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Articles 61 - 90 of 215
Full-Text Articles in Geology
The Cenomanian–Turonian Boundary In The Northwestern Part Of The Adriatic Carbonate Platform (Ćićarija Mtn., Istria, Croatia): Characteristics And Implications, Vlatko Brčić, Bosiljka Glumac, Ladislav Fuček, Anita Grizelj, Marija Horvat, Hrvoje Posilović, Ivan Mišur
The Cenomanian–Turonian Boundary In The Northwestern Part Of The Adriatic Carbonate Platform (Ćićarija Mtn., Istria, Croatia): Characteristics And Implications, Vlatko Brčić, Bosiljka Glumac, Ladislav Fuček, Anita Grizelj, Marija Horvat, Hrvoje Posilović, Ivan Mišur
Geosciences: Faculty Publications
The Cenomanian–Turonian boundary (CTB) in the Ćićarija Mountain region (northern Istria, Croatia) is characterized by calcisphere limestone successions with a firmground and glauconite horizon, bioturbated intervals, tempestites, and slumped structures as well as microbially laminated and organic-rich interbeds deposited in the northwestern part of the intra-Tethyan Adriatic Carbonate Platform (AdCP). Compilation of the results from three studied sections (Vodice–Jelovica, Martinjak and Planik) of litho-, bio-, and microfacies analyses, X-ray diffraction, SEM, EDS, and stable isotope analyses allowed reconstruction of marine paleoenvironmental conditions during this time period. Shallow-marine carbonate deposits of the Milna Formation underlie a drowned-platform succession of the Sveti …
Age And Intraspecific Diversity Of Resilient Acropora Communities In Belize, Adele Irwin, Lisa Greer, Robert Humston, Meghann Devlin-Durante, Paul Cabe, Halard Lescinsky, Karl Wirth, H. Allen Curran, Iliana B. Baums
Age And Intraspecific Diversity Of Resilient Acropora Communities In Belize, Adele Irwin, Lisa Greer, Robert Humston, Meghann Devlin-Durante, Paul Cabe, Halard Lescinsky, Karl Wirth, H. Allen Curran, Iliana B. Baums
Geosciences: Faculty Publications
The corals Acropora palmata and A. cervicornis are important Caribbean reef-builders that have faced significant mortality in recent decades. While many studies have focused on the recent demise of these species, data from areas where Acropora spp. have continued to thrive are limited. Understanding the genetic diversity, recruitment, and temporal continuity of healthy populations of these threatened Acropora spp. and the hybrid they form (“Acropora prolifera”) may provide insights into the demographic processes governing them. We studied three reef sites with abundant A. cervicornis, A. palmata, and hybrid Acropora populations offshore of Ambergris Caye, Belize at …
Mechanical Models Favor A Ramp Geometry For The Ventura-Pitas Point Fault, California, Scott T. Marshall, Gareth J. Funning, Hannah E. Kreuger, Susan E. Owen, John P. Loveless
Mechanical Models Favor A Ramp Geometry For The Ventura-Pitas Point Fault, California, Scott T. Marshall, Gareth J. Funning, Hannah E. Kreuger, Susan E. Owen, John P. Loveless
Geosciences: Faculty Publications
Recent investigations have provided new and significantly revised constraints on the subsurface structure of the Ventura-Pitas Point fault system in southern California; however, few data directly constrain fault surfaces below ~6 km depth. Here, we use geometrically complex three-dimensional mechanical models driven by current geodetic strain rates to test two proposed subsurface models of the fault system. We find that the model that incorporates a ramp geometry for the Ventura-Pitas Point fault better reproduces both the regional long term geologic slip rate data and interseismic GPS observations of uplift in the Santa Ynez Mountains. The model-calculated average reverse slip rate …
Super-Interseismic Periods: Redefining Earthquake Recurrence, John P. Loveless
Super-Interseismic Periods: Redefining Earthquake Recurrence, John P. Loveless
Geosciences: Faculty Publications
Precise geodetic measurements made over broad swaths of tectonically active regions record patterns of interseismic strain accumulation, providing key insights into the locus and timing of pending earthquakes. Recent studies of geodetic position time series, including that of Melnick et al. (2017), illustrate temporal variation in the pattern of interseismic deformation. These authors propose that the 2010 Mw = 8.8 Maule, Chile, earthquake enhanced coupling on the Andean subduction zone adjacent to the rupture, including on the portion of the megathrust that broke 5 years later in the Mw = 8.3 Illapel event.
