All ICDP Publications with Abstracts
From parent-sysfolder "Publications" + 2 folder-levels deep
1919.
Erratum to: Bedrock geology of DFDP-2B, central Alpine Fault, New Zealand (New Zealand Journal of Geology and Geophysics, (2017), 60, 4, (497-518), 10.1080/00288306.2017.1375533)
New Zealand Journal of Geology and Geophysics,
60
(4)
vi
2017
ISSN: 00288306
Publisher: Taylor and Francis Asia Pacific
Abstract: ▾ When this paper was first published online the secondary affiliation for the author Virginia Gail Toy was omitted. The affiliation should have read: Hokkaido University - Earth and Planetary System Science, Department of Natural History Sciences, Graduate School of Sciences, Sapporo, Japan The supplemental data for this paper is also available at http://doi.org/10.5880/ICDP.5052.003. Taylor and Francis apologizes for these errors. © 2017 The Royal Society of New Zealand.
1918.
Evidence for a chondritic impactor, evaporation-condensation effects and melting of the Precambrian basement beneath the 'target' Deccan basalts at Lonar crater, India
Geochimica et Cosmochimica Acta,
21551-75
2017
Abstract: ▾ The ∼1.88 km diameter Lonar impact crater formed ∼570 ka ago and is an almost circular depression hosted entirely in the Poladpur suite of the ∼65 Ma old basalts of the Deccan Traps. To understand the effects of impact cratering on basaltic targets, commonly found on the surfaces of inner Solar System planetary bodies, major and trace element concentrations as well as Nd and Sr isotopic compositions were determined on a suite of selected samples composed of: basalts, a red bole sample, which is a product of basalt alteration, impact breccia, and impact glasses, either in the form of spherules (<1 mm in diameter) or non-spherical impact glasses (>1 mm and <1 cm). These data include the first highly siderophile element (HSE) concentrations for the Lonar spherules. The chemical index of alteration (CIA) values for the basalts and impact breccia (36.4–42.7) are low while the red bole sample shows a high CIA value (55.6 in the acid-leached sample), consistent with its origin by aqueous alteration of the basalts. The Lonar spherules are classified into two main groups based on their CIA values. Most spherules show low CIA values (Group 1: 34.7–40.5) overlapping with the basalts and impact breccia, while seven spherules show significantly higher CIA values (Group 2: >43.0). The Group 1 spherules are further subdivided into Groups 1a and 1b, with Group 1a spherules showing higher Ni and mostly higher Cr compared to the Group 1b spherules. Iridium and Cr concentrations of the spherules are consistent with the admixture of 1–8 wt% of a chondritic impactor to the basaltic target rocks. The impactor contribution is most prominent in the Group 1a and Group 2 spherules, which show higher Ni/Co, Ni/Cr and Cr/Co ratios compared to the target basalts. In contrast, the Group 1b spherules show major and trace element compositions that overlap with those of the impact breccia and are characterized by high EFTh (Enrichment Factor for Th defined as the Nb-normalized concentration of Th relative to that of the average basalt) as well as fractionated La/Sm(N), and higher large ion lithophile element (LILE) concentrations compared to the basalts. The relatively more radiogenic Sr and less radiogenic Nd isotopic composition of the impact breccia and non-spherical impact glasses compared to the target basalts are consistent with melting and mixing of the Precambrian basement beneath the Deccan basalt with up to 15 wt% contribution of the basement to these samples. Variations in the moderately siderophile element (MSE) concentration ratios of the impact breccia as well as all the spherules are best explained by contributions from three components – a chondritic impactor, the basaltic target rocks at Lonar and the basement underlying the Deccan basalts. The large variations in concentrations of volatile elements like Zn and Cu and correlated variations of EFCu-EFZn, EFPb-EFZn, EFK-EFZn and EFNa-EFZn, particularly in the Group 1a spherules, are best explained by evaporation-condensation effects during impact. While most spherules, irrespective of their general major and trace element composition, show a loss in volatile elements (e.g., Zn and Cu) relative to the target basalts, some spherules, mainly of Group 1, display enrichments in these elements that are interpreted to reflect the unique preservation of volatile-rich vapour condensates resulting from geochemical fractionation in a vertical direction within the vapour cloud. © 2017 Elsevier Ltd
1917.
Extreme hydrothermal conditions at an active plate-bounding fault
Nature,
546
(7656)
137-140
2017
ISSN: 00280836
Publisher: Nature Publishing Group
Keywords:▾
active fault; deformation; earthquake magnitude; earthquake rupture; fluid dynamics; heating; hydrostatic pressure; hydrothermal activity; hydrothermal system; movement; plate boundary; pressure effect; seismic zone; temperature effect; temperature gradient; topography, Article; earthquake; environmental temperature; heat; heating; hydrostatic pressure; pressure gradient; priority journal; rock; shear stress; topography
Abstract: ▾ Temperature and fluid pressure conditions control rock deformation and mineralization on geological faults, and hence the distribution of earthquakes. Typical intraplate continental crust has hydrostatic fluid pressure and a near-surface thermal gradient of 31 ± 15 degrees Celsius per kilometre. At temperatures above 300-450 degrees Celsius, usually found at depths greater than 10-15 kilometres, the intra-crystalline plasticity of quartz and feldspar relieves stress by aseismic creep and earthquakes are infrequent. Hydrothermal conditions control the stability of mineral phases and hence frictional-mechanical processes associated with earthquake rupture cycles, but there are few temperature and fluid pressure data from active plate-bounding faults. Here we report results from a borehole drilled into the upper part of the Alpine Fault, which is late in its cycle of stress accumulation and expected to rupture in a magnitude 8 earthquake in the coming decades. The borehole (depth 893 metres) revealed a pore fluid pressure gradient exceeding 9 ± 1 per cent above hydrostatic levels and an average geothermal gradient of 125 ± 55 degrees Celsius per kilometre within the hanging wall of the fault. These extreme hydrothermal conditions result from rapid fault movement, which transports rock and heat from depth, and topographically driven fluid movement that concentrates heat into valleys. Shear heating may occur within the fault but is not required to explain our observations. Our data and models show that highly anomalous fluid pressure and temperature gradients in the upper part of the seismogenic zone can be created by positive feedbacks between processes of fault slip, rock fracturing and alteration, and landscape development at plate-bounding faults. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
1916.
