All ICDP Publications with Abstracts
From parent-sysfolder "Publications" + 2 folder-levels deep
2659.
Application of elemental capture spectroscopy in deep tight reservoir evaluation: A case study of well SK-2; [元素俘获能谱在深层致密储层评价中的应用: 以松科2井为例]
Earth Science Frontiers,
29
(1)
449 – 458
2022
ISSN: 10052321
Publisher: Science Frontiers editorial department
Keywords:▾
Brittleness; Fracture mechanics; Gases; Lithology; Organic carbon; Petroleum reservoir evaluation; Petroleum reservoirs; Plasticity; Porosity; Well logging; Brittleness index; Case-studies; Conventional well logs; Elemental capture spectroscopy; Gas logging; Gas potential; Shahezi formations; Songliao basin; Strong heterogeneities; Tight reservoir; Tight gas
Abstract: ▾ There are multiple gas logging anomalies in the Shahezi Formation, Songliao Basin, indicating its tight gas potential. However, deep tight reservoirs in the area have strong heterogeneity, thin thickness, interlayer development and various types. Based on the analysis of conventional well log of well SK-2, we used elemental capture spectroscopy (ECS) well logging to finely retrieve the mineral component content for accurate lithology identification, and subsequently identified five types of reservoirs by crossplot analysis. Combined with petrophysical experimental data, we further obtained the reservoir evaluation parameters such as variable skeleton porosity, brittleness index, and organic carbon content, which allowed us to categorize the reservoirs into three groups based on the well logging data and comprehensive evaluation indexes. In the Shahezi Formation (3730-4500 m), the porosity values range between 5%-9%, and the brittleness indexes range between 45%-60%. TOC of adjacent source rock is generally high, with relatively large accumulative thickness, and depth intervals at 3798-3831, 3950-3990 and 4150-4200 m show favorable tight gas potential for exploration and development. We demonstrated in this paper that, ECS well logging can accurately evaluate tight gas reservoirs so as to provide a reference basis for fracturing optimization in tight reservoirs. © 2022, Editorial Office of Earth Science Frontiers. All right reserved.
2658.
COSC-2 - drilling the basal décollement and underlying margin of palaeocontinent Baltica in the Paleozoic Caledonide Orogen of Scandinavia
Scientific Drilling,
3043--57
2022
ISSN: 1816-8957Abstract: ▾ {\textless}p{\textgreater}{\textless}strong class="journal-contentHeaderColor"{\textgreater}Abstract.{\textless}/strong{\textgreater} The Collisional Orogeny in the Scandinavian Caledonides (COSC) scientific drilling project aims to characterise the structure and orogenic processes involved in a major collisional mountain belt by multidisciplinary geoscientific research. Located in western central Sweden, the project has drilled two fully cored deep boreholes into the bedrock of the deeply eroded Early Paleozoic Caledonide Orogen. COSC-1 (2014) drilled a subduction-related allochthon and the associated thrust zone. COSC-2 (2020, this paper) extends this section deeper through the underlying nappes (Lower Allochthon), the main Caledonian décollement, and the upper kilometre of basement rocks. COSC-2 targets include the characterisation of orogen-scale detachments, the impact of orogenesis on the basement below the detachment, and the Early Paleozoic palaeoenvironment on the outer margin of palaeocontinent Baltica. This is complemented by research on heat flow, groundwater flow, and the characterisation of the microbial community in the present hard rock environment of the relict mountain belt. COSC-2 successfully, and within budget, recovered a continuous drill core to 2276 m depth. The retrieved geological section is partially different from the expected geological section with respect to the depth to the main décollement and the expected rock types. Although the intensity of synsedime{\textless}span id="page44"/{\textgreater}ntary deformation in the rocks in the upper part of the drill core might impede the analysis of the Early Paleozoic palaeoenvironment, the superb quality of the drill core and the borehole will facilitate research on the remaining targets and beyond. Protocols for sampling in the hard rock environment and subsequent sample preservation were established for geomicrobiological research and rock mechanical testing. For the former, a sparse sample series along the entire drill core was taken, while the target of the latter was the décollement. COSC-2 was surveyed by a comprehensive post-drilling downhole logging campaign and a combined borehole/land seismic survey in autumn 2021. This paper provides an overview of the COSC-2 (International Continental Scientific Drilling Project – ICDP 5054\_2\_A and 5054\_2\_B boreholes) operations and preliminary results. It will be complemented by a detailed operational report and data publication.{\textless}/p{\textgreater}
2657.
