L044 Winton seismic survey, QLD, 1960

Towa.:ccis the end of 1960 , the Bureau. of Mineral Resources, Geology and Geophysics made a brief seismic survey in the Winton area of Queensland to resolve an apparent contradiction between the interpretations of gravity and aeromagnetic results previously obtained in the area. Gravity and aeromagnetic results both suggested the occurrence of a large fault or fault zone about 20 miles north-west of Winton, but the gravity and aeromagnetic interpretations differed regarding the direction of throw of the fault. A nine-mile seismic reflection traverse was surveyed across the supposed fault. The seismic results indicate the presence of a large fault or monoclinal fold with dowthrown side nouth-wast as suggested by the gravity values and also a smaller fault or monocline about two miles south-east with downthrown side south-east. The variations in thckness of Mesozoic rocks caused by these features were insufficient to explain the observed Bouguer gravity anomaly values, but the seismic results left open the possibilitues that there may be a considerable thickness of pre-Mesozoic sedimemts north-west of the main monocline or fault. It is postulated that the steep gravity gradient observed may be due to a large fault whose main movement took place in pre-Mesozoic times. Indications are that there is 5000 to 6000 ft of Mesozoic sediments in tha area.

1960年年末，矿产资源、地质与地球物理局（Bureau of Mineral Resources, Geology and Geophysics）为解决此前在昆士兰州温顿地区获取的重力与航空磁测结果解释之间的明显矛盾，在该区域开展了一次简短的地震勘探。此前的重力与航空磁测结果均显示，在温顿西北约20英里处存在一条大型断层或断层带，但二者对该断层的滑距方向解释存在分歧。研究人员沿推测的断层布设了一条长9英里的地震反射测线（seismic reflection traverse）。地震勘探结果表明，区域内存在一条大型断层或单斜褶皱（monoclinal fold），其下降盘（dowthrown side）位于西北方向，与重力值的推断一致；同时在东南方向约2英里处还存在一条小型断层或单斜构造，其下降盘位于东南侧。上述构造造成的中生代（Mesozoic）岩石厚度变化，不足以解释观测到的布格重力异常（Bouguer gravity anomaly）值，但地震结果仍存在一种可能性：主单斜构造或断层的西北侧可能存在厚度可观的前中生代（pre-Mesozoic）沉积物。研究推测，观测到的陡峭重力梯度可能源于一条大型断层，其主要活动发生在前中生代时期。本次数据集显示该区域的中生代沉积物厚度约为5000至6000英尺。