Unconformity

types of unconformity

1. GOVT. MODEL SCIENCE COLLEGE (auto) session :- 2016-2017 Topic :- Types of UNCONFORMITY SUBMITTED TO :- SUBMITTED BY:- Dr. Sanjay Tignath sir Mayank Mahawar M.Sc. 1 ST SEM ROLL NO:-12

2. Unconformity :- An unconformity is a depositional contact between two rocks of measurably ages. An unconformity is a surface of erosion that separates the younger strata from older rocks. It is one of the most common geological feature found in rocks or in succession . Unconformities represent gaps in the geologic record; periods of time that are not represented by any rocks. Unconformities are resulted due to tectonic activity in form of uplift or subsidence of land .

3. Unconformity AA’ is b/w the Miocene and P ilocene ( miocene was folded and faulted).Unconformity BB’ is b/w the P ilocene and pleistocene .

4. Types of unconformity :- Angular unconformity Non conformity Disconformity Local unconformity

5. An angular unconformity is an erosional surface and separates an older sequence of rocks, in which bedding is inclined to the unconformity, from a younger sequence in which bedding is essentially parallel to the unconformity. The term “angular” expresses the fact that layers above and below angular unconformities are not parallel . ANGULAR UNCONFORMITY :-

6. EXAMPLE OF ANGULAR UNCONFORMITY :- Angular Unconformity : San Lorenzo Canyon area,

7. NON-CONFORMITY :- Non conformity are depositonal surface which separating younger sedimentary or volcanic rocks from underlying older crystalline rocks(metamorphic rock or igneous rock). They usually indicate that a long period of erosion occurred prior to deposition of the sediments

8. Example of Non conformity Grand Canyon,Arizona ; sandstone ( cambrian ) overlies schist (Proterozoic )

9. DISCONFORMITY :- It is also known as parallel unconformity. A disconformity separates two sequences, both of which are bedded parallel to the unconformity.

10. Example of Disconformity :- Kane County, Utah , United States

11. Local Unconformity :- Also known as non-depositional unconformity. It is similar to a disconformity but local in extent and represents a short period of non-deposition. The age difference between the overlying and underlying beds is very less. This is generally found in flood affected areas representing short time gaps.

12. Recognition of unconformity :- Difference in structure Difference observation Difference in fossil record Presence of conglomarate Difference in environmental of deposition

13. Reference :- An outline of structural geology –PAUL F. WILLIAMS Structural Geology – M.P. BILLINGS Structural Geology of rocks and regions – GEORGE H. DAVIS