A low-temperature, meteoric water-dominated origin for smectitic clay minerals in the Chicxulub impact crater upper peak ring, as inferred from their oxygen and hydrogen isotope compositions
Chemical Geology,
588
2022
Abstract: ▾ The peak-ring of the 66 Ma, ~180 km Chicxulub impact structure in the northern Yucatán peninsula and southern Gulf of Mexico was sampled during the International Ocean Discovery Program and International Continental Scientific Drilling Program (IODP–ICDP) Expedition 364 at Site M0077 (21.45° N, 89.95° W). Secondary clay minerals are pervasive throughout the upper peak-ring lithologies as a product of ubiquitous altered glass present throughout the impact melt and melt-bearing breccia sequence. Here we present the first detailed study of the clay mineralogy (microprobe, pXRD, spectral reflectance from 350 to 2500 nm) and isotope geochemistry (δ2H and δ18O) of the <0.2 μm size-fraction from upper peak-ring lithologies. The clay mineralogy is dominated by smectitic clay minerals, whose composition varies with stratigraphic position. Trioctahedral Mg[sbnd]Fe smectite (var. saponite) is most common in Units or Subunits 2A, 2C, 3 and 4, while a section of Subunit 2B contains a more dioctahedral, Al-rich smectite. Higher porosity regions of the lower to mid, dioctahedral smectite-dominated intervals have higher δ18O (+14.2 to +18.6‰) whereas intervals dominated by trioctahedral smectite have lower δ18O (+10.4 to +14.1‰). The range of smectite δ2H (−105 to −87‰), in comparison to that of oxygen isotopes, is proportionally much less variable and unrelated to smectite mineralogy. When combined, the oxygen and hydrogen isotope compositions of the smectitic clay minerals suggest low temperature (~20 to 50 °C) formation from meteoric water-dominated fluids. The lower end of this temperature range is below current ambient conditions, which conceivably could suggest smectite formation before much of the overlying sedimentary rocks were deposited (~56 Ma?). Calculated temperatures are generally lower than those associated with impact-generated hydrothermal alteration. Calculated δ18O and δ2H of meteoric water-dominated fluids associated with low-temperature formation of these clay minerals are lower than known for modern meteoric water in the Yucatán region. The simplest explanation for the source of these ancient fluids is meteoric water-dominated Gulf Coast brines. A more remote possibility is orogenically-driven, long-distance transport of groundwater from highlands to the east via an artesian aquifer formed in part by fractured Mesozoic rocks extending laterally beneath the impact structure. © 2021 Elsevier B.V.
2656.
ICDP research drilling in the Moodies Group of the Barberton Greenstone Belt is underway
Geobulletin,
6518-21
2022
2655.
700,000 years of tropical Andean glaciation
Nature,
607
(7918)
301 – 306
2022
ISSN: 00280836
Publisher: Nature Research
Keywords:▾
Greenland; Ice Cover; Temperature; Amazon River; Arctic; Greenland; glaciation; monsoon; Pleistocene; teleconnection; article; glaciation; Greenland; information center; periodicity; precipitation; ice cover; temperature
Abstract: ▾ Our understanding of the climatic teleconnections that drove ice-age cycles has been limited by a paucity of well-dated tropical records of glaciation that span several glacial–interglacial intervals. Glacial deposits offer discrete snapshots of glacier extent but cannot provide the continuous records required for detailed interhemispheric comparisons. By contrast, lakes located within glaciated catchments can provide continuous archives of upstream glacial activity, but few such records extend beyond the last glacial cycle. Here a piston core from Lake Junín in the uppermost Amazon basin provides the first, to our knowledge, continuous, independently dated archive of tropical glaciation spanning 700,000 years. We find that tropical glaciers tracked changes in global ice volume and followed a clear approximately 100,000-year periodicity. An enhancement in the extent of tropical Andean glaciers relative to global ice volume occurred between 200,000 and 400,000 years ago, during sustained intervals of regionally elevated hydrologic balance that modified the regular approximately 23,000-year pacing of monsoon-driven precipitation. Millennial-scale variations in the extent of tropical Andean glaciers during the last glacial cycle were driven by variations in regional monsoon strength that were linked to temperature perturbations in Greenland ice cores1; these interhemispheric connections may have existed during previous glacial cycles. © 2022, The Author(s).
2654.
A Four-Phase Model for Methane Production from an Unconsolidated Hydrate Reservoir. Part 1. Model Development
Industrial and Engineering Chemistry Research,
61
(20)
7103-7113
2022
ISSN: 08885885
Publisher: American Chemical Society
Keywords:▾
Confined flow; Gas hydrates; Granular materials; Shear stress, Flow modelling; Four-phase; Gas sands; Gas-water; Granular flows; Methane production; Model development; Phase flow; Phase model; Solid phase models, Hydration
Abstract: ▾ A four-phase flow model is developed to capture the unconsolidated flow of gas, water, hydrate, and sand. The solid phase models are an extension of granular flow theory to unconsolidated hydrate-bearing sediment. A solid viscosity constitutive model is developed to model the frictional and cohesive contributions to the solid shear stress. In part 2 of this paper series, the model is validated against the Mallik 2007/2008 production tests. © 2022 American Chemical Society. All rights reserved.
2653.
