Sediment texture, carbonate content, and carbonate mineralogy of ODP Holes 182-1130A and 182-1132B

At Sites 1130 and 1132 of Ocean Drilling Program Leg 182 in the Great Australian Bight, we recovered an expanded Pleistocene section dominated by packstone and wackestone, deposited at unusually high rates of >20 cm/k.y. Shipboard observations detected an intermittent meter-scale alternation of light gray intervals with olive-gray intervals. Meter-scale samples were collected from the upper 250 m at both sites and decimeter-scale samples from four selected 2.5- to 4.0-m intervals in order to determine the texture and composition of sediments deposited along the upper slope throughout the Quaternary. Detailed textural and compositional data are presented from a total of 540 samples collected from both sites. Results indicate a general coarsening upward at both sites, with an accompanying upcore increase in high-Mg calcite (HMC) and aragonite and a decrease in low-Mg calcite (LMC). Samples collected at decimeter-scale intervals substantiate that the alternating light gray and olive-gray units detected on board ship are lithologically distinct. Light gray units consist of an LMC-rich silt, whereas olive-gray units consist of an aragonite and HMC-rich sand and silt. Sediment sources as well as timing and controls of this cyclic depositional pattern will be the subject of further investigations.

Selective destructive demagnetization of breccias from DSDP Hole 83-504B

The magnetization of four breccia samples from the Leg 83 section of DSDP Hole 504B was analyzed by selective destructive demagnetization in order to study the origin and stability of hydrothermally altered basalts. The NRM directions of the clasts for three of the four samples are randomly oriented and much more strongly magnetized than the bulk sample. Clasts which were individually demagnetized show two or more components of magnetization, but neither are coincident with those of the bulk sample, indicating that NRM was probably acquired prior to the consolidation of the breccia and suggesting that any overprint (VRM or otherwise) can be removed by AF demagnetization to at most 50 Oe. Reflected light microscopy and electron microprobe analysis of two samples show that the unexpectedly high NRM of the matrix regions is apparently the result of secondary magnetic phases precipitated from hydrothermal solutions.

High-resolution sedimentological and paleontological record of ODP Site 167-1019

Holocene and latest Pleistocene oceanographic conditions and the coastal climate of northern California have varied greatly, based upon high-resolution studies (ca. every 100 years) of diatoms, alkenones, pollen, CaCO3%, and total organic carbon at Ocean Drilling Program (ODP) Site 1019 (41.682°N, 124.930°W, 980 m water depth). Marine climate proxies (alkenone sea surface temperatures [SSTs] and CaCO3%) behaved remarkably like the Greenland Ice Sheet Project (GISP)-2 oxygen isotope record during the Bølling-Allerod, Younger Dryas (YD), and early part of the Holocene. During the YD, alkenone SSTs decreased by >3°C below mean Bølling-Allerod and Holocene SSTs. The early Holocene (ca. 11.6 to 8.2 ka) was a time of generally warm conditions and moderate CaCO3 content (generally >4%). The middle part of the Holocene (ca. 8.2 to 3.2 ka) was marked by alkenone SSTs that were consistently 1-2°C cooler than either the earlier or later parts of the Holocene, by greatly reduced numbers of the gyre-diatom Pseudoeunotia doliolus (<10%), and by a permanent drop in CaCO3% to <3%. Starting at ca. 5.2 ka, coastal redwood and alder began a steady rise, arguing for increasing effective moisture and the development of the north coast temperate rain forest. At ca. 3.2 ka, a permanent ca. 1°C increase in alkenone SST and a threefold increase in P. doliolus signaled a warming of fall and winter SSTs. Intensified (higher amplitude and more frequent) cycles of pine pollen alternating with increased alder and redwood pollen are evidence that rapid changes in effective moisture and seasonal temperature (enhanced El Niño-Southern Oscillation [ENSO] cycles) have characterized the Site 1019 record since about 3.5 ka.

