Vitrinite reflectance distributions and thermal history of sediments: An end-member sensitivity analysis

1989 ◽  
Vol 21 (4) ◽  
pp. 463-481 ◽  
Author(s):  
J. Horkowitz ◽  
I. Lerche ◽  
J. Pantano
Keyword(s):  
Sensitivity Analysis ◽  
Thermal History ◽  
Vitrinite Reflectance ◽  
History Of

Past hot fluid flows in limestones detected by Δ47–(U-Pb) and not recorded by other geothermometers

Geology ◽  
2020 ◽  
Vol 48 (9) ◽  
pp. 851-856 ◽  
Author(s):  
Benjamin Brigaud ◽  
Magali Bonifacie ◽  
Maurice Pagel ◽  
Thomas Blaise ◽  
Damien Calmels ◽  
...  
Keyword(s):  
Fluid Inclusions ◽  
Thermal History ◽  
Vitrinite Reflectance ◽  
Fluid Flows ◽  
Aqueous Fluid ◽  
Rift System ◽  
History Of ◽  
Clumped Isotope ◽  
Two Stages ◽  
Rock Eval

Abstract Geothermometers are commonly used to reconstruct the diagenetic and thermal history of rocks. However, characterizing the timing, origin, and temperature of paleofluid flow remains challenging because it must be assessed indirectly through the analysis of microscopic cements that precipitate and fill intergranular spaces during fluid circulation. Here, we measure both the clumped isotope (Δ47) temperature and in situ U-Pb age of individual diagenetic calcite cements within a sedimentary section of the Paris Basin (France), whose thermal history has been previously inferred to be <60 °C. We show that cementation occurred during two stages associated with major events at the western European lithospheric scale: (1) the Bay of Biscay rifting (Late Jurassic–Early Cretaceous), and (2) north-south Pyrenean compression (Eocene) followed by east-west extension during the European Cenozoic rift system event (Oligocene). Related to both events, we report unexpectedly hot fluids, up to 110 °C, contrasting with the lower temperatures inferred from other geothermometers (e.g., fluid inclusions, clay minerals, apatite fission tracks, maturity of organic matter by Rock-Eval pyrolysis, or vitrinite reflectance). These high temperatures (>70 °C) have been measured for calcite cements containing single-phase aqueous fluid inclusions, challenging the commonly accepted assertion that the absence of nucleation of a vapor phase indicates crystallization at low temperature (∼<70 °C). We suggest that the kinetics of mineralization events prevented the recording of short-lived hot fluid flows by other geothermometers.

Subsidence and thermal history of Queen Charlotte Basin

1983 ◽  
Vol 20 (1) ◽  
pp. 135-159 ◽  
Author(s):  
C. J. Yorath ◽  
R. D. Hyndman
Keyword(s):  
Heat Flow ◽  
Thermal History ◽  
Vitrinite Reflectance ◽  
Surface Profile ◽  
Fault System ◽  
Model Calculations ◽  
Geological Evidence ◽  
Queen Charlotte Islands ◽  
Crustal Thinning ◽  
History Of

A tectonic model for the formation, subsidence, and thermal history of Queen Charlotte Basin is developed. Based upon regional geological and geophysical data, subsidence data from offshore wells in Hecate Strait and Queen Charlotte Sound, and thermal criteria derived from present heat flow and vitrinite reflectance information, Queen Charlotte Basin is seen to have resulted from two distinct mechanisms. (1) During a period of broad regional uplift, rifting and crustal extension occurred in Queen Charlotte Sound up to about 17 Ma ago and the Queen Charlotte Islands were displaced northwards toward their present position by transcurrent motion along the Louscoone Inlet – Sandspit fault system. The rifting generated a significant thermal anomaly and a restricted deep basin as a consequence of crustal thinning and subsequent thermal cooling. (2) Beginning about 6 Ma ago, oblique underthrusting commenced along the margin, resulting in flexural uplift of the western part of the Queen Charlotte Islands and companion subsidence in Hecate Strait and Queen Charlotte Sound. The underthrusting caused rapid cooling of the old rift basins. This phase of subsidence has continued at a decreasing rate until the present.The tectonically generated subsidence in the basin has been estimated by correcting the well data for sediment compaction, paleo water depth, and sediment loading effects. At the site of the Harlequin well in the Queen Charlotte Sound rift, with the termination of extension and associated volcanism, the basin was 1500–2000 m deep and contained little sediment. Model calculations show that this depth is consistent with the estimated extension of about 70 km and a resulting crustal thinning to 8–10 km.Models for the lithosphere flexure generated by underthrusting are constrained by the geological evidence for uplift and erosion of over 5 km of material from the western portion of the Queen Charlotte Islands and the exponentially slowing subsidence to a present regional basement depth of 2 km in Hecate Strait. An excellent fit to the pre-erosion surface profile onshore and pre-Skonun basement surface offshore is obtained with a model having underthrusting on a 30° thrust at a 10 mm year−1 orthogonal component of convergence. The flexure generated by underthrusting, which is particularly well documented in the Queen Charlotte region, appears to be a feature of most subduction zones.Vitrinite reflectance data, present heat flow estimates from the wells, and thermal modelling indicate that the heat flux in Queen Charlotte Basin was much higher in the past than at present, particularly in Queen Charlotte Sound. A model is proposed with high heat flow generated by rifting prior to 17 Ma ago, followed by cooling from the underthrust oceanic lithosphere.

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