A Four-Phase Model for Methane Production from an Unconsolidated Hydrate Reservoir. Part 2. Numerical Simulation
Industrial and Engineering Chemistry Research,
61
(20)
7114-7129
2022
ISSN: 08885885
Publisher: American Chemical Society
Keywords:▾
Gas hydrates; Hydration; Petroleum reservoir engineering, Flow modelling; Four-phase; Methane hydrates; Methane production; Model development; Phase flow; Phase model; Production test; Sand production; Solid deformation, Methane
Abstract: ▾ In this paper, the Mallik production tests are simulated using our four-phase flow model for an unconsolidated methane hydrate reservoir. Model development was outlined in part 1 of this paper series. The simulations suggest that the unconsolidated hydrate reservoir with sand production behaves like a naturally fracking reservoir. Solid deformation and the resultant permeability have a substantial effect on the gas production from an unconsolidated hydrate reservoir whether sand is produced or not. © 2022 American Chemical Society. All rights reserved.
2652.
A geochronologically-constrained stable isotope record of the Upper Triassic Sonsela Member (Chinle Formation) at Petrified Forest National Park (Arizona, USA): Testing for paleoenvironmental linkages with biotic change and the Manicouagan impact
Palaeogeography, Palaeoclimatology, Palaeoecology,
601
2022
ISSN: 00310182
Publisher: Elsevier B.V.
Keywords:▾
geochronology; historical record; paleoclimate; paleoenvironment; preservative; proxy climate record; stable isotope; Triassic, Arizona; United States
Abstract: ▾ The Upper Triassic Chinle Formation, cropping out in and around Petrified Forest National Park (PFNP) in northern Arizona, U.S.A., preserves an important non-marine biotic and sedimentologic record of Late Triassic key Earth-life events. In 2013, the Colorado Plateau Coring Project (CPCP) obtained a 520-m-long core of the Triassic strata at PFNP to study this sedimentary record in unequivocal superposition and, among other goals, to test hypotheses about the paleoenvironmental and biotic changes preserved in the Sonsela Member of the Chinle Formation, and specifically their link to the Manicouagan impact and the Adamanian-Revueltian biotic turnover event (A-R transition). We sampled the Sonsela Member of CPCP core 1A for bulk organic material and for pedogenic carbonates to establish the δ13Corg, δ13Ccarb, and δ18Ocarb records. Throughout much of the Sonsela Member, the stable isotope record is characterized by a relatively narrow range of values (δ13Corg = ~ −25 to −30‰; δ13Ccarb = ~ −7 to −10‰; and δ18Ocarb = ~ −5 to −8‰). Based on these data, we estimate mean annual precipitation and correlate our isotope record to two previously developed, high resolution, multi-proxy age models for the CPCP core. Our new data set supports three main conclusions based on these observations: (1) whereas the A-R transition and the Manicouagan impact event might correlate in time, establishing a causal relationship between those two events remains challenging; (2) the Manicouagan impact as well as the A-R transition are not linked to a clear geochemical perturbation preserved in the CPCP core; and (3) multiple proxies agree the climate became more arid throughout the Sonsela Member, possibly contributing to the Adamanian-Revueltian biotic turnover. © 2022 Elsevier B.V.
2651.
A Late Pleistocene (MIS4-MIS2) palaeohydrological reconstruction from Lake Chalco, Basin of Mexico
Journal of South American Earth Sciences,
119
2022
ISSN: 08959811
Publisher: Elsevier Ltd
Keywords:▾
environmental change; evapotranspiration; ostracod; paleohydrology; Pleistocene; salinity; warming; water level, Lake Chalco; Mexico [North America]
Abstract: ▾ We present a palaeohydrological reconstruction of Lake Chalco from 70 to 11.5 ka BP based on ostracod records consisting of three species: Limnocytherina axalapasco, Candona patzcuaro, and Cypridopsis vidua. Overall, the presence of these species helped investigate Lake Chalco water level fluctuations, and thus water salinity variations. Moreover, this work helped improve our knowledge of L. axalapasco and Candona alchichica, two endemic species of Central Mexico, the latter of which was replaced by C. patzcuaro after the cold and dry MIS4. Five ostracod zones reflect the main environmental changes that occurred during the Late Pleistocene. During 70–62 ka BP (Zone 5), shallow and very variable salinity conditions were inferred with a possible occupancy of submerged macrophytes. The Lake Chalco water level increased from 62 to 49 ka BP (Zone 4) and relatively less saline conditions were inferred. The warmer period from of 49–39 ka BP (Zone 3) was characterised by lower lake levels and a gradually increasing salinity. The evaporation rates continued to increase during 39–27 ka BP (Zone 2). However, a higher runoff input helped maintain a relatively high lake level. Later on, cold and dry conditions from 27 to 11.5 ka BP (Zone 1) inhibited the ostracod occupancy in Lake Chalco. © 2022 Elsevier Ltd
2650.
