Hey Wack.
Courtesy of @Ludbucker on CEO.ca
Does any of this sound familiar to any of my previous rantings about a Pilbara and Wits supervolcano Caldera. Love to hear yours and others thoughts.
@ludbucker @kuston, As you can see from this piece:
http://www.novoresources.com/_resources/presentations/technical-report.pdf, Beaton's does have conglomerate-hosted gold but it's of a different age and it's on a different side of the basin - all amounting to an inferior amount compared to what is associated with the West and Central mineralization. What has enhanced the Karratha area is what makes the Pilbara puzzle so fascinating. For instance, take a look at this map and notice the tight concentric rings with the red dot in its center just to the northwest of Karratha:
http://www.ga.gov.au/webtemp/image_cache/GA7069.jpg+ or notice the same red dot on this Pilbara gravity map:
http://pilbara.mq.edu.au/wiki/Image:Pilbara_gravity.jpg+ Now, what if that is evidence of a shield/caldera volcano that resulted from a superplume event? There's plenty of evidence of a global superplume event around the Mt. Roe Basalt time period:
https://www.sciencedirect.com/science/article/pii/S0264370702000224 and
http://www.largeigneousprovinces.org/04dec. My overall point is Quinton recognized something very unique when he saw the Artemis picture of that one watermelon seed nugget...so, much so that he made the phone call from Denver to Australia and ordered a relentless staking of ground south of Purdy's into the Fortescue Basin. It must have been something unique and special compared to Beaton's and all indications are that his instincts were more than correct. The magnitude of what he's "stumbled" upon seems to escape plenty as the primary focus seems to instead be on our little price correction and our elusive assays. While temporarily frustrating, temporary those will be. Exciting times ahead for the patient big-picture-thinking investors...
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#nvo, about 11 hours ago
@Dunite @ludbucker, another poster ole
@zentrarian, has stated that I have evolved in my thinking. Well, many months ago, as a member of the "peanut gallery" I had mentioned much of what you have posted. So it would seem that EVERYBODY'S thinking has evolved and changed as new data from the field has presented itself. I would add the gravity anomaly looks like a ring dyke. Which would be as you have stated a remnant signature of a volcano. The bouguer signature does show a deep seated root.
@ludbucker, you might want to check out for comparison the bouguer signature of the Duluth Complex. It is a "LIP" in a rift type environment that had a mantle plume event involved. It has the highest gravity signature on the North American continent. Precious metals are present in that complex....One other thought. In order to have gold nuggets of one size, then they were derived from a magma that cumulated out. In other words, crystals of different minerals dropped out when they reached a certain size as the magma in the chamber cooled and reached certain temperatures. So the gold fractionated out when a certain size was obtained and could not stay floating the melt when the melt reached a certain temperature. Six months from now, when more data comes in, even this thinking may have changed......
Abstract
The 2714–2709 Ma Ventersdorp Supergroup overlies Mesoarchaean basement rocks and sedimentary strata of the Neoarchaean Witwatersrand Supergroup. The latter basin was inverted by tectonic shortening and suffered the loss of up to 1.5 km of stratigraphy prior to deposition of the Ventersdorp volcanics. Thermal uplift and fluvial incision prior to the basal Klipriviersberg Group flood basalts appear to have been limited, but this could also reflect a hot dry palaeoclimate acting on a peneplained plateau. Rapid ascent of ponded magma beneath thinned sub-Witwatersrand lithosphere, transported laterally from a mantle plume starting head possibly situated marginally to the Kaapvaal craton is inferred for this unit of up to 2 km of predominantly tholeiitic basalts with subordinate, basal komatiites. Crustal extension related to ascent of the ponded magma followed, leading to the formation of a set of graben and half-graben basins, in which immature clastic sedimentary, and felsic to mafic lavas and pyroclastics of the Platberg Group were laid down. The Platberg basins show no evidence for reactivation of pre-existing crustal structures. The Fortescue Group of the Pilbara craton has an analogous lower flood basaltic succession, followed by graben-fills similar to those of the Platberg Group. Differences in the Fortescue include evidence for significant thermal uplift prior to the onset of volcanism, subaqueous basalts in the south of the Pilbara craton, evidence for two episodes of flood basaltic volcanism, possibly related to two plumes at c. 2765 and 2715 Ma, and graben basins aligned along existing cratonic structures. Both Kaapvaal and Pilbara flood basalts and graben-related sedimentary-volcanic deposits are thought to have been part of a c. 2.7 Ga global superplume event. The plume inferred for the Fortescue Group flood basalts was probably related to rifting and the breakup of a plate larger than the preserved Pilbara craton. Uppermost Ventersdorp units (Bothaville Formation terrestrial clastic and Allanridge Formation tholeiitic rocks) suggest a combination of thermal subsidence, allied to continued plume (minor komatiites) and graben basin influences. In the Kaapvaal craton, the Transvaal Supergroup lies unconformably above the Ventersdorp. Basal “protobasinal” successions reflect discrete fault-bounded basin-fills, analogous to those of the Platberg Group; however, it is inferred that the former depositories were related to craton marginal plate tectonic influences, specifically the c. 2.6 Ga Limpopo orogeny. Thin fluvial sheet sandstones of the Black Reef Formation unconformably succeed the protobasinal rocks and reflect the transition to an epeiric drowning of much of the Kaapvaal craton. A shallow shelf carbonate-banded iron formation platform succession (Chuniespoort-Ghaap Groups) developed in two sub-basins on the Kaapvaal craton. They are mirrored by the approximately coeval Hamersley chemical epeiric sediments on the Pilbara craton, and both Kaapvaal and Pilbara transgressive successions are related here to a possible second, c. 2.5 Ga superplume event, which raised sea levels globally. Evidence for the younger superplume event is less clear than for the c. 2.7 Ga event.
Thanks to all for entertaining this possible Volcano Caldera theory apparently I'm not the only one who shares it.
Big thanks to @Ludbucker/CEO.ca for this contribution.
I once again defer to the forum et al.
Night folks vacation over!
Cheers
(20min delay)