Geology Expert

---
name: geology-expert
version: 1.0.0
description: Expert-level geology covering plate tectonics, rock cycle, mineralogy, stratigraphy, geomorphology, structural geology, and economic geology.
author: luo-kai
tags: [geology, plate tectonics, rocks, minerals, stratigraphy]
---

# Geology Expert

## Before Starting
1. Which subdiscipline? (structural, sedimentary, igneous, metamorphic, economic)
2. Field mapping or laboratory analysis?
3. Academic or applied context?

## Core Expertise Areas

### Plate Tectonics
Lithospheric plates: rigid segments of crust and upper mantle.
Divergent boundaries: plates move apart, new oceanic crust forms, rift valleys.
Convergent boundaries: subduction zones, mountain building, volcanism.
Transform boundaries: plates slide past each other, strike-slip faults.
Driving mechanisms: mantle convection, ridge push, slab pull.

### Rock Cycle
Igneous: crystallized from magma or lava — intrusive (slow, coarse) or extrusive (fast, fine).
Sedimentary: lithified sediments — clastic, chemical, biochemical.
Metamorphic: existing rock transformed by heat and pressure — foliated or non-foliated.
Rock cycle: rocks transform between types through geological processes.

### Mineralogy
Mineral identification: hardness (Mohs), cleavage, fracture, luster, color, streak.
Silicate minerals: most common — quartz, feldspar, mica, pyroxene, olivine.
Non-silicates: carbonates, oxides, sulfides, halides, phosphates.
Crystal systems: cubic, tetragonal, orthorhombic, hexagonal, monoclinic, triclinic.

### Stratigraphy
Law of superposition: younger layers above older in undisturbed sequences.
Relative dating: cross-cutting relationships, unconformities, fossil zones.
Absolute dating: radiometric methods — U-Pb, K-Ar, Rb-Sr, C-14 for young material.
Stratigraphic correlation: matching rock units across areas using index fossils.

### Structural Geology
Stress and strain: compressive, tensile, shear stress producing folds and faults.
Faults: normal (extension), reverse (compression), strike-slip (shear).
Folds: anticlines and synclines from compressional stress.
Stereonet: plot structural data — strike, dip, lineations, fold axes.

## Best Practices
- Always record strike and dip measurements with consistent convention
- Document field observations before interpretation
- Use multiple dating methods to cross-validate ages
- Consider original depositional environment when interpreting rocks

## Common Pitfalls
| Pitfall | Fix |
|---|---|
| Confusing rock and mineral | Rocks are aggregates of minerals |
| Ignoring unconformities | They represent missing time in the record |
| Wrong fault sense of motion | Use offset markers to determine direction |
| Contamination in radiometric dating | Use isochron methods to detect open-system behavior |

## Related Skills
- geophysics-expert
- earth-sciences/seismology-expert
- earth-sciences/hydrology-expert