We review scientific ocean drilling of the New Jersey passive continental margin and the success of Integrated Ocean Drilling Program (IODP1) Expedition 313 in addressing long-standing, fundamental issues of sequence stratigraphy, sea-level change, and resources. The New Jersey margin was targeted for study by several gener-ations of ocean drilling because of its thick, prograding Oligocene to Quaternary sequences bounded by un-conformities. Coring and logging on the onshore coastal plain (Ocean Drilling Program [ODP] Legs 150Xh ttp://www-odp.tamu.edu/publications/citations/cite150X.htmland 174AX), outer continental shelf (Leg 174A), and continental slope and rise (Legs 95, 150, and 174A) provided a chronology of sea-level lowerings but did not sample facies needed to evaluate Miocene sea-level amplitudes. Expedition 313 used a Mission Specific Platform (L/B Kayd) to drill on the shallow continental shelf, recover critical Miocene facies, particularly on clinoform foresets, and capture the full amplitudes of relative sea-level changes. Expedition 313 overcame challenging borehole conditions and recovered a total of 1311 m of core at three sites (81 % recovery) that: (1) correlated difficult-to-date nearshore-shelf facies to the time scale with resolution better than +/- 0.5 million years (Myr); (2) tested and confirmed that sequence boundaries are a primary cause of seismic reflections on siliciclastic shelves;(3) tested sequence stratigraphic models with core-log-seismic integration; and. (4) provided a record of paleodepth changes through time that constrained amplitudes of Miocene sea-level change, including the influence of mantle dynamic topography. The New Jersey relative sea-level estimates are similar to those obtained using stable isotopes and Mg/Ca paleothermometry, showing that GMGSL ("eustasy") varied with 10-60 m scale amplitudes on the Myr scale. Drilling beneath the shallow continental shelf also identified groundwater sources, including seawater, deep- sourced brines, and meteoric fresh water, that represent potential resources for future generations. Studies of this margin have implications for future subsurface storage of supercritical CO2 and geotechnical issues relating to the location of offshore wind infrastructure. Expedition 313 demonstrated the feasibility of continuously recovering and logging strata in shallow water, providing constraints on sea level, sequences, hydrogeology, and resources
The New Jersey, USA, continental margin has become a natural laboratory for studying sediment dynamics and sequence architecture associated with eustatic rhythms. We collected 564 km2 of ultrahigh-resolution 3-D seismic data in the region of Integrated Ocean Drilling Program Expedition 313 to investigate the formation of the shelf and clinoform system during early to middle Miocene time. We identified 22 high-frequency sequences and 76 systems tracts, using a geometric breakdown approach based on changes in the landward and seaward terminations and elevation of clinoform rollovers in successive reflector packages. Predicted petrophysical properties of acoustic impedance, P-wave velocity, density, and clay content show rhythmic patterns that follow the seismic sequence architecture, with landward fining in transgressive deposits and basinward fining in other systems tracts. Similar proportions of lowstand, transgressive, and highstand deposits suggest that sediment accumulated during periods of both rise and fall in relative sea level, with a low proportion of falling-stage deposits (4%), which suggests that forced regression rarely exposed clinoform breakpoints. Maximum dip azimuths for the Miocene section indicate southwestward sediment transport, broadly along strike of the margin. Enhanced sediment accumulation to the southwest caused a 13° anticlockwise rotation in clinoform orientation after the late Oligocene, and this uneven stress load influenced the orientation of contemporary polygonal faults on basinward parts of the clinoforms. In contrast to models that emphasize downslope sediment transport in margin development, we highlight the importance of along-shore advective processes in shaping the New Jersey margin during the Miocene.
