L047 Rosedale seismic survey, VIC, 1961

Between February and April 1961 the Bureau of Mineral Resources, Geology and Geophysics made a seismic survey in the Rosedale area of the Latrobe Valley, partly at the request of the State Electricity Commission of Victoria to provide more information about the brown coal measures in this area, and partly in order to test the Bureau's latest seismic recording equipment. One traverse, combining both reflection and refraction profiling techniques, was run south from the A.P.M. No.1 bore at Rosedale as far as Merrimans Creek, and a second traverse was run west from the bore as far as Toongabbie. Results show that the maximum thickness of the Tertiary sequence is about 3000 ft and that it thins gradually to 1000 ft at Toongabbie and rapidly to about 750 ft on the Baragwanath Anticline. It is shown that early Tertiary deposits were laid over the whole area but have been uplifted and partly eroded in late Tertiary or post-Tertiary times in the Toongabbie and Baragwanath areas, but the main syncline sank and accumulated thick Tertiary sediments. Results show alao that on the northern flank of the Baragwanath Anticline where crossed by the seismic lines the Tertiary and Jurassic sediments are steeply folded but not necessarily faulted. No positive information was obtained below 4500 ft but long refraction shots suggest that a high-velocity basement does not exist at a depth less than 12,000 ft.

1961年2月至4月间，矿产资源、地质与地球物理局（Bureau of Mineral Resources, Geology and Geophysics）在拉特罗布谷（Latrobe Valley）的罗斯代尔（Rosedale）区域开展了地震勘探工作。本次勘探一方面应维多利亚州电力委员会（State Electricity Commission of Victoria）的请求，以获取该区域褐煤系地层的更多相关资料，另一方面也用于测试该局最新的地震记录设备。一条结合反射与折射剖面技术的测线从罗斯代尔的APM一号钻孔（A.P.M. No.1 bore）向南延伸至梅里曼斯溪（Merrimans Creek），另一条测线则从该钻孔向西延伸至通加比（Toongabbie）。勘探结果显示，第三系（Tertiary）地层的最大厚度约为3000英尺，在通加比地区逐渐减薄至1000英尺，而在巴拉格万背斜（Baragwanath Anticline）处则迅速减薄至约750英尺。研究表明，早第三纪沉积曾覆盖整个研究区域，但在晚第三纪或后第三纪时期，通加比与巴拉格万区域的地层发生抬升并遭受部分侵蚀，而主向斜则发生沉降并堆积了巨厚的第三系沉积物。此外，在地震测线穿过的巴拉格万背斜北翼，第三系与侏罗系（Jurassic）地层发生了强烈褶皱，但未必存在断层。在4500英尺深度以下未获取到有效勘探信息，但长距离折射放炮结果显示，深度小于12000英尺的范围内不存在高速基底。