Erosion of Archean continents: The Sm-Nd and Lu-Hf isotopic record of Barberton sedimentary rocks
Geochimica et Cosmochimica Acta,
206216 – 235
2017
ISSN: 00167037
Publisher: Elsevier Ltd
Keywords:▾
South Africa; Ficus (angiosperm); Archean; chert; continental crust; erosion; hafnium; lutetium; mudstone; neodymium isotope; samarium; sandstone; sedimentary rock
Abstract: ▾ Knowing the composition, nature and amount of crust at the surface of the early Earth is crucial to understanding the early geodynamics of our planet. Yet our knowledge of the Hadean-Archean crust is far from complete, limited by the poor preservation of Archean terranes, and the fact that less attention has been paid to the sedimentary record that tracks erosion of these ancient remnants. To address this problem and get a more comprehensive view of what an Archean continent may have looked like, we investigated the trace element and Sm-Nd, Lu-Hf isotopic records of Archean metasedimentary rocks from South Africa. We focused our study on sandstone and mudstone from drill core in the Fig Tree Group (3.23–3.26 Ga) of the Barberton granite-greenstone belt, but also analyzed the 3.4 Ga Buck Reef cherts and still older (3.5–3.6 Ga) meta-igneous rocks from the Ancient Gneiss Complex, Swaziland. Based on principal component analysis of major and trace element data, the Fig Tree metasedimentary rocks can be classified into three groups: crustal detritus-rich sediments, Si-rich sediments and Ca-, Fe-rich sediments. The detritus-rich sediments have preserved the Sm-Nd and Lu-Hf isotopic signatures of their continental sources, and hence can be used to constrain the composition of crust eroded in the Barberton area in the Paleoarchean period. Based on Sm/Nd ratios, we estimate that this crust was more mafic than today, with an average SiO2 content of 60.5 ± 2 wt.%. This composition is further supported by isotopic mixing calculations suggesting that the sedimentary source area contained equal proportions of mafic-ultramafic and felsic rocks. This implies that the Archean crust exposed to weathering was more mafic than today but does not exclude a more felsic composition at depth. Neodymium and Hf crustal residence ages show that the eroded crust was, on average, ∼300–400 Ma older than the deposition age of the sediments, which highlights the importance of intracrustal reworking of older crust at ∼3.2 Ga in the Barberton area. The Si-rich sediments have slightly positive εNd (t=3.23Ga) but extremely radiogenic εHf (t=3.23Ga), up to +11. Based on analyses of 3.4 Ga Buck Reef cherts, we suggest that the radiogenic Hf isotopic signature of the Si-rich sediments can be accounted for by the old chert clasts or detrital silicified rock fragments present in the rocks. The latter have extremely high Lu/Hf ratios such that their εHf values would increase dramatically, by about +100 epsilon units every 100 Ma. In the Ca-, Fe-rich sediments, one sample contains carbonate that preserves the typical rare-earth element features of seawater precipitates. The initial Nd isotopic composition of this sample (εNd (t=3.23Ga) = +1.7) is within the range of previous estimates for Archean anoxic seawater. © 2017 Elsevier Ltd
1915.
Feldspar 40Ar/39Ar dating of ICDP PALEOVAN cores
Geochimica et Cosmochimica Acta,
217144-170
2017
ISSN: 00167037
Publisher: Elsevier Ltd
Keywords:▾
argon-argon dating; feldspar; grain size; lacustrine deposit; radiocarbon dating; sediment core; volcaniclastic deposit, Lake Van; Turkey
Abstract: ▾ Volcaniclastic fall deposits in ICDP drilling cores from Lake Van, Turkey, contain sodium-rich sanidine and calcium-rich anorthoclase, which both comprise a variety of textural zoning and inclusions. An age model records the lake's history and is based on climate-stratigraphic correlations, tephrostratigraphy, paleomagnetics, and earlier 40Ar/39Ar analyses (Stockhecke et al., 2014b). Results from total fusion and stepwise heating 40Ar/39Ar analyses presented in this study allow for the comparison of radiometric constraints from texturally diversified feldspar and the multi-proxy lacustrine age model and vice versa. This study has investigated several grain-size fractions of feldspar from 13 volcaniclastic units. The feldspars show textural features that are visible in cathodoluminescence (CL) or back-scattered electron (BSE) images and can be subdivided into three dominant zoning-types: (1) compositional zoning, (2) round pseudo-oscillatory zoning and (3) resorbed and patchy zoning (Ginibre et al., 2004). Round pseudo-oscillatory zoning records a sensitive alternation of Fe and Ca that also reflects resorption processes. This is only visible in CL images. Compositional zoning reflects anticorrelated anorthite and orthoclase contents and is visible in BSE. Eleven inverse isochron ages from total fusion and three from stepwise heating analyses fit the age model. Four experiments resulted in older inverse isochron ages that do not concur with the model within 2σ uncertainties and that deviate from 1 ka to 17 ka minimum. C- and R-type zoning are interpreted as representing growth in magma chamber cupolas, as wall mushes, or in narrow conduits. Persistent compositions of PO-type crystals and abundant surfaces recording dissolution features correspond to formation within a magma chamber. C-type zoning and R-type zoning have revealed an irregular incorporation of melt and fluid inclusions. These two types of zoning in feldspar are interpreted as preferentially contributing either heterogeneously distributed excess 40Ar or inherited 40Ar to the deviating 40Ar/39Ar ages that are discussed in this study. © 2017 Elsevier Ltd
1914.
