Gravity and magnetic modelling along seismic reflection profiles across the East Shetland Platform (Northern North Sea, UK)

Iapetus Ocean serpentinites and Mesozoic intra-platform basins revealed by gravity and magnetic modelling across the Greater East Shetland Platform (Northern North Sea, UK)

One of the important results of the Japan Sea drilling by ODP is the detection of an opal-A/opal-CT transformation at all the drill sites. The transformation boundary is well recognized in physical property and downhole measurements as well as in lithologic descriptions. Because the boundary shows a marked change of density, the boundary appears in seismic reflection profiles as a BSR. The transformation of opal-A to opal-CT is closely correlated with temperature and age of host rock in the Japan Sea. We estimate and evaluate Japan Sea heat flow by using the opal-A/opal-CT bottom simulating reflector (BSR) observed in seismic reflection profiles. Then we estimated the age of host rock from available seismic profiles based on the assumption of constant sedimentation rate. Therefore, the temperatures at opal-A/opal-CT boundary were estimated from seismic profiles. The temperature data were converted to surface heat flow data by using the thermal conductivity data obtained by shipboard physical property measurements. The estimated BSR heat flow showed significant agreement with individual probe heat flow data. We confirmed the validity of BSR heat flow on a multichannel seismic profile. This method can provide large areal estimates of the surface heat flow. The opal-A/opal-CT BSR can contribute to defining the thermal structure of the Yamato Basin, Japan Sea.

The well-known uncertainties in subsurface velocity field definition call for the integration of all the available data, including vintage seismic profiles, which, despite typically being in raster or paper format, often contain velocities derived from stacking and associated interval velocities. This study aims to build a velocity model for the time-to-depth conversion of an interpreted seismic reflection profile by using the interval velocity reported on a vintage, paper-format seismic profile and contribute to improving the subsurface geological model of the Sicily Channel, Central Mediterranean. Spline interpolation is used for velocity model building of the shallower part (3.5 sec TWT) of the seismic profile CS89-01, derived from the stacking velocities of 31 Common Depth Point (CDP) gathers. This was followed by the Gaussian convolution operator and a data exclusion filter to improve the accuracy of the velocity model. The time-to-depth-converted seismic reflection profile is a regional cross-section that covers almost the entire Sicily Channel, crossing part of the northern margin of the African Plate, from Tunisia to eastern Sicily. This study provides a new subsurface velocity field that can be applied, or taken into account, to most parts of the Sicily Channel when structural and stratigraphic interpretations are carried out at specific sites and where uncertainties in subsurface geological model exist (e.g., in the present study, the volcanic bodies in the Pantelleria Graben and Lampedusa High).

The thick sequence of Quaternary sediments preserved within the northern North Sea contains important information about the glacial history, palaeo-oceanographic conditions and slope stability of this region during the last 2.6 million years. The interplay between glacial, fluvial and contouritic processes can be determined from seismic stratigraphic studies. Here, seismic horizon, attribute and geomorphological interpretations of an extensive 2D seismic dataset (∼100,000 km2) and two 3D seismic cubes (∼18,400 km2) are integrated with lithological data from eight exploration wells to map sandy sedimentary units. Mapping of seismic horizons and facies reveals that, in addition to prograding glacial sediments derived from the Norwegian mainland, the Quaternary succession includes wedge-shaped units with prograding internal clinoforms building out from the East Shetland Platform, relatively flat-lying units of acoustically stratified sediments within the central northern North Sea, and aggrading to prograding units with low-amplitude internal reflections on the continental slope. The lowermost unit of Quaternary sediment is interpreted as an ∼800 km3 earliest Pleistocene (∼2.6 Ma) turbidite-contourite deposit, in which turbidites derived from a fluvial delta building out from the East Shetland Platform transition seaward into aggrading to prograding sediments of the Shetland Drift. The wedge-shaped units are intercalated with glacigenic sediments in the central northern North Sea, showing that the East Shetland Platform was a major source area for the delivery of coarse-grained sediments during the Early Pleistocene (∼2.6–0.8 Ma). The distribution of units of aggrading to prograding geometries suggests that contourites continued to develop on the continental slope, including on the North Sea trough-mouth fan, throughout the Quaternary. These interpretations constrain a new model for the Quaternary evolution of the northern North Sea that reconciles the development of the eastern and western sides of this margin, and shows the importance of fluvial-deltaic and contouritic sedimentation during periods of reduced glacigenic sediment input. Our model also provides a high-resolution analogue for the sedimentary architectures and seismic facies that can be produced by the interplay of down-slope and along-slope processes on other continental margins.

