Stratigraphy Picture

[Sourabh Doherty]

Iam a geology student and I'm working on my bachelor thesis. I need to make few models and a map in rockworks but unfortunately I have a problems which I can not solve on my own and I can't find anybody capable of helping me.

The thing is I am modeling a part of a structure and it's subsoil in the Czech Republic. The main problem in the model is (you can see it on the picture bellow) stratigraphy. For some reason the proterozoic era goes through cretaceous and whole paleozoic is also messed up... The stratigraphy is in czech langue so I will translate for you:

2nd problem is with 2d map. I need to create a 2d map with topography and litology but I can't manage to create it. I don't know If I am doing it right, but there are no topography lines and only few litilogy. 3rd picture bellow. My guess is it only takes a certain level of topography.

Hi, thanks for the answer. The numbers in the stratigraphy table should be good cretaceous is lowest, paleozoic is middle and proterozoic has the highest value. I don't fully understand the grid thing. What do you mean by control points?

Hey thanks for the tip. I've checked the litology datasheet in all boreholes and triple checked stratigraphy datasheet and it looks fine so my guess is problem is somewhere else. I've also checked again the values in datasheet and lowered the value of "unknown age" so proterozoic would be last but I don't use boreholes with these since they are not needed for the model.

RockWorks 16 and 17 both have the option to allow underlying units take precedence when grids intersect when creating a Stratigraphy model. In RockWorks 16, this option is called Onlap and is set from the Stratigraphy model menu under the Interpolate Surfaces item.

In either case, the automatic Stratigraphy modeling may not produce the model you wish, especially if control is sparse for the lower units. In that case, you can build your model manually using additional control points created from the thicknesses of each unit in the Utilities datasheet, and Utilities Grid Math to subtract the thickness from the top unit to get the top of the underlying unit.

You are welcome to create a backup of the project with the Borehole Manager File Backup Database menu command and send the ZIP file to sup...@rockware.com. Include your RwGrd files in the ZIP file. Larger files may be uploaded to rockware.com/upload or you may send a link to your DropBox, Google Drive, or other shared folder.

I tired the onlap function many times. On the 1st picture is onlap turned on and 2nd is onlap off. It only removes paleozoic under proterozoic but still leaves proterozoic in the middle of cretaceous.

I've tried to downloaad the trial version of Rockworks 17 but for some reason the converting from 16 to 17 maded errors and even after fixing it the files are not suitable I guess because when I want to create model or something else everything is so small and unreadable and the model is not even showing.

So I shloud try to create new unreal boreholes to fix it? I've also tried adding 0 thickness of proterozoic under paleozoic and 0 thickness to paleozoic where is proterozoic right under the cretaceous but it still did not help.

The backup file is pretty small so it should be no problem. Only the stratigraphy and litology datasheets are in czech language so I hope I won't be a big problem or you can use google translator If needed. Here are the most common rocks: cretaceous slnovec = marlstone; pskovec = sandstone, psek = sand; slepenec = conglomerate; jl = clay, jlovec = claystone and some older proterozoic slates = břidlice.

Lower strata are older than those lying on top of them.Principle of Superposition: In an otherwise undisturbed sequence of sedimentary strata, or rock layers, the layers on the bottom are the oldest, and the layers above them are younger.

Principle of Original Horizontality: Layers of rocks deposited from above, such as sediments and lava flows, are originally laid down horizontally. The exception to this principle is at the margins of basins, where the strata can slope slightly downward into the basin.

Principle of Lateral Continuity: Within the depositional basin, strata are continuous in all directions until they thin out at the edge of that basin. Of course, all strata eventually end, either by hitting a geographic barrier, such as a ridge, or when the depositional process extends too far from its source, either a sediment source or a volcano. Strata that are cut by a canyon later remain continuous on either side of the canyon.

Dark dike cutting across older rocks, the lighter of which is younger than the grey rock.Principle of Cross-Cutting Relationships: Deformation events like folds, faults and igneous intrusions that cut across rocks are younger than the rocks they cut across.

Principle of Fossil Succession: Evolution has produced a succession of unique fossils that correlate to the units of the geologic time scale. Assemblages of fossils contained in strata are unique to the time they lived and can be used to correlate rocks of the same age across a wide geographic distribution. Assemblages of fossils refer to groups of several unique fossils occurring together.

