Sediment Thickness Map Research Articles

WITHDRAWN: Global CO2 Storage Potential of Self‐Sealing Marine Sedimentary Strata

AbstractInjection of CO2 below the seafloor into sedimentary strata where pressures and temperatures would trap the CO2 through “self‐sealing” gravitational and hydrate‐formation mechanisms has received little interest after analyses of a selection of deep‐sea sediment cores suggested that such storage would not likely be feasible. Attention with respect to offshore CO2 storage has since shifted to the possibility of injecting CO2 into sub‐seafloor basalt layers embedded within impermeable strata. Here we re‐examine the storage potential of self‐sealing marine sedimentary strata using a more comprehensive, global dataset of deep‐sea sediment cores, heat flow measurements, bathymetry, and sediment thickness maps. In contrast to previous reports, we find the CO2 storage potential of these strata to be abundant. We map out the worldwide distribution and thicknesses of self‐sealing marine sedimentary strata, which we estimate to have a total bulk sediment volume of 63 million cubic kilometers. Of this, roughly 1.3–2.7% may prove suitable for CO2 storage. This storage is unevenly distributed where it lies within the Exclusive Economic Zones (EEZ) of the world's largest CO2 emitting economies. The United States and India respectively release 16% and 62% of their annual CO2 emissions (or 1 Bt/y and 800 Mt/y) within 500 km of self‐sealing strata located in their EEZs, while only 6% of the annual emissions from China and the European Union (or 330 Mt/y and 250 Mt/y, respectively) occur within this distance.

FAULT CONTROLS ON SEDIMENT DISTRIBUTION PATTERNS, LIMÓN BASIN, COSTA RICA

The Limón back‐arc basin on the Caribbean Seaboard of Costa Rica is an excellent area in which to study the influence of fault activity on patterns of sediment dispersal. The basin can be divided into northern and southern sub‐basins which are characterized by different structural histories. Whereas the North Limón Basin is dominated by extension, the South Limón Basin has been deformed by northeastward directed compression. Data from a grid of seismic lines in the offshore parts of these two sub‐basins allowed us to map the basin‐fill architecture and the key tectonic elements. Sediment thickness maps were used to infer the sediment distribution during the Middle Miocene, Late Miocene, Pliocene and Quaternary.The results of this study show that the extensional North Limón Basin has the characteristics of a passive continental margin. A wide and structurally homogeneous depocentre developed in relative tectonic quiescence. Tectonic activity increased in Plio‐Pleistocene times and pronounced normal faulting led to the formation of structurally‐controlled depocentres. The configuration in the South Limón Basin is different, since compressional tectonics created a heterogeneous pattern of accommodation space and sediment thickness. In this region, a number of small depocentres have been active since the Middle Miocene and their location changed continuously through time. These changes are most obvious in the Plio‐Pleistocene, where a succession of piggy‐back basins evolved in response to offshore activity on the Limón fold‐and‐thrust belt. Today, ongoing thrust tectonics causes topographic breaks at the sea‐floor of the South Limón Basin. These morphological features control the position of recent submarine channels.The data and interpretations presented here document the influence of fault activity on depositional patterns in a sedimentary basin. This study shows that tectonically controlled depocentres can be highly variable in space and time.

Investigation of earthquakes' geo-surroundings in the Pannonian Basin by using GIS tools

The mechanism of earthquake occurrence in the Pannonian Basin is not clear in most cases (in other words, it is often not possible to find a relationship between the location of epicenters and the elements of the maps of recent tectonic movements), hence a GIS has been created in order to clarify the origin of these events. The special seismological GIS includes all relevant information (maps and joint database) concerned with earthquakes covering the whole territory of Hungary. GIS contains the following maps: special macro- and microseismic epicenters and their parameters; different active tectonic fault maps; digital terrain model of the recent relief; digital terrain models of different geological basements; appropriate geophysical anomaly maps; Quaternary sediment thickness; recent rivers, water streams and settlements. GIS enables us to carry out special operations between different layers by applying its tools in order to reveal the recent tectonic movements and to throw light upon the generation of possible earthquake occurrences. Results of the present investigation in GIS revealed that significant relation exists between the earthquake foci and recent tectonic lines. Some foci, however, can not be related to fracture lines. One part of earthquakes showed agreement with Pre-Tertiary basement areas of considerable slope, with the recent tectonic elements of Geomorphological maps and with the piedmonts of the North Hungarian Range. Some traces of recent movements have been found with the help of the multiplication map of Quaternary sediment thickness map and Recent relief (Digital Elevation Model).

Evidence for strong sediment redistribution by bottom currents along the southeast Indian ridge

Understanding whether vigorous bottom currents redistribute biogenic components coming from the surface water is critical to evaluating the results from paleoenvironmental reconstructions based on sediment accumulation rates in the Southern Ocean. A large contourite drift along the southern flank of the Southeast Indian Ridge (SEIR) is recognized in published sediment thickness maps. We use the 230 Th method to estimate the contribution of advected sediments to the bulk sediment and rare-earth elements (REE) and trace-element compositions to determine the possible differences in sedimentary origin of the transported material. Magnetic susceptibility and “focusing factor” distributions suggest that (a) accumulation and sediment redistribution on the contourite drift have occurred throughout the last 40 ka, (b) the lateral transport of biogenous and detrital material represents 50–90% of the input at the foot of the SEIR, and (c) transport was even higher during glacial periods. Both REE profiles and trace-element ratios (La n /Tb n and Th/Sc) reveal that during the last glacial period, the terrigenous particles were mainly of volcanogenic origin, i.e., from the Crozet and Kerguelen slopes. The more significant contribution from the volcanic sources during the last glacial maximum is consistent with the action of the Antarctic Circumpolar Current-Circumpolar Deep Water (ACC-CDW). In addition, the formation of this tongue would be strongly linked to the long-term interactions between the Antarctic Bottom Water (AABW) and the ACC-CDW.

