The characteristics and origin of the Hoidas Lake REE Deposit
The Hoidas Lake Rare Earth Element (REE) Deposit is one of several REE showings which are spatially associated with a regional-scale fault system that cuts through the Rae Province in northern Saskatchewan. The showings occur along the Hoidas-Nisikkatch fault, believed to be a subsidiary of the Black Bay Fault, and consist of multiple REE-enriched veins. Surface outcrops and drilling have delineated a vein system, called the JAK zone, which extends for over 1 km along strike, with the system remaining open both along strike and down dip. The majority of the REE are hosted by fluorapatite and allanite-(Ce), although there are also minor amounts of monazite, bastnaesite and chevkinite which can contain significant concentrations of REE. The veins are dominantly LREE-enriched, specifically La, Ce, and Nd. The mineralization at Hoidas Lake is complex, with the chemical and mineralogical compositions changing with each vein generation. The earliest veins consist of REE-bearing allanite and chevkinite which occur in association with clinopyroxene, titanite, and hyalophane. The allanite-rich veins are followed by veins dominated by red or green apatite, both of which are typically brecciated. Finally, there is a late apatite which crosscuts all previous vein generations. Each of the distinct apatite generations shows discrete chemical variations, particularly in their light rare earth element content, with the total rare earth oxide content ranging from approximately 1.5% in the oldest apatite to as much as 5% in the green apatite. The majority of the apatite and allanite crystals are strongly zoned, reflecting the chemical changes in the mineralizing system through time and, particularly in the earliest vein generations, there are signs of hydrothermal alteration. The early apatite generations typically show the development of monazite inclusions which suggests interaction with hydrothermal fluids, as do the REE-poor rims and bastnaesite alteration observed in the majority of the allanites. The veins are fault controlled and are interpreted to be late magmatic- hydrothermal in origin, with the fluid derived from a magmatic source at depth. Although the exact source of the fluids remains uncertain, the high concentration of REE, as well as Sr and Ba, and a relative depletion in high field strength elements suggests that the mineralization may be related to either an alkali or carbonatitic source.
Allanite, Apatite, Rare Earth Elements
Master of Science (M.Sc.)
Hoydas Lake Rare Earth Element (REE) ni moja ya maeneo kadhaa ya REE ambayo yanahusishwa na mfumo wa kosa la kikanda ambao hupitia Mkoa wa Rae kaskazini mwa Saskatchewan. Maonyesho hayo yanatokea kando ya Hoidas-Nisikitch fault, ambayo inaaminika kuwa kampuni tanzu ya Black Bay Fault, na inajumuisha mishipa mingi iliyotajwa na REE. "Mchimbaji wa maji na uchimbaji wa maji umeweka mfumo wa ""vini"" unaoitwa ""JAK zone"" ambao unaenea kwa zaidi ya kilomita moja kwenye mteremko, na mfumo huo unabaki wazi katika mteremko na chini ya mteremko." REE huhifadhiwa na fluoropathite na allonite, ingawa kuna kiasi kidogo cha monazite, bastonite na chevkinite ambayo inaweza kuwa na viwango muhimu vya REE. Mishipa ni hasa LREE-kutajirishwa, hasa La, Ce, na Nd. Umineria katika Ziwa Hoidas ni tata, na kemikali na mineralogical muundo kubadilisha na kila kizazi mshipa. Vituo vya kwanza vya REE vina Allanite na Chevkinite ambayo hutokea kwa kushirikiana na clinopyroxene, titanite, na hyalophane. Mifupa yenye kiasi kikubwa cha allaniti inafuatwa na mifupa yenye kiasi kikubwa cha apatiti nyekundu au kijani, ambayo kwa kawaida huwa na rangi ya brechi. Hatimaye, kuna apatite ya marehemu ambayo hupitia vizazi vyote vya mshipa wa awali. Kila moja ya vizazi tofauti vya apatite inaonyesha tofauti za kemikali, haswa katika maudhui yao ya elementi nyepesi ya ardhi nadra, na jumla ya madini ya oksidi ya ardhi nadra kuanzia karibu 1.5% katika apatite ya zamani hadi 5% katika apatite ya kijani. Matofali ya apatite na alanyiti yana mikoa mikubwa, ikionyesha mabadiliko ya kemikali katika mfumo wa madini kwa muda, na haswa katika vizazi vya mapema vya mshipa, kuna ishara za mabadiliko ya hydrothermal. Mifumo ya awali ya apatite inaonyesha maendeleo ya monazite inclusions ambayo inaonyesha mwingiliano na hydrothermal fluids, kama vile REE-masikini rims na bastnaesite mabadiliko aliona katika wengi wa allanites. Mifupa ni kosa kudhibitiwa na ni kutafsiriwa kuwa marehemu magmatic- hydrothermal katika asili, na kioevu inayotokana na chanzo magmatic katika kina. Ingawa chanzo halisi cha kioevu bado haijulikani, mkusanyiko mkubwa wa REE, pamoja na Sr na Ba, na upungufu wa kiasi katika vitu vya nguvu ya uwanja wa juu, unaonyesha kwamba madini yanaweza kuhusiana na chanzo cha alkali au carbonatite. Allanite, Apatite, Rare Earth Elements Mwalimu wa Sayansi (M.Sc.)