Callianassid Shrimp Diversity Around San Salvador Island, Bahamas: Why Marine Biologists And Geologists Should Care, H. Allen Curran, Koji Seike
Callianassid Shrimp Diversity Around San Salvador Island, Bahamas: Why Marine Biologists And Geologists Should Care, H. Allen Curran, Koji Seike
Geosciences: Faculty Publications
Reprinted from: Carol L. Landry, Lee J. Florea, & Daniel S. Kjar (eds.), Proceedings of the 1st Joint Symposium on the Natural History and Geology of The Bahamas: San Salvador, Gerace Research Centre
Post-Rift Magmatic Evolution Of The Eastern North American “Passive-Aggressive” Margin, Sarah E. Mazza, Esteban Gazel, Elizabeth A. Johnson, Michael Bizimis, Ryan Mcaleer, C. Berk Biryol
Post-Rift Magmatic Evolution Of The Eastern North American “Passive-Aggressive” Margin, Sarah E. Mazza, Esteban Gazel, Elizabeth A. Johnson, Michael Bizimis, Ryan Mcaleer, C. Berk Biryol
Geosciences: Faculty Publications
Understanding the evolution of passive margins requires knowledge of temporal and chemical constraints on magmatism following the transition from supercontinent to rifting, to post-rifting evolution. The Eastern North American Margin (ENAM) is an ideal study location as several magmatic pulses occurred in the 200 My following rifting. In particular, the Virginia-West Virginia region of the ENAM has experienced two postrift magmatic pulses at ∼152 Ma and 47 Ma, and thus provides a unique opportunity to study the long-term magmatic evolution of passive margins. Here we present a comprehensive set of geochemical data that includes new Ar/ Ar ages, major and …
Imaging Bioturbation In Supratidal Carbonates: Non-Invasive Field Techniques Enhance Neoichnological And Zoogeomorphological Research, San Salvador, The Bahamas, Karen Kopcznski, Ilya Buynevich, H. Allen Curran, Jon Caris, Jonathan Nyquist
Imaging Bioturbation In Supratidal Carbonates: Non-Invasive Field Techniques Enhance Neoichnological And Zoogeomorphological Research, San Salvador, The Bahamas, Karen Kopcznski, Ilya Buynevich, H. Allen Curran, Jon Caris, Jonathan Nyquist
Geosciences: Faculty Publications
A case study in unconsolidated carbonates on San Salvador Island, The Bahamas, utilized high-frequency (800 MHz) georadar imaging to augment existing methodologies (burrow counts and measurements, casting) in brachyuran bioturbation research (Ocypode quadrata and Gecarcinus lateralis), and as part of a new dataset characterizing blue land crab (Cardisoma guanhumi) burrows. Non-invasive techniques such as ground-penetrating radar (GPR) can complement traditional field surveys aimed at quantifying mesoscale bioturbation in modern settings. These methods can establish diagnostic features for tracemaker identification and refine existing ichnofacies models. Drone-mounted aerial coverage provided the first high-resolution images of the micro-topography and …
Slip Distribution Of The 2014 Mw=8.1 Pisagua, Northern Chile, Earthquake Sequence Estimated From Coseismic Fore-Arc Surface Cracks, John P. Loveless, Chelsea P. Scott, Richard W. Allmendinger, Gabriel González
Slip Distribution Of The 2014 Mw=8.1 Pisagua, Northern Chile, Earthquake Sequence Estimated From Coseismic Fore-Arc Surface Cracks, John P. Loveless, Chelsea P. Scott, Richard W. Allmendinger, Gabriel González
Geosciences: Faculty Publications
The 2014 Mw = 8.1 Iquique (Pisagua), Chile, earthquake sequence ruptured a segment of the Nazca-South America subduction zone that last hosted a great earthquake in 1877. The sequence opened >3700 surface cracks in the fore arc of decameter-scale length and millimeter-to centimeter-scale aperture. We use the strikes of measured cracks, inferred to be perpendicular to coseismically applied tension, to estimate the slip distribution of the main shock and largest aftershock. The slip estimates are compatible with those based on seismic, geodetic, and tsunami data, indicating that geologic observations can also place quantitative constraints on rupture properties. The earthquake sequence …
