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Neumann, F, Negrete-Aranda R, Harris RN, Contreras J, Sciater JG, Gonzalez-Fernandez A.  2017.  Systematic heat flow measurements across the Wagner Basin, northern Gulf of California. Earth and Planetary Science Letters. 479:340-353.   10.1016/j.epsl.2017.09.037   AbstractWebsite

A primary control on the geodynamics of rifting is the thermal regime. To better understand the geodynamics of rifting in the northern Gulf of California we systematically measured heat-flow across the Wagner Basin, a tectonically active basin that lies near the southern terminus of the Cerro Prieto fault. The heat flow profile is 40 km long, has a nominal measurement spacing of similar to 1 km, and is collocated with a seismic reflection profile. Heat flow measurements were made with a 6.5-m violin-bow probe. Although heat flow data were collected in shallow water, where there are significant temporal variations in bottom water temperature, we use CTD data collected over many years to correct our measurements to yield accurate values of heat flow. After correction for bottom water temperature, the mean and standard deviation of heat flow across the western, central, and eastern parts of the basin are 220 +/- 60, 99 +/- 14, 889 +/- 419 mW m(-2), respectively. Corrections for sedimentation would increase measured heat flow across the central part of basin by 40 to 60%. We interpret the relatively high heat flow and large variability on the western and eastern flanks in terms of upward fluid flow at depth below the seafloor, whereas the lower and more consistent values across the central part of the basin are suggestive of conductive heat transfer. Moreover, heat flow across the central basin is consistent with gabbroic underplating at a depth of 15 km and suggests that continental rupture here has not gone to completion. (C) 2017 Elsevier B.V. All rights reserved.

Takeuchi, CS, Sclater JG, Grindlay NR, Madsen JA, Rommevaux-Jestin C.  2010.  Segment-scale and intrasegment lithospheric thickness and melt variations near the Andrew Bain megatransform fault and Marion hot spot: Southwest Indian Ridge, 25.5 degrees E-35 degrees E. Geochemistry Geophysics Geosystems. 11   10.1029/2010gc003054   AbstractWebsite

We analyze bathymetric, gravimetric, and magnetic data collected on cruise KN145L16 between 25.5 degrees E and 35 degrees E on the ultraslow spreading Southwest Indian Ridge, where the 750 km long Andrew Bain transform domain separates two accretionary segments to the northeast from a single segment to the southwest. Similar along-axis asymmetries in seafloor texture, rift valley curvature, magnetic anomaly amplitude, magnetization intensity, and mantle Bouguer anomaly (MBA) amplitude within all three segments suggest that a single mechanism may produce variable intrasegment lithospheric thickness and melt delivery. However, closer analysis reveals that a single mechanism is unlikely. In the northeast, MBA lows, shallow axial depths, and large abyssal hills indicate that the Marion hot spot enhances the melt supply to the segments. We argue that along-axis asthenospheric flow from the hot spot, dammed by major transform faults, produces the inferred asymmetries in lithospheric thickness and melt delivery. In the southwest, strong rift valley curvature and nonvolcanic seafloor near the Andrew Bain transform fault indicate very thick subaxial lithosphere at the end of the single segment. We suggest that cold lithosphere adjacent to the eastern end of the ridge axis cools and thickens the subaxial lithosphere, suppresses melt production, and focuses melt to the west. This limits the amount of melt emplaced at shallow levels near the transform fault. Our analysis suggests that the Andrew Bain divides a high melt supply region to the northeast from an intermediate to low melt supply region to the southwest. Thus, this transform fault represents not only a major topographic feature but also a major melt supply boundary on the Southwest Indian Ridge.

Peyve, AA, Skolotnev SG, Ligi M, Turko NN, Bonatti E, Kolodyazhnyi SY, Chamov NP, Tsukanov NV, Baramykov YE, Eskin AE, Grindlay N, Sclater JG, Brunelly D, Pertsev AN, Cipriani A, Bortoluzzi G, Mercuri R, Paganelli E, Muccini F, Takeuchi C, Zaffagnini F, Dobrolyubova KO.  2007.  Investigation of the Andrew Bain transform fault zone (African-Antarctic region). Doklady Earth Sciences. 416:991-994.   10.1134/S1028334X07070021   Abstract
Crosby, AG, McKenzie D, Sclater JG.  2006.  The relationship between depth, age and gravity in the oceans. Geophysical Journal International. 166:553-573.   10.1111/j.1365-246X.2006.03015.x   AbstractWebsite

