Nguồn gốc của tinh thể PGE có grade cao, sulfide thấp trong W Horizon, phức hợp Coldwell, Canada: mô hình định lượng cho khoáng sản kiểu rạn san hô trong các lớp magma đồng hình

Springer Science and Business Media LLC - Tập 56 - Trang 1151-1176 - 2021
Yonghua Cao1,2, David Good2, Robert Linnen2, Iain Samson3, Ryan Ruthart4
1Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China
2Department of Earth Sciences, Western University, London, Canada
3Department of Earth and Environmental Sciences, University of Windsor, Windsor, Canada
4Department of Earth Sciences, The University of Waterloo, Waterloo, Canada

Tóm tắt

W Horizon là một vùng mỏng liên tục của khoáng sản PGE (nguyên tố nhóm platin) grade cao, sulfide thấp trong gabbro Two Duck Lake tại mỏ Marathon Cu-PGE, phức hợp Coldwell, Canada, có hình dáng giống như các mỏ PGE kiểu rạn san hô trong các sự xâm nhập lớn hơn nhiều. Mỏ Marathon trước đây đã được chứng minh là đã phát triển thông qua việc tích tụ các sự xâm nhập dạng sill mang sulfide trong thời kỳ đồng hình, hình thành nên ba loại khoáng sản: W Horizon, Main Zone và Lower Zone. Mỗi vùng có thể được phân biệt bởi các đặc điểm như tập hợp khoáng vật sulfide hoặc khoáng vật nhóm platin, hoặc thông qua các giá trị Cu/Pd, Pd/Se và Pd/Au. Ví dụ, W Horizon được xác định bởi sự hiện diện của bornite, giá trị PGE rất cao, Cu/Pd thấp (< 1000), và Pd/Au cao (34 ± 32), trong khi các loại Main Zone và Lower Zone được đặc trưng bởi tỷ lệ Cu/Pd kiểu manti (1000 đến 10,000) và Pd/Au là 10.3 ± 4.7. Các phép tính mô hình dựa trên nâng cấp hòa tan đa giai đoạn Kerr-Leitch cho thấy sự gia tăng PGE và sự phân tách PGE khỏi Au và các yếu tố chalcophile trong W Horizon có thể liên quan đến việc nâng cấp và tái chế liquid sulfide thông qua các xung magma silicate liên tiếp. Đối với W Horizon, sự gia tăng cực kỳ PGE có thể được giải thích bởi sự tương tác của một liquid sulfide với tối đa 25 xung magma và sự hòa tan đồng thời của liquid sulfide dẫn đến mất > 95% liquid sulfide ban đầu. Trong một số mẫu, sự phong phú của kim loại và lưu huỳnh chỉ ra rằng PGE đã được vận chuyển dưới dạng các pha TABS-PGE. Công trình này mô tả một ví dụ của các sự tiêm kiểu sill giàu PGE mỏng có thể có tầm quan trọng đối với việc khám phá PGE ở những nơi khác.

Từ khóa

#PGE #khoáng sản #W Horizon #Coldwell Complex #sulfide thấp #magma đồng hình

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