Forward modeling of stretching episodes and paleo heat flow of the Vøring margin, NE Atlantic

Wangen, Magnus; Fjeldskaar, Willy; Faleide, Jan Inge; Wilson, J. Tuzo; Zweigel, Janine; Austegard, Atle

doi:10.1016/j.jog.2007.07.002

Cited by 16 publications

(15 citation statements)

References 38 publications

(80 reference statements)

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“…To conserve mass, during the rifting phase, the lithosphere and sediment are both stretched by assuming a sediment column coupled with basement deformation, which is similar to the models of Theissen & Rüpke () and Wangen et al . ().…”

Section: Numerical Experimentsmentioning

confidence: 97%

Models of the rapid post‐rift subsidence in the eastern Qiongdongnan Basin, South China Sea: implications for the development of the deep thermal anomaly

et al. 2016

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The Qiongdongnan Basin is one of the largest Cenozoic rifted basins on the northern passive margin of the South China Sea. It is well known that since the Late Miocene, approximately 10 Ma after the end of the syn-rift phase, this basin has exhibited rapid thermal subsidence. However, detailed analysis reveals a two-stage anomalous subsidence feature of the syn-rift subsidence deficit and the wellknown rapid post-rift subsidence after 10.5 Ma. Heat-flow data show that heat flow in the central depression zone is 70-105 mW m À2, considerably higher than the heat flow (<70 mW m À2 ) on the northern shelf. In particular, there is a NE-trending high heat-flow zone of >85 mW m À2 in the eastern basin. We used a numerical model of coupled geothermal processes, lithosphere thinning and depositional processes to analyse the origin of the anomalous subsidence pattern. Numerical analysis of different cases shows that the stretching factor b s based on syn-rift sequences is less than the observed crustal stretching factor b c , and if the lithosphere is thinned with b c during the syn-rift phase (before 21 Ma), the present basement depth can be predicted fairly accurately. Further analysis does not support crustal thinning after 21 Ma, which indicates that the syn-rift subsidence is in deficit compared with the predicted subsidence with the crustal stretching factor b c . The observed high heat flow in the central depression zone is caused by the heating of magmatic injection equivalently at approximately 3-5 Ma, which affected the eastern basin more than the western basin, and the Neogene magmatism might be fed by the deep thermal anomaly. Our results suggest that the causes of the syn-rift subsidence deficit and rapid post-rift subsidence might be related. The syn-rift subsidence deficit might be caused by the dynamic support of the influx of warmer asthenosphere material and a small-scale thermal upwelling beneath the study area, which might have been persisting for about 10 Ma during the early post-rift phase, and the post-rift rapid subsidence might be the result of losing the dynamic support with the decaying or moving away of the deep thermal source, and the rapid cooling of the asthenosphere. We concluded that the excess post-rift subsidence occurs to compensate for the syn-rift subsidence deficit, and the deep thermal anomaly might have affected the eastern Qiongdongnan Basin since the Late Oligocene.

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Section: Numerical Experimentsmentioning

confidence: 97%

Models of the rapid post‐rift subsidence in the eastern Qiongdongnan Basin, South China Sea: implications for the development of the deep thermal anomaly

et al. 2016

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“…One way is to fix the upper boundary throughout the whole process (McKenzie, 1978;Rowley and Sahagian, 1986;Keen and Dehler, 1993), which is a simplification of the model; the other is to let the upper boundary subside with time according to isostatic compensation and the thermal evolution of lithosphere, reflecting the true process of basin formation (Wang et al, 1996;He and Wang, 2004;Wangen et al, 2008). We established the following two groups of model to study the influence of the fixed and moving upper boundary on the tectonic and thermal history.…”