Interseismic Deformation And Moment Deficit Along The Manila Subduction Zone And The Philippine Fault System, Ya-Ju Hsu, Shui-Beih Yu, John P. Loveless, Teresito Bacolcol, Renato Solidum, Artemio Luis Jr., Alfie Pelicano, Jochen Woessner
Interseismic Deformation And Moment Deficit Along The Manila Subduction Zone And The Philippine Fault System, Ya-Ju Hsu, Shui-Beih Yu, John P. Loveless, Teresito Bacolcol, Renato Solidum, Artemio Luis Jr., Alfie Pelicano, Jochen Woessner
Geosciences: Faculty Publications
We examine interseismic coupling of the Manila subduction zone and fault activity in the Luzon area using a block model constrained by GPS data collected from 1998 to 2015. Estimated long-term slip rates along the Manila subduction zone show a gradual southward decrease from 90–100 mm/yr at the northwest tip of Luzon to 65–80 mm/yr at the southern portion of the Manila Trench. We provide two block models (models A and B) to illustrate possible realizations of coupling along the Manila Trench, which may be used to infer future earthquake rupture scenarios. Model A shows a low coupling ratio …
Extinction Intensity, Selectivity And Their Combined Macroevolutionary Influence In The Fossil Record, Jonathan L. Payne, Andrew M. Bush, Ellen T. Chang, Noel A. Heim, Matthew L. Knope, Sara B. Pruss
Extinction Intensity, Selectivity And Their Combined Macroevolutionary Influence In The Fossil Record, Jonathan L. Payne, Andrew M. Bush, Ellen T. Chang, Noel A. Heim, Matthew L. Knope, Sara B. Pruss
Geosciences: Faculty Publications
The macroevolutionary effects of extinction derive from both intensity of taxonomic losses and selectivity of losses with respect to ecology, physiology and/or higher taxonomy. Increasingly, palaeontologists are using logistic regression to quantify extinction selectivity because the selectivity metric is independent of extinction intensity and multiple predictor variables can be assessed simultaneously. We illustrate the use of logistic regression with an analysis of physiological buffering capacity and extinction risk in the Phanerozoic marine fossil record. We propose the geometric mean of extinction intensity and selectivity as a metric for the influence of extinction events. The end-Permian mass extinction had the largest …
Contrasting Sediment Melt And Fluid Signatures For Magma Components In The Aeolian Arc: Implications For Numerical Modeling Of Subduction Systems, Denis Zamboni, Esteban Gazel, Jeffrey G. Ryan, Claudia Cannatelli, Federico Lucchi, Zachary D. Atlas, Jarek Trela, Sarah E. Mazza, Benedetto De Vivo
Contrasting Sediment Melt And Fluid Signatures For Magma Components In The Aeolian Arc: Implications For Numerical Modeling Of Subduction Systems, Denis Zamboni, Esteban Gazel, Jeffrey G. Ryan, Claudia Cannatelli, Federico Lucchi, Zachary D. Atlas, Jarek Trela, Sarah E. Mazza, Benedetto De Vivo
Geosciences: Faculty Publications
The complex geodynamic evolution of Aeolian Arc in the southern Tyrrhenian Sea resulted in melts with some of the most pronounced along the arc geochemical variation in incompatible trace elements and radiogenic isotopes worldwide, likely reflecting variations in arc magma source components. Here we elucidate the effects of subducted components on magma sources along different sections of the Aeolian Arc by evaluating systematics of elements depleted in the upper mantle but enriched in the subducting slab, focusing on a new set of B, Be, As, and Li measurements. Based on our new results, we suggest that both hydrous fluids and …