Diatom stratigraphy of ODP Leg 150 holes

Diatoms are present in middle to lower upper Miocene sections of all holes examined during Leg 150, but are generally absent or in low abundance in Pleistocene to middle upper Miocene sediments. An exception is the alternating diatom-rich, diatom-poor intervals in upper Quaternary sediments. Five new diatom zones, covering an interval from near the lower/middle Miocene boundary to the lower upper Miocene, are proposed. Some of the taxon used to define these zones are also used in zonal schemes for the East Coast of the United States, and allow for correlations to be drawn between this region and Leg 150 sites. Lower Miocene and older levels are not included in this study. Although older Tertiary diatoms are present at some of the sites, dissolution has largely compromised their usefulness as zonal markers.

Isotopic and chemical compositions of DSDP site 18-174 sediments

The Astoria submarine fan, located off the coast of Washington and Oregon, has grown throughout the Pleistocene from continental input delivered by the Columbia River drainage system. Enormous floods from the sudden release of glacial lake water occurred periodically during the Pleistocene, carrying vast amounts of sediment to the Pacific Ocean. DSDP site 174, located on the southern distal edge of the Astoria Fan, is composed of 879 m of terrigenous sediments. The section is divided into two major units separated by a distinct seismic discontinuity: an upper, turbidite fan unit (Unit I), and an underlying finer-grained unit (Unit II). Both units have overlapping ranges of Nd and Hf isotope compositions, with the majority of samples having e-Nd values of -7.1 to -15.2 and eHf values -6.2 to -20.0; the most notable exception is the uppermost sample in the section, which is identical to modern Columbia River sediment. Nd depleted mantle model ages for the site range from 2.0 to 1.2 Ga and are consistent with derivation from cratonic Proterozoic source regions, rather than Cenozoic and Mesozoic terranes proximal to the Washington-Oregon coast. The Astoria Fan sediments have significantly less radiogenic Nd (and Hf) isotopic compositions than present day Columbia River sediment (e-Nd=-3 to -4; [Goldstein, S.J., Jacobsen, S.B., 1987. Nd and Sr isotopic systematics of river water suspended material: implications for crustal evolution. Earth. Planet. Sci. Lett. 87, 249-265; doi:10.1016/0012-821X(88)90013-1]), and suggest that outburst flooding, tapping Proterozoic source regions, was the dominant sediment transport mechanism in the genesis and construction of the Astoria Fan. Pb isotopes form a highly linear 207Pb/204Pb - 206Pb/204Pb array, and indicate the sediments are a binary mixture of two disparate sources with isotopic compositions similar to Proterozoic Belt Supergroup metasediments and Columbia River Basalts. The combined major, trace and isotopic data argue that outburst flooding was responsible for depositing the majority (top 630 m) of the sediment in the Astoria Fan.

Late Quaternary carbonate and isotope stratigraphy of DSDP Site 90-594 east of South Island, New Zealand

The late Quaternary sequence off eastern South Island, New Zealand, consists of ~100 m of alternating bluish gray pelagic oozes and greenish gray hemipelagic oozes that extend uninterruptedly back to the Brunhes/Matuyama boundary (0.73 m.y.). A very high resolution (~2400 yr.) record of sediment texture, calcium carbonate content, and planktonic and benthic foraminiferal oxygen and carbon isotope composition demonstrates an in-phase cyclical fluctuation between the sedimentary parameters that closely correspond to the pelagic-hemipelagic sedimentation cycles and the isotope composition. Pelagic oozes, formed during interglacial periods of high eustatic sea level, are characterized by calcareous microfossils, relative enrichment in sand and clay sizes, high carbonate contents, reduced delta18O values, and increased delta13C values. Hemipelagic oozes, associated with glacial episodes and lowered eustatic sea level, include common terrigenous material and siliceous microfossils, are enriched in silt sizes, have low carbonate contents, high delta18O values, and low delta13C values. The history of alpine glaciations and associated erosion of the South Island of New Zealand, as expressed by the appearance of hemipelagic oozes, can be correlated directly with the major fluctuations of Northern Hemisphere ice sheets as expressed by the influence of eustatic sea-level changes on the oxygen isotope composition of both planktonic and benthic foraminifers. This high-accumulation-rate record contains conspicuous intervals of highfrequency, high-amplitude isotope variability including the presence of multiple glacial/interglacial intervals within single isotope stages, and offers one of the best sections cored to date for detailed study of the evolution and history of climate change over the last 0.75 m.y.

