Interval (Chrono/Lithostratigraphy and Biozone): Add/Edit dialogs

Samples

Select the Top and Base Sample which define the interval by pressing the ellipsis (...) buttons to the right of the Sample fields to open the Sample: Select dialog.

Note: The values in both depth fields default to the sample or samples selected on the Samples tab. The quickest way to enter intervals is to open the scheme in the Stratigraphic schemes tab, select the bounding samples on the samples tab, and double-click the unit in the scheme diagram.

Note: In StrataBugs, intervals are defined by the upper and lowermost samples which indicate membership of a particular stratigraphic unit. Commonly, the boundary between successive units lies between samples, thus the top sample of one interval is not necessarily the base sample of the overlying interval. This creates a gap between the samples. Where boundaries are not based on a physical sample but, for example, on a pick from a wireline log, you must create LOG type samples to indicate the picked depths. For Biozones, boundaries will almost always be based on CU, SC, CO or OC samples. For Lithostratigraphic intervals the bounding depths are most likely to be LOG samples. For Chronostratigraphy the sample type will depend on whether ages are based purely on biostratigraphic samples or drawn to the nearest lithostratigraphic boundary.

Boundaries

Select a type for the Top and Base Boundaries by making a selection from the drop down lists attached to the Boundary fields. The options are Confident, Probable, Possible, Unconformable, ?Unconformable, Fault, ?Fault or Reverse fault

Note: The boundary type is illustrated on charts by different line styles, and forms the basis of the style of correlations lines which inherit the style from intervals through which they pass.

Note: If you have samples selected (or subsequently select them) the boundary types default to the boundary types already recorded at those samples. If there are no samples, or no other interval boundaries at those samples, the default type is confident. Intervals sharing a boundary sample (i.e. sample defines top of one and base of next) must use the same boundary type. If you change the boundary type, all other intervals using this boundary will be updated (you will NOT be warned about this).
Spot intervals (where the top and base samples are the same) are allowed to have different boundary types. In this scenario, other intervals' boundaries will NOT be updated. A spot interval's boundary types are only updated during changes to other intervals if its boundary types are equal.

Analyst

To show who made the interpretation of each boundary select an Analyst from the drop down lists attached to the Analyst fields. These will display all the analysts who have contributed data to the current well. The analyst selection is only enabled for Biozone intervals, since the biostratigraphy may be determined by the sample analyses. If there are no analytical data for the well, you will need to select the analyst from the list of all the analysts in the database. To do this press the ellipsis (...) buttons to the right of the Analyst fields and select an analyst from the list in the Select Analyst dialog.

Scheme

Select a Stratigraphic Scheme from the drop down list attached to the Scheme field. Every interval MUST be linked to a scheme name (unlike in previous versions of StrataBugs). For biozone intervals, you may have data for more than one scheme which covers the same depth interval. For chronostratigraphic and lithostratigraphic intervals, you must not have any overlapping intervals within any version, regardless of scheme.

Unit names

Select the Upper unit name for this interval by pressing the ellipsis (...) button to the right of the Upper unit name field. A list of units from the selected scheme are displayed in the Select Unit dialog.

The Lower unit name field is used to indicate that the selected interval spans more than one stratigraphic unit, and that the boundaries between them cannot be identified (e.g. Paleocene - Eocene). Repeat the process described above ensuring that the oldest unit is always in this field. If there is no lower unit name leave this field blank.

Use the check boxes adjacent to the Upper/Lower unit name fields to prefix the unit name with a "?" if required.

Hint: You may edit the interval name (e.g. Lower to Lowest) whilst the formal name on which the interval is based remains the same. This enables some degree of qualification of the interval name whilst allowing the interval to be correlated on charts with other well intervals based on the same formal stratigraphic units from the same scheme. The original Formal name is displayed underneath the Upper/Lower unit name fields.

Note: Upper and Lower units must belong to the same scheme.

Note: StrataBugs will check for depth conflicts and will not let you enter overlapping data items.

The Separator will automatically display between the two unit names. By default the separator is a '-' but you can edit it to any string up to ten characters in length.

Note that characters used do have implications and you should try to use them consistently throughout your database. For example, '-' implies the interval goes FROM the upper unit TO the lower unit, while '/' implies that the interval could represent EITHER the upper OR the lower unit.

The Level field will automatically display the hierarchical level of the selected units. If you have not selected a unit from a scheme and wish only to type in an informal term you must then select the desired level from the drop down list attached to the Level field.

Note: upper and lower units are allowed to be from different hierarchical levels in the scheme. If it does not set automatically, you should set the level to the lowest of the two units' levels. Generally we recommend that interval units be from the same scheme levels.