We reassess the applicability of the thermal plate cooling model to the subsidence of the North Pacific, Atlantic and North Indian Ocean Basins. We use a new numerical plate model in which the thermophysical parameters of the lithosphere vary with temperature according to the results of laboratory experiments, and the ridge temperature structure is consistent with the thickness of the oceanic crust. We first attempt to exclude thickened crust from our data set, and then to exclude swells and downwellings by masking regions of the data that remains that have significant gravity anomalies when there exists a clear regional correlation between intermediate-wavelength gravity and topography. We find that the average variation of depth with age is consistent with conventional half-space models until about 90 Myr. Thereafter, the departure from the half-space cooling curve is more rapid than predicted using simple conductive plate cooling models. The depth-age curves in the Pacific and Atlantic show similar to 250 m of temporary shallowing between the ages of 90-130 Myr, a result consistent with the outcome of experiments on the initiation of small-scale boundary layer convection. The results do not change significantly if the estimated component of the gravity arising from plate cooling is subtracted prior to calculation of the correlation between gravity and topography. A 90-km-thick conductive plate is nevertheless a reasonable model for the average temperature structure of the oldest part of the Pacific ocean lithosphere. In the Pacific, the broad topographic undulations associated with the Line Island Swell, the Hawaiian Swell and surrounding basins have correlated gravity anomalies and an admittance of approximately 30 mGal km(-1) and are likely to result from convective circulation in the upper mantle. In the Northeast Atlantic, the intermediate-wavelength admittance over the Cape Verde swell is similar; in the Northwest Atlantic over the Bermuda Swell it is slightly larger but not as well constrained.

Sclater, JG, Grindlay NR, Madsen JA, Rommevaux-Jestin C.  2005.  Tectonic interpretation of the Andrew Bain transform fault: Southwest Indian Ocean. Geochemistry Geophysics Geosystems. 6   10.1029/2005gc000951   AbstractWebsite

[1] Between 25 degrees E and 35 degrees E, a suite of four transform faults, Du Toit, Andrew Bain, Marion, and Prince Edward, offsets the Southwest Indian Ridge (SWIR) left laterally 1230 km. The Andrew Bain, the largest, has a length of 750 km and a maximum transform domain width of 120 km. We show that, currently, the Nubia/ Somalia plate boundary intersects the SWIR east of the Prince Edward, placing the Andrew Bain on the Nubia/ Antarctica plate boundary. However, the overall trend of its transform domain lies 10 degrees clockwise of the predicted direction of motion for this boundary. We use four transform-parallel multibeam and magnetic anomaly profiles, together with relocated earthquakes and focal mechanism solutions, to characterize the morphology and tectonics of the Andrew Bain. Starting at the southwestern ridge-transform intersection, the relocated epicenters follow a 450-km-long, 20-km-wide, 6-km-deep western valley. They cross the transform domain within a series of deep overlapping basins bounded by steep inward dipping arcuate scarps. Eight strike-slip and three dip-slip focal mechanism solutions lie within these basins. The earthquakes can be traced to the northeastern ridge-transform intersection via a straight, 100-km-long, 10-km-wide, 4.5-km-deep eastern valley. A striking set of seismically inactive NE-SW trending en echelon ridges and valleys, lying to the south of the overlapping basins, dominates the eastern central section of the transform domain. We interpret the deep overlapping basins as two pull-apart features connected by a strike-slip basin that have created a relay zone similar to those observed on continental transforms. This transform relay zone connects three closely spaced overlapping transform faults in the southwest to a single transform fault in the northeast. The existence of the transform relay zone accounts for the difference between the observed and predicted trend of the Andrew Bain transform domain. We speculate that between 20 and 3.2 Ma, an oblique accretionary zone jumping successively northward created the en echelon ridges and valleys in the eastern central portion of the domain. The style of accretion changed to that of a transform relay zone, during a final northward jump, at 3.2 Ma.