A Reference Section Through Fast-Spread Lower Oceanic Crust, Wadi Gideah, Samail Ophiolite (Sultanate of Oman): Whole Rock Geochemistry
Journal of Geophysical Research: Solid Earth,
127
(6)
2022
ISSN: 21699313
Publisher: John Wiley and Sons Inc
Keywords:▾
gabbro; geochemistry; oceanic crust; seafloor spreading; trace element; transect, Oman; Semail Ophiolite
Abstract: ▾ Due to its inaccessibility, no complete and coherent data set exists for the composition of modern fast-spreading oceanic crust. We sampled outcrops through 6,500 m of fossil oceanic crust in the Oman Ophiolite (Wadi Gideah Transect) that is regarded as best analogue of fast-spreading crust on land. Here we report a complete set of whole-rock major and trace element data displaying systematic and contrasting compositional trends in lower and upper gabbros being correlated with stratigraphic depth. A significant discontinuity in crystallization regime is observed at ∼3,525 m above the mantle-crust boundary: gabbros below ∼3,525 m have in general very low incompatible element mass fractions which develop upwards in a barely noticeable way to more differentiated compositions while Mg# decreases. More pronounced trends indicating progressive fractionation of ascending melts can be observed for incompatible elements and their element ratios as a consequence of in situ crystallization. Locally, more variable compositions within narrow depth intervals testify for advanced differentiation in situ within individual sills. Gabbros above ∼3,525 m become significantly more evolved and show considerable variations in composition. Fractional crystallization and mixing processes in a transient axial melt lens control the composition of isotropic “varitextured” gabbros and sheeted dike basalts where fractionation of high field strength elemental ratios is minor. New average compositions of fast-spread (paleo) oceanic crust are reported for major and 38 trace elements. Comparison with new data from Wadi Khafifah close to Wadi Gideah suggests robustness of crustal accretion processes in both space and time. © 2022. The Authors.
2649.
Anisotropic velocity models for (3-D) seismic imaging of the Lower Seve Nappe in Jämtland, Sweden
Geophysical Journal International,
228
(1)
66 – 77
2022
ISSN: 0956-540XAbstract: ▾ Strong anisotropy of seismic velocity in the Earth's crust poses serious challenges for seismic imaging. Where in situ seismic properties are not available, the anisotropy can be determined from velocity analysis of surface and borehole seismic profiles. This is well established for dense, long-offset reflection seismic data. However, it is unknown how applicable this approach is for sparse seismic reflection data with low fold and short offsets in anisotropic metamorphic rocks. Here, we show that anisotropy parameters can be determined from a sparse 3-D data set at the COSC-1 borehole site in the Swedish Caledonides and that the results agree well with the seismic anisotropy parameters determined from seismic laboratory measurements on core samples. Applying these anisotropy parameters during 3-D seismic imaging improves the seismic image of the high-amplitude reflections especially in the vicinity of the lower part of the borehole. Strong reflections in the resulting seismic data show good correlation with the borehole-derived lithology. Our results aid the interpretation and extrapolation of the seismic stratigraphy of the Lower Seve Nappe in Jämtland and other parts in the Caledonides.
2648.
A stronger role for long-term moisture change than for CO2 in determining tropical woody vegetation change
Science,
376
(6593)
2022
2647.
A Study on the Sedimentation Rate of the Denglouku Formation from CCSD SK-2, Based on Logging Spectral Analysis [基于测井频谱分析的松科二井登娄库组地层沉积速率研究]
Acta Geoscientica Sinica,
43
(5)
654-664
2022
ISSN: 10063021
Publisher: Science Press
Abstract: ▾ The SK-2 of China Continental Scientific Drilling Project (CCSD) in the Songliao Basin recorded the Cretaceous continental sedimentary data. The continuous, multi-parameter, high-resolution geophysical logging data provided an opportunity to study the variation in sedimentation rate in the Songliao Basin. In this study, we used GR, Th, K, and Th/K logging data to calculate the sedimentation rate using the astronomical cycle method and discussed the main controlling factors affecting sediment formation. Spectral analysis results of various logging data showed that the Denglouku Formation has recorded the information of the great Milankovitch cycle information, and the sedimentation process is affected by the driving force of the astronomical orbit. Th data are highly sensitive to astronomical period information, and comprehensively considering the results of various logging data, a continuous and relatively accurate sedimentation rate has been obtained. The sedimentation rate showed a trend from high to low with depth from bottom to top. Sedimentation of the second to third members of the Denglouku Formation was mainly controlled by the faulting activities of the basin, and the overall sedimentation rate was high, reaching a maximum of 16.2 cm/ka. From then on to the fourth member of the Denglouku Formation, the basin transformed into a regional depression structure owing to the gradual weakening of the rifting activity, and the formation had a low sedimentation rate; the lowest rate was 5.9 cm/ka. This study established a continuous sedimentation rate profile of the Denglouku Formation from CCSD SK-2, which provided logging evidence for revealing the geological law of the transition from rifting activity to depression activity in the Songliao Basin. © 2022, Science Press. All right reserved.
2646.
A Trial Evaluation of Rock Core DCDA Absolute Differential Stress Measurement for Routine Quantitative Mining Hazard Assessment in Deep Underground High Stress Mines; [研精覃 ?， ?微知著-人工智能开 ? 精准病 ? 诊断新时代]
Zairyo/Journal of the Society of Materials Science, Japan,
71
(3)
259 – 264
2022
2645.
