Isotherm Depth Research Articles

XBT Measurements of Thermal Gradients in the MODE Eddy

Abstract Estimates of the repeatability and accuracy of XBT measurements were made using XBT data taken during MODE. The XBT observations of the depth of isotherms had systematic errors of up to 15 decibars (by comparison to simultaneous CTD drops) as well as random errors on the order of 8 declare. Maps of these observations show small-scale thermal structure which would imply sizeable increases in geostrophic shears.

Potentially Petroliferous Trends in Florida as Defined by Geothermal Gradients: ABSTRACT

A newly constructed geothermal gradient map of Florida suggests both the presence of areas with high petroleum and the thickness of the potentially petroliferous section. The base of the potential section is defined by the depth of the basement, and the top is defined by the depth at which the minimum temperature exists for petroleum maturation. From previous studies this upper limit is assumed to coincide with the 221°-isotherm depth. A potential section map has been prepared which includes all of the presently productive fields and new discoveries within favorable areas. Locations of thick sediment sections of proper temperature for oil occurrence are: the Western Panhandle, a small area of the central Panhandle, and the extreme southwestern part of t e peninsula. Over most of central and north Florida and in the southern Keys the basement may be penetrated before encountering the requisite minimum temperature for petroleum maturation. Tests in these areas run a higher probability of being barren. End_of_Article - Last_Page 1698------------

Formation of Magnetic Anomaly Pattern of Mid-Atlantic Ridge

Summary Surveys of the crest of the Mid-Atlantic Ridge and similar portions of the other mid-ocean ridges characteristically reveal a pattern of magnetic anomalies which have an elongation of about 4:1 parallel with the median line of the ridge. The linear pattern can be roughly simulated by a model in which steep-sided blocks within the oceanic crust between the sea floor and the depth of the Curie point isotherm have alternately normal and reversed directions of remanent magnetization. Vine & Matthews (1963) suggested that this structure might be due to the continued injection of basaltic feeder dykes along the median line of the ridge, each dyke shouldering aside its predecessors and being magnetized in the direction of the Earth's magnetic field. As the direction of the Earth's field reverses periodically this mechanism can account in a crude way for the formation of the model. A survey of the crest of the Mid-Atlantic Ridge at 45° N (Loncarevic, Mason & Matthews 1966) showed a less regular pattern of blocks suggesting that the mechanism of dyke injection is less regular than that utilized in the original theory. It seems plausible that dyke injections do not always occur precisely along the median line but are scattered about it. An analogue model experiment involving marbles, and a computer program written for titan are used to investigate the consequence of such scatter. First results indicate that the great majority of dyke injections must occur within the width of the median valley; the standard deviation of the distribution of dykes (assumed normal) must be less than about 5 km (half the width of the median valley).

OBSERVATIONS ON INTERNAL WAVES IN SHALLOW WATER

Observations made off the San Diego coast in 1959 are presented and discussed. Two different systems for recording temperatures were employed and thermistors were used in both of them. The transducer component of one consists of several thermistors by which temperature is measured at fixed depths. The other system includes a sea element which is automatically and continuously positioned on a selected isotherm. Ocean temperature was simultaneously recorded at three locations. Series of internal waves of relatively high frequency usually follow high or low tide and persist for approximately one hour. Single waves that are separated from other significant thermal disturbances and not related to any particular phase of tide progress in the same area. Profiles of both types of waves show that they are strongly influenced by boundary conditions. Wave displacement is upward when the thermocline is near the bottom and downward when the thermocline is higher. Internal tides are present throughout a 7‐day record of isotherm depth. The phase relation between the surface tide and internal tide is variable over time but the period and asymmetry of the two waves are similar.

Geothermal Variations in Oil Fields of Los Angeles Basin, California

Data obtained from temperature measurements in oil wells of the Los Angeles basin are presented, and some causes of abnormal temperature conditions and factors affecting the interpretation of geothermal data are noted. The relations of geothermal gradients and isothermal depths to structure are discussed for the Santa Fe Springs, Long Beach, and Torrance fields. Variations in the geothermal constants are considered with respect to the geology of the region, and the possible correlative value of temperature data is suggested.