Two Decades Of Spatiotemporal Variations In Subduction Zone Coupling Offshore Japan, John P. Loveless, Brendan J. Meade
Two Decades Of Spatiotemporal Variations In Subduction Zone Coupling Offshore Japan, John P. Loveless, Brendan J. Meade
Geosciences: Faculty Publications
Spatial patterns of interplate coupling on global subduction zones can be used to guide seismic hazard assessment, but estimates of coupling are often constrained using a limited temporal range of geodetic data. Here we analyze ∼19 years of geodetic observations from the GEONET network to assess time-dependent variations in the spatial distribution of coupling on the subduction zones offshore Japan. We divide the position time series into five, ∼3.75-year epochs each decomposed into best-fit velocity, annual periodic signals, coseismic offsets, and postseismic effects following seven major earthquakes. Nominally interseismic velocities are interpreted in terms of a combination of tectonic block …
A High-Resolution Mid-Pleistocene Temperature Record From Arctic Lake El'gygytgyn: A 50 Kyr Super Interglacial From Mis 33 To Mis 31?, Gregory De Wet, Isla S. Castañeda, Robert M. Deconto, Julie Brigham-Grette
A High-Resolution Mid-Pleistocene Temperature Record From Arctic Lake El'gygytgyn: A 50 Kyr Super Interglacial From Mis 33 To Mis 31?, Gregory De Wet, Isla S. Castañeda, Robert M. Deconto, Julie Brigham-Grette
Geosciences: Faculty Publications
Previous periods of extreme warmth in Earth's history are of great interest in light of current and predicted anthropogenic warming. Numerous so called "super interglacial" intervals, with summer temperatures significantly warmer than today, have been identified in the 3.6 million year (Ma) sediment record from Lake El'gygytgyn, northeast Russia. To date, however, a high-resolution paleotemperature reconstruction from any of these super interglacials is lacking. Here we present a paleotemperature reconstruction based on branched glycerol dialkyl glycerol tetraethers (brGDGTs) from Marine Isotope Stages (MIS) 35 to MIS 29, including super interglacial MIS 31. To investigate this period in detail, samples were …
Documentation Of Extensive Root Systems Of Thalassia Seagrass Along The Banks Of Pigeon Creek, San Salvador Island, Bahamas, Bosiljka Glumac, H. Allen Curran
Documentation Of Extensive Root Systems Of Thalassia Seagrass Along The Banks Of Pigeon Creek, San Salvador Island, Bahamas, Bosiljka Glumac, H. Allen Curran
Geosciences: Faculty Publications
Reprinted from: Bosiljka Glumac & Michael Savarese (eds.), Proceedings of the 16th Symposium on the Geology of the Bahamas and Other Carbonate Regions: San Salvador, Gerace Research Center
Modern And Fossil Callianassid Burrows Of The Bahamas: Comparisons And Implications For Paleoenvironmental Analysis, H. Allen Curran, Koji Seike
Modern And Fossil Callianassid Burrows Of The Bahamas: Comparisons And Implications For Paleoenvironmental Analysis, H. Allen Curran, Koji Seike
Geosciences: Faculty Publications
Reprinted from: Bosiljka Glumac & Michael Savarese (eds.), Proceedings of the 16th Symposium on the Geology of the Bahamas and Other Carbonate Regions:San Salvador, Gerace Research Center
Quantifying Exceptionally Large Populations Of Acropora Spp. Corals Off Belize Using Sub-Meter Satellite Imagery Classification, James Busch, Lisa Greer, David Harbor, Karl Wirth, Halard Lescinsky, H. Allen Curran, Kirsten De Beurs
Quantifying Exceptionally Large Populations Of Acropora Spp. Corals Off Belize Using Sub-Meter Satellite Imagery Classification, James Busch, Lisa Greer, David Harbor, Karl Wirth, Halard Lescinsky, H. Allen Curran, Kirsten De Beurs
