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- Volume 32, Issue 5, 2020
Basin Research - Volume 32, Issue 5, 2020
Volume 32, Issue 5, 2020
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Flexural deformation controls on Late Quaternary sediment dispersal in the Garo‐Rajmahal Gap, NW Bengal Basin
[AbstractSubsurface deformation is a driver for river path selection when deformation rates become comparable to the autogenic mobility rate of rivers. Here we combine geomorphology, soil and sediment facies analyses, and geophysical data of the Late Quaternary sediments of the central Garo‐Rajmahal Gap in Northwest Bengal to link subsurface deformation with surface processes. We show variable sedimentation characteristics, from slow rates (<0.8 mm/year) in the Tista megafan at the foot of the Himalaya to nondeposition at the exposed surface of the Barind Tract to the south, enabling the development of mature soils. Combined subsidence in the Tista fan and uplift of the Barind Tract are consistent with a N‐S flexural response of the Indian plate to loading of the Himalaya Mountains given a low value of elastic thickness (15–25 km). Provenance analysis based on bulk strontium concentration suggests a dispersal of sediment consistent with this flexural deformation—in particular the abandonment of the Barind Tract by a Pleistocene Brahmaputra River and the current extents of the Tista megafan lobes. Overall, these results highlight the control by deeply rooted deformation patterns on the routing of sediment by large rivers in foreland settings.
,Sketch view of the study area showing the warping of Pleistocene sediments. Provenance analysis show a dispersal of sediment consistent with flexural deformation—in particular the abandonment of the Barind Tract by a Pleistocene Brahmaputra River and the current extents of the Tista megafan lobes.
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On the importance of rock thermal conductivity and heat flow density in basin and petroleum system modelling
[AbstractBasin and petroleum systems are routinely modelled to provide qualitative and quantitative assessments of a hydrocarbon play. The importance of the rock thermal properties and heat flow density in thermal modelling the history of a basin are well‐known, but little attention is paid to assumptions of the thermal conductivity, present‐day heat flow density and thermal history of basins. Assumed values are often far from measured values when data are available to check parameters, and effective thermal conductivity models prescribed in many basin simulators require improvement. The reconstructed thermal history is often justified by a successful calibration to present‐day temperature and vitrinite reflectance data. However, a successful calibration does not guarantee that the reconstruction history is correct. In this paper, we describe the pitfalls in setting the thermal conductivity and heat flow density in basin models and the typical uncertainties in these parameters, and we estimate the consequences by means of a one‐dimensional model of the super‐deep Tyumen SG‐6 well area that benefits from large amounts of reliable input and calibration data. The results show that the entire approach to present‐day heat flow evaluations needs to be reassessed. Unreliable heat flow density data along with a lack of measurements of rock thermal properties of cores can undermine the quality of basin and petroleum system modelling.
,Essential error of widely used geometric mean mixing rule for rock thermal conductivity estimation inferred from experiments as one of pitfalls of basin modelling.
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Volumes & issues
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Volume 36 (2024)
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Volume 35 (2023)
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Volume 34 (2022)
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Volume 33 (2021)
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Volume 32 (2020)
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Volume 31 (2019)
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Volume 30 (2018)
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Volume 29 (2017)
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Volume 28 (2016)
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Volume 27 (2015)
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Volume 26 (2014)
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Volume 25 (2013)
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Volume 24 (2012)
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Volume 23 (2011)
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Volume 22 (2010)
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Volume 21 (2009)
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Volume 20 (2008)
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Volume 19 (2007)
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Volume 18 (2006)
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Volume 17 (2005)
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Volume 16 (2004)
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Volume 15 (2003)
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Volume 14 (2002)
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Volume 13 (2001)
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Volume 12 (2000)
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Volume 11 (1999)
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Volume 10 (1998)
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Volume 9 (1997)
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Volume 8 (1996)
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Volume 7 (1994)
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Volume 6 (1994)
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Volume 5 (1993)
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Volume 4 (1992)
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Volume 3 (1991)
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Volume 2 (1989)
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Volume 1 (1988)