Research Article| January 01, 1999 Synthetic seismic reflection profile through the Ivrea zone–Serie dei Laghi continental crustal section, northwestern Italy Ernest H. Rutter; Ernest H. Rutter 1Earth Sciences Department, University of Manchester, Manchester M13 9PL, United Kingdom Search for other works by this author on: GSW Google Scholar Jalal Khazanehdari; Jalal Khazanehdari 1Earth Sciences Department, University of Manchester, Manchester M13 9PL, United Kingdom Search for other works by this author on: GSW Google Scholar Katharine H. Brodie; Katharine H. Brodie 1Earth Sciences Department, University of Manchester, Manchester M13 9PL, United Kingdom Search for other works by this author on: GSW Google Scholar Derek J. Blundell; Derek J. Blundell 2Geology Department, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom Search for other works by this author on: GSW Google Scholar David A. Waltham David A. Waltham 2Geology Department, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom Search for other works by this author on: GSW Google Scholar Author and Article Information Ernest H. Rutter 1Earth Sciences Department, University of Manchester, Manchester M13 9PL, United Kingdom Jalal Khazanehdari 1Earth Sciences Department, University of Manchester, Manchester M13 9PL, United Kingdom Katharine H. Brodie 1Earth Sciences Department, University of Manchester, Manchester M13 9PL, United Kingdom Derek J. Blundell 2Geology Department, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom David A. Waltham 2Geology Department, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1999) 27 (1): 79–82. https://doi.org/10.1130/0091-7613(1999)027<0079:SSRPTT>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Ernest H. Rutter, Jalal Khazanehdari, Katharine H. Brodie, Derek J. Blundell, David A. Waltham; Synthetic seismic reflection profile through the Ivrea zone–Serie dei Laghi continental crustal section, northwestern Italy. Geology 1999;; 27 (1): 79–82. doi: https://doi.org/10.1130/0091-7613(1999)027<0079:SSRPTT>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract A geologic cross section, restored to its original horizontal orientation in Permian-Triassic time, has been constructed for the middle and lower continental crustal rocks of the Ivrea-Verbano zone and the adjacent Serie dei Laghi of northwestern Italy. Seismic P-wave velocities of a representative suite of rock samples were measured to high-pressure and high-temperature conditions. A synthetic seismic reflection profile, ∼76 km long and 30 km thick, was computed to compare what can be deduced from the seismic profile with what is known in much more detail from geologic mapping. Imaged features correspond closely to those seen on many present-day profiles, and the broad features of the tectonic evolution would be correctly interpreted, but important recumbent fold structures would be missed, and relationships between intrusive bodies and their country rocks would be unclear. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Multicomponent vertical seismic profiles for reservoir characterization, South Casper Creek field, Natrona County, Wyoming

&amp;lt;p&amp;gt;In the East Shetland Platform (ESP) during the Paleocene, thick third order sequences (0.5 &amp;amp;#8211; 3 Myrs) were deposited during overall shelf progradation into the central North Sea, resulting in shelf - basin floor depositional profiles being preserved from Danian to Ypresian times. We interpreted the depositional record east of Shetland using over 40 000 km&amp;amp;#178; of 3D seismic data and circa 100 wells with biostratigraphic and lithostratigraphic picks, drawing key comparisons between the geometries of individual sequences along strike. We constructed multiple chronostratigraphic charts and relative sea-level curves for the area, which will later be used to study uplift and the influence of emplacement of large igneous provinces on source-to-sink systems.Deposition during the Danian is marked by a switch from quiescent carbonate and chalk platforms to strongly progradational clastics at the onset of uplift in the hinterland. This results in the first third-order pulses of clastic input in the ESP and in the adjacent Viking Graben, which correspond to sediments of the Maureen (Upper Danian &amp;amp;#8211; Middle Selandian) and Lista Formations (Upper Selandian to Middle Thanetian). These systems are dominated by sediment gravity flows in channel-lobe complexes, and are separated by a top Selandian Unconformity. From Thanetian to early Ypresian, multiple fourth order cycles of relative sea-level change can be recognized in shelfal sequences dominated by normal and forced regression. These include a broad domain of forced regressive to normal regressive shelf-margin &amp;amp;#8211; scale clinoforms (Dornoch Formation &amp;amp;#8220;Highstand&amp;amp;#8221; &amp;amp;#8211; sequence D1) that are correlated to an Upper Thanetian Unconformity in the proximal platform and systems of channelized sediment transport in the basin. This is followed by a set of rapidly prograding, flat trajectory clinoforms with wave-dominated shoreline delta geometries and considerable deposition in inner shelf, prodelta lobes (D2 &amp;amp;#8211; D4). These systems are interdigitated with a larger shelf-margin &amp;amp;#8211; scale clinothem of seemingly coeval age in the southern ESP, closer to the Piper Shelf. In the central ESP, close to the Beryl Embayment, basement reactivation during the Paleocene created structural highs that controlled estuarine or lagoonal - like systems during the Dornoch - Beauly cycles, which ended after significant clinoform progradation beyond the ESP and into the Viking Graben, although the exact nature of these clinoforms (sequence D5) is still unknown. The final sequence B1 is marked by the progressive onlap advance towards the continent (including coastal plain aggradation and backstepping) and eventually complete transgression of the Dornoch-Beauly shelf, which helped preserve erosional landscapes developed during the Dornoch progradation and also the posterior tidal invasion of the shelf. In the south, transgressive deposits are almost 200 ms thick (150 &amp;amp;#8211; 200 m) in some seismic profiles, but in the northern ESP shelf often only a single reflector of this same age is identified (&amp;lt; 40 ms). This highlights the marked influence of both tectonic tilting/doming and differential sediment supply &amp;lt;em&amp;gt;versus&amp;lt;/em&amp;gt; accommodation rates along strike in the ESP, which are interpreted as a direct result of the activity of the Icelandic Plume in the continent.&amp;lt;/p&amp;gt;