Geosciences: Faculty Publications
Caribbean coral reefs have experienced dramatic declines in live coral cover in recent decades. Primary branching framework Caribbean corals, Acropora cervicornis (Lamarck, 1816) and Acropora palmata (Lamarck, 1816), have suffered the greatest collapse. Coral Gardens, Belize, is one of few remaining, and perhaps the largest, refugia for abundant, healthy, but undocumented populations of both Acropora species in the Caribbean Sea. In the present study, GeoEye-1 multispectral satellite imagery of a 25 km2 reefal area near Ambergris Caye, Belize, was analyzed to identify live Acropora spp. cover. We used a supervised classification to predict occurrence of areas with live Acropora spp. …
Origin Of Late Holocene Strandplains In The Southern Exuma Islands, Bahamas: Progradation, Ephemeral Highstands, And Storminess, Michael Savarese, H. Allen Curran
Origin Of Late Holocene Strandplains In The Southern Exuma Islands, Bahamas: Progradation, Ephemeral Highstands, And Storminess, Michael Savarese, H. Allen Curran
Geosciences: Faculty Publications
Reprinted from: Bosiljka Glumac & Michael Savarese (eds.), Proceedings of the16th Symposium on the Geology of the Bahamas and Other Carbonate Regions:San Salvador, Gerace Research Center
Subaerial Seeps On Holocene Carbonate Eolian Strata From Cat Island, Bahamas, Bosiljka Glumac, H. Allen Curran, Sarah Brisson
Subaerial Seeps On Holocene Carbonate Eolian Strata From Cat Island, Bahamas, Bosiljka Glumac, H. Allen Curran, Sarah Brisson
Geosciences: Faculty Publications
Reprinted from: Bosiljka Glumac & Michael Savarese (eds.),Proceedings of the 16th Symposium of the Geology of the Bahamas and Other Carbonate Regions: San Salvador, Gerace Research Center
Upper Plate Reverse Fault Reactivation And The Unclamping Of The Megathrust During The 2014 Northern Chile Earthquake Sequence, Gabriel González, Pablo Salazar, John P. Loveless, Richard W. Allmendinger, Felipe Aron, Mahesh Shrivastava
Upper Plate Reverse Fault Reactivation And The Unclamping Of The Megathrust During The 2014 Northern Chile Earthquake Sequence, Gabriel González, Pablo Salazar, John P. Loveless, Richard W. Allmendinger, Felipe Aron, Mahesh Shrivastava
Geosciences: Faculty Publications
After 137 years without a great earthquake, the Mw 8.1 Pisagua event of 1 April 2014 occurred in the central portion of the southern Peru–northern Chile subduction zone. This megathrust earthquake was preceded by more than 2 weeks of foreshock activity migrating ∼3.5 km/day toward the mainshock hypocenter. This foreshock sequence was triggered by an Mw 6.7 earthquake on a reverse fault in the upper plate that strikes at a high angle to the trench, similar to well-documented reverse faults onshore. These margin-oblique reverse faults accommodate north-south shortening resulting from subduction across a plate boundary that is curved in map …
Fossils Of Putative Marine Algae From The Cryogenian Glacial Interlude Of Mongolia, Phoebe A. Cohen, Francis A. Macdonald, Sara Pruss, Emily Matys, Tanja Bosak
Fossils Of Putative Marine Algae From The Cryogenian Glacial Interlude Of Mongolia, Phoebe A. Cohen, Francis A. Macdonald, Sara Pruss, Emily Matys, Tanja Bosak
Geosciences: Faculty Publications
Neoproterozoic carbonate successions provide a new taphonomic window into the diversification of eukaryotes. We report recently discovered macroscopic organic warty sheets (MOWS) in macerates of limestone from the ca. 662-635 Ma Taishir Formation (Tsagaan Olom Group, Mongolia). Sheets are applanate. One surface contains raised ridges and conspicuous, ∼ 100-μm-tall warty protuberances with depressed tops that enclose internal cavities containing cellular structures. The Taishir MOWS may be the remains of unusual bacterial, protistan, or fungal biofilms, or a previously undocumented, extinct taxon. However, multiple lines of evidence including the morphology of warty protuberances and the presence of cellular architecture within protuberances …