Magnetic properties of gabbros from ODP Hole 118-735B

A total of 500.7 m of continuous, vertical, oceanic gabbroic section was recovered during Leg 118. The gabbros obtained exhibited various degrees of alteration and deformation, which gave us a good opportunity to study the magnetic properties of oceanic gabbros. Many of these gabbros, which are mainly Fe-Ti oxide gabbros, have strong and unstable secondary magnetic components that were acquired during drilling. Stable inclinations, which are probably in-situ magnetic directions, show a single polarity, with an average value of 66° (±5°), meaning that the studied 501-m oceanic gabbroic block may be a candidate for the source of the marine magnetic anomaly. This may also imply that the metamorphism of oceanic gabbros causing acquisition of magnetization probably occurred within one geomagnetic polarity chron (about 0.3 to 0.7 m.y.) after these gabbros formed at the ridge, leading us to conclude that oceanic gabbros record the so-called Vine-Matthews-Morley type of initial magnetization at the ridge. The average intensity value of stable magnetic components of individual samples, which may be a minimum estimate for remanent magnetizations, is 1.6 A/m. Assuming this magnetic intensity value and a uniform magnetization within an oceanic gabbroic layer having a thickness of 4.5 km (i.e., whole layer 3), it is possible to explain most of the marine magnetic anomaly. If magnetic properties of the samples obtained from Hole 735B are common to oceanic gabbros, layer 3 may contribute more significantly to seafloor spreading magnetic anomalies than previously thought.

Spatiotemporal monitoring of water quality in coral reefs of Tayrona National Natural Park, Colombian Caribbean, 2011-2013

Tayrona National Natural Park (TNNP; 11°17' - 11°22' N and 73°53' - 74°12' W) is a hotspot of coral reef biodiversity in the Colombian Caribbean, located between the city of Santa Marta (>455,000 inhabitants) and several smaller river mouths (Rio Piedras, Mendihuaca, Guachaca). The region experiences a strong seasonal variation in physical parameters (temperature, salinity, wind, and water currents) due to alternating dry seasons with coastal upwelling and rainy seasons. Here, a range of water quality parameters relevant for coral reef functioning is provided. Water quality was measured directly above local coral reefs (~10 m water depth) by a monthly monitoring for up to 25 months in the four TNNP bays (Chengue, Gayraca, Neguanje, and Cinto) and at sites with different degree of exposition to winds, waves and water currents (exposed vs. sheltered sites) within each bay. The water quality parameters include: inorganic nutrient (nitrate, nitrite and soluble reactive phosphorus), chlorophyll a, particulate organic carbon and nitrogen concentrations (with a replication of n=3) as well as oxygen availability, biological oxygen demand, seawater pH, and water clarity (with a replication of n=4). This is by far the most comprehensive coral reefs water quality dataset for the region. A detailed description of the methods can be found within the referenced publications.

Geological investigation of dykes in Shackleton Range, Antarctica

During the Geological Expedition to the Shackleton Range, Antarctica (GEISHA) in 1987/88, samples were taken from twenty-one basaltic dykes for palaeomagnetic investigations. The directions of characteristic remanent magnetization (ChRM) of the dykes were determined by thermal and alternating-field demagnetization of 268 cores drilled from the specimens collected. Moreover, on account of the hydrothermal and sometimes low-grade metamorphism of the dyke rock and the resulting partial modification of the primary magnetization, not only were comprehensive magnetic studies carried out, but also ore-microscopic examination. Only thus was it possible to achieve a reasonable assessment and interpretation of the remanent magnetization. Jurassic and Silurian-Devonian ages were confirmed for the dykes of the northern and northwestern Shackleton Range by comparison of the paleopole positions calculated on the basis of the ChRM of the dykes with the known pole positions for the eastern Antarctic, as well as with polar-wandering curves for Gondwana. Radiometric ages were also determined far some of the dykes. Middle and Late Proterozoic ages are postulated far the dykes in the Read Mountains. Conclusions on the geotectonic relations of the Shackleton Range can also be drawn from the palaeomagnetic data. It has been postulated that the main strike direction, which differs distinctly from that of the Ross orogen, is due to rotation or displacement of the Shackleton Range crustal block; however, this was not corroborated. The pole positions for the Shackleton Range agree with those of rocks of the same age from other areas of East Antarctica and its positions in the Palaeozoic-Mesozoic polar-wandering path for Gondwana are evidence against the idea of rotation and rather suggest that the position of the Shakleton Range crustal block is autochthonous.

