Any geo's looked closley at these two projects? Beyond their geographical proximity, from what I have read from ESR, they note a Noni as a "Cretaceous bedded unit of over 100m thickness" which is the same as Groote.
ESR:
The Noni Formation occurs as part of the Banda Terrane and has been mapped across Estrella’s project for over 27km. It is described as a Middle Jurassic to Cretaceous bedded unit of over 100mthickness comprising arenites and chert beds within there has been found massive manganese and ferromanganese bands and nodules.
Orebody/occurrences: primary mineralisation existsas pisolithic concretions and directprecipitates within deep-sea limestones.
South 43: Groote Eylandt lies on the eastern margin of the Proterozoic McArthur Basin. The ore deposit is developed within flat lying Cretaceous rocks deposited unconformably on a basement of Palaeoproterozoic crystalline rocks and Mesoproterozoic quartzites.
The Cretaceous rocks may exceed 100m in thickness and comprise early to middle Cretaceous Mullaman Formation sediments deposited in two small local basins.
Orebody/occurrences: The orebody comprises mainly primary pisoliths and ooliths which occur as an almost continuous layer some 22 km long, 6 km wide and up to 9 m, but averaging 3 m thick within the sandy layers of the Mullaman Formation.
Source:
Groote Eylandt - https://portergeo.com.au/database/mineinfo.asp?mineid=mn540
(20min delay)