Conductive heat flow and nonlinear geothermal gradients in marine sediments—observations from Ocean Drilling Program boreholes

2015 ◽  
Vol 36 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Christian Stranne ◽  
Matt O’Regan
Keyword(s):  
Heat Flow ◽  
Marine Sediments ◽  
Conductive Heat ◽  
Ocean Drilling Program ◽  
Geothermal Gradients ◽  
Ocean Drilling ◽  
Conductive Heat Flow

scholarly journals Maastrichtian–Rupelian paleoclimates in the southwest Pacific – a critical re-evaluation of biomarker paleothermometry and dinoflagellate cyst paleoecology at Ocean Drilling Program Site 1172

2021 ◽  
Vol 17 (6) ◽  
pp. 2393-2425
Author(s):  
Peter K. Bijl ◽  
Joost Frieling ◽  
Margot J. Cramwinckel ◽  
Christine Boschman ◽  
Appy Sluijs ◽  
...  
Keyword(s):  
Marine Sediments ◽  
State Of The Art ◽  
Middle Eocene ◽  
Potential Temperature ◽  
Critical Evaluation ◽  
Marine Biodiversity ◽  
Early Eocene ◽  
Ocean Drilling Program ◽  
Ocean Drilling ◽  
Sw Pacific

Abstract. Sea surface temperature (SST) reconstructions based on isoprenoid glycerol dialkyl glycerol tetraether (isoGDGT) distributions from the Eocene southwest (SW) Pacific Ocean are unequivocally warmer than can be reconciled with state-of-the-art fully coupled climate models. However, the SST signal preserved in sedimentary archives can be affected by contributions of additional isoGDGT sources. Methods now exist to identify and possibly correct for overprinting effects on the isoGDGT distribution in marine sediments. Here, we use the current proxy insights to (re-)assess the reliability of the isoGDGT-based SST signal in 69 newly analyzed and 242 reanalyzed sediments at Ocean Drilling Program (ODP) Site 1172 (East Tasman Plateau, Australia) following state-of-the-art chromatographic techniques. We compare our results with paleoenvironmental and paleoclimatologic reconstructions based on dinoflagellate cysts. The resulting ∼ 130 kyr resolution Maastrichtian–Oligocene SST record based on the TetraEther indeX of tetraethers with 86 carbon atoms (TEX86) confirms previous conclusions of anomalous warmth in the early Eocene SW Pacific and remarkably cool conditions during the mid-Paleocene. Dinocyst diversity and assemblages show a strong response to the local SST evolution, supporting the robustness of the TEX86 record. Soil-derived branched GDGTs stored in the same sediments are used to reconstruct mean annual air temperature (MAAT) of the nearby land using the Methylation index of Branched Tetraethers with 5-methyl bonds (MBT'5me) proxy. MAAT is consistently lower than SST during the early Eocene, independent of the calibration chosen. General trends in SST and MAAT are similar, except for (1) an enigmatic absence of MAAT rise during the Paleocene–Eocene Thermal Maximum and Middle Eocene Climatic Optimum, and (2) a subdued middle–late Eocene MAAT cooling relative to SST. Both dinocysts and GDGT signals suggest a mid-shelf depositional environment with strong river runoff during the Paleocene–early Eocene progressively becoming more marine thereafter. This trend reflects gradual subsidence and more pronounced wet/dry seasons in the northward-drifting Australian hinterland, which may also explain the subdued middle Eocene MAAT cooling relative to that of SST. The overall correlation between dinocyst assemblages, marine biodiversity and SST changes suggests that temperature exerted a strong influence on the surface-water ecosystem. Finally, we find support for a potential temperature control on compositional changes of branched glycerol monoalkyl glycerol tetraethers (brGMGTs) in marine sediments. It is encouraging that a critical evaluation of the GDGT signals confirms that most of the generated data are reliable. However, this also implies that the high TEX86-based SSTs for the Eocene SW Pacific and the systematic offset between absolute TEX86-based SST and MBT'5me-based MAAT estimates remain without definitive explanation.

Thermal metamaterials for radiative plus conductive heat flow control

2020 ◽  
Vol 116 (19) ◽  
pp. 191902
Author(s):  
Ercan M. Dede ◽  
Ziqi Yu ◽  
Paul Schmalenberg ◽  
Hideo Iizuka
Keyword(s):  
Heat Flow ◽  
Flow Control ◽  
Conductive Heat ◽  
Conductive Heat Flow

Experimental Analysis of Thermal and Electric Transport Characteristics of Nano-Gaps

2011 ◽  
Author(s):  
Kohei Ito ◽  
Tomoaki Hagio ◽  
Akira Matsuo ◽  
Yasushi Iwaisako ◽  
Osamu Nakabeppu
Keyword(s):  
Heat Flow ◽  
Low Temperature ◽  
High Performance ◽  
Theoretical Study ◽  
Tunneling Current ◽  
Conductive Heat ◽  
Electric Transport ◽  
Probe Diameter ◽  
Thermoelectric Voltage ◽  
Conductive Heat Flow

