Sparse 3D seismic and magnetic imaging at Escondida porphyry copper mine, Chile

2021 ◽  
Vol 40 (2) ◽  
pp. 114-121
Author(s):  
Heather Schijns ◽  
Gabriel Madero ◽  
Jorge Bugueño ◽  
Andres Salazar ◽  
Todd Grant
Keyword(s):  
Low Cost ◽  
Porphyry Copper ◽  
Magnetization Vector ◽  
Copper Deposit ◽  
Seismic Survey ◽  
3D Seismic ◽  
Mining Operations ◽  
Porphyry Deposits ◽  
Magnetic Imaging ◽  
Airborne Survey

Seismic is often inferred to be synonymous with high cost. In a mineral environment, it is typically assumed to be viable only for mining operations or brownfield exploration. For greenfield exploration, other geophysical and geochemical/lithogeochemical methods are usually preferred, due in part to their affordability. We show results of a low-cost seismic survey over the Escondida porphyry copper deposit. The results show that low-cost 3D acquisition can improve structural understanding of established porphyry deposits and that there is potential for 3D seismic to be applied in brownfield and perhaps even greenfield exploration. The sparse 3D seismic reflection survey acquired at Escondida illuminates the structural setting and images stock genetically related to the Escondida intrusive complex at depth. The seismic results are compared to a magnetization vector inversion calculated from a regional airborne survey. This illustrates the potential for jointly utilizing the two methods to identify and prioritize anomalies for targeted drilling-based follow-up in exploration settings.

scholarly journals Tracking Cobalt, REE and Gold from a Porphyry-Type Deposit by LA-ICP-MS: A Geological Approach towards Metal-Selective Mining in Tailings

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 109 ◽  
Author(s):  
Germán Velásquez ◽  
Daniel Carrizo ◽  
Stefano Salvi ◽  
Iván Vela ◽  
Marcial Pablo ◽  
...  
Keyword(s):  
High Resolution ◽  
Porphyry Copper ◽  
Precious Metals ◽  
Copper Deposit ◽  
Mineral Deposit ◽  
Critical Metals ◽  
Mining Operations ◽  
Gold Silver ◽  
Selective Mining ◽  
Mineral Characterization

High-resolution mineral characterization performed on mine material from a giant porphyry copper deposit shows that critical and precious metals, such as cobalt, lanthanum, gold, silver, and tellurium, are concentrated in pyrite in the form of visible micro-inclusions, invisible mineral nano-inclusions, and trace metals in the mineral lattice. Visible and invisible inclusions consist of Ag-Au-Te sulfosalt and monazite-(La) particles. Trace metal concentrations grade up to 24,000 g/t for cobalt, up to 4000 g/t for lanthanum, and up to 4 g/t for gold. Pyrite, considered a waste material, is removed from the valuable copper ore material and sent to the tailings. Thus, tailings with high contents of pyrite can represent a prime target to explore for critical metals in the porphyry copper mining operations, transforming it into a new source of supply for critical metals. We propose that high-resolution mineral characterization is the key to evolve from a quasi-single-metal (copper) operation to a multi-metals business by developing metal-selective mining. To address this challenge, we coined the Metal-Zone concept to identify zones enriched in a specific metal within a mineral deposit, instead of zones enriched in an ore mineral.

scholarly journals An abrupt switch in magmatic plumbing taps porphyry copper deposit-forming magmas

2021 ◽  
Author(s):  
Lawrence Carter ◽  
Simon Tapster ◽  
Ben Williamson ◽  
Yannick Buret ◽  
David Selby ◽  
...  
Keyword(s):  
Porphyry Copper ◽  
Copper Deposit ◽  
Ore Deposits ◽  
Green Technology ◽  
Ore Formation ◽  
Porphyry Deposits ◽  
Order Of Magnitude ◽  
Magmatic Plumbing System ◽  
Lower Crustal ◽  
Melt Evolution

Abstract Porphyry-type deposits are a vital source of green technology metals such as copper and molybdenum. They typically form in subduction-related settings from large, long-lived magmatic systems. The most widely accepted model for their formation requires that mantle-derived magmas undergo a multi-million year timescale ramp-up in volatiles and ore-forming constituents in mid- to lower-crustal reservoirs, however this does not explain why porphyry deposits are absent from the vast majority of arc magmatic systems. To address this, we have carried out geochemical and geochronological studies on the tilted, ~8 km depth equivalent, cross-section through the classic Yerington magmatic system, Nevada. Here we show that the magmas underwent a major and abrupt change in chemistry over a period of 100 kyrs which is coincident with the initiation of ore formation. This is attributed to a wholesale switch in the magmatic plumbing system whereby volatile-rich granitic melts were extracted from an estimated ~30 km depth and transported to shallow levels (~3-8 km) where exsolving fluids were focussed through highly permeable pathways to form porphyry deposits. The change in magma chemistry is documented across the entire plutonic to volcanic record. Its rapidity suggests that the increase in a magma’s ore-forming potential is not solely driven by tectonic factors, that occur over multi-million year scales, but through internal processes within the melt evolution zone, operating at more than an order of magnitude faster than previously envisaged. This short timescale narrows the temporal-geochemical footprint of magmas associated with porphyry mineralisation which will aid in targeting the next generation of ore deposits.

The Forties and Brimmond Fields, Blocks 21/10, 22/6a, UK North Sea

2003 ◽  
Vol 20 (1) ◽  
pp. 557-561 ◽  
Author(s):  
A. Carter ◽  
J. Heale
Keyword(s):  
North Sea ◽  
Low Cost ◽  
New Technology ◽  
Horizontal Wells ◽  
Oil Price ◽  
3D Seismic ◽  
Rotary Drilling ◽  
Geological Society ◽  
Recoverable Reserves ◽  
Infill Drilling

AbstractThis paper updates the earlier account of the Forties Field detailed in Geological Society Memoir 14 (Wills 1991), and gives a brief description of the Brimmond Field, a small Eocene accumulation overlying Forties (Fig. 1).The Forties Field is located 180 km ENE of Aberdeen. It was discovered in 1970 by well 21/10-1 which encountered 119 m of oil bearing Paleocene sands at a depth of 2131 m sub-sea. A five well appraisal programme confirmed the presence of a major discovery including an extension into Block 22/6 to the southeast. Oil-in-place was estimated to be 4600 MMSTB with recoverable reserves of 1800 MM STB. The field was brought onto production in September 1975. Plateau production of 500 MBOD was reached in 1978, declining from 1981 to 77 MBOD in 1999.In September 1992 a programme of infill drilling commenced, which continues today. The earlier infill targets were identified using 3D seismic acquired in 1988. Acquisition of a further 3D survey in 1996 has allowed the infill drilling programme to continue with new seismic imaging of lithology, fluids and saturation changes. The performance of the 1997 drilling showed that high step-out and new technology wells, including multi-lateral and horizontal wells, did not deliver significantly better targets than drilling in previous years.In line with smaller targets, and in the current oil price environment, low cost technology is being developed through the 1999 drilling programme. Through Tubing Rotary Drilling (TTRD) is currently seen as the most promising way of achieving a step

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