Magnetic properties and paleomagnetism of basalts from ODP Leg 107 basalts

The basalts recovered at Holes 651A and 655B appear to carry a single component remanent magnetization, which is generally of reversed polarity. These magnetizations are consistent with eruption during the Matuyama (651A) and Gilbert (655B) polarity epochs. The blocking temperature spectra and the Js/T curves indicate that titanomaghemite is the principal remanence carrier. The lower mean destructive field (MDF) and higher susceptibility at 651A probably indicates a lower mean oxidation state at this hole relative to 655B, which may simply reflect the age difference between the two basalt sequences. At both holes, a decreasing downcore trend both in natural remanent magnetization (NRM) and susceptibility probably indicates that maghemitization (from primary titanomagnetite) increases downcore. An interval of high coercivity at hole 655B (119.80-151.45 mbsf) appears to define a magnetically distinct unit within the basalt sequence.

Web-based Biodiversity Citizen Science Database (assembled 2012)

The collective impact of humans on biodiversity rivals mass extinction events defining Earth's history, but does our large population also present opportunities to document and contend with this crisis? We provide the first quantitative review of biodiversity-related citizen science to determine whether data collected by these projects can be, and are currently being, effectively used in biodiversity research. We find strong evidence of the potential of citizen science: within projects we sampled (n = 388), ~1.3 million volunteers participate, contributing up to US Dollar 2.5 billion in-kind annually. These projects exceed most federally-funded studies in spatial and temporal extent, and collectively they sample a breadth of taxonomic diversity. However, only 12% of the 388 projects surveyed obviously provide data to peer-reviewed scientific articles, despite the fact that a third of these projects have verifiable, standardized data that are accessible online. Factors influencing publication included project spatial scale and longevity and having publically available data, as well as one measure of scientific rigor (taxonomic identification training). Because of the low rate at which citizen science data reach publication, the large and growing citizen science movement is likely only realizing a small portion of its potential impact on the scientific research community. Strengthening connections between professional and non-professional participants in the scientific process will enable this large data resource to be better harnessed to understand and address global change impacts on biodiversity.

Paleomagnetic of lower Cretaceous sediments from the Argo and Gascoyne Abyssal Plain

Lower Cretaceous sediments were sampled for magnetostratigraphy at three sites. ODP Site 765 and DSDP Site 261, in the Argo Abyssal Plain, consist primarily of brownish-red to gray claystone having hematite and magnetite carriers of characteristic magnetization. ODP Site 766, in the Gascoyne Abyssal Plain, consists mainly of dark greenish-gray volcaniclastic turbidites with magnetite as the carrier of characteristic magnetization. Progressive thermal demagnetization (Sites 765 and 261) or alternating field demagnetization (Site 766) yielded well-defined polarity zones and a set of reliable paleolatitudes. Magnetic polarity chrons were assigned to polarity zones using biostratigraphic correlations. Late Aptian chron M"-1"r, a brief reversed-polarity chron younger than MOr, is a narrow, 40-cm feature delimited in Hole 765C. Early Aptian reversed-polarity chron MOr is also present in Hole 765C. Polarity chrons Mir through M3r were observed in the Barremian of all three sites. Valanginian and Hauterivian polarity chrons can be tentatively assigned to polarity zones only in Hole 766A. The paleolatitude of this region remained at 35° to 37°S from the Berriasian through the Aptian. During this interval, there was approximately 16° of clockwise rotation, with the oriented sample suites of Site 765 displaying a Berriasian declination of 307° to an Aptian declination of 323°. These results are consistent with the interpolated Early Cretaceous apparent polar wander for Australia, but indicate that this region was approximately 5? farther north than predicted.

