartz-albite-pyrrhotite-sphene sandstone (190-260 m). Several petrologic features suggest rapid processes of ocean floor metamorphism: (1) friable and porous textures, (2) abundant relict grains with overgrowths, (3) idiomorphic habits on epidotes, feldspars, and quartz, and (4) a steep gradient in levels of alteration. Many aspects of this hydrothermal assemblage are similar to hydrothermally metamorphosed sandstones of the Cerro Prieto, Mexico, geothermal area.

Petrographic description and mineral composition of ODP Site 161-975 sediments

Ocean Drilling Program Site 975 is located near the base of the Menorca Rise in the South Balearic Basin of the western Mediterranean Sea. Coring at this site penetrated the Pliocene/Miocene boundary and recovered a sequence of sediments that represent the final stages of salt deposition and the transition from evaporitic to open marine conditions at the end of the Miocene (Messinian). Detailed petrographic observations and bulk mineralogical analyses by X-ray diffraction form the basis for preliminary interpretations of depositional environments for this section. Gypsum is thought to have been deposited in an evaporating basin below wave base. Cycles consisting of a clay layer overlain by gypsiferous chalk, laminated gypsum, and finally pinch-and-swell gypsum suggest upsection increases in salinity. The gypsum section is overlain by two exotic sand layers thought to mark events of fresher water (marine or meteoric) inflow to the basin. Gypsum deposition terminated and was replaced by inorganic precipitation of micritic calcite with periodic, variable dilution by fine-grained terrigenous sediment. The micritic sediments have fine, slightly wavy, laminations indicating either an algal/microbial mat origin, or varve-like fluctuations in deposition, perhaps in a deep basin. The Pliocene/Miocene boundary falls within an interval of banded micritic silty clays that reflect the final environmental fluctuations during the transition to the open marine conditions of the Pliocene.

Bulk composition and clay mineralogy at DSDP Legs 56 and 57

Altogether 513 samples from sediments of Cretaceous to Pleistocene age from DSDP Legs 56 and 57 were examined by x-ray methods. The main constituents are clay minerals, quartz, feldspar, opaline silica, and volcanic glass. The sediment composition reflects the position of the sites in relation to the main source area, the Japanese Island Arc. For example, relatively coarse-grained material rich in quartz and feldspar was deposited closest to the islands, whereas finer-grained material rich in clay minerals (mainly smectite and illite, with lesser amounts of kaolinite and chlorite) was deposited farther seaward. Vertical fluctuations in the composition of the sediments show the same trend in all sites and are caused mainly by a fluctuating contribution of biogenic silica with time. A trend reversal in the chlorite/kaolinite ratio at Site 438 supports the conclusion that the subsidence of the Oyashio ancient landmass took place during the middle Miocene. That ratio also indicates a northwest drift in the position of Site 436 by sea floor spreading. Oscillations of the illite/smectite ratio during the Pleistocene at Site 436 show the variations of climate during this period. During early diagenesis potassium is fixed in smectite. With increasing depth of burial a smectite-illite mixed layer is formed, with increasing illite layering. At Sites 434, 440, and 441, stepwise changes confirm intensive tectonic process at the midslope terrace and the lower inner slope of the Japan Trench.

(Supplement) Groundwater quality in Lahore Pakistan: emphasis on Arsenic and Fluoride levels

The dataset provides detailed information on the study that was conducted in Lahore's 7 major towns. The sample was taken from 472 tubewells and analyzed for major cations and anions using APHA 2012 techniques as explained herein. Besides, E.coli determination was done to check for microbial contamination. The data includes results from PHREEQC modeling of As(III)/ As(V) species and saturation indices as well as Aquachem's computed hydrochemical water facies. The WHO (2011) and EPA standards included in Aquachem identified the parameters that where in violation. Bicarbonates dominated the groundwater types with 50.21% of the samples exceeding the EPA maximum permissible limit of 250 mg/L in drinking water. Similarly, 30.51% of the samples had TDS values greater than 500 mg/L while 85.38 % of the samples exceed 10 µg/L threshold limit value of arsenic. Also, instances of high magnesium hazard values were observed which requires constant assessment if the groundwater is used for irrigation. Higher than 50% MH values are detrimental to crops which may reduce the expected yields. The membrane filtration technique using m-Endo Agar indicated that 3.59% samples had TNC (too numerous to count) values for E.coli while 5.06% showed values higher than 0 cfu/ 100 ml acceptable value in drinking water. Any traces of E-coli in a groundwater sample indicate recent fecal contamination. Such outcomes signify presence of enteric pathogens. If the groundwater is not properly dosed with disinfectants it may cause harm to human health. It is concluded that more studies are needed and proper groundwater management implement to safeguard the lives of communities that depend solely on groundwater in the city.