Accommodation space governs the spatial and temporal distributions of sediments in continental margins. Mapping the sedimentation patterns, therefore, offers insights into the solid-Earth processes that shape accommodation space. We assembled an unprecedented amount of seismic and borehole data along the Eastern North American Margin and used it to divide the margin's sedimentary package into eight chronostratigraphic intervals, identifying temporal shifts in depocenters under the continental shelf, slope, and rise. The Jurassic depocenters follow the syn-rift structure and its thermal subsidence loci. The Long Island Platform is the only margin segment where the early post-rift sediment thickness matches subsidence predictions from uniform-stretching models, whereas in Georges Bank Basin (GBB) and Baltimore Canyon Trough (BCT), sediment thickness is 1.5-3 times higher than predicted, pointing to other factors at play. A margin-wide Jurassic transient shoulder uplift is inferred from the occurrence of stratigraphic onlaps above thinned crust. Unlike the Jurassic, the Cretaceous and Cenozoic depocenters disregard the inherited subsidence pattern. The accommodation space over the shelf and coastal plain during the Cretaceous was affected by regional isostatic compensation of the sedimentary loads accumulated on the shelf and rise. Accommodation space development in the GBB was interrupted during the Cretaceous after the margin crossed the Great Meteor Hotspot track, resulting in a widespread permanent uplift, erosion, and sediment redistribution. The distribution of anomalous Neogene subsidence in the BCT challenges previous suggestions of mantle dynamic control on the accommodation space and favors flexural downwarping of the shelf by sediment accumulation on the rise. The volume available for sediment accumulation at continental margins is key for determining where, when and how much sediments are stored. To explore the processes that determine this volume we assembled a broad geological and geophysical data set that covers the US Atlantic margin from Cape Hatteras to the US-Canada border. Using these data, the margin's sedimentary cover was divided into eight time-constrained intervals spanning the last similar to 190 Myr. The thickness distribution of these intervals was used to investigate the processes that regulated the space available for sediment accumulation. During the first similar to 50 Myr of the margin life span, most of the deposition occurred over areas that were thinned and heated during the margin's formation and later cooled and subsided. During this period, the deepest parts of the margin subsided twice as fast as predicted by conventional models whereas the margin's inland rims experienced uplift. Later, subsidence of the coastal plain by basinward sediment loading allowed sediment accumulation. The passage of the margin over a deep-seated thermal anomaly resulted in uplift and erosion. An anomalous Neogene sediment accumulation on the continental shelf is explained by subsidence inflicted by seaward sediment loading. We present a new stratigraphic framework for the post-rift period of the US Atlantic margin The syn-rift shaping of the lithosphere is key for determining accommodation space during the post-rift period Observed deviations from passive thermal subsidence patterns resulted from flexure, hot spot passage, flank uplift or mantle dynamics
The presence and suitability of carbon storage reservoirs in the Georges Bank Basin (GBB; offshore Massachusetts) is evaluated through the application of sequence stratigraphy and the construction of a static earth model using those interpretations and physical properties measurements. Sequence stratigraphy is applied using well logs and similar to 60,000 km (similar to 37,200 mi) of multichannel seismic profiles to delineate six thick (>100 m [>330 ft]) Lower Cretaceous fluvial-deltaic depositional sequences. Two composite Missisauga sequences (MS2 and MS1; Berriasian to Barremian) comprise the lowermost prospective storage resource that may store 4.2-8.4 Gt (2% and 4% efficiency factors) of supercritical CO2 beneath the confining Naskapi shale. These heterolithic, fluvial sandstones comprise thinner and less laterally expansive sand bodies than the deltaic sandstones within three overlying Logan Canyon sequences (LC3, LC2, and LC1; Aptian to Upper Cenomanian). The Logan Canyon sequences comprise a prospective storage resource of 9.7-19.5 Gt sealed by the overlying Dawson Canyon shale. Combined, these Lower Cretaceous strata represent storage resources of similar to 14 to 28 Gt in the GBB. The 38-76 Gt of total reservoir resources in Lower Cretaceous sandstones in the Baltimore Canyon Trough to the south, coupled with a closer proximity to emissions sources and better refinement of reservoir characterization for those strata, renders the GBB an unlikely location for initial adoption of offshore carbon capture and storage (CCS) regionally. However, storage resources in the GBB are of significant value if CCS is to be adopted at a scale impactful to mitigating the effect of anthropogenic emissions on atmospheric CO2 concentrations.