Miocene magnetostratigraphy of ODP Site 199-1218 in the equatorial Pacific

Pliocene and Miocene magnetostratigraphy from ODP Site 1218 (Equatorial Pacific) has been obtained by measurements made on u-channel samples, augmented by about 50 discrete samples. U-channel samples were measured at 1 cm intervals and stepwise demagnetized in alternating fields up to a maximum peak field of 80 mT. The component magnetization directions were determined by principal component analysis for demagnetization steps in the 20-60 mT peak field range. A relatively small number of discrete samples were subject to both thermal and alternating field (AF) demagnetization and gave results compatible with u-channel measurements. Magnetostratigraphy from u-channel samples are compared with shipboard data that were based on blanket demagnetization at peak AF fields of 20 mT. U-channel measurements add more detail to the magnetostratigraphic record and allow identification of thin polarity zones especially in the upper part of the section were the sedimentation rates are very low (~2 m/Myr). The component magnetization directions determined from u-channel measurements also gave more reliable and precise estimates of inclination (paleolatitude). The magnetostratigraphy from Site 1218 can be unambiguously correlated with the reference geomagnetic polarity time scale and gives a means of dating the sedimentary sequence. Both Miocene-Pliocene and Oligocene-Miocene stage boundaries were easily identified from the magnetostratigraphic record. Although calculation of paleomagnetic poles is hindered by the low precision of the cores' azimuthal orientation, the data from both u-channel and discrete samples allow determination of the paleolatitude of the Site through time with good precision. Paleomagnetic data indicate that the paleolatitude of Site 1218 has increased form nearly equatorial latitude in the Oligocene to its present-day latitude close to 9°N. Within the precision of the paleomagnetic data, this is in agreement with current predictions of plate motion models based on fixed hotspots.

Characteristic magnetization of upper Cretaceous and lower Tertiary sediments

Lower Campanian to middle Eocene chalks and oozes were recovered at Sites 761 and 762 of Ocean Drilling Program Leg 122 on the Exmouth Plateau, northwest Australia. Paleomagnetic analyses were made on 125 samples from Hole 761B and 367 samples from Hole 762C. Thermal cleaning, alternating field demagnetization, or mixed treatment reveals a stable remanent component of normal or reversed polarity. Correlation of the magnetic polarity sequences established for these holes with the standard magnetic polarity time scale was aided by nannofossil zonation. At Hole 761B, the sequence extends from Subchron C32-N (upper Campanian) through Subchron C17-R (middle Eocene), but given the low sedimentation rate, not all the subchrons of the standard magnetic polarity sequence were recognized. The sequence at Hole 762C extends from Subchron C13-R (middle Eocene) to the boundary between Chrons C33 and C34 (lower Campanian). The sedimentation rate is higher at Hole 762C, and all the magnetic polarity subchrons of the Campanian and Maestrichtian stages were identified. Thus, this hole could be a reference section to refine the Upper Cretaceous time scale.

(Table 1) Minerals of bulk sediment at DSDP Holes 64-480 and 64-481

This paper provides a brief, descriptive, sedimentological background for the chapters on hydraulic piston core Site 480 in this symposium, and supplements data given in the site chapter for Sites 479-480 (this volume, Pt. 1). Sediments are composed primarily of planktonic diatoms, with minor numbers of silicoflagellates, radiolarians, and varying amounts of both benthic and planktonic foraminifers, along with a large terrigenous component of olive brown, silty clay. The section contains meter-thick intervals of finely laminated facies alternating with nonlaminated zones. A few paleoenvironmental events are documented within the generally uniform sequence by sporadic occurrences of thin turbidites, phosphatic concretions, fish debris concentrations, an ash layer, and a thin layer of diagenetic dolomite. The distribution of nonlaminated and laminated zones is attributed to fluctuations of bottom-water oxygen content caused by variations in circulation, fertility, and productivity. Homogeneous sections are interpreted as coinciding with cooler climatic periods, whereas laminated sections seem to correspond to upwelling conditions during drier periods.