3D imaging of the subsurface electrical resistivity structure in West Bohemia/Upper Palatinate covering mofettes and Quaternary volcanic structures by using Magnetotellurics
Tectonophysics,
833
2022
ISSN: 00401951
Publisher: Elsevier B.V.
Keywords:▾
Bohemian Massif; Electric conductivity; Magnetotellurics; Strike-slip faults; Structural geology; Volcanoes; 2-d inversions; Conductive channels; Earthquake swarms; Fluid pathways; Fluid/magma reservoir; Inversion results; Magma reservoirs; Ohře rift; Study areas; Volcanic structures; earthquake swarm; electrical resistivity; magnetotelluric method; Quaternary; rift zone; three-dimensional modeling; volcanism; volcanology; Earthquakes
Abstract: ▾ The region of West Bohemia and Upper Palatinate belongs to the West Bohemian Massif. The study area is situated at the junction of three different Variscan tectonic units and hosts the ENE-WSW trending Ohře Rift as well as many different fault systems. The entire region is characterized by ongoing magmatic processes in the intra-continental lithospheric mantle expressed by a series of phenomena, including e.g. the occurrence of repeated earthquake swarms and massive degassing of mantle derived CO2 in form of mineral springs and mofettes. Ongoing active tectonics is mainly manifested by Cenozoic volcanism represented by different Quaternary volcanic structures. All these phenomena make the Ohře Rift a unique target area for European intra-continental geo-scientific research. With magnetotelluric (MT) measurements we image the subsurface distribution of the electrical resistivity and map possible fluid pathways. Two-dimensional (2D) inversion results by Muñoz et al. (2018) reveal a conductive channel in the vicinity of the earthquake swarm region that extends from the lower crust to the surface forming a pathway for fluids into the region of the mofettes. A second conductive channel is present in the south of their model; however, their 2D inversions allow ambiguous interpretations of this feature. Therefore, we conducted a large 3D MT field experiment extending the study area towards the south. The 3D inversion result matches well with the known geology imaging different fluid/magma reservoirs at crust-mantle depth and mapping possible fluid pathways from the reservoirs to the surface feeding known mofettes and spas. A comparison of 3D and 2D inversion results suggests that the 2D inversion results are considerably characterized by 3D and off-profile structures. In this context, the new results advocate for the swarm earthquakes being located in the resistive host rock surrounding the conductive channels; a finding in line with observations e.g. at the San Andreas Fault, California. © 2022 The Authors
2644.
Alteration of basaltic glass within the Surtsey hydrothermal system, Iceland – Implication to oceanic crust seawater interaction
Journal of Volcanology and Geothermal Research,
429
2022
ISSN: 03770273
Publisher: Elsevier B.V.
Keywords:▾
Alumina; Aluminum oxide; Basalt; Budget control; Calcium; Chemical analysis; Clay alteration; Glass; Iron oxides; Magnesia; Nanocomposites; Seawater; Silica; Silicon; Sodium compounds; Temperature; Titanium dioxide; Trace elements, Basaltic glass; Bulk rocks; Element mobility; Hydrothermal alterations; ICDP; Icelands; Mass balance; Palagonitization; Surtsey volcano; SUSTAIN, Volcanoes, basalt; glass; hydrothermal alteration; hydrothermal system; mass balance; oceanic crust; seawater; trace element, Iceland; Surtsey
Abstract: ▾ Low-temperature hydrothermal alteration of basaltic glass on the seafloor has important implications on the chemical evolution of the oceanic crust and seawater composition. However, mass fluxes resulting from seawater-glass interaction in this type of environment remain poorly understood. This study presents new results on element mobilities for the palagonitization of basaltic glass and bulk rock hydrothermal alteration at Surtsey volcano, Iceland over a time period of ~50-years. Assessments of element mobilities were based on 1) immobile trace element isocon mass balance for palagonitization, 2) the assumption of large scale TiO2 immobility during bulk rock alteration and 3) chemical analyses of pore fluids and authigenic minerals. Element mobilities of glass alteration vary between initial palagonitization and subsequent palagonite maturation: Initially, palagonitization of sideromelane leaches SiO2, Al2O3, MgO, CaO, Na2O, K2O from the glass. Following this, the maturation of the palagonitized glass causes re-uptake of all of the abovementioned elements except for CaO, which shows either no change or slight uptake, and Na2O, which continues to be lost from the palagonitized glass. Among major elements TiO2 and FeO can be considered immobile during palagonitization, but not during the subsequent aging process of palagonitized glass. Among trace elements Hf, Ta, Zr, Nb, Y and REE were found to be immobile at all stages of the alteration. On the bulk rock scale, comprising both glass alteration and the formation of authigenic phases, early-stage alteration at Surtsey releases SiO2, Al, Mg and Ca to the fluid, whereas late-stage alteration poses a sink of SiO2, Al, Mg, Ca and Na. Net element budgets during early- and late-stage alteration indicate that chemical exchange between basaltic tuffs and seawater derived fluids at Surtsey acts as a long-term source of dissolved Ca, Al and SiO2 for seawater as well as a long-term sink for seawater Mg and Na. © 2022 Elsevier B.V.