Sclater, JG.  2004.  Variability of heat flux through the seafloor: discovery of hydrothermal circulation in the oceanic crust. Hydrogeology of the oceanic lithosphere. ( Davis EE, Ed.).:3-27., Cambridge: Cambridge University Press Abstract
Sclater, JG.  2003.  Earth science - Ins and outs on the ocean floor. Nature. 421:590-591.   10.1038/421590a   AbstractWebsite
Fisher, AT, Giambalvo E, Sclater J, Kastner M, Ransom B, Weinstein Y, Lonsdale P.  2001.  Heat flow, sediment and pore fluid chemistry, and hydrothermal circulation on the east flank of Alarcon Ridge, Gulf of California. Earth and Planetary Science Letters. 188:521-534.   10.1016/s0012-821x(01)00310-7   AbstractWebsite

New seismic, heat flow, sediment and pore fluid geochemistry data from the east flank of Alarcon Ridge. at the mouth of the Gulf of California, provide evidence for vigorous hydrothermal circulation within young oceanic crust formed at a moderate-rate spreading center. Data and samples were collected 9-20 km from the ridge axis to assess the hydrologic state of 0.30-0.65 Ma seafloor. Conductive heat now values are 15-55% of that input at the base of the lithosphere. Heat flow is highest near the center of a sediment-covered trough, and lowest along the trough margins, suggesting that trough-bounding faults and basement exposures may help to focus hydrothermal recharge. Sediment and pore fluid geochemistry data, in combination with reactive transport modeling. indicate that conditions within the shallow sediments are dominantly diffusive and reactive in two locations, but that bottom seawater recharges through the thin sediment layer with velocities on the order of 2-10 mm/yr at other sites. Seafloor heat now appears to be entirely conductive, which is consistent with the slow rate of seepage inferred from pore fluid observations and modeling. Fluid recharge through sediments requires that basement is underpressured relative to hydrostatic conditions. We interpret these observations and inferences to indicate vigorous fluid flow in basement. and secondary seepage through overlying sediments. The heat flow deficit along the 11-km Alarcon Basin transect averages 440 mW/m(2), equivalent to heat output of 5 MW per kilometer of spreading axis. This heat output is similar to the combined focused and diffusive heat output of a single basement outcrop on the east flank of Juan de Fuca Ridge. and suggests that sites of concentrated heat and fluid outflow may exist on the east flank of Alarcon Ridge. (C) 2001 Published by Elsevier Science B.V.

Sclater, JG.  2001.  Heat flow under the oceans. Plate tectonics: an insider's history of the modern theory of the Earth. ( Oreskes N, LeGrand HE, Eds.).:128-147., Boulder, Colo.: Westview Press Abstract

Collects eighteen essays on the development of the theory of plate tectonics, covering key concepts, terminology, and the contributions of the scientists who helped develop the model that is today widely accepted in the field.

Grindlay, NR, Madsen JA, Rommevaux-Jestin C, Sclater J.  1998.  A different pattern of ridge segmentation and mantle Bouguer gravity anomalies along the ultra-slow spreading Southwest Indian Ridge (15 degrees 30 ' E to 25 degrees E). Earth and Planetary Science Letters. 161:243-253.   10.1016/s0012-821x(98)00154-x   AbstractWebsite

The results of a recent bathymetric and geophysical investigation of a similar to 650 km-long portion of the very slowly opening (16 mm/yr full rate) Southwest Indian Ridge (SWIR) between 15 degrees 30'E and 25 degrees E are presented. Bathymetry and mantle Bouguer gravity anomalies (MBA), caused by variations in crustal thickness and/or crustal and upper mantle densities, show different characteristics from those observed at faster spreading centers like the Mid-Atlantic Ridge (MAR) (20-30 mm/yr full rate). With the exception of the Du Toit Transform, none of the ridge-axis discontinuities have offsets greater than 10 km and few of the discontinuities have clearly defined off-axis traces. The MBA patterns associated with individual segments are much more complex than the simple circular bull's eyes lows reported along the MAR. While the short wavelength ridge segment length is comparable to that of the MAR, there is little correlation with MBA amplitude and segment length and axial relief. Furthermore, an eastward propagating magma source and an similar to 84 km-long zone of oblique spreading appears to define a fundamental boundary along the SWIR between two 250-300 km-long sections characterized by distinctly different axial morphology and gravity signatures. We interpret these results to indicate a long-wavelength segmentation pattern of the underlying upwelling mantle. Melt separates from the upwelling mantle at the base of the lithosphere and is channeled to the surface along dikes. Fissure eruptions within the rift valley build linear ridges defining a short-wavelength spatial pattern of ridge segmentation that is not directly related to the segmentation pattern of the upwelling mantle. Our results and interpretation are quite different than that predicted by extending current models of the faster spreading MAR to these ultra-slow spreading rates. (C) 1998 Elsevier Science B.V. All rights reserved.

