Geochemical, Modal, and Geochronologic Data for 1.4 Ga A-type Granitoid
Intrusions of the Conterminous United States

By Edward A. du Bray, Christopher S. Holm-Denoma, Carma A. San Juan,
Karen Lund, W.R. Premo, and Ed DeWitt

2015

Data Series 942

ABSTRACT

These polygons portray the spatial distribution of 1.4 Ga A-type granitoid
intrusions in the conterminous United States. In general, North American
A-type granites are iron-enriched granitoids occurring in anorogenic,
continental settings, the majority of which were emplaced between 1.5 and
1.4 Ga. The relations between A-type granitoid rocks, tectonic setting,
and magma petrogenesis, as well as genetic associations with important
types of ore deposits are well established. This geospatial database
containing geologic, geochemical, modal, and geochronologic information
for A-type granitoid rocks in the conterminous United States was developed
to support ongoing investigations.

These points portray the spatial distribution of geochemical samples
associated with 1.4 Ga A-type granitoid intrusions in the conterminous
United States. In general, North American A-type granites are iron-enriched
granitoids occurring in anorogenic, continental settings, the majority of
which were emplaced between 1.5 and 1.4 Ga. The relations between A-type
granitoid rocks, tectonic setting, and magma petrogenesis, as well as
genetic associations with important types of ore deposits are well
established. Thus, this geospatial database was developed to compile
geologic, geochemical, modal, and geochronologic information for A-type
granitoid rocks to support ongoing investigations.

These points portray the spatial distribution of geochronological samples
associated with 1.4 Ga A-type granitoid intrusions in the conterminous
United States. In general, North American A-type granites are iron-enriched
granitoids occurring in anorogenic, continental settings, the majority of
which were emplaced between 1.5 and 1.4 Ga. The relations between A-type
granitoid rocks, tectonic setting, and magma petrogenesis, as well as
genetic associations with important types of ore deposits are well
established. Thus, this geospatial database was developed to compile
geologic, geochemical, modal, and geochronologic information for A-type
granitoid rocks to support ongoing investigations.

DISCLAIMERS

Any use of trade, product or firm names is for descriptive purposes
only and does not imply endorsement by the U.S. Government.

Although this information product, for the most part, is in the public
domain, it also contains copyrighted material as noted in the text.
Permission to reproduce copyrighted items for other than personal use
must be secured from the copyright owner.

This database, identified as DS 942, has been approved for release
and publication by the U.S. Geological Survey (USGS).  Although this
database has been subjected to rigorous review and is substantially
complete,the USGS reserves the right to revise the data pursuant to
further analysis and review. Furthermore, it is released on condition
that neither the USGS nor the U.S. Government may be held liable
for any damages resulting from its authorized or unauthorized use.

Although these data have been processed successfully on a computer
system at the U.S. Geological Survey (USGS), no warranty, expressed or
implied is made regarding the display or utility of the data on any
other system, or for general or scientific purposes, nor shall the act
of distribution constitute such warranty.  The USGS or the U.S
Government shall not be held liable for improper or incorrect use of
the data described and/or contained herein.

DATA FILES

List of files:
00ReadMe.txt
ds942.pdf
ds942_plate1.pdf

metadata files
	IntrsAType1_4Ga_FGDC.xml
	IntrsChemModal_FGDC.xml
	IntrsGeochron_FGDC.xml	

Datafiles directory 
              
	ds942_US_14Intrusion.gdb.zip directory
		IntersAType1_4Ga
		IntersChemModal
		IntersGeochron
					
       ds942_shapefiles.zip directory:
		IntrsAType1_4Ga.shp (.cpg/dbf/prj/sbn/sbx/shp.xml/shx)	
		IntrsChemModal.shp (.cpg/dbf/prj/sbn/sbx/shp.xml/shx)
		IntrsGeochron.shp (.cpg/dbf/prj/sbn/sbx/shp.xml/shx)

HOW TO OBTAIN THE DIGITAL FILES

The digital files constituting the geologic map database of this
report can be obtained via the Internet from the U.S. Geological 
Survey publications website. Go to the web page at
http://pubs.er.usgs.gov/publication/ds942 or http://dx.doi.org/10.3133/ds942
and follow the directions to download the files.

The main product is a Portable Document Format (.pdf) map, which
requires Adobe Acrobat for viewing, and from which paper copies may be
printed.  Acrobat software runs on a variety of systems, and is
available for download free of charge from Adobe at
http://www.adobe.com.

ArcReader may be downloaded free of charge from
http://www.esri.com/software/arcgis/arcreader/download.htm for viewing
additional files included in this report.