Overview

Gravity anomalies provide fundamental geophysical information about Earth structure and dynamics. To increase geologic and geodynamic understanding of Alaska, the USGS has collected and processed Alaska gravity data for the past 50 years. This USGS Data Series report introduces and describes an integrated, state-wide gravity database and provides accompanying gravity calculation tools to assist in its application. Additional information includes gravity base station descriptions and digital scans of historical USGS reports. The gravity calculation tools enable the user to reduce new gravity data in a consistent manner for combination with the existing database. This database has sufficient resolution to define the regional gravity anomalies of Alaska. Lack of local isostatic compensation complicates interpretation of regional anomalies in both southern and northern Alaska. However, when filtered appropriately, the Alaska gravity data show regional features with geologic significance. These features include gravity lows caused by low-density rocks of Cenozoic basins, flysch belts, and felsic intrusions, as well as many gravity highs associated with high-density mafic and ultramafic complexes.

This initial release of the integrated Alaska gravity database includes the following components:

A. Report, including historical information, datum description, instructions for use of the gravity reduction tools, and discussion of regional gravity anomalies.
B. Gravity data files
C. Gravity base station descriptions
D. Reference lists for Alaska gravity study reports
E. Historical reports (scanned from original paper copies)
F. Gravity data reduction software tools (based on the Oasis montaj freeware interface)
G. Digital gravity maps

Version 1.0

Posted October 2008