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Site content related to keyword: "geochemistry"

Geochemical Data of Mafic Rocks in Delaware Piedmont, PA and MD

Geochemical Data of Mafic Rocks in Delaware Piedmont, PA and MD

Geochemical data from Ordovician and Silurian mafic rocks in the Wilmington Complex in Delaware, the James Run Formation in Cecil County, Maryland, and the Wissahickon Formation in Delaware and Pennsylvania were collected in conjunction with preparation of a new geologic map of the Delaware-Pennsylvania Piedmont. Although concentrations of most elements may have been disrupted by metamorphism, the more stable high field strength elements, including the rare earth elements (REE), are consistent within mapped lithodemic units and are compared to modern basaltic magmas from relatively well known tectonomagmatic environments.

Our results are similar to those for other Appalachian mafic rocks and suggest a suprasubduction zone tectonic setting for the Wilmington Complex and the James Run Formation in Cecil County, Maryland. Thus, the rocks of the Wilmington Complex plus the James Run Formation in Cecil County may be stages in a continuum that records the temporal magmatic evolution of an arc complex.

Nanticoke Watershed Water-Quality Database (Data Product No. 05-02)

Nanticoke River

The Nanticoke Watershed Water-Quality Database (NWWWQDB) is used to
store, manage, and retrieve water-quality data generated by the “Nanticoke River
Watershed” project. The database contains information on sampling stations, samples,
and field and laboratory analyses, queries to extract and analyze data, forms to input and
edit data, a main menu to navigate to forms and specific queries, and a few formatted
report templates. The database is in Microsoft Access 2003 format. Table, field, and table
relationship metadata are stored in the database as properties of those objects. The
software's metadata reporting options can be used to view the information.

Delaware Inland Bays Tributary Total Maximum Daily Load Water-Quality Database (Data Product No. 02-02)

Delaware Inland Bays Sampling Locations

The Delaware Inland Bays Water-Quality Database (DIBWQDB) is used to store,
manage, and retrieve water-quality data generated by the “Nutrient Inputs as a Stressor
and Net Nutrient Flux as an Indicator of Stress Response in Delawares’ Inland Bays
Ecosystem” (CISNet) and the “Inland Bays Tributary Total Maximum Daily Load”
(IBTMDL) projects. It contains information on sampling stations, samples, and field and
laboratory analyses, queries to extract and analyze data, forms to input and edit data, a
main menu to navigate to forms and specific queries, and a few formatted report
templates. The database is in Microsoft Access 2003 format. Table, field, and table
relationship metadata are stored in the database as properties of those objects. The
software's metadata reporting options can be used to view the information.

RI74 Locating Ground-Water Discharge Areas in Rehoboth and Indian River Bays and Indian River, Delaware Using Landsat 7 Imagery

RI74 Locating Ground-Water Discharge Areas in Rehoboth and Indian River Bays and Indian River, Delaware Using Landsat 7 Imagery

Delaware’s Inland Bays in southeastern Sussex County are valuable natural resources that have been experiencing environmental degradation since the late 1960s. Stresses on the water resource include land use practices, modifications of surface drainage, ground-water pumping, and wastewater disposal. One of the primary environmental problems in the Inland Bays is nutrient over-enrichment. Nitrogen and phosphorous loads are delivered to the bays by ground water, surface water, and air. Nitrogen loading from ground-water discharge is one of the most difficult to quantify; therefore, locating these discharge areas is a critical step toward mitigating this load to the bays. Landsat 7 imagery was used to identify ground-water discharge areas in Indian River and Rehoboth and Indian River bays in Sussex County, Delaware. Panchromatic, near-infrared, and thermal bands were used to identify ice patterns and temperature differences in the surface water, which are indicative of ground-water discharge. Defining a shoreline specific to each image was critical in order to eliminate areas of the bays that were not representative of open water. Atmospheric correction was not necessary due to low humidity conditions during image acquisition. Ground-water discharge locations were identified on the north shore of Rehoboth Bay (west of the Lewes and Rehoboth Canal), Herring and Guinea creeks, the north shore of Indian River, and the north shore of Indian River Bay near Oak Orchard.

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17

RI60 Geochemistry of the Mafic Rocks, Delaware Piedmont and Adjacent Pennsylvania and Maryland: Confirmation of Arc Affinity

RI60 Geochemistry of the Mafic Rocks, Delaware Piedmont and Adjacent Pennsylvania and Maryland: Confirmation of Arc Affinity

Geochemical data from Ordovician and Silurian mafic rocks in the Wilmington Complex in Delaware, the James Run Formation in Cecil County, Maryland, and the Wissahickon Formation in Delaware and Pennsylvania were collected in conjunction with preparation of a new geologic map of the Delaware-Pennsylvania Piedmont. Although concentrations of most elements may have been disrupted by metamorphism, the more stable high field strength elements, including the rare earth elements (REE), are consistent within mapped lithodemic units and are compared to modern basaltic magmas from relatively well known tectonomagmatic environments.

RI52 Quality and Geochemistry of Ground Water in Southern New Castle County, Delaware

RI52 Quality and Geochemistry of Ground Water in Southern New Castle County, Delaware

Water samples were collected from 63 wells in southern New Castle County to assess the occurrence and distribution of dissolved inorganic chemicals in ground water. Rapid growth is projected for the study area, and suitable sources of potable drinking water will need to be developed. The growth in the study area could also result in degradation of water quality. This report documents water quality during 1991-92 and provides evidence for the major geochemical processes that control the water quality.

RI41 Hydrogeology and Geochemistry of the Unconfined Aquifer, West-Central and Southwestern Delaware

RI41 Hydrogeology and Geochemistry of the Unconfined Aquifer, West-Central and Southwestern Delaware

The unconfined aquifer is the major source of water supply in west-central and southwestern Delaware. The aquifer, which is composed of quartz sand, gravel, clay, and silt, ranges in thickness from 20 to 200 feet. The water table ranges from land surface to about 20 feet below land surface. Analyses of water from wells distributed throughout the area were used to study processes controlling the chemical quality of the water in the unconfined aquifer.

RI40 Sodium Concentrations in Water from the Piney Point Formation, Dover Area, Delaware

RI40 Sodium Concentrations in Water from the Piney Point Formation, Dover Area, Delaware

In the greater Dover area sodium concentrations in ground water from the glauconitic Piney Point Formation commonly exceed 100 parts per million. Investigation of chemical characteristics of the water, and statistical analyses of the results, show that these high concentrations are due to a natural ion-exchange process. Calcium in water replaces sodium in the mineral glauconite and causes the sodium enrichment in ground water.

RI34 Long-Term Chemical-Quality Changes in Selected Delaware Streams

RI34 Long-Term Chemical-Quality Changes in Selected Delaware Streams

Data from three streamflow water-quality stations were statistically analyzed to determine the relationships of the major inorganic chemical constituents to specific conductance and to stream discharge. The results show that ion concentrations varied directly with the flow and with specific conductance. A set of regression equations defining these relationships were derived for each of the three stations: Brandywine Creek at Wilmington, St. Jones River at Dover, and Nanticoke River near Bridgeville.

B10 Salinity of the Delaware Estuary

B10 Salinity of the Delaware Estuary

The purpose of this investigation was to obtain data on and study the factors affecting the salinity of the Delaware River from Philadelphia, Pa., to the Appoquinimink River, Del. The general chemical quality of water in the estuary is described, including changes in salinity in the river cross section and profile, diurnal and seasonal changes, and the effects of rainfall, sea level, and winds on salinity. Relationships are established of the concentrations of chloride and dissolved solids to specific conductance. In addition to chloride profiles and isochlor plots, time series are plotted for salinity or some quantity representing salinity, fresh-water discharge, mean river level, and mean sea level. The two major variables which appear to have the greatest effect on the salinity of the estuary are the fresh-water flow of the river and sea level. The most favorable combination of these variables for salt-water encroachment occurs from August to early October and the least favorable combination occurs between December and May.

RI15 General Ground-Water Quality in Fresh-Water Aquifers of Delaware

RI15 General Ground-Water Quality in Fresh-Water Aquifers of Delaware

Information on ground-water quality in Delaware has become critical for three reasons: (1) increased water demand, (2) need for a better understanding of ground-water flow patterns, (3) need for a "base" against which future quality changes can be measured. Analyses of about 150 water quality samples from wells show that Delaware's fresh ground waters are suitable for most purposes. High iron content may occur, however, in wells tapping the Columbia and the Potomac formations. Overall, total dissolved solids in Delaware aquifers are relatively low except in the Cheswold and Frederica aquifers (Miocene), and possibly parts of the Piney Point Formation (Eocene).

RI13 The Occurrence of Saline Ground Water in Delaware Aquifers

RI13 The Occurrence of Saline Ground Water in Delaware Aquifers

The location of the fresh-salt-water-boundary in the deeper aquifers of Delaware is related mainly to head values. Near coastal areas, dynamic conditions may prevail that affect the interface position within shallow aquifers open to the sea. Holocene and Columbia sands which form Delaware's shallow water-table aquifers contain brackish water in scattered coastal areas while brackish water in the artesian aquifers is found at various depths. Water from Chesapeake Group sediments (Miocene) is fresh in Kent County but is salty in poorly defined areas of Sussex County. The interface in the Piney Point Formation (Eocene) lies just north of Milford and extends in a northeast-southwesterly direction across the State. Brackish water exists in the Magothy and Potomac formations of Cretaceous age a few miles south of Middletown. Heavy pumping near sources of brackish water should be avoided for the present. Proper location of monitoring wells is necessary for detection of future chloride movement.

RI3 Wells for the Observation of Chloride and Water Levels in Aquifers that Cross the Chesapeake and Delaware Canal

RI3 Wells for the Observation of Chloride and Water Levels in Aquifers that Cross the Chesapeake and Delaware Canal

Three test wells were drilled near the banks of the Chesapeake and Delaware Canal, in aquifers formed by sand beds in two geologic units, the nonmarine Cretaceous sediments and the Magothy formation, which crop out along the sides and across the bottom of the canal. The canal carries tidal flow from the Delaware River to and from Chesapeake Bay. The purpose of the wells was to determine whether salt water from the canal has entered the water-bearing beds of these formations, and to determine the head of water in them. It was found that the sands contain fresh water, uncontaminated, and that apparently there was discharge of fresh water from the aquifers to the canal under low head, at least from the winter of late 1955 through early autumn 1957.

DGS Publications

The core of much DGS work culminates in the release of data and findings in official DGS publications, including Open File Reports, Reports of Investigations, Geologic Maps, Hydrologic Maps, and Bulletins.