Geochemical and microstructural evidence for interseismic changes in fault zone permeability and strength, Alpine Fault, New Zealand
Geochemistry, Geophysics, Geosystems,
18
(1)
238-265
2017
ISSN: 15252027
Publisher: Blackwell Publishing Ltd
Keywords:▾
Geochemistry; Lithology; Mechanical permeability; Microstructure; Mineralogy; Minerals; Sealing (finishing); Silicates, Alpine Faults; alteration; Fault rock; New zealand; seismic cycle, Rocks, chemical alteration; deformation; fault zone; geochemistry; lithology; microstructure; neotectonics; permeability; seismicity; slip rate; strain rate, Alpine Fault Zone; New Zealand; South Island
Abstract: ▾ Oblique dextral motion on the central Alpine Fault in the last circa 5 Ma has exhumed garnet-oligoclase facies mylonitic fault rocks from ∼35 km depth. During exhumation, deformation, accompanied by fluid infiltration, has generated complex lithological variations in fault-related rocks retrieved during Deep Fault Drilling Project (DFDP-1) drilling at Gaunt Creek, South Island, New Zealand. Lithological, geochemical, and mineralogical results reveal that the fault comprises a core of highly comminuted cataclasites and fault gouges bounded by a damage zone containing cataclasites, protocataclasites, and fractured mylonites. The fault core-alteration zone extends ∼20–30 m from the principal slip zone (PSZ) and is characterized by alteration of primary phases to phyllosilicate minerals. Alteration associated with distinct mineral phases occurred proximal the brittle-to-plastic transition (T ≤ 300–400°C, 6–10 km depth) and at shallow depths (T = 20–150°C, 0–3 km depth). Within the fault core-alteration zone, fractures have been sealed by precipitation of calcite and phyllosilicates. This sealing has decreased fault normal permeability and increased rock mass competency, potentially promoting interseismic strain buildup. © 2016. American Geophysical Union. All Rights Reserved.
1913.
Fifteen years of the Chinese continental scientific drilling program
Scientific Drilling,
221-18
2017
ISSN: 18168957
Publisher: Copernicus GmbH
Keywords:▾
Earthquakes; Metamorphic rocks, Chinese Government; Continental scientific drillings; Drilling projects; Earth's interior; Scientific drilling; South China block; Ultrahigh-pressure metamorphic; Wenchuan Earthquake, Drilling fluids
Abstract: ▾ Continental scientific drilling can be regarded as "a telescope into the Earth's interior" because it provides process insight and uncompromised samples of rocks, fluids, and even sampled from the deep biosphere from the Earth's surface to great depths. As one of the three founding members of the International Continental Scientific Drilling Program (ICDP), ICDP China has made great achievements in many scientific drilling-related research fields. Based on the ICDP participation it attracted global attention of scientists and set up not only the Chinese Continental Scientific Drilling (CCSD) Program in 2001 but also a growing number of ambitious drilling projects in the country. The 5158m deep borehole of the CCSD project at Donghai County in the Sulu ultrahigh-pressure metamorphic terrain demonstrates that large amounts of crustal rocks of the South China Block have been subducted to at least 120 km, followed by rapid uplift. After successful completion of drilling at Donghai, several continental scientific drilling projects were conducted with funding of the Chinese government and partially with support of ICDP, resulting in a total drilling depth of more than 35 000 m. These projects encompass the Continental Environmental Scientific Drilling Program of China, the Scientific Drilling Project of Wenchuan Earthquake Fault Zone, the Continental Scientific Drilling Project of Cretaceous Songliao Basin, and the Program of Selected Continental Scientific Drilling and Experiments. On the occasion of the 20th anniversary of the ICDP and the 15th anniversary of the CCSD Program, this paper reviews the history and major progress of the CCSD Program. © Author(s) 2017.
1912.
Fifteen years of the Chinese continental scientific drilling program
Scientific Drilling,
221-18
2017
ISSN: 18168957
Publisher: Copernicus GmbH
Keywords:▾
Earthquakes; Metamorphic rocks, Chinese Government; Continental scientific drillings; Drilling projects; Earth's interior; Scientific drilling; South China block; Ultrahigh-pressure metamorphic; Wenchuan Earthquake, Drilling fluids
Abstract: ▾ Continental scientific drilling can be regarded as "a telescope into the Earth's interior" because it provides process insight and uncompromised samples of rocks, fluids, and even sampled from the deep biosphere from the Earth's surface to great depths. As one of the three founding members of the International Continental Scientific Drilling Program (ICDP), ICDP China has made great achievements in many scientific drilling-related research fields. Based on the ICDP participation it attracted global attention of scientists and set up not only the Chinese Continental Scientific Drilling (CCSD) Program in 2001 but also a growing number of ambitious drilling projects in the country. The 5158m deep borehole of the CCSD project at Donghai County in the Sulu ultrahigh-pressure metamorphic terrain demonstrates that large amounts of crustal rocks of the South China Block have been subducted to at least 120 km, followed by rapid uplift. After successful completion of drilling at Donghai, several continental scientific drilling projects were conducted with funding of the Chinese government and partially with support of ICDP, resulting in a total drilling depth of more than 35 000 m. These projects encompass the Continental Environmental Scientific Drilling Program of China, the Scientific Drilling Project of Wenchuan Earthquake Fault Zone, the Continental Scientific Drilling Project of Cretaceous Songliao Basin, and the Program of Selected Continental Scientific Drilling and Experiments. On the occasion of the 20th anniversary of the ICDP and the 15th anniversary of the CCSD Program, this paper reviews the history and major progress of the CCSD Program. © Author(s) 2017.
1911.
Flowing fluid electrical conductivity logging of a deep borehole during and following drilling: estimation of transmissivity, water salinity and hydraulic head of conductive zones; [Diagraphie de la conductivité électrique des fluides d’un forage profond au cours et après la foration: estimation de la transmissivité, de la salinité de l’eau et de la charge hydraulique des zones conductrices]; [Condutividade elétrica em fluido registrada em poço profundo durante e após a perfuração: estimativa da transmissividade, salinidade da água e carga hidráulica de zonas condutivas]; [Registro de conductividad eléctrica en el flujo del fluido de un pozo profundo durante y después de la perforación: estimación de trasmisividad, salinidad del agua y carga hidráulica de las zonas conductivas]
Hydrogeology Journal,
25
(2)
501 – 517
2017
1910.