On 5 April 2024, 10:23 a.m. local time, a moment magnitude 4.8 earthquake struck Tewksbury Township, New Jersey, about 65 km west of New York City. Millions of people from Virginia to Maine and beyond felt the ground shaking, resulting in the largest number (>180,000) of U.S. Geological Survey (USGS) “Did You Feel It?” reports of any earthquake. A team deployed by the Geotechnical Extreme Events Reconnaissance Association and the National Institute of Standards and Technology documented structural and nonstructural damage, including substantial damage to a historic masonry building in Lebanon, New Jersey. The USGS National Earthquake Information Center reported a focal depth of about 5 km, consistent with a lack of signal in Interferometric Synthetic Aperture Radar data. The focal mechanism solution is strike slip with a substantial thrust component. Neither mechanism’s nodal plane is parallel to the primary northeast trend of geologic discontinuities and mapped faults in the region, including the Ramapo fault. However, many of the relocated aftershocks, for which locations were augmented by temporary seismic deployments, form a cluster that parallels the general northeast trend of the faults. The aftershocks lie near the Tewksbury fault, north of the Ramapo fault.
We produced a 10 Myr synthetic stratigraphic section using a forward stratigraphic model that generates marine deltaic stratigraphy over geological timescales. We recursively fit the model using a Bayesian inversion algorithm to test: (1) if it could be accurately reconstructed; (2) if the parameters used to create it could be recovered; and (3) the sensitivity of the model output to given model parameters and the attendant physical processes. The original synthetic stratigraphic section was produced with cyclical sea-level variations of 40 and 30 m with 2.4 and 10 Myr periods respectively. Sediment was also supplied cyclically, in 2.4 and 10 Myr cycles with amplitudes of 30 and 80 tons/100 kyr, respectively, varying from a mean of 232 tons/100 kyr. Parameter values were sampled to fit the model using a Markov chain Monte Carlo algorithm, resulting in a ±5 m (1σ) variation between the experimental output and the original. Sea level varied by ±7 m (1σ) within the posterior distribution of parameters. As a result, both the 10 Myr and 2.4 Myr sea-level cycles could be extracted from the original output. The variation in sediment supply was approximately ±38 tons/100 kyr (1σ) and, as a result, only the larger long-term supply variations could be accurately recovered in refitting the model. The variation in thermal, flexural and total subsidence across those parameter sets is less than ±10 m (1σ). The original section experienced 150 m of total subsidence at the depocentre. Our results demonstrate the distinct and interpretable imprint of sea level and subsidence on continental margin stratigraphy can be quantified. Moreover, we conclude that sea-level change produces a defined effect on the geometries of stratigraphic architecture, and that techniques applied for the purpose of delineating sea-level variation from continental margin strata have a well-founded conceptual basis.
AbstractThe response of the ocean overturning circulation to global warming remains controversial. Here, we integrate a multiproxy record from International Ocean Discovery Program Site U1490 in the western equatorial Pacific with published data from the Pacific, Southern and Indian Oceans to investigate the evolution of deep water circulation during the Miocene Climate Optimum (MCO) and Middle Miocene Climate Transition (MMCT). We find that the northward export of southern-sourced deep waters was closely tied to high-latitude climate and Antarctic ice cover variations. Global warming during the MCO drove a progressive decrease in carbonate ion concentration and density stratification, shifting the overturning from intermediate to deeper waters. In the western equatorial Pacific, carbonate dissolution was compensated by increased pelagic productivity, resulting in overall elevated carbonate accumulation rates after ~16 Ma. Stepwise global cooling and Antarctic glacial expansion during the MMCT promoted a gradual improvement in carbonate preservation and the initiation of a near-modern Pacific overturning circulation. We infer that changes in the latitudinal thermal gradient and in Southern Ocean zonal wind stress and upper ocean stratification drove radically different modes of deep water formation and overturning across the MCO and MMCT.