Muller, RD, Roest WR, Royer JY, Gahagan LM, Sclater JG.  1997.  Digital isochrons of the world's ocean floor. Journal of Geophysical Research-Solid Earth. 102:3211-3214.   10.1029/96jb01781   AbstractWebsite

We have created a digital age grid of the ocean poor with a grid node interval of 6 are min using a self-consistent set of global isochrons and associated plate reconstruction poles. The age at each grid node was determined by linear interpolation between adjacent isochrons in the direction of spreading. Ages for ocean floor between the oldest identified magnetic anomalies and continental crust were interpolated by estimating the ages of passive continental margin segments from geological data and published plate models. We have constructed an age grid with error estimates for each grid cell as a function of (1) the error of ocean floor ages identified from magnetic anomalies along ship tracks and the age of the corresponding grid cells in our age grid, (2) the distance of a given grid cell to the nearest magnetic anomaly identification, and (3) the gradient of the age grid: i.e., larger errors are associated with high age gradients at fracture zones or other age discontinuities. Future applications of this digital grid include studies of the thermal and elastic structure of the lithosphere, the heat loss of the Earth, ridge-push forces through time, asymmetry of spreading, and providing constraints for seismic tomography and mantle convection models.

Nagihara, S, Lister CRB, Sclater JG.  1996.  Reheating of old oceanic lithosphere: Deductions from observations. Earth and Planetary Science Letters. 139:91-104.   10.1016/0012-821x(96)00010-6   AbstractWebsite

Deep, wide oceanic basins are the only regions of old seafloor where depth is truly representative of thermal isostasy. When the depths of these basins are corrected for the effect of sediment accumulation, and variation in crustal thickness, the principal non-thermal factors have been eliminated. We collect the most precise and reliable values of heat flow for the same basins, from multi-penetration measurements with in situ thermal conductivity, or deep sea drilling thermal gradients backed up by surface surveys, The 9 data points that result from this selection process have been plotted on a depth versus heat flow graph and compared to published thermal models of lithosphere. When considered without regard to age, all the points fall al greater depths than predicted by the 'plate' models with constant temperature lower boundaries, and remarkably close to boundary-layer cooling with parameters determined from the pre-80 Ma depth and heat flow history of the ocean floor. They are differentiated by their heat flows not much by their depths and the order they plot in along the heat flow axis is random with respect to crustal age. Modeling of discrete reheating events shows that near boundary layer conditions are re-established after about 40 Myr, but corresponding to a younger-than-real age. The data therefore favor discrete reheating events rather than a continuously hot basal boundary, as implicitly assumed by the plate model. Lithospheric reheating appears to start only on ocean floor > 100 Ma. The data alone cannot discriminate between a few discrete reheating events due to convective peel-off at the base of the lithosphere or one or more catastrophic events. However, the distribution of points from the Blake-Bahama basin is more consistent with distal reheating associated with the Bermuda hotspot than local convective peel-off.

Nagihara, S, Sclater JG, Phillips JD, Behrens EW, Lewis T, Lawver LA, Nakamura Y, GarciaAbdeslem J, Maxwell AE.  1996.  Heat flow in the western abyssal plain of the Gulf of Mexico: Implications for thermal evolution of the old oceanic lithosphere. Journal of Geophysical Research-Solid Earth. 101:2895-2913.   10.1029/95jb03450   AbstractWebsite

The seafloor depth of an oceanic basin reflects the average temperature of the lithosphere. Thus the western abyssal plain of the Gulf of Mexico, which has tectonically subsided much (> 1 lan) deeper than other basins of comparable ages (late Jurassic), should be underlain by an anomalously cold lithosphere. In order to examine this hypothesis, we made suites of high-accuracy heat flow measurements at 10 sites along a line connecting Deep Sea Drilling Project (DSDP) sites 90 and 91 in the Sigsbee abyssal plain. The new hear flow sites were initially surveyed by 3.5-kHz echo sounding, 4-channel seismic reflection, seismic refraction with eight ocean bottom seismometers, and nine piston cores. We occupied a total of 48 heat flow stations along the seismic survey line (3 to 6 at each site), including 28 where we measured in situ thermal conductivities over the practical depth interval (4 m) of the new multioutrigger bow heat flow probe. We determined the heat flow associated with the lithosphere by correcting the values measured at the seafloor (41 to 45 mW/m(2)) for (1) the thermal effect of the sedimentation and (2) the additional heat from the radioactive elements within the sediments. The sedimentation history, required for the first, was reconstructed at each heat flow site based on ages and thicknesses of the major seismic stratigraphical sequences, age data from the DSDP cores, 3.5-kHz subbottom reflectors, and correlation of turbidite units found in the piston cores. Radiogenic heat production was measured for 55 sediment samples from four DSDP holes in the gulf, whose age ranged from present to Early Cretaceous (0.83 mu W/m(3) on the average). This provided the correction for the second. The effects of these two secondary factors approximately cancel one another. The lithospheric heat flow under the abyssal plain thus estimated ranges from 40 to 47 mW/m(2). These heat flow values are among the lowest in the Mesozoic ocean basins where highly reliable data (45 to 55 mW/m(2)) have been reported. Therefore the lithosphere under the gulf seems indeed colder than that under other old ocean basins. However, it is not as cold as expected from the large tectonic subsidence. The inconsistency between the depth and heat flow may imply an anomaly in the regional thermal isostasy.