Fracturing, fluid-rock interaction and mineralisation during the seismic cycle along the Alpine Fault
Journal of Structural Geology,
103151-166
2017
ISSN: 01918141
Publisher: Elsevier Ltd
Keywords:▾
Calcite; Earthquakes; Energy dispersive spectroscopy; Fracture; Mica; Seismographs; Seismology; Shear strain; Thermodynamic stability; X ray diffraction, Alpine Faults; Alteration zones; Drilling projects; Fault structure; Fluid-rock interaction; Mineralisation; Seismogenic zones; Surrounding matrix, Mineralogy, cataclasite; fault zone; fracture; mineralization; seismic method; shear strain; slip, Alpine Fault Zone; New Zealand; South Island
Abstract: ▾ The Alpine Fault has a <50 m wide geochemically distinct hanging-wall alteration zone. Using a combination of petrological and cathodoluminescence (CL) microscopy, Energy Dispersive Spectroscopy and X-ray diffraction, we document the habitat and mineralising phases of macro- and micro-fractures within the alteration zone using samples derived from outcrop and the Deep Fault Drilling Project. Veins predominantly contain calcite, chlorite, K-feldspar or muscovite. Gouge-filled fractures are also observed and reflect filling from mechanical wear and chlorite mineralisation. CL imaging suggests that each calcite vein was opened and sealed in one episode, possibly corresponding to a single seismic cycle. The thermal stability of mineralising phases and their mutually cross-cutting relationships indicates a cyclic history of fracture opening and mineralisation that extends throughout the seismogenic zone. Cataclasites contain intragranular veins that are hosted within quartzofeldspathic clasts, as well as veins that cross-cut clasts and the surrounding matrix. Intragranular calcite veins formed prior to or during cataclasis. Cross-cutting veins are interpreted to have formed by fracturing of relatively indurated cataclasites after near-surface slip localisation within the Alpine Fault's principal slip zone gouges (PSZs). These observations clearly demonstrate that shear strain is most localised in the shallowest part of the seismogenic zone. © 2017 Elsevier Ltd
1909.
Fifteen years of the Chinese continental scientific drilling program
Scientific Drilling,
221 – 18
2017
ISSN: 18168957
Publisher: Copernicus GmbH
Keywords:▾
Earthquakes; Metamorphic rocks; Chinese Government; Continental scientific drillings; Drilling projects; Earth's interior; Scientific drilling; South China block; Ultrahigh-pressure metamorphic; Wenchuan Earthquake; Drilling fluids
Abstract: ▾ Continental scientific drilling can be regarded as "a telescope into the Earth's interior" because it provides process insight and uncompromised samples of rocks, fluids, and even sampled from the deep biosphere from the Earth's surface to great depths. As one of the three founding members of the International Continental Scientific Drilling Program (ICDP), ICDP China has made great achievements in many scientific drilling-related research fields. Based on the ICDP participation it attracted global attention of scientists and set up not only the Chinese Continental Scientific Drilling (CCSD) Program in 2001 but also a growing number of ambitious drilling projects in the country. The 5158m deep borehole of the CCSD project at Donghai County in the Sulu ultrahigh-pressure metamorphic terrain demonstrates that large amounts of crustal rocks of the South China Block have been subducted to at least 120 km, followed by rapid uplift. After successful completion of drilling at Donghai, several continental scientific drilling projects were conducted with funding of the Chinese government and partially with support of ICDP, resulting in a total drilling depth of more than 35 000 m. These projects encompass the Continental Environmental Scientific Drilling Program of China, the Scientific Drilling Project of Wenchuan Earthquake Fault Zone, the Continental Scientific Drilling Project of Cretaceous Songliao Basin, and the Program of Selected Continental Scientific Drilling and Experiments. On the occasion of the 20th anniversary of the ICDP and the 15th anniversary of the CCSD Program, this paper reviews the history and major progress of the CCSD Program. © Author(s) 2017.
1908.
Geochemical evidence of an extraterrestrial component in impact melt breccia from the Paleoproterozoic Dhala impact structure, India
Meteoritics and Planetary Science,
52
(4)
722-736
2017
Abstract: ▾ The Paleoproterozoic Dhala structure with an estimated diameter of ~11 km is a confirmed complex impact structure located in the central Indian state of Madhya Pradesh in predominantly granitic basement (2.65 Ga), in the northwestern part of the Archean Bundelkhand craton. The target lithology is granitic in composition but includes a variety of meta-supracrustal rock types. The impactites and target rocks are overlain by ~1.7 Ga sediments of the Dhala Group and the Vindhyan Supergroup. The area was cored in more than 70 locations and the subsurface lithology shows pseudotachylitic breccia, impact melt breccia, suevite, lithic breccias, and postimpact sediments. Despite extensive erosion, the Dhala structure is well preserved and displays nearly all the diagnostic microscopic shock metamorphic features. This study is aimed at identifying the presence of an impactor component in impact melt rock by analyzing the siderophile element concentrations and rhenium-osmium isotopic compositions of four samples of impactites (three melt breccias and one lithic breccia) and two samples of target rock (a biotite granite and a mafic intrusive rock). The impact melt breccias are of granitic composition. In some samples, the siderophile elements and HREE enrichment observed are comparable to the target rock abundances. The Cr versus Ir concentrations indicate the probable admixture of approximately 0.3 wt.% of an extraterrestrial component to the impact melt breccia. The Re and Os abundances and the 187Os/188Os ratio of 0.133 of one melt breccia specimen confirm the presence of an extraterrestrial component, although the impactor type characterization still remains inconclusive. © The Meteoritical Society, 2017.
1907.
{Environmental implications of salt facies in the Dead Sea}
GSA Bulletin,
128
(5-6)
824-841
052016
ISSN: 0016-7606DOI:10.1130/B31357.1
Abstract: ▾ {Thick sequences of salt (halite) have been recovered in a 456-m-long core drilled at the deepest floor of the Dead Sea by the Dead Sea Deep Drilling Project and extending ∼200 k.y. back in time. The salt sequences were precipitated in the ancient lake that occupied the Dead Sea Basin during the last three interglacials during intervals of extreme aridity in the lake’s watershed. The salt layers alternate with “mud” layers that indicate wetter periods in the watershed, when floods transported fine detritus matter to the lake. The salt sources include brine discharge and freshwater runoff that dissolved halite units. Dissolved salts accumulated in the lake during glacials and relatively wet periods when the lake expanded, and precipitated during interglacials when the lake levels dropped.This study establishes for the first time the evaporite facies and sedimentological features of the deep Dead Sea brine during interglacial periods, by using the modern precipitation of halite in the Dead Sea as an analogue for past halite depositional periods as recorded in the drill core. The halite intervals provide a record of facies characterizing a deep-water evaporitic environment. The halite layers consist mainly of two types of crystals: small cumulate crystals containing halite rafts, which indicate precipitation from the surface brine of the lake (epilimnion), and bottom-growth (usually large) halite crystals that precipitated on the lake floor (hypolimnion). The layers of small halite crystals formed during drier periods as compared to the bottom-growth crystals. The bottom-growth halite crystals contain variable quantities of detritus and show mild dissolution structures at the contact between the mud and the halite crystals. These two main types of halite, in combination with “muds” and gypsum, comprise seven categories of salt facies that reflect the hydrological conditions (dry-to-wet), and that display a cyclic (decadal to millennial) pattern along the sampled core intervals. Frequent alternation of these two salt crystal types suggests seasonal changes, whereby the small cumulate crystals were formed during the summer, and the bottom-growth crystals were formed during the winter, when the surface temperatures of the lake were low, and the surface water was less saline and less likely to be saturated with respect to halite. Comparison of the last interglacial halite with the modern halite facies, together with the absence of significant dissolution features within the halite and the cyclic nature of the facies, indicates that the lake was continuously deep (>100 m) during the last 200 k.y.}
1906.