2643.
An astronomical age-depth model and reconstruction of moisture availability in the sediments of Lake Chalco, central Mexico, using borehole logging data
Quaternary Science Reviews,
294
2022
ISSN: 02773791
Publisher: Elsevier Ltd
Keywords:▾
Carbon dioxide; Climate models; Continuous time systems; Gamma rays; Glacial geology; Lakes; Magnetic susceptibility; Magnetism; Moisture determination; Sediments; Tropics, %moisture; Authigenic; Authigenic urania; Cyclostratigraphy; Depth models; Milankovitch cycle; Palaeoclimatology; Quaternary; Spectral gamma rays; Tropical north america, Moisture, astronomy; borehole logging; interglacial; lacustrine deposit; lake level; magnetic susceptibility; moisture content; paleoclimate; Pleistocene; Postglacial; precession; reconstruction; uranium, Federal District [Mexico]; Lake Chalco; Mexico City; Mexico [North America]
Abstract: ▾ Understanding the moisture history of low latitudes from the most recent glacial period of the latest Pleistocene to post-glacial warmth in continental tropical regions is hampered by the lack of continuous time series. We conducted downhole spectral gamma (γ) ray and magnetic susceptibility logs over 300 m of lacustrine deposits of Lake Chalco (Mexico City) to reconstruct an age-depth model using an astronomical and correlative approach, and to reconstruct long-term moisture availability. Our results suggest that the Lake Chalco sediments contain several rhythmic alternations with a quasi-cyclic pattern comparable to the Pleistocene benthic stack. This allows us to calculate a time span of about 500,000 years for this sediment deposition. We developed proxies for moisture, detrital input, and salinity, all based on the physical properties of γ-ray spectroscopy and magnetic susceptibility. Our results indicate that Lake Chalco formed during Marine Isotope Stage 13 (MIS13) and the lake level gradually increased over time until the interglacial MIS9. Moisture content is generally higher during interglacials than during glacials. However, two periods, namely MIS6 and MIS4, have higher moisture contents. We developed a model by comparing the obtained moisture proxy with climatic drivers, to understand how different climate systems drove effective moisture availability in the Chalco sub-basin over the past 500,000 years. Carbon dioxide, eccentricity, and precession are all key drivers of the moisture content of Lake Chalco over the past 500,000 years. © 2022 The Authors
2642.
An ostracod-based record of paleoecological conditions during MIS6 and MIS5, from Lake Chalco, Basin of Mexico
Journal of Paleolimnology,
67
(4)
359-373
2022
ISSN: 09212728
Publisher: Springer Science and Business Media B.V.
Keywords:▾
dissolved oxygen; environmental conditions; lake level; lake water; marine isotope stage; ostracod; paleoecology; runoff; seawater, Lake Chalco; Mexico [North America]; Valley of Mexico
Abstract: ▾ A sediment record from Lake Chalco, Basin of Mexico, revealed the presence of two endemic ostracod species during the latter part of Marine Isotope Stages (MIS) 6 (146–130 ka) and MIS5 (130–72 ka), namely Candona alchichica and Limnocytherina axalapasco. Higher abundance of C. alchichica was found during MIS6, when prevailing conditions were cold, lake waters were fresh, and relatively deep bottom waters were anoxic. The species is typically associated with saline environments today, consistent with its presence in MIS5 sediments. The Chalco record, however, reveals that it coexisted with freshwater diatom species during MIS6. Thus, we suggest that C. alchichica had a wider salinity tolerance, ranging from freshwater to more saline environments. Examination of MIS5 substages provides further insights into ostracod species responses to changing lake conditions. During MIS5e, the lake water level declined and salinity and dissolved oxygen in the water column increased, thereby favouring L. axalapasco productivity, whereas C. alchichica productivity decreased. Enhanced runoff and lower than average evaporation during MIS5d coincided with the increasing abundance of C. alchichica, suggesting a period of relatively high lake level and more dilute waters. These environmental conditions, however, changed during MIS5c when lake stage dropped once again and L. axalapasco abundance increased. Shallow conditions during this substage were optimal for L. axalapasco. Subsequently, as the lake level continued to decline during MIS5b, both ostracod species disappeared from the sediment record. Finally, during MIS5a, runoff increased and both ostracod species reappeared in the record, with L. axalapasco dominating, suggesting another period of lake level recovery. Increased evaporation rates during the last part of this substage (75–72 cal ka BP) may have led to disappearance of ostracods from the sediment record. Overall, during MIS5, we detected higher L. axalapasco, which represent relatively shallow lake conditions. © 2022, The Author(s), under exclusive licence to Springer Nature B.V.
2641.
Convective Melting and Water Behavior around Magmatic-Hydrothermal Transition: Numerical Modeling with Application to Krafla Volcano, Iceland
Journal of Petrology,
63
(8)
2022
2640.