Relationship of Geological and Geothermal Field Properties; Midcontinent Area, USA, an Example

Quantitative approaches to data analysis have become important in basin modeling and mineral-resource estimation in the last decade. The interrelation of geological, geophysical, geochemical, and geohydrological variables is important in adjusting a model to a real-world situation. Revealing the interdependences of variables can contribute in understanding the processes interacting in sedimentary basins. It is simple to compare spatial data of the same type but more difficult if different properties are involved. Statistical techniques can be used to ascertain the relations of standardized spatial data. In this example, structural configuration on five different stratigraphic horizons, one total sediment thickness map, and four maps of geothermal information were compared. The structural maps were highly related because all had undergone about the same deformation with differing degrees of intensity. The temperature gradients (1) derived from borehole logging measurements under equilibrium conditions with the surrounding rock and (2) derived from unequilibrated bottomhole temperatures (BHT) are mainly independent of each other. This was expected and confirmed for the two temperature maps at 1000 ft which were constructed using both types of gradient values. Thus, it is evident that the use of BHT without correction to equilibrium conditions does not reflect the geothermal regime of themore » area. Nevertheless, it seemed useful to determine to what degree unequilibrated temperatures could reflect relationships to the geological conditions. Comparing all maps of geothermal information versus the structural and the sediment thickness maps it was determined that all correlations are moderately negative or slightly positive. These results are clearly shown by the cluster analysis and the principal components and support the assumption that the temperatures within the sediment are related closely to the lithological properties (rock conductivity) of the stratigraphic units.« less

Relationship of geological and geothermal field properties: Midcontinent area, USA, an example

Quantitative approaches to data analysis in the last decade have become important in basin modeling and mineral-resource estimation. The interrelation of geological, geophysical, geochemical, and geohydrological variables is important in adjusting a model to a real-world situation. Revealing the interdependences of variables can contribute in understanding the processes interacting in sedimentary basins. It is reasonably simple to compare spatial data of the same type but more difficult if different properties are involved. Statistical techniques, such as cluster analysis or principal components analysis, or some algebraic approaches can be used to ascertain the relations of standardized spatial data. In this example, structural configuration on five different stratigraphic horizons, one total sediment thickness map, and four maps of geothermal data were copared. As expected, the structural maps are highly related because all had undergone about the same deformation with differing degrees of intensity. The temperature gradients derived (1) from shallow borehole logging measurements under equilibrium conditions with the surrounding rock, and (2) from non-equilibrium bottom-hole temperatures (BHT) from deeper depths are mainly independent of each other. This was expected and confirmed also for the two temperature maps at 1000 ft which were constructed using both types of gradient values. Thus, it is evident that the use of a 2-point (BHT and surface temperature) straightline calculation of a mean temperature gradient gives different information about the geothermal regime than using gradients from temperatures logged under equilibrium conditions. Nevertheless, it is useful to determine to what a degree the larger dataset of nonequilibrium temperatures could reflect quantitative relationships to geologic conditions. Comparing all maps of geothermal information vs. the structural and the sediment thickness maps, it was determined that all correlations are moderately negative or slightly positive. These results are clearly shown by the cluster analysis and the principal components. Considering a close relationship between temperature and thermal conductivity of the sediments as observed for most of the Midcontinent area and relatively homogeneous heat-flow density conditions for the study area these results support the following assumptions: (1) undifferentiated geothermal gradients, computed from temperatures of different depth intervals and differing sediment properties, cannot contribute to an improved understanding of the temperature structure and its controls within the sedimentary cover, and (2) the quantitative approach of revealing such relations needs refined datasets of temperature information valid for the different depth levels or stratigraphic units.

Seismic, Side-Scan Survey, Diving, and Coring Data Analyzed by a Macintosh IITM Computer and Inexpensive Software Provide Answers to a Possible Offshore Extension of Landslides at Palos Verdes Peninsula, California: ABSTRACT

A Macintosh II{sup TM} computer and commercially available software were used to analyze and depict the topography, construct an isopach sediment thickness map, plot core positions, and locate the geology of an offshore area facing an active landslide on the southern side of Palos Verdes Peninsula California. Profile data from side scan sonar, 3.5 kHz, and Boomer subbottom, high-resolution seismic, diving, echo sounder traverses, and cores - all controlled with a mini Ranger II navigation system - were placed in MacGridzo{sup TM} and WingZ{sup TM} software programs. The computer-plotted data from seven sources were used to construct maps with overlays for evaluating the possibility of a shoreside landslide extending offshore. The poster session describes the offshore survey system and demonstrates the development of the computer data base, its placement into the MacGridzo{sup TM} gridding program, and transfer of gridded navigational locations to the WingZ{sup TM} data base and graphics program. Data will be manipulated to show how sea-floor features are enhanced and how isopach data were used to interpret the possibility of landslide displacement and Holocene sea level rise. The software permits rapid assessment of data using computerized overlays and a simple, inexpensive means of constructing and evaluating information inmore » map form and the preparation of final written reports. This system could be useful in many other areas where seismic profiles, precision navigational locations, soundings, diver observations, and core provide a great volume of information that must be compared on regional plots to develop of field maps for geological evaluation and reports.« less