Scientific drilling projects in ancient lakes: Integrating geological and biological histories
Global and Planetary Change,
143118-151
2016
ISSN: 09218181
Publisher: Elsevier B.V.
Keywords:▾
Biology; Geology; Paleolimnology, Analytical approach; Ancient lakes; Deep drilling; Evolutionary biology; Evolutionary information; Interdisciplinary project; Methodology; Sedimentary sequence, Lakes, biological survey; core analysis; data quality; deep drilling; evolutionary biology; fossil record; geological theory; integrated approach; lacustrine environment; outcrop; paleolimnology; technological change
Abstract: ▾ Sedimentary sequences in ancient or long-lived lakes can reach several thousands of meters in thickness and often provide an unrivalled perspective of the lake's regional climatic, environmental, and biological history. Over the last few years, deep-drilling projects in ancient lakes became increasingly multi- and interdisciplinary, as, among others, seismological, sedimentological, biogeochemical, climatic, environmental, paleontological, and evolutionary information can be obtained from sediment cores. However, these multi- and interdisciplinary projects pose several challenges. The scientists involved typically approach problems from different scientific perspectives and backgrounds, and setting up the program requires clear communication and the alignment of interests. One of the most challenging tasks, besides the actual drilling operation, is to link diverse datasets with varying resolution, data quality, and age uncertainties to answer interdisciplinary questions synthetically and coherently. These problems are especially relevant when secondary data, i.e., datasets obtained independently of the drilling operation, are incorporated in analyses. Nonetheless, the inclusion of secondary information, such as isotopic data from fossils found in outcrops or genetic data from extant species, may help to achieve synthetic answers. Recent technological and methodological advances in paleolimnology are likely to increase the possibilities of integrating secondary information. Some of the new approaches have started to revolutionize scientific drilling in ancient lakes, but at the same time, they also add a new layer of complexity to the generation and analysis of sediment-core data. The enhanced opportunities presented by new scientific approaches to study the paleolimnological history of these lakes, therefore, come at the expense of higher logistic, communication, and analytical efforts. Here we review types of data that can be obtained in ancient lake drilling projects and the analytical approaches that can be applied to empirically and statistically link diverse datasets to create an integrative perspective on geological and biological data. In doing so, we highlight strengths and potential weaknesses of new methods and analyses, and provide recommendations for future interdisciplinary deep-drilling projects. © 2016 Elsevier B.V.
1905.
Scientific drilling projects in ancient lakes: Integrating geological and biological histories
Global and Planetary Change,
143118 – 151
2016
ISSN: 09218181
Publisher: Elsevier B.V.
Keywords:▾
Biology; Geology; Paleolimnology; Analytical approach; Ancient lakes; Deep drilling; Evolutionary biology; Evolutionary information; Interdisciplinary project; Methodology; Sedimentary sequence; biological survey; core analysis; data quality; deep drilling; evolutionary biology; fossil record; geological theory; integrated approach; lacustrine environment; outcrop; paleolimnology; technological change; Lakes
Abstract: ▾ Sedimentary sequences in ancient or long-lived lakes can reach several thousands of meters in thickness and often provide an unrivalled perspective of the lake's regional climatic, environmental, and biological history. Over the last few years, deep-drilling projects in ancient lakes became increasingly multi- and interdisciplinary, as, among others, seismological, sedimentological, biogeochemical, climatic, environmental, paleontological, and evolutionary information can be obtained from sediment cores. However, these multi- and interdisciplinary projects pose several challenges. The scientists involved typically approach problems from different scientific perspectives and backgrounds, and setting up the program requires clear communication and the alignment of interests. One of the most challenging tasks, besides the actual drilling operation, is to link diverse datasets with varying resolution, data quality, and age uncertainties to answer interdisciplinary questions synthetically and coherently. These problems are especially relevant when secondary data, i.e., datasets obtained independently of the drilling operation, are incorporated in analyses. Nonetheless, the inclusion of secondary information, such as isotopic data from fossils found in outcrops or genetic data from extant species, may help to achieve synthetic answers. Recent technological and methodological advances in paleolimnology are likely to increase the possibilities of integrating secondary information. Some of the new approaches have started to revolutionize scientific drilling in ancient lakes, but at the same time, they also add a new layer of complexity to the generation and analysis of sediment-core data. The enhanced opportunities presented by new scientific approaches to study the paleolimnological history of these lakes, therefore, come at the expense of higher logistic, communication, and analytical efforts. Here we review types of data that can be obtained in ancient lake drilling projects and the analytical approaches that can be applied to empirically and statistically link diverse datasets to create an integrative perspective on geological and biological data. In doing so, we highlight strengths and potential weaknesses of new methods and analyses, and provide recommendations for future interdisciplinary deep-drilling projects. © 2016 Elsevier B.V.
1904.
Scientific drilling projects in ancient lakes: Integrating geological and biological histories
Global and Planetary Change,
143118 – 151
2016
ISSN: 09218181
Publisher: Elsevier B.V.