Sinuous Rhizoliths Mimic Invertebrate Trace Fossils On Upper Pleistocene Caliche Surfaces, San Salvador Island, Bahamas, H. Allen Curran
Sinuous Rhizoliths Mimic Invertebrate Trace Fossils On Upper Pleistocene Caliche Surfaces, San Salvador Island, Bahamas, H. Allen Curran
Geosciences: Faculty Publications
The Pleistocene–Holocene boundary on islands of the Bahama Archipelago is typically marked by a calichified paleosol horizon that formed on exposed limestone surfaces during lowered sea level of the Last Glacial. On the north coast of San Salvador, an extensive laminar caliche surface is present west of Singer Bar Point. Formed on Upper Pleistocene (Eemian) carbonate eolianite and overlain by Holocene eolianite, this surface bears numerous and distinctive large, sinuous structures typically preserved in half relief, and with sharp, parallel ridge-like edges that slope inward to form a smooth, medial ‘trough’ having widths mostly between 1 and 3 cm. Individual …
Kinematic Barrier Constraints On The Magnitudes Of Additional Great Earthquakes Off The East Coast Of Japan, John P. Loveless, Brendan J. Meade
Kinematic Barrier Constraints On The Magnitudes Of Additional Great Earthquakes Off The East Coast Of Japan, John P. Loveless, Brendan J. Meade
Geosciences: Faculty Publications
No abstract provided.
Taphonomic Bias Of Selective Silicification Revealed By Paired Petrographic And Insoluble Residue Analysis, Sara B. Pruss, Jonathan L. Payne, Sophie Westacott
Taphonomic Bias Of Selective Silicification Revealed By Paired Petrographic And Insoluble Residue Analysis, Sara B. Pruss, Jonathan L. Payne, Sophie Westacott
Geosciences: Faculty Publications
Silicification is an important mode of fossil preservation but the extent to which silicified material represents an unbiased sampling of the total fossil assemblage within a given rock sample remains poorly quantified. Here, we use paired analyses of thin sections and acid-extracted silicified specimens from the same samples to examine the biases introduced during silicification of Lower Triassic Virgin Limestone carbonates preserved in the Muddy Mountains of southern Nevada. Bivalves dominate most thin sections in the point count data, but rarely silicify completely enough to be recognized in residue. Echinoderms and gastropods are less abundant in thin section but dominate …
Total Variation Regularization Of Geodetically And Geologically Constrained Block Models For The Western United States, Eileen L. Evans, John P. Loveless, Brendan J. Meade
Total Variation Regularization Of Geodetically And Geologically Constrained Block Models For The Western United States, Eileen L. Evans, John P. Loveless, Brendan J. Meade
Geosciences: Faculty Publications
Geodetic observations of interseismic deformation in the Western United States provide con- straints on microplate rotations, earthquake cycle processes, and slip partitioning across the Pacific–North America Plate boundary. These measurements may be interpreted using block models, in which the upper crust is divided into microplates bounded by faults that accumulate strain in a first-order approximation of earthquake cycle processes. The number and geometry of microplates are typically defined with boundaries representing a limited subset of the large number of potentially seismogenic faults. An alternative approach is to include a large number of potentially active faults bounding a dense array of …