We produced a 10 Myr synthetic stratigraphic section using a forward stratigraphic model that generates marine deltaic stratigraphy over geological timescales. We recursively fit the model using a Bayesian inversion algorithm to test: (1) if it could be accurately reconstructed; (2) if the parameters used to create it could be recovered; and (3) the sensitivity of the model output to given model parameters and the attendant physical processes. The original synthetic stratigraphic section was produced with cyclical sea-level variations of 40 and 30 m with 2.4 and 10 Myr periods respectively. Sediment was also supplied cyclically, in 2.4 and 10 Myr cycles with amplitudes of 30 and 80 tons/100 kyr, respectively, varying from a mean of 232 tons/100 kyr. Parameter values were sampled to fit the model using a Markov chain Monte Carlo algorithm, resulting in a +/- 5 m (1 sigma) variation between the experimental output and the original. Sea level varied by +/- 7 m (1 sigma) within the posterior distribution of parameters. As a result, both the 10 Myr and 2.4 Myr sea-level cycles could be extracted from the original output. The variation in sediment supply was approximately +/- 38 tons/100 kyr (1 sigma) and, as a result, only the larger long-term supply variations could be accurately recovered in refitting the model. The variation in thermal, flexural and total subsidence across those parameter sets is less than +/- 10 m (1 sigma). The original section experienced 150 m of total subsidence at the depocentre. Our results demonstrate the distinct and interpretable imprint of sea level and subsidence on continental margin stratigraphy can be quantified. Moreover, we conclude that sea-level change produces a defined effect on the geometries of stratigraphic architecture, and that techniques applied for the purpose of delineating sea-level variation from continental margin strata have a well-founded conceptual basis. Modelledstratigraphy reconstructed using Bayesian inversion. The top panels show the reconstructedstratigraphy (panel a) and a wheeler diagram of this model output (panel b). Thethree other panels show the original and reconstructed values of: 1) flexure,thermal subsidence, and total subsidence (panel c); 2) sea-level change (paneld); and 3) sediment supply variations (panel e). The greater variability in theposterior distribution of sediment supply values relative to those for sealevel suggests that the development of passive continental margin stratigraphic architecture is particularlysensitive to sea-level variation.image
We evaluate the Cretaceous stratigraphy and carbon sequestration potential of the northern Baltimore Canyon Trough (NBCT) using >10,000 km of multi-channel seismic profiles integrated with geophysical logs, biostratigraphy, and lithology from 29 offshore wells. We identify and map six sequences resolved primarily at the stage level. Accommodation was dominated by thermal and non-thermal subsidence, though sequence boundaries correlate with regional and global sea-level changes, and the record is modified by igneous intrusion, active faulting, and changes in sediment supply and sources. Our stratigraphic maps illustrate a primary southern (central Appalachian) Early Cretaceous source that migrated northward during the Aptian and Albian. During the Cenomanian, sedimentation rates in the NBCT increased and depocenters shifted northward and landward. We show that deposition occurred in three phases: (1) earlier Cretaceous paleoenvironments were primarily terrestrial indicated by variable amplitude, chaotic seismic facies, serrated gamma logs, and heterolithic sandstones and mudstones with terrestrial microfossils; (2) the Albian to Cenomanian was dominated by deltaic paleoenvironments indicated by blocky, funnel-shaped, gamma-ray logs and clinoforms characterized by continuous high-amplitude seismic reflections with well-defined terminations; and (3) the Cenomanian and younger was marine shelf, inferred from mudstoneprone lithologies, peak gamma-ray values in well logs, and foraminiferal evidence. Long-term transgression and maximum water depths at the Cenomanian/Turonian boundary correlative with Ocean Anoxic Event 2 were followed by a regression and relative sea-level fall. We show that porous and permeable sandstones of three Aptian to Cenomanian highstand systems tracts are high-volume reservoirs for supercritical CO2 storage that are confined by overlying deep water mudstones.
Logging data are measurements of physical properties of the formation surrounding a borehole, acquired in situ after completion of coring (wireline logging) or during drilling (Logging-While-Drilling, LWD). The range of data (resistivity, gamma radiation, velocity, density, borehole images,…) in any hole depends on the scientific objectives and operational constraints.
Spatial analysis of discrepancies in sea‐level estimates derived from “backstripping” Mid‐Atlantic margin cores reveals a coherent signal that can be fit with a 10 3 km wavelength, 45 m amplitude sinusoid that moved across the margin at a rate and direction of motion generally opposite to that of the North American Plate. This signal we observe suggests topographical uplift occurred over much of the Mid‐Atlantic region since 35 Ma and may be superimposed upon a longer‐wavelength signal of Cenozoic subsidence associated with the subducted Farallon plate passing beneath the Mid‐Atlantic margin. Our statistical modeling of Mid‐Atlantic margin strata suggests that: (a) Cenozoic subsidence is likely to have occurred, but is very unlikely to have exceeded 100 m in magnitude; and (b) variations in ocean basin volume are likely to have contributed to 39 ± 24 m (1σ) of global‐mean geocentric sea‐level fall over the past 55 million years.