Keywords:▾
Biology; Geology; Paleolimnology; Analytical approach; Ancient lakes; Deep drilling; Evolutionary biology; Evolutionary information; Interdisciplinary project; Methodology; Sedimentary sequence; biological survey; core analysis; data quality; deep drilling; evolutionary biology; fossil record; geological theory; integrated approach; lacustrine environment; outcrop; paleolimnology; technological change; Lakes
Abstract: ▾ Sedimentary sequences in ancient or long-lived lakes can reach several thousands of meters in thickness and often provide an unrivalled perspective of the lake's regional climatic, environmental, and biological history. Over the last few years, deep-drilling projects in ancient lakes became increasingly multi- and interdisciplinary, as, among others, seismological, sedimentological, biogeochemical, climatic, environmental, paleontological, and evolutionary information can be obtained from sediment cores. However, these multi- and interdisciplinary projects pose several challenges. The scientists involved typically approach problems from different scientific perspectives and backgrounds, and setting up the program requires clear communication and the alignment of interests. One of the most challenging tasks, besides the actual drilling operation, is to link diverse datasets with varying resolution, data quality, and age uncertainties to answer interdisciplinary questions synthetically and coherently. These problems are especially relevant when secondary data, i.e., datasets obtained independently of the drilling operation, are incorporated in analyses. Nonetheless, the inclusion of secondary information, such as isotopic data from fossils found in outcrops or genetic data from extant species, may help to achieve synthetic answers. Recent technological and methodological advances in paleolimnology are likely to increase the possibilities of integrating secondary information. Some of the new approaches have started to revolutionize scientific drilling in ancient lakes, but at the same time, they also add a new layer of complexity to the generation and analysis of sediment-core data. The enhanced opportunities presented by new scientific approaches to study the paleolimnological history of these lakes, therefore, come at the expense of higher logistic, communication, and analytical efforts. Here we review types of data that can be obtained in ancient lake drilling projects and the analytical approaches that can be applied to empirically and statistically link diverse datasets to create an integrative perspective on geological and biological data. In doing so, we highlight strengths and potential weaknesses of new methods and analyses, and provide recommendations for future interdisciplinary deep-drilling projects. © 2016 Elsevier B.V.
1903.
Scientific drilling projects in ancient lakes: Integrating geological and biological histories
Global and Planetary Change,
143118 – 151
2016
ISSN: 09218181
Publisher: Elsevier B.V.
Keywords:▾
Biology; Geology; Paleolimnology; Analytical approach; Ancient lakes; Deep drilling; Evolutionary biology; Evolutionary information; Interdisciplinary project; Methodology; Sedimentary sequence; biological survey; core analysis; data quality; deep drilling; evolutionary biology; fossil record; geological theory; integrated approach; lacustrine environment; outcrop; paleolimnology; technological change; Lakes
Abstract: ▾ Sedimentary sequences in ancient or long-lived lakes can reach several thousands of meters in thickness and often provide an unrivalled perspective of the lake's regional climatic, environmental, and biological history. Over the last few years, deep-drilling projects in ancient lakes became increasingly multi- and interdisciplinary, as, among others, seismological, sedimentological, biogeochemical, climatic, environmental, paleontological, and evolutionary information can be obtained from sediment cores. However, these multi- and interdisciplinary projects pose several challenges. The scientists involved typically approach problems from different scientific perspectives and backgrounds, and setting up the program requires clear communication and the alignment of interests. One of the most challenging tasks, besides the actual drilling operation, is to link diverse datasets with varying resolution, data quality, and age uncertainties to answer interdisciplinary questions synthetically and coherently. These problems are especially relevant when secondary data, i.e., datasets obtained independently of the drilling operation, are incorporated in analyses. Nonetheless, the inclusion of secondary information, such as isotopic data from fossils found in outcrops or genetic data from extant species, may help to achieve synthetic answers. Recent technological and methodological advances in paleolimnology are likely to increase the possibilities of integrating secondary information. Some of the new approaches have started to revolutionize scientific drilling in ancient lakes, but at the same time, they also add a new layer of complexity to the generation and analysis of sediment-core data. The enhanced opportunities presented by new scientific approaches to study the paleolimnological history of these lakes, therefore, come at the expense of higher logistic, communication, and analytical efforts. Here we review types of data that can be obtained in ancient lake drilling projects and the analytical approaches that can be applied to empirically and statistically link diverse datasets to create an integrative perspective on geological and biological data. In doing so, we highlight strengths and potential weaknesses of new methods and analyses, and provide recommendations for future interdisciplinary deep-drilling projects. © 2016 Elsevier B.V.
1902.
Scientific drilling projects in ancient lakes: Integrating geological and biological histories
Global and Planetary Change,
143118-151
2016
ISSN: 09218181
Publisher: Elsevier B.V.
Keywords:▾
Biology; Geology; Paleolimnology, Analytical approach; Ancient lakes; Deep drilling; Evolutionary biology; Evolutionary information; Interdisciplinary project; Methodology; Sedimentary sequence, Lakes, biological survey; core analysis; data quality; deep drilling; evolutionary biology; fossil record; geological theory; integrated approach; lacustrine environment; outcrop; paleolimnology; technological change
Abstract: ▾ Sedimentary sequences in ancient or long-lived lakes can reach several thousands of meters in thickness and often provide an unrivalled perspective of the lake's regional climatic, environmental, and biological history. Over the last few years, deep-drilling projects in ancient lakes became increasingly multi- and interdisciplinary, as, among others, seismological, sedimentological, biogeochemical, climatic, environmental, paleontological, and evolutionary information can be obtained from sediment cores. However, these multi- and interdisciplinary projects pose several challenges. The scientists involved typically approach problems from different scientific perspectives and backgrounds, and setting up the program requires clear communication and the alignment of interests. One of the most challenging tasks, besides the actual drilling operation, is to link diverse datasets with varying resolution, data quality, and age uncertainties to answer interdisciplinary questions synthetically and coherently. These problems are especially relevant when secondary data, i.e., datasets obtained independently of the drilling operation, are incorporated in analyses. Nonetheless, the inclusion of secondary information, such as isotopic data from fossils found in outcrops or genetic data from extant species, may help to achieve synthetic answers. Recent technological and methodological advances in paleolimnology are likely to increase the possibilities of integrating secondary information. Some of the new approaches have started to revolutionize scientific drilling in ancient lakes, but at the same time, they also add a new layer of complexity to the generation and analysis of sediment-core data. The enhanced opportunities presented by new scientific approaches to study the paleolimnological history of these lakes, therefore, come at the expense of higher logistic, communication, and analytical efforts. Here we review types of data that can be obtained in ancient lake drilling projects and the analytical approaches that can be applied to empirically and statistically link diverse datasets to create an integrative perspective on geological and biological data. In doing so, we highlight strengths and potential weaknesses of new methods and analyses, and provide recommendations for future interdisciplinary deep-drilling projects. © 2016 Elsevier B.V.