Burrow Morphology Of The Land Crab Gecarcinus Lateralis And The Ghost Crab Ocypode Quadrata On San Salvador Island, The Bahamas: Comparisons And Palaeoenvironmental Implications, Koji Seike, H. Allen Curran
Burrow Morphology Of The Land Crab Gecarcinus Lateralis And The Ghost Crab Ocypode Quadrata On San Salvador Island, The Bahamas: Comparisons And Palaeoenvironmental Implications, Koji Seike, H. Allen Curran
Geosciences: Faculty Publications
Burrow morphologies of the land crab Gecarcinus lateralis and the ghost crab Ocypode quadrata were investigated on East Beach, San Salvador Island, The Bahamas, with the goals of critical comparison of their morphologies and of clarifying and advancing their palaeoenvironmental usefulness. In comparing land crab burrows to those of the ghost crab, the former are simpler but more variable in overall shape. G. lateralis burrows have a more compressed form in the transverse section of the burrow shaft and possess lower (more horizontal) shaft inclination than those of O. quadrata. In the late Holocene backshore and dune deposits on San …
Stable Isotopic (Δ13C And Δ18O) Signatures Of Biogenic Calcretes Marking Discontinuity Surfaces: A Case Study From Upper Cretaceous Carbonates Of Central Dalmatia And Eastern Istria, Croatia, Mihovil Brlek, Bosiljka Glumac
Stable Isotopic (Δ13C And Δ18O) Signatures Of Biogenic Calcretes Marking Discontinuity Surfaces: A Case Study From Upper Cretaceous Carbonates Of Central Dalmatia And Eastern Istria, Croatia, Mihovil Brlek, Bosiljka Glumac
Geosciences: Faculty Publications
Biogenic calcretes associated with a regional Cretaceous to Paleogene subaerial unconformity and an intraformational composite (polygenic) surface in Upper Cretaceous intra-platform peritidal successions in central Dalmatia and eastern Istria, Croatia (Adriatic-Dinaridic Carbonate Platform), were analyzed for their δ13C and δ18O signatures in order to provide insight into the conditions of subaerial exposure and calcrete development. The distinctly negative δ13C signatures of biogenic calcretes marking the regional subaerial unconformity differ considerably from the δ13C values of the host marine limestones. This indicates carbon isotope exchange of primary marine CaCO3 with CO2 released by root and rhizomicrobial respiration and subsequent precipitation of …
Discontinuity Surfaces In Upper Cretaceous To Paleogene Carbonates Of Central Dalmatia (Croatia): Glossifungites Ichnofacies, Biogenic Calcretes, And Stratigraphic Implications, Mihovil Brlek, Tvrtko Korbar, Adrijan Košir, Bosiljka Glumac, Anita Grizelj, Bojan Otoničar
Discontinuity Surfaces In Upper Cretaceous To Paleogene Carbonates Of Central Dalmatia (Croatia): Glossifungites Ichnofacies, Biogenic Calcretes, And Stratigraphic Implications, Mihovil Brlek, Tvrtko Korbar, Adrijan Košir, Bosiljka Glumac, Anita Grizelj, Bojan Otoničar
Geosciences: Faculty Publications
Substrate-controlled ichnofacies and biogenic calcretes represent key features for identification and interpretation of discontinuities in the carbonate rock record, which are of great significance for stratigraphic interpretations and correlations. Intraformational firmground and composite surfaces, as well as a regional Cretaceous to Paleogene (K-Pg) subaerial unconformity, developed in Upper Cretaceous to Paleogene intra-platform peritidal successions in central Dalmatia, Croatia (Adriatic-Dinaridic Carbonate Platform, ADCP), were analyzed for their trace fossil and subaerial exposure features. Thalassinoides (probably T. paradoxicus) box-work burrow systems of the substrate-controlled Glossifungites ichnofacies characterize the two documented firmgrounds and one composite (polygenic) surface. Rhizogenic laminar calcretes developed subsequently inside …