Logging data are measurements of physical properties of the formation surrounding a borehole, acquired in situ after completion of coring (wireline logging) or during drilling (Logging-While-Drilling, LWD). The range of data (resistivity, gamma radiation, velocity, density, borehole images,…) in any hole depends on the scientific objectives and operational constraints.
Heterogeneities within clinoforms, which can be in the form of variations in internal geometry and/or change in sediment distribution, may act as fluid flow barriers or conduits for hydrocarbon or freshwater reservoirs. These heterogeneities can lead to considerable uncertainty in estimating pore-fluid recovery factors by up to 35%. And yet, variations in sediment petrophysical characteristics within clinoforms have been poorly documented. Understanding the rock physics of clinoform heterogeneities along continental margins is a key to reducing the uncertainties in predicting the dynamics and the volume of recoverable pore fluids within these structures. The Miocene sedimentary record of the New Jersey continental margin is a prime candidate for studying continental-margin clinoform structures and the variation in their petrophysical properties. The margin has experienced a stable tectonic history, smooth and gradual thermal subsidence, and continuous sediment loading in the Miocene, resulting in deposition of well-developed siliciclastic clinoformal sequences. We use data from three IODP Expedition 313 boreholes and an encompassing high-resolution 3D multichannel seismic volume, collected in 2015 by the R/V M.G. Langseth on the New Jersey continental shelf, to predict shallow-marine sedimentological properties of the Miocene clinoforms at a significantly higher resolution (~5 m laterally) than previously achieved (~100s of m). We identify 76 system tracts and 22 sequences spanning ~8 m.y. of the Miocene. The results of our 3D stratigraphic analysis provide a detailed structural framework for analyses of the Miocene deposits to: 1) define the sedimentary structure in terms of stratal packages and 2) estimate the internal clinoform heterogeneity associated with phases of known mid-Cenozoic sea-level change. Our statistical analysis of the estimated elastic properties, including P-wave velocity (Vp), density and clay volume, reveals repeating spatial patterns in the internal rock physics properties of the Miocene clinoforms. We show that diagenesis and sediment compaction within the dipping parts of clinoforms cause a continuous increase of Vp in the seaward direction, with a magnitude that decreases from top to bottom. Our results also suggest that lithofacies change in clinoforms imposes a stronger influence on density, as lateral changes in lithofacies are more pronounced in sediment density than in Vp. In the Miocene sedimentary record, the transgressive system tracts show a seaward coarsening trend in grain size and a 3%-5% increase in density from clinoform topsets to bottomsets. Highstand and lowstand system tracts show a fining trend basinward, with a ~8% and 5% reduction in density, respectively. We further demonstrate that the identified trends can provide a standard model allowing incorporation of clinoforms in reservoir characterization techniques, such as model-based seismic inversion, and enable setting of guidelines on how the petrophysical properties change regionally in shallow-marine siliciclastic environments of continental margins.
Studies of ancient sea levels provide insights into the mechanisms and rates of sea level changes due to tectonic processes (e.g., ocean crust production) and climatic variations (e.g., insolation due to Earth's orbital changes and atmospheric CO2). Global mean sea level (GMSL) changes since the Middle Eocene (ca. 48 million years ago [Ma]) have been primarily driven by ice volume changes paced on astronomical timescales (2400, 1200, 95/125, 41, and 19/23 thousand years [kyr]), modulated by changes in atmospheric CO2. During peak warm intervals (e.g., Early Eocene Climatic Optimum 56-48 Ma and the early Late Cretaceous ca. 100-80 Ma), atmospheric CO2 was high and Earth was more than 5 degrees C warmer and mostly ice-free, contributing similar to 66 m of GMSL rise from ice alone. However, even in the warmest times (e.g., Early Eocene, ca 50 Ma), growth and decay of small ice sheets (<25 m sea level equivalent) likely drove sea level changes that inundated continents and controlled the record of shallow-water deposits. Ice sheets were confined to the interior of Antarctica prior to the Oligocene and first reached the Antarctic coast at 34 Ma, with the lowest sea levels -20 +/- 10 m relative to modern GMSL. Following a near ice-free Miocene Climatic Optimum (17-13.8 Ma), a permanent East Antarctic Ice Sheet (EAIS) developed in the Middle Miocene (ca. 13.8 