The Problem

The Guyana-Suriname Basin has emerged as one of the world’s most prolific petroleum frontiers, with discoveries like ExxonMobil’s Stabroek Block (“Golden Lane”) holding over 11 billion barrels of recoverable oil.

Yet, a critical question lingers: How did this passive margin, once part of a fragmented supercontinent, become such a rich hydrocarbon haven?

The answer lies buried in the Cretaceous-Paleocene sediments—a geological puzzle complicated by the region’s erosional history and shifting sediment sources.

For decades, the Guiana Shield’s erosional dynamics remained poorly understood.

The presence of a Late Cretaceous peneplanation surface in the inner part of the Guiana Shield, cropping out at elevations above 900 m asl, ascribed to Campanian erosion (~83–72 Ma), suggests vast amounts of sediments were stripped from the shield and delivered to the basin.

However, traditional studies relied on scattered outcrops, leaving gaps in our knowledge of how these ancient sediments traveled—key to understanding the deposits that later became oil reservoirs. Without clarity on sediment pathways, predicting hydrocarbon potential was like searching for treasure without a map.

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The Solution

A groundbreaking study by Roddaz et al. (2021) tackled this challenge by analyzing the geochemistry of clay-sized sediments from the Arapaima-1 well. Their work revealed:

1. Cratonic Dominance: Most sediments originated from the Guiana Shield, with trace elements and Sr-Nd isotopes pointing to erosion of Paleoproterozoic to Mesoproterozoic rocks.
2. Volcanic Inputs: Two samples recorded volcanic activity—likely from the Caribbean Large Igneous Province or the Takutu Rift—adding exotic minerals to the mix.
3. Post-Coniacian Surge: After ~89–86 Ma, increased sediment contributions from the shield’s inner parts suggested uplift and enhanced erosion, possibly driven by mantle upwelling.

These findings confirmed that the Campanian peneplanation surface was a major sediment supplier, funneling material into the basin during a critical period for the present day hydrocarbon fields.

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The Outcome

Today, this research explains why the Guyana-Suriname Basin is an oil giant.

The Cretaceous-Paleocene sediments, derived from the Guyana Shield hinterland, form the main reservoirs of the basin.

The post-Coniacian uplift and erosion—evidenced by the peneplanation surface—delivered thick, still porous sediment stacks that became prime reservoirs.

For Industry & Science:

• Exploration: Target areas with similar geochemical signatures (e.g., near paleo-river mouths).
• Climate Clues: Sediment burial patterns help model ancient carbon cycles.
• Global Analogues: These processes likely shaped other Atlantic margins (e.g., West Africa’s conjugate basins).

The “Golden Lane” is no accident—it’s the product of 100 million years of erosion, volcanism, and tectonic shifts.

By decoding this past, science has not only explained today’s bonanza but also lit the path for future discoveries.

Full Credit:

Provenance constraints on the Cretaceous-Paleocene erosional history of the Guiana Shield as determined from the geochemistry of clay-size fraction of sediments from the Arapaima-1 well (Guyana-Suriname basin.

Martin Roddaz et. al.,

Marine Geology, Volume 434, April 2021, 106433.