Ichnogenic Megaporosity And Permeability In Carbonate Aquifers And Reservoirs: Definitions And Examples, H. Allen Curran, Kevin J. Cunningham
Ichnogenic Megaporosity And Permeability In Carbonate Aquifers And Reservoirs: Definitions And Examples, H. Allen Curran, Kevin J. Cunningham
Geosciences: Faculty Publications
Biogenic megaporosity in sedimentary deposits (readily visible without magnification) typically has body-fossil moldic or ichnogenic origin. We consider ichnogenic megaporosity as pores greater than 4 mm associated with either burrow- or rhizolith-dominated ichnofabrics. Dominant bioturbators in shallow-marine environments typically include thalassinidean crustaceans and polychaetes. Callianassid shrimp commonly dominate the deep-tier fauna in carbonate and siliciclastic, sandy, shallow-marine settings; when fossilized their thickly lined, pelleted burrows (cm-scale outside diameters) are assigned to the ichnogenus Ophiomorpha. In the mostly Pleistocene carbonate rocks of the Biscayne aquifer of south Florida, Ophiomorpha is well lithified and burrows form a rigid framework, with interburrow macroporosity …
Stratigraphic Framework, Discontinuity Surfaces, And Regional Significance Of Campanian Slope To Ramp Carbonates From Central Dalmatia, Croatia, M. Brlek, T. Korbar, B. Cvetko Tešović, B. Glumac, L. Fuček
Stratigraphic Framework, Discontinuity Surfaces, And Regional Significance Of Campanian Slope To Ramp Carbonates From Central Dalmatia, Croatia, M. Brlek, T. Korbar, B. Cvetko Tešović, B. Glumac, L. Fuček
Geosciences: Faculty Publications
The sedimentology, microfacies, and stratigraphic age (from planktonic and benthic foraminifera and strontium-isotope stratigraphy) of a 300-m-thick Upper Cretaceous carbonate succession from the Island of Čiovo (central Dalmatia, Croatia) were analyzed in order to determine the lithostratigraphic, depositional, and chronostratigraphic framework. The Cretaceous strata were deposited in the southern part of the long-lasting (Late Triassic to Paleogene) Adriatic-Dinaridic Carbonate Platform (ADCP), one of a few late Mesozoic, intra-Tethyan, peri-Adriatic (sub)tropical archipelagos. The succession is separated by a firmground formational boundary into two lithostratigraphic units: the underlying Middle to Upper Campanian Dol Formation consisting of slope pelagic limestone with intercalated turbidites …
Preservational And Morphological Variability Of Assemblages Of Agglutinated Eukaryotes In Cryogenian Cap Carbonates Of Northern Namibia, Lilly A. Dalton, Tanja Bosak, Francis A. Macdonald, Daniel J.G. Lahr, Sara B. Pruss
Preservational And Morphological Variability Of Assemblages Of Agglutinated Eukaryotes In Cryogenian Cap Carbonates Of Northern Namibia, Lilly A. Dalton, Tanja Bosak, Francis A. Macdonald, Daniel J.G. Lahr, Sara B. Pruss
Geosciences: Faculty Publications
Laminated carbonates of the Rasthof Formation, deposited in the aftermath of the early Cryogenian low-latitude glaciation (Sturtian, 717-662 Ma), preserve abundant round tests of agglutinated microscopic eukaryotes. Previously, fossil tests were reported in two localities (Ongongo and Okaaru) from microbially laminated carbonates in the Rasthof Formation, which revealed a previous unexplored Cryogenian taphonomic window. In order to better understand the lateral variability in these microfossil assemblages, this work systematically examines fossil tests from two additional localities, South Ombepera and Ombepera, and compares their preservation in thinly and thickly laminated microbial laminites. Cap carbonates in South Ombepera and Ombepera contain abundant, …