86Kr excess and other noble gases identify a billion-year-old radiogenically-enriched groundwater system
Nature Communications,
13
(1)
2022
ISSN: 20411723
Publisher: Nature Research
Keywords:▾
ground water; helium; helium 4; inert gas; krypton 86; neon; radioisotope; unclassified drug; uranium; xenon; xenon 136; inert gas, basement rock; concentration (composition); groundwater resource; helium; microbial community; Precambrian, air pollution; Article; astronomy; chemical composition; concentration (parameter); controlled study; geological time; gold mining; hydrosphere; Precambrian; sediment; South Africa; surface property; water residence time; water supply; geology; microflora, South Africa, Earth, Planet; Geology; Groundwater; Microbiota; Noble Gases
Abstract: ▾ Deep within the Precambrian basement rocks of the Earth, groundwaters can sustain subsurface microbial communities, and are targets of investigation both for geologic storage of carbon and/or nuclear waste, and for new reservoirs of rapidly depleting resources of helium. Noble gas-derived residence times have revealed deep hydrological settings where groundwaters are preserved on millions to billion-year timescales. Here we report groundwaters enriched in the highest concentrations of radiogenic products yet discovered in fluids, with an associated 86Kr excess in the free fluid, and residence times >1 billion years. This brine, from a South African gold mine 3 km below surface, demonstrates that ancient groundwaters preserved in the deep continental crust on billion-year geologic timescales may be more widespread than previously understood. The findings have implications beyond Earth, where on rocky planets such as Mars, subsurface water may persist on long timescales despite surface conditions that no longer provide a habitable zone. © 2022, The Author(s).
2639.
Culturable Bacterial Diversity from the Basaltic Subsurface of the Young Volcanic Island of Surtsey, Iceland
Microorganisms,
10
(6)
1177
2022
2638.
High resolution environmental conditions of the last interglacial (MIS5e) in the Levant from Sr, C and O isotopes from a Jerusalem stalagmite
Palaeogeography, Palaeoclimatology, Palaeoecology,
586
2022
ISSN: 00310182
Publisher: Elsevier B.V.
Keywords:▾
climate change; environmental conditions; interglacial; isotopic ratio; Last Interglacial; precipitation (climatology); rainfall; reconstruction; sedimentation; sedimentation rate; speleothem; stalagmite, Dead Sea; Israel; Jerusalem [Israel]; Levant; Mediterranean Region, Poaceae
Abstract: ▾ The southern Levant region at the fringe of the Saharan-Arabian deserts is particularly vulnerable to warming and desertification, therefore reconstruction of the hydroclimate conditions of this region during periods of past climate change provide important insight on what may occur in the future. Here we report on high temporal resolution 87Sr/86Sr, δ13C and δ18O isotope data of a stalagmite from the Har Nof cave in Jerusalem, demonstrating major climate changes during the last interglacial MIS5e between ~131–116 ka. We combine also data from other caves in Israel and the ICDP Dead Sea deep drill core. The following palaeoenvironmental history is observed: • At 131–127.5 ka, Jerusalem experienced moderate Mediterranean climate conditions. Desert dust accumulated above the cave, while salt deposition occurred in the Dead Sea. • At 127.5–122 ka, across the MIS5e insolation peak and Sapropel S5 interval in the Mediterranean, highly negative speleothem δ18O indicate both Mediterranean and southern (tropical) derived rains. Surface cover diminished, and by 122 ka the 87Sr/86Sr and δ13C values indicate complete soil removal above the cave. Very high temperatures and intensive fires caused the removal of C3 vegetation. The rainfall season shifted from winter to summer with tropical-sourced precipitation. • At 122–120.5 ka, the 87Sr/86Sr ratios indicate contributions of sea salts. Extremely high speleothem δ13C values indicate no vegetation. • At ~120.5–118 ka there was higher rainfall and lower temperatures, associated with re-establishment of vegetation, including savannah-like C4 pioneer grasses that appeared on soil patches. • At 118–116 ka, the sedimentation rate of Har Nof AF12 stalagmite is extremely low, indicating regional aridity, coinciding with massive salt deposition in the Dead Sea. © 2021 Elsevier B.V.
2637.
