A constrained 2D gravity model of the Sebastián Vizcaíno Basin, Baja California Sur, Mexico

The subsurface geometry of the Sebastián Vizcaíno Basin is obtained from the 2D inversion of gravity data, constrained by a density-versus-depth relationship derived from an oil exploration deep hole. The basin accumulated a thick pile of marine sediments that evolved in the fore-arc region of the compressive margin prevalent along western North America during Mesozoic and Tertiary times. Our interpretation indicates that the sedimentary infill in the Sebastián Vizcaíno Basin reaches a maximum thickness of about 4 km at the centre of a relatively symmetric basin. At the location of the Suaro-1 hole, the depth to the basement derived from this work agrees with the drilled interface between calcareous and volcaniclastic members of the Alisitos Formation. A sensitivity analysis strongly suggests that the assumed density function leads to a nearly unique solution of the inverse problem.     

Karst database development in Minnesota: design and data assembly

The Karst Feature Database (KFD) of Minnesota is a relational GIS-based Database Management System (DBMS). Previous karst feature datasets used inconsistent attributes to describe karst features in different areas of Minnesota. Existing metadata were modified and standardized to represent a comprehensive metadata for all the karst features in Minnesota. Microsoft Access 2000 and ArcView 3.2 were used to develop this working database. Existing county and sub-county karst feature datasets have been assembled into the KFD, which is capable of visualizing and analyzing the entire data set. By November 17 2002, 11,682 karst features were stored in the KFD of Minnesota. Data tables are stored in a Microsoft Access 2000 DBMS and linked to corresponding ArcView applications. The current KFD of Minnesota has been moved from a Windows NT server to a Windows 2000 Citrix server accessible to researchers and planners through networked interfaces.     

Rare earth elements in the clay fraction of coaliferous sediments of the Arkagalinskoe (Magadan district) and Dolinskoe (Sakhalin Island) coalfields

The study of REE distribution in the clay fraction of sedimentary rocks from two coalfields made it possible to distinguish several types of REE distribution, which correlate with their mineral composition. It is shown that the REE fractionation was related to the mineral reconstruction of the primary clay fraction and some detrital minerals in the course of postsedimentary transformations of rocks during diagenesis, early catagenesis, and beginning of late catagenesis. These transformations were governed by several factors, such as the composition of sediments; hydrochemical features of accumulation environment; the chemical composition, dynamics, and feeding sources of pore solutions; the porosity and permeability of sediments and rocks; and the content of organic matter and its reaction ability.