The Persian Gulf region repeatedly appears in global news — whether due to the Iran–Israel conflict, rising tensions around the Strait of Hormuz, or concerns about disruptions in global oil supply. For UPSC aspirants, a deeper understanding of why the Persian Gulf holds over 50 percent of the world’s proven oil reserves is essential.

The real explanation lies in geology, paleogeography, and the evolution of the ancient Tethys Sea.

1. Fossil Fuels: Why Marine Life Matters

UPSC often tests the fundamentals:
Oil and natural gas are formed from marine organisms, buried under sediment, compressed over millions of years, and transformed into hydrocarbons.

Just like coal forms from forests, oil forms from marine sedimentation + heat + pressure.

So, wherever ancient oceans once existed and accumulated rich marine deposits, today’s oil fields are found.

2. The Tethys Sea: The Ancient Ocean Behind Persian Gulf Oil

The Persian Gulf is a surviving remnant of the ancient Tethys Sea.

Why this matters:

• Tethys was a warm, nutrient-rich, elongated ocean between
  • Laurasia (Angara land) in the north
  • Gondwana land in the south
• Its shrinkage due to continental collision created:
  • the Himalayas
  • mountains of Europe and West Asia
  • massive marine sediment basins

These basins contain thick layers of compressed organic matter, making the Persian Gulf one of the world’s richest petroleum zones.

3. Perfect Conditions for Oil Formation in the Persian Gulf

The region provided all four essential ingredients for large-scale oil creation:

1. Warm climate (Cretaceous period)

Ideal for marine biodiversity → massive organic accumulation.

2. Volcanic fertilisation

Volcanism released nitrates, sulfates, and minerals → boosting ocean productivity.

3. Slow subsidence + sedimentation

Marine remains were buried for millions of years.

4. Tethys Sea compression

The collision of plates squeezed and transformed the sediments → creating hydrocarbons.

This is why modern countries like Iran, Iraq, Kuwait, Bahrain, Qatar, UAE, and Saudi Arabia sit atop huge oil fields.

4. Major Oil Fields in the Persian Gulf (Important for UPSC Prelims)

Some of the world’s top oil fields lie here:

• Ghawar Field (Saudi Arabia) – world’s largest
• Safaniya Field (Saudi Arabia) – world’s largest offshore field
• Burgan Field (Kuwait)
• Ahvaz Field (Iran)
• Upper Zakum (UAE)
• Marjan Complex (Saudi Arabia)

All are direct outcomes of Tethys Sea sedimentation.

5. Why the Red Sea Does NOT Have Similar Oil Reserves

UPSC loves this comparative angle.

The Red Sea did NOT form from Tethys compression.

Instead:

• It is a new ocean basin, created when the Arabian Plate rifted away from Africa.
• It lacks the ancient organic-rich marine sediments needed for major oil reserves.

That’s why Persian Gulf = abundant oil,
but Red Sea = negligible oil.

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FAQs

• #PersianGulfOilReservesUPSC: Why does the Persian Gulf hold such a high percentage of global oil reserves?
• #TethysSeaUPSC: How did the Tethys Sea influence the geology and oil formation of the Persian Gulf?
• #StraitOfHormuzUPSC: Why is the closure of the Strait of Hormuz critical for global oil trade and India?
• #WestAsiaGeographyUPSC: What geological factors explain the difference in oil presence between the Persian Gulf and the Red Sea?