Grindlay, NR, Madsen JA, Rommevaux C, Sclater JG, Murphy S.  1996.  Southwest Indean Ridge 15°E-35°E: a geophysical investigation of an ultra-slow spreading mid-ocean ridge system. InterRidges News. 5:7-12. Abstract
Atwater, T, Sclater J, Sandwell D, Severinghaus J, Marlow M.  1993.  Fracture zone traces across the North Pacific Cretaceous Quiet Zone and their tectonic implications. The Mesozoic Pacific : geology, tectonics, and volcanism : a volume in memory of Sy Schlanger. ( Pringle MS, Sager WW, Sliter WV, Stein S, Eds.).:137-154., Washington, DC: American Geophysical Union Abstract
Nagihara, S, Sclater JG, Beckley LM, Behrens EW, Lawver LA.  1992.  High Heat-Flow Anomalies over Salt Structures on the Texas Continental-Slope, Gulf-of-Mexico. Geophysical Research Letters. 19:1687-1690.   10.1029/92gl00976   AbstractWebsite

We made 74 closely spaced (< 2 km apart) heat flow measurements around and over two salt structures on the Texas continental slope, Gulf of Mexico. The values outlined the shape of the heat flow anomalies over both structures. Based on a preceding high resolution seismic survey, we interpreted these structures to be a cylindrical plug and a salt tongue extending from the crest of a wall-shaped feeder. The heat flow observations clearly reflect differences between the two features and are consistent with the prior structural interpretation. The values over the salt plug are nearly all greater than 70 MW/m2. The measurements over the salt tongue have a sharp heat flow peak of 90 MW/m2 associated with the presumed feeder and rather uniform values around 60 MW/m2 over the remainder. The variation of heat flow over both structures is smooth and shows no apparent scatter. Heat flow values off these features are uniformly low, around 30 MW/m2. Thermal effects from bottom water temperature fluctuation, slope sedimentation, diapiric movement of the salt body, and pore fluid migration appear unable to provide a satisfactory explanation for the observations. However, thickness variations of a highly conductive salt body can easily account for the heat flow anomalies. We suggest that modeling of the conductive anomaly should provide substantial constraints on the bottom geometry of the salt.

Boerner, ST, Sclater JG.  1992.  Deformation under Extension of Assemblies of Steel Balls in Contact - Application to Sandbox Models. Journal of Geophysical Research-Solid Earth. 97:4969-4990.   10.1029/91jb02274   AbstractWebsite

Experiments on sandboxes provide a useful tool for understanding the deformation of continental crust. To understand the mechanics at the grain to grain level, we idealized the sand as an assembly of steel balls in contact. We performed a carefully constrained suite of experiments in two and three dimensions by stretching various assemblies of steel balls placed on a rubber sheet attached to moveable boundaries. Though dilation occurred in all the experiments, careful observation supplemented by theoretical treatments of both the two- and three-dimensional cases demonstrated that only the balls which started in a close-packed or approximately close-packed hexagonal arrangement deformed by failure along well-defined slip planes. In the two-dimensional close-packed state, preferential dilation gave rise to linear "ghosts" over single gaps or complex arches above the rubber sheet. Dropping of either close-packed or approximately close-packed triangular blocks in two or three dimensions created approximately 60-degrees faults, triangular horst, and trapezoidal grabens. Under certain conditions we also observed crosscutting faults, faults which died out along strike, and rotating, internally deforming fault blocks. Our experiments duplicate many of the features of sandbox models. We use the predicted behavior of an idealized arrangement of like spheres to explain the mechanical process by which the steel balls deform and compare our results directly with observations on similar experiments on sandboxes. Though sand grains and steel balls differ in size, unit density, interparticle coefficient of friction, roughness and angularity, we conclude that both the sand and the steel balls dilate as a result of deformation and form triangular fault blocks which move as coherent units. Further, we argue that close packing determines both the appearance and angle of faulting. Sandbox models are used to visually illustrate the deformation of both soft sediments and the much harder continental crust. The implicit assumption is that sand, soft sediments, and continental crust all deform by the same mechanism. We believe that the sandbox models may represent close to true scale models of the upper brittle continental crust if the mechanical process of deformation is the same. In addition, they may provide useful analogues for the deformation of sedimentary sequences. Finally, our model of sand deformation which stresses dilation and pervasive antithetic faulting provides a physical basis to current "pseudo-continuum" models for determining amounts of extension from fault dips and bed geometries in sedimentary basins.

