Spinifex biogeochemical expressions of buried gold mineralisation: The great mineral exploration penetrator of transported regolith

A major challenge for mineral explorers is to efficiently detect mineralisation beneath the weathered cover that extends across the landscape. Determination of the elemental composition of plants (biogeochemical exploration) can aid in the detection of buried ore deposits due to their root penetration through the weathered cover. At the coyote prospect in Western Australia a range of plant species were sampled traversing a buried Au orebody. Here it is shown that the soft spinifex (Triodia pungens) accumulated important pathfinder elements related to the mineralisation, which produced a multi-element surficial expression of the underlying ore deposit. Spinifex grasses are one of the most widespread grasses over the Australian continent and have vertical root systems that can extend for many 10s of metres through sedimentary cover and interact with buried mineral deposits and alteration zones in the underlying substrate. Spinifex biogeochemistry therefore has potential to be a low cost, low environmental impact, sampling medium for mineral exploration programs across large parts of arid Australia. The examination of similar grasses from other semi-arid and arid regions from around the world therefore also warrants further investigation.     

A model for the prediction of in-line vortex-induced vibrations of cylindrical elements in a non-uniform steady flow

The method presently adopted in the offshore industry for predicting the amplitude of vibration of circular cylinders undergoing in-line vortex-induced excitation is demonstrated to be valid only for structures in uniform flows at sub-critical Reynolds numbers.A model which predicts the response of structural elements experiencing this phenomenon where the diameter, mass, and velocity of flow varies along the length of the structure is presented. Comparison between the results of this method and available experimental measurements is made.The model is structured to be an easily applied design tool producing an upper-bound estimate.     

A review of three transform margins off eastern Canada

 The southwest Newfoundland transform margin has been studied by deep seismic reflection and refraction. Lower crustal reflectivity strengthens towards the margin, where there is a shear zone of thinned continental crust overplated with oceanic material. The reflectivity may be due to shear fabrics in the crust. Crustal thinning probably took place by flow in the lower crust. The Ungava transform margin has been less studied but has been explored and drilled. It appears more volcanic in character. The north Baffin region has undergone a complex tectonic history and provides an example of the transition from continent–ocean to continent–continent transform motion. Received: 9 March 1995 / Revision received: 25 July 1995     

THE NAKHLITES PART II: WHERE,WHEN, AND HOW

The Nakhla and Lafayette meteorites are pyroxenite cumulates that show no simple relation to chondrites, basaltic achondrites, or lunar rocks. They present evidence of magmatic activity occurring on a highly differentiated parent body relatively late in the history of the solar system similar in some respects to the Earth.