1901.
Sedimentary PGE signatures in the Late Triassic ejecta deposits from Japan: Implications for the identification of impactor
Palaeogeography, Palaeoclimatology, Palaeoecology,
44236-47
2016
Abstract: ▾ Positive platinum group element (PGE) concentration and negative Os isotope anomalies reported from a claystone layer in the Upper Triassic bedded chert succession of the Sakahogi section, Mino Belt, central Japan, are thought to have been derived from an impact event. Stratigraphic variations and concentrations of PGE were examined in the Sakahogi section to determine the type of the impactor. Upper Triassic claystone layers, where PGE anomalies have been newly discovered in bedded chert successions in southwest Japan, were also examined. These include (i) the Unuma section in the Inuyama area, Mino Belt; (ii) the Hisuikyo section in the Kamiaso area, Mino Belt; and (iii) the Enoura section in the Tsukumi area, Chichibu Belt. Radiolarian and conodont biostratigraphic data indicate that these claystone layers are of upper-middle Norian age. Reconstruction of bedded chert in these sections suggests that they originate from open-ocean pelagic deep-sea sediments deposited in the Panthalassa Ocean.The relatively flat CI chondrite-normalized patterns of the least mobile PGEs (Ir, Ru, and Rh) and the Ru/Ir ratio determined by linear regression analysis suggest that a chondritic impactor is the source of the PGE anomalies preserved in claystone samples from the study sections. Although Ru/Ir ratios cannot conclusively distinguish chondrites from iron meteorites, the Cr/Ir ratios of the claystone layers range from 104 to 105, clearly indicating contribution from chondritic materials. The chondritic impactor of the suggested size (3.3-7.8km in diameter) implies that a large amount of debris and/or climatically active gasses (e.g., sulfur oxides) would have been released from the impactor, which would have had a marked effect on the environment. © 2015 Elsevier B.V.
1900.
Scientific drilling projects in ancient lakes: Integrating geological and biological histories
Global and Planetary Change,
143118-151
2016
ISSN: 09218181
Publisher: Elsevier B.V.
Keywords:▾
Biology; Geology; Paleolimnology, Analytical approach; Ancient lakes; Deep drilling; Evolutionary biology; Evolutionary information; Interdisciplinary project; Methodology; Sedimentary sequence, Lakes, biological survey; core analysis; data quality; deep drilling; evolutionary biology; fossil record; geological theory; integrated approach; lacustrine environment; outcrop; paleolimnology; technological change
Abstract: ▾ Sedimentary sequences in ancient or long-lived lakes can reach several thousands of meters in thickness and often provide an unrivalled perspective of the lake's regional climatic, environmental, and biological history. Over the last few years, deep-drilling projects in ancient lakes became increasingly multi- and interdisciplinary, as, among others, seismological, sedimentological, biogeochemical, climatic, environmental, paleontological, and evolutionary information can be obtained from sediment cores. However, these multi- and interdisciplinary projects pose several challenges. The scientists involved typically approach problems from different scientific perspectives and backgrounds, and setting up the program requires clear communication and the alignment of interests. One of the most challenging tasks, besides the actual drilling operation, is to link diverse datasets with varying resolution, data quality, and age uncertainties to answer interdisciplinary questions synthetically and coherently. These problems are especially relevant when secondary data, i.e., datasets obtained independently of the drilling operation, are incorporated in analyses. Nonetheless, the inclusion of secondary information, such as isotopic data from fossils found in outcrops or genetic data from extant species, may help to achieve synthetic answers. Recent technological and methodological advances in paleolimnology are likely to increase the possibilities of integrating secondary information. Some of the new approaches have started to revolutionize scientific drilling in ancient lakes, but at the same time, they also add a new layer of complexity to the generation and analysis of sediment-core data. The enhanced opportunities presented by new scientific approaches to study the paleolimnological history of these lakes, therefore, come at the expense of higher logistic, communication, and analytical efforts. Here we review types of data that can be obtained in ancient lake drilling projects and the analytical approaches that can be applied to empirically and statistically link diverse datasets to create an integrative perspective on geological and biological data. In doing so, we highlight strengths and potential weaknesses of new methods and analyses, and provide recommendations for future interdisciplinary deep-drilling projects. © 2016 Elsevier B.V.
1899.
Scientific drilling projects in ancient lakes: Integrating geological and biological histories
Global and Planetary Change,
143118-151
2016
ISSN: 0921-8181Keywords:▾
Ancient lake, Long-lived lake, Deep drilling, Evolutionary biology, Methodology, Paleolimnology
Abstract: ▾ Sedimentary sequences in ancient or long-lived lakes can reach several thousands of meters in thickness and often provide an unrivalled perspective of the lake's regional climatic, environmental, and biological history. Over the last few years, deep-drilling projects in ancient lakes became increasingly multi- and interdisciplinary, as, among others, seismological, sedimentological, biogeochemical, climatic, environmental, paleontological, and evolutionary information can be obtained from sediment cores. However, these multi- and interdisciplinary projects pose several challenges. The scientists involved typically approach problems from different scientific perspectives and backgrounds, and setting up the program requires clear communication and the alignment of interests. One of the most challenging tasks, besides the actual drilling operation, is to link diverse datasets with varying resolution, data quality, and age uncertainties to answer interdisciplinary questions synthetically and coherently. These problems are especially relevant when secondary data, i.e., datasets obtained independently of the drilling operation, are incorporated in analyses. Nonetheless, the inclusion of secondary information, such as isotopic data from fossils found in outcrops or genetic data from extant species, may help to achieve synthetic answers. Recent technological and methodological advances in paleolimnology are likely to increase the possibilities of integrating secondary information. Some of the new approaches have started to revolutionize scientific drilling in ancient lakes, but at the same time, they also add a new layer of complexity to the generation and analysis of sediment-core data. The enhanced opportunities presented by new scientific approaches to study the paleolimnological history of these lakes, therefore, come at the expense of higher logistic, communication, and analytical efforts. Here we review types of data that can be obtained in ancient lake drilling projects and the analytical approaches that can be applied to empirically and statistically link diverse datasets to create an integrative perspective on geological and biological data. In doing so, we highlight strengths and potential weaknesses of new methods and analyses, and provide recommendations for future interdisciplinary deep-drilling projects.
1898.