Section: Effects Of the Upper Boundarymentioning

confidence: 99%

Discussion on Several Problems in Tectono‐Thermal Modeling of Rift Basins

Liu

2015

Chinese J of Geophysics

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Tectono-thermal modeling of rift basin is to calculate the thermal and subsidence history of a rift basin during its formation and evolution on a lithosphere scale, which links tectonic and thermal developments perfectly. However, most extension models have the following problems: assuming the lithosphere to be 125 km thick initially, ignoring heat convection in the asthenosphere, fixing the upper boundary and rarely including thermal effects of sediments when calculating rift flank uplifts. Some effects on the tectono-thermal modeling are discussed, including the initial crustal and lithosphere thicknesses, the convection of asthenosphere and the upper boundary of the model. We also calculate the differences of rift flank uplift between water and sediment loaded models.The tectono-thermal modeling is based on a two-dimensional non-instantaneous extension model using the finite-element method in the Lagrangian system. By solving the heat conduction equation, the thermal and tectonic subsidence histories of the basin are modeled simultaneously.The results are as follows: (1) Initial crustal and lithospheric thicknesses have great influence on tectonothermal modeling, especially on the tectonic subsidence. (2) Compared to the model ignoring heat convection in the asthenosphere, this model predicts slower tectonic subsidence and thermal decay rates, and significantly higher temperature from the lower crust to the bottom of the model. (3) The fixed or moving upper boundary during the modeling influences the calculated heat flow and tectonic subsidence in the thermal subsidence phase, and has remarkable effects on the temperature field. The effect increases with the increasing of stretching factor. (4) Rift flank uplift of the water-loaded model would disappear within millions of years while the uplift would be stable at a certain value for the sediment-loaded model.In cases that the initial crustal and lithospheric thicknesses are uncertain, the optimum initial thicknesses for crust and lithosphere can be determined when the calculated heat flow, Moho depth and lithospheric thickness fit observed values best. Pure heat conduction and pure heat convection in the asthenosphere are two limiting cases for extension models. Within the rheological boundary layer, heat is transferred by both conduction and convection. For strongly extensional areas, using the fixed upper boundary model would generate large calculation errors, especially in the temperature field. The thermal effect of sediment cannot be ignored when calculating the rift flank uplift.

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“…The rounded and shadowed boxes are denoting the computational results. The mantle and crustal properties [15,28] are listed in TABLE II. The entire model assumes a uniform heat flow distribution at the start of Late Triassic.…”

Section: B Forward Modeling Of Extension Subsidence and Heat Flowmentioning

confidence: 99%

“…However, thorough knowledge of local tectonic activities, depositional environments, the present-day temperature conditions and maturities are required for a closer examination of thermal history models. There are some studies have recently been done in Vøring basin and Vøring Plateau [8,23,28] but 3D detailed thermal evolution reconstruction in Halten Terrace is not yet available. The paleo heat flow in Halten Terrace is closely connected to the tectonic evolution on the margin because the deposition of a thick sedimentary layer may gives important contribution to the heat flow but on the other hand, the rapid deposition of low conductivity sediments may also depress the heat flow.…”

Section: Introductionmentioning

confidence: 99%

“…Besides, by the stretching and thinning of the crust, the radioactive heat production of the crust will also be influenced. [18] initiated the basin modeling in the North Sea and his model for lithospheric stretching has been widely used in a number of related studies [15,28]. This method has been also applied in our studies for the establishment of paleo heat flow simulation.…”

Section: Introductionmentioning

confidence: 99%

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Forward modeling of paleo heat flow: a case study of Kristin Field, Mid-Norwegian continental shelf

Unnithan

2009

Oceans 2009-Europe

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Temperature and paleo heat flow are critical of understanding of hydrocarbon plays in the Norwegian margin. The Kristin Field located on the Mid-Norwegian continental shelf is selected to construct a 3D thermal history model. The rift evolution of the Kristin Field and corresponding paleo heat flow have been modeled with forward modeling approach in our study. Based on the simulation of crustal thinning and tectonic subsidence, the average stretching factor 1.5 for crust and 2.5 for mantle were obtained in our study area. The crustal heat flow variations at different rift phases are presented by 1D extraction from the 3D model at well locations. The heat flow trend starts from 57 mW/m2 during the pre-rifting phase, increases to 83 mW/m2 at the end of Jurassic rifting phase and decays to 53 mW/m2 as a stationary state from 24 Ma to present. The modeled heat flow values are in agreement with published data in the vicinities of Halten Terrace. In particular, our study highlighted the thermal conditions for depth level below the reach of boreholes and provided useful information in determining source rock maturation and hydrocarbon generation history in the Halten Terrace area.

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Forward modeling of stretching episodes and paleo heat flow of the Vøring margin, NE Atlantic

Cited by 16 publications

References 38 publications

Models of the rapid post‐rift subsidence in the eastern Qiongdongnan Basin, South China Sea: implications for the development of the deep thermal anomaly

Models of the rapid post‐rift subsidence in the eastern Qiongdongnan Basin, South China Sea: implications for the development of the deep thermal anomaly

Discussion on Several Problems in Tectono‐Thermal Modeling of Rift Basins

Forward modeling of paleo heat flow: a case study of Kristin Field, Mid-Norwegian continental shelf

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