Geology of the Spearhead Mountain Stock, Sheldon Lake Map sheet, Yukon Territory

A two square mile stock of biotite quartz monzonite forms the core of Spearhead Mountain. The stock has intruded Ordovician and Silurian sediments and has thermalIy altered them for a distance of up to one quarter mile. Mineralizing fluids ascended near vertical cooling fractures in the quartz monzonite, creating a porphyry copper deposit of chalcopyrite and pyrrhotite.

Trend surfaces from the first to the third order were established from plagioclase, orthoclase, quartz and total mafic minerals modal data and specific gravity values for the intrusive rock. Quartz, total mafic minerals and specific gravity vary systematically while orthoclase and plagioclase have erratic distributions. Contoured modal data and second degree trend surfaces for quartz, specific gravity and total mafic minerals show a circular distribution pattern. Linear trend surfaces indicate northwesterly and southeasterly gradients for quartz, plagioclase, orthoclase and specific gravity.

The original homogeneous granitic magma was contaminated by silica assimilation of the intruded, highly siliceous sediments. Incomplete diffusion of the contaminating silica Iead to a circular outward increase in silica and a corresponding outward decrease in mafic minerals, but did not significantly affect the distribution of orthoclase or plagioclase. The circular zonation of the high specific gravity mafic minerals gave rise to a similar zonation of specific gravities.

This thesis is available online at http://data.geology.gov.yk.ca/Reference/68112. A copy of this thesis is available at the EMR library – QE195 S26.

Datasets available for download

• Yukon Geological Survey publication metadataHTML
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• Science and Technology
• ygs-import
• ygs-import-20250711
• ygs-publications
• yukon-geological-survey

Additional Info

• Maturity Level 1 (46%)
• Maturity Level 2 (38%)
• Maturity Level 3 (0%)
• Maturity Level 4 (0%)
• Maturity Level 5 (0%)
• Maturity Level 6 (0%)

Field	Value
Last Updated	October 20, 2025, 02:20 (UTC)
Created	October 20, 2025, 02:20 (UTC)
Domain / Topic Domain or topic of the dataset being cataloged.
Title Title for the Dataset.	Geology of the Spearhead Mountain Stock, Sheldon Lake Map sheet, Yukon Territory
Description A description of the dataset.	A two square mile stock of biotite quartz monzonite forms the core of Spearhead Mountain. The stock has intruded Ordovician and Silurian sediments and has thermalIy altered them for a distance of up to one quarter mile. Mineralizing fluids ascended near vertical cooling fractures in the quartz monzonite, creating a porphyry copper deposit of chalcopyrite and pyrrhotite. Trend surfaces from the first to the third order were established from plagioclase, orthoclase, quartz and total mafic minerals modal data and specific gravity values for the intrusive rock. Quartz, total mafic minerals and specific gravity vary systematically while orthoclase and plagioclase have erratic distributions. Contoured modal data and second degree trend surfaces for quartz, specific gravity and total mafic minerals show a circular distribution pattern. Linear trend surfaces indicate northwesterly and southeasterly gradients for quartz, plagioclase, orthoclase and specific gravity. The original homogeneous granitic magma was contaminated by silica assimilation of the intruded, highly siliceous sediments. Incomplete diffusion of the contaminating silica Iead to a circular outward increase in silica and a corresponding outward decrease in mafic minerals, but did not significantly affect the distribution of orthoclase or plagioclase. The circular zonation of the high specific gravity mafic minerals gave rise to a similar zonation of specific gravities. This thesis is available online at http://data.geology.gov.yk.ca/Reference/68112. A copy of this thesis is available at the EMR library – QE195 S26.
Tags / Keywords Keywords/tags categorizing the dataset.	Science and Technology ygs-import ygs-import-20250711 ygs-publications yukon-geological-survey
Format (CSV, XLS, TXT, PDF, etc) File format of the dataset.
Dataset Size Dataset size in megabytes.
Metadata Identifier Metadata identifier – can be used as the unique identifier for catalogue entry
Published Date Published date of the dataset.	2011-04-04
Time Period Data Span (start date) Start date of the data in the dataset.
Time Period Data Span (end date) End date of time data in the dataset.
GeoSpatial Area Data Span A spatial region or named place the dataset covers.

Field	Value
Access category Type of access granted for the dataset (open, closed, service, etc).
License License used to access the dataset.	Open Government Licence - Yukon
Limits on use Limits on use of data.
Location Location of the dataset.	https://open.canada.ca/data/en/dataset/b67dffc8-6963-4aee-b8c3-d79c572ff2bb
Data Service Data service for accessing a dataset.
Owner Owner of the dataset.	Government of Yukon | Gouvernement du Yukon
Contact Point Who to contact regarding access?	Yukon Geological Survey
Contact Point Email The email to contact regarding access?
Publisher Publisher of the dataset.
Publisher Email Email of the publisher.	[email protected]
Author Author of the dataset.
Author Email Email of the author.
Accessed At Date the data and metadata was accessed.

Field	Value
Identifier Unique identifier for the dataset.
Language Language(s) of the dataset
Link to dataset description A URL to an external document describing the dataset.
Persistent Identifier Data is identified by a persistent identifier.
Globally Unique Identifier Data is identified by a persistent and globally unique identifier.
Contains data about individuals Does the data hold data about individuals?
Contains data about identifiable individuals Does the data hold identifiable data about individual?
Contains Indigenous Data Does the data hold data about Indigenous communities?
Portal Type Platform type of the source portal.

Field	Value
Version Version of the datatset	None
Source Source of the dataset.	None
Version notes Version notes about the dataset.
Is version of another dataset Link to dataset that it is a version of.
Other versions Link to datasets that are versions of it.
Provenance Text Provenance Text of the data.
Provenance URL Provenance URL of the data.
Temporal resolution Describes how granular the date/time data in the dataset is.
GeoSpatial resolution in meters Describes how granular (in meters) geospatial data is in the dataset.
GeoSpatial resolution (in regions) Describes how granular (in regions) geospatial data is in the dataset.

Field	Value
Indigenous Community Permission Who holds the Indigenous Community Permission. Who to contact regarding access to a dataset that has data about Indigenous communities.
Community Permission Community permission (who gave permission).
The Indigenous communities the dataset is about Indigenous communities from which data is derived.

Field	Value
Number of data rows If tabular dataset, total number of rows.
Number of data columns If tabular dataset, total number of unique columns.
Number of data cells If tabular dataset, total number of cells with data.
Number of data relations If RDF dataset, total number of triples.
Number of entities If RDF dataset, total number of entities.
Number of data properties If RDF dataset, total number of unique properties used by the triples.
Data quality Describes the quality of the data in the dataset.
Metric for data quality A metric used to measure the quality of the data, such as missing values or invalid formats.

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