Seawater incursion event in Songliao Basin: New evidence from calcareous nannofossils of SK-1
Geological Bulletin of China,
35
(6)
866 – 871
2016
ISSN: 16712552
Publisher: China Geological Survey
Abstract: ▾ The Songliao Basin is the largest non-marine oil-bearing basin in China. Due to the absence of sufficient evidence, the hypothesis of seawater incursion(s) into the Songliao Basin remains controversial. Marine fossil materials can provide direct explanations. More recently, a few calcareous nannofossils were discovered from units 1 and 2 of the Nenjiang Formation in drill hole SK-1. In these fossils, some taxa have been positively identified, namely Calculites obscurus, Calculites ovalis, Quadrum sp., and Micula sp. They were distributed in marine environment of the Cretaceous. Based on comparisons of the calcareous nannofossil assemblages from global records, the age of units 1 of the Nenjiang Formation seems to have spanned from the latest Turonian to Maastrichtian. The nannofossils from the Songliao Basin have the marine origin, characterized by common diversity and abundance. The distribution and paleoecology of the calcareous nannofossils as well as the co-existing foraminifera in the SK-1 provide further evidence for seawater incursion events in the Songliao Basin. The authors hold that periodical seawater incursion(s) brought calcareous nannofossils and foraminifera into the Songliao Basin during sedimentation of units 1 and 2 of the Nenjiang Formation, when both lake and sea were at high level. © 2016, Science Press. All right reserved.
1897.
Sedimentological processes and environmental variability at Lake Ohrid (Macedonia, Albania) between 637 ka and the present
Biogeosciences,
13
(4)
1179 – 1196
2016
ISSN: 17264170
Publisher: Copernicus GmbH
Keywords:▾
Albania; Greece; Lake Ohrid; Macedonia [Greece]; Bacillariophyta; calcite; deep drilling; diatom; endemic species; epilimnion; geochemistry; lacustrine environment; lithotype; marine isotope stage; pelagic deposit; precipitation (chemistry); primary production; seasonal variation; silty clay; tephra
Abstract: ▾ Lake Ohrid (Macedonia, Albania) is thought to be more than 1.2 million years old and host more than 300 endemic species. As a target of the International Continental scientific Drilling Program (ICDP), a successful deep drilling campaign was carried out within the scope of the Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO) project in 2013. Here, we present lithological, sedimentological, and (bio-)geochemical data from the upper 247.8 m composite depth of the overall 569 m long DEEP site sediment succession from the central part of the lake. According to an age model, which is based on 11 tephra layers (first-order tie points) and on tuning of bio-geochemical proxy data to orbital parameters (second-order tie points), the analyzed sediment sequence covers the last 637 kyr. The DEEP site sediment succession consists of hemipelagic sediments, which are interspersed by several tephra layers and infrequent, thin (< 5 cm) mass wasting deposits. The hemipelagic sediments can be classified into three different lithotypes. Lithotype 1 and 2 deposits comprise calcareous and slightly calcareous silty clay and are predominantly attributed to interglacial periods with high primary productivity in the lake during summer and reduced mixing during winter. The data suggest that high ion and nutrient concentrations in the lake water promoted calcite precipitation and diatom growth in the epilimnion during MIS15, 13, and 5. Following a strong primary productivity, highest interglacial temperatures can be reported for marine isotope stages (MIS) 11 and 5, whereas MIS15, 13, 9, and 7 were comparably cooler. Lithotype 3 deposits consist of clastic, silty clayey material and predominantly represent glacial periods with low primary productivity during summer and longer and intensified mixing during winter. The data imply that the most severe glacial conditions at Lake Ohrid persisted during MIS16, 12, 10, and 6, whereas somewhat warmer temperatures can be inferred for MIS14, 8, 4, and 2. Interglacial-like conditions occurred during parts of MIS14 and 8. © Author(s) 2016.
1896.
Seismic anisotropy in mid to lower orogenic crust: Insights from laboratory measurements of Vp and Vs in drill core from central Scandinavian Caledonides
Tectonophysics,
69214--28
2016
ISSN: 0040-1951Keywords:▾
Shear zone, Seismic anisotropy seismic velocity, Caledonian orogen, Middle crust reflectivity, Deep scientific drilling
Abstract: ▾ Recent drilling of the first Collisional Orogeny in the Scandinavian Caledonides scientific borehole (COSC-1) near Åre, Sweden permitted a laboratory investigation of seismic anisotropy on high metamorphic grade and highly deformed core samples. The 2.5km deep borehole crosscuts the amphibolite-grade Lower Seve Nappe and intersects a high-strain shear zone in the lowermost 800m. Measurements of ultrasonic compressional (Vp) and shear (Vs) velocities are conducted at room temperature and pressures ranging from room conditions up to 260MPa on six core sections that represent the most abundant lithologies in the borehole. The core sections consist of two amphibolites, a calc-silicate gneiss, a felsic gneiss, an amphibole-rich gneiss, and a garnet-bearing micaschist from the shear zone. Three mutually perpendicular samples were taken to characterize the anisotropy induced by the clear foliation and lineation. The intrinsic (crack-free velocities) Vp0 and Vs0 in the direction perpendicular to foliation ranges from 5.51 to 6.67km/s and 3.31 to 4.13km/s, respectively. In the direction parallel to foliation the Vp0 and Vs0 ranges from 6.31 to 7.25km/s and 3.53 to 4.35km/s, respectively. Vp anisotropy ranges from 3% in the calc-silicate gneiss to 19% in the micaschist. In the upper crustal seismic reflection survey around the COSC-1 borehole, reflection coefficient analysis suggests that reflectors occur due to impedance contrast between commonly occurring amphibolites and gneisses in the upper 1800m and the micaschists below. When extrapolated to mid-crustal levels the analysis indicates that both rock types can produce reflection coefficients between adjacent lithologies in excess of 0.1. Similarities in lithologies, shear zone thickness, and reflectivity pattern in the Central Scandinavian Caledonides compared to other orogens (e.g., the Himalaya) demonstrate the importance of these measurements as a proxy for in-situ strongly anisotropic shear zones in the middle crust.
1895.
Seismic imaging in the eastern Scandinavian Caledonides: siting the 2.5 km deep COSC-2 borehole, central Sweden
Solid Earth,
7
(3)
769--787
2016
ISSN: 1869-9529