We conducted an experiment to demonstrate the thermoelectric nano-gap, which is recently expected to own high performance, in principle, because it does not have conductive heat flow between the high and low temperature region. In this study, the thermoelectric nano-gap is realized with a pair of probe and substrate where they are finely positioned. A temperature difference of ca. 10 K is imposed to the nano-gap under vacuum circumstances. A representative thermoelectric voltage, tunneling-current and gap were 250 μV, 0.3 nA and 50 nm. The obtained voltage and current, with assuming an effective probe-diameter of 10 nm, roughly agreed to a theoretical study (G. Despesse and T. Jager, J. Appl. Phys., Vol.96, p.5026-, 2004). However, the obtained gap was 25 times larger than that from the theoretical study.

Shape factors for conductive heat flow

AIChE Journal ◽  
1958 ◽  
Vol 4 (3) ◽  
pp. 330-331 ◽  
Author(s):  
Julian C. Smith ◽  
John E. Lind ◽  
David S. Lermond
Keyword(s):  
Heat Flow ◽  
Conductive Heat ◽  
Shape Factors ◽  
Conductive Heat Flow

Natural convection in a corrugated slot

2017 ◽  
Vol 815 ◽  
pp. 537-569 ◽  
Author(s):  
Arman Abtahi ◽  
J. M. Floryan
Keyword(s):  
Natural Convection ◽  
Heat Flow ◽  
Convective Heat ◽  
Phase Difference ◽  
Conductive Heat ◽  
Heat Transfer Augmentation ◽  
Conductive Heat Flow ◽  
Secondary Motion ◽  
Prandtl Numbers

Analysis of natural convection in a horizontal slot formed by two corrugated isothermal plates has been carried out. The analysis is limited to subcritical Rayleigh numbers$Ra$where no secondary motion takes place in the absence of corrugations. The corrugations have a sinusoidal form characterized by the wavenumber, the upper and lower amplitudes and the phase difference. The most intense convection occurs for corrugation wavelengths comparable to the slot height; it increases proportionally to$Ra$and proportionally to the corrugation height. Placement of corrugations on both plates may either significantly increase or decrease the convection depending on the phase difference between the upper and lower corrugations, with the strongest convection found for corrugations being in phase, i.e. a ‘wavy’ slot, and the weakest for corrugations being out of phase, i.e. a ‘converging–diverging’ slot. It is shown that the shear forces would always contribute to the corrugation build-up if erosion was allowed, while the role of pressure forces depends on the location of the corrugations as well as on the corrugation height and wavenumber, and the Rayleigh number. Placing corrugations on both plates results in the formation of a moment which attempts to change the relative position of the plates. There are two limiting positions, i.e. the ‘wavy’ slot and the ‘converging–diverging’ slot, with the latter being unstable. The system would end up in the ‘wavy’ slot configuration if relative movement of the two plates was allowed. The presence of corrugations affects the conductive heat flow and creates a convective heat flow. The conductive heat flow increases with the corrugation height as well as with the corrugation wavenumber; it is largest for short-wavelength corrugations. The convective heat flow is relevant only for wavenumbers of$O(1)$, it increases proportionally to$Ra^{3}$and proportionally to the second power of the corrugation height. Convection is qualitatively similar for all Prandtl numbers$Pr$, with its intensity increasing for smaller$Pr$and with the heat transfer augmentation increasing for larger$Pr$.

scholarly journals Heat flow from the Earth interior as indicator of deep processes

Georesursy ◽  
2018 ◽  
Vol 20 (4) ◽  
pp. 366-376 ◽  
Author(s):  
B. Polyak ◽  
M. Khutorskoy
Keyword(s):  
Heat Flow ◽  
Hydrothermal Activity ◽  
Conductive Heat ◽  
Radiogenic Heat ◽  
The Earth ◽  
Open Discharge ◽  
Conductive Heat Flow ◽  
Different Depths ◽  
Tectonic Movements ◽  
Energy Aspects

The energy aspects of the problem of intraterrestrial heat transfer in various forms are discussed. Endogenous causes of conductive heat flow dispersion − radiogenic heat generation, tectonic movements and magmatism (volcanism), including its latent and open discharge in the form of volcanic and hydrothermal activity are considered. The geological ordering of the heat flow in the continental crust is related to convective discharge of the heat and mass flux from the mantle, marked by the isotopic composition of helium in freely circulating underground fluids. The combined transport of heat and helium, as well as the correlation of He isotopic compositions in volcanic and hydrothermal gases and Sr compositions in young lavas, testify to the silicate nature of the heat and mass flow emanating from the mantle reservoirs of different depths.

Sign in / Sign up

Export Citation Format

Share Document