Sclater, JG, et al.  1992.  The Alliance Exotique, Indidan Ocean plate reconstructions since the late Jurassic. The Indian Ocean : a synthesis of results from the Ocean Drilling Program. ( Duncan RA, Ed.).:471-475., Washington, D.C.: American Geophysical Union Abstract
Sclater, JG, Nagihara S.  1991.  Heat-Flow in the Caribbean and Gulf of Mexico - Comment. Journal of Geophysical Research-Solid Earth. 96:21807-21810.   10.1029/91jb00593   AbstractWebsite
Mueller, D, Sandwell DT, Tucholke BE, Sclater JG, Shaw PR.  1991.  Depth to basement and geoid expression of the Kane Fracture Zone: A comparison. Marine Geophysical Researches. 13:105-129. AbstractWebsite

Geoid data from Geosat and subsatellite basement depth profiles of the Kane Fracture Zone in the central North Atlantic were used to examine the correlation between the short-wavelength geoid ( lambda = 25-100 km) and the uncompensated basement topography. The processing technique we apply allows the stacking of geoid profiles, although each repeat cycle has an unknown long-wavelength bias. We first formed the derivative of individual profiles, stacked up to 22 repeat cycles, and then integrated the average-slope profile to reconstruct the geoid height. The stacked, filtered geoid profiles have a noise level of about 7 mm in geoid height. The subsatellite basement topography was obtained from a recent compilation of structure contours on basement along the entire length of the Kane Fracture Zone.

Lister, CRB, Sclater JG, Davis EE, Villinger H, Nagihara S.  1990.  Heat-Flow Maintained in Ocean Basins of Great Age - Investigations in the North-Equatorial West Pacific. Geophysical Journal International. 102:603-630.   10.1111/j.1365-246X.1990.tb04586.x   AbstractWebsite

Multipenetration heat flow measurements have been made at four sites in deep basins of the west–central Pacific Ocean: the West Mariana Basin, Central Mariana Basin, Nauru Basin and Central Pacific Basin. The final heat flows are, respectively, 46.6 ± 0.5, 49.4 ± 0.2, 44.2 ± 0.9 and 49.5 ± 1.1 mW m−2. Each site was surveyed by single-channel seismic reflection profiling, and provided a gravity core. The instrument measured thermal conductivity in situ over the entire depth intervals used for determination of the gradients, and the reduction scheme iterated conductivity and heat-capacity changes into the fitting procedure, both of entry frictional decays and of conductivity heat pulse decays. The absolute accuracy of the instrument should approach 2 per cent and the first site would make a good intercalibration standard for heat flow measurement. The heat flow variation between the sites is real, and there is also a significant variation in the isostatically reduced depths of the sites. There is no age progression of either depth or heat flow, and, when five other good multidata points are included, the relationship between depth and heat flow conforms to that expected from simple cooling models only in an average sense for the whole group. The most plausible explanation for the variations is that heat flow and thermal elevation are dependent on different levels of deep lithosphere reheating at different times between 70 and 120 Myr ago. It is suggested that additional topographic variation is caused by the different accumulations of sediment and lava flows at each site, and to errors in the isostatically reduced depths due to incomplete knowledge of the stratigraphy down to the crust–mantle interface. These explanations of the topographic variation could be tested by seismic refraction measurements.

Royer, JY, Sclater JG, Sandwell DT.  1989.  A Preliminary Tectonic Fabric Chart of the Indian-Ocean. Proceedings of the Indian Academy of Sciences-Earth and Planetary Sciences. 98:7-24. AbstractWebsite
Boerner, ST, Sclater JG.  1989.  Approximate solutions for the heat loss in small marginal basins. CRC handbook of seafloor heat flow. ( Wright JA, Louden KE, Eds.).:231-255., Boca Raton, Fla.: CRC Press Abstract