Ma). During the Pliocene (4-3 Ma), CO2 was similar to 2020 CE (Common Era) and sea levels stood similar to 22 +/- 10 m above present, requiring significant loss of the Greenland Ice Sheet (similar to 7 m of sea level), West Antarctic Ice Sheet (similar to 5 m after isostatic compensation), and vulnerable portions of the EAIS. The small Northern Hemisphere ice sheets of the Eocene to Pliocene expanded into continental scale in the Quaternary (past 2.55 million years). Sea level reached its lowest point (similar to 130 m below present) during the Last Glacial Maximum (ca. 27-20 thousand years before 1950 [ka]), episodically rose during the deglaciation (ca. 20-11 ka) at rates that at times were in excess of 47 mm yr(-1) (vs. modern rates of 3.2 mm yr(-1)), and progressively slowed during the Early to Middle Holocene from ca. 11 ka until similar to 4 ka. During the Late Holocene (last 4.2 kyr, including the CE), GMSL only exhibited multi-centennial variability of +/- 0.1 m. The modern episode of GMSL rise began in the late nineteenth century, with most of the twentieth century rise attributable to global warming and ice melt. Under moderate emissions scenarios, GMSL is likely to rise 0.4-1.0 m in this century, with ancient analogs suggesting a longer term (centennial to millennial scale) equilibrium rise of similar to 10 m. Under higher emissions scenarios, twenty-first century GMSL will rise greater than 2 m, and in the long term, tens of meters cannot be excluded.
Both magmatic and tectonic processes contribute to the formation of volcanic continental margins. Such margins are thought to undergo extension across a narrow zone of lithospheric thinning (~100 km). New observations based on existing and reprocessed data from the Eastern North American Margin contradict this hypothesis. With ~64,000 km of 2‐D seismic data tied to 40 wells combined with published refraction, deep reflection, receiver function, and onshore drilling efforts, we quantified along‐strike variations in the distribution of rift structures, magmatism, crustal thickness, and early post‐rift sedimentation under the shelf of Baltimore Canyon Trough (BCT), Long Island Platform, and Georges Bank Basin (GBB). Results indicate that BCT is narrow (80–120 km) with a sharp basement hinge and few rift basins. The seaward dipping reflectors (SDR) there extend ~50 km seaward of the hinge line. In contrast, the GBB is wide (~200 km), has many syn‐rift structures, and the SDR there extend ~ 200 km seaward of the hinge line. Early post‐rift depocenters at the GBB coincide with thinner crust suggesting “uniform” thinning of the entire lithosphere. Models for the formation of volcanic margins do not explain the wide structure of the GBB. We argue that crustal thinning of the BCT was closely associated with late syn‐rift magmatism, whereas the broad thinning of the GBB segment predated magmatism. Correlation of these variations to crustal terranes of different compositions suggests that the inherited rheology determined the premagmatic response of the lithosphere to extension.
We evaluate Cretaceous depositional sequences on approximately 4400 km (∼2700 mi) of newly released multichannel seismic profiles and five wells on the continental shelf in the southern Baltimore Canyon trough and tie the data to three wells drilled onshore in the Maryland coastal plain. Seismic geometries coupled with facies and biostratigraphy from the wells are used to delineate mid-Cretaceous (Aptian–Turonian) depositional sequences and paleogeography. Beneath these sequences, 400–1000 m (1300–3300 ft) of Lower Cretaceous sedimentary rocks underlie the modern shelf. They thicken along strike to the southwest, implying a southern sediment source. Aptian to Cenomanian sediments were deposited in shelf to nearshore settings. A landward movement of the depocenter and a shift toward facies indicative of deeper paleodepths marks a 107-yr mid-Cretaceous transgression, within which we identify five sequences. A composite maximum flooding surface (MFS) within the uppermost of these retrogradational units is associated with the Cenomanian–Turonian boundary and ocean anoxic event 2. Shingled, lower Turonian seismic reflections prograde across the outer shelf, downlapping onto the composite MFS, and are truncated by a mid-Turonian sequence boundary. The Upper Cretaceous section thickens seaward and along strike to the northeast, implying a northern source and little Late Cretaceous accommodation beneath the modern shelf. Mid-Cretaceous strata offshore Maryland are likely sand-prone, considering their proximity to the correlative fluvial facies of the onshore Potomac Group. These potential reservoir sands are capped by regional confining units generated by 107-yr global mean sea-level flooding events and are excellent targets for supercritical carbon storage.