Frictional stability and hydromechanical coupling of serpentinite-bearing fault gouge
Geophysical Journal International,
231
(1)
290-305
2022
ISSN: 0956540X
Publisher: Oxford University Press
Keywords:▾
Calcite; Earthquakes; Elasticity; Fault slips; Kaolinite; Magnesite; Magnetite; Shear flow, Effective normal stress; Fault gouge; Fault zone; Fault zone rheology; Frictional stability; Hydrological properties; Lizardite; Permeability and porosities; Rheology and friction of fault zones; Serpentinite, Friction, deformation mechanism; earthquake rupture; experimental study; fault gouge; fault slip; fault zone; friction; hydromechanics; microstructure; mineralogy; P-T conditions; permeability; phyllosilicate; porosity; rheology; serpentinite; structural control; triaxial test
Abstract: ▾ Observations of slow earthquakes and tremor have raised fundamental questions about the physics of quasi-dynamic rupture and the underlying fault zone processes. The presence of serpentinite at P-T conditions characteristic of deep tremor and slow earthquakes suggests that it plays an important role in controlling complex fault slip behaviour. Here, we report on experiments designed to investigate the frictional behaviour of serpentinite sampled from outcrop exposures (SO1 and SO2) of altered ultramafic rocks present at depth, and recovered from the SAFOD borehole (G27). XRD analyses reveal the presence of chrisotyle, lizardite, kaolinite, talc in SO1; lizardite, clinochlore and magnetite in SO2; and lizardite, quartz and calcite in G27. We sheared fault gouge in a double-direct shear configuration using a true triaxial deformation apparatus. The effective normal stress was varied from 2 to 40 MPa. We conducted velocity stepping tests and slide-hold-slide (SHS) tests in each experiment to characterize frictional stability and healing. At the end of each experiment, post-shear permeability was measured and the samples were recovered for microstructural analysis. The steady-state friction coefficient was μ = 0.17 for SO1, μ = 0.33 for SO2 and μ = 0.53 for G27. Overall, the gouges exhibit velocity strengthening behaviour, and become nearly velocity neutral at 40 MPa effective normal stress. SHS tests show positive healing rates for SO2 and G27, whereas SO1 exhibits zero or negative healing rates. Permeability decreases with increasing σn', with SO1 (k = 10-20 m2) showing the lowest values. Microstructural observations reveal a well-developed R-Y-P fabric in SO1, which is not observed in SO2 and G27. We posit that the development of shear fabric controlled by mineralogy governs frictional and hydrological properties. In this context, when serpentinite is associated with other weak phyllosilicate minerals, frictional stability and hydrological properties can vary greatly, with a potential control on the mode of fault failure. © 2022 The Author(s) 2022. Published by Oxford University Press on behalf of The Royal Astronomical Society.
2636.
Gas Migration Episodes Observed During Peridotite Alteration in the Samail Ophiolite, Oman
Geophysical Research Letters,
49
(21)
2022
ISSN: 00948276
Publisher: John Wiley and Sons Inc
Keywords:▾
Acoustics; Boreholes; Flow of fluids; Gases; Groundwater; Rocks; Weathering, Arc volcanism; Earthquake process; Free gas; Gas migration; Geosciences; Mantle rocks; Peridotite alterations; Reaction-driven crackings; Serpentinization; Spectra's, Hydrogeology, borehole; earthquake; hydrogeology; hydrophone; migration; serpentinization, Oman
Abstract: ▾ Serpentinization and carbonation of mantle rocks (peridotite alteration) are fundamentally important processes for a spectrum of geoscience topics, including arc volcanism, earthquake processes, chemosynthetic biological communities, and carbon sequestration. Data from a hydrophone array deployed in the Multi-Borehole Observatory (MBO) of the Oman Drilling Project demonstrates that free gas generated by peridotite alteration and/or microbial activity migrates through the formation in discrete bursts of activity. We detected several, minutes-long, swarms of gas discharge into Hole BA1B of the MBO over the course of a 9 month observation interval. The episodic nature of the migration events indicates that free gas accumulates in the permeable flow network, is pressurized, and discharges rapidly into the borehole when a critical pressure, likely associated with a capillary barrier at a flow constriction, is reached. Our observations reveal a dynamic mode of fluid migration during serpentinization, and highlight the important role that free gas can play in modulating pore pressure, fluid flow, and alteration kinetics during peridotite weathering. © 2022. The Authors.
2635.
Geochemical Characterization of the Oman Crust-Mantle Transition Zone, OmanDP Holes CM1A and CM2B
Journal of Geophysical Research: Solid Earth,
127
(4)
2022
ISSN: 21699313
Publisher: John Wiley and Sons Inc
Keywords:▾
crust-mantle boundary; drilling; dunite; geochemistry; harzburgite; partial melting; serpentinization; transition zone, Oman
Abstract: ▾ The transition from the gabbroic oceanic crust to the residual mantle harzburgites of the Oman ophiolite has been drilled at Holes CM1A and CM2B (Wadi Tayin massif) during Phase 2 of the International Continental Scientific Drilling Program Oman Drilling Project (November 2017–January 2018). In order to unravel the formation processes of ultramafic rocks in the Wadi Tayin massif crust-mantle transition zone and deeper in the mantle sections beneath oceanic spreading centers, our study focuses on the whole rock major and trace element compositions (together with CO2 and H2O concentrations) of these ultramafic rocks (56 dunites and 49 harzburgites). Despite extensive serpentinization and some carbonation, most of the trace element contents (REE, HFSE, Ti, Th, U) record high temperature, magmatic process-related signatures. Two major trends are observed, with good correlations between (a) Th and U, Nb and LREE on one hand, and between (b) heavy REE, Ti and Hf on the other hand. We interpret the first trend as the signature of late melt/peridotite interactions as LREE are known to be mobilized by such processes (‘‘lithospheric process’’) and the second trend as the signature of the initial mantle partial melting (‘‘asthenospheric process’’), with little or no overprint from melt/rock reaction events. © 2022. American Geophysical Union. All Rights Reserved.