Titan's atmosphere is rich in methane (CH_4), which is constantly destroyed by sunlight. S… — ACT

Titan's atmosphere is rich in methane ( $CH_4$ ), which is constantly destroyed by sunlight. Scientists propose different models to explain how it is replenished.

Model 1 (Episodic Cryovolcanism)
Methane is stored in methane clathrate hydrates within Titan's icy crust. This methane was incorporated during Titan's formation. Heat plumes from Titan's core periodically rise through the mantle, causing localized melting of the crust. This triggers episodic cryovolcanic eruptions that release large pulses of methane into the atmosphere. Replenishment is not constant; it occurs in brief, intense bursts separated by hundreds of millions of years.

Model 2 (Deep Serpentinization)
Methane is continuously produced in Titan's rocky core. Liquid water, circulating through the warm silicate core, reacts with olivine minerals in a process called serpentinization. This reaction produces hydrogen ( $H_2$ ), which then reacts with carbon dioxide ( $CO_2$ ) to synthesize new methane. This newly created methane continuously ascends through the liquid water ocean and the icy crust, escaping into the atmosphere via steady diffusion through tectonic fractures.

Model 3 (Tidal Sublimation)
Titan accreted a vast reservoir of methane ice directly into its outer crust during formation. No new methane is currently being produced. Instead, gravitational interactions with Saturn generate tidal forces that flex Titan's crust. This tidal heating is concentrated in the crust, causing solid methane ice to sublimate (change directly from solid to gas). The gas escapes through porous ice, providing a steady, gradually declining release of primordial methane into the atmosphere.

Match each model of Titan's methane replenishment to the statement that best represents its hypothesis regarding the origin and release mechanism of the methane.

Model 1Primordial methane stored in crustal clathrates is released during episodic volcanic events driven by mantle plumes.
Model 2Methane is actively synthesized in the core via hydrothermal reactions and diffuses continuously to the surface.
Model 3Stored methane ice in the crust sublimates steadily as a result of tidal heating from gravitational forces.

Answer

Model 1 matches the hypothesis that methane in crustal clathrates is released during episodic cryovolcanic events. Model 2 matches the hypothesis that methane is synthesized in the core and diffuses continuously. Model 3 matches the hypothesis that stored crustal methane ice sublimates due to tidal heating.

Model 1 is correctly paired with the hypothesis of cryovolcanic bursts because it describes episodic crustal melting driven by rising heat plumes. Model 2 is correctly paired with the synthesis hypothesis because it describes serpentinization (chemical synthesis) in the core and steady diffusion. Model 3 is correctly paired with the tidal sublimation hypothesis because it describes crustal ice sublimating under gravitational tidal flexing.

Step-by-Step Solution

Analyze Model 1's description.

Model 1 describes methane stored in clathrates released in episodic, brief bursts due to mantle heat plumes melting the crust.

This corresponds directly to the statement about episodic cryovolcanic events and crustal clathrate storage.

Analyze Model 2's description.

Model 2 describes chemical synthesis (serpentinization) of methane in the core and steady diffusion through tectonic fractures.

This matches the statement about active synthesis in the core and continuous diffusion.

Analyze Model 3's description.

Model 3 describes tidal heating from gravitational interactions sublimating primordial crustal methane ice steadily.

This matches the statement about sublimation of crustal ice due to gravitational tidal forces.

Key Concept

Identifying Hypotheses and Beliefs

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Topics

More questions from this topic