A 2‐D gravity model, incorporating geophysical and geological data, is presented for a 110 km long transect across the northern Rhine Graben, coinciding with the 92 km long DEKORP 9‐N seismic reflection profile. The Upper Rhine Graben is marked by a prominent NNE‐striking negative anomaly of 30–40 mgal on Bouguer gravity maps of SW Germany. Surface geological contacts, borehole data and the seismic reflection profile provide boundary constraints during forward modelling.Short‐wavelength (5–10 km) gravity features can be correlated with geologic structures in the upper few km. At deeper levels, the model reflects the asymmetry visible in the seismic profile; a thicker, mostly transparent lower crust in the west and a thinner, reflective lower crust in the east. From west to east Moho depth changes from 31 to 26–28 km. The entire 40 mgal minimum can be accounted for by the 2–3 km of light sedimentary fdl in the graben, which masks the gravitational effects of the elevated Moho. The thickened lower crust in the west partly compensates for the mass deficit from the depressed Moho. A further compensating feature is a relatively low density contrast at the crust‐mantle boundary of 0.25 g cm‐3. The Variscan must displays heterogeneity along the profile which cuts at an angle across the strike of Variscan structures. The asymmetry of the integrated crustal model, both at the surface and at depth suggests an asymmetric mechanism of rift development.

Imaging the crustal structure beneath the eastern Tibetan Plateau and implications for the uplift of the Longmen Shan range

The Pliocene–Quaternary tectonic evolution of the Cilicia and Adana basins, eastern Mediterranean: Special reference to the development of the Kozan Fault zone

Summary It is very important to have good subsurface data in order to understand the nature and behaviour of thrust faults. Deep crustal seismic reflection profiling is the best technique currently available to make detailed subsurface studies of such important problems as the attitude and extent at depth of major faults, and hence deduce the mode of deformation and tectonic forces producing them. The Consortium for Continental Reflection Profiling (COCORP) is collecting large quantities of seismic reflection data from the deep crust and upper mantle in many parts of the U.S.A. Areas of major thrusting which have been profiled so far by COCORP include the Wind River Mountains in Wyoming and the Southern Appalachians of Georgia and Tennessee. Seismic profiles have been very successful in delineating a major thrust fault of moderate dip underlying the Wind River Mountains, thus demonstrating that compressional tectonics were dominant in their formation. In Georgia and Tennessee the seismic profiles demonstrate that the major tectonic feature of the Southern Appalachians is a relatively thin overthrust sheet, which may have moved at least 260 km. Deep crustal seismic reflection profiling thus appears to be an indispensable tool for the study of areas in which thrusting and nappe formation have occurred.

Well Log-Seismic Sequence Stratigraphy Analysis is a new technology that integrates high resolution biostratigraphic and paleobathymetric data and the characteristics of the well log signatures with seismic reflection profiles. This methodology permits the biostratigrapher, geologist and geophysicist to work together to subdivide a stratigraphic section into packages of sediments bounded by chronostratigraphically significant condensed sections and their associated maximum flooding surfaces and sequence boundaries using well logs and seismic profiles. Each sequence is subdivided into smaller lithogenetic (facies linked) units called systems tracts on the basis of characteristic well-log patterns. The systems tract boundaries, are identified on well logs, marked on two-way time logs or synthetic seismograms and correlated with corresponding systems tracts that have been independently identified on the seismic profiles using seismic-stratigraphic interpretation procedures (Vail and Wornardt, 1990). Faunal and floral abundance and diversity histograms provide critical information to make reproducible chronostratigraphic correlations (Huang and Wornardt, 1986; Shaffer, 1987; Wornardt, 1989; and Shaffer, 1990). The paleobathymetric interpretations permit the identification of rock types in relation to the depositional environment and systems tracts. The high resolution biostratigraphy is critical in integrated well log-seismic sequence stratigraphic analysis because it provides information for identifying fossil abundance and diversity peaks that are important for recognizing and correlating condensed sections and maximum flooding surfaces on well logs and seismic profiles. High resolution biostratigraphy and paleobathymetry data provides the additional data package that has heretofore been missing in seismic sequence stratigraphy. Added to the well log and seismic data set, they provide an integrated data package that permits the inexperienced person to use the concepts of seismic well log-sequence stratigraphy to develop expertise and confidence in its practice. In order to obtain consistently reliable results in well log-seismic sequence stratigraphy, a particular procedure must be fo lowed and specific data sets must be used.

The Late Quaternary sedimentary succession and sea-level changes in the Gulf of Ku&amp;#351;adas&amp;#305;, located in the Aegean Sea, have been comprehensively examined using high-resolution seismic reflection profiles and sediment cores collected by R/V TUBITAK Marmara in 2022. The seismic stratigraphy reveals four main depositional units, each bounded by distinct reflection surfaces that reflect significant sea-level fluctuations since the Last Glacial Maximum (LGM). Correlation of the seismic profiles with the 14C-dated sediment cores provides the robust chronology of seismic stratigraphic units, seismic boundaries, paleo wave-abraded platforms, and marine terraces. The depths of the paleoshorelines observed in the seismic profiles were compared with the global sea-level curve to more accurately determine the timing of sea-level changes in the gulf. The deepest wave-abraded platform observed in the seismic profiles is at a depth of -172 m. According to chronology of the depositional units in the seismics adjusted with 14C-datings from the cores, the deepest wave-abraded platform at -172 m in the seismic profile conforms with the sea-level lowstand (-135 m) at ca. 21.5 cal ka BP during the LGM based on the global sea-level curve. Such comparison reveals the subsidence of the submerged seafloor due to vertical displacement along active normal faults in the Gulf of Ku&amp;#351;adas&amp;#305; since the LGM. Subsequent sea-level rise triggered by post-glacial warming led to the deposition of transgressive units characterized by coastal onlaps and localized channel fills. Brief sea-level stillstands disrupted this transgressive phase at approximately 17 cal ka BP and 14.6 cal ka BP, forming younger wave-abraded platforms at -135 m and -112.5 m, respectively. The depths of these platforms, compared with the global sea-level curve, suggest ongoing subsidence at a slower rate, indicating a complex interplay between sea-level changes and tectonic activity in the Gulf. The subsidence is likely attributed to tectonic movements along the seafloor rather than hydrostatic loading.The acoustic reflection characteristics, together with the geometry and spatial extents of the seismic stratigraphic units, also provide important insights into the depositional processes during the changing sea-level. The most prominent depositional facies can be presented in the seismic profiles as two amalgamated deltaic sequences of the paleo-K&amp;#252;&amp;#231;&amp;#252;k Menderes River. Their depositional periods can be confidently deduced from the correlation of the seismic stratigraphic units with the chronostratigraphic units in the cores. The topset/foreset transitions of these deltaic sequences, located at depths of -37.5 m and -112.5 m in the seismic profiles, correspond to estimated ages of 9.3 cal ka BP and 14.6 cal ka BP, respectively.

We show that by using an advanced pre-stack depth imaging algorithm it is possible to retrieve meaningful and robust seismic images with sparse shot points, using only 3–4 source points per kilometer along a seismic profile. Our results encourage the use of 2D seismic reflection profiling as a reconnaissance tool for mineral exploration in areas with limited access for active seismic surveys. We used the seismic data acquired within the COGITO-MIN project comprising two approximately 6 km long seismic reflection profiles at the polymetallic Kylylahti massive sulfide mine site in eastern Finland. The 2D seismic data acquisition utilized both Vibroseis and dynamite sources with 20 m spacing and wireless receivers spaced every 10 m. For both source types, the recorded data show clear first breaks over all offsets and reflectors in the raw shot gathers. The Kylylahti area is characterized by folded and faulted, steeply dipping geological contacts and structures. We discuss post-stack and pre-stack data processing and compare time and depth imaging techniques in this geologically complex Precambrian hardrock area. The seismic reflection profiles show prominent reflectors at 4.5–8 km depth utilizing different migration routines. In the shallow subsurface, steep reflectors are imaged, and within and underneath the known Kylylahti ultramafic body reflectivity is prominent but discontinuous.

Variable post-Paleozoic deformation detected by seismic reflection profiling across the northwestern “prong” of New Madrid seismic zone