Navigating TerraEye: An In-Depth Guide to Mineral Exploration Using Sentinel-2 and EMIT Data

In the complex field of mineral exploration, the ability to analyze vast amounts of satellite data accurately and efficiently is a key competitive advantage. TerraEye, a cloud-based application, provides advanced tools to process and interpret satellite data, particularly from Sentinel-2 and EMIT sensors. This blog post offers a detailed guide on how to navigate TerraEye, focusing on data processing and how to interpret the results of automated analyses. Additionally, we'll cover how to order additional datasets and request further processing of your Area of Interest (AOI) directly within the app.

How to Get Started with TerraEye

Getting started with TerraEye is straightforward:

1. Sign Up: Create an account on the TerraEye website by entering your details and agreeing to the terms of service.
2. Log In: Use your credentials to access the TerraEye dashboard.
3. Explore Demo Sites: Familiarize yourself with TerraEye’s features by exploring the demo sites available on your dashboard.
4. Create a New Order and Subscribe: Set up your first exploration project by defining your AOI, selecting the appropriate data processing options, and subscribing to the service.

Focus on Data Processing: Sentinel-2 and EMIT Data

At the heart of TerraEye's capabilities is its powerful data processing engine, which allows users to extract meaningful insights from satellite data. The platform offers two primary data sources: Sentinel-2 and EMIT, each with distinct strengths and considerations. Sentinel-2's data main advantage is the high resolution multispectral Visible and Near Infrared (VNIR) coverage, while EMIT ?offers high spectral resolution data for VNIR and Short-Wave Infrared (SWIR) ranges. The VNIR range is especially useful for recognition of iron-rich minerals, while the SWIR range is utlized to detect minerals containing Al, Si and Mg, such as silicates, sulfates, or hydroxides.

1. Sentinel-2 Data Processing

Sentinel-2 is a multi-spectral imaging mission from the European Space Agency (ESA), capturing data non-continuously(multispectral) across 13 spectral bands, 9 in the VNIR region and 3 within the SWIR region. Sentinel-2's 9-band coverage of the Visible and Near Infrared spectrum has been proven to provide excellent insights into mapping minerals rich in iron, such as goethite, hematite, pyroxenes, or olivines, as Fe shows spectral features in this wavelength range. Combination of such spectral resolution with spatial resolution going down to 10 meters per pixel, allows obtaining great results with high confidence level.

Key Points on Sentinel-2 Data Processing:

Considering the possibilites of Sentinel-2's VNIR range utilization, iron oxides and hydroxides are the perfect candidates for mineral mapping using this dataset. Iron oxides and hydroxides as well as pyroxenes and olives are considered to be indicator minerals for number of ore deposits:

o?? Porphyry Copper Deposits (PCD)

o?? Ultramafic-Hosted Deposits

o?? Lateritic Deposits

o?? Lithium-Bearing Pegmatites

o?? Hydrothermal Gold Deposits

o?? Iron Oxide Copper Gold Deposits (IOCG)

Assumptions and Challenges in Sentinel-2 Data Processing:

• Assumption 1: Some minerals may return similar hotspots due to spectral similarities. For example, Epidote and Chlorite can both appear in the same hotspots, complicating the interpretation.
• Assumption 2: TerraEye does not distinguish between different minerals within the same group (e.g., various types of amphiboles) when using Sentinel-2 data, focusing instead on broader groupings.
• Assumption 3: Proper masking is essential to reduce false positives, particularly in vegetated or urban areas. Masking removes non-mineral features, enhancing the accuracy of mineral detection.

Geological Spectral Indices:

• Indices targeted for iron-rich minerals detection: Sentinel-2 data is used to generate indices that highlight the presence of clay minerals, which are important in identifying alteration zones. In our approach we utilize indices such as Fe-silicate, Fe2O3, and Fe-3
• Indices targeted for detection of alteration minerals: Sentinel-2 data allows to identify alteration zones. In this case we use indices such as: Gossan Index, ALT index (alterations).

2. EMIT Data Processing

The Earth Surface Mineral Dust Source Investigation (EMIT) instrument provides hyperspectral imaging data, offering much finer spectral resolution than Sentinel-2, as band coverage for VNIR and SWIR wavelenghts is continuous (hyperspectral) EMIT data is especially valuable for distinguishing between closely related minerals and detecting subtle spectral features, thanks to high spectral resolution. This means that spectral data sampling in the SWIR and VNIR wavelenghts is quite dense and consequently more information can be derived from it.

Key Points on EMIT Data Processing:

• Enhanced Mineral Detection: EMIT’s hyperspectral data allows for more precise detection of minerals within specific deposits, such as:
• Porphyry Copper Deposits (PCD): Enhanced detection of mica group minerals (muscovite, biotite, illite, sericite), iron oxides and hydroxides (hematite, magnetite, goethite), clay minerals (kaolinite, montmorillonite, illite), jarosite, epidote group minerals, chlorite group minerals using the detailed spectral information from EMIT.
• Ultramafic-Hosted Deposits: EMIT’s capability toidentifyminerals of serpentine group, olivine, pyroxene, apmhiboles, chlorites, and talcenhances the accuracy of ultramafic deposit exploration.
• Lateritic Deposits: EMIT improves the detection of minerals like gibbsite and magnesite, as well clay minerals and iron oxides and hydroxides, which are critical in lateritic nickel and bauxite deposits.
• Lithium-Bearing Pegmatites: EMIT allows for better identification of minerals like lepidolite, sericite, or clay minerals , which are essential for lithium exploration.
• Hydrothermal Gold Deposits: Enhanced detection of sericite, sulfates, and clay minerals ?help in mapping hydrothermal gold systems.
• Iron Oxide Copper Gold Deposits (IOCG): EMIT’s data helps identify outcrops rich in minerals such as apatite, sericite, iron oxides, pyroxenes aiding in the exploration of IOCG deposits.

Assumptions and Challenges in EMIT Data Processing:

• Assumption 1: Similar to Sentinel-2, some minerals might produce overlapping hotspots due to spectral similarities, though this is mitigated by EMIT’s finer spectral resolution.
• Assumption 2: EMIT allows for some distinction between minerals within the same group, providing more granular insights than Sentinel-2.
• Assumption 3: EMIT data is not universally available as the mission is mainly focused on arid areas; the availability of this data may vary depending on your AOI.
• Assumption 4: As with Sentinel-2, proper masking is essential to avoid false positives, especially given EMIT’s high sensitivity to minor spectral features.

Geological Spectral Indices:?

• Advanced Indices: With EMIT data TerraEye can calculate more sophisticated geological indices that go beyond what Sentinel-2 can offer, such as indices for iron oxides and phosphate minerals, crucial for specific deposit types.

AI Clusters

Unsupervised machine learning methods applied to the satellite hyperspectral data provide the unbiased insight into the spectral nature of your area. TerraEye analyses the hyperspectral data for the number of clusters select by you. The generated map with the optimized interactive visualization give you the new perspective of the region and help you to validate your assumptions about geological situation. Compare this data layer with others from TerraEye to have the broader understanding.?

Interpreting TerraEye’s Results

Once TerraEye has processed your Sentinel-2 and EMIT data, it generates detailed maps and reports that highlight potential mineralization zones within your AOI. Here’s how to interpret these results:

1. Hotspot Analysis:

• Sentinel-2 Results: Look for areas with high values in the Geological Spectral Indices tool, where you can find results for iron containing minerals as well as ?clay minerals.
• EMIT Results: Pay close attention to the Spectral Angle Mapper (SAM) results, particularly areas where the spectral angle is smallest. These areas have the highest likelihood of containing the target minerals.

2. Cross-Validation:

• Sentinel-2 vs. EMIT: Compare the results from both datasets. If the hotspots identified by Sentinel-2 align with those from EMIT, it increases the confidence in those areas as targets for further exploration.

3. False Positives:

• Masking Importance: Review the masked areas to ensure that no significant mineralization zones were excluded. Proper masking helps reduce the number of false positives and focuses your attention on the most promising areas.

Ordering Additional Data and Processing

TerraEye is designed to be flexible and scalable, allowing users to expand their analysis as needed.

1. Ordering Additional Datasets:

• Available Datasets: TerraEye offers the ability to order additional datasets such as ASTER, Landsat, Prisma, EnMap, Maxar WorldView-3, Hyperion, and Pixxel?. These datasets can provide complementary data that enhance the accuracy and depth of your analysis.
• How to Order: Within the TerraEye app, navigate to the data order section and select the additional datasets you wish to include. These will be integrated into your project for further analysis.

2. Requesting Additional Processing:

• Advanced Processing Options: TerraEye offers several advanced processing algorithms that can be applied to your AOI, including: Spectral Feature Fitting (SFF): Enhances the identification of specific minerals by fitting known spectral features to the observed data. Siamese Networks: A machine learning approach that improves mineral classification by comparing similar spectral signatures. Linear Spectral Unmixing (LSU): Decomposes mixed pixels into their constituent minerals, providing more detailed insights. Bare Earth Composite (BEC): Uses multiple pictures from long timeseries to find bear Earth pixels
• How to Request: In the TerraEye app, you can request these additional processing options as needed. The app uses a calculation point system, where each additional processing request uses points based on the complexity and data volume.

TerraEye’s robust data processing capabilities, combined with its user-friendly interface, make it an indispensable tool for modern mineral exploration, TerraEye will change your everyday work on geological projects. By leveraging both Sentinel-2 and EMIT data, you can achieve a comprehensive understanding of your AOI, identifying key mineralization zones with confidence.

Whether you are just starting your exploration journey or are looking to refine your analysis with additional data and advanced processing, TerraEye provides the tools you need to succeed. And with the ability to order extra datasets and processing directly within the app, you can continuously expand and improve your exploration efforts.

Explore TerraEye today and unlock the full potential of satellite data for mineral exploration.

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