The Grand Canyon of Arizona illustrates the stratigraphic principles. The photo shows layers of rock on top of one another in order, from the oldest at the bottom to the youngest at the top, based on the principle of superposition. The predominant white layer just below the canyon rim is the Coconino Sandstone. This layer is laterally continuous, even though the intervening canyon separates its outcrops. The rock layers exhibit the principle of lateral continuity, as they are found on both sides of the Grand Canyon which has been carved by the Colorado River.

There are three types of unconformities, nonconformity, disconformity, and angular unconformity. A nonconformity occurs when sedimentary rock is deposited on top of igneous and metamorphic rocks as is the case with the contact between the strata and basement rocks at the bottom of the Grand Canyon.

The strata in the Grand Canyon represent alternating marine transgressions and regressions where sea level rose and fell over millions of years. When the sea level was high marine strata formed. When sea-level fell, the land was exposed to erosion creating an unconformity. In the Grand Canyon cross-section, this erosion is shown as heavy wavy lines between the various numbered strata. This is a type of unconformity called a disconformity, where either non-deposition or erosion took place. In other words, layers of rock that could have been present, are absent. The time that could have been represented by such layers is instead represented by the disconformity. Disconformities are unconformities that occur between parallel layers of strata indicating either a period of no deposition or erosion.

In the lower part of the picture is an angular unconformity in the Grand Canyon known as the Great Unconformity. Notice flat-lying strata over dipping strata (Source: Doug Dolde).The Phanerozoic strata in most of the Grand Canyon are horizontal. However, near the bottom horizontal strata overlie tilted strata. This is known as the Great Unconformity and is an example of an angular unconformity. The lower strata were tilted by tectonic processes that disturbed their original horizontality and caused the strata to be eroded. Later, horizontal strata were deposited on top of the tilted strata creating the angular unconformity.

Angular unconformity, where sedimentary strata are deposited on a terrain developed on sedimentary strata that have been deformed by tilting, folding, and/or faulting. so that they are no longer horizontal.

Block diagram to apply relative dating principles. The wavy rock is a old metamorphic gneiss, A and F are faults, B is an igneous granite, D is a basaltic dike, and C and E are sedimentary strata.In the block diagram, the sequence of geological events can be determined by using the relative-dating principles and known properties of igneous, sedimentary, and metamorphic rock (see Chapter 4, Chapter 5, and Chapter 6). The sequence begins with the folded metamorphic gneiss on the bottom. Next, the gneiss is cut and displaced by the fault labeled A. Both the gneiss and fault A are cut by the igneous granitic intrusion called batholith B; its irregular outline suggests it is an igneous granitic intrusion emplaced as magma into the gneiss. Since batholith B cuts both the gneiss and fault A, batholith B is younger than the other two rock formations. Next, the gneiss, fault A, and batholith B were eroded forming a nonconformity as shown with the wavy line. This unconformity was actually an ancient landscape surface on which sedimentary rock C was subsequently deposited perhaps by a marine transgression. Next, igneous basaltic dike D cut through all rocks except sedimentary rock E. This shows that there is a disconformity between sedimentary rocks C and E. The top of dike D is level with the top of layer C, which establishes that erosion flattened the landscape prior to the deposition of layer E, creating a disconformity between rocks D and E. Fault F cuts across all of the older rocks B, C and E, producing a fault scarp, which is the low ridge on the upper-left side of the diagram. The final events affecting this area are current erosion processes working on the land surface, rounding off the edge of the fault scarp, and producing the modern landscape at the top of the diagram.

All elements on the Periodic Table of Elements (see Chapter 3) contain isotopes. An isotope is an atom of an element with a different number of neutrons. For example, hydrogen (H) always has 1 proton in its nucleus (the atomic number), but the number of neutrons can vary among the isotopes (0, 1, 2). Recall that the number of neutrons added to the atomic number gives the atomic mass. When hydrogen has 1 proton and 0 neutrons it is sometimes called protium (1H), when hydrogen has 1 proton and 1 neutron it is called deuterium (2H), and when hydrogen has 1 proton and 2 neutrons it is called tritium (3H).

3a8082e126