Alternative explanations at Dresser

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Alternative explanations at Dresser


This is a transcript of a QuickTime movie (13.1 MB) recorded in the Pilbara in 2005. Professor Malcolm Walter, Director of the Australian Centre for Astrobiology, and Dr Martin Van Kranendonk, of the Geological Survey of Western Australia, discuss alternative explanations for the stromatolites at the Dresser formation.

Transcript:

If it's non biogenic the most likely explanation would be that it was a seafloor precipitate, but the association with rippled sands and there are some dessication cracks here too, aren't there, up in there?

Yes, there are dessication cracks.

It puts it in a sedimentary context just like the context of modern stromatolites in places like Shark Bay, so that there is no surprise really in terms of what we know about the paleo environment. It's not like a deeper marine seafloor precipitate that some people have seen elsewhere in rocks of similar ages, but it could be. It’s one of those examples of something that can’t be irrefutably interpreted at the present stage.

And one of the problems that we tried to address last year is that we are looking at deeply weathered material here. You see a lot of black and red iron oxide that may or may not have been the primary mineral that was precipitated in these very wrinkly mats and stuff. There have been drill cores through this unit taken back in the seventies but no one is really sure of the location of that core and now it's all fallen over, and we’ve really lost that information. So we did a drilling program with a colleague from France last year to get fresh material and we are just starting to work on that. We are hopeful that it might help address some of these questions.


Contents


Introduction